Hydroconversion Of Cellulose To Hexitols Over Mesoporous Ru/ZSM-5

Cellulose is one of the most abundant biomass resources in nature. Catalyticconversion of cellulose to fuel chemicals and fine chemicals is one of important waysto utilize biomass resources. The solid acid catalysts are widely used in the conversionof cellulose. In this paper, mesoporous Ru/HZSM-5zeolite prepared by alkalinetreatment was applied to catalytic conversion of cellulose to sugar alcohols.Zeolite was treated by NaOH solution with different concentrations. The preparedalkaline treated zeolites were characterized by X-ray diffraction (XRD), N2physisorption, scanning electron microscope (SEM), temperature programmeddesorption of ammonia (NH3-TPD) and FTIR of pyridine adsorption. Thecharacterization results indicate that alkali treated samples have obvious mesoporousstructure (7-20nm). Macroporous structure of100nm was produced when higherNaOH concentration was used. Meanwhile, Alkali treatment has a greater impact onthe total acid amount of zeolites. Lewis acid sites (LASs) increased and Bronsted acidsites (BASs) decreased over the alkali treatment samples.Ru/ZSM-5catalyst was prepared by impregnation method, The characterizationresults show that Ru/ZSM-5catalyst still retains the mesoporous structural propertiesof mesoporous support. The amount of acid of ruthenium catalyst showed a consistenttrend with support. TEM and H2-TPR showed that the larger surface area and porevolume result in ruthenium highly dispersed on the zeolite surface.Mesoporous Ru/HZSM-5zeolite prepared by alkaline treatment was applied tocatalytic conversion of cellulose to sugar alcohols. The results showed that theoptimal reaction conditions are: cellulose0.5g,0.5AT-Ru catalyst0.1g, at200℃,5MPa H2,10h. The conversion of cellulose reached63.4%and the yield of sorbitolwere39.4%.We investigated hydrolysis and hydrogenation reactions of the cellobiose, thestudies show that Lewis acid sites favorate the hydrolysis of oligosaccharides, therebyimproving the catalytic activity of cellulose conversion. Larger pore structure benefitsreaction-diffusion of reactants and products, reducing side reactions. The smallerruthenium metal particles significantly improve the performance of hydrogenation.The used catalyst was characterized by XRD, BET, ICP. The results show that catalyst deactivation is mainly due to the destruction of the catalyst framework. The decreasedspecific surface area and crystallinity of the catalyst results in a lower catalyticactivity.