The influence of water on the catalyst behavior of nanosized HZSM-5 zeolites in the ethylation of coking benzene

Abstract The ethylation of benzene, obtained from coke oven gas, with bio-ethanol over nanosized HZSM-5 zeolite catalyst was investigated in a down-flow fixed-bed reactor. X-ray diffraction, thermogravimetric analysis, ultraviolet raman spectrophotometry, ultraviolet visible spectrophotometry, and N 2 adsorption–desorption isotherms measurements were used to characterize catalyst morphology and coke deposit over the spent catalyst. Thiophene in coking benzene promoted the formation of coke. Water contained in bio-ethanol improved the catalyst selectivity and stability, inhibited coke formation and reduced its carbonization. The water also reduced both activity and desulfurization of the catalyst. The role of water in the reaction is due to its stronger adsorption on the active sites than ethanol and thiophene in the feed.