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

✍ Scribed by Dingfeng Jin; Zhaoyin Hou; Liwei Zhang; Xiaoming Zheng

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 923 KB
• Volume: 131
• Category: Article
• ISSN: 0920-5861
• DOI: 10.1016/j.cattod.2007.10.049

✦ Synopsis

Selective synthesis of para-para 0 -dimethyldiphenylmethane ( para-para 0 -DMDPM) from the condensation between toluene and formaldehyde was investigated over H-X, H-Y, H-ZSM-5, H-mordenite and MCM-41. Characterizations (NH 3 -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 0 -DMDPM reached 71.1% at 1408C over H-beta zeolite and it could be used in recycle without loss of its structure, activity and stereo-selectivity.