15-03: Novel Catalytic Processing of Lignin to Aromatic Hydrocarbons

By producing multiple products, a biorefinery can utilize the benefits of various biomass components and their intermediates to maximize the value derived from biomass feedstocks. Thus, developing specialty and commodity products from biomass derived-lignin has been a major industrial and scientific endeavor for several decades. However, deconstruction of the complex lignin polymeric framework into low molecular weight reactive moities amenable for subsequent removal of oxygen to produce aromatic hydrocarbons has proven to be challenging. A novel catalytic technology that can both selectively depolymerize the lignin polymeric framework and remove oxygen via hydrodeoxygenation (HDO) processes has been developed. We have successfully demonstrated 35%~60% conversion yield of lignin with 25%~40% product selectivity for aromatic hydrocarbons under various HDO conditions in the presence of 5% Ru/Al₂O₃(or C)-Zeolyst (e.g.,NH4+ Z-Y 57277-14-1) catalyst matrix. The overall strategies for producing aromatic hydrocarbons from lignin include: (i) depolymerization of the complex lignin structure to highly reactive low molecular weight intermediates via selective C–O–C and C–C bond cleavages; (ii) substantial reduction of oxygen content from the lignin intermediates (LI) via catalytic HDO reactions for conversion of phenolic like components to aromatic hydrocarbons; and (iii) optimizing the catalyst systems for high HDO yields for production of aromatic hydrocarbons. The reaction chemistry and kinetics of lignin depolymerization and HDO conversion process will be presented.