Energy & Fuels, Vol.30, No.5, 4009-4016, 2016
Studies of Distribution Characteristics of Inorganic Elements during the Liquefaction Process of Cornstalk
Liquefaction of cornstalk for producing bio-oil was conducted with different solvents (water, ethanol, and acetone) at temperatures of 280, 320, and 360 degrees C. The distribution characteristics of the 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. The inorganic elements distributed mainly into biochars (>60.0 wt %) with acetone and ethanol as solvent, with less than 26 wt % into the bio-oils; however, K and Na distributed mainly into aqueous phases with water as solvent, and Ca, Al, and Fe distributed mainly into biochars, with less than 31 wt % into the bio-oils. Increasing liquefaction temperature (320 to 360 degrees C) reduced the contents 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 and ethanol; however, the concentrations of Ca and Fe in bio-oil obtained from acetone were higher than those obtained from water and ethanol. It was suggested that the bio-oil should be pretreated before utilization.