Hydrogenation and Ring Opening Catalytic Performances of Hβ Supported Mo-Based Phosphide and Sulfide
The supported MoP as well as Mo and NiMo sulfide catalysts were prepared using Hβzeolite as the support(denoted as MoP/Hβ,MoS2/Hβ,and NiMoS2/Hβ,respectively),which were characterized by techniques such as X-ray diffraction(XRD)and pyridine-adsorbed infrared spectrometry(Py-IR).The hydrogenation and ring opening performances of the catalysts were evaluated using decalin as the model compound at the temperature of 310 ℃,H2 pressure of 4.0 MPa,mass hourly space velocity(MHSV)of 3.2 h-1 and hydrogen/oil volume ratio of 1000.The analysis and characterization results show that the acidities of MoP/Hβ,MoS2/Hβ,and NiMoS2/Hβ are lower than that of Hβ.The performance evaluation results of ring opening reactions demonstrate that both the activity and stability of MoP/Hβ are superior to those of MoS2/Hβ and NiMoS2/Hβ.The quick deactivation of sulfide catalysts at the beginning of the ring opening of decalin is due to a decrease in their hydrogenolysis activity.The metal and acid sites are likely all involved in the ring contraction and ring opening of decalin.The ring opening of decalin occurs mainly through the ring contraction pathway,and the direct hydrogenolysis of decalin catalyzed by metals is a minor pathway.The metallocyclobutane mechanism is preferred for the hydrogenolysis of decalin over all the catalysts studied.Compared with the situation over MoS2/Hβ,the hydrogenolysis of decalin is more likely to occur over MoP/Hβ and NiMoS2/Hβ by means of metallocyclobutane mechanism.
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