Shape selective alkylation of biphenyl with propene on SAPO-11 catalysts

Alkylation of biphenyl with propene to produce 4,4'-diisopropylbiphenyl (4,4'-DIPB) was investigated using SAPO-11 catalysts. The catalytic activity of SAPO-11 for the alkylation was low compared with that of H-mordenite (HM), mainly due to its less acidic nature. SAPO-11 exhibited a comparable selectivity for 4,4'-DIPB production to HM, although the pores of SAPO-11 were smaller than those of HM. The 4,4'-DIPB selectivity of SAPO-11 was strongly affected by non-shape selective alkylation on the external acid sites. To eliminate the contribution of external acid sites, the external surface of SAPO-11 was covered with an AIPO(4)-11 shell. This catalyst was less active for this reaction, but exhibited a higher 4,4'-DIPB selectivity than the parent catalyst. These results indicate that the 4,4'-DIPB selectivity was enhanced by inactivating the external acid sites.