Influence Of Sulfidation On Hydrodenitrogenation And Hydrodeoxygenation Performance Over Bulk MoP

The metal-rich transition-metal phosphides?e.g.Ni₂P,MoP,and WP?have proved to be high-activity catalysts for many reactions,such as hydrofining,hydrogenation/dehydrogenation and hydrogen evolution.The phosphide catalysts are superior to the sulfide catalysts not only because of their higher activity,but also of their unique behaviors in the HDS reactions.That is,The HDS activity of the phosphide catalysts usually increase monotonically as a function of time on stream during the first several hours.There would be formed new active sites during the HDS of dibenzothiophene?DBT?over bulk MoP,which possessed a higher direct desulfurization activity than the sites on the surface of fresh MoP catalyst.C–N bond and C-O bond cleavage activity of MoP catalyst pretreated by H₂S and methyl disulfide?DMDS?were evaluated using decahydroquinoline?DHQ?as nitrogen-containing molecule and dibenzofuran?DBF?as oxygen-containing molecules,respectively.Both sulfidation with H₂S and DMDS gave positive influence on the HDN performance over MoP,which enhanced the dehydrogenation and C–N bond cleavage activity.Sulfidation with H₂S under 300 ^oC of MoP had batter effect on C-N bond cleavage and dehydrogenation activity of DHQ and PCHE than 340 ^oC,and sulfidation with H₂S improved obviously the dehydrogenation activity of decalin and 1-methyl-1-cyclohexene.The sulfidation effect of DMDS was most obvious under high concentration?4.0 wt.%?and high hydrogen pressure?4MPa H₂?.The sulfidation effects of adding DMDS to DHQ depended on the concentration of DHQ and DMDS,but in all conditions,sulfidation of adding DMDS was benefited to the dehydrogenation activity of DHQ and PCHE.The HDO of DBF mainly went through the hydrogenation pathway over MoP,and the HDO of 2-cyclohexylphenol?CHPOH?was fast.The HDO of CHPOH went by three pathways:hydrogenation,direct deoxygenation and bicyclic hydrocracking.Phenol,much cyclopentylmethylcyclohexane?CPCM?and cyclohexane?CH?were found in the products of DBF and CHOPH.CPCM might come from the isomerization the hydrogenation product of CHPOH.CH was derived from the CHPOH bicyclic hydrocracking and the HDO reaction of phenol.MoP pre-treated by oxygen and H₂S were barely good for the hydrogenation of DBF,but both increased the CHPOH bicyclic hydrocracking activity.Sulfidation of MoP enhanced the oxygen resistance of MoP.