Bo Qiao
email: bo.qiao@laplace.univ-tlse.fr

; Gilbert

Christian Laurent

Contributing mechanisms to cathodoluminescence and AC electroluminescence spectra in polypropylene and polyethylene thin films

Keywords: MOTS-CLES -Electroluminescence, Cathodoluminescence, Polypropylène, Polyéthylène, Vieillissement électrique, Mécanismes de luminescence Electroluminescence, Cathodoluminescence, Polypropylene, Polyethylene, Electrical ageing, luminescence mechanisms

RESUME

-L'électroluminescence (EL) des isolants polymères est étudiée car elle peut permettre d'approcher les phénomènes de vieillissement électrique en fournissant la signature optique d'espèces excitées sous champ électrique. Dans ce travail, la nature des centres luminescents impliqués dans l'EL de deux types polyoléfines -polypropylène et polyéthylène, est étudiée, en comparant les spectres d'émission résolus en longueurd'onde à ceux obtenus sous excitation par faisceau d'électrons excitation (ou cathodo-luminescence -CL). La similarité des distributions spectrales du polypropylène montre que les mécanismes d'excitation de la luminescence sont les mêmes. Outre les similitudes remarquables entre spectres d'EL et de CL, indiquant une excitation de l'EL par un processus d'électrons chauds, nous montrons que les différents spectres peuvent être décomposés en une série de spectres élémentaires impliquant des groupes insaturés.

Introduction

Insulating polymers are used in a variety of applications in electrical engineering, such as cables, generators, transformers, capacitors, from personal computers to car manufacturing, from living facilities to military installations [START_REF] Teyssedre | Advances in High-Field Insulating Polymeric Materials Over the Past 50 Years[END_REF][START_REF] Reed | Advances in polymer dielectrics over the past 50 years[END_REF]. Electrical ageing and breakdown in insulating polymers is of fundamental interest to the researchers, the design engineers, the manufacturers and the customers. In this respect, Partial Discharge (PD) is a harmful process leading to ageing and failure of insulating polymers. However, with the development of the materials and apparatus, PDs can be weakened or avoided in some situations, e.g. extra high voltage cables, capacitors, etc. Therefore, there is urgent demand for understanding electrical degradation mechanisms under high energy particles or electric field intensity, pushing the limit of electrical properties in insulating polymers.

Electroluminescence (EL) along with other luminescence techniques, like cathodoluminescence (CL) is an exciting field of research for probing insulating polymers, because it gives insight into electrical ageing and breakdown process, since firstly reported in 1967 by Hartman [START_REF] Hartman | Electroluminescence in Organic Polymers[END_REF]. EL is an original technique, contributing to uncover the nature of charge transport mechanisms and electrical ageing. It provides a very interesting information, of photophysical nature, revealing excited states in the polymer, coupled to the electrical behavior of the material, especially with charge carriers in the material that are at the origin of the electroluminescence excitation through the exchange of kinetic or potential energy. However, the essence of EL and the links between EL and electrical ageing or breakdown are still debatable. Insulating polymers, such as polyolefins, have a large band gap (approximately 9 eV), with deep trapping centers mainly due to structural defects, impurities, or additives. EL can originate from hot electron carriers and/or recombination of charge carriers. More evidences and investigations need to be carried out to identify the excitation processes.

Materials and experimental

Materials

Measurements were carried out on different polyolefin materials, being bi-axially oriented polypropylene (BOPP) films of 17.8 μm thickness supplied by KOPAFILM, Germany, cross-linked polyethylene (XLPE) films of 150 μm thickness peeled from high voltage cable, and additive-free low density polyethylene (LDPE) of 120 μm thickness investigated in a previous work [START_REF] Teyssedre | Identification of the components of the electroluminescence spectrum of PE excited in uniform fields[END_REF]. BOPP films are "hazy" films with rough surfaces to promote impregnation of capacitors. These polyolefin materials are widely used in electrical and electronic industry. In an ideal structure, PP and PE should be non-luminescent materials in the visible domain since constituted of only saturated bonds. Luminescence arises because of the presence of in-chain defects such as oxidized groups or double-bonds, of impurities such as traces of catalysts, of additives (e.g. antioxidants) or by-products (as crosslinking by-products in the case of XLPE). By comparing emission from these different polyolefins, it should be possible to unravel the different origins.

Light analysis setups

Both cathodoluminescence (CL, or called electron beam induced luminescence, EBIL) and electroluminescence (EL) analyses were performed at room temperature under high vacuum (about 5x10 -7 mbar) in a specially-designed multipurpose chamber in order to avoid discharges in the ambient atmosphere. Light detection is carried out by a grating monochromator (4.5 nm in resolution) coupled to a liquid nitrogen cooled charge coupled device (CCD) camera for spectral analysis which covers the wavelength range from 300 nm to 850 nm. Both surfaces of samples were metallized with semi-transparent layers of gold as shown is Figure 1 (b) deposited by cold sputtering (thickness: 30 nm, diameter: 50 mm) for EL measurement. Otherwise, these samples don't need any pretreatment for the CL measurement.

Electron beam gun which employ focused electron beams as shown in Figure 1 (a) was used to provide electron beam of energy up to 5 keV for the cathodoluminescence measurement. The filament is at high voltage and the anode at the ground. The distance between the electron gun and the sample on the holder is about 40 mm. The axis of the gun is at 50 o to the normal of the sample plane rendering possible light detection along the normal to the samples. The irradiation area is about 1 mm 2 . The beam current is about 1 µA. Emission spectra were recorded for different electron beam energies from 2 keV to 5 keV and for different radiation time up to 210 seconds with the same beam energy.

The specially-designed electrodesa ring electrode connecting to alternate current (AC) supply and a plane electrode connecting to the ground as shown in Figure 1 (b), provide uniform AC electric field for the electroluminescence measurement. The light emission from the center of the ring electrode through the center hole of the mask can be recorded by the CCD. The internal diameter of the ring electrode is 20 mm, the external diameter of that 30 mm. EL spectra were recorded under AC electric stress at 50 Hz frequency under field up to 250 kV/mm for BOPP and up to 45 kV/mm for LDPE.

Photoluminescence (PL) measurements can be also achieved in the same specially-designed multipurpose chamber at ambient atmosphere, excited with a xenon lamp which covers the wavelength range from 200 nm to 700 nm.

Results and discussions

AC EL spectral analysis

The EL spectra of Au-BOPP-Au samples are shown in Figure 2 (a). The emission spectrum can be analyzed as composed of two contributions with different field dependences: a contribution in the red domain of the spectrum, centered at 750-800 nm, dominating at low field, and another one centered at about 570-580 nm, dominating at relative high field. The red component emission has been attributed to relaxation of surface plasmons or to interface states [START_REF] Qiao | AC electroluminescence spectra of Polyethylene Naphthalate: Impact of the nature of electrodes[END_REF]. It is dependent on the nature of the electrode metal. The bulk emission contains more information on physical and chemical process in the BOPP samples under high field. Figure 2 (b) shows the AC EL spectra of both PP from Figure 2 (a) and PE from previous work [START_REF] Teyssedre | Identification of the components of the electroluminescence spectrum of PE excited in uniform fields[END_REF]. They have the same crest wavelength at about 570-580 nm and the same spectrum shape except the red emission component, implying they derive from the same or similar luminescent mechanisms. It must be stressed that intensity of the red emission component changes somewhat from sample to sample. It is the dominant emission process at low AC field with gold-metalized samples [START_REF] Teyssedre | Identification of the components of the electroluminescence spectrum of PE excited in uniform fields[END_REF].

The formation of excitons and subsequent relaxation through a dissociative pathway is one of the likely mechanisms for EL in PP and PE. Indeed, the fate of excitons formed upon recombination of electron/hole pairs has been investigated in polyethylene materials using density functional calculations and ab-initio molecular dynamics simulations. Two situations were investigated where excitons are self-trapped along a chain [START_REF] Ceresoli | Exciton self-trapping in bulk polyethylene[END_REF][START_REF] Ceresoli | Trapping of excitons at chemical defects in polyethylene[END_REF] or trapped at chemical defects [START_REF] Ceresoli | Trapping of excitons at chemical defects in polyethylene[END_REF]. The relaxation can occur following different pathways depending on the case. When the excitons are trapped on a chemical defect, the relaxation pathway depends of the nature of the chemical defect leading to trapping of the charges, non-radiative recombination or homolitic bond-breaking. This is of course the last process that is relevant for damage. When the excitons are self-trapped along a chain, CH bonds breaking is promoted according to a recent calculation [START_REF] Bealing | An atomistic description of the high-field degradation of dielectric polyethylene[END_REF]. With the opening of a chemical route, by-products could be produced in excited states and be responsible for emission in a wavelength range that is not typical of the initial chemistry of the polymer. The electroluminescence features in PP and PE reveal their excitons transport and relaxation processes under electric field. PE and PP are both polyolefin, with similar CH bonds and by-products, maybe following the similar degradation route.

CL spectral analysis

In order to achieve more evidences of the common features in luminescence of PE and PP, we reproduced CL spectra of PP and PE films in Figure 3 for different e-beam energies. Figure 3 (a) and (b) are the CL spectra of BOPP, while Figure 3 (c) and (d) are the CL spectra of XLPE. They reveal a relatively strong emission (intensity is about x600 that of AC EL spectra) when comparing to AC EL in Figure 2. The CL emission is due to the energetic carriers injected in the samples during the electron beam radiation.

For PP samples, a main peak at about 573 nm and several shoulders at lower wavelength, i.e. 505 nm, 415 nm, and 328 nm are evidenced; for PE samples, the main peak is also at about 573nm but the shoulders components are weaker than in PP. The main peak in CL spectra also has the same wavelength vs. that in EL spectra, which infers that EL also derives mainly or partly from hot electron carriers. Both the BOPP films and XLPE films contain antioxidant and some other additives, but the nature is not the same in the two materials.

CL spectra exhibit high sensitivity to impurities, point defects, structural modifications, etc [START_REF] Zamoryanskaya | Cathodoluminescence of radiative centers in wide-bandgap materials[END_REF]. Exposure of materials to electron beam with such an energy induces a number of processes in the samples, which lead to the formation of secondary and backscattered electrons, and also generate characteristic radiation and bremsstrahlung, plasmons, and Auger electrons, which were studied in detail in [START_REF] Pines | Elementary excitations in solids: lectures on phonons, electrons, and plasmons[END_REF][START_REF] Newbury | Scanning electron microscopy and X-ray microanalysis[END_REF]. The electron beam can excite the deep traps to excited states or create electron-hole pairs at luminescent centers, which could then go back to ground level through transition, simultaneously emitting light. From normalized CL spectra of PP in Figure 3 (b), we can see that the shoulders have a dependence on the electron beam energy. These shoulders will be analyzed and decomposed below. In order to uncover the nature of the CL main peak at 573 nm, we investigated the time-resolved spectral analysis of both BOPP and XLPE. CL spectra were carried out after different irradiation time with electron beam as shown in Figure 4 (a) and (c). The relative intensities of the four peaks or shoulders are not evidently variable as shown in Figure 4 (b) and (d), while CL intensity of both BOPP and XLPE decreases a lot within about 60 seconds and then decrease slowly with the radiation time as shown in Figure 5. The samples emit much less light after about 60 seconds. It can be speculated that at that time the samples have been almost aged. In our experiment, the irradiated area on both PE and PP samples have turned to be light brown from transparent, which directly proves that they have been aged during the electron beam irradiation. Along with the CL intensity decreasing with time, we can infer the CL emission is accompanied by electrical degradation of the insulating polymers. Furthermore, the CL spectrum -especially the main peak at 573 nm may be a signature of electrical degradation in these polymers.

Spectral analysis and reconstruction of elementary components

We have compared the normalized CL spectra of PE and PP in Figure 6 (a). Their spectra both contain the same main peak at 570-580 nm. However these shoulders in PE are weaker than those of PP. In order to investigate the origin of these peaks and shoulders, we have also compared CL and EL spectra of PP to Fluorescence (FL), Chemiluminescence (CHL), due to thermal oxidation [START_REF] Tiemblo | Chemiluminescence spectral evolution along the thermal oxidation of isotactic polypropylene[END_REF], Recombination-induced Luminescence (RL) [START_REF] Teyssedre | Spectral analysis of optical emission due to isothermal charge recombination in polyolefins[END_REF] of PP films as shown in Figure 6 (b). The FL in Figure 6 (b) can account for the component at 328 nm in CL. The photo-induced luminescence derives from a physical process and does not contribute to the electrical ageing. The UV-visible transmission spectrum of BOPP films reveal an absorption maximum at 200 nm, and two absorption shoulders at 230 nm and 280 nm, which are exactly the same two excitation peaks for the Fluorescence. The CHL has been investigated during the thermal oxidation [START_REF] Tiemblo | Chemiluminescence spectral evolution along the thermal oxidation of isotactic polypropylene[END_REF]. It involves formation of carbonyl functions with a typical peak at 415 nm. The RL has been investigated by contacting the samples with a cold plasma powered at a frequency of about 5 kHz [START_REF] Teyssedre | Spectral analysis of optical emission due to isothermal charge recombination in polyolefins[END_REF]. The light emission is due to the recombination of deposited charge carriers. This makes a little contribution to the CL shoulder at 505 nm, inferring that the charge recombination during electron beam irradiation is less. For the peak at about 570 nm, it has not been identified according to previous works. However, it has a direct correlation with electrical degradation according to our experiments forward. The CL and EL both have main peak at about 573 nm, inferring that they may derive from the same luminescence mechanism due to hot carriers effects and physical/chemical processes. However EL contains less components at 328 nm and 415 nm, and more component at 505 nm, implying that recombination processes play a significant role under AC stress. The CHL component in the CL spectrum of PP is relatively strong, pointing to the formation of numerous of carbonyl functions and these chemical transformations make contributions to degradation. These elementary components together reflect electrical degradation in insulating polymers under electric stress.

Conclusion

Electroluminescence (EL) and Cathodoluminescence (CL) of polyethylene and polypropylene have been recorded and compared. We have shown that the CL of PP along with PE involves several bands already identified with other excitation sources and related to carbonyl and unsaturated groups. Emission spectra of PE and PP exhibit the same contributing processes, pointing towards chain defects and degradation products as luminescent species. The common and unique feature of EL and CL spectra is the appearing of a band at about 570 nm, inferring that they may mainly derive from the same luminescence mechanisms and physical/chemical processes. We also show that the spectra especially the band at about 570 nm have a direct correlation with electrical degradation of samples. Identification of these spectral components would be helpful to interpret the nature of light emission from polyolefin and other insulating polymers and to bridge the gap between space charge distribution and electrical ageing or breakdown.

Figure 1 :

 1 Figure 1 : Configuration of light analysis setups: (a) for CL and (b) for EL.

Figure 2 :

 2 Figure 2 : EL spectra under 50 Hz AC stress, (a) Spectra of Gold metalized BOPP film integrated for 300 s at different fields; (b) Comparison of normalized EL spectra of BOPP under 247 kV/mm from Figure 2 (a) and of LDPE under 45 kV/mm from [4].

Figure 3 :

 3 Figure 3 : CL spectra obtained with a CCD integration time of 10 s. (a), (c): Spectra of BOPP and XLPE films respectively, under different electron beam energies, (b), (d): Normalized CL spectra of BOPP film in (a), and of XLPE film in (c), respectively.

Figure 4 :Figure 5 :Figure 6 :

 456 Figure 4 : CL spectra under electron beam energy of 5 keV after different irradiation time, (a) Rough spectra of BOPP film, (b) Normalized spectra of BOPP film from (a), (c) Rough spectra of XLPE film, (d) Normalized spectra of XLPE film from (c). 0 50 100 150 200 0 400 800 1200 1600 2000 Intensity at 573 nm


Prof Yun T Wang

Teng Ben
email: tben@jlu.edu.cn

Shilun Qiu

Valentin Valtchev

Prof. S T Ben

Prof S Qiu

Prof. V V Valtchev

Aligned High Density Semi-Conductive Ultra-Small Single-Walled Carbon Nanotubes

Keywords: aligned SWCNTs, AlPO-5, molecular wire, high density carbon nanotube

Zeolite type material (AlPO-5, AFI-type) with rod-like morphology and mono-dimensional channel system running along the long crystal axis was vertically grown on a stainless-steel plate. The organic template used in the synthesis was carbonized to generate single-walled carbon nanotubes (SWCNTs). Thus, SWCNTs with a diameter of 0.4 nm, perfectly aligned and vertically oriented to the support surface with a density of 2.6 × 10

5 SWCNTs μm 2 , were obtained. The free end of AlPO-5 crystal was chemically etched in order to create contact surface and measure the conductivity of SWCNT@AlPO-5 film which was found to be 4.16 × 10

1 Ω 1 cm 1 . This approach of aligned SWCNTs can be applied to different types of substrates, thus opening the road to practical uses of SWCNTs.

Single-walled carbon nanotubes (SWCNTs) are the most plausible alternative of silicon-based electronic devices due to their exceptional transconductance and current-carrying capacity.

The discovery of multi-walled carbon nanotubes (MWCNTs) by Iijima [3] attracted the interest of different communities and the research in this field constantly grows. [4][START_REF] Tanaka | Carbon Nanotubes and Graphene Edition[END_REF][START_REF] Qin | [END_REF][7][8][9][10][11][START_REF] Andrews | Comprehensive Nano-science and Technology[END_REF][START_REF] Thostenson | [END_REF] The next big step to nano/molecular electronics was the discovery of SWCNTs. [14,15] However, the exceptional potential of SWCNTs can only be explored if they are properly integrated into electronic devices. [16][17][18][19] Arrays of SWCNTs would be ideal for electronic devices if the tubes are aligned and tightly packed. Traditional preparation methods of SWCNTs include arc discharge, [14] laser ablation [20] and chemical vapour deposition (CVD). [21] In the past decade the research efforts were dedicated to the preparation of arrays of densely packed SWCNTs in order to improve the current drive capability, transconductance and cut-off frequency in applied devises prototypes as electrochemical capacitors, [22] and integrated circuits in digital and radio frequency electronics. [23] Researchers from IBM pointed out that a density of 125 SWCNTs μm 1 will have to be achieved in order for carbon nanotubes to be included in integrated circuits (IC). [24] At present, the preparation of large-area high-density nanotube arrays is still a challenge, although various physical and chemical approaches have been employed. [25][26][27][28][29][30][31][32][33][34][35][36] Misalignement and non-uniformity of carbon nanotube arrays are the major roadblocks to the practical uses. An alternative approach that could circumvent these difficulties is the use of a porous scaffold that controls the alignment and density of SWCNTs. [37][38][39] Microporous zeolite type crystals with Angstrom size well define pore system present a perfect scaffold for such preparation. [40] The stratege of this work was to select porous materials with ideal straight channels as templates, and AlPO 4 -n family molecular sieves were preferred. As a one-dimensional quantum wires, carbon nanotubes have different conductivity due to their different sizes, the thinner in diameter and smaller the spacing between the tubes, the higher density arrangement of the same area would be. Moreover Tang et al. have already demonstrated the possibility to grow 0.4 nm SWCNTs in AlPO-5 (AFI-type) crystals. [41] Here we report a method that allows fabricating ultra-high densely packed and aligned SWCNTs. Film of densely packed AlPO-5 crystals was grown on a stainless-steel substrate with size 4 x 4 cm (Figure 1A,B). The crystals building the film are 5 x 100 μm in size, exhibiting the typical of AlPO-5 hexagonal prism morphology. The long c-axis, along which is running the twelve-membered ring channel, is vertically oriented to the substrate surface. The vertical orientation of the crystals is confirmed by the XRD pattern of the film where the (002) peak is very intense. The height of (102) peak is reduced substantially (Figure 1C) and the intense peaks with (h00) or (hk0) indices are not visible (Figure 1D). The carbon nanotubes were formed by pyrolysis between 450 °C and 800 °C of the organic template used in the synthesis of AlPO-5.

The process was optimized by using different organic templates and pyrolysis conditions. [42,43] The sample obtained at 800 °C showed the best performance and was selected for more detailed analysis. Being pyrolyzed in vacuum at 800 °C the film remains intact as confirmed by the SEM analysis (Figure S2). The 0.4 nm SWCNTs prepared are aligned and stable when confined in the AFI framework. However, after extraction from the AFI channel system the self-standing nanotubes is difficult to be employed for practical uses due to the strong curvature effect.

No N H band (3174-3241 cm 1

) was observed in the IR spectrum of pyrolyzed sample revealing the full conversion of TrPA (tripropylamine) template (Figure S1). The impact of the temperature of pyrolysis on the formation of SWCNTs was studied by Raman spectroscopy (Figure 2, Table 1). The Raman spectrum of SWCNTs comprises three main segments. [START_REF] Reich | Carbon nanotubes: basic concepts and physical properties[END_REF] The high-frequency region 1500-1620 cm 1 with the G bands near 1600 cm 1 corresponds to the tangential band stretching vibrations. The G band further split into two parts, G + (1615 cm 1 ) and G (1599 cm 1 ), due to the curvature effect. The intermediate-frequency region (1200-1500 cm 1 ), with D band near 1350 cm 1 , corresponds to the carbons with some defects, as the most common case is atomic vacancy defect. The lowfrequency region (200-800 cm 1 ) with a peak centered near 530 cm 1 is attributed to tubular vibrations along the radial direction, which is specific of SWCNTs bearing tubular structures.

[39, 45-47] Figure 2A represents the Raman spectrum of SWCNTs@AlPO-5 film prior to etching, where the radial breath-ing mode (RBM) of SWCNTs@AlPO-5 at 508 and 550 cm 1 is assigned to the semiconducting (4, 2) and (5, 0) SWCNTs. [48] The relative ratio of the RBM to G-band, namely I RBM /I G values range between 0.1 and 4 for different carbon nanotube. [49,50] In this work, the intensity of RBM bands at 534 cm 1 and the line width of the Gband in 1599 cm 1 was 0.19, indicating TrPA was well carbonized into SWCNT inside the AIPO-5 channel. After etching, the RBM bands shifted to lower frequency due to the weakened interaction between the AlPO-5 framework and SWCNTs wall (Figure 2B). The diameter of the SWCNTs (d t ) was estimated to be 0.42 � 0.02 nm by empirical formulas ω RBM = A/ d t (ω RBM is the RBM peak frequeney, A = 223.75 cm 1 nm [51] ), which matches with the TEM observation. The connection of ultra small carbon nanotubes formed in the zeolite channel to the measuring device is probably the most challenging part of this study. We achieved this by controlled etching of the AlPO-5 crystal in 0.15 M KOH ethanol solution. The treatment was performed at room temperature in order to slow down the etching kinetics. The best result was obtained after 25 days of etching. Figure 3A represents the typical hexagonal prisms of AlPO-5 with straight and sharp edges on the pinacoidal face. After etching, the straight edges of AlPO-5 crystal (Figure 3A) became rounded and step of dissolution can be observed on the prismatic face (Figure 3B). Figure 3C shows the [020] and [120] crystal plane of AlPO-5 crystal with interplanar space of 5.90 Å and 4.55 Å, respectively. Partly unmolded carbon nanotubes emerging from zeolite channels can be seen in Figure 3D. As revealed by the TEM study, the diameter of the SWCNTs obtained in the channels of AlPO-5 is 0.42 nm. It should be noted that SWCNT is unstable when all the AIPO-5 was removed by etching. [37,52-54] Thermogravimetric analysis (TGA) was used to estimate the SWCNTs content inside the AlPO-5 (Figure S3). Upon being heated to 600 °C in dry air, the SWCNTs@AlPO-5 film together with the substrate exhibits a weight loss of 0.8 wt.%. Thus, the formation yield of SWCNTs was evaluated to be 12.8%. Considered the size of the AIPO-5 crystals, the density of SWCNTs was estimated to be 2.6 × 10 ). To our best knowledge, this value is among the highest density of SWCNTs to date and surpasses the target (125 CNTs μm 1 ) of IC. [24] The electric transport properties of SWCNTs-containing film were studied after pasting double-sided carbon conductive tape, as shown in Figure 4A.

Current-voltage (I V) properties are measured in the temperature of 27 °C (Figure 4B). The conductivity of the SWCNTs@AlPO-5 film is1.31 × 10

6 Ω 1 cm 1 . Given that each SWCNT in the film is connected in parallel, the conductivity of the single SWCNT inside the AlPO-5 channel is calculated to be 4.16 × 10

1 Ω 1 cm 1 , which is comparable to the previous literature data. [37] The density of carbon nanotube reported previously is summarized in Figure 4C. [55][START_REF] Choi | Sixth IEEE Conference on Nanotechnology[END_REF][START_REF] Franklin | [END_REF][58][59][60][61][62] As can be seen, our strategy provides SWCNTs with a higher density than previously reported methods with the exception of the horizontally oriented CNTs prepared by Cao et al. using the Langmuir-Blodgett method. 63 However, the vertically aligned arrays show higher thermal conductivity and offer advantages for practical applications. [64][65][66][67] Thus the present study represents a big step ahead not only the preparation of aligned densely packed SWCNTs, but also in their production in a form appropriate for practically uses. This work represents a robust method to achieve ultrahigh density vertically aligned SWCNTs arrays.

Owing to the ultra-small diameter of the SWCNTs, which is much smaller than that of the silicon transistors (90 nm) currently used, the future integration density could be improved substantially. Consequently, the resistance loss of the wire and the capacitance between the wires will be reduced, accompanied by the increasing operating frequency and decreasing the energy consumption. [59,68] This may well solve the signal delay problem in the application of logic circuits.

To summarize, AlPO-5 film-derived ultra-small verticallyoriented SWCNTs with diameter 0.4 nm were synthesized by pyrolysis of the organic (TrPA) template. The free-standing end of AlPO-5 crystals was etched in order to connect the ultra-small nano-tubes to a circuit. The conductivity of the SWCNTs@AlPO- ) surpassing the target of 125 SWCNTs μm 1 postulated by Franklin. [24] Each SWCNT in the film is connected in parallel. According to this fact, the conductivity of the single SWCNT@AlPO-5 was estimated to be 4.16 × 10 1 Ω 1 cm 1 . The SWCNTs array is semiconductor type, and its size is far smaller than the dimensions of semiconductor materials currently used in computing and data storage. This material is expected to overcome the size limitation of silicon-based materials and have the potential to be used in electronic devices, significantly increasing computing speed and storage capacity.

Figure 2 .

 2 Figure 2. Raman spectra of SWCNTs@AlPO-5 film subjected to pyrolysis at 800 °C: (A) before and (B) after etching.

Figure 3 .

 3 SEM images of AlPO-5 crystal prior to (A) and after etching (B) with 1453,1473 0.15 M KOH ethanol solution. High resolution TEM image of AlPO-5 crystal 800 534 1233,1291,1387, 1599,1615 (C) and the free extremity of the carbon nanotubes after the crystal etching 1424,1453,1473 (D).

Figure 4 .

 4 Figure 4. Schematic presentation of the experimental setup (A); I V curve of SWCNTs@AlPO-5 film (B); and density of CNTs reported in the previous publications (C).

Table 1 .

 1 Raman bands of the SWCNTs@AlPO-5 thin films obtain after carbonization at different temperatures

	Carbonization RBM temperature frequencies	D band frequencies G band (1200-1500 cm 1 ) frequencies
	(°C)	(400-600 cm	1 )	(1500-1620 cm	1 )
	450	533	1237,1337,1441	1580
	500	537	1224,1335,1452	1588
	550	529	1219,1338,1441	1572
	600	533	1241,1343,1451	1580
	650	536	1249,1335,1452	1588
	700	532	1229,1337,1462	1600
	750	533	1229,1288,1304,	1595,1614
			1344,1394,1430,

Supporting Information Summary

The supporting information contains experimental procedures (Part 1), characterization and calculation process of materials (Part 2). References related to experimental section were show in Part 3 of supporting information. S1-S3 display the IR, XRD and TGA, the corresponding group attribution are also given.


Mariame Akouche

Jean-Pierre Gilson

Nikolai Nesterenko

Simona Moldovan

ד Daniel Chateigner

Hussein El Siblani

Delphine Minoux

Jean-Pierre Dath

Valentin Valtchev

Synthesis of Embryonic Zeolites with Controlled Physicochemical Properties

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

Molecular sieve zeolites are widely used as heterogenous catalysts in a variety of industrial (oil refining, petro-and fine chemicals production..) and environmental (exhaust gas treatment, heavy and radioactive ion sequestration, …) applications. [START_REF] Flanigen | Zeolites in Industrial Separation and Catalysis[END_REF][START_REF] Bellussi | Zeolites and Catalysis:Synthesis, Reactions and Applications[END_REF] They typically offer high surface area, uniform micropores with well-defined topology, strong acid sites, and high thermal and chemical stability. [START_REF] Marcilly | Where and how shape selectivity of molecular sieves operates in refining and petrochemistry catalytic processes[END_REF][START_REF] Vermeiren | Impact of zeolites on the petroleum and petrochemical industry[END_REF][START_REF] Martínez | Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes[END_REF] A unique property of zeolite materials is their shape selectivity, [START_REF] Marcilly | Where and how shape selectivity of molecular sieves operates in refining and petrochemistry catalytic processes[END_REF] a consequence of their active sites being confined in well-defined micropore spaces. However, the presence of such micropores often imposes transport limitations on reactants and products, in particular, those with a size close to or larger than the pore diameter. [START_REF] Martínez | Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes[END_REF] These steps become rate determining in the catalytic activity and the full potential of theses catalysts is not reached. In the case of bulky molecules, larger than zeolite pores, the only accessible and active sites are those located on the outer surface of the crystals and their pore openings. In summary, the problems of diffusion and related low accessibility to the active sites represent a major roadblock in a number of industrial reactions catalyzed by zeolites (cracking, oxidation, esterification, ...). To meet exacting industrial requirements, [START_REF] Landau | Hydrocracking of heavy vacuum gas oil with a Pt/H-beta-Al2O3 catalyst: effect of zeolite crystal size in the nanoscale range[END_REF] much efforts are devoted to preparing zeolite materials with better accessibility and improved transport properties. The most explored avenues to improve catalytic performances were focused on decreasing zeolite crystal size [START_REF] Corma | Delaminated zeolite precursors as selective acidic catalysts[END_REF][START_REF] Vuong | A new route for the synthesis of uniform nanozeolites with hydrophobic external surface in organic solvent medium[END_REF][START_REF] Choi | Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts[END_REF][START_REF] Tsapatsis | A New, Yet Familiar, Lamellar Zeolite[END_REF][START_REF] Smaïhi | Colloidal functionalized calcined zeolite nanocrystals[END_REF] and preparing zeolites containing a system of larger (meso-)pores. [START_REF] Xu | A quantitative study of the structure-activity relationship in hierarchical zeolites using liquid-phase reactions[END_REF][START_REF] Chal | Overview and industrial assessment of synthesis strategies towards zeolites with mesopores[END_REF][START_REF] Perez-Ramirez | Hierarchical zeolites: enhanced utilisation of microporous crystals in catalysis by advances in materials design[END_REF][START_REF] Valtchev | Tailored crystalline microporous materials by post-synthesis modification[END_REF][START_REF] Wei | Tailoring and visualizing the pore architecture of hierarchical zeolites[END_REF][START_REF] Valtchev | High energy ion irradiation-induced ordered macropores in zeolite crystals[END_REF] A mesoporous network connected to the native micropores in zeolite crystals decreases mass transport limitations, but it does not affect the limited intrinsic ability of zeolites to process bulky molecules. Both solutions, nano-zeolites and mesopore-containing zeolites, bear some limitations, in particular the active sites in the zeolite channels remain inaccessible for bulky molecules, and therefore alternative solutions are required. Recently, we addressed this issue by the preparation of zeolites units with sizes of few nanometers. [START_REF] Haw | Supported Embryonic Zeolites and their Use to Process Bulky Molecules[END_REF] These units denoted "embryonic zeolites" exhibit only short-range order and comprise elements of zeolite structure. Their semi-formed unit cells offer easier access of much bulkier molecules to the active sites than their fully crystalline counterpart, which exhibits long range order. The embryonic zeolites were prepared as mono disperse suspension containing nano particles that are uniform in size and composition. [START_REF] Haw | Supported Embryonic Zeolites and their Use to Process Bulky Molecules[END_REF] They exhibit superior catalytic activity, with respect to the fully crystalline material (zeolite) synthesized from the same initial system. For instance, embryonic zeolites synthesized with tetrapropylammonium as structure directing agent exhibit pores in the range 1-2 nm. The extension of zeolite pore size to 1-2 nm would allow to process much bulkier molecules than the "current" available zeolites can process. At present, only Gesilicate zeolites exhibit pores larger than 1 nm, [START_REF] Jiang | Extra-large-pore zeolites: bridging the gap between micro and mesoporous structures[END_REF] while the conventional alumino-silicate zeolites are limited to 1 nm in pore size. Unfortunately, the limited (hydro)thermal stability of Ge-silicate zeolites so far precluded their commercial used. Thus, the quest for extra-large pore zeolitic materials continues to be a topic of high priority. Here, we address this issue by the preparation of a few nanometer large zeolitic nano units which offer full accessibility to their active sites by relaxing diffusion limitations. Sacrificial organic templates are commonly used in the synthesis of nanoporous materials. [START_REF] Manton | Controlled pore sizes and active site spacings determining selectivity in amorphous silica-alumina catalysts[END_REF][START_REF] Corma | Synthesis and characterization of silica-alumina prepared from tetraalkylammonium hydroxides[END_REF] In the synthesis of zeolitic materials the organic template, often called organic structure directing agent (OSDA) plays a key role in the formation of zeolite structure and charge distribution in the framework. [START_REF] Jiang | Extra-large-pore zeolites: bridging the gap between micro and mesoporous structures[END_REF] In general, these are positively charged molecules that balance the negative charge introduced by Al cations in the zeolite framework. Each OSDA has a fixed size/charge ratio; therefore, the total guest volume is determined by the number of guest molecules that will correspond to the framework charge density. [START_REF] Camblor | A new microporous polymorph of silica isomorphous to zeolite MCM-22[END_REF][START_REF] Cantín | Rational design and HT techniques allow the synthesis of new IWR zeolite polymorphs[END_REF][START_REF] Liu | The first zeolite with threedimensional intersecting straight-channel system of 12membered rings[END_REF] The objective of this study is the preparation of embryonic zeolites with pores exceeding 1 nm with a few nanometer particle size and controlled pore size and pore volume. A series of tetraalkylammonium (TAA) cations with size ranging between 6 and 12 Å was employed. The series includes: tetramethylammonium (TMA + ), tetrapropylammonium (TPA + ), trimethyladamantylammonium (TMAd + ), tetrabutylammonium (TBA + ) and tetrahexylammonium (THA + ). With the exception of THA + , which is too big to yield a zeolite-type microporous material, all other OSDA generate zeolite structures. [START_REF] Szostak | In Handbook of molecular sieves: structures[END_REF] Embryonic zeolites with different micropore volumes and specific surrface areas are obtained. Their catalytic activities are evaluated in the dealkylation of a model molecule, 1,3,5-triisopropylbenzene (1,3,5-TiPBz) hardly penetrating the micropores of any industrially relevant zeolite. It is, therefore, commonly used to study the external surface properties of zeolites, including those with the large pores. [START_REF] Peng | Testing the limits of zeolite structural flexibility: ultrafast introduction of mesoporosity in zeolites[END_REF][START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] EXPERIMENTAL SECTION Preparation of embryonic precursors All syntheses started from clear homogenous sols with molar composition 9OSDA : 0.25Al2O3 : 25SiO2 : 430H2O : 100EtOH, where OSDA: Tetramethylammonium hydroxide (TMA.OH 25% in water, Alfa Aesar), Tetrapropylammonium hydroxide (TPA•OH 20% in water, Alfa Aesar) Trimethyladamantylammonium hydroxide (TMAd.OH 25% in water, Sachem), Tetrabutylammonium hydroxide (TBA.OH 40% in water, Alfa Aesar) and Tetrahexylammonium hydroxide (THA.OH 20% in water, Sigma Aldrich). After mixing the OSDA with distilled water, aluminum sulfate (98%) and tetraethylorthosilicate (TEOS 98%), the solution was hydrolyzed at room temperature for 6 h in a closed polypropylene bottle. The complete hydrolysis was confirmed by the appearance of a clear monophasic solution. Then, this solution was either dried by freeze drying at -94°C under vacuum (to avoid any further crystallization) or hydrothermally treated at 90°C for 12, 15, 18, 144 and 216 h as the kinetics of the synthesis depends on the nature of the OSDA. After the synthesis, the solid was recovered by freeze drying and further calcined at 550°C for 5h in a static oven under air.

The following series of zeolite precursor (P) samples were prepared by: -Room temperature synthesis (PRT): PRT-TMA, PRT-TPA, PRT-TBA, PRT-TMAd, and PRT-THA.

-Hydrothermal synthesis: Px-y-SDA, where x is the temperature in °C; and y the crystallization time in h; ex: P90-15-TMA, P90-216-TMAd, … A highly crystalline nano-sized ZSM-5 prepared from the same initial suspension at 100 °C for 48 h was used as a reference sample. Characterization All materials were characterized by powder X-ray diffraction (PXRD) using a PANalytical X'Pert Pro diffractometer with average Cu Kα radiation (λ = 1.5418 Å). We used a -2 scan in the 3-50° 2θ-range and a 0.02° step. The whole pattern was fitted using the combined analysis formalism [START_REF] Chateigner | In Combined Analysis: Structuretexture-microstructure-phase-stresses-reflectivity analysis by X-ray and neutron scattering[END_REF] implemented in the MAUD program [START_REF] Lutterotti | Total pattern fitting for the combined sizestrain-stress-texture determination in thin film diffraction[END_REF] a software using an extended Rietveld [START_REF] Rietveld | A profile refinement method for nuclear and magnetic structures[END_REF] analysis approach. Since severe line broadening was observed in the diffraction diagrams, we analyzed those within the Combined Analysis approach. The instrumental contribution to the line broadening was calibrated on the LaB6 srm660b standard powder from the National Institute of Standards and Technology. The Popa [START_REF] Popa | The (hkl) dependence of diffraction-line broadening caused by strain and size for all Laue groups in Rietveld refinement[END_REF] formalism was then used to describe anisotropic crystallite sizes and shapes. No preferred orientation was detected during the fit. The ZSM5 structural model n°1505105 from the Crystallography Open Database [START_REF] Gražulis | Crystallography Open Database-an openaccess collection of crystal structures[END_REF] was used as a starting model in the refinement. Nitrogen adsorption measurements were carried out on a Micromeritics ASAP 2020 surface area analyzer. The calcined samples were analyzed after degassing at 300 °C. The isotherms were recorded using the ASAP 2020 analysis program. The microporous volume (Vmic / cm 3 .g -1 ) and the external surface area (Sext / m 2 .g -1 ) were obtained from the t-plot method based on the Harkins-Jura equation. The macro-and mesopores size distribution was obtained from the desorption branch using the Barrett Joyner Halenda algorithm assuming cylindrical pores. For refined analysis, micro-mesopores size distribution was extracted from Density Functional Theory modelling of the adsorption branch. TG-DSC measurements of different samples were carried out on a SETSYS evolution instrument (SETARAM). About 10 mg of each sample was introduced in an alumina crucible that is loaded in the analyzer chamber. The sample was heated from 30 °C to 800 °C with a heating ramp of 5 °C•min -1 under air (flow rate: 40 mL•min -1 ). All NMR measurements were done with 4-OD mm zirconia rotors and with a spinning speed of 12 kHz. The solid state 2 -13 C CP-MAS NMR spectra were recorded on a Bruker Avance 400 spectrometer operating at 100.6 MHz. During the pulse program, a π/2 pulse of 3.7 μs on 1 H, a contact time of 2 ms and a recycle delay of 2 s were used. [START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] Al MAS NMR was recorded on a Bruker Avance 500 spectrometer operating at 130.3 MHz. [START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] Al MAS NMR was obtained with a π/12 pulse and a recycle delay of 1 s. The amount of nontetrahedral Al was estimated by the integration of peak area using Dm-fit program. The results were verified by the Top Spin program. The solid state [START_REF] Lutterotti | Total pattern fitting for the combined sizestrain-stress-texture determination in thin film diffraction[END_REF] Si NMR (1pulse) was also recorded on Brucker Avance III-HD 500 spectrometer (11.7 T) operating at 99.3 MHZ, using zirconia rotors of 4 mm outer diameter spun at 12 KHZ. A single pulse excitation (30° flip angle) is used with a recycle delay of 30s. TMS was the reference for [START_REF] Lutterotti | Total pattern fitting for the combined sizestrain-stress-texture determination in thin film diffraction[END_REF] Si and [START_REF] Chal | Overview and industrial assessment of synthesis strategies towards zeolites with mesopores[END_REF] C while a 1M Al (NO3)3 solution was used for [START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] Al. 129 Xe NMR experiments were performed on a Bruker AV III 400 wide-bore spectrometer equipped with a 10 mm BBO probe, operating at a frequency of 110.64 MHz for 129 Xe. Prior to each experiment, the sample was introduced into a home designed (10 mm O.D.) NMR tube and dehydrated under high vacuum overnight at 413 K. The hyperpolarized (HP) 129 Xe gas was obtained using a home-built xenon polarizer based on the spin-exchange optical pumping (SEOP) technique. [START_REF] Happer | Optical pumping[END_REF][START_REF] Happer | Polarization of the nuclear spins of noble-gas atoms by spin exchange with optically pumped alkali-metal atoms[END_REF] Xe NMR spectra were acquired under a continuous recirculating flow of 50 mL•min-1 of a gas mixture containing 4%Xe, 6%N2 and 90%He at a total absolute pressure of 1.5 bar. For all variable-temperature (VT) measurements and after each temperature change performed at a speed of 5 K•min -1 , a delay of ∼20 min was generally necessary to ensure a homogeneous temperature all over the sample, and this stability was checked by directly monitoring the xenon chemical shifts. All spectra were referenced to free xenon gas at 0 ppm. The IR spectra were recorded on a SHIMADZU IR Affinity-1 Fourier Transform Infrared Spectrophotometer using the KBr pellet technique. Pyridine and collidine adsorption were used to evaluate the acidity and accessibility of the samples. The study was performed using a standard in-situ FTIR set-up. Infrared spectra were recorded on a Nicolet Magna 550 FTIR spectrometer equipped with a DTGS detector at 4 cm -1 optical resolution, with one level of zero-filling for the Fourier transform. Prior to the measurement, the sample was grinded and pressed into a self-supporting disc (diameter: 2 cm, approx. 5 mg cm -2 ) and activated in vacuum (ca. 10 -6 hPa) at 460 °C for 2 h at 2 °C•min -1 . After cooling to room temperature, the spectrum of the sample was recorded for further use as a reference. Then, a pressure of 1.33 hPa of probe molecule (P.M.) was established in the cell at ambient temperature to reach saturation. The wafer was heated at 100 °C for 15 min to facilitate diffusion of P.M. into the sample. Successive evacuations were performed at 25 °C, 50 °C, 100 °C, 150 °C, 200 °C, 250 °C, 300 °C, and 350 °C at 15 min intervals. All spectra were normalized to 2.5 mg cm -2 wafer. The amounts of acidic sites were determined using the areas of the bands at 1450 cm -1 (Lewis) and 1545 cm -1 (Brønsted) in case of pyridine adsorption and at 1644 cm -1 (Brønsted) in case of collidineadsorption. The molar extinction coefficients (Ɛ) used for quantification were Ɛ1545 (B-pyridine) = 1.8 cm µmol -1 , Ɛ1455 (L-pyridine) = 1.5 cm µmol -1 and Ɛ1644 (B-collidine) = 10.1 cm µmol -1 . [START_REF] Nesterenko | The use of the consecutive adsorption of pyridine bases and carbon monoxide in the IR spectroscopic study of the accessibility of acid sites in microporous/mesoporous materials[END_REF] The OMNIC version 7.3 SP1 program was used for data processing. The Transmission Electron Microcopy (TEM) investigations were carried out on a double corrected Cold FEG Jeol ARM Analytical TEM. Due to the materials high sensitivity to electron beam irradiation, an accelerated voltage of at 80kV was employed and the micrographs were acquired under Scanning TEM (STEM) mode using the High Angular Annular Dark Field (HAADF) detection methodology. In this approach, a 0.1 nm diameter beam scanned the region of interest and the image was recorded at a camera length of 8 cm and in the semi angular range 70 -280 mrad. Size calibrated Au NP were employed for the STEM fine alignments. The images were acquired at a speed of 12 µs/px for image sizes of 1024x1024 px using the Digiscan Plugin implemented in the Digital Micrograph software. Few drops of an ethanol-based solution containing the specimens dispersed in ethanol and using ultrasounds were deposited on a holey-carbon membrane disposed on 300 mesh Cu-grids.

Catalytic testing

The catalytic performances were evaluated in the dealkylation of 1,3,5-triisopropylbenzene (TiPBz) in a down flow atmospheric reactor. In a typical catalytic test, 20 mg of catalyst (dry mass) was loaded at the center of a stainless-steel tubular reactor (internal diameter of 1/2'') and activated in-situ at 460 °C (ramping from room temperature at 5 °C•min -1 ) under a dry air flow (50 ml•min -1 ) for 1 h. The temperature was subsequently lowered to 300 °C under nitrogen flow (50 ml•min -1 ). The nitrogen flow was then diverted to a saturator (operated at 70 °C) filled with TiPBz (Alfa Aesar, 97%), generating a TiPBz partial pressure of 170 Pa feeding the reactor. The WHSV (Weight Hourly Space Velocity) was held constant at 8 h -1 for all tests. The conversions were measured at 300°C over 100 min. The online analysis of the products and unconverted reactant, transferred via a line heated at 150 °C to a gas sampling valve, were monitored by a Varian CP-3800 Gas Chromatograph equipped with a flame ionization detector (FID) detector and a HP-PONA cross-linked methyl siloxane column, 50 m (L) x 0.2 mm (ID) x 0.5 µm (film thickness).

The temperature of the column was kept at 160 °C throughout the measurement. The injection temperature was maintained at 200 °C while the detection temperature was maintained at 250 °C.

RESULTS AND DISCUSSION

Discrete nanometer sized embryonic zeolites can only be obtained if the polymerization between silica and alumina precursor species and the OSDA is closely controlled, to avoid the formation of large and dense gel particles with various sizes and compositions. This is also a necessary condition to assess their physicochemical properties. Such a general rule is particularly important with amorphous material lacking long range structural order. Optically clear sols containing only discrete gel particles are therefore used in all our syntheses to harvest solids with similar size, composition, and porosity. Impact of OSDA on the physicochemical properties of embryonic zeolites. Alkylammonium cations of varying sizes acting as organic structure directing agents (OSDAs) allow studying the properties of the porous solids harvested from syntheses performed at room temperature (RT). After complete hydrolysis of the silica source (TEOS), the resulting samples are freeze dried and characterized. According to DLS, all precursor sols present a monomodal particular size distribution with a size between 1 and 10 nm, Such fitted parameters are only helping the fit, but could not represent the first significant contribution appearing below 2 = 10°. This latter contribution is associated with the periodical arrangement of the embryos depicted by the electron density contrasts observed in TEM images (see Figure 2C) and cannot be modeled in the XRD diagrams using the MFI-type structure. We instead used a simple Gaussian background contribution to account for it in the Rietveld fits. As a result (see Figure 3B insert), the first and second scattering contributions are located around 3.68 and 7.1 Angstroms, respectively. In MFI-type structure, such contributions characterize the mean distances between closest Si-O polyhedra, with corresponding first and second scattering orders. The first distance at 3.68 Angstroms is also close to the one observed in fumed silica of around 3.9 Å (see Figure S3A) while no periodicity is observed (see Figure S3B). As X-ray diffraction is not the best technique to probe shortrange orders, on such embryonic zeolites we resorted to infrared spectroscopy (IR) to characterize the structure of ultrasmall zeolite embryos. The IR spectra display three main absorption bands around 1080 (with a shoulder at 1200 cm -1 ), 800 and 460 cm -1 , Figure S4. The first two correspond to asymmetric and symmetric Si-O stretching motions and the last one to a bending Si-O-Si mode. A shoulder at 560 cm -1 is also observed and assigned to the bending vibrations of external Si-O. [START_REF] Pichat | Infra-red structural study of various type L zeolites[END_REF] The bands around 560 and 1200 cm -1 are generally attributed to the double-membered ring and external asymmetric stretching in the MFI structure, respectively [START_REF] Jansen | Identification of ZSM-type and other 5-ring containing zeolites by ir spectroscopy[END_REF] while, the optical density ratio of 560 and 460 cm -1 bands is commonly used to determine the zeolite crystallinity. [START_REF] Jansen | Identification of ZSM-type and other 5-ring containing zeolites by ir spectroscopy[END_REF] The crystallinities of the PRT-TMA, PRT-TPA, and PRT-THA samples are similar according to such an IR study. The synthesized materials exhibit a type I isotherm with a significant uptake at low relative pressure followed by horizontal adsorption-desorption branches. A closer look at the isotherms reveals small differences between the material synthesized with TMA (PRT-TMA) and larger templates. The isotherm of PRT-TMA is type Ia characteristic of ultra-micropores (< 0.7 nm), whereas the others (TPA, TBA, TMAd, THA) are of type Ib, characteristic of super-micropores (1-2.5 nm) according to the classification of IUPAC. [START_REF] Thommes | Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report)[END_REF] The latter isotherms show much higher uptake indicative of larger micropore volumes. The isotherm of nanosized ZSM-5 is included in Figure 4 and the data derived from the isotherm summarized in Table S1. The micropore volume of the MFI type material is similar to PRT-TMA and much lower than that of the embryos synthesized with larger templates. However, the total pore volume of the crystalline material is higher due to textural meso-porosity, revealed by the slope of the isotherm in the 0.2 -0.8 pressure range and the second uptake in the 0.9-1.0 range, between nanosized zeolite particles. Such a textural porosity is not present in the embryonic zeolite. If some textural pores exist, i.e. pores between ultra-small nano particles (3-4 nm) formed around the template, these pores remain in the microporous range.

The data summarized in Table S1 show that the microporous volume and specific surface area increase with the size of the SDA used. More precisely, Vmicro and SBET increase from 0.17 to 0.47 cm 3 .g -1 and from 418 to 1095 m 2 .g -1 for TMA and THA, respectively. A small increase in micropore volume (TBA>TMAd>TPA) is noticeable.

In general, templates with approximately similar sizes yield materials with very close specific surface area and micropore volume; a close positive correlation between the size of the OSDA and the Vmicro and SBET is indeed observed on theses samples. It is well known that tetraalkylammonium cations play a key role in zeolite synthesis by ordering around them aluminosilicate species, akin to water clathrates, by progressive displacement of hydrogen bound water molecules. [START_REF] Derouane | Synthesis and characterization of ZSM-5 type zeolites I. physico-chemical properties of and intermediates[END_REF][START_REF] Gittleman | Role of tetrapropylammonium cations in gel-phase silicalite synthesis[END_REF][START_REF] Corma | A large-cavity zeolite with wide pore windows and potential as an oil refining catalyst[END_REF][START_REF] Corma | ITQ-15: The first ultralarge pore zeolite with a bi-directional pore system formed by intersecting 14-and 12ring channels, and its catalytic implications[END_REF] As long as synthesis is stopped before crystallization, the harvested materials are silica-alumina matrices organized around these OSDAs and form cages of different volumes depending on the size of SDA used. The pore size distributions and the cumulative pore volumes of PRT-TPA and PRT-THA, extracted by DFT using a cylindrical geometry (model "N2-cylindrical pores-oxide surface") are displayed in Figure S5. The EZ prepared with TPA has a wide distribution of pore widths ranging between 8 and 20 Å with the highest population of pores smaller than 14 Å; they correspond to a cumulative pore volume of 0.15 cm 3 .g -1 . Moreover, the EZ prepared in the presence of THA does not contain pores with size below 1 nm. The population of large pores (> 14 Å) is the most largely presented in this sample. Despite their higher Vmicro and SBET, no additional larger pores are observed, so pores larger than 14 Å dominate in this material. This is clear from the increase of their incremental volume and the decrease of the cumulative pore volume of pores smaller than 14 Å from 0.15 to 0.09 cm 3 .g -1 . Some textural pores represented by a large peak centered at about 27 Å, present in PRT-TPA. These data unambiguously imply that the size of the OSDA determines the pore size of the embryonic zeolites; a smaller OSDA yields pores of smaller width while larger OSDA leads to larger pores. The pore structure of EZ can be studied by relating the confinement of Xe molecule to their chemical shift. [START_REF] Chen | A new approach to determination of micropore size by 129Xe NMR spectroscopy[END_REF] In order to gain more insight into the structure and properties of the embryonic zeolites, the samples are further characterized by thermal analysis (TG/DSC, Figure S6) and [START_REF] Chal | Overview and industrial assessment of synthesis strategies towards zeolites with mesopores[END_REF] C CP MAS NMR spectroscopy, Figure S7. [START_REF] Gabelica | The use of combined thermal analysis to study crystallization, pore structure, catalytic activity and deactivation of synthetic zeolites[END_REF] Prior to TG-analyses, the samples are equilibrated overnight under a 79 % relative humidity at room temperature. The thermograms of different samples are fairly similar to two well established regions, a first, between room temperature and 200-250°C and a second between 250 and 500°C. The weight loss below 200°C is associated with an endothermic peak and attributed to water release. The weight loss at higher temperature (250-500°C) is associated with an exotherm (DSC) and corresponds to the OSDA oxidation. Compared to a crystalline zeolitic material, the embryonic zeolites are much more hydrophilic. For instance, the water content of ZSM-5 is about 5%, while its amorphous counterpart synthesized with TPA contains about 35 wt% water. It is of note that water content increases with the increasing size of the OSDA used, from 38 to 48 and 52% with TMA, TPA, and THA, respectively. Most of the water is released at about 60°C on PRT-THA and at higher temperatures on samples containing smaller structure directing agents (PRT-TPA and PRT-TMA); this further implies that larger (hydrated) OSDAs lead to embryos with more open structures. The OSDA oxidation includes several steps; one common around 280-300°C, characteristic of weakly bound cations located on the external surface of the embryonic units, and another at higher temperature related to the size of OSDA. With a smaller OSDA, its decomposition is slower due to its confinement and more restricted access of the oxidant (O2) highlighted by a shift to higher temperatures (450°C in PTMA vs. 350°C in PTPA/THA). [START_REF] Chal | Overview and industrial assessment of synthesis strategies towards zeolites with mesopores[END_REF] C CP MAS NMR spectroscopy of the embryonic zeolites shows for each carbon frequency a superposition of a narrow signal and a large signal with a slight chemical shift. The narrow signals correspond to OSDA in less restricted environments, most probably located on the external surface of zeolite embryos, while the larger, correspond to OSDA in more confined environments, OSDA occluded into zeolite embryos, Figure S7. This is indicative of OSDA in two dif-ferent environments. [START_REF] Gittleman | A mechanistic study of the synthesis of zeolite SSZ-24[END_REF] The first sharp one belongs to mobile OSDA, most probably located on the external surface of zeolite embryos, while the second, broader, corresponds to OSDA located in a more confined space. This is consistent with the previously observed two exotherms on the DSC, namely: i) 200-250°C, OSDA in a loosely confined environment, ii) 250-500°C, OSDA in a more confined environment. Moreover, the [START_REF] Chal | Overview and industrial assessment of synthesis strategies towards zeolites with mesopores[END_REF] C CP MAS NMR of TPA + occluded in crystalline ZSM-5 has the distinctive splitting of its C3 (terminal methyl) peak attributed to the presence of two different environments (linear and zig-zag channels) in the zeolite channels. [START_REF] Boxhoorn | An investigation into the structure and position of organic bases in ZSM-5-type zeolites by highresolution solid-state 13 C nmr spectroscopy[END_REF][START_REF] Nagy | Position and configuration of the guest organic molecules within the framework of the ZSM-5 and ZSM-11 zeolites[END_REF] Such a splitting is not observed in PRT-TPA, indicating the presence of its methyl groups (C3) in a unique environment. A shift of -3 ppm of the C1 peak in the EZ indicates a more distorted angular configuration of its methylene group attached to the nitrogen as reported earlier. [START_REF] Dib | Preferential orientations of structure directing agents in zeolites[END_REF] Figure S8A shows the [START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] Al NMR spectra of all as-prepared samples, with a single peak centered at 53 ppm characteristic of tetrahedral aluminum. After calcination, Figure S8B, aluminum is present in other coordination: a majority remains in tetrahedral coordination (ca. 53 ppm), some become octahedral (0 ppm) and a broad peak (0 and -40 ppm) appears often attributed to distorted tetrahedral Al and/or penta-coordinated Al can be observed. The proportion of non-tetrahedral Al varies in the different samples. By deconvoluting the spectra using the dm-fit program, the relative fraction of octahedral aluminum is estimated between 38% (PRT-TMA) and 26% (PRT-THA), higher than the 10% usually observed for a pentasil type zeolite. However, this amount is substantially lower than what is observed in a variety of amorphous aluminosilicates. [START_REF] Welsha | High resolution 27Al NMR of amorphous silica-aluminas[END_REF] This indicates that a substantial portion of Al is stabilized in a silica matrix and remains there upon calcination at high temperature. The dealumination of zeolites depends on both the framework type and the T site within a given zeolite. [START_REF] Silaghi | Regioselectivity of Al-O Bond Hydrolysis during Zeolites Dealumination Unified by Brønsted-Evans-Polanyi Relationship[END_REF][START_REF] Karwacki | Architecture-dependent distribution of mesopores in steamed zeolite crystals as visualized by FIB-SEM tomography[END_REF] The larger proportion of octahedral Al is observed in the calcined PRT-TMA embryos and the lowest in PRT-THA; this could be related to the bond angles of the alumina-silica species surrounding the template, as the small TMA generates an inorganic network with more stress than the larger templates.

The acidity of embryonic samples is characterized by in-situ infrared spectroscopy using pyridine as a probe molecule. The number of BrØnsted acid sites (BAS) is calculated from the pyridinium band at 1545 cm -1 after the evacuation of pyridine at different desorption temperature. The results are given in Figure 6. The embryonic zeolites possess a significantly lower concentration (< 40 µmol. g -1 ) and strength of Brønsted acid sites in comparison to ZSM-5 (~ 135µmol.g -1 ), attributed to a wider distribution of angular configurations and organization of the alumino-silicate matrix compared to highly crystalline zeolites. After pyridine desorption at 150°C, the embryonic zeolites have slightly different concentrations of BAS, depending on the employed OSDA. Smaller OSDA leads to higher BAS concentrations (Figure 6B). An increase in the size/charge ratio of an OSDA leading to a decrease in the number of BAS was already reported by Barrer and Denny, [START_REF] Barrer | Hydrothermal chemistry of the silicates. Part X. A partial study of the field CaO-Al 2 O 3-SiO 2-H 2 O[END_REF] Aeillo and Denny [START_REF] Aiello | Hydrothermal chemistry of silicates. Part XIV. Zeolite crystallisation in presence of mixed bases[END_REF] and Kerr [START_REF] Kerr | Chemistry of crystalline aluminosilicates. II. The synthesis and properties of zeolite ZK-4[END_REF] for different zeolites. After desorption at a higher temperature (> 250°C), the number of Brønsted acid sites is close to zero for all samples, indicative of the low acid strength of the embryonic zeolites. By combining ICP-analysis and [START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] Al NMR results, it is possible to evaluate the amount of Al IV in each sample and, therefore the number of expected BAS. The Pyridine method account, however, fir only 20% of the expected amount of BAS. This might be due to the presence of BAS in a very confined environment inaccessible to pyridine or the remaining Al IV present in the calcined samples does not completely correspond to BAS. Indeed, the peak centered at 53 ppm in [START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] Al NMR is not symmetrical and presents an extension between 40 and 10 ppm, which can be attributed to highly distorted, tetrahedral, non-framework, aluminum-oxygen species. The chemical shift around 30 ppm is also consistent with penta-coordinated aluminum. [START_REF] Campbell | Dealumination of HZSM-5 zeolites: I. Calcination and hydrothermal treatment[END_REF][START_REF] Gilson | Penta-co-ordinated aluminium in zeolites and aluminosilicates[END_REF] In addition, during calcination, the tetrahedral symmetry of the lattice aluminum must be lost, and aluminum species of low symmetry formed. In a low symmetry environment, aluminum can become "invisible" due to important peak broadening of this quadrupolar nucleus. [START_REF] Klinowski | Monitoring of structural changes accompanying ultrastabilization of faujasitic zeolite catalysts[END_REF][START_REF] Fyfe | Investigation of the conversion (dealumination) of ZSM-5 into silicalite by highresolution solid-state silicon-29 and aluminum-27 MAS NMR spectroscopy[END_REF][START_REF] Maijanen | FT-IR and solid-state NMR investigation of surface hydroxyl groups on dealuminated ZSM-5[END_REF] The accessibility to active sites (B.A.S.) is best studied by infrared spectroscopy of adsorbed probe molecules of different kinetic diameters, namely Pyridine (0.57 nm) and Collidine (0.74 nm). [START_REF] Nesterenko | The use of the consecutive adsorption of pyridine bases and carbon monoxide in the IR spectroscopic study of the accessibility of acid sites in microporous/mesoporous materials[END_REF] The results of such experiments, performed under similar conditions, are summarized in Figure S9. The number of B.A.S is calculated from the bands associated with protonated pyridine (1545 cm -1 ) and collidine (1648 cm -1 ) after their adsorption and evacuation of the physisorbed portion of the adsorbates. The accessibility to B.A.S. is defined as the ratio between the number of B.A.S. measured by collidine and pyridine. While, with the TMA OSDA (PRT-TMA), the accessibility is 0.37, i.e. the sites probed by collidine are less than half of those probed by pyridine (13 µmol.g -1 vs 36 µmol.g -1 ), it becomes 1 when TPA is the OSDA (PRT-TPA). This indicates that all active sites are accessible to both molecules in the latter. So, in the presence of small OSDA, small pores are formed, restricting accessibility of their Brønsted acid sites to bulky molecules and leading to potential shape selective effects in embryonic zeolites. [START_REF] Lutterotti | Total pattern fitting for the combined sizestrain-stress-texture determination in thin film diffraction[END_REF] Si NMR spectra of as-synthesized and calcined embryonic zeolites prepared in the presence of the smallest (TMA), medium (TPA) and largest (THA) OSDAs show different silicon environments Q 2 , Q 3 and Q 4 (Figure S10). [START_REF] Boxhoorn | A highresolution solid-state29 Si nmr study of ZSM-5 type zeolites[END_REF] Their deconvolution with the dm-fit program gives the relative fraction of each species. After calcination, the chemical shifts are unchanged but the relative areas of Q 2 and Q 3 decrease while the Q 4 increase. These changes result from two simultaneous events upon heating: i) some tetrahedral Al changing coordination, ii) condensation of some silica species. The calcined samples have almost the same ratio of Q 3 and Q 4 species but the contribution of Al and OH groups to the Q 3 species differs between different samples.

Impact of temperature and synthesis time on the physicochemical properties of embryonic zeolites

In addition to room temperature synthesis, embryonic zeolites are prepared at 90°C during 12-216 h. As with the RT syntheses, all samples are freeze-dried before further processing and characterization.

The synthesis time is carefully controlled to obtain preformed units with only short-range order. Only the system containing TPA yields a crystalline phase (MFI-type) in syntheses longer than 24 h. The other systems are always amorphous after crystallization up to 216 h (Figure S11).

The [START_REF] Chal | Overview and industrial assessment of synthesis strategies towards zeolites with mesopores[END_REF] C CP MAS NMR of the TMA, TPA, and THA templates and the embryonic zeolites synthesized at RT and 90°C are displayed in Figure S7. All characteristic peaks of the template are present in the spectra of the embryonic zeolites. Peak broadening, an indication of the presence of the template in a confined environment, is observed.

Like the embryonic zeolites obtained at RT, the solids synthesized at 90°C exhibit a type I adsorption isotherm characteristic of a microporous material. In general, the materials synthesized at 90°C show an increase in nitrogen uptake with respect to their counterpart obtained at RT, Figure S12. This suggests a better structuring of these embryonic zeolites. The maximum micropore volume is achieved after different synthesis times for different templates. For instance, it is 12 h for a TPA synthesis and it decreases after 18 h, Figure S12B; this is related to the onset of crystallization of MFI. With TBA, there is no difference between 15 and 144 h, Figure S12C, while with TMAd the micropore volume increases up to 216 h of hydrothermal synthesis. The single exception is with THA, where the 90°C synthesis shows a lower pore volume and surface area (0.38 cm 3 .g-1 and 911 cm 2 .g-1) than its RT counterpart (0.47 cm 3 .g -1 and 1095 cm 2 .g -1 ), Figure S12E and Table S2.

It is difficult to determine the reason for such a trend but could be related to the large size of the THA molecule and a more efficient condensation of the aluminosilicate species at a higher temperature.

The effect of synthesis temperature on the state of Al in the embryonic zeolites is investigated by [START_REF] S-Aguiar | Cracking of 1, 3, 5-triisopropylbenzene over deeply dealuminated Y zeolite[END_REF] Al MAS NMR and IR monitored pyridine desorption. The 27 Al MAS NMR spectra of all as-synthesized samples exhibit a single peak (ca. 53 ppm) indicating the sole presence of tetrahedral aluminum, Figure S13. However, after calcination at 550°C, the intensity of this peak decreases, indicating that a portion of aluminum leaves its tetrahedral coordination. At the same time, two peaks emerge: a sharp and small at 0 ppm, typical for octahedrally coordinated aluminum, and a broad between 0 and -30 ppm, attributed to the presence of different polymorph of aluminum. Deconvolution of these spectra with the dm-fit program can evaluate the amount of nontetrahedral aluminum. The octahedral aluminum content decreases in the 90°C synthesis. The tetrahedral aluminum peak (53 ppm) is not symmetrical in all samples and tails between 40 and 10 ppm. As mentioned above, this can be attributed to the presence of highly distorted, tetrahedral, non-framework, aluminum-oxygen species or penta-coordinate aluminum.

IR spectroscopy of adsorbed pyridine measures the acidity of the embryonic zeolites. The number of Brønsted acid sites, calculated from the pyridinium ion band (1545 cm -1 ), are summarized in Table 1. The acidity of the EZ prepared at 90°C increases with synthesis time, but differences are marginal. As for the room temperature EZ syntheses, the smaller the OSDA, the higher the number of BAS; differences, however, are not substantial and all EZ possess a much lower number of acid sites than ZSM-5 with similar Si/Al ratio.

Catalytic activity

Earlier studies showed that amorphous zeolite precursors compelling catalytic performances in hydrocarbon conversion. [START_REF] Jacobs | Evidence for X-ray-amorphous zeolites[END_REF][START_REF] Bellussi | Amorphous mesoporous silica-alumina with controlled pore size as acid catalysts[END_REF] In the present work, we evaluated the catalytic performances of embryonic zeolites prepared at RT in the dealkylation of triisopropylbenzene (TiPBz), Figure 7A. Its kinetic diameter (0.95 nm), is well above the pore openings of the MFI-type zeolite (0.56 nm) and TiPBz is therefore com-monly used to study the external surface properties of zeolites, including the large pores (12 MR) ones. PRT-TMAd and PRT-TMA EZ lead to the highest and the lowest conversion, respectively, Figure 7A. Figure 7B highlights the effects of the OSDA on the conversion, number of Brønsted acid sites and micropore volume. While PRT-TMA possesses the highest number of Brønsted acid sites, its smallest conversion of TiPBz is related to the limited accessibility of its acid sites. This clearly indicates that the OSDA size is a tool to control the size selectivity of the EZ. For instance, TPA and TMAd generated materials comprise relatively strong Brønsted acid sites in micropores large enough to process TiPBz. Conversely, the larger TBA and THA OSDA generate EZ with larger micropores accessible to bulky molecules, but their catalytic performances are low due to a lack of Brønsted acid sites. Thus, EZ combining a critical number of active sites with pores opening large enough to transport the bulky TiPBZ display the best catalytic performances; the catalytic properties of embryonic zeolites can be tuned by accessibility and acid/active site density.

CONCLUSIONS

X-ray amorphous zeolite precursors, the so-called embryonic zeolites (EZ) are prepared with OSDA identical to those used in the synthesis of conventional zeolites. The synthesis conditions need to be controlled to obtain monodisperse suspensions of zeolite precursor particles with a size of a few nanometers. A thorough physicochemical characterization indicates that such zeolite precursors are highly uniform, and their properties strongly depend on the template used. All are microporous materials as the majority of their pores are in the range 1-2 nm. Some exhibit impressive specific surface area (1095 cm 2 .g -1 ) and micropore volume (0.47 cm 3 .g -1 ), larger than that of zeolites obtained with the same template. They are stable upon calcination and can be used as heterogeneous catalysts. While they possess a relatively low number of active sites of moderate acid strength, they display a high activity in bulky molecules conversion as their performance depends on and can be tuned by controlling their acidity and the accessibility of their active sites. EZ, therefore, extends the range of applications of current zeolites especially for bulky molecules; these are encountered in the processing of heavy oil fractions and biomass.

Figure 1 .

 1 Figure 1. The particle size distribution of PRT-TMA, PRT-TPA and PRT-THA suspensions.

Figure 1 .

 1 The size of embryonic zeolites depends on the size of the template employed and a clear relation is observed: maxima in the DLS peak of PRT-TMA, PRT-TPA, and PRT-THA are 2 nm, 3 nm and 4.5 nm respectively. The synthesis conditions are such that no material exhibits any long-range structural order, monitored by X-ray diffraction, FigureS1. An SEM inspection highlights a uniform mass of aggregated particles, FigureS2, at higher magnification, the grain-like structure of the particles building the aggregates appears. More information on the size and morphology of the embryon-ic zeolites was obtained by STEM-HAADF. Upon freezedrying, discrete particles are observed. Their size (3-5nm) matches well with the result of DLS analysis. The particles generally exhibit a spherical morphology with a rough surface most probably due to the presence of pores with diameters <0.9 nm as indicated by the arrows in the inset of Figure2B.

Figure 2 .

 2 Figure 2. Low (A) and high (B) magnification view of freeze-dried PRT-TPA sample and colloidal crystal (C left) made of uniform in size PRT-TPA zeolite embryos and a high magnification view of the arrays of EZ building the colloidal crystals (C right). Note: the white spots in the left image are gold particles employed for the alignments.

Figure 3 .

 3 Figure 3. XRD diagrams and Rietveld fits for (A) well crystallized (mean crystallite sizes are 133(10) nm; GoF = 1.9) and (B) embryonic samples (GoF = 1.2). Diagram bottoms are difference curves, insert in (B) is plotted in d-scale.

Figure 3

 3 Figure3shows the difference in XRD diagrams between fully crystallized and amorphous EZ prepared with TPA. While the fully crystallized powder (see Figure3A) clearly exhibits narrow diffraction peaks with cell parameters coherent with the original structure (a = 2.00484(7) nm; b = 1.99267(6) nm; c = 1.33919(5) nm), the amorphous sample (see Figure3B)

Figure 4 .

 4 Figure 4. N2 adsorption/desorption isotherms of PRT-SDA samples, where SDA is TMA, TPA, TMAd, TBA, and THA. The isotherm of nanosized ZSM-5 is included as a benchmark. The

  Low chemical shift peaks, close to 0 ppm, indicate large (meso-)pores, while high chemical shifts indicate more confined space (micro) pores. The NMR spectra of HP 129 Xe adsorbed on the PRT-TPA and PRT-THA samples recorded at different temperatures are shown in Figure5. In addition to the peak of xenon in the gas phase at 0 ppm, all spectra exhibit an additional resonance, which differs in PRT-TPA and PRT-THA samples. The PRT-TPA material exhibits a single peak (136-92 ppm) in the 200-320 K temperature range. The peak in PRT-THA sample shifts from 115 to 84 ppm in the 200-320 K temperature range. The higher chemical shift of Xe adsorbed in PRT-TPA can be attributed to xenon atoms located in a more confined environment. This result is in good agreement with the physisorption measurements showing that the large THA template generated EZ with substantially higher pore volume.

Figure 5 .

 5 Figure 5. NMR Spectra of HP 129 Xe adsorbed on PRT-TPA (A) and PRT-THA (B) samples recorded at variable temperature (200-320K).

Figure 6 .

 6 Figure 6. The number of Brønsted acid sites (µmol.g -1 ) for PRT-OSDA and nanosized ZSM-5 at different temperatures determined by TPD of pyridine (A) and at 150°C as a function of OSDA size (B).

Figure 7 .

 7 Figure 7. (A) TiPBz conversion of RT synthesized embryonic zeolites (A). (B) TiPBz conversion, number of BrØnsted acid sites and micropore volume of the embryonic zeolites as a function of OSDA in the synthesis. Catalytic test conditions: T = 300°C, WHSV = 8h-1, TOS = 2 min.

Table 1 . Number of Brønsted acid sites (µmol. g -1 ) of P-OSDA prepared at RT and at 90°C.

 1

	Embryonic	P-TMA		P-TPA			P-TMAd			P-TBA	P-THA	ZSM-5
	samples
	Temperature RT	P90-15 RT	P90-15 P90-18 RT	P90-15 P90-216	P90-15 P90-144	RT	P90-144
	150	32	34	27	35	38	20	40	37	23	20	11	22	135
	200	22	23	17	27	29	14	27	26	16	15	7	15	133
	250	14	12	6	18	18	8	15	15	8	7	3	7	128
	300	6	5	0	8	9	4	5	6	2	0	0	0	120
	350	3	1	0	2	2	2	2	1	0	0	0	0	105

Funding Sources

This research was supported by TOTAL Raffinage Marketing and the Industrial Chair ANR-TOTAL "Nanoclean Energy".

ASSOCIATED CONTENT

Supporting Information

The Supporting Information is available free of charge on the ACS Publications website at DOI: Characterization data: XRD, SEM, FTIR, N2 adsorption/desorption, Pore size distribution (DFT calculation), TG/DSC, NMR (pdf).

AUTHOR INFORMATION Corresponding Author

*E-mail : valentin.valtchev@ensicaen.fr

ORCID :

Mariame Akouche: 0000-0003-0490-7825 Valentin valtchev: 0000-0002-2341-6397

Author Contributions

All authors have given approval to the final version of the manuscript.

Notes

The authors declare no competing financial interest.

ACKNOWLEDGMENT

The financial support from TOTAL Raffinage Marketing and the Industrial Chair ANR-TOTAL "Nanoclean Energy". V.V. and S.M. acknoweldege the financial support from the CARNOT-ESP 3DNANOZET 5281. GENESIS is supported by the Région Haute-Normandie, the Métropole Rouen Normandie, the CNRS via LABEX EMC and the French National Research Agency as a part of the program "Investissements d'avenir" with the reference ANR-11-EQPX-0020. The authors appreciate the technical support of Marie Desmurs.