La、EDTA改性对Ni-W/TiO2-Al2O3催化剂结构及加氢脱硫性能的影响

摘要

Using nickel-tungsten as active metals and TiO2 -Al2 O3 as the support,Ni-W/TiO2 -Al2 O3 catalysts for the hydrodesulfurization of heavy oil were prepared by wetness impregnation. The effects of the modification of lanthanum,ethylenediamine tetraacetic acid( EDTA) and La in cooperation with EDTA on the structure and hydrodesulfurization performance of the catalysts were investigated. The catalysts were characterized byXRD,BET,H2 -TPR and SEM. The results indicated that La and EDTA could weaken the interaction between support and active component, facilitate the reduction of active component, and benefit the formation of Ni-W-S phase. Addition of La or EDTA could increase the surface area and suppress the agglomeration of active metals on surface,forming smaller and highly dispersed active phase particles. The La,EDTA and combined La and EDTA modified catalysts possessed higher HDS activity than Ni-W sample,Ni-W-La-E catalyst had the highest HDS activity,and its thiophene conversion reached 99 . 7%.%采用等体积浸渍法制备了以TiO2-Al2O3为载体,Ni、W为活性金属组分的加氢脱硫催化剂,考察了稀土金属镧(La)、乙二胺四乙酸(EDTA)改性以及La-EDTA组合改性对催化剂结构和加氢脱硫性能的影响.通过X射线衍射、N2吸附-脱附、H2-程序升温还原和扫描电子显微镜对催化剂进行表征分析.结果表明,La和EDTA均可改善活性组分与载体间的相互作用,增加了Ni-W-S活性相的数量,有利于金属组分的还原;同时能够丰富催化剂孔道,抑制催化剂表面金属离子聚集,得到更好的孔结构、更高的活性相分散度.La或EDTA以及两者同时改性后的催化剂噻吩硫脱除率均明显高于未改性催化剂,其中Ni-W-La-E催化剂上噻吩转化率为99.7%.