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|Title:||Hydrogen Spillover Enhanced Acidity of Aluminium-substituted MCM-41 Platinum Bifunctional Catalysts|
|Authors:||Jaenicke, S. |
|Source:||Jaenicke, S.,Chuah, G.K.,Zhan, P. (1999). Hydrogen Spillover Enhanced Acidity of Aluminium-substituted MCM-41 Platinum Bifunctional Catalysts. Studies in Surface Science and Catalysis 121 : 165-170. ScholarBank@NUS Repository.|
|Abstract:||The mesoporous material, MCM-41, has potential applications as a cracking catalyst for heavy crudes and distillation residues. In order to introduce the necessary acid functionalities, Alframework modified MCM-41 with Si/Al from 2 to 60 has been prepared. The catalysts have been characterized by 27AI MAS-NMR, IR of adsorbed pyridine, and catalytic cracking of cumene. During cumene cracking, a rapid build-up of coke on the catalyst was observed. It was attempted to reduce coke formation and increase the cracking activity by low-level Pt-doping (0.25 -1 \vt% Pt). Contrary to expectation, the Pt-doped catalysts showed lower cracking activity than the undoped catalysts when the reaction was carried out in helium. The IR spectra of adsorbed pyridine show that the Pt deposits form at the same acid sites which otherwise catalyze the cracking reaction. However, in hydrogen atmosphere, an enhanced activity was observed. The products were the same as in helium, except that propane was formed instead of propene. The increased activity is explained by spill-over of hydrogen atoms from the Pt-functionality to the alumino-silicate carrier, where H-atoms can lose an electron and convert to H+ (Brönsted site). The spill-over hydrogen is seen in hydrogen TPD as a desorption peak at the unusually high temperature of 600 °C. Copyright ©7999 by Kodansha Ltd.|
|Source Title:||Studies in Surface Science and Catalysis|
|Appears in Collections:||Staff Publications|
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