title: Effect of residence time on two-step liquefaction of rice straw in a CO2atmosphere: Differences between subcritical water and supercritical ethanol.
abstract: This study investigated the influence of temperature and residence time on liquefaction of rice straw in subcritical CO2-subcritical water (subCO2-subH2O) and in subcritical CO2-supercritical ethanol (subCO2-scEtOH), considering the final reaction temperatures (270-345°C) and residence times (15 and 30min). Residence time was identified as a crucial parameter in the subCO2-subH2O liquefaction, whereas residence time had a marginal influence on subCO2-scEtOH liquefaction. When reaction conditions were 320°C and 15min, solvents have weak impact on the quality of bio-oil, HHV 28.57MJ/kg and 28.62MJ/kg, respectively. There was an obvious difference between the subCO2-subH2O and subCO2-scEtOH liquefaction mechanisms. In subCO2-subH2O, CO2promoted the carbonyl reaction. In subCO2-scEtOH, supercritical ethanol have the function of donating hydrogen and promoting the reaction of hydroxyl-alkylation.
authors.affiliation: Key Laboratory of Clean Energy of Liaoning, College of Energy and Environment, Shenyang Aerospace University, Shenyang 110136, PR China.
authors.forename: Tianhua
authors.initials: T
authors.lastname: Yang
authors.affiliation: Key Laboratory of Clean Energy of Liaoning, College of Energy and Environment, Shenyang Aerospace University, Shenyang 110136, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, PR China.
authors.forename: Bingshuo
authors.initials: B
authors.lastname: Li
authors.affiliation: Key Laboratory of Clean Energy of Liaoning, College of Energy and Environment, Shenyang Aerospace University, Shenyang 110136, PR China.
authors.forename: Xingping
authors.initials: X
authors.lastname: Kai
authors.affiliation: Key Laboratory of Clean Energy of Liaoning, College of Energy and Environment, Shenyang Aerospace University, Shenyang 110136, PR China. Electronic address: rdlee@163.com.
authors.forename: Rundong
authors.initials: R
authors.lastname: Li
mesh_terms: D056804:Biofuels / Q000032:analysis; D018533:Biomass; D001709:Biotechnology / Q000379:methods*; D002245:Carbon Dioxide / Q000737:chemistry*; D000431:Ethanol / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D008855:Microscopy, Electron, Scanning; D012275:Oryza / Q000737:chemistry*; D018520:Plant Shoots / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D056804:Biofuels; D012997:Solvents; D014867:Water; D002245:Carbon Dioxide; D000431:Ethanol
keywords: CO(2); Pretreatment; Subcritical H(2)O; Supercritical ethanol