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Graphical abstract The PEL process ((a) sawdust and cellulose, (b) corn cob and holocellulose, (c) corn stalk and lignin, (d) rice straw, (e) brief schematic diagram of PEL experimental apparatus, (f) gas product, (g) liquid product, (h) solid residue). Highlights • Discharge characteristics and catalytic efficiency of four catalysts were compared. • The liquefaction yield of sawdust reached 97.20% in 2 min. • A high liquefaction yield was obtained in the presence of a salt catalyst. • Cellulose, holocellulose, and lignin were extracted and liquefied successfully. • Plasma electrolytic technology could successfully liquefy lignocellulosic biomass. Abstract In this research, we compared the discharge characteristics and catalytic efficiency of sulfuric acid, p-toluenesulfonic acid, and their respective sodium salts (sodium sulfate and sodium p-toluenesulfonate) in sawdust liquefaction and found that sulfuric acid was the optimal catalyst when glycerol was used as solvent during the plasma electrolytic liquefaction (PEL) process. When sodium p-toluenesulfonate was used as the only catalyst, the liquefaction yield reached 83.51% after 25 min. This yield was higher than that obtained using sodium sulfate as the catalyst (60.63%) because different concentrations of H ions were produced in PEL. Cellulose, lignin, and holocellulose were extracted from sawdust and successfully liquefied in PEL, illustrating the universality of PEL. The optical emission spectra of the different biomass during the PEL process were similar, indicating that the kinds of free radicals produced were similar, which can accelerate the liquefaction of sawdust. [ABSTRACT FROM AUTHOR]

In this work, plasma electrolytic technology was successfully employed to achieve fast liquefaction of sawdust when polyethylene glycol 200 (PEG 200) and glycerol were used as liquefacient in the presence of the catalyst sulfuric acid. Results showed that H ions could heat the solution effectively during the plasma electrolytic liquefaction (PEL) process. The influence of some key parameters including liquefaction time, catalyst percentage, liquefacient/sawdust mass ratio, and PEG 200/glycerol molar ratio on the liquefaction yield were investigated. Based on the results of single factor experiments, response surface methodology (RSM) was applied to optimize the liquefaction process. Under the optimal conditions that is liquefaction time of 5.10 min, catalyst percentage of 1.05%, liquefacient/sawdust mass ratio of 7.12/1 and PEG 200/glycerol molar ratio of 1.40/1, the liquefaction yield reached 99.48%. Hence, it could be concluded that PEL has good application potential for biomass fast liquefaction. [ABSTRACT FROM AUTHOR]