MCM-49分子筛催化剂上1-丁烯的骨架异构化反应

 采用动态和静态水热合成法合成了不同Si/Al比的MCM-49分子筛,并考察了合成分子筛对1-丁烯骨架异构化反应的催化性能. 结果表明,除目的产物异丁烯外,主要副产物为丙烯和戊烯,产物中没有检测到C6以上的副产物. 异丁烯收率随着反应温度的升高、分子筛晶粒的增大和1-丁烯分压的降低而升高. NH3-TPD 结果表明,随着分子筛Si/Al比的增加,分子筛的酸中心数减少,导致副产物选择性下降,异丁烯选择性升高. 根据反应结果讨论了异丁烯及副产物形成的机理.

Isomerization of 1-Butene on MCM-49 Molecular Sieve Catalyst

MCM-49 molecular sieve with different Si/Al ratios was synthesized hydrothermally under static condition and dynamic condition (autoclave rotated at 60 r/min), and its catalytic performance for skeletal isomerization of 1-butene was studied. The reaction results indicated that, besides the aim product isobutene, propylene and pentenes formed by dimerization-cracking reaction or oligomerization-cracking reaction were the main by-products, and the hydrocarbons higher than C 6 were not detected. Moreover, the yield of isobutene increased with the increase of reaction temperature and molecular sieve crystallite as well as the decrease of 1-butene partial pressure. The NH 3-TPD result indicated that the amount of acid sites decreased with the increase of Si/Al ratio in molecular sieve, which resulted in slower secondary reaction rate and higher selectivity for isobutene. On the basis of these results, the formation mechanism of isobutene and other by-products on MCM-49 was discussed.