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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. [ABSTRACT FROM AUTHOR]

Treatment of the zeolitic layered precursor of Al-MWW, so-called Al-MWW(P), with diethoxydimethylsilane (DEDMS) in acidic media leads to the formation of an aluminosilicate-type interlayer-expanded zeolite MWW (Al-IEZ-MWW) with expanded 12-membered ring (12-MR) micropores. However, the silylation process under acidic conditions simultaneously causes dealumination from the MWW framework, resulting in a decrease in the acid amount. We have developed a method for preparing Al-IEZ-MWW without leaching of the Al species. The strategy is to conduct the silylation under weakly acidic conditions; the silylation was conducted in an aqueous solution of an ammonium salt, e.g., NH4Cl, instead of HNO3. Subsequent additional acid treatment led to the formation of Al-IEZ-MWW that shows a high catalytic performance in the acylation of anisole compared to typical Al-MWWas well as Al-IEZ-MWW directly prepared under acidic conditions. The change in the state of Al atoms during the preparation process was investigated by high-resolution solid-state 27Al MAS NMR and 27Al MQMAS NMR techniques. [ABSTRACT FROM AUTHOR]

Vapor-phase silylation of Al-MWW layered precursor with SiMe2Cl2and following calcination produced an interlayer-expanded MWW structure with 12-membered ring micropores without delamination as a result of the formation of silica puncheons between the MWW sheets; strong acidity of zeolitic nature was retained. [ABSTRACT FROM AUTHOR]

Microporous titanosilicate Ti-MCM-68 (Ti-MSE) was successfully synthesized by post-synthetic isomorphous substitution of Ti for Al and proved to be a high-performance catalyst, in particular showing superior performance to TS-1, Ti-BEA, and Ti-MWW for phenol oxidation using H2O2as an oxidant. [ABSTRACT FROM AUTHOR]

The study of methylation of ethene with methanol to propene over MFI zeolites with different heteroatoms has found that an efficient catalyst with weak acidities prevented the side reactions related with the formation of ethene oligomers from occurring, as evidenced by in situ IR spectroscopy, leading to superior propene selectivity in the product distribution. [ABSTRACT FROM AUTHOR]

The all-silica zeolite RUB-41, containing 8- and 10-membered rings, is able to separate trans-2-butene and cis-2-butene from 1-butene and represents a possible improvement in isolating pure 1-butene from a butene mixture. [ABSTRACT FROM AUTHOR]

The interlayer silylation of pure silica PLS-1 with dichlorodimethylsilane gave a novel organic–inorganic hybrid zeolite IEZ-1, of which the micropores are able to adsorb benzene molecules, in contrast to its purely inorganic analogue IEZ-2. [ABSTRACT FROM AUTHOR]