Tunable solvents for fine chemicals from the biorefinery

Abstract

Making biorefineries economically and environmentally sustainable is the biggest barrier to the mass commercialization of biofuels in this country. One way to add economic value to the biofuel process is to isolate and extract fine chemicals from waste biomass such as lignin, extractives, and unreacted cellulose and hemicellulose. In this paper we demonstrate a technique for extracting high-value added chemicals such as vanillin, syringaldehyde, and syringol from lignin using a novel CO₂-expanded organic solvent (gas-expanded liquid). This method incorporates many principles of green chemistry while offering several economical advantages to the biorefinery: low operating costs, easy recycling of organic solvents, use of a renewable feedstock, and a way to produce chemicals without wasteful synthesis. Furthermore, this technique demonstrated the ability to produce high-value chemicals ($5–25 lb⁻¹) from a waste source that is presently being burned for a fuel value of 2–3 cents lb⁻¹. We believe the process presented in this paper will spark interest in developing other sustainable techniques to extract fine chemicals from biorefinery waste.