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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.

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.

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.

The reaction mechanism of all-solid-state lithium–sulfur batteries was studied by small- and wide-angle X-ray scattering. The results revealed that sulfur deposited in the electrode framework has a random distribution on the carbon wall of the highly ordered mesoporous carbon, CMK-3. Heat treatment complicated carbon surfaces with attached sulfur and improved the reversible charge–discharge reaction. Two Li 2 S phases formed during the discharge reaction; one of them participates in the reversible battery reactions.

Microporous cesium salts of modified and unmodified tetravalent Keggin-type polyoxometalates, including Cs-4[SiW12O40], Cs-4[PW11O39(Sn-n-C4H9)], and Cs-4[PW11O39(Sn-OH)], were synthesized. The crystalline structures, which had body-centered cubic (bcc) arrangements, the lattice constants, and the pore-size distributions of the three Cs salts were similar, regardless of the presence or absence and types of functional groups introduced. The Cs salts had only micropores and no mesopores. The micropore size distributions were determined from adsorption isotherms of Ar, which showed a sharp peak at 0.59 nm and a shoulder at 0.62 nm. The fractions of the external surface areas to the total surface areas of the Cs salts were less than 6%. It is plausible that the micropores originate from the heteropoly anion defects in the crystallite, which form to avoid mismatches in the Cs+/(heteropoly anion) ratio required for charge balance (=4) and for a bcc structure (=3). The surface of the Cs salt introduced with n-butyl groups was hydrophobic, although the surface density of the n-butyl groups was low. On the other hand, the hydroxyl groups present on the surface of Cs-4[PW11O39(Sn-OH)] had little effect on the adsorption of water, methanol, ethanol, and hexane but a great impact on that for benzene due to the interactions between the -OH groups and the aromatic rings (-OH center dot center dot center dot pi). (C) 2013 Elsevier Inc. All rights reserved.

Catalytic cracking of n-hexane to selectively produce propylene on Beta zeolite was carried out. The H-Beta (HB) (Si/Al = 77) zeolite showed higher catalytic stability and propylene selectivity than the Al-rich HB (Si/Al = 12), due to its smaller number of acid sites, especially Lewis acid sites (LAS). However, catalytic stability and propylene selectivity in high n-hexane conversions were still not satisfactory. After dealumination with HNO3 treatment, catalytic stability was improved and propylene selectivity during high n-hexane conversions was increased. On the other hand, catalytic stability was not improved after desilication with NaOH treatment, although mesopores were formed. This may be related to the partially destroyed structure. However, propylene selectivity in high n-hexane conversions was increased after alkali treatment. We successfully found that the catalytic stability was improved and the propylene selectivity in high n-hexane conversions was further increased after the NaOH treatment followed by HNO3 treatment. This is due to the decrease in the number of acid sites and the increase in mesopores which are beneficial to the diffusion of coke precursor.

A high-capacity type of all solid-state battery was developed using sulfur electrode and the thio-LISICON electrolyte. New nano-composite of sulfur and acetylene black (AB) with an average particle size of 1–10 nm was fabricated by gas-phase mixing and showed a reversible capacity of 900 mAh g −1 at a current density of 0.013 mA cm −2 .

Carbonization of d-glucose at 573−723 K followed by sulfonation produces a functionalized amorphous carbon material with acid catalytic activity as a solid-acid replacement for sulfuric acid. The carbon material contains phenolic hydroxyl, carboxylic acid, and sulfonic acid groups and exhibits high catalytic performance for liquid-phase acid-catalyzed reactions. Carbonization at higher temperature followed by sulfonation also results in amorphous carbon, but the resultant does not exhibit catalytic activity although the amorphous carbon has sufficient amount of sulfonic acid groups. Structural and active site analyses suggest that the marked difference in catalytic activity is due to the accessibility of reactants to sulfonic acid groups in the carbon structure.

A novel strategy for the synthesis of microporous crystalline titanosilicate catalyst (TS-1) was developed based on the combination of liquid-phase and solid-phase transformation mechanisms. The core concept of this strategy was to crystallize the mixed precursors composed of both liquid-phase and solid-phase precursors. The anionic polyelectrolyte poly(acrylic acid) was used as a unique gelating agent to prepare the solid/liquid mixture, which can partly convert the liquid-phase precursor to the solid-phase precursor. Active framework Ti was formed by in situ conversion of the Ti species from the solid-phase precursor during the crystallization stage, as well as by the transfer of Ti species from the liquid-phase precursor to the solid crystal after the crystallization. In this way, the content of active Ti in TS-1 was significantly increased. The obtained product displayed high activity for the oxidation reaction of n-hexane and 1-hexene.

A novel titanosilicate with MWW topology, Ti-MWW, has been prepared by an acid treatment on a corresponding lamellar precursor which is hydrothermally synthesized with the coexistence of boron and titanium using piperidine (PI) or hexamethyleneimine (HM) as a structure-directing agent. The MWW precursor can be synthesized to have a Si/Ti ratio as low as 10 when the Si/B ratio of the gel is maintained at 0.75. Both the materials synthesized using PI and HM exhibit the crystal form of thin platelets, while the latter shows a larger crystal size. Besides the tetrahedral Ti species, the precursor always contains the octahedral Ti species showing a UV−vis band at 260 nm, regardless of the Ti content. Calcination of the precursor results in a partial condensation of the octahedral Ti species to form the anatase phase, which is hardly removed by the acid treatment. MWW-type titanosilicate nearly free of both anatase and boron, however, is successively prepared by a cyclic treatment on the lamellar precursor, tha...

The catalytic properties of Ti–MWW catalysts have been studied for the oxidation of alkenes using hydrogen peroxide or tert -butyl hydroperoxide (TBHP) as an oxidant. Ti–MWW shows superior activity independent of the nature of oxidant when compared to the other Ti-containing catalysts both of microporous TS-1 and Ti-MOR and of mesoporous Ti–MCM-41 in the oxidation of cyclohexene. Compared to large-pore Ti–Beta, Ti–MWW is less active than in the oxidation of cyclohexene using H 2 O 2 , but its shows comparable activity in the case of TBHP. Ti–MWW is very stable in both the structure and the states of Ti species in the actual cycle of reaction–regeneration. The framework B species remaining within the Ti–MWW catalysts seem to have little influence on the intrinsic activity of framework Ti species, but they act as Bronsted acid sites contributing to the hydrolysis of the oxide product to form glycols. The turnover number (TON) of Ti–MWW for the cyclohexene conversion decreases sharply with increasing Ti content, while the TON for the 1-hexene conversion shows volcanic behavior when related to the Ti content. It is clarified that the bulky reaction is catalyzed mainly by the Ti species within the supercages and the exterior pockets of the MWW structure, while in addition to these highly accessible Ti species, those within the channels of a 10-membered ring greatly contribute to the oxidation reactions not significantly sizedemanding.

Beta zeolite obtained from seeded synthesis without the use of organic structure directing agents (OSDAs) has been used as a catalyst in different types of reactions. The large number of strong acid sites resulted in a high activity for the alkylation of benzene with ethene and a high cracking activity in the hydroconversion of n-decane. However, the high framework polarity resulted in fast deactivation in the acylation of aromatic ethers. Dealumination treatments resulted in improved stability in alkylation reactions with the more reactive olefins like propene. In acylation reactions, the activity was significantly increased, and in hydroconversion, a better balance between the hydrogenation/dehydrogenation and the acid sites was obtained. © 2013 Elsevier Inc. All rights reserved. publisher: Elsevier articletitle: Catalytic applications of OSDA-free Beta zeolite journaltitle: Journal of Catalysis articlelink: http://dx.doi.org/10.1016/j.jcat.2013.05.025 content_type: article copyright: Copyright © 2013 Elsevier Inc. All rights reserved. ispartof: Journal of Catalysis vol:308 pages:73-81 status: published

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Oxygen-permeable membranes of Ba1.0Co0.7Fe0.2Nb0.1O3−δ (BCFN) coated with Ru2.0wt%Rh0.2wt%/Co0.3Mg0.7O catalyst have high oxygen permeability and can be used for the production of synthesis gas fro...

Ordered mesoporous transition metal oxides were successfully crystallized after strengthening the amorphous framework by a silica layer, which efficiently protected the original mesoporous structure against crystallization and resulting mass transfer.