用于烷基化C9芳烃分离制备均三甲苯的磷钨酸/高岭土催化剂的研究

用浸渍法制备了磷钨酸／高岭土催化剂，用XRD、NH3-TPD等方法对其进行了表征，并考察其催化C9混合芳烃（C9）烷基化反应的性能。结果表明，磷钨酸和高岭土之间存在三种不同的作用形式，当磷钨酸负载量小于10％时形成饱和的磷钨酸盐；中等负载量（20％～40％）时形成酸性较强的不饱和磷钨酸盐；负载量大于40％时，在不饱和磷钨酸盐表面形成磷钨酸晶体。随着磷钨酸负载量的增加，三甲苯的转化率和均三甲苯与甲乙苯的比值逐渐增大，催化剂的烷基化能力增强，当磷钨酸负载量大于40％后，烷基化能力下降。当催化剂磷钨酸的负载量为40％时，反应60min分离后可得到纯度为99．2％的均三甲苯，均三甲苯收率为87．3％。

STUDY ON KAOLIN SUPPORTED PHOSPHO-TUNGSTIC ACID CATALYST FOR MESITYLENE PREPARATION BY ALKYLATION OF C9 AROMATICS

Kaolin supported phospho-tungstic acid catalyst (HPW/kaolin) was prepared by impregnation method and characterized by XRD and NH3-TPD. The catalytic performance of HPW/ kaolin catalyst for the alkylation of C9 mixed aromatics was investigated. Test results showed that inter-reactions existed between HPW and kaolin: when the HPW loading was less than 10%, saturated phosphotungstate was formed; when the HPW loading was in the range of 20% - 40%, acidic unsaturated phosphotungstate was formed; when the HPW loading was over 40%, HPW crystal was formed on the surface of unsaturated phosphotungstate and covered some of the acid sites. With the increase of HPW-loading, the alkylation function of the catalyst increased, thus, the conversion of trimethylbenzene and the ratio of trimethylbenzene to methyl ethyl benzene increased. However, the alkylation function decreased when HPW loading was more than 40%. When the alkylation of C9 mixed aromatics was conducted over a HPW/kaolin catalyst having a HPW loading of 40% and a reaction time of 60 min, a mesitylene yield of 87. 3% with purity of 99. 2% could be obtained after separation.