Proton Conductivity of Acid-Functionalized Zeolite Beta, MCM-41, and MCM-48: Effect of Acid Strength

2008 ◽  
Vol 20 (16) ◽  
pp. 5122-5124 ◽  
Author(s):  
John C. McKeen ◽  
Yushan S. Yan ◽  
Mark E. Davis
Keyword(s):  
Proton Conductivity ◽  
Acid Strength ◽  
Zeolite Beta ◽  
Mcm 41

The Effect of Type of Acid Sites in Molecular Sieves on Activity and Selectivity in Acylation Reactions

2007 ◽  
Vol 72 (5-6) ◽  
pp. 728-746 ◽  
Author(s):  
Martina Bejblová ◽  
Josef Vlk ◽  
Dana Procházková ◽  
Helena Šiklová ◽  
Jiří Čejka
Keyword(s):  
Molecular Sieves ◽  
Molecular Sieve ◽  
Acid Sites ◽  
Acid Strength ◽  
Zeolite Beta ◽  
Mesoporous Molecular Sieves ◽  
Lewis Acid Sites ◽  
Mcm 41 ◽  
Acylation Reactions

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.

Self-Bonded Zeolite Beta/MCM-41 Composite Spheres

2005 ◽  
Vol 12 (3) ◽  
pp. 193-199 ◽  
Author(s):  
Valeri Naydenov ◽  
Lubomira Tosheva ◽  
Johan Sterte
Keyword(s):  
Zeolite Beta ◽  
Mcm 41

Synthesis, characterization, and catalytic properties of a hydrothermally stable Beta/MCM-41 composite from well-crystallized zeolite Beta

2007 ◽  
Vol 15 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Yuping Li ◽  
Wei Zhang ◽  
Xiaoli Wang ◽  
Ying Zhang ◽  
Tao Dou ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Zeolite Beta ◽  
Mcm 41

Proton Conductivity in Sulfonic Acid-Functionalized Zeolite Beta: Effect of Hydroxyl Group

2008 ◽  
Vol 20 (12) ◽  
pp. 3791-3793 ◽  
Author(s):  
John C. McKeen ◽  
Yushan S. Yan ◽  
Mark E. Davis
Keyword(s):  
Proton Conductivity ◽  
Sulfonic Acid ◽  
Zeolite Beta ◽  
Hydroxyl Group ◽  
Beta Effect

Synthesis and characterization of composite molecular sieves comprising zeolite Beta with MCM-41 structures

2001 ◽  
Vol 11 (7) ◽  
pp. 1886-1890 ◽  
Author(s):  
Wanping Guo ◽  
Chunrong Xiong ◽  
Limin Huang ◽  
Quanzhi Li
Keyword(s):  
Molecular Sieves ◽  
Zeolite Beta ◽  
Synthesis And Characterization ◽  
Mcm 41

Designing of In Situ FTIR Cell and its Application

2014 ◽  
Vol 900 ◽  
pp. 390-393
Author(s):  
Ming Jian Luo ◽  
Bing Hu ◽  
Xin Yue Liu
Keyword(s):  
Acid Sites ◽  
Acid Strength ◽  
Ftir Spectra ◽  
Pyridine Adsorption ◽  
In Situ Ftir ◽  
Acid Amount ◽  
Ftir Study ◽  
Easy Operation ◽  
Mcm 41

An easy-operation in-situ FTIR cell is designed and used for the investigation of dehydroxylation and pyridine adsorption FTIR study. The dehydroxylation FTIR spectra of MCM-41 indicate that the isolated, geminal, and oxygen perturbed silanol vibrated at about 3745, 3735 and 3520 cm-1, respectively. Py-FTIR spectra indicate that MCM-41 has none Lewis and Brönsted acid sites while the acid amount and acid strength of AlMCM-41 increase with the decrease of Si/Al.

scholarly journals Tin-containing silicates: structure–activity relations

2012 ◽  
Vol 468 (2143) ◽  
pp. 2000-2016 ◽  
Author(s):  
Christian M. Osmundsen ◽  
Martin Spangsberg Holm ◽  
Søren Dahl ◽  
Esben Taarning
Keyword(s):  
Lewis Acid ◽  
Active Site ◽  
Low Temperatures ◽  
Acid Strength ◽  
Acid Catalysts ◽  
Lewis Acid Catalysts ◽  
Highly Active ◽  
Structure Activity ◽  
Structure Activity Relations ◽  
Mcm 41

The selective conversion of biomass-derived substrates is one of the major challenges facing the chemical industry. Recently, stannosilicates have been employed as highly active and selective Lewis acid catalysts for a number of industrially relevant reactions. In the present work, four different stannosilicates have been investigated: Sn-BEA, Sn-MFI, Sn-MCM-41 and Sn-SBA-15. When comparing the properties of tin sites in the structures, substantial differences are observed. Sn-beta displays the highest Lewis acid strength, as measured by probe molecule studies using infrared spectroscopy, which gives it a significantly higher activity at low temperatures than the other structures investigated. Furthermore, the increased acid strength translates into large differences in selectivity between the catalysts, thus demonstrating the influence of the structure on the active site, and pointing the way forward for tailoring the active site to the desired reaction.

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

2005 ◽  
Vol 70 (11) ◽  
pp. 1829-1847 ◽  
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.

Cubic and Hexagonal Mesoporous Aluminosilicates Assembled from Secondary Building Units Characteristic of Zeolite Beta

2013 ◽  
Vol 781-784 ◽  
pp. 194-197 ◽  
Author(s):  
Wan Ping Guo ◽  
Juan Liu ◽  
Zhen Zhang ◽  
Lin Yu
Keyword(s):  
Catalytic Activity ◽  
Mesoporous Materials ◽  
Catalytic Cracking ◽  
Zeolite Beta ◽  
Mesoporous Aluminosilicates ◽  
Cumene Cracking ◽  
Secondary Building Units ◽  
Cracking Reaction ◽  
Catalytic Cracking Reaction ◽  
Mcm 41

To improve the structure order and catalytic activity of mesoporous materials, cubic (SBU-MCM-48) and hexagonal (SBU-MCM-41) mesoporous aluminosilicates containing secondary building units characteristic of zeolite Beta have been prepared, and characterized by means of XRD, N2 adsorption, IR spectroscopy, catalytic cracking reaction compared with the corresponding MCM-41. We found that the introduction of secondary building units characteristic of zeolite Beta into the mesopore wall could be an effective route to improve the acidity of mesoporous materials. Moreover, cubic SBU-MCM-48 has been more active than hexagonal SBU-MCM-41 for cumene cracking reaction.

Sign in / Sign up

Export Citation Format

Share Document