Fractional condensation and aging of pyrolysis oil from cotton stalk

Abstract

The current study is to investigate a multi-condenser system for separating pyrolytic vapors as a promoting method to produce bio-oils that are more impervious to aging. Bio-oil vapors produced by fast pyrolysis of cotton stalk in a fluidized bed reactor at a temperature of 500 °C and were divided by a fractional condensation system into four fractions. The results showed that the stability of the fractional bio-oil was improved because most of the reactive aliphatic compounds with small molecules involving water rich organic acids, aldehydes and ketones were effectively separated from the other components. It was found out that the stability of bio-oil was affected by the active chemicals derived from fast pyrolysis as well as the aqueous acidic condition of bio-oils because most polymerization, condensation and electrophilic addition substitution reactions need the presence of H+ to be the catalyst. The observation pointed out that the suspended solid particles (SS) in bio-oils can be suppressed by separating conventional bio-oils into different stages by means of concentrating the initial SS in a certain fraction.