新型介孔Ni/TiO_2-Al_2O_3催化剂的表征及其用于选择加氢反应

采用XRD、SEM、低温N2吸附-脱附、XPS和吡啶吸附FTIR等方法对以TiO2-Al2O3为复合载体、Ni为活性组分的Ni/TiO2-Al2O3加氢催化剂进行了表征,并在裂解汽油一段选择加氢反应中考察了Ni/TiO2-Al2 O3催化剂的活性和稳定性。表征结果显示,TiO2-Al2O3载体中TiO2为锐钛矿相,Al2O3为γ-Al2O3相,焙烧后催化剂中Ni组分以NiO的形态存在;TiO2与活性组分Ni之间存在协同作用而发生了化学位移,该协同作用可促进活性金属组分在载体上的高度分散,增强二烯烃的加氢活性;TiO2-Al2O3复合载体具有适宜的孔分布和较发达的介孔结构,既保留了Al2 O3的骨架优势,又结合了TiO2优良的催化性能;TiO2-Al2O3复合载体表面存在B酸和L酸中心,以弱酸和中强酸为主。工业侧线评价结果表明,加氢产物的双烯值(基于100 g原料油)不大于8.0 g,溴价(基于100 g原料油)小于21 g,催化剂具有较高的加氢活性、选择性和稳定性。

Characterization of a New Mesoporous Ni/TiO_2-Al_2O_3 Catalyst and Its Application in Selective Hydrogenation

Ni/TiO2-Al2O3 catalyst used in the first-stage selective hydrogenation of pyrolysis gasoline was prepared and characterized by means of XRD,SEM,N2 adsorption-desorption,XPS and pyridine adsorbed FTIR.The activity and stability of the catalyst for the hydrogenation was evaluated in an isothermal continuous flow reactor.The results showed that TiO2 and Al2O3 in the support and Ni in the catalyst existed in the forms of anatase,γ-Al2O3 and NiO respectively.Chemical shift between TiO2 and Ni took place because of their synergistic action,which improved dispersity of the active metal component on the support and enhanced the hydrogenation activity for the diolefins.TiO2-Al2O3 composite support had appropriate pore distribution and well-developed mesoporous structure,which kept the skeleton of Al2O3 and developed catalytic performance of TiO2 in the hydrogenation.Both B acid and L acid centers with weak and medium acid strength existed on the support surface.In the pilot-scale evaluation test,the diene value and bromine value(per 100 g feedstock oil)of the hydrogenation products were less than 8.0 g and less than 21 g respectively.All the catalytic activity,selectivity and stability of Ni/TiO2-Al2O3 catalyst for the selective hydrogenation were high.