Synthesis, Charaterization And Quinoline Hydrodenitrogenation Performance Of Molybdenum Carbide

With the petroleum becoming inferior and environmental regulations growing stringent,new high-performance hydrodesulfurization and hydrodenitrogenation catalysts in hydrotreating field has become a new hotspot.Molybdenum carbide catalysts were prepared by temperatureprogrammed reaction and characterized by XRD,BET,SEM,XPS techniques.TG-DTA in-situ was used to investigate the synthesis mechanism of molybdenum carbide catalysts.The hydrodenitrogenation(HDN) performance of the catalysts were evaluated by using of quinoline/cyclohexane as model reactants.The results were as follows:MoO₃ could be carburized intoβ-Mo₂C in CH₄/H₂ mixture at carburizing temperature 675℃.The promoters Ni and Co could change the process of carburization,decrease the carburizing temperature and increase the surface area of Mo₂C.Ni could reduce it's initial and terminal carburizing temperature,while Co could merely increase the initial temperature,but couldn't effect the terminal carburizing temperature.Mo₂C had a higher activity of quinoline HDN than MoS₂ and MoO₃.Under the reaction conditions of 340℃,3.0MPa,space velocity 8h^-1,and H₂ / liquid volume ratio 500:1,the quinoline HDN activity of Mo₂C reached 41.3 percent,which was about 8 percent point and 24 percent point higher than that of MoS₂ and MoO₃,respectively. The quinoline HDN activity of Ni-Mo₂C at 0.3 of Ni/Mo atom ratio and Co-Mo₂C at 0.4 of Ni/Mo atom ratio reached 98.2%and 98.0%under the same reaction conditions,which was about 47 percent point higher than that of Mo₂C.It was found that Ni and Co promoters could significantly improve the quinoline HDN activity of Mo₂C.The optimal preparation conditions for Ni-Mo₂C were that the carburizing temperature was about 625℃,while for Co-Mo₂C that was 650℃,and the carburizing time was 180 min for both.