Study On Hydrogenation Of Biomass Derivatives To Prepare High Value-added Chemicals

Fossil energy(oil,coal,natural gas)has always been the major source of fuels and chemicals.However,because of the depletion of fossil energy and the deterioration of the environment,looking for a renewable alternative green energy resource has become an important topic for contemporary researchers.As a sustainable and renewable resource,biomass can be degraded into liquid bio-oil and a variety of valuable chemicals.These chemicals include glucose,ethanol,carboxylic acids,furfural(FF),5-hydroxymethylfurfural(HMF),2,5-dimethylfuran,levulinic acid(LA),ethyl levulinate(EL),?-valerolactone(GVL)etc..Following the principle of biomass energy development that “does not compete with people”,it is considered to have far-reaching significance to convert lignocellulose-rich wastes such as crop straw and forestry waste into valuable fuels and chemicals.Levulinic acid is an important platform compound derived from the degradation and conversion of lignocellulose and is an important intermediate for the comprehensive utilization of lignocellulose.Levulinic acid can be used as a chemical intermediate to prepare a variety of higher value-added compounds,the most valuable of which is ?-valerolactone.In addition,lignin,an important component of lignocellulose,is the only component of biomass that has aromatic structures.Therefore,lignin has high application potential in the production of aromatic chemicals.In this work,a variety of metal-supported catalysts and novel porous metal organic framework materials were prepared and investigated in the hydrogenation of the above biomass derivatives.At the same time,different hydrogenation processes were optimized.Specifically,the main work of this article is as follows:(1)The catalyst material with uniform dispersion of nickel particles was prepared by using activated carbon as support.The influence of the temperature of the catalyst on the dispersion and hydrogenation reaction was analyzed.In addition,a variety of supported cobalt-based catalysts were prepared and applied to the hydrogenation of levulinic acid.The activity of the support for the hydrogenation of levulinic acid and the deep hydrogenation of ?-valerolactone were investigated.The effects of hydrogenation reaction conditions were also analyzed and optimized.(2)Ethyl levulinate was efficiently converted to ?-valerolactone via catalyzed hydrogen transfer(CTH)of carbonyl group,using novel zirconium/niobium-based metal organic framework materials(Zr-/Hf-DUT67)as catalysts,and small molecule alcohols instead of hydrogen as the hydrogen donor.The catalytic hydrogen transfer reaction process does not require high-pressure hydrogen,so the reaction conditions are milder,the operation process is simpler.and because of the targeted hydrogenation of the carbonyl group,further hydrogenation of the product ?-valerolactone to avoid by-products is avoided.Since the CTH process is only effective for the carbonyl hydrogenation,further hydrogenation of the product ?-valerolactone to by-products is avoided.(3)Because of the complex structure of lignin and numerous degradation products,guaiacol was selected as a model compound for catalytic hydrodeoxygenation.The molybdenum dioxide catalyst and the molybdenum carbide catalyst were prepared using different reduction temperatures,and the catalytic activities of the two catalysts in the hydrodeoxygenation of guaiacol were investigated and compared.Catalyzed by molybdenum dioxide material,guaiacol was converted to phenol and cresol with high selectivity at a temperature of 300? and 3 MPa of hydrogen for 3 hours.In contrast,the molybdenum carbide catalyst has stronger hydrogenation activity and can further hydrogenate phenol and cresol to produce benzene and toluene.In addition,the hydrodeoxygenation reaction route of guaiacol was deduced by analyzing the hydrodeoxygenation product distribution of the reactants and intermediates.