钇和柠檬酸对非负载磷化镍催化剂加氢脱硫性能的影响

采用传统程序升温(TPR)法制备了稀土金属钇(Y)或柠檬酸(CA)改性及Y和CA同时改性的非负载型Ni2P催化剂;采用X射线衍射(XRD)分析、N2吸附比表面积(BET)测定、CO化学吸附分析、X射线光电子能谱(XPS)和透射电子显微镜(TEM)对催化剂的结构和性质进行了表征;并考察了Y和CA对催化剂上进行的二苯并噻吩(DBT)加氢脱硫(HDS)反应性能的影响.结果表明,Y和CA均可促使非晶相NixPyOz向磷化镍活性相的转化,抑制Ni_5P_4杂晶相的形成,从而促进Ni2P活性相的生成;同时能够丰富催化剂的孔道,抑制催化剂表面磷的富集,得到更好的孔结构、更高的活性相分散度.Y或CA以及两者同时改性后的催化剂DBT转化率均明显高于Ni-P催化剂.各催化剂的HDS活性大小顺序为Y-Ni-P-CANi-P-CAY-Ni-PNi-P.在340℃,3.0 MPa,氢油体积比700,质量空速(WHSV)1.5 h-1的条件下,Y-Ni-P-CA催化剂的DBT转化率为97%,比Ni-P催化剂提高了约35%.

Effect of Yttrium and Citric Acid on the Hydrodesulfurization Performance of Unsupported Nickel Phosphide

The Yttrium ( Y ) , citric acid ( CA ) and combined Y and CA modified bulk nickel phosphide ( Ni-P) catalysts were prepared by temperature programmed reduction ( TPR ) method. The catalysts were characterized by means of X-ray diffraction( XRD) , N2-adsorption specific surface area measurements( BET) , CO chemisorption uptake measurements, X-ray photoelectron spectroscopy ( XPS ) and transmission electron microscopy(TEM). The effects of Y and CA on catalyst activity for dibenzothiophene(DBT) hydrodesulfuriza-tion(HDS) were studied. The results indicated that both Y and CA can promote the transformation from NixPy Oz amorphous phase to nickel phosphide active phase, suppress the formation of Ni5 P4 phase and therefore promote the formation of Ni2 P active phase. Addition of Y or CA can increase the surface area and suppress the enrichment of phosphorus on surface, leading to a smaller and highly dispersed active phase particles. The Y, CA and combined Y and CA modified nickel phosphide catalysts were proved to possess higher HDS activi-ty than Ni-P sample. The DBT conversions of catalysts followed the order: Y-Ni-P-CA>Ni-P-CA>Y-Ni-P>Ni-P. At the conditions of 340℃, 3. 0 MPa, WHSV of 1. 5 h-1 and H2/oil volume ratio of 700, the DBT con-version of the Y-Ni-P-CA catalyst reached 97%, which is an increase of 35% when compared with that found for bulk Ni-P sample.