Selective synthesis of para–para′-dimethyldiphenylmethane over H-beta zeolite

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• 作者：Dingfeng Jin ; Zhaoyin Hou ; Liwei Zhang ; Xiaoming Zheng
• 关键词：H-beta zeolite ; Dimethyldiphenylmethane ; Toluene and formaldehyde
• 刊名：Catalysis Today
• 出版年：2008
• 出版时间：29 February 2008
• 年：2008
• 卷：131
• 期：1-4
• 页码：378-384
• 全文大小：922 K

文摘

Selective synthesis of para–para′-dimethyldiphenylmethane (para–para′-DMDPM) from the condensation between toluene and formaldehyde was investigated over H-X, H-Y, H-ZSM-5, H-mordenite and MCM-41. Characterizations (NH₃-TPD-MS and pore structure) disclosed that the catalytic activity of various zeolites depends mainly on its strong acid site and accessibility of the internal pores. H-beta zeolite, with a unique pore sized in 0.66 nm and higher proportion of stronger acid site, exhibited the highest activity and stereo-selectivity (86.5 % ). Small sized H-beta zeolite was more active due to the enhanced accessibility of its acid site, and this kind of zeolite remained a higher stereo-selectivity (>80 % ) even at higher temperature, longer reaction time and recycle usage. The best yield of para–para′-DMDPM reached 71.1 % at 140°C over H-beta zeolite and it could be used in recycle without loss of its structure, activity and stereo-selectivity.