金属助剂对Ni_2P/SBA-15催化剂结构及二苯并噻吩加氢脱硫性能的影响

Effect of Metal Promoters on the Structure and Performance of the Ni_2P/SBA-15 Catalyst for Hydrodesulfurization

以介孔分子筛SBA-15为载体,硝酸镍为镍源,磷酸氢二铵为磷源,采用共浸渍法制备了P/Ni摩尔比为0.8的Ni2P/SBA-15催化剂,然后添加Li、Na、K、Mg、Ca、Sr和Ba等金属助剂,制备了一系列不同金属助剂的M-Ni2P/SBA-15(其中M为Li、Na、K、Mg、Ca、Sr和Ba)催化剂。采用XRD对该系列催化剂的结构进行了表征,并以二苯并噻吩质量分数为1%的二苯并噻吩/十氢萘溶液为模型化合物,在微型固定床反应器上评价它们的加氢脱硫(HDS)性能。结果表明,M-Ni2P/SBA-15催化剂的活性相为Ni2P。不同的金属助剂对催化剂性能的促进作用不同,其中碱土金属Ca能够明显地提高Ni2P/SBA-15催化剂的HDS活性,Ca质量分数为3.5%的Ca-Ni2P/SBA-15催化剂的HDS活性最好。在反应压力3.0 MPa、反应温度360℃的条件下,3.5%Ca-Ni2P/SBA-15催化剂催化的二苯并噻吩HDS的转化率达到98.6%。不同金属助剂以不同方式影响加氢脱硫反应的机理。

Ni2P/SBA-15 catalysts with initial P/Ni molar ratio of 0.8 were prepared by co-impregnation method with mesoporous molecular sieve SBA-15 as support,Ni（NO3）2·6H2O as a source of nickel and（NH4）2HPO4 as a source of phosphorus.Then,a series of M-Ni2P/SBA-15 catalysts were prepared by the addition of Li,Na,K,Mg,Ca,Sr,Ba metal promoters and characterized by X-ray diffraction（XRD）.The catalytic performance of the catalysts for hydrodesulfurization（HDS） was evaluated in a fixed-bed microreactor with the decalin solution of 1%（mass fraction） model compound dibenzothiophene.The results indicated that Ni2P particles were the active phase for M-Ni2P/SBA-15 catalysts.Different metal promoters（M） had different effects on the HDS performance of M-Ni2P/SBA-15 catalysts,among which the alkaline earth metal Ca was the best one to improve the HDS activity of the catalysts.Over the Ca-Ni2P/SBA-15 catalyst with Ca mass fraction of 3.5% the conversion of DBT HDS reached 98.6% under the conditions of reaction pressure at 3.0 MPa and temperature at 360℃.In addition,different metal promoters also affect HDS reaction mechanism in different ways.