不同烷基链磷酸酯对SAPO-11分子筛物化性质及其催化临氢异构化性能的影响

Impact of Different Alkyl Chain Lengths on Physicochemical Properties and Hydroisomerization of SAPO-11 Molecular Sieves Synthesized With Organic Phosphoric Acid Esters

在SAPO-11分子筛溶胶体系中引入不同烷基链有机磷酸酯,合成系列SAPO-11分子筛,研究不同烷基链对SAPO-11分子筛物化性质及其催化正辛烷临氢异构化性能的影响。结果表明,与常规合成方法相比,加入烷基有机磷酸酯可以缩小SAPO-11分子筛粒径,提高分子筛的比表面积、孔容与酸量。随着有机磷酸酯烷基链长的增加,SAPO-11分子筛的粒径先减小后增大,而比表面积、孔容和酸量先增大后减小。加入十二烷基有机磷酸酯合成的SAPO-11-D分子筛具有最小的粒径、最大的比表面积、孔容和最高的酸量。正辛烷临氢异构化反应结果表明,Pt/H-SAPO-11-D催化剂比Pt/H-SAPO-11-N具有更优的异构化活性、更高的双甲基异构体选择性及更低的裂解产物选择性。

After adding organic phosphoric acid esters of different alkyl chain lengths into the SAPO-11 sol system,the physicochemical properties and octane hydroisomerization of SAPO-11 molecular sieves synthesized were studied.The characterization results showed that adding organic phosphoric acid esters could reduce the particle diameter of SAPO-11 and enhance the specific surface area,pore volume and acid amount,as compared with normal synthesis methods.With the increasing lengths of alkyl chain,the particle diameter of SAPO-11 appeared decreasing first and then increasing,but the specific surface area,pore volume and acid amount of SAPO-11 appeared increasing first and then decreasing.The SAPO-11-D molecular sieves synthesized with dodecyl phosphoric acid esters had the smallest particle diameter,the highest specific surface area,pore volume and the highest amount of acid.The results of n-octane hydroisomerization indicated that the catalyst Pt/H-SAPO-11-D exhibited much better hydroisomerization catalytic activity,higher dimethy-isomers selectivity and lower hydrocraking products selectivity,as compared with catalyst Pt/H-SAPO-11-N.