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Highly selective synthesis of 2,6-bis(4-methylphenyl)pyridine over novel mesoporous solid acid catalysts

✍ Scribed by M. Selvaraj; T.G. Lee


Publisher
Elsevier Science
Year
2005
Tongue
English
Weight
150 KB
Volume
85
Category
Article
ISSN
1387-1811

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✦ Synopsis


Aminocyclization reaction of 4-methyl acetophenone (4-MAP) with formaldehyde and ammonia was contacted under vapor phase reaction conditions over novel mesoporous Zn-Al-MCM-41 catalysts with different Si/(Zn + Al) ratios for highly selective synthesis of 2,6-BP (2,6-bis(4-methylphenyl)pyridine). For the reactions, the influences of various reaction parameters such as different catalysts, reaction temperature, reactant molar ratio, WHSV, TOS and recyclability are discussed. With increasing the Si/ (Zn + Al) ratios of Zn-Al-MCM-41 catalysts from 75 to 380, the conversion of 4-methyl acetophenone (4-MAP), and the yield and selectivity of 2,6-BP decreased because the number of BrΓΈnsted acid sites in Zn-Al-MCM-41 catalysts is found to decrease almost linearly with increasing ratios of Si/(Zn + Al). Further the catalytic results were compared with those obtained by using Al-MCM-41, HY, Hb, HM and H-ZSM-5 zeolites. The conversion and selectivity is increased in Zn-Al-MCM-41( 21) with each cycling of reaction because its catalytic activity does not change. The Si/(Zn + Al) ratio of 21 is found to be more suitable for the aminocyclization reaction of 4-MAP to highly selective synthesis of 2,6-BP. Thus the selectivity of 2,6-BP


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