タイトル: Vapor-Phase Ethylation of Biphenyl over MTW Zeolites
著者: Mulla, Shafeek Abdul Rashid; Waghmode, Suresh B.; Watanabe, Seiji; Maekawa, Hiroyoshi; Komura, Kenichi; Kubota, Yoshihiro; Sugi, Yoshihiro; Kim, Jong-Ho; Seo, Gon
抄録: Vapor-phase ethylation of biphenyl (BP) with ethanol over the MTW zeolites was examined by using a fixed-bedflow reactor, and compared to the catalyses over MOR and MFI zeolites. Two types of MTW zeolites: MTW-S (smallcrystal) and MTW-L (large crystal) were synthesized under hydrothermal conditions. The selectivity for 4,40-diethylbiphenyl(4,40-DEBP) over the MTW zeolites was the highest among the other zeolites, such as MOR and MFI. Thecatalytic activity of MTW-S was higher than MTW-L. The selectivities for 4,40-DEBP at 300 C were ca. 30% forMTW-S and ca. 22% for MTW-L among the DEBP isomers. The dealumination of the MTW zeolites enhanced the selectivityfor 4,40-DEBP although the catalytic activity was slightly decreased. In particular, the selectivity for 4,40-DEBPover dealuminated MTW-L by steaming and subsequent refluxing in hydrochloric acid increased from 22 to 42% at300 C. The enhancement of the selectivity for 4,40-DEBP is due to the decrease in non-selective reactions at externalacid sites because these sites are removed by the dealumination. The selectivities are higher than those of equilibriummixtures, and the slimmest isomer. 4,40-DEBP is preferentially formed due to the steric interaction of reactants and productswith acidic sites in the MTW channels. Molecular modeling on the diffusion of products in the MTW channel suggeststhat 4,40-DEBP isomer can diffuse most easily among DEBP isomers. 4,40-DEBP and other isomers easily diffuseinside MOR channel; however, they cannot in the MFI channels. These results show that the formation of 4,40-DEBP isthe most favorable due to the diffusion and the restriction of transition state in the MTW channels.
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