Conversion of Lignin to Hydrocarbon Fuels Via Catalytic Depolymerization and Hydrogenation

Three different solvent systems (sodium hydroxide solution, ethanol aqueous solution and aqueous solution of phosphoric acid) were chosen to study the conversion of lignin to hydrocarbons via catalytic depolymerization and hydrogenation. A two-step method, selective depolymerization of lignin to liquid compounds rich in phenolics followed by hydrogenation of the obtained liquid, was developed. It was found that sodium hydroxide solution showed the best performance among the three, as the yield of phenolic compounds could reach 60%, with a selectivity of 85% when used for lignin degradation. What’s more, the selectivity for hydrocarbons could reach 97% when the derived phenolic compounds were hydrogenated. The preliminary mechanism study using model compounds indicated that the conversion of lignin to hydrocarbons is a multi-step process consisting of alkaline hydrolysis, demethylation, demethoxylation and transalkylation.