Catalytic activity of Pt and tungstophosphoric acid supported on MCM-41 for the reduction of NOx in the presence of water vapor

2000 ◽  
Vol 59 (3-4) ◽  
pp. 313-321 ◽  
Author(s):  
A Jentys ◽  
W Schießer ◽  
H Vinek
Author(s):  
Gonul Gunduz ◽  
Rayna P. Dimitrova ◽  
Selahattin Yilmaz

The paper presents a spectroscopic and catalytic study of encapsulated Keggin type heteropoly acid (12-tungstophosphoric acid, HPW) in the mesopores of MCM-41 molecular sieves. Nitrogen physisorption, FTIR, SEM, XRD and catalytic methods have been used to characterize and compare the properties of the samples. Methanol conversion, ?-pinene isomerization and ethyl acetate oxidation have been applied as model reactions for the evaluation of acid site activity. The combined physicochemical and catalytic investigations clearly show that the introduction of 12-tungstophosphoric acid into MCM-41 causes significant changes in the properties of the sample.


2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.


Author(s):  
Mohsen Nikoorazm ◽  
Maryam Khanmoradi ◽  
Masoumeh Sayadian

Introduction:: MCM-41 was synthesized using the sol-gel method. Then two new transition metal complexes of Nickel (II) and Vanadium (IV), were synthesized by immobilization of adenine (6-aminopurine) into MCM-41 mesoporous. The compounds have been characterized by XRD, TGA, SEM, AAS and FT-IR spectral studies. Using these catalysts provided an efficient and enantioselective procedure for oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using hydrogen peroxide at room temperature. Materials and Methods:: To a solution of sulfide or thiol (1 mmol) and H2O2 (5 mmol), a determined amount of the catalyst was added. The reaction mixture was stirred at room temperature for the specific time under solvent free conditions. The progress of the reaction was monitored by TLC using n-hexane: acetone (8:2). Afterwards, the catalyst was removed from the reaction mixture by centrifugation and, then, washed with dichloromethane in order to give the pure products. Results:: All the products were obtained in excellent yields and short reaction times indicating the high activity of the synthesized catalysts. Besides, the catalysts can be recovered and reused for several runs without significant loss in their catalytic activity. Conclusion:: These catalytic systems furnish the products very quickly with excellent yields and VO-6AP-MCM-41 shows high catalytic activity compared to Ni-6AP-MCM-41.


1996 ◽  
Vol 38 (1-2) ◽  
pp. 33-37 ◽  
Author(s):  
Xiu S. Zhao ◽  
Gao Q. Lu ◽  
Graeme J. Millar ◽  
Xin S. Li

2009 ◽  
Vol 79-82 ◽  
pp. 131-134
Author(s):  
Peng Sun ◽  
Yan Kong ◽  
Jun Du ◽  
Xin Jie Xu ◽  
Jun Wang ◽  
...  

A serious of spherical Co-MCM-41s with different cobalt content was synthesized and characterized by XRD, SEM, N2 isotherms and ICP techniques. The influences of synthesis conditions on the structure were also studied. The use of ascorbic acid as reductant had significant influence on the morphology and the catalytic activity of Co-MCM-41. The prepared samples exhibited higher catalytic activity in the direct hydroxylation of benzene by H2O2 than those with common morphology.


ChemCatChem ◽  
2018 ◽  
Vol 10 (23) ◽  
pp. 5434-5440 ◽  
Author(s):  
Dedong He ◽  
Yaliu Zhang ◽  
Shuang Yang ◽  
Yi Mei ◽  
Yongming Luo
Keyword(s):  

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