An Investigation On The Hydrodesulfurization Performance Of NMoO_x·USY

A series of nWoOx-USY,nCoMoOx·USY12 and nNiMoOx·USY12 single-phase complex were prepared by incipient wetness impregnation and solid-state reaction,and characterized by XRD,BET,NH3-TPD and SEM techniques.The hydrodesulfurization performance of catalysts were evaluated by using dibenzothiophene/n-decane as model reactant.The results indicated that there were no diffraction peaks of MoO3 in the XRD patterns of MoOx·USY,nCoMoOx·USY12 and nNiMoOx·USY12,and the diffraction peaks attributed USY were well-preserved.The catalysts were prepared by using solid-state reaction of MoOx with USY,MoOx located in USY molecular sieve cage in the form of molybdenum-oxygen clusters.It induced the contraction of the USY molecular sieve lattice cell,the decrease of the lattice parameters a0 and specifics surface area of the nMoOx·USY,nCoMoOx·USY12 and nNiMoOx·USY12.During the preparation of nCoMoOx·USY12 and nNiMoOx·USY12,a part of Co and Ni entered the βcage of USY molecular sieve in the form of Com+and Nin+,and replaced H+existed in β cage,induced the expansion of the USY molecular sieve lattice cell and increase of the lattice parameters a0.Because the MoOx of nMoOx·USY single-phase complex could adsorb and polarize water molecules,and accept electronics,it could generate acid sites especially weak acid sites and increase the total acid sites.The increase of calcination temperature,dosage of Mo and citric acid,calcination time could be beneficial to the formation of nMoOx·USY single-phase complex.The dibenzothiophene conversion of nMoOx·USY0 prepared with dosage of Mo 5.0m%reached to 40.28%,84.67%and 97.56%under the reaction conditions of 4.0MPa,space velocity 20h-1 and H2/oil volumetric ratio 600:1 at 270℃,290O℃and 310℃ reaction temperature,which better than that of Mo/γ-Al2O3 prepared with 20.0m%Mo.The catalysts had better hydrodesulfurization performance prepared at the calcination conditions of 520℃,4h,dosage of Mo 8.0m%,Ni/Mo,Co/Mo molar ratio 0.3,first pyrolysis and then calcination step.The DBT desulfurization reaction of the MoOx·USY,nCoMoOx·USYi2 and nNiMoOx·USY12 was dominated by the hydrogenation route.