Catalytic Activity of Heteropolytungstic Acid Encapsulated into Mesoporous Material Structure

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Gonul Gunduz ◽  
Rayna P. Dimitrova ◽  
Selahattin Yilmaz
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Mesoporous Material ◽  
Heteropoly Acid ◽  
Methanol Conversion ◽  
Tungstophosphoric Acid ◽  
Material Structure ◽  
Acetate Oxidation ◽  
Mcm 41 ◽  
Model Reactions

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.

Catalytic Activity of Dehydrogenation of Methanol to MF over Cu/MCM-41 and Cu-ZnO/MCM-41 Prepared by Impregnation and Grinding

2011 ◽  
Vol 396-398 ◽  
pp. 730-733
Author(s):  
Guo Ru Li ◽  
Gong Li ◽  
Shu Xi Zhou ◽  
Hui Juan Tong
Keyword(s):  
Catalytic Activity ◽  
Atmospheric Pressure ◽  
Molecular Sieves ◽  
Conversion Rate ◽  
Methyl Formate ◽  
Methanol Conversion ◽  
N2 Adsorption ◽  
Flow Microreactor ◽  
Adsorption Desorption ◽  
Mcm 41

Abstract. Using MCM-41 molecular sieves as the support, Cu-ZnO/MCM-41 and Cu/MCM-41 catalysts were prepared by impregnation and grinding. The catalysts were characterized by XRD, N2 adsorption-desorption and TPR methods. The catalytic activity of the dehydrogenation of methanol to methyl formate (MF) was evaluated using the flow microreactor under atmospheric pressure. According to the results, the catalyst prepared by impregnation had a better selectivity for the MF, but a lower methanol conversion rate. However, the product's selectivity could be improved by adding ZnO additive while the methanol conversion rate was reduced. For Cu/MCM-41 prepared by impregnation and grinding, the methanol conversion rate was 20.18% and 24.13% respectively at 250°C and the MF selectivity was 73.75% and 67.35% respectively. Likewise for Cu-ZnO/MCM-41 prepared by impregnation and grinding, the methanol conversion rate was 15.28% and 18.83% respectively at 250°C and the MF selectivity was 81.31% and 75.32% respectively.

Synthesis, characterization and catalytic activity of actinide Th-MCM-41 and U-MCM-41 hexagonal packed mesoporous molecular sieves

2001 ◽  
Vol 171 (1-2) ◽  
pp. 229-241 ◽  
Author(s):  
Rodica Tismaneanu ◽  
Biswajit Ray ◽  
Rafael Khalfin ◽  
Rafi Semiat ◽  
Moris S. Eisen
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Mesoporous Molecular Sieves ◽  
Mcm 41

Emission Control Catalyst Derived from Mesoporous Molecular Sieves

1996 ◽  
Vol 431 ◽  
Author(s):  
Partha P. Paul ◽  
Michael A. Miller ◽  
Martin J. Heimrich ◽  
Stuart T. Schwab
Keyword(s):  
Catalytic Activity ◽  
Fuel Economy ◽  
Molecular Sieves ◽  
Emission Control ◽  
Mesoporous Molecular Sieves ◽  
Exhaust Gas ◽  
Engine Exhaust ◽  
Combustion Processes ◽  
Mcm 41

AbstractA lean NOx catalyst is needed to control NOx emissions generated by oxygen-rich combustion processes to obtain higher fuel economy. We have developed such a catalyst using modified mesoporous molecular sieves (MCM-41). An iron(II)-complex impregnated MCM-41 has been synthesized which has been further treated with [Pd(NH3)4]Cl2. This treatment resulted in further exchange of Na+ ions of the molecular sieves with Pd(NH3)42+ thus forming Catalyst A. The catalytic activity towards NOx, CO and HC was studied using simulated exhaust gas, as well as engine exhaust gas.

Synthesis of Al-Containing Mesoporous Molecular Sieves and their Catalytic Performance to Isomerization Reaction of Endo-Tetrahydrodicyclo-Pentadiene

2011 ◽  
Vol 233-235 ◽  
pp. 234-237 ◽  
Author(s):  
Sa Liu ◽  
Jian Wei Guo ◽  
Chu Fen Yang ◽  
Long Huan Li ◽  
Yi Hua Cui
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Catalytic Performance ◽  
Mesoporous Molecular Sieves ◽  
Isomerization Reaction ◽  
Inorganic Acid ◽  
Ft Ir ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Mcm 41

Al-containing mesoporous molecular sieves(Al-MCM-41) were synthesized at ambient temperature. The structures of samples were characterized by XRD, N2-adsorption/desorption isotherms and FT-IR, etc. The evaluation results showed that Al-MCM-41 had higher catalytic activity for isomerization conversion of endo-tetrahydrodicyclo-pentadiene (endo-TCD) into exo-tetrahydrodicyclo-pentadiene (exo-TCD) and adamantane (AdH). Loading inorganic acid on the surface of Al-MCM-41 led increase of its catalytic activity and the yield of adamantane.

Immobilization of the heteropoly acid (HPA) H4SiW12O40 (SiW12) on mesoporous molecular sieves (HMS and MCM-41) and their catalytic behavior

1996 ◽  
Vol 42 (3-4) ◽  
pp. 201-208 ◽  
Author(s):  
Wenling Chu ◽  
Xiangguang Yang ◽  
Yongkui Shan ◽  
Xingkai Ye ◽  
Yue Wu
Keyword(s):  
Molecular Sieves ◽  
Heteropoly Acid ◽  
Mesoporous Molecular Sieves ◽  
Catalytic Behavior ◽  
Mcm 41

Synthesis, Characterization and Modification of Mcm-41 Molecular Sieves

1994 ◽  
Vol 371 ◽  
Author(s):  
A. Sayari ◽  
V.R. Karra ◽  
J.S. Reddy ◽  
I.L. Moudrakovski
Keyword(s):  
Catalytic Activity ◽  
Solid State ◽  
Molecular Sieves ◽  
Solid State Nmr ◽  
Hexagonal Phase ◽  
Mesoporous Molecular Sieves ◽  
Ammonium Bromide ◽  
Final Phase ◽  
Dimethyl Ammonium ◽  
Mcm 41

AbstractA series of crystalline mesoporous molecular sieves were prepared using alkyl hexadecyl dimethyl ammonium bromide salts (C16H33)(CnH2n + 1)(CH3)2NBr, in which the number of carbon atoms (n) in one alkyl group was varied from 1 to 12. The influence of (n) value on the nature of the final phase obtained and on its pore size was investigated. A hexagonal phase was obtained for n = 1, 3, 5 and 7, while a lamellar phase was obtained for all other templates. Vanadium and titanium modified MCM-41 molecular sieves were also prepared in the presence of C12H25(CH3)3N+ and C16H33(CH3)3N+ ions, respectively. These materials were characterized by XRD, nitrogen physisorption, FTIR, solid state NMR, XPS, UV-Vis and catalytic testing in the oxidation of 1-naphthol, 2,6-di-tert-butylphenol, norbornylene, n-hexane and propylamine. Ti-MCM-41 exhibited considerable catalytic activity only in the oxidation of aromatics, olefins and alcohols. V-MCM-41 was found to be a good catalyst in the oxidation of aromatics and alkanes.

Thorough investigation of varying template combinations on SAPO-34 synthesis, catalytic activity and stability in the methanol conversion to light olefin

RSC Advances ◽  
2014 ◽  
Vol 4 (91) ◽  
pp. 49762-49769 ◽  
Author(s):  
Mehdi Sedighi ◽  
Hussein Bahrami ◽  
Jafar Towfighi Darian
Keyword(s):  
Catalytic Activity ◽  
Molecular Sieves ◽  
Methanol Conversion ◽  
Hydrothermal Conditions ◽  
Light Olefin ◽  
Tetraethylammonium Hydroxide ◽  
Structure Directing Agents

Crystals of SAPO-34 molecular sieves were synthesized under hydrothermal conditions by using tetraethylammonium hydroxide, morpholine and a mixture of them as structure-directing agents.

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