Influence of adhesive on the performance of extruded ZSM-5 catalysts in naphtha cracking

Six adhesives were used to prepare ZSM-5 catalysts through kneading and extruding. The extruded ZSM-5 catalysts were characterized by SEM, NH₃-TPD and N₂ physical sorption and used in naphtha cracking. The results indicated that these ZSM-5 extrudants have no significant differences in their morphology and specific surface area, but have markedly more secondary pores compared with the original ZSM-5 sample. With pure silicon collosol as the adhesive, the resultant ZSM-5 extrudant exhibits lower acid amount, cumulative pore volume, micropore surface area and volume than the original ZSM-5 sample; however, the acid amount, surface area and cumulative pore volume of the extrudants obtained with aluminum-containing adhesives are almost identical to those of the original ZSM-5. For the naphtha cracking in a fixed bed reactor at 600 ℃, the yield of ethylene plus propylene over the extruded ZSM-5 catalyst with silicon collosol as additive is lower than that over the extrudants obtained with aluminum-containing adhesives.