微量TiO_2对Ni/SiO_2催化剂催化顺酐加氢制γ-丁内酯的促进作用

Promoting Effect of TiO_2 on Hydrogenation of Maleic Anhydride to γ-Butyrolactone Over Ni/SiO_2 Catalyst

采用等体积浸渍法分别制备了Ni/SiO2和含TiO2的Ni/SiO2催化剂,采用XRD、TPR、XPS、N2吸附-脱附技术对催化剂进行了表征,并将催化剂应用于顺酐液相加氢制γ-丁内酯反应中,考察了Ni含量、TiO2添加量、催化剂还原温度对催化剂活性的影响。结果表明,Ni/SiO2催化剂对顺酐液相加氢制γ-丁内酯反应具有很高的催化活性,γ-丁内酯选择性很高;Ni/SiO2添加微量助剂TiO2,可以提高该反应的γ-丁内酯选择性。推测可能是由于TiO2促进了催化剂的还原,产生更多的活性中心,并且在400℃还原时,Ni和TiO2之间产生了强金属-载体相互作用(SMSI效应),TiO2富集到Ni的表面,将电子转移到Ni上,产生了更多有利于吸附羰基的活性中心,从而提高了γ-丁内酯选择性。

A series of Ni/SiO2 and TiO2 containing Ni/SiO2 catalysts impregnation method, and characterized by means of XRD, TPR, were prepared XPS and N2 by incipient adsorptiondesorption. The catalytic performances of Ni/SiO2 and TiO2 containing Ni/SiO2 for the hydrogenation of maleic anhydride to y-butyrolactone were investigated. The influences of Ni loadings, TiO2 addition and reduction temperature on the catalytic activity of catalysts were investigated. It was shown that Ni/SiO2 catalyst exhibited high catalytic activity and selectivity to ？＇-butyrolactone in hydrogenation of maleic anhydride, and the selectivity to ？＇-butyrolactone could be promoted by the addition of TiO2 at low loading. Addition of TiO2 seemed to facilitate the reduction of catalyst to form more active centers. Moreover, the strong metal-support interaction （SMSI） effect occurred between Ni and TiO2 when catalysts were reduced at 400℃ TiO2 was mainly located on the surface of Ni and the transportation of electron from TiO2 to Ni occurred. The improvement of the selectivity to y-butyrolactone might he attributed to the form of active sites that could adsorb strongly C=O bond.