SO_4^(2-)/ZrO_2固体超强酸催化剂上异丁烷与丁烯烷基化的研究

Isobutane Alkylation with Butene on SO_4^(2-)/ZrO_2 Superacid Catalysts

在固定床连续性微反活性评价装置上 ,考察了异丁烷与丁烯在SO4 2 - /ZrO2 系列固体超强酸催化剂上烷基化反应的活性和选择性 ,借助XRD、DTA、NH3-TPD等分析方法对SO4 2 - /ZrO2 催化剂的结构和性能进行了表征。结果表明 ,SO4 2 - /ZrO2 催化剂表面酸性位的强度与焙烧温度密切相关。同时 ,SO4 2 - /ZrO2 固体超强酸催化剂上的中强酸位是烷基化反应的主要活性位 ,但酸强度越高 ,其比活性越高 ,而目标产物三甲基戊烷选择性越低。SO4 2 - /ZrO2 催化剂的弱酸位有利于烯烃齐聚反应 ,强酸位有利于裂化反应 ,氢转移、异构化反应一般发生在中强酸位 ,与烷基化反应要求的酸性位很接近 ,烷基化反应酸强度控制在 -8 1～ -12

The activity and selectivity of SO 2- 4/ZrO 2 solid superacid catalysts for the alkylation of isobutane with butene were extensively investigated in a continuous fixed-bed microreactor.The crystal structure,thermal stability and acidity of the catalysts were characterized by means of XRD,DTA and NH 3-TPD methods.The results indicated that strength of acid sites on SO 2- 4/ZrO 2 catalysts was closely correlated with calcination temperature.The medium strong acid sites were the main active sites of alkylation reaction.The higher the acid strength of the catalyst is,the higher the relative activity,and the lower the selectivity of the target products.In general,weak and strong acid sites of the catalysts favor oligomerization and catalytic cracking,respectively. Hydrogen fransfer and isomerization take place easily on medium strong acid sites.The optimum range of acid strength of SO 2- 4/ZrO 2 catalysts for alkylation of isobutane with butenes is -12.7～-8.1.