Hydrolysis Of Lignocellulosic Biomass To Furfural And Levulinic Acid

The platform chemicals of furfural and levulinic acid can be obtained by hydrolysis of lignocellulose. These chemicals play an important role in chemical, medicine and energy fields. To realize the efficient utilization of biomass, this paper showed some research on conversion of hemicellulose to furfural and cellulose to levulinic acid.Furfural is mainly produced from hemicellulose through hydrolysis and dehydration. The furfural yield of 33.78% was obtained under the optimum conditions of liquid-solid 2:1,170℃, sulfuric acid 0.5mol/L. To improve reaction rate, the effects of three different Lewis acids (FeCl3, AlCl3·6H2O, ZnCl2) were compared under above optimum conditions, and the results was in the order of FeCl3>AlCl3·6H2O>ZnCl2. Through optimizing the dosage of FeCl3, a higher yield of 42.48% was obtained under the conditions of 2:1 liquid-solid,170℃,0.5mol/L sulfuric acid and 0.15mol/L FeCl3. The thiourea was added in reaction to reduce furfural side-reactions, and the highest yield of 47.59% was obtained with 16.45mmol/L thiourea.Side-reactions were the main reason for low yield of furfural. This paper showed some research on inhibition effects of thiourea under three different temperatures of 160℃,180℃ and 200℃, and the results showed that the degradation rates with thiourea decreased by 6.82%, 12.80% and 7.35% respectively compared with that without thiourea. The furfural degradation reaction was first-order reaction through fitting the experimental results, and the addition of thiourea made reaction activation increase from 28.69 kJ/mol to 34.72 kJ/mol. The results proved the inhibition effect of thiourea on furfural degradation.There were much more cellulose in furfural residues, and levulinic acid can be obtained at high temperature by acid hydrolysis. To achieve high levulinic acid yield, many factors were investigated, including Lewis acids (FeCl3·6H2O, LiCl·H2O, AICl3·6H2O, ZnCl2), dosage, temperature and concentration of sulfuric acid. And the highest yield of 59.63% was obtainted under the conditions of FeCl3·6H2O of 0.09mol/L,200℃, sulfuric acid of 0.3mol/L and residue time of 40 min.