不同金属改性的ZSM-5分子筛正己烷裂解性能

轻烃催化裂解具有裂解温度低、产物分布可调以及可多产丙烯等优点而备受关注。采用等量浸渍法制备了一系列不同金属改性的ZSM-5分子筛催化剂，在固定床微型反应器中评价了其催化正己烷裂解性能。实验结果表明，4种不同金属（Ni，Fe，Cr，Co）改性的ZSM-5分子筛催化剂上正己烷转化率都显示出下降趋势，但下降幅度不同，而且乙烯、丙烯选择性随不同金属的引入变化规律也不同。其中，Fe和Cr的引入对正己烷转化率的影响较小，而Co的引入导致正己烷转化率的下降幅度更大。就丙烯和乙烯选择性而言，随着金属的引入都有所增加。Co的添加对丙烯选择性提高幅度最大。因此，需要更高丙烯选择性时，可以牺牲正己烷转化率获得更多丙烯。

CRACKING PROPERTIES OF n-HEXANE OVER ZSM-5 MODIFIED WITH DIFFERENT METALS

Light hydrocarbon catalytic cracking has attracted much attention because of its low cracking temperature，adjustable product distribution and high propylene yield.A series of ZSM-5 catalysts modified with different metals were prepared by impregnation, and cracking performances of n-hexane over the modified ZSM-5 catalysts were evaluated in the continuous flow fixed-bed reactor. The results showed that the conversion of n-hexane was decreased by ZSM-5 catalysts modified with Ni，Fe，Cr and Co，respectively. The decreasing extent of the conversion of n-hexane was the largest after Co introduction, but the smaller after Fe and Cr introduction. Propylene and ethylene selectivity was different at the same conversion over ZSM-5 modified with different metals. Compared with other metal，Co introduction improved propylene selectivity in larger extent at low conversion of n-hexane. Therefore，in order to get high propylene selectivity，the conversion of n-hexane could be lowered by adding Co.