Study On Distribution And Transformation Characteristics Of Major Inorganic Elements During The Liquefaction Process Of Biomass

Inorganics in biomass have migration and transformation abilities during the liquefaction process and distributed into the products. In addition, inorganics significantly affect the refinement and utilization of fuel. Therefore, the distribution and transformation characteristics of inorganic elements are very important factors which affect subsequent utilization of bio-oil. In this work, liquefaction of cornstalk for producing bio-oil was conducted with water(ethanol or acetone) as the solvent at temperatures of 280, 300, 320, 340 360°C and the distribution and transformation characteristics of inorganic elements K, Na, Mg, Ca, Al, and Fe during liquefaction were studied. The results demonstrated that liquefaction temperature and solvent clearly affected the distribution and transformation.The inorganic elements distributed mainly into bio-chars(>62.61%) with acetone(or ethanol) as liquefaction solvent, with less than 25.77% into the bio-oils; however, K and Na distributed mainly into aqueous phases with water as liquefaction solvent, and Ca, Al, and Fe distributed mainly into bio-chars, with less than 31% into the bio-oils. Increasing liquefaction temperature(320 to 360°C) could reduce the portion of inorganic elements in bio-oils. In addition, ICP-OES showed that the concentrations of inorganic elements in bio-oils were very high and also affected significantly by liquefaction temperature and solvent. The concentrations of K, Na, Mg, and Al in bio-oil obtained from water were higher than those obtained from acetone(or ethanol); however, the concentrations of Ca and Fe in bio-oil obtained from acetone were higher than those obtained from water(or ethanol).The inorganic elements existed in bio-chars with water as liquefaction solvent mainly in the form of residual(>40%) and the percentages of which increased as the liquefaction temperature increased. The inorganic elements K?Na?Mg?Al existed in bio-chars with acetone(ethanol) as liquefaction solvent mainly in the form of water-soluble(>50%) and inorganic element Ca existed in bio-chars mainly in the form of acid-soluble(>14%) and residual(>29%), however, inorganic element Fe existed in bio-chars mainly in the form of residual(>60%).The inorganic elements K?Na?Mg?Al existed in bio-oils produced from liquefaction with water(acetone or ethanol) as liquefaction solvent mainly in the form of water-soluble(>74%), however Ca?Fe existed mainly in the form of oil-soluble organic salts(>70%) and the percentages of which decreased as the liquefaction temperature increased. At the same time, the percentages of oil-soluble organic calcium and oil-soluble organic iron in bio-oils with acetone as liquefaction solvent were higher. In addition, the percentages of insoluble iron in bio-oils with ethanol as liquefaction solvent were higher than those obtained from water(or acetone).