(193g) Catalytic Conversion of Biomass Into Levulinic Acid, Formic Acid, and Gamma-Valerolactone

The deconstruction of cellulose into glucose is a central focus for the processing of biomass into fuels and chemicals. The challenge in obtaining a high yield of glucose is to effectively balance the aggressive conditions necessary to overcome the chemical resilience of cellulose while limiting the acid catalyzed and thermal degradation reactions of glucose. We have developed a process that converts cellulose into levulinic acid and formic acid which are more stable chemical intermediates that can be further processed to fuels and chemicals.

Similar to traditional biomass processing approaches, our process utilizes a dilute mineral acid solution to catalyze the hydrolysis of cellulose into glucose. Instead of maximizing the glucose yield, the mineral acid subsequently catalyzes the successive dehydration of glucose to form 5-hydroxymethyl furfural and eventually levulinic acid and formic acid. It has been determined that under the processing conditions used the rate of levulinic acid and formic acid degradation is negligible with respect to the rate of production of these species.

Levulinic acid can be transformed into γ-valerolactone (GVL) through the addition of a heterogeneous catalyst under reducing conditions. Formic acid is degraded over the heterogenous catalyst to produce carbon dioxide and hydrogen. The hydrogen produced in situ is then utilized in the reduction of levulinic acid into GVL over the same heterogeneous catalyst. A kinetic study has been performed for the conversion of levulinic acid to GVL under reaction conditions resulting from to production of levulinic acid from cellulose (i.e., mineral acid, insoluble humins). A kinetic model has been developed to describe the effects of formic acid and mineral acid on the conversion of levulinic acid to GVL.