Improving quality and stability of biofuels via feedstock pretreatment and inline and secondary processing

Abstract

Renewable fuels will be required to meet the demand for transportation fuel in the near future. Deficiencies in biofuels including inadequate feedstock availability, low yield upon conversion, and poor fuel quality and stability have, as yet, limited widespread usage. The work described herein explores a variety of methods to improve the yield, quality, and stability of biomass-derived fuels. Bioconversion techniques attempted here included feedstock pretreatment by torrefaction, inline processing by catalytic esterification, and secondary processing by catalytic cracking in addition to primary processing by pyrolysis. Bioconversion techniques were undertaken in various combinations for both high free fatty acid and lignocellulosic material-derived feedstocks. Results have shown that vegetable oils can be treated effectively to generate gasoline, aromatic hydrocarbons (e.g. BTEX) in particular, at yields greater than 40 % (v/v). Also, results revealed that both gasoline and diesel hydrocarbons including aromatics and aliphatics were generated from the catalytic cracking of pyrolysis oils derived from lignocellulosic feedstocks including pine wood and peanut hulls. Catalytic esterification of bio-oil vapor resulted in the formation of esters and acetals. As a result of pretreatment and inline and secondary processing, significant improvements were seen in fuel quality and storage stability of biofuel products.