Abstract: The Y and ZSM-5 zeolite catalysts were characterized by N₂ physical adsorption-desorption, pyridine adsorption Fourier-transform infrared spectrum (Py-FTIR) and temperature-programmed desorption of ammonia (NH₃-TPD), and the effects of reaction temperature and pressure on catalytic performance in heterogenous oligomerization of ethylene were investigated. The results showed that the catalytic cracking catalyst was rich in mesoporous 3-4 nm and weak Lewis acid sites. At 500-550 ℃ and atmospheric pressure, ethylene was not easy to be converted, C₃-C₄ olefin was mainly produced by oligomerization and cracking, and the selectivity of propylene was higher than that of butylene. When the reaction temperature was higher than 550 ℃, the selectivity of coke was greatly increased by the cyclization dehydrogenation of propylene and butylene. Compared with the normal pressure, the catalytic cracking catalyst with weak Lewis acid sites could effectively catalyze ethylene oligomerization with the conversion higher than 70% at reaction pressure of 0.5-1.0 MPa. Increasing the reaction pressure was beneficial to the hydrogen transfer reaction of propylene and butylene, increasing the selectivity of propane and butane, but decreasing the selectivity of coke.

Key words: ethylene, catalytic cracking catalyst, oligomerization, Lewis acid site, hydrogen transfer reaction