Nature of shape-selective catalysis in the ethylation and the isopropylation of biphenyl over H-mordenites

摘要

The isopropylation of 3- and 4-isopropylbiphenyls (3- and 4-IPBP) and the ethylation of 3-and 4-ethylbiphenyls (3- and 4-EBP) were examined over HM to know the mechanism ofshape-selective alkylation of BP over HM. 4-IPBP was consumed rapidly compared with 3-IPBP in the isopropylation of the mixtures of 3- and 4-IPBP under propylene pressure. Theselectivity for 4,4’-diisopropylbiphenyl (4,4’-DIPB) in bulk products was decreased with theincrease of 3-IPBP; however, the selectivity for 4,4’-DIPB in encapsulated products keptconstant in every ratio. The shape-selective formation of 4,4’-DIPB occurs inside the pores,and some of 3-IPBP probably participates in the formation of 3,4’-DIPB on the external acidsites. 4-EBP also disappeared faster than 3-EBP in the ethylation of mixtures of 3- and 4-EBPunder ethylene pressure. The selectivity for 4,4’-DEBP was less than 2 % in both bulk andencapsulated products, whereas total selectivity for DEBPs with 4-ethyl group was higher than65 % in both products: DEBP isomers were predominantly produced from 4-EBP. HM poreswere too loose to form the least bulky 4,4’-DEBP by shape-selective catalysis: 4,4’-DEBPdisappeared rapidly among DEBPs to form polyalkylbiphenyls (PEBP).