The Desorption Law and Alkylation of Benzene With Methanol on HZSM-5 Zeolites

Temperature-programmed surface reaction mass spectrometry (TPSR-MS) experiments were conducted on HZSM-5 zeolites of different n(SiO2)/n(Al2O3), and temperature-programmed desorption (TPD) method was used to investigate the adsorption-desorption performances of benzene or methanol on the zeolites. The results showed that with increased n(SiO2)/n(Al2O3) of HZSM-5 zeolites, the acid strength and acid quantity declined. Ethylene was detected during TPD after benzene adsorpted on HZSM-5 at 60℃, and the higher silica to alumina ratio, the less ethylene was detected and the more desorption of benzene occurred. Toluene was found during TPD after methanol adsorbed on HZSM-5 at 60℃, but benzene was not detected; with the higher silica to alumina ratio, the less amount of toluene was detected and the more desorption of methanol occurred. The above results showed that the high n(SiO2)/n(Al2O3) of HZSM-5 is beneficial for benzene or methanol to exist in the form of a single molecule. The alkylation results showed the HZSM-5 of high n(SiO2)/n(Al2O3) were favorable to reaction of benzene and methanol, but HZSM-5 of low n(SiO2)/n(Al2O3) were easily deactivated; clearly, the acidity plays an important role in alkylation of benzene and methanol. © 2017, Editorial Office of Acta Petrolei Sinica(Petroleum Processing Section). All right reserved.