La_2O_3对NiO/HMCM-56催化剂C_9~+重芳烃加氢脱烷基性能的影响

采用等体积浸渍法制备了NiO质量分数6%、La2O3添加量不同的La2O3-NiO/HMCM-56催化剂,考察了La2O3添加量和工艺条件对C9+重芳烃加氢脱烷基反应性能的影响,并采用XRD、H2-TPR、NH3-TPD和BET等技术对催化剂的物化性质进行了研究。实验结果表明,添加La2O3可以提高NiO在催化剂上的分散性,改变催化剂的酸性分布与酸量,改善了催化剂的加氢脱烷基性能;在实验范围内,随La2O3添加量的增加,加氢脱烷基反应的深度增加,C9+重芳烃转化率及苯、甲苯和二甲苯(统称BTX)收率增大,但二甲苯的选择性在La2O3添加量(质量分数)为3%时达到最大。采用La2O3添加量为3%的La2O3-NiO/HMCM-56催化剂,在460℃、3.0MPa、重量空速3.62h-1及V(H2)∶V(C9+)=1600的条件下,C+9重芳烃的转化率、BTX收率及BTX选择性分别为75.23%,63.36%,84.23%。

Effect of La2O3 on Performances of NiO/HMCM-56 Catalyst in Hydrodealkylation of C +9 Heavy Aromatics

Several La2O3-NiO/HMCM-56 catalysts with 6%(mass fraction) NiO as main active component and different La2O3 loadings were prepared by the incipient impregnation method. Effects of La2O3 loading and reaction conditions on the catalyst activity in hydrodealkylation of heavy aromatics were investigated. The catalysts were characterized by means of XRD,H2-TPR,NH3-TPD and BET. The results showed that addition of La2O3 heightened nickel species dispersity,changed acidity distribution and acid amount of the catalysts,and improved activities of the catalysts in heavy aromatics hydrodealkylation. Both conversion of C+9 heavy aromatics and yield of BTX(benzene,toluene and xylene) rose with increase of La2O3 loading. But selectivity to xylene was the maximum when La2O3 loading was 3%. Under the conditions of La2O3-NiO/HMCM-56 with 3% La2O3 as catalyst,460 ℃,3.0 MPa,WHSV of C+9 heavy aromatics 3.62 h-1 and V(H2):V(C+9) 1 600,conversion of C+9 heavy aromatics was 75.23%,yield of BTX 63.36% and selectivity to BTX 84.23%.