正构烷烃在Pt/SAPO-11催化剂上加氢异构反应性能

Performance of n-alkane isomerization over Pt/SAPO-11 catalyst

采用SAPO-11分子筛制备Pt/SAPO-11双功能加氢异构催化剂,以n-C_8、n-C_(12)和n-C_(16)为模型化合物考察正构烷烃的加氢异构反应性能。结果表明,所制备的催化剂具有较好的异构化活性和选择性,其中单甲基支链异构产物收率和总异构产物收率分别可达60%和75%以上,是低凝柴油和高档润滑油基础油的理想组分。不同链长正构烷烃的异构化产物分布基本一致,但链长较长的正构烷烃更容易发生异构化反应和裂解反应,在保证相同转化率条件下长链烷烃裂解产物收率偏高且异构选择性降低。

A Pt/SAPO-11 dual functional catalyst was prepared from hydrothermally synthesized SAPO-11 molecular sieve and used to study hydroisomerization of n-C8, n-C12 and n-C16 alkanes. Results indicated that this catalyst had good isomerization activity and high selectivity as a result of appropriate acid center and hierarchical pore distribution. Yields for monomethyl-branched isomers and total branched isomers, ideal components for low freezing point diesel and high-grade lubricant, were above 60% and 75% respectively. The distribution of isomerization products was almost the same for n-alkanes of different chain lengths, which monomethyl-branched isomers were about 75% of total isomerization products and 40% were monomethyl-branched isomers with methyl group at middle chain. Isomerization and hydrocracking reactions were more likely to occur on longer chain n-alkanes. Under the same conversion, long-chain n-alkanes showed increase in hydrocracking but decrease in isomerization selectivity.