In Situ Assembly of Nanoparticles into Hierarchical Beta Zeolite with

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In Situ Assembly of Nanoparticles into Hierarchical Beta Zeolite with Tailored Simple Organic Molecule Kai Zhang, Zewei Liu, Xin Yan, Xuelong Hao, Min Wang, Chao Li, and Hongxia Xi Langmuir, Just Accepted Manuscript • DOI: 10.1021/acs.langmuir.7b03067 • Publication Date (Web): 17 Nov 2017 Downloaded from http://pubs.acs.org on November 18, 2017

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In Situ Assembly of Nanoparticles into Hierarchical Beta Zeolite with Tailored Simple Organic Molecule Kai Zhang,† Zewei Liu,† Xin Yan,† Xuelong Hao,‡ Min Wang,† Chao Li,*† and Hongxia Xi*† † School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Tianhe District, Guangzhou, China, 510641 ‡ National Center of Analysis and Testing for Non-ferrous Metals & Electronic Materials, General Research Institute for Nonferrous Metals, Beijing, China, 100088

ABSTRACT A hierarchically structured beta zeolite with intercrystalline mesopores was successfully synthesized via in situ assembly of nanoparticles by employing a simple organic molecule N2-pN2, tailored form polyquaternium surfactant, with no hydrophobic long chain. The generated samples were studied by using powder X-ray diffraction (XRD) and nitrogen adsorption/ desorption isotherms. Computer simulation, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) technologies were also used. The characterized results show that the tailored template molecule N2-p-N2 without hydrophobic long chain tail still can direct the zeolite crystallization, the hydrophobic long chain tail is not necessary during the mesoporous Beta zeolite formation. The catalytic performances of the sample were studied using alkylation of benzene with propene reaction to evaluate the relationship between the structure and property. The results apparently suggested that an overall improved resistance against deactivation compared with conventional beta zeolite in reactions. Furthermore, this tailored

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simple organic molecule strategy from dual-functional surfactant for making mesoporous zeolite would offer a new method of synthesizing other hierarchically structured zeolites.

INTRODUCTION The synthesis of hierarchical zeolites has attracted great attention in recent years, since the high crystalline mesoporous materials can integrate the positive features of microporous crystalline structure of zeolites (e.g. distinct pore dimensions, strong acidity, high hydrothermal stability and selective catalysis) as well as the advantage of mesoporosity.1-5 Industrially, hierarchical zeolites not only provide improved traditional catalytic properties, but also allow the extending of their applications to other emerging areas, such as nanomedicine, optoelectronics, chemical sensing, and so on.6-9 “Soft-templating” method is widely used to generate hierarchical zeolites, which usually involves the use of relatively flexible organic molecules such as polymers and surfactants playing the role of mesopore templates.10-12 In the past two decades, through this methodology, significant progress has been achieved in synthesizing hierarchical zeolites. Researchers from Mobil creatively synthesized a family of highly ordered mesoporous materials, M41S.13-15 These materials indeed provide more accessible active sites and faster mass transfer for large molecules. Unfortunately, intrinsic amorphous nature of the pore walls, such as weak acidity and poor stability, limited their practical applications. Many of the earlier methods of generating hierarchical zeolites often involved the use of ordinary organic surfactants and structuredirecting agents (SDAs, for example, short chain alkyl-ammonium salts). It was proved that it’s hard to synthesize crystalline zeolites containing micro- and mesoporous structures, simultaneously. Subsequently, the problems have been solved by appropriate choice of the

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organosilanes,16-17 cationic polymer

10-12

and dual-function poly-quaternary ammonium

surfactants.18-19 Ryoo et al. utilized an amphiphilic organosilane as the mesopore template to ZSM-5 zeolite with tunable mesoporosity.20 The amphiphilic organosilane templates are often constructed from a long-chain hydrophobic group and a hydrolysable alkoxysilane, such as ([(CH3O)3SiC3H6N+(CH3)2C16H33]Cl-: TPHAC). The long-chain hydrophobic group is assembling into mesoporous micelles and the hydrolysable alkoxysilane is participating in the crystallization of the zeolite and becoming part of its skeleton. The mesopore diameters are uniform and can be finely adjusted by changing the length of the hydrophobic chain of organosiloxane. This strategy was also employed to generate mesoporous aluminosilicate of LTA, BEA and FAU by using other either amphiphilic organosilanes.20-22 Hereafter, Choi and coworkers firstly designed a dual-functionalized molecule C22H45-N+(CH3)2-C6H12-N+(CH3)2C6H13 (C22-6-6) to synthesize single-cell thickness of the MFI layered nanosheets.23 The diquaternary ammonium head group directed the formation of the MFI zeolite, while the longchain tails “C22H45-” interacted with each other to restrict the excessive growth in a certain direction through formation of mesoscale micellar structure. On the basis of the former study, Na et al. applied a series of Gemini-type poly-quaternary ammonium surfactants (C18-N3-C18, C18N4-C18) to synthesize hexagonally ordered crystalline mesoporous zeolite materials, 2D heteronuclear correlation NMR revealed that the quaternary ammonium groups closely interacted with the aluminosilicate and were contained in the micropores.18 Recently, a new design of amphiphilic molecules composed of aromatic groups linked to the hydrophobic tail have been used to prepare single-crystalline MFI nanosheets successfully, the results could be interpreted as the π-π stacking in hydrophobic side. Furthermore, following the same strategy, aromatic groups were also introduced into bolaform and triply branched amphiphilic molecules to prepared a new

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type of MFI.24-26 In addition, A new material MIT-1 comprised of delaminated MWW zeolite nanosheets has been described by using an innovative designed organic structure-directing agent (OSDA) Ada-i-16,27 the OSDA has a hydrophobic tail and a hydrophobic head connected by a di-quaternary ammonium linker. In principle, all above mentioned strategies suggest long-chain hydrophobic tail is indispensable for the synthesis of hierarchical zeolites using soft-templating approaches. However, template synthesizing using these approaches is still a challenge because of wasting time, high cost and hard to control. Here, we present an efficient synthesis of highly crystalline hierarchical beta zeolite via the introduction of a tailored simple organic molecule (Figure 1) from polyquaternium surfactant N4phe.18 The tailored molecule (N(CH3)2-C6H12-N+(CH3)2-CH2-(p-C6H4)-CH2-N+(CH3)2-C6H12N(CH3)2[Cl-]2, abbreviated as N2-p-N2) contains no hydrophobic long chain tail. Unexpectedly, when it was used as a template, highly crystalline beta zeolite with intercrystalline mesopores was synthesized. Then, the growth process was intensively studied and the samples with different physico-chemical properties were obtained. The catalytic behavior was evaluated for an industrially-relevant chemical process, alkylation of benzene with propene, revealing significantly improved catalytic life time compared to commercially available conventional beta zeolite. In addition, hierarchical MTW with intercrystalline mesopores formed between nanoparticles can also be made through this method. Therefore, our results may provide a new pathway for the synthesis of zeolites with hierarchical structures.

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Figure 1. The molecular structure of the tailored simple organic molecule “N2-p-N2”, (hydrogen atoms are represented by white spheres, carbon atoms by gray ones and nitrogen atoms by blue ones). Counter anions (Cl-) in the molecule “N2-p-N2” are omitted. EXPERIMENTAL SECTION Synthesis of template and hierarchical beta zeolite. The tailored simple organic molecule used in this work is displayed in Figure 1 and was prepared according to the previous reports. Detailed synthesis procedure of N2-p-N2 is described as follows. 0.02 mol of α, αʹ-dichloro-p-xylene (98.0%, purchased from J&K Scientific) was mixed with 0.04 mol of N, N, Nʹ, Nʹ,-Tetramethyl-1,6-hexanediamine (99.0%, J&K Scientific), and then added to 75 ml acetonitrile/toluene mixture (isovolumic), and then put on a heating plate at 70 ℃ and dried for 20 h under magnetic stirring. After cooling down, the reaction mixture was collected and washed by filtration, and dried at 50 ℃ in a vacuum oven overnight, the final product Finally,

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[N(CH3)2-C6H12-N+(CH3)2-CH2-(p-C6H4)-CH2-N+(CH3)2-C6H12-N(CH3)2][Cl-]2.

C NMR measurements were taken place in CD3OD solution with a Bruker Avance

Digital 400 spectrometer to evaluate the purity of “N2-p-N2” molecule in Figure S1(a). Hierarchical beta zeolite was hydrothermally synthesized under base condition at 423 K with the molar ratio of OSDAs/SiO2/Al3O2/NaOH/H2O/EtOH=1.2:16:0.4:3.58:1143:128. In a typical synthesis, a homogeneous solution of 1.0 g of N2-p-N2 was dissolved in 24.55 g distilled water, and then, 0.189 g of NaAlO2, 3.6 g of EtOH and 0.29 g of NaOH were added quickly under stirring. After complete dissolution of the surfactant, 4.01 g TEOS was added to the solution to obtain the gel, then which was aged for 10 hours under vigorously stirring at 65 ℃. Afterwards, the resultant gel was transported into a 100 mL Teflon-lined stainless-steel autoclave and heated at 150 ℃ for 5 days with the autoclave set to tumbling at 60 r.p.m. After crystallization, the

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product was filtered, washed with distilled water and dried at 100 ℃ for 10 h in air condition. The product was calcined at 550 ℃ for 5 h under flowing air to remove the template. The resulting hierarchically structured beta zeolite was obtained and is denoted as H-Beta. The asmade H-Beta was also analyzed by 13C NMR measurements in the same conditions with “N2-pN2” molecule in Figure S1(b). For comparison, conventional beta was prepared by employing TEAOH as a template, and fumed silica was used as silica source, following the formerly reported synthesis process,19 and is denoted as C-Beta. The detailed synthesis procedure was described in the supporting information. Characterization. Powder X-ray diffraction (XRD) measurements were carried out with a Bruker D8 ADVANCE diffractometer equipped with a graphite monochromator, operating at 40 kV and 40 mA, and using Cu Kα radiation (wavelength λ = 0.1542 nm). Nitrogen adsorptiondesorption measurements were performed at 77 K using Micromeritics ASAP 2020 system, the specific surface areas were calculated by using the Brunauer-Emmett-Teller (BET) equation. The total pore volumes were obtained at P/P0 = 0.99, whereas the mesopore size distributions were determined by the Barrett-Joyner-Halenda (BJH) model, micropore surface areas and volumes were estimated by the non-local density function theory (NLDFT) method. Transmission electron microscopy (TEM) was taken by a JEM-2100HR electron microscope with an accelerating voltage of 200 kV. Scanning electron microscopy (SEM) were obtained with a Carl Zeiss, ZEISS Ultra 55 at a low landing energy (5.0 kV). Infrared spectra were collected on an FT-IR spectrometer (Bruker Vector 33), and the samples were tested in the form of KBr pellets with a resolution of 1 cm-1.

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Si and

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Al single pulse magic-Angle spinning (MAS) NMR

experiments were taken with a Bruker Avance AV 400 spectrometer at 104.26 MHz, 10 kHz, respectively. It was performed at magnetic fields of 16.50 and 16.04 T on spectrometer with the

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corresponding frequencies of 79.5 and 104.3 MHz and recovery delays 5 and 1 s, respectively. The spectra of 29Si were accumulated from 500 scans using a 4 mm probe with a sample amount of 150 mg, and 800 scans for 27Al spectra. Thermogravimetric measurements were performed on a Perkin Elmer Pyris 6 TGA analyzer at a heating rate of 5 ℃ min-1 in a N2 flow of 30 mL min-1. Calculations. Atomic behavior and molecular properties of small organic molecule were studied through density functional theory (DFT) calculations. The reactive abilities of the molecule are closely related to their frontier molecular orbitals (MO), and the lowest unoccupied molecular orbital (LUMO). Molecules geometry optimization were calculated at DFT B3LYP level theory (Beckeʹs three-parameter hybrid function and Lee-Yang-Parrʹs gradient-corrected correlation function) using the 6-31G* basis set with the Gaussian 03 program. Catalytic test. The alkylation of benzene with propene was taken up to evaluate the catalytic activities of generated H-Beta, which is carried out in a fixed bed microreactor at 240 ℃, the temperature was controlled by an electrical furnace. As a comparison, the conventional beta zeolite was also tested. Prior to the reactions, the zeolites were ion exchanged using 1 M aqueous NH4NO3 at 80 ℃ three times, and then all of which were converted to H+ form through calcination at 550 ℃ for 4 h in the air atmosphere. Flow rate of benzene to propene is 3 in mole ratio, a small flow of nitrogen was fed in order to improve the pressure control. The weigh hourly space velocity (WHSV) of benzene was 12 g h-1. The products were analyzed by gas chromatograph equipped with a flame ionization detector and separated by capillary column.

RESULTS AND DISCUSSION Material Characterization. The XRD peaks of the nanocrystalline beta zeolite samples generated by the tailored simple organic molecule N2-p-N2 is shown in Figure 2. Wide-angle X-

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ray diffractions show typical peaks at around 7.6° and 22.5°, which are consistent with characteristics of *BEA-type zeolite, suggesting the presence of the zeolite Beta crystals.28 However, comparing with the bulk counterpart, there is a significant degree of decrease in diffraction intensity for currently generated material. The phenomenon is owing to the formation of nano-sized particles,29 which then assembled in an irregular manner to possess the intercrystalline mesopores. These results demonstrate that simple organic molecule N2-p-N2 plays an important role in the generation of nanocrystalline zeolite beta material.

Figure 2. XRD patterns of C-Beta and H-Beta. FT-IR analysis was carried out to provide additional evidence for the generation of beta zeolite. Figure S2 shows that the asymmetrical stretching vibrations bands between 1050 and 1150 cm-1 are corresponding to the external linkage and internal tetrahedral atoms, and which are linear variable with the content of the framework aluminum atoms, thence the bands can be used to determine the changes in silicon and aluminum ratio.30 The structural vibrational band around 791 cm-1 can be belonging to symmetrical vibrations and internal tetrahedral symmetrical stretching of the external linkage. While the discriminate absorption appeared at 520 cm-1 and 575 cm-1 in the spectrum of Figure S2, implies the characteristic peaks of crystalline beta zeolite, and which are belonging to a vibration of T-O-T (T is Si or Al) from five or six membered rings.31 However, no peaks appear in this range with the crystallization time for 12 h in Figure 8


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S3, but they are gradually generated, and the intensity continuously increased with the extension of crystallization time from 24 h to 96 h, suggesting the crystallinity of beta zeolite is gradually increased, and which is consistent with XRD results in Figure S4. The displayed peaks around 420 cm-1 - 470 cm-1 are a Si-O bend, which can be detected in other SiO2 materials. SEM and TEM images of calcined H-Beta sample with different magnifications are shown in Figure 3 and Figure 4, H-Beta was composed of relatively uniform quasi-spherical particles with sizes in the range of 400 to 800 nm, and the quasi-spherical crystal was randomly assembled by crystallized rice-like nanoparticles with sizes in the range of 15 to 25 nm, significantly smaller than that of C-Beta with size about 1 µm (Figure S5), though they have similar initial Si/Al ratio of 15.6 for C-Beta to 17.5 for H-Beta. The high-resolution transmission electron microscopy (HRTEM) images show these rice-like nanoparticles exhibit lattice fringes with consistent orientations, and which were further identified by fast Fourier transform (FFT) diffractograms (inset Figure 4b) that they are single crystals. Then the aggregates of rice-like single-crystalline microporous nanoparticles assemble into a well crystallized mesoporous structure, which could be clearly observed from crystal morphologies (Figures 3a-c). The analysis suggests that each nanoparticle is a single crystal, while selected area electron diffraction (SAED) (left, inset Figure 4a) and corresponding FFT pattern (right, inset Figure 4a) of individual quasi-spherical crystal indicate polycrystalline structure. In addition, the characteristic stacking faults of the *BEA framework was obviously detected,

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suggesting two different orientations of micropores

correspond to two polymorphs, A and B (Figure 4c).

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Figure 3. SEM images of a, b and c are from calcined H-Beta samples, which are shown with different magnifications. The images of the samples were taken from pristine specimens without being coated.

Figure 4. TEM images of beta samples crystallized at 150 ℃ for 96 h. SAED pattern and the corresponding FFT diffractogram in (a) were taken from a quasi-spherical particle; FFT diffractogram in (b) was taken from beta nanoparticle; and inset in image c shows an intergrown crystal of both polymorph A and B. The coexistence of micropores and mesopores was determined by using micromeritics ASAP 2020 system. Figure 5a provides the nitrogen adsorption and desorption isotherms, exhibiting characteristics of type I and type IV, and which also show two steep steps due to the micropore filling in the region of P/P0 < 0.05 and capillary condensation in the mesopores in the 0.45 < P/P0 < 0.85 regions, respectively. The hysteresis loop of H1-type in Figure 5a indicates the interconnected mesopores and which do not restrict capillary evaporation of the adsorbed nitrogen. The microdiameters of H-Beta were calculated to be similar to that of C-Beta (0.64 nm,

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inset Figure 5b), while mesopore size was distributed in the range of 5 nm to 15 nm, and was centered at 10 nm. In comparison with C-Beta prepared by using tetraethylammonium cations, the crystallized H-Beta showed an obvious larger BET surface area (646 vs 532 m2g-1) and an apparently higher total pore volume (0.68 vs 0.28 cm3g-1) attributed to the contribution of mesopores. However, comparing with previously reported mesoporous beta zeolites directed by polyquaternium surfactant or cationic organic polymers that H-Beta showed smaller BET surface area (646 vs 870 m2g-1 for N6-diphe beta;18 646 vs 763 m2g-1 for Beta-MS12) and lower total pore volume (0.68 vs 1.14 cm3g-1 for N6-diphe beta;18 0.68 vs 0.89 cm3g-1 for Beta-MS12). On the other hand, H-Beta has considerable values with hierarchically structured beta with BET surface area 493-751 m2g-1 and total pore volume 0.46-0.99 cm3g-1, reported by Thomas Bein and coworkers by utilizing steam-assisted conversion (SAC) to induce a burst of nucleation.32 These analyses further proved the presence of mesopores in H-Beta zeolite. The hierarchical mesoporous network with large mesopore volume is firmly expected to reduce the diffusion path length and provide abundant external active sites for reactants, which are great significant for transmission performance when large molecules are involved.10, 12, 19, 23

Figure 5. (a) Nitrogen adsorption-desorption isotherms, and (b) pore size distributions of H-Beta and C-Beta zeolites.

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Si and 27Al NMR measurement results are shown in Figure 6. The 29Si NMR spectra revealed

the presence of two main peaks at around -111 and -114 ppm, both peaks were assigned to Q4 Si (4Si, 0Al) sites, and the difference can be directly correlated with the degree of silicon substitution by aluminum in the lattice.33-34 Other shifts were observed for the sample H-Beta, suggesting the additional chemical environments in the zeolite. The presence of peaks at -105 ppm, -103 ppm and -98 ppm corresponded to the species Q3 Si (3Si, 1Al), Q3 Si (3Si, 1OH), and Q2 Si (2Si, 2Al), respectively. These chemical shifts were due to the greater Al content in the HBeta, resulting in the creation of new environments around Si sites. Furthermore, shift of the peak between -104 ppm to 100 ppm was associated with Si/Al ratio, that is because the variable of the incorporation Si atoms from the type Q3 Si(3Si, 1Al), to Q3 Si(3Si, 1OH) or Q3 Si(3Si, 1O).35

Figure 6. (a) 29Si MAS NMR and (b) 27Al MAS NMR spectra of as-synthesized H-Beta. It is well known that

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Al MAS NMR spectroscopy provides information on the state of

aluminum in zeolites. Aluminum atoms in the zeolite framework is tetrahedral (AlTd) with a signal at 50-60 ppm while the extra framework aluminum atoms is in octahedral (AlOh) with a

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signal at ~0 ppm.36

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Al MAS NMR spectra of H-Beta exhibits only one signal at around 56.1

ppm assigned to (AlTd) atoms, while the (AlOh) atoms in the octahedral region at ~0 ppm cannot be seen. The result indicates all Al atoms are practically incorporated to the framework of HBeta zeolite, and the peak at around 56.1 ppm is corresponding to aluminum in positions T3-T9 sites.34 Figure S6 shows the thermogravimetric analysis of as-synthesized H-Beta. There three marked weight losses regions range of 35-150 ℃, 150-450 ℃ and 450-650 ℃. The first weight loss below 150 ℃ can be reasonably assigned to physically adsorbed water on the surface. The higher temperature weight loss between 150 ℃ and 450 ℃ is attributed to bonded water within the frameworks. While the main weight loss, which is approximate to 11.2 % in the initial synthetic gel, ranges of 450 ℃ to 650 ℃ corresponds to complete removal of simple organic molecule template incorporated in the framework of zeolite beta, formation of large pore volume and complex porosity in H-Beta sample. Hydrothermal stability of H-Beta has also been studied (Figure S7) by heating the zeolite in a 100% steam flow for 1 h at (a), 400 ℃; (b), 500 ℃ and (c), 600 ℃, respectively. The results indicate H-Beta still retained the crystalline zeolite structure and more than 60% of the initial tetrahedral Al (50-60 ppm) even after heated in 100% steam at 600 ℃. Investigation of the Formation Mechanism of H-Beta. As described above, N2-p-N2 is indeed an efficient SDA for the generation of H-Beta zeolite, and it played a role of bifunctional template in the synthesis process. To further understand the synthesis process of H-Beta, XRD, N2 adsorption-desorption isotherm, SEM, and TEM were carried out to investigate the intermediates at different generation periods. As exhibited by XRD, there were no crystals detected in the first 12 h, but the crystallinity was gradually increased with crystallization time

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from 36 h to 96 h (Figure S4). The SEM images (Figures 7a and 7b) show bulky quasi-spherical particles about 400-800 nm in size after crystallization for 12 h, and these particles are essentially amorphous according to the XRD. After 36 h, as shown in Figure 7c, the outer surface of amorphous samples began to split-up, and connected smaller nanoparticles can be clearly observed with the synthesis time was extended to 72 h (Figure 7e). Then smaller nanoparticles gathered together to form aggregates with similar size (400~800 nm) to the initial amorphous particles, and bulky quasi-spherical amorphous particles were missing, revealing that the H-Beta crystals nucleate from these bulky particles. With the extension of the crystallization time to 96 h, no significant changes were detected in SEM microstructure, while the XRD and IR spectrum imply characteristic peaks for high crystalline beta zeolite (Figure S3 and S4), indicating the amorphous particles were completely consumed, resulting in nanocrystals as the final products. However, SEM images of the grinded intermediates synthesized from 36 h to 72 h show gradually decreased bulky particles similar to the original amorphous particles, revealing the enhanced crystallinity and the reduced internal amorphous phase. However, the grinded samples synthesized for 96 h exhibit almost nanocrystals similar to the ones formed on the surface of the quasi-spherical particles, indicating that the sample was fully crystallized, which is consistent with the XRD result. According to TEM, the sample synthesized for 12 h was fully amorphous and it involved almost no pores structure (Figure 8a), suggesting no interaction between N2-p-N2 and aluminosilicate species in the initial phase. Tiny nanocrystals could be detected in the intermediate process synthesized for 36 h, and with the crystallization time extended to 72 h, more crystal grains were observed with the reduction of amorphous particles (Figures 8b and 8c), until they disappeared after crystallization for 96 h (Figure 8d), the

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phenomenon is consistent with SEM images of ground samples synthesized at different periods, and was also confirmed by N2 adsorption-desorption isotherms (Figure S8).

Figure 7. SEM images of calcined H-Beta samples crystallized at 150 ℃ for (a and b) 12 h, (c) 36 h, (e) 72 h, (g) 96 h and the calcined H-Beta samples after grinding (d) 36 h, (f) 72 h and (h) 96 h.

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Figure 8. TEM images of the grinding calcined H-Beta samples crystallized at 150 ℃ for (a) 12 h, (b) 36 h, (c) 72 h and (d) 96 h, respectively. The red arrows point to the small grains. Quaternary ammonium groups have been proved to be an effective template to direct the formation of conventional zeolite because of their adequate degrees of freedom. N2-p-N2 gives symmetrically distributed quaternary ammonium groups in a short flexible alkyl chain, and was used as SDA to generate hierarchical beta zeolite successfully. However, N2-p-N2 is a nonsurfactant, which cannot form mesostructure by self-assembling, the synthesized intercrystal mesopores are ordered distribution in morphology. Meanwhile, based on the formation process analyzed by means of XRD, SEM, TEM, and N2 adsorption-desorption isotherms, it is proposed that N2-p-N2 is well adsorbed on the surface of amorphous particles, and gradually reacted with aluminosilicate through consumption of surrounding amorphous agglomerates in the alkaline environments. Also, we detect the amount of organic template in the as made samples during different crystallization periods. The results are list in Table S2. The results show that the content of organic template in as made samples is basically the same to each other from 12 h to 96 h of crystallization, and is consistent with the weight loss of the template analyzed by

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thermogravimetric (Figure S6), indicating that the template has completely incorporated in the samples in the initial stage and maintained during the growth process. However, with the crystallization time prolonged, the amorphous particles do not start to crystalline as a whole, while it began to crystalline from the surface of the amorphous particle to inner part, and this behavior was demonstrated by SEM and TEM images taken from the samples crystallized for different periods (Figure 7 and 8). Based on these analyses that the inner templates of the amorphous particle do not react with aluminosilicate anions before the template on the surface react with aluminosilicate species in the presence of appropriate alkalinity in the liquid, resulting in intermesopores between the nanoparticles, thus the alkaline liquid can contact the inner template through the intermesopores, so that the inner template can continue to react with aluminosilicate species. Scheme 1 demonstrates the representation of the crystallization process. In the initial stage, the presence of Na+ competes with SDA+ for surface adsorption sites and increases the growth rate of the precursor particles, similar with the roles of TEA+ and Na+ in the synthesis of zeolite beta.37 The inner quaternary ammoniums of SDA+ on the amorphous surface preferred to interact with aluminosilicate anions gradually. With consumption of large amorphous particles, the surrounded crystallized nanoparticles gradually generated, and allowed it to be beta zeolite. Nucleation process on the outer surface of amorphous is accompanied by the formation of covalent bonds (T-O-T linkages, T=Si or Al) in the presence of SDA+, the extra SDA+ continues the same reaction with inner aluminosilicate species within amorphous particle until it is completely consumed. As the new nanocrystals generated, the SDAs+ are embedded into the aluminosilicate domain of zeolites, which is existing in the form of complete molecule N2-p-N2 (Figure S1). The nucleation process is in good consistent with the behavior of

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tetraethylammonium cations used as SDA to prepare zeolites, where OSDAs are either occluded in zeolites as an isolated cation or molecule geometrically fitted within the zeolite cavities.38-39 After crystallization, SDA was removed by calcination at 550℃ for 5h, resulting in beta zeolite with intercrystallite mesopores.

Scheme 1. The proposed mechanism for the synthesis of H-Beta using tailored simple organic molecule as the template. As proved in earlier studies, quaternary ammonium groups with intermediate hydrophobicity (C/N+ ratio) allow for structure-direction in the molecular sieve synthesis.38, 40 The small organic molecule used in this work contains no long-chain alkylammonium and is tailored from quaternary ammonium surfactant, which has been demonstrated successfully to prepared hierarchical zeolites. Hence, molecular properties and atomic behavior of the template can be theoretically investigated by density functional theory (DFT). Molecular electrostatic potential (MEP) is associated with electronic density and is widely employed in comprehending the active sites for electrophilic attack and nucleophilic reactions. As shown in Figure 9a, MEP was

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calculated under optimized geometry, showing that the positive regions distributed primarily within the inner ammonium groups, suggesting that the positively charged quaternary ammonium groups bonded directly to the rigid benzene ring is the preferred site for nucleophilic reactions.41 Lowest unoccupied molecular orbital (LUMO) of tailored small organic molecule is very important in defining activity, as shown in Figure 9b, which is associated with electron affinity and indicates the ability of the molecule to accept electrons42. LUMO is preferentially distributed within inner ammonium group, implying the reactive regions for nucleophilic attacks.43 The positively charged quaternary ammonium groups in the tailored small organic molecule can interact strongly with nucleophilic sites of anionic aluminosilicate species to stimulate zeolite-like surface structural ordering. These analyses real that the tailored small organic molecule can facilitate the interaction with anionic aluminosilicate species through the electrostatic force, which provides kinetics and accessibility of the templates to precursor used in the synthesis of zeolite Beta.

Figure 9. (a) Molecular electro static potential map, and (b) LUMO orbital density distribution of small organic molecule SDA (hydrogen atoms are represented by white spheres, carbon atoms by gray spheres and nitrogen atoms by blue spheres, respectively.)

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Catalytic performance. It has been proved that the hierarchical zeolites can overcome the diffusion limitations for large organic molecules. Here the catalytic life time of the H-Beta is the main concern. The alkylation of benzene with propene was chosen as a probe reaction, which has been certified that C-Beta can also catalyze the cumene synthesis reaction inside micropores owing to the molecular diffusion through the 12-MR apertures. As shown in Figure 10, in the first run, H-Beta and C-Beta samples exhibited nearly the same 81.5 % conversion of propene, suggesting that both H-Beta and C-Beta have similar acid strength distributions, which can be confirmed by NH3-TPD measurement (Figure S9). Though there is little less acid strength for HBeta than C-Beta (Table S1, Supporting Information), external acid sites play more contribution to the conversion for H-Beta. It can be seen that both H-Beta and C-Beta samples decrease the conversion of propene with the number of cycles, but C-Beta catalysts lost nearly 85% of its initial propene conversion after six recycling experiments. However, H-Beta catalyst still showed 45% propene conversion in six recycling experiments. The alkylation of benzene with propene involves short-chain olefins, which was thought to occur mainly inside zeolite channels. The prolonged catalytic life time of H-Beta can be attributed to abundant external active sites. On the one hand, fast transport to or out of the activated sites in mesopores can decrease the possibility of polymerization of by-products and leading to the formation of cokes;23 on the other hand, the result is owing to the catalytic deactivation kinetics,19, 44 kext ≤ kint (k is the deactivation rate constant, the subscripts “ext” and “int” refer to the external and internal sites, respectively.), meaning the external catalytic sites deactivated much more slowly than the internal sites in hierarchical zeolites.

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Figure 10. Catalytic activities of H-Beta and C-Beta samples for the conversion of alkylation of benzene with propene. CONCLUSIONS A hierarchical Beta zeolite was successfully generated by employing a tailored simple organic molecule “N2-p-N2” without any hydrophobic long alkyl tail groups as a dual-function template. Nitrogen adsorption/desorption measurements demonstrated that the H-Beta possessed higher surface area and larger mesopore volume than C-Beta. SEM/TEM images show that the H-Beta sample is composed of relatively uniform quasi-spherical particles with sizes ranging from 400 to 800 nm, and which is randomly assembled by crystallized rice-like nanoparticles with sizes in the range of 15 to 25 nm. Synthesizing process indicates that H-Beta zeolite was crystallized from outer surface of quasi-spherical particle to inside through in situ consumption of amorphous silicon and aluminum species. In addition, the H-Beta shows greatly improved potential catalytic performance in the alkylation of benzene with propene reaction, and which can also be generally applicable as a new way of designing SDAs for hierarchical zeolite synthesis, such as hierarchical MTW zeolite (Figure S10).

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ASSOCIATED CONTENT Supporting Information.

13

C MAS NMR spectrums of N2-p-N2 and its corresponding as-made

zeolite H-Beta. IR spectra of C-Beta and H-Beta samples, IR spectra of skeletal vibration of generated H-Beta zeolites in different crystallization time. Influences of the crystallization time on the generation of H-Beta zeolite. TEM images of C-Beta at different magnifications. Thermogravimetric curve and hydrothermal stability of the obtained hierarchically Beta framework. Nitrogen adsorption-desorption isotherms and pore size distributions, NH3 temperature-programmed desorption profiles, data of H-MTW were determined and shown in SI. This material is available free of charge via the Internet at http://pubs.acs.org.

ACKNOWLEDGEMENTS This work was supported by the National Natural Science Foundation of China (No. 21436005 and No. 21576094), the National High Technology Research and Development Program of China (No. 2013AA065005), SRFDP (No. 20130172110012), Guangdong Natural Science Foundation (S2011030001366), and the Fundamental Research Funds for the Central Universities (No. 2017MS031) to whom we are all gratefully acknowledged.

AUTHOR INFORMATION Corresponding Authors Tel.: +86 20 87113501; Fax: +86 20 87113735 *

Emails: [email protected] (Chao Li); [email protected] (Hongxia Xi)

Notes The authors declare no competing financial interest.

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REFERENCES (1) Mukti, R. R.; Hirahara, H.; Sugawara, A.; Shimojima, A.; Okubo, T., Direct Hydrothermal Synthesis of Hierarchically Porous Siliceous Zeolite by Using Alkoxysilylated Nonionic Surfactant. Langmuir 2009, 26 (4), 2731-2735. (2) Corma, A.; Diaz-Cabanas, M. J.; Jorda, J. L.; Martinez, C.; Moliner, M., High-throughput synthesis and catalytic properties of a molecular sieve with 18- and 10-member rings. Nature 2006, 443 (7113), 842-845. (3) Li, K.; Valla, J.; Garcia-Martinez, J., Realizing the Commercial Potential of Hierarchical Zeolites: New Opportunities in Catalytic Cracking. ChemCatChem 2014, 5 (1), 46-66. (4) Xu, L.; Sun, J., Recent Advances in the Synthesis and Application of Two-Dimensional Zeolites. Adv. Energy Mater. 2016, 6 (17), 1600441. (5) Hartmann, M.; Machoke, A. G.; Schwieger, W., Catalytic test reactions for the evaluation of hierarchical zeolites. Chem. Soc. Rev. 2016, 45 (12), 3313-3330. (6) Martínez, C.; Corma, A., Inorganic molecular sieves: Preparation, modification and industrial application in catalytic processes. Coord. Chem. Rev. 2011, 255 (13-14), 1558-1580. (7) Mintova, S.; Jaber, M.; Valtchev, V., Nanosized microporous crystals: emerging applications. Chem. Soc. Rev. 2015, 44 (20), 7207-7233. (8) Wang, Z.; Yu, J.; Xu, R., Needs and trends in rational synthesis of zeolitic materials. Chem. Soc. Rev. 2012, 41 (5), 1729-1741. (9) Yang, G.; Wei, Y.; Xu, S.; Chen, J.; Li, J.; Liu, Z.; Yu, J.; Xu, R., Nanosize-Enhanced Lifetime of SAPO-34 Catalysts in Methanol-to-Olefin Reactions. J. Phys. Chem. C 2013, 117 (16), 8214-8222. (10) Xiao, F.-S.; Wang, L.; Yin, C.; Lin, K.; Di, Y.; Li, J.; Xu, R.; Su, D. S.; Schlögl, R.; Yokoi, T.; Tatsumi, T., Catalytic Properties of Hierarchical Mesoporous Zeolites Templated with a Mixture of Small Organic Ammonium Salts and Mesoscale Cationic Polymers. Angew. Chem. Int. Ed. 2006, 45 (19), 30903093. (11) Wang, R.; Liu, W.; Ding, S.; Zhang, Z.; Li, J.; Qiu, S., Mesoporous MFI zeolites with self-stacked morphology templated by cationic polymer. Chem. Commun. 2010, 46 (39), 7418-7420. (12) Zhu, J.; Zhu, Y.; Zhu, L.; Rigutto, M.; van der Made, A.; Yang, C.; Pan, S.; Wang, L.; Zhu, L.; Jin, Y.; Sun, Q.; Wu, Q.; Meng, X.; Zhang, D.; Han, Y.; Li, J.; Chu, Y.; Zheng, A.; Qiu, S.; Zheng, X.; Xiao, F.-S., Highly Mesoporous Single-Crystalline Zeolite Beta Synthesized Using a Nonsurfactant Cationic Polymer as a Dual-Function Template. J. Am. Chem. Soc. 2014, 136 (6), 2503-2510. (13) Beck, J. S.; Vartuli, J. C.; Roth, W. J.; Leonowicz, M. E.; Kresge, C. T.; Schmitt, K. D.; Chu, C. T. W.; Olson, D. H.; Sheppard, E. W., A new family of mesoporous molecular sieves prepared with liquid crystal templates. J. Am. Chem. Soc. 1992, 114 (27), 10834-10843.

23


Page 25 of 27

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(14) Wang, L.; Shao, Y.; Zhang, J., Short-time formation of well-ordered cubic mesoporous MCM-48 molecular sieve with the aid of fluoride ions. Mater. Lett. 2005, 59 (28), 3604-3607. (15) Bagshaw, S. A.; Prouzet, E.; Pinnavaia, T. J., Templating of Mesoporous Molecular Sieves by Nonionic Polyethylene Oxide Surfactants. Science 1995, 269 (5228), 1242-1244. (16) Zhu, H.; Abou-Hamad, E.; Chen, Y.; Saih, Y.; Liu, W.; Kumar Samal, A.; Basset, J.-M., Organosilane with Gemini-Type Structure as the Mesoporogen for the Synthesis of the Hierarchical Porous ZSM-5 Zeolite. Langmuir 2016, 32 (8), 2085-2092. (17) Rioland, G.; Albrecht, S.; Josien, L.; Vidal, L.; Daou, T. J., The influence of the nature of organosilane surfactants and their concentration on the formation of hierarchical FAU-type zeolite nanosheets. New J. Chem. 2015, 39 (4), 2675-2681. (18) Na, K.; Jo, C.; Kim, J.; Cho, K.; Jung, J.; Seo, Y.; Messinger, R. J.; Chmelka, B. F.; Ryoo, R., Directing Zeolite Structures into Hierarchically Nanoporous Architectures. Science 2011, 333 (6040), 328-332. (19) Kim, W.; Kim, J.-C.; Kim, J.; Seo, Y.; Ryoo, R., External Surface Catalytic Sites of SurfactantTailored Nanomorphic Zeolites for Benzene Isopropylation to Cumene. ACS Catal. 2013, 3 (2), 192-195. (20) Choi, M.; Cho, H. S.; Srivastava, R.; Venkatesan, C.; Choi, D.-H.; Ryoo, R., Amphiphilic organosilane-directed synthesis of crystalline zeolite with tunable mesoporosity. Nat. Mater. 2006, 5 (9), 718-723. (21) Cho, K.; Cho, H. S.; de Ménorval, L.-C.; Ryoo, R., Generation of Mesoporosity in LTA Zeolites by Organosilane Surfactant for Rapid Molecular Transport in Catalytic Application. Chem. Mater. 2009, 21 (23), 5664-5673. (22) Inayat, A.; Knoke, I.; Spiecker, E.; Schwieger, W., Assemblies of Mesoporous FAU-Type Zeolite Nanosheets. Angew. Chem. Int. Ed. 2012, 51 (8), 1962-1965. (23) Choi, M.; Na, K.; Kim, J.; Sakamoto, Y.; Terasaki, O.; Ryoo, R., Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts. Nature 2009, 461 (7261), 246-249. (24) Xu, D.; Jing, Z.; Cao, F.; Sun, H.; Che, S., Surfactants with Aromatic-Group Tail and Single Quaternary Ammonium Head for Directing Single-Crystalline Mesostructured Zeolite Nanosheets. Chem. Mater. 2014, 26 (15), 4612-4619. (25) Xu, D.; Ma, Y.; Jing, Z.; Han, L.; Singh, B.; Feng, J.; Shen, X.; Cao, F.; Oleynikov, P.; Sun, H.; Terasaki, O.; Che, S., π-π interaction of aromatic groups in amphiphilic molecules directing for singlecrystalline mesostructured zeolite nanosheets. Nat. Commun. 2014, 5 (4262), 1-9. (26) Zhang, K.; Li, C.; Liu, Z.; Wang, M.; Yan, X.; Xi, H., Tailoring Hierarchical Zeolites with Designed Cationic Surfactants and Its High Catalytic Performance. Chem. Asian J. 2017, 12 (20), 2711– 2719.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 27

(27) Luo, H. Y.; Michaelis, V. K.; Hodges, S.; Griffin, R. G.; Roman-Leshkov, Y., One-pot synthesis of MWW zeolite nanosheets using a rationally designed organic structure-directing agent. Chem. Sci. 2015, 6 (11), 6320-6324. (28) Zhang, K.; Liu, Z.; Wang, M.; Yan, X.; Li, C.; Xi, H., Synthesis and catalytic performance of hierarchically structured beta zeolites by a dual-functional templating approach. New J. Chem. 2017, 41 (10), 3950-3956. (29) Möller, K.; Yilmaz, B.; Müller, U.; Bein, T., Hierarchical Zeolite Beta via Nanoparticle Assembly with a Cationic Polymer. Chem. Mater. 2011, 23 (19), 4301-4310. (30) Guisnet, M.; Ayrault, P.; Coutanceau, C.; Fernanda Alvarez, M.; Datka, J., Acid properties of dealuminated beta zeolites studied by IR spectroscopy. J. Chem. Soc., Faraday Trans. 1997, 93 (8), 16611665. (31) Ikuno, T.; Chaikittisilp, W.; Liu, Z.; Iida, T.; Yanaba, Y.; Yoshikawa, T.; Kohara, S.; Wakihara, T.; Okubo, T., Structure-Directing Behaviors of Tetraethylammonium Cations toward Zeolite Beta Revealed by the Evolution of Aluminosilicate Species Formed during the Crystallization Process. J. Am. Chem. Soc. 2015, 137 (45), 14533-14544. (32) Möller, K.; Yilmaz, B.; Jacubinas, R. M.; Müller, U.; Bein, T., One-Step Synthesis of Hierarchical Zeolite Beta via Network Formation of Uniform Nanocrystals. J. Am. Chem. Soc. 2011, 133 (14), 52845295. (33) Hajjar, R.; Millot, Y.; Man, P. P.; Che, M.; Dzwigaj, S., Two Kinds of Framework Al Sites Studied in BEA Zeolite by X-ray Diffraction, Fourier Transform Infrared Spectroscopy, NMR Techniques, and V Probe. J. Phys. Chem. C 2008, 112 (51), 20167-20175. (34) Fyfe, C. A.; Thomas, J. M.; Klinowski, J.; Gobbi, G. C., Magic-Angle-Spinning NMR (MASNMR) Spectroscopy and the Structure of Zeolites. Angew. Chem. Int. Ed. 1983, 22 (4), 259-275. (35) Mintova, S.; Valtchev, V.; Onfroy, T.; Marichal, C.; Knözinger, H.; Bein, T., Variation of the Si/Al ratio in nanosized zeolite Beta crystals. Microporous Mesoporous Mater. 2006, 90 (1–3), 237-245. (36) Hu, J. Z.; Wan, C.; Vjunov, A.; Wang, M.; Zhao, Z.; Hu, M. Y.; Camaioni, D. M.; Lercher, J. A., 27Al MAS NMR Studies of HBEA Zeolite at Low to High Magnetic Fields. J. Phys. Chem. C 2017, 121 (23), 12849-12854. (37) Hould, N. D.; Foster, A.; Lobo, R. F., Zeolite beta mechanisms of nucleation and growth. Microporous Mesoporous Mater. 2011, 142 (1), 104-115. (38) Kubota, Y.; Helmkamp, M. M.; Zones, S. I.; Davis, M. E., Properties of organic cations that lead to the structure-direction of high-silica molecular sieves. Microporous Materials 1996, 6 (4), 213-229. (39) Moliner, M.; Rey, F.; Corma, A., Towards the Rational Design of Efficient Organic StructureDirecting Agents for Zeolite Synthesis. Angew. Chem. Int. Ed. 2013, 52 (52), 13880-13889.

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Page 27 of 27

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(40) Goretsky, A. V.; Beck, L. W.; Zones, S. I.; Davis, M. E., Influence of the hydrophobic character of structure-directing agents for the synthesis of pure-silica zeolites. Microporous Mesoporous Mater. 1999, 28 (3), 387-393. (41) Kaya, S.; Kaya, C., A new method for calculation of molecular hardness: A theoretical study. Comput. Theor. Chem. 2015, 1060, 66-70. (42) Obot, I. B.; Macdonald, D. D.; Gasem, Z. M., Density functional theory (DFT) as a powerful tool for designing new organic corrosion inhibitors. Part 1: An overview. Corros. Sci. 2015, 99, 1-30. (43) Laurent, A. D.; Jacquemin, D., TD-DFT benchmarks: A review. Int. J. Quantum Chem. 2013, 113 (17), 2019-2039. (44) Corma, A.; Martı́nez-Soria, V.; Schnoeveld, E., Alkylation of Benzene with Short-Chain Olefins over MCM-22 Zeolite: Catalytic Behaviour and Kinetic Mechanism. J. Catal. 2000, 192 (1), 163-173.

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