Plasma-Enabled Fast Liquefaction of Lignocellulosic Biomass: Impact of Biomass Feedstocks

Biomass liquefaction is a way for transform the renewable biomass into high-grade fuels and chemicals. Plasma liquefaction is one of the most promising ways for energy conversion and utilization through highly-reactive chemistry which helps convert biomass into valuable energy carriers^{1, 2}. However, biomass dramatically ranges in the feedstock content of hemicelluloses, cellulose, lignin, and ash. Here, we performed the liquefaction of three typical lignocellulosic materials (sawdust, corncob and rice straw) with different feedstock contents using the plasma-enabled liquefaction (PEL) process. The sulfuric acid and the mixture of the polyethylene glycol 200 and glycerol were used as the catalyst and the liquefacient, respectively. The influence of the catalyst content and the reaction time on the degradation of each biomass was investigated to understand the effect of feedstock content on the liquefaction yield. It is shown that corncob were completely liquefied into crude bio-oil under the following optimal conditions- 5 g corncob, 1.5% catalyst volume percentage, 7/1 liquefacient/corncob mass ratio, 3 min reaction time, and 1.38 molar ratio of PEG 200 and glycerol. Based on the chemical element analysis of biomass samples and the associated liquefied samples coupled with a comprehensive analysis of their FTIR and GC/MS results, the chemical contents of the lignecellulosic biomass especially the amount of lignin and ash significantly influenced the liquefaction yield, the quality of liquid products and the distributions of the liquefied chemicals. The maximum energy yield (liquid fuels) were achieved in the plasma-enabled liquefaction of sawdust having the highest content of lignin. The PEL process in this work is a promising approach for biomass liquefaction with higher liquefaction rate and energy efficiency.