Research On The Preparation Of Furan Derivatives And Biobased Carbon Materials From Agricultural And Forestry Wastes

In this paper,agricultural and forestry waste as raw materials,combined with chemical catalysis,hydrothermal conversion and pyrolysis technology on the use of biomass and activated carbon selective oxidation were studied.At first,a new path of direct conversion of agricultural and forestry wastes into furan derivatives was proposed,and a new idea of reuse of solid waste residues after biomass conversion was proposed,and the reaction of levulinic acid oxidation catalyzed by biomass activated carbon was designed.(1)The integration and cascade utilization of the entire lignocellulosic biomass components to obtain high value-added chemicals or fuels are of high interest.Herein,a strategy combined the chemo-catalytic and hydrothermal liquification processes was developed for the conversion of raw biomass into high value-added furanic compounds and fuels.Firstly,optimal 58% yield of furfural and 40% yield of5-methylfurfural were co-produced from hemicellulose and cellulose components of hemp stalk powder(HSP)using formic acid and Na I as the catalysts.Then,the lignin-rich solid residue left after chemo-catalytic process,can be simply converted into bio-oil and hydrochar via hydrothermal liquefaction with a high energy recovery efficiency(88%).Elemental analysis of the bio-oils and hydrochars,as well as the adsorbing capacity of the hydrochars were also investigated and discussed.(2)Various functional carbons can be produced from biomass with high cellulose and hemicellulose content by(partial)pyrolysis or hydrothermal carbonization.This project found that activated carbon prepared by biomass can be synergistic catalyzed with calcium oxide to oxidize levulinic acid to produce2-hydroxy-2-methylsuccinic acid,with a selectivity of up to 94%.The factors affecting the catalytic activity of activated carbon were systematically studied and analyzed from the aspects of elemental analysis,pore structure,adsorption relationship and EPR.It was found that nitrogen doping could increase the catalytic activity of activated carbon,and biomass based activated carbon with high nitrogen content had better catalytic activity.Alkali activation can improve the pore structure of catalyst and enhance its chemical catalytic activity.The mesoporous structure of carbon-based catalyst is the key to the transfer of reactants and active intermediates,but the strong adsorption of levulinic acid by the microporous structure of carbon material hinders the reaction.Calcium oxide has affinity to reactive oxygen species produced by activated carbon.In addition,the catalyst of calcium oxide/carbon(Ca O/MC)composite structure was synthesized by simple calcination of calcium citrate.Calcium oxide showed highly uniform dispersion in heterogeneous structures,with a mesoporous/total pore volume of 98% and a selectivity of 81.9% for2-hydroxy-2-methylsuccinic acid.