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A small-pore zeolite, Rho having 8-membered ring opening and 3-dimensional (3-D) channels is synthesized via a greener process, without the use of a structure-directing agent. The zeolite Rho is crystallized by a conventional hydrothermal reaction under static conditions. XRD pattern showed phase purity of RHO-type crystalline topology, and SEM images depicted polyhedral particles with bimodal size distribution. The average size of small and large sized particles are 200 nm and 1000 nm, respectively. The amount of total solid-acid sites on Rho zeolite is 2.534 mmol g−1 and BET specific surface area reached to 812 m2 g−1. The zeolite is tested for a gas-phase conversion of ethanol-to-ethylene in the temperature range of 200–400 °C. The catalytic efficiency and stability of Rho zeolite are compared with the materials extensively used in the dehydration of alcohols; a control zeolite (ZSM-5) and three different samples of γ-Al2O3. For ethanol dehydration under mild reaction conditions, the overall catalytic efficiency of Rho is superior to that of the ZSM-5 zeolite and the γ-Al2O3 materials. The strength and concentration of solid-acid sites are the main driving factors in the low-temperature dehydration of ethanol-to-ethylene.

Introduction of titanium into the frameworks of 14-ring extra-large-pore zeolites with CIT-5 (CFI-type, 7.2 × 7.5 A) and SSZ-53 (SFH-type, 6.4 × 8.7 A) topology has successfully been conducted by a chemical vapor deposition (CVD) method. The prepared titanosilicate zeolites have been characterized by XRD, SEM, UV–vis spectroscopy, IR spectroscopy, N2 adsorption, and elemental analysis. According to the characterization data, titanium is mostly incorporated into the framework of the zeolite in a tetrahedrally coordinated state. The catalytic epoxidation of cycloalkenes with H2O2 and tert-butyl hydroperoxide (TBHP) has been measured. The prepared titanosilicates with extra-large pores show superior performances for bulky molecule oxidation using TBHP as an oxidant compared to medium-pore TS-1 and large-pore Ti-beta.

We report here a simple way to prepare mesoporous silica materials with hydrophobic properties, as natural rubber (NR)/hexagonal mesoporous silica (HMS) nanocomposites, via an in situ sol-gel process using tetraethyl orthosilicate (TEOS) and decylamine as a silica precursor and organic template, respectively. Effects of swelling the NR sheet in TEOS, prior to dissolution in tetrahydrofuran, on the mesostructure, chemical composition and hydrophobicity of the resulting nanocomposites were investigated. The NR/HMS prepared with the pre-swelling step had superior structural and textural properties to that prepared without the pre-swelling step. The presence of rubber phase entrapped in the mesostructured silica and genuinely mesostructured NR/silica nanocomposite framework was confirmed by osmium tetroxide staining coupled with transmission electron microscopy analysis. The results obtained from X-ray photoelectron spectroscopy indicated a good dispersion of NR molecules in the mesostructured nanocomposites, which was determined by the distribution of non-hydrolyzed ethoxy groups. The use of toluene extraction, followed by characterization of the resulting material, identified the weak nature of the NR-silica interaction. Dynamic light scattering indicated that the presence of TEOS in the pre-swollen NR matrix enhanced the diffusion of template molecules into the rubber phase, and the dispersion of NR molecules in the synthesis mixture. Finally, a plausible mechanism for the formation of NR/HMS nanocomposites via cooperative templating route, in which the remnant ethoxy groups acted as hydrophobic linkers between the rubber chains and the silica oligomers, was proposed.

A series of MCM-68 zeolites with different Si/Al ratios were prepared by treatment with nitric acid and compared with beta zeolites. Speciation of aluminum and location of acid sites changed depending on the Si/Al ratio. The location of Bronsted acid sites in MCM-68 samples was able to be classified by FT-IR measurements with pyridine and 2,6-di-tert-butylpyridine as probe molecules, and the number of Bronsted acid sites was quantified according to the locations. For high-aluminum MCM-68, Bronsted acid sites were broadly distributed in both the 12-ring channel and 10-ring windows as well as inside the supercage. The Bronsted acid sites in the 12-ring channel were easily removed by the acid treatment, and consequently, high-silica MCM-68 had Bronsted acid sites predominantly in the 10-ring windows and inside the supercage. 27Al MQMAS NMR spectra of high-silica MCM-68 showed two specific peaks assignable to T6 and T7 sites, which did not face the 12-ring channel, forming the Bronsted acid sites highly toler...

Co-reaction of methanol and ethylene (CME) have been performed on a number of proton type MFI zeolites and CHA zeotype materials to investigate the influence of zeolite topology and acidities upon the transformation of reactants and the formation of desired product of propylene. Two other reactions of methanol-to-olefins (MTO) and ethylene transformation (ET, with only ethylene as the reactant) were carried out in order to compare the promotion effect for the propylene productivity. The reactions were carried out at 773 K. The addition of methanol remarkably promoted the ethylene transformation over Al-poor HMFI zeolite and, more importantly, the by-products due to hydrogen-transfer reactions were efficiently inhibited, leading to higher propylene selectivity. Such promotion effect was, however, not significantly observed upon the Al-rich HMFI zeolite. Moreover, such promotion effect of methanol upon ethylene transformation was un-pronounced or non-existed upon the CHA zeotype materials including aluminosilicate, gallosilicate and silicoaluminophosphate, possibly owing to the CHA topology.

Eight-membered ring small-pore zeolites Rho and KFI have been synthesized, characterized and tested for dehydration of methanol to dimethyl ether at low-temperature, and compared with other zeolites and three different samples of γ-Al2O3. Both the zeolites were mainly crystallized from the synthesis gels with the Si/Al ratio of 5.0 by a conventional hydrothermal method without any agitation. The amount of total solid-acid sites was 1.65 mmol g−1 and 2.53 mmol g−1 for zeolite KFI and Rho, respectively. In addition, zeolites SSZ-13, RUB-13, and ZSM-5 were also employed for the reaction. Reaction conditions were optimized for a low-temperature catalytic dehydration of methanol selectively to dimethyl ether. Methanol dehydration efficiency of various zeolitic frameworks is discussed against the strength of solid-acidity, type of channel structure, specific surface area, and particle size. At temperatures ≤ 200 °C, the overall catalytic efficiency of the small-pore zeolites with appropriate medium-strong acidity and 3-D channels was superior to that of the reference γ-Al2O3 materials.

Hierarchical zeolites become a research hotspot in the fields of zeolites and hetero-catalysis due to their improved utilization efficiency of micropores after introducing mesopores (2–50 nm). Here, a foam-like hierarchical zeolite comprised of many aggregated identical-lattice-direction hollow nanocrystals was firstly synthesized by selectively etching a pre-formed hierarchical zeolite, which achieved a new height in catalytic performance for olefin epoxidation.

The distribution of Al atoms in ZSM-5 has been recognized as an important factor in catalytic activity. Here, ZSM-5 zeolites were synthesized from synthetic gels containing various alcohols, including straight- and branched-chains alcohols. The effect of the alcohols in the synthetic gel on the Al distribution in the MFI framework was investigated based on 27 Al MAS NMR, Co(II) ion UV−vis DRS, and constraint index value. Thus synthesized ZSM-5 zeolites were applied to catalysts for the cracking of n -hexane and the methanol-to-olefins (MTO) reactions in order to investigate the impact of the Al distribution on the catalytic properties. A unique Al distribution in the MFI framework was achieved by the use of trimethylolethane (TME) in combination with Na cations, and thus-prepared ZSM-5 catalyst showed a long catalytic life for both the cracking of n -hexane and the MTO reaction.

Acid sites existing on the external surface of zeolites are the main cause of the formation of coke materials, resulting in decreasing the catalytic activity. For the durability of the reaction, silylation of external acid sites was adopted. Among various silylation reagents, cyclic siloxanes were effective silylation compounds for the deactivation of the acid sites on external surface on zeolite without prohibiting the objective reaction, cracking of naphtha. The effect of silylation was confirmed not only by the reaction but also by infra-red analysis.

Curbing anthropogenic CO2 emissions is one of the most important issues in the 21st century in order to mitigate climate change. Although the installation of solar cells for energy supply is in progress and these are becoming popular as an efficient use of sunlight, they are mostly used by energy-related industrial sectors. In the common chemical industry, various fossil resources are used to emit a huge amount of CO2. We believe that the chemical industry can make an effort to curb CO2 emissions by changing its resources to more environmentally benign ones. Solar hydrogen (hydrogen obtained by catalytic water splitting under sunlight) is an ideal sustainable resource and can be utilized as a chemical resource via combination with CO2. The 10 year program named “Artificial Photo Synthetic Chemical Process (ARPChem)” has been in progress under the support of the New Energy and Industrial Technology Development Organization (NEDO) in Japan since 2012. We introduce the strategy of ARPChem and the progress of the investigations including water splitting, hydrogen/oxygen separation, and olefin synthesis from solar hydrogen and CO2. We also argue that a realistic strategy to actualize “ARPChem” technologies in the society would be their combination with better fossil resources such as lower alkanes from a Life Cycle Assessment (LCA) point of view.

Although the characteristics of lithium–sulfur batteries are advantageous for various applications, batteries with liquid electrolytes show capacity fading due to the dissolution of polysulfides. All-solid-state lithium–sulfur batteries with highly reversible characteristics are developed using a three-dimensional carbon matrix framework structure for the sulfur cathode. Sulfur is introduced into a carbon replica framework with a pore size of 8–100 nm. The composite electrode structure provides high electronic conduction and allows high cathode utilization during the battery reaction. The capacity of cells using a LiAl alloy as the negative electrode and the thio-LISICON (lithium superionic conductor) electrolyte increases when the pore size of the carbon replica is decreased from 100 nm to less than 15 nm. The highest capacity is obtained for the carbon replica with a pore size of 8.6 nm and a wall thickness of 4.7 nm. An examination of the relationship between the charge–discharge capacity and the structure of carbon replicas with different pore sizes and wall thicknesses indicates that three-dimensional highly ordered mesoporous carbon with a small pore size is a promising electrode structure for lithium–sulfur all-solid-state batteries.

Hierarchically porous zeolites are a type of very hot catalyst with improved catalytic performances as compared with conventional microporous-only zeolites due to the improved mass transportation among the hierarchical meso/macropores, which are expected to be the next-generation catalysts for conversion of bulky molecules and/or polymers. Moreover, hierarchical zeolites with the single crystalline structure that is an identical registry of micropores within the entire particle identified the less pore blockage and less diffusion limitation compared to an aggregated structure of nano-zeolites. The developed synthetic methods were mostly conducted in a liquid-phase system and usually required expensive additives, such as silanes or mesoporogons, etc. Finding facile and cost-effective synthetic methods have been still challenging. Here, a facile and cost-effective strategy by controlling the growth/crystallization in a solidified hydrogel system was reported for the synthesis of Ti-containing MFI-type zeolites (TS-1) to simultaneously achieve hierarchical porosity, single-crystalline structure, and high catalytic performance in alkene oxidations. The synthesized zeolites were characterized by XRD, SEM, TEM, Nitrogen adsorption analysis, DRUV spectroscopy, IR spectroscopy, etc. The growth processes were also tracked and well-characterized. It was found that the solid-phase transformation mechanism was dominated for forming the hierarchical structure. This strategy could directly produce TS-1 with abundant intracrystalline continuous mesopores and large amounts of active framework titanium species, contributing to higher activity for epoxidation of alkenes compared to the traditional microporous-only TS-1 zeolites.

Titanosilicate molecular sieve (TS-1) is an important commercial catalyst for green production of oxyfunctionalized chemicals such as alcohols, ketones, epoxides, and oximes. Active TS-1 can normally be achieved in the synthetic media strictly free of alkali metal cations (e.g., Na + and K + ). This condition severely raises the purity demands of starting reagents, which greatly increases the production cost. Herein, we developed a method to achieve highly active titanosilicates in the presence of high-concentration alkali metal cations using anionic polymer-based quasi-neutral media. This synthetic route could effectively inhibit the adverse influence of alkali metal cations on the incorporation of active titanium(IV) sites into the framework of titanosilicate, directly affording the maximal framework titanium content (2.0 wt.%) with almost 100% yield. This development shows a great commercial potential and opens the possibility of preparing silica-based molecular sieves/zeolites in non-fluoride neutral media.

Propylsulfonic acid-functionalized natural rubber (NR)/hexagonal mesoporous silica (HMS) nanocomposites (NR/HMS-SO3H) with different acid contents were prepared via an in situ sol–gel process, and then applied as heterogeneous acid catalysts in the esterification of model carboxylic acids and palm fatty acid distillate (PFAD) with ethanol. The NR/HMS-SO3H composites exhibited a wormhole-like framework with enhanced wall thickness, high mesoporosity, and enhanced hydrophobicity. The NR/HMS-SO3H composites exhibited a superior catalytic performance compared to a commercial Nafion/silica composite solid acid catalyst (SAC-13) and conventional propylsulfonic acid-functionalized HMS (HMS-SO3H). The NR/HMS-SO3H catalyst can be regenerated and reused in the esterification.

Interlayer expansion using silylating agents to connect layer silicates to 3D framework structures has shown to be a versatile synthesis route to new crystalline, microporous frameworks. We demonstrate here that also Me cations can be introduced on the linker sites applying the same synthesis procedure. An acidic aqueous Fe-chloride solution was used in a hydrothermal reaction to convert the layered hydrous silicate precursor RUB-36 into an interlayer expanded zeolite, containing Fe at the linker sites, Fe-IEZ-RUB-36, Si 19.14 Fe 0.86 O 38 (OH) 4 . Structure analysis from powder X-ray data using the Rietveld technique confirmed that the porous framework is stable upon calcination and contains Fe on T-sites at the linker position. SEM–EDX analysis is in agreement with the analysis of the electron density maps showing that almost every other linker T-position is occupied by Fe-ions. The material crystallizes in the monoclinic space group Pm with a = 12.200(9) A, b = 13.981(8) A, c = 7.369(2) A, and β = 106.9(1)°. Applying a similar synthesis procedure, the Sn-analog, Sn-IEZ-RUB-36, Si 38.6 Sn 1.4 O 76 (OH) 8 , has been obtained and structurally characterized. Despite its limited crystallinity, Rietveld analysis of the PXRD data set confirmed the materials framework topology and chemical composition ( a = 23.856(14) A, b = 14.103(7) A, c = 7.412(7) A, in SG Pnm2 1 ). We conclude, that the synthesis procedure is flexible and, meanwhile, has been extended to other metal cations such as Ti, Zn, Eu and Al leading to microporous materials with potentially active metal cations on well defined sites of the silicate framework.

Titanium silicate-1 (TS-1) is a type of commercial titanium-containing Lewis acid zeolite used as a catalyst in environmentally-benign processes to produce epoxide from alkene. Activity, selectivity of targeted products and catalytic life are three key factors to evaluate the catalytic performance of the TS-1 catalyst. Here, we showed a highly active TS-1 catalyst and thereof low-cost synthetic method with the advantages of improving the active-titanium content, yield and reproducibility. The catalytic life is more than 360 minutes while only less than 20 minutes for TS-1 from conventional methods, leading to conversion of reactants more than twice as high as that of TS-1 synthesized by conventional methods. Both the conversion and catalytic life are the best among the current reported TS-1 zeolites for 1-hexene oxidation under similar reaction conditions.

This work deals with the dealumination of organic structure-directing agent (OSDA) free beta (OFB) zeolite by different methods to change its acid amount and enhance its catalytic performance in n-hexane cracking. The OFB zeolite was pre-treated with ammonium hexafluorosilicate (AHFS) solution, steaming, or concentrated NH 4 NO 3 ( ca. 10 M) followed by calcination at high temperature. Then, thus pre-treated OFB samples can be effectively dealuminated by acid treatment with the structure retained. The H-form OFB (HOFB) and dealuminated OFB (DOFB) catalysts were characterized by using X-ray diffraction, N 2 adsorption–desorption, SEM, ICP, NH 3 -TPD, 29 Si and 27 Al MAS NMR, and pyridine adsorption FT-IR. In the catalytic cracking of n-hexane, the DOFB catalysts showed a higher propylene selectivity and a longer catalytic life than the parent Al-rich HOFB catalyst. This would be attributed to the lower amount of acid sites, especially the Lewis acid sites, which suppressed the secondary reaction of propylene and butenes and the hydride transfer to form coke.

The catalytic cracking of n -hexane to selectively produce propylene on the MCM-22 catalysts dealuminated by nitric acid treatment was carried out as a model reaction of naphtha cracking. The nitric acid treatment of MCM-22 precursors under severe conditions followed by calcination at 823 K has been proven to be an effective dealumination method for MCM-22 zeolite. At a high n -hexane conversion of 90%, the dealuminated MCM-22 (D-MCM-22) catalyst with Si/Al = 34 showed a higher propylene selectivity (41 C-%) than H-ZSM-5 and H-Beta catalysts with similar acid amounts. Moreover, D-MCM-22 showed a stability comparable to H-ZSM-5 and much higher than H-Beta catalyst. This would be due to the selective removal of acid sites within supercages, suppressing coke formation and the resultant deactivation.

Sn-Beta was post-synthetically modified with various cations such as Li+, Na+, K+, Cs+, and NH4+. During the modification process, the ion-exchange of the cations with silanol groups occurred along with a reversible change between “closed” and “open” Sn sites through hydrolysis of the Si–O–Sn bonds. The IR study showed that Sn-Beta had weak Bronsted acid sites, which were passivated by the ion-exchange, in addition to the Lewis acid sites and that surprisingly, basic sites were formed on the modified zeolites. The ion-exchange with a small amount of Li+, Na+ and NH4+ was effective for suppressing side-reactions, leading to an improvement in selectivity to caprolactone in the Baeyer–Villiger oxidation of cyclohexanone with H2O2. The modification of Sn-Beta with such cations also effectively enhanced the catalytic activity in the Baeyer–Villiger oxidation of 2-adamantanone.

Zeolite TS-1 is an important commercial catalyst for green production of oxyfunctionalized chemicals such as alcohols, ketones, epoxides, and oximes. However, the extremely high price greatly restricts its wide applications. In this paper, we developed a new route to synthesize highly active TS-1 zeolites by using low-cost tetrapropylammonium hydroxide (TPAOH) as a starting reagent that contains alkali-metal cations such as Na+ and K+ and is much cheaper than the high-purity TPAOH currently used in reported routes. The key point is the introduction of a cation-exchange resin into the synthetic system to capture the alkali-metal cations via ion exchange between the alkali-metal cations in the synthetic medium and protons in the resin, as well as adjusting the pH value of the TS-1 synthetic system. The present development shows great commercial potential and opens the possibility of preparing cheap TS-1 catalysts by using commercial TPAOH raw materials.

The catalytic cracking of n-hexane for producing light olefins on Beta zeolite synthesized under organic structure-directing agent free conditions (OFB) was carried out as a model reaction of naphtha cracking. The Al-rich H-form OFB (HOFB) catalyst exhibited a short catalytic life and a low selectivity to propylene even at the lower reaction temperature of 773 K, due to its high acid amount. Dealumination of HOFB by ammonium hexafluorosilicate (AHFS) treatment and followed by nitric acid treatment resulted in the increase in the catalytic life and propylene selectivity, regardless of the reaction temperatures ranging from 773 to 923 K. This could be attributed to the lower amount of the acid sites especially the Lewis acid sites, which suppressed the secondary reactions of propylene and butenes and the hydride transfer to form coke. For example, the HOFB-AHFS(0.5 M)-HNO3(6 h) catalyst showed a very high selectivity of ca. 41 C-% to propylene even at nearly 100 % n-hexane conversion, at the higher reaction temperature of 923 K.

The use of pentaerythritol in combination with the Na cation in the synthesis of ZSM-5 led to a unique Al distribution in the MFI framework; Al atoms were preferentially located at straight and sinusoidal channels, not the intersection.

The layered silicate COK-5 has been used for an interlayer expansion reaction with dichlorodimethylsilane (DCDMS) at 180 °C to interconnect neighboring layers, yielding a new and crystalline microporous framework. The samples containing the methyl functional groups in the as-made form and having OH groups in the calcined form were designed as COE-5 and calcined COE-5. These samples were characterized with X-ray diffraction (XRD), N 2 sorption isotherms, inductively coupled plasma optical emission spectrometry (ICP-OES), infrared spectroscopy (IR), high-resolution transmission electron micrograph (HRTEM), thermogravimetry-differential thermal analysis (TG-DTA), and 29 Si and 13 C solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR), as well as the contact angle techniques. XRD patterns and HRTEM images suggest that the sample interlayer spacing has been expanded by nearly 0.5 A. The N 2 sorption isotherms of the materials show the BET surface areas are 165 m 2 /g for COE-5 and 340 m 2 /g for calcined COE-5. 29 Si and 13 C MAS NMR as well as IR spectroscopy confirm the insertion of the linker group -Si(CH 3 ) 2 - connecting neighboring layers. Interestingly, calcined COE-5 shows enhanced catalytic performance in the acetalisation of glycerol with acetone to produce solketal, compared with COK-5.

The catalytic cracking of n-hexane for producing propylene on MCM-22 catalysts was carried out as a model reaction of naphtha cracking. H-MCM-22 catalysts with different Si/Al ratios were prepared by direct or post-synthesis methods. The propylene selectivity was improved with an increase in the Si/Al ratio. Dealumination of H-MCM-22 with ammonium hexaflurosilicate (AHFS) (Del-Al-MCM-22) resulted in the increase in the catalytic life and propylene selectivity at a very high n-hexane conversion. This may be attributed to the decrease in the amount of Lewis acid sites which accelerate the hydride transfer and resultant coke formation. Del-Al-MCM-22 (Si/Al = 62) catalyst showed a high propylene selectivity (40 C-%) which was higher than H-ZSM-5 and H-Beta catalysts with similar Si/Al ratios at a high n-hexane conversion of 95%. Moreover, it showed a catalytic life comparable with H-ZSM-5 and longer than H-Beta catalyst.

Dehydration of sorbitol to isosorbide in water was studied using various types of aluminosilicate zeolites as heterogeneous catalyst. Among the zeolite catalysts tested, the *BEA-type aluminosilicate zeolite (beta) showed a remarkably high catalytic performance; especially, beta zeolite with the Si/Al ratio of 75, designated as beta(75), gave an isosorbide yield as high as 80%. We have found that the three-dimensional large pore structure is favorable for enhancing the diffusion of sorbitol and the products. In addition, beta with a low Al content exhibited a higher catalytic activity than that with a high Al content, despite the small number of acid sites. The reason for this high catalytic activity is ascribed to hydrophobicity of the catalyst surface. Hydrothermal stability is another critical factor in determining the catalytic performance. The influence of reaction parameters such as temperature and the catalyst amount was investigated. The beta(75) proved to be reusable without loss of activity after calcination at 550 °C.

The effect of the preparation conditions of the Ti-MWW catalyst on the hydrophobicity of the catalyst and its catalytic activity was investigated. Our findings demonstrated that the condensation of interlayer hydroxyl groups was greatly affected by the preparation conditions, in particular washing conditions of the as-synthesized lamellar precursor of Ti-MWW, then further controlling the final hydrophobicity and oxidation properties. Using organic solvents, especially EAOH, instead of water to wash the wet lamellar precursor would synchronize the interlayer hydroxyl condensation with the decrease of interlayer distance mainly caused by the leaching of piperidine, which was used as structure-directing agent (SDA). After acid-treatment, less SDA was kept in the EAOH washed sample and 3D-MWW with less defects was formed by calcination. Both drying temperature and acid-treatment would also affect the amount of SDA occluded in the interlayer void space of the acid-treated samples and then further affect the final interlayer hydroxyl condensation upon the following calcination. The lower both drying temperature and acid-treatment temperature were favorite to unequal interlayer dehydroxylation to form MCM-56, while higher drying temperature such as 150 °C not only caused the anatase phase in the calcined samples but also occluded more SDA molecules in the acid-treated samples which greatly affect the further interlayer hydroxyl condensation upon the calcination. Ti-MWW-OH-100 containing smallest amount of silanols and less defect sites showed the best hydrophobicity and the highest catalytic activity in 1-hexene oxidation.

The effects of the organic structure-directing agents (OSDAs) and Na cations for the synthesis of ZSM-5 on the location of Al atom in the framework as well as the acidic and catalytic properties were investigated. To achieve these purposes, ZSM-5 zeolites were synthesized by using four kinds of OSDAs including tetrapropylammonium hydroxide cations, dipropylamine, cyclohexylamine, and hexamethylenimine with or without Na cations. In situ FT-IR spectroscopy using CO as probe molecule was applied to the evaluation of the acid property of the ZSM-5 zeolites. The location of Al atoms was examined by high resolution 27Al MAS and MQMAS NMR techniques. The constraint index (CI) has also been used to estimate the distribution of acid sites in the micropores. The location of acid sites was investigated based on the difference in the transition-state shape-selectivity through the cracking of n-hexane and 3-methylpentane. Furthermore, the cracking of various types of paraffins and the conversion of aromatic compounds...

The CON-type aluminosilicate zeolites, which consist of a three-dimensional pore system with 12-, 12-, and 10-membered ring pores have been prepared by postsynthesis and the newly developed direct-synthesis methods. We first found that the CON-type aluminosilicate zeolites exhibited a higher catalytic performance in the methanol to olefins (MTO) reaction in terms of duration and propene selectivity than the MFI and *BEA-type aluminosilicate zeolites. They exhibited high propene selectivity, low ethene selectivity, and a very long catalytic life compared to Beta and ZSM-5; the selectivity for C3–C4 olefins reached 80%. Interestingly, the CON-type aluminosilicate zeolite synthesized by the direct-synthesis method showed a much longer catalytic lifetime than the one obtained by the postsynthesis method. The 27Al MAS and 27Al MQMAS NMR spectra suggest that there is a significant difference in the state of tetrahedrally coordinated Al species between the directly and postsynthesized zeolites, leading to the ma...