The Effects of Integrated Chemical Catalysis and Reductive Pretreatment on Hydrothermal Liquefaction Derived Bio-oil Yield, Composition, and Stability

Abstract

Bio-oil is a viscous mixture of aldehydes, ketones, etc. It can be used for various applications such as chemicals or fuels. However, due to its acidic nature, bio-oil is unstable. Integrated chemical catalysis (ICC) and reductive pretreatment (RP) hydrothermal liquefaction (HTL) of the biomass feedstock (corn stover and hybrid poplar) were performed in an effort to stabilize the resultant bio-oil. In ICC trials, acidic, basic, and reductive solutions were added to the HTL chamber. RP trials were completed separately. Yield, composition, and stability analysis were conducted using fractionation and GC-MS techniques. Phase distribution was relatively unaffected by varying ICC treatments. Acidic ICC increased furan derivative relative abundance in the bio-oil, while alkaline ICC and RPs decreased furan content. RPs increased double bonded γ-carbon compounds such as eugenol. RPs and alkaline ICC trials increased bio-oil pH and subsequently bio-oil stability, whereas acidic ICC lowered bio-oil pH and destabilized the product.