Effect of zinc salt on the synthesis of ZSM-5 for alkylation of benzene with ethanol

ZSM-5 zeolites were synthesized by adding Zn(NO3)2 aqueous solution into the gel precursor. The materials were characterized by XRD, ICP, nitrogen adsorption, FT–IR, SEM, 27Al MAS NMR, NH3–TPD and Py–IR. After adding zinc salt into the gel precursor at synthesis, the products crystal size decreased obviously and the ratio of Lewis/Brönsted acid increased significantly. All the ZSM-5 samples synthesized in presence of zinc salt contained a small amount of zinc, the maximum was 0.026 wt%. Catalytic tests of alkylation of benzene with ethanol were investigated over these materials and the zinc containing catalysts showed higher ethylbenzene selectivity. The increased ethylbenzene selectivity was attributed to the change of acidity and crystal size.