Catalytic Deoxygenation Of Wucaiwan Long Flame Coal Using NiO/Mo₂O₃-ZSM-5

The content of oxygen in Wucaiwan long flame coal is high,which is mainly in carbon oxygen bridge bond structure.Selectively cleaving C-O bridged bond can remove the oxygen-containing functional groups.The supported catalyst?NiO/Mo₂O₃-ZSM-5?was prepared by incipient-wetness impregnation method and the source of the active component was Ni?NO₃?₂ and?NH₄?₆Mo₇O₂₄?4H₂O.The catalyst was characterized by SEM,EDS,XRD,BET,XPS and NH3-TPD.It revealed that the load of active component was low,and well dispersed on the surface of molecular sieve.NiO/Mo₂O₃-ZSM-5 had large specific surface area and mesoporous structure.The active components had strong interaction with the support material.Benzyl ether was used as the coal-related model compound to evaluate catalytic activity.The results showed that the reaction temperature,reaction time and catalyst feed effectively influenced on catalytic deoxygenation reactions,but initial H₂ pressure was insignificant.The WCW long flame coal was subjected to non-catalytic deoxygenation and catalytic deoxygenation over NiO/Mo₂O₃-ZSM-5 sequentially in cyclohexane,toluene,ethanol and isopropanol under pressurized hydrogen at 300 ?.The reaction mixtures were analyzed with a gas chromatography/mass spectrometer?GC/MS?and an Orbitrap mass spectrometer?Orbitrap MS?.The GC/MS analytical results revealed that catalytic deoxygenation yields was higher than non-catalytic deoxygenation yields,and the catalyst could remove the oxygen of some O-contained compounds?esters,ketones et al.?,but did not work well on phenols.For Orbitrap MS with negative ion mode,the weighted mean DBE values for O₂ and O₃ classes species reduced 1.9 and 1.8 after catalytic reactions,the weighted mean carbon numbers reduced 4.2 and 3.9 respectively,it is suggested that ring opening reactions may occur during catalytic treatment.The results of Orbitrap MS suggested that the catalyst can effectively remove the oxygen in CnHn O4-6 class species,however,it can not work well in C_nH_nO₁ class species.The possible reason is Cn HnO₂-10 decomposed to C_nH_nO₁ with the action of NiO/Mo₂O₃-ZSM-5.The reactions of several coal-related model compounds showed that carbon-oxygen?C-O?bond in model compounds can be specifically cleaved over Ni O/Mo2O₃-ZSM-5.Acidity of the catalyst facilitated heterolytical splitting of H₂ to an immobile H-adhered to the NiO/Mo₂O₃-ZSM-5 surface and a mobile H⁺.The mobile H⁺ added to the position leading the cleavage of C-O bond.The generation of H+ was the key step of the catalytic reactions.Herein the reaction mechanism of coal deoxygenation can be derived from the reactions of model compounds.