The Fundmental Research On The Catalytic Liquefaction Of Waste Biomass In Hot-compressed Water

The main obstacle of lignocellulose biomass liquefaction for bio-oil and high added value chemicals is the low yield and low quality of the useful products and low conversion rate of lignin which is one of the main compounds of the biomass. Originally, in this research the alkaline catalyst and Al2O3 were used in the liquefaction process of biomass for bio-oil and useful chemicals. The purpose of this research is to improve the relative strict conditions of biomass liquefaction and enhance the conversion rate of lignin and the yields of bio-oil and valuable chemicals.In the research of biomass liquefaction, the study of reaction conditions as the base of further research is very necessary. The effect of reaction temperature on bio-oil yield was investigated. The total oil yield of straw liquefaction was 50.25% at 280℃, while the total oil yield of sawdust liquefaction was 35.96% at 320℃The composition of bio-oil was determined by materials and reaction conditions, straw more easily liquefied than sawdust at the same temperature.The catalysts used in this research were alkaline catalyst and Al₂O₃. The objective of the study is to investigate the effect of the catalyst on yield of bio-oil and the composition of bio-oil, and the differences catalytic effects between liquefaction of straw (cellulose) and sawdust (lignin) were compared. The effects of each catalyst on the yields of products were different. The yields of bio-oil were enhanced, and the compositions of all kinds of bio-oil were changed. In the run with alkaline catalyst (NaOH), the residue yield of sawdust liquefaction was reduced from 20.87% to 1.26%, and the yield of Oil1 was enhanced from 3.40% to 11.87%. The gas chromatography/mass spectrometry (GC-MS) analysis showed that the benzenediol derivatives were increased in Oil1 with KOH. In the run with Al2O3 catalyst (0.4 g) the maximum bio-oil yield was obtained as 20.83%. Meanwhile the minimum residue yield of 12.50% was obtained at the reaction temperature 280°C and 0.3 g Al2O3. The gas chromatography/mass spectrometry (GC-MS) analysis showed that the main difference between bio-oil with or without catalyst liquefaction were the presence of heneicosane and the decrement of other oxygenous compounds.In summary, the decomposition of biomass was improved with catalysts. The strict conditions of biomass liquefaction was reduced, the conversion rate of lignin and the yields of bio-oil and valuable chemicals were enhanced with alkaline catalyst and Al₂O₃.