Investigation of Different Metal Modified Y Zeolite Towards the Ultra-Deep Removal of Thiophene in Coke Oven Gas

Thiophene in coke oven gas can cause the poisoning of methanation catalyst, and thus the ultra-deep removal of thiophene is necessary for the conversion of coke oven gas to methane. NaY zeolite was reported to have this potential, and metal modification over NaY plays an important role on its desulfurization performance. In this paper, series of NaY and metal modified MY zeolite (M=Ce, Ni, Ag and Zn) were prepared, and their desulfurization performances in simulated coke oven gas were investigated. In order to reveal the effect of valence state of Ce species on thiophene adsorption performance, CeY was evaluated in H2/CO-containing atmospheres and N2 atmosphere, and its desulfurization activity was compared after treated under reductive atmospheres at 200 or 600 °C. The results show that AgY sorbent has the highest breakthrough adsorption capacity for thiophene (144 mg/g) at 100 °C, and CeY has the best desulfurization performance at 200 °C compared with other sorbents. Thiophene could be adsorbed via π-complexation over NiY, AgY and ZnY sorbents, however mainly through S-M interaction over CeY sorbent. S-M interaction has higher thermal stability than π-complexation, resulting the relatively low variation in thiophene adsorption over CeY ranges from 100 to 200 °C. Moreover, Ce(IV) species is more favorable for thiophene adsorption than Ce(III) at 200 °C in coke oven gas. Although H2 and CO in coke oven gas would reduce the adsorption capacity of CeY for thiophene, CeY with thiophene adsorption capacity of 31.7 mg/g at 200 °C still has potential industrial utilization for ultra-deep removal of thiophene.