Effect of the activation temperature on the catalytic activity of clinoptilolite for the benzoylation of biphenyl

Abstract

The Friedel–Crafts benzoylation of biphenyl (BP) was carried out under liquid-phase batch conditions using raw and modified clinoptilolite zeolites as catalysts. Solventless benzoylation of BP with benzoyl chloride preferentially gave p-monoacylated product, 4-phenyl-benzophenone (4-PBP), as the main product for all catalysts used and only small amount of diacylated product, 4,4′-dibenzoylbiphenyl (4,4′-DBBP) was observed. The highest yield of 4-PBP was achieved by using HT-823 zeolite as catalyst. Calcined zeolites, except the clinoptilolite calcined at 1,023 K, are more active than their raw counterparts. Raw clinoptilolite gave 4-PBP yield of 48.5% while the HT-823 proves to be a highly efficient catalyst giving a very high selectivity to 4-PBP (~98.5%) with the conversion of BP ~86.9% at 453 K. The results revealed that zeolite HT-823 is the best catalyst for the benzoylation of biphenyl to 4-PBP. Also, increasing the reaction temperature appeared to play a significant role on the 4-PBP yield.