Hierarchical composite catalysts of MCM-41 on zeolite Beta for conversion of heavy reformate to xylenes

The role of the type of acid site (Broensted vs. Lewis) on the activity and selectivity of molecular sieve catalysts was investigated in ferrocene and toluene acylation. H-, Zn-, Fe-, Al- and La-forms of zeolite Beta, USY and mesoporous molecular sieves (Al)MCM-41, (Al)SBA-15 were tested. It was observed that addition of metal cations acting as Lewis acid sites can increase the acidity of various molecular sieve catalysts. No general relationship between the type of cation and conversion of individual substrate was found. While the highest activity in ferrocene acylation was observed after addition of Zn, in the case of toluene acylation Al-forms of catalysts were the most active. The results indicate that the acid strength of cationic Lewis sites controls their activity in acylation reactions.

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Synthesis and characterization of Cu–BiVO4/MCM-41 composite catalysts with enhanced visible light photocatalytic activities

Journal of Materials Science Materials in Electronics ◽

10.1007/s10854-016-4883-9 ◽

2016 ◽

Vol 27 (8) ◽

pp. 8633-8640 ◽

Cited By ~ 3

Author(s):

Yulin Xing ◽

Junxia Wang ◽

Long Chen ◽

Anqi Wang ◽

Fan Li ◽

...

Keyword(s):

Visible Light ◽

Synthesis And Characterization ◽

Composite Catalysts ◽

Photocatalytic Activities ◽

Visible Light Photocatalytic ◽

Mcm 41

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Micro/Mesoporous Composites Based on Colloidal Zeolite Grown in Mesoporous Matrix

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20051829 ◽

2005 ◽

Vol 70 (11) ◽

pp. 1829-1847 ◽

Cited By ~ 6

Author(s):

Pavla Prokešová ◽

Nikolay Petkov ◽

Jiří Čejka ◽

Svetlana Mintova ◽

Thomas Bein

Keyword(s):

Composite Materials ◽

Acid Sites ◽

Zeolite Beta ◽

Silica Matrix ◽

Beta Zeolite ◽

Colloidal Solutions ◽

Mesoporous Composites ◽

Hexagonally Ordered ◽

Mcm 41 ◽

Mesostructured Material

Composite materials containing micro- and mesopores are prepared under instantaneous hydrothermal treatment of initial solutions generally used for zeolite Beta and precursor solutions for mesoporous Al-MCM-41 material. The resulting composites are compared with pure, highly crystalline colloidal microporous Beta zeolite and hexagonally ordered mesostructured samples. The porosity and morphological features of the composite materials are influenced by the conditions of hydrothermal synthesis of the initial colloidal solutions used for the preparation of Beta seeds, as well as by the conditions of the synchronized crystallization of the final composites. The embedding of Beta seeds in the mesoporous silica matrix is possible via immediate heating of mesoporous precursor solutions with Beta seeds primarily formed. The composite materials contain either microcrystalline Beta nanodomains with sizes of about 5-10 nm surrounded by mesoporous material or defined Beta nanocrystals (20-40 nm), and at the same time connected with mesostructured material. The presence of highly crosslinked silicate framework walls and tetrahedrally coordinated aluminum in the composite material are confirmed by solid-state 29Si and 27Al MAS NMR spectroscopy. The concentration of Brønsted acid sites in the micro/mesoporous composites is increased substantially in comparison with pure mesoporous Al-MCM-41 material proven by FTIR acetonitrile-d3 adsorption study.

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