铅钛复合氧化物催化剂上CO水合制低碳醇

Conversion of CO and Water to Alcohols on PbTiO_3 Composite Oxide Catalyst

用溶胶 凝胶法制备了不同Pb/Ti摩尔比的铅钛复合氧化物催化剂 ,并用XRD ,TPR和XPS等技术对样品进行了表征 .结果表明 ,铅钛复合氧化物的比表面积随着样品中Pb含量的增加而减小 .氧化钛的添加对氧化铅的还原行为有较大影响 ,随着复合氧化物中铅含量的增加 ,氧化铅的中温 (～ 5 85℃ )还原峰面积增大 ,而低温 (～ 4 5 0℃ )和高温 (～ 6 4 0℃ )还原峰面积减小 .铅钛复合氧化物应用于CO水合制低碳醇反应的结果表明 ,氧化钛的添加不但使醇产物中乙醇的选择性升高 ,副产物CO2 的选择性下降 ,而且使催化剂的稳定性有较大改善 .催化剂的活性中心被部分覆盖和PbTiO3 催化剂中的Pb(Ⅱ )被部分还原为金属Pb都导致催化剂的失活 .将失活催化剂在空气中焙烧然后水洗 。

The PbTiO 3 composite oxide catalyst samples with different Pb/Ti molar ratios were prepared by the sol-gel method and characterized by XRD, TPR and XPS. The specific surface area of the catalyst decreases with increasing PbO content in the catalyst. The reduction behavior of PbO is apparently affected by the addition of TiO 2. Increasing the TiO 2 amount, the area of the middle temperature (～585 ℃) reduction peak of PbO decreases, while the area of the low temperature (～450 ℃) and high temperature (～640 ℃) reduction peaks increases. When used as a catalyst for the conversion of CO and water to alcohols, the PbTiO 3 composite oxide shows better stability than pure PbO, although the stability of the samples with different Pb/Ti molar ratios is similar. Upon the addition of TiO 2 to PbO, the ethanol selectivity increases and the CO 2 selectivity decreases. The partial coverage of catalyst active centers and the reduction of Pb(Ⅱ) to Pb(0) result in the deactivation of the PbTiO 3 catalyst. Treatment of the deactivated catalyst by air combustion and then water wash or water wash and then air combustion can recover the original activity of the fresh one.