Role of acid and base sites in the side-chain alkylation of alkylbenzenes with methanol on two-ion-exchanged zeolites

The role of acid and base sites in the side-chain alkylation has been investigated using p-xylene as alkylbenzene on single- and two-ion-exchanged zeolites. Rb and Li two-ion-exchanged X type zeolites with the LiRb + Li ratio of about 0.1 showed a higher activity than RbX and KX which showed the highest activity in single-ion-exchanged zeolites. RbX with a small amount of Li ion has slightly stronger acid sites than RbX, as measured by the temperature-programmed desorption (TPD) of ammonia and the Hammett indicators. Two cations in a zeolite are considered to form different active sites, such as acid and base sites, under their mutual effect. It is concluded that the active center which is the assemblage of acid and base sites with cooperative action is necessary in the side-chain alkylation of alkylbenzenes with methanol.