β沸石上环己烯与乙酸的加成反应

ADDITION REACTION OF CYCLOHEXENE AND ACETIC ACID OVER β ZEOLITE

ＴＰＤ研究表明，焙烧温度为５００℃时，Ｈβ沸石表面酸量最大，高于或低于这个温度，表面酸量都下降，而酸的强度始终随焙烧温度的升高而增强．在环己烯与乙酸的加成反应中，该沸石催化剂活性与酸量的变化规律相一致，但选择性随酸强度的增加而下降．用ＧＣ－ＩＲ对反应的副产物进行了研究，探讨了催化剂失活的机理，证明了２－环己烯酮、２－环己烯基环己酮等羰基化合物是催化剂致毒物．同时考察了反应时间、温度及酸／烯摩尔比对反应的影响．结果表明，酸／烯摩尔比为５．５：１．在１００℃和自生压力下反应４ｈ，环己烯的转化率可达８４％左右，乙酸环己酯的选择性可达９０％以上．

he addition reaction of acetic acid to cyclohexene over β zeolite was studied. NH3-TPD profiles show that when NH4β was calcined at 500℃, the surface acid amount of zeolite has a maximum value; when NH4β was calcined at >500℃ or <500℃, the surface acid amounts of zeolite were all decreased, but the surface acid strength was throughout risen with the increase of the calcination temperature. The catalytic activity for the addition reaction of cyclohexene-acetic acid was increased with the surface acid amount, but the selectivity was decreased with the increase of the acid strength. By-products in the reaction were studied by GC-IR method. The mechanism of deactivation of catalyst was discussed. It was found that some carbonyl compounds, such as 2-cyclohexene-[1]-one, cyclohexanone and 2-cyclohexylcyclohexanone etc.could deactivate the catalyst. The effects of the reaction conditions were investigated, the results showed that under the condition of acetic aicd/cyclohexene molar ratio 5. 5: 1, reaction temperature 110℃, reaction time 4 h and self-sustaining pressure, the conversion of cyclohexene attained 84% and the selectivity for cyclohexyl acetate exceeded 90%.