Synthesis And Catalytic Performance Of Co-Mo-S Catalysts For Hydrodeoxygenation

The disadvantages of non-renewable and high pollution of fossil energy make it extremely urgent to seek a new type of green and renewable energy.Biomass energy reserves are abundant,green and renewable,and bio-oil obtained from biomass pyrolysis is a potential substitute for fossil energy.However,the high oxygen content of bio-oil leads to the disadvantages of low combustion calorific value,high viscosity and high corrosiveness,which greatly limits the use of bio-oil as a fuel.It has been reported in the literature that catalytic hydrodeoxygenation（HDO）technology can effectively remove oxygen-containing groups in biomass oil,thereby improving the oil quality of bio-oil.The development of efficient and economical catalysts is the key to HDO technology.The expensive cost of precious metal catalysts and the complex synthesis process of traditional sulfide catalysts limit their application in the actual production of bio-oil HDO.This paper mainly focuses on the following two problems existing in HDO catalysts.Aspects of work:Mo S₂ catalyst exhibits good activity in the HDO field.In this study,the Co-Mo S₂catalyst was prepared by precipitation,impregnation,and thermal decomposition of molybdenum trisulfide to release S to the sulfuration of Co oxide by utilizing the abundant sulfur vacancies in molybdenum trisulfide and its adsorption of Co ions.Mo molar ratio,the effects of different calcination temperatures on catalyst structure and activity under nitrogen atmosphere.The experimental results show that the Co-Mo-0.5-400 catalyst has the best HDO activity when the molar ratio of Co/Mo is 0.5and the calcination temperature is 400°C.In the HDO reaction of 4-methylphenol,after180°C for 9 h,the conversion rate reached 100%,and the selectivity of aromatic hydrocarbons reached 99.4%.The characterization results show that the high activity of the catalyst is related to the formation of highly dispersed Co sulfide and Co S-edge interface on the surface of molybdenum disulfide.It is worth mentioning that after enlarging the preparation scale of the catalyst by 200 times,the activity of the catalyst did not decrease significantly,and the catalyst showed excellent application prospects.The effects of different treatment methods on the catalyst activity were further investigated,and the Co@Co₉S₈-Mo S₂ catalyst prepared by calcining the Co-Mo S₂catalyst in a hydrogen atmosphere had the best catalytic activity.The experimental results show that in the HDO reaction of 4-methylphenol,the catalyst calcined at 400°C has the best HDO activity:the HDO reaction temperature of 4-methylphenol is reduced to the lowest temperature reported in the literature,120°C,the conversion rate reached 100%,and toluene The selectivity reached 99.9%.The phase composition and structure of the catalyst were analyzed by various characterization methods.The results show that the high activity of the Co@Co₉S₈-Mo S₂ catalyst is closely related to the metal cobalt element and the large number of sulfur vacancies on the surface of molybdenum disulfide after hydrogen calcination.related.In the universal study of more than 20 lignin oil model compounds including guaiacol and dimer,the catalyst still has high activity and high selectivity to aromatics.After recycling the Co@Co₉S₈-Mo S₂ catalyst for 8 times,the catalyst activity did not decrease significantly,showing good stability.