CuNaX催化乙苯选择氧化制苯乙酮

采用离子交换法制备了一系列不同铜含量的CuNaX催化剂。该催化剂能有效催化以叔丁基过氧化氢(TBHP)为氧化剂的液相乙苯选择氧化反应,产物以苯乙酮为主。在催化剂用量200mg、乙苯用量6mmol、TBHP用量12mmol、乙腈用量1mL、反应温度80℃、反应时间10h的优化反应条件下,乙苯转化率达到78%,苯乙酮选择性为98%,且催化剂能多次循环使用。XRD,DRS,H2-TPR表征结果表明,当铜质量分数小于6.0%时,交换到NaX分子筛中的铜离子主要位于分子筛的超笼中;而当铜质量分数超过6.0%时,交换到NaX分子筛中的铜离子主要位于分子筛的方钠石笼或六角柱笼中。位于NaX分子筛超笼中的六配位的铜离子是催化以TBHP为氧化剂的乙苯选择氧化制苯乙酮反应的活性组分。

Selective Oxidation of Ethylbenzene to Acetophenone over CuNaX Catalysts

A series of CuNaX catalysts with different copper contents were prepared through ion-exchange method and used in selective oxidation of ethylbenzene with tert-butyl hydroperoxide(TBHP) to acetophenone in liquid phase.Under the optimized conditions:CuNaX-6.0 catalyst dosage 200 mg,ethylbenzene dosage 6 mmol,TBHP dosage 12 mmol,acetonitrile volume 1 mL,reaction temperature 80 ℃ and reaction time 10 h,conversion of ethylbenzene and selectivity to acetophenone could reach 78% and 98%,respectively.The catalyst could be recycled for several times without evident loss of the activity.The results of XRD,DRS and H2-TPR suggested that Cu ions were mainly located in the NaX supercages when Cu mass fraction was lower than 6.0%(w).But Cu ions would be exchanged into sodalite cages and/or hexagonal prism cages when the Cu mass fraction was higher than 6.0%(w).The key active component for the selective oxidation was the Cu ions in the supercages of NaX,which mainly existed as six coordination Cu(Ⅱ).