镍污染方式对催化剂裂化性能的影响

研究了催化裂化催化剂中镍含量及镍污染方式对催化剂活性和选择性的影响机理。结果表明,镍对催化剂性能的影响与污染方式有关,镍的存在使催化剂的活性下降,在镍含量相当的情况下,对催化剂活性的影响程度接近。镍的毒性表现为强烈的催化脱氢作用,它使裂化反应选择性变差,但工业平衡剂中镍对催化剂选择性的影响小于实验室污染剂。工业平衡剂中的镍通过减少催化剂活性中心数量,从而影响催化剂的活性;实验室污染剂上的镍通过在催化剂表面附着、阻塞分子筛孔道,减少反应物分子对活性中心的可接近性,从而影响催化剂的活性和选择性。

EFFECT OF THE WAYS of NICKEL CONTAMINATION ON THE CATALYTIC CRACKING PERFORMANCE OF FCC CATALYST

The effect of nickel contamination including nickel contents and contamination ways, on the activity and selectivity of catalytic cracking catalysts was investigated. Results showed that the ways of nickel deposited on the catalyst played an important role on the catalytic performance, and the cracking activity of catalyst decreased with the increase of nickel content. Due to the strong catalytic dehydrogenation of nickel, negative effect on reaction selectivity was observed, such as the yields of dry gas and coke increased. However, the effect of deposited nickel on selectivity was varied with the ways of nickel deposition, e.g. nickel of industrial equilibrium catalyst had less negative effect than that of lab contaminated catalyst. It was found that the nickel of industrial equilibrium catalyst reduced the catalyst activity by way of decrease the number of Brönsted acid sites, and the nickel of lab contaminated catalyst affected the catalyst activity and selectivity by way of decrease the active site accessibility due to the blocking of catalyst channels and zeolite pores.