Dr. Mingxin Guo
Professor, Environmental Soil Chemistry, Delaware State University, United States.

Speech title: Upgrading Organic Residues-derived Pyrolysis Bio-oil into a Quality Liquid Biofuel

Abstract: Pyrolysis of biomass results in three products: biochar, bio-oil, and syngas. Bio-oil, in particular, is a flowing liquid of various low-molecular weight organic molecules and can be utilized as an alternative to liquid fossil fuels. Crude pyrolysis bio-oil, however, contains significant contents of water, organic acids, and char particulates and therefore, is unstable, corrosive, and difficult to ignite. Moderate transformation and upgrading is necessary before the product can be used as a quality fuel. In this study, simple, practical, and effective bio-oil upgrading techniques consisting of phase separation, esterification, and biodiesel blending were explored. Bio-oils from slow pyrolysis of corn stover, poultry litter, and forest debris were first separated into two layers upon addition of NaCl solids at 5 wt%. The bottom dark layer was transformed into a stable, homogenous, ignitable mixture by blending it with biodiesel in the presence of 30wt% butanol. The top light brown layer was co-distilled with 25wt% butanol to reduced its water content from ~65% to <10wt% and further blended with biodiesel to form a usable fuel. The upgrading techniques improved the heating value of pyrolysis bio-oil by 20–30%. The upgraded bio-oil met the ASTM D7544 quality standards and was utilizable as a heating fuel for greenhouses and residential buildings. A brief economic analysis was conducted and the cost of upgrading was about $1.0/gal, which is much cheaper compared to commercial heating fuel ($4.036/gal). The developed bio-oil upgrading techniques are expected to promote on-farm production and utilization of biochar and bio-oil from agricultural byproducts.