Catalytic Conversion Of Cellulose Into Low-carbon Polyols Over Ru-supported Catalyst

With the rapid development of social economy, the global demand for energy is increasing and the non renewable energy resources are on the verge of crisis. The research of the use of biomass resources into chemicals and fuels is getting more and more attention. Cellulose, the most abundant biomass energy resources in nature, can be converted by catalytic conversion into sorbitol, mannitol, ethylene glycol, 1,2-propanediol and a series of low-carbon polyols.. These multiple alcohols can be further transformed into important industrial biological platform compounds, which is important for the sustainable development of human society.In this paper, microcrystalline cellulose was chosen as raw material, metal catalysts are prepared by impregnation method. The catalytic conversion of cellulose into low-carbon polyols is achieved in a relatively mild condition. The conclusions are as follows:(1) A series of supported metal catalysts are prepared by impregnation method. The influences of the supporter, active metal component, reaction temperature and reaction time on the catalytic performance of the catalyst are investigated. The results showed that the carbon nanotube supported Ru as a catalyst has good catalytic performance and the reaction temperature and reaction time have an important influence on the catalytic conversion of cellulose. The catalytic performance of Ru/CNTs and Pd/Al2O3 on the catalytic conversion of glucose and cellobiose are investigated, glucose and cellobiose can be completely degraded and the yield of sorbitol can reach 52.8% and 32.3%, respectively, on Ru/CNTs、Pd/Al2O3 after 0.5 h, at 200 ℃ and 6.0 MPa H2 pressure.(2) A series of bimetallic supported catalysts are prepared by using carbon nanotube as the supporter and SnCl2 was chosen as modifier. The effects of active metal component and metal atom ratio, reaction time, reaction temperature, pressure of H2 and catalyst dosage on the catalytic conversion of cellulose are optimized. The results showed that the conversion of cellulose on the Ru-Sn(0.3)/CNTs is 75.63%and the yield of sorbitol is 22.17% at 200 ℃ after 0.5 h,. The optimum reaction conditions of Ru-Sn/CNTs catalyst for conversion of cellulose are: the reaction temperature is 220 ℃, the reaction time is 60 min, the H2 pressure is 6.0 MPa, the catalyst dosage is 0.4 g(cellulose dosage is 1.0 g.).The yields of C2~C3 and C6 sugar alcohol are 15.46% and 35.48% respectively..(3) Amberlyst-15, HZSM-5, WO3 and AC-SO3 H solid-acid catalysts are chosen to investigate theeffects of solid acids and bimetallic supported bimetallic catalysts on the conversion of cellulose. The results showed that amberlyst-15 has a certain promotion effect for the conversion of cellulose. When Amberlyst-15 and Ru/Al2O3 catalysts are used to catalyze the conversion of cellulose, the conversion of cellulose are 75.94%. The conversion of cellulose increased about 23.55% and 55.41%, respectively,compared to the Ru/Al2O3 catalyst and the non catalyst on the catalytic conversion of cellulose. The yield of the polyols is also significantly improved. Amberlyst-15 exhibits excellent catalytic performance in the catalytic conversion of cellulose, especially for the yield of glycerol.(4) The catalysts are characterized by IR, XRD, TEM and BET. The results showed that active metal had good dispersion on the surface of the CNTs. BET results showed that the specific surface area, pore volume and pore size of the catalyst decreased with the increase of Sn and Ru content, which indicated that the Ru and the Sn species might locate in the inner surface of the CNTs pores and the limiting effect of the channel will be helpful for preventing metal sintering.