Keggin结构硅钼钒酸铯催化苯直接羟基化

Catalytic Hydroxylation of Benzene to Phenol over Cesium Salt of Keggin-type Molybdovanadosilicic Heteropoly Acid

采用乙醚反萃取方法合成了硅钼钒酸H5SiMo11VO40,与碳酸铯作用得到硅钼钒酸铯CsnH5-nSiMo11VO40（n=1~5）,利用X射线粉末衍射（XRD）、红外（FT-IR）、物理吸附以及扫描电镜（SEM）等对硅钼钒铯进行表征,并以H2O2为氧化剂,评价硅钼钒铯对苯直接羟基化反应的催化性能,系统研究了反应时间、催化剂用量、H2O2用量等反应条件对催化反应的影响。结果表明：合成硅钼钒酸铯具有典型的Keggin结构,且在催化苯直接羟基化反应后,催化剂的Keggin结构也没有被破坏;CsH4SiMo11VO40在催化反应中表现出优良的催化活性,优化条件下,苯直接羟基化为苯酚的收率达到35.9%;硅钼钒酸铯可方便回收,多次重复使用。

Heteropoly acid H5SiMo11VO40 was prepared by ether anti-extraction method and then the cesium salts CsnH5-nSiMo11VO40（n=1—5）were prepared and characterized by FT-IR,XRD and SEM methods.The catalytic activity of these catalysts was evaluated in the hydroxylation of benzene to phenol with H2O2 as oxidant.The effects of various parameters on hydroxylation were also tested,which included reaction time,catalyst amount,reaction temperature and reactants ratio.The prepared cesium salt,CsH4SiMo11VO40 presented best catalytic activity,and the yield of phenol could reach35.9% at optimal reaction conditions.CsH4SiMo11VO40 also has excellent stability in the hydroxylation of benzene,and the Keggin-type structure still retained after reused several times.