Preparation Of Transition Metal Phosphide By In-situ Phosphating And Catalytic Performance In Hydrogenation

Transition metal phosphides have rapidly become a field of research hot spots in hydrogenation catalysis due to their high catalytic hydrogenation performance.However,the existing preparation methods of phosphide catalysts generally have problems such as high phosphating temperature and complicated preparation process,which greatly limits the industrial application of the catalyst.Therefore,this paper prepared a series of transition metal phosphide?CoP,MoP and Ni₂P?using triphenylphosphine in-situ phosphating process.The effects of phosphating conditions on the hydrodesulfurization performance of the catalyst were investigated,and the phosphating process of different active metal was preliminarily studied.This will provide theoretical direction for the design of new type of hydrogenation catalysts.The catalyst precursor of SiO₂ supported was prepared by saturated impregnation method.Then,we used triphenylphosphine as phosphorus source and operated in situ phosphatization on precursor in continuous high pressure microreactor,and investigated the effects of phosphating temperature and phosphating time on the preparation of the catalyst.The results show that all the kinds of catalyst can phosphate under the condition of 4 hours phosphating time,but the phosphating temperature required to complete the phosphating was different.CoP and Ni₂P can phosphate at 300?,while MoP needs 450?to phosphate,which is due to the different phosphating process.Co₃O₄ phosphorylation process is relatively simple,Co₃O₄ is reduced to CoO,and then CoO is directly generated by phosphating CoP.the phosphating process of MoO₃ mainly includes the following steps:MoO₃ is first reduced to MoO₂;MoO₂ is further reduced to produce MoO_x?0<x<2?;MoO_x?0<x<2?is phosphogens to produce MoP,and and there is by-product MoP₂O₇ formation.The HDS reaction performance of the three catalysts was investigated by using DBT toluene solution whose mass fraction is 2%.The results show that the three catalysts have a good catalytic hydrodesulfurization performance,in which the maximum conversion of DBT on Ni₂P and CoP was above 90%,while that of MoP was relatively low.In the HDS reaction products,the selectivity of biphenyl is more than 50%,and the reaction path is dominated by direct desulfurization?DDS?.