Dawson结构磷钼钒酸铯催化H2O2氧化苯合成苯酚

摘要

Heteropoly acid H8 P2 Mo16 V2 O62 with Dawson structure was prepared by ether anti-extraction method and then the cesium salts CsnH8-nP2Mo16V2O62(n=1-5)were prepared. These cesium salts ware characterized by IR,XRD and SEM methods. The cata-lytic activity of these catalysts was evaluated in the hydroxylation of benzene to phenol with H2 O2 as oxidant. The effects of various parameters on hydroxylation were also tested,which included reaction time,catalyst amount,reaction temperature,different solvents and reactants ratio. Results indicated that the prepared cesium salt, Cs3 H5 P2 Mo16 V2 O62 presented best catalytic activity, and the yield of phenol could reach 31. 0%at optimal reaction conditions. Cs3 H5 P2 Mo16 V2 O62 also had excellent stability in the hydroxyl-ation of benzene,and the Dawson-type structure still retained after reused several times.%采用乙醚反萃取方法合成了Dawson结构磷钼钒酸H8 P2 Mo16 V2 O62,进而与碳酸铯反应得到Dawson结构磷钼钒酸铯催化剂CsnH8-nP2Mo16V2O62(n=1-5),利用X射线粉末衍射(XRD)、红外(FTIR)以及SEM等对催化剂进行分析,并以H2 O2为氧化剂,评价其在苯液相氧化直接羟基化合成苯酚反应中的催化性能,系统的研究了反应时间、催化剂用量、H2 O2用量、反应溶剂等反应条件对催化反应的影响。结果表明,合成Cs3 H5 P2 Mo16 V2 O62在催化反应中表现出优良的催化活性,优化条件下,苯酚收率达到31．0%；催化剂回收方便,可多次重复使用,在反应过程中,催化剂的Dawson结构没有明显变化。