Preparation Of Supported Nickel Phosphide Catalyst And Its Hydrodesulfurization Performance Of Dibenzothiophene

The supported nickel phosphide catalysts were successfully prepared by solvothermal method and temperature programmed reduction of hypophosphite precursor method.The obtained catalysts were characterized by XRD,H2-TPR,N2 isothermal adsorption,FT-IR,XPS,TEM,SEM and CO uptake.The hydrodesulfurization(HDS)performance of catalysts was tested on a fixed bed and using the dibenzothiophene as model compound.The MCM-41,Al2O3,and TO2 supported Ni2P were successfully prepared by solvothermal method using the triphenylphosphine(PPh3)as the material.The results indicated that the formation of Ni2P phase favored the high synthesis temperature,and the formation of crystalline phase follows the order Ni,Ni2P5 and Ni2P with increasing synthesis temperature.The high initial P/Ni molar ratio favored the formation and dispersion of Ni2P phase,a mixture of Ni12P and Ni2P phase was observed in the sample with an initial P/Ni molar ratio of 0.5,and with the initial P/Ni molar ratio more than 6,the catalysts obtained showed high dispersion.The TiO2 supported Ni2P catalyst prepared by solvothermal method can keep the original structure of TiO2 and avoid the formation of TiPO4.The Al2O3 was not suited to nickel phosphide catalysts,because the AIPO4 can be formed during the preparation of catalysts.The hydrodesulfurization tests indicated that the dibenzothiophene conversions increased with increasing temperature.At the conditions of 613 K,3 MPa,H2/oil ratio of 500(v/v),and a weight hourly space velocity(WHSV)of 4 h-1,the catalysts with initial P/Ni molar ratio of 6 gave a activity with a dibenzothiophene conversion remained high at 100%within 120 h.During HDS reaction,a superficial NixPySz phase was formed on the surface of catalyst,which showed higher activity than Ni2P.A novel method for preparing the supported Ni2P/MCM-41 catalyst at low reduction temperature had been proposed.The results indicated that when the precursor with initial P/Ni molar ratio more than 1,the Ni2P catalyst can be obtained at a reduction temperature was 200 K lower than that of the traditional temperature program reduction(TPR)method.The formation of crystalline phase follows the order Ni,Ni12P5 and Ni2P with increasing reduction temperature.The catalyst with initial P/Ni molar ratio of 2 and reduced at 613 K showed higher HDS activity and stability,at the conditions of 613 K,3 MPa,H2/oil ratio of 500(v/v),and a weight hourly space velocity(WHSV)of 4 h-1,the conversion of DBT close to 99%and kept for 120 h without activity loss.