Catalytic conversion of biomass to value-added chemicals provides renewable alternatives to a wide range of products of interest in our everyday life, ranging from monomers, bio-compatible plastics to environmentally friendly detergent cleaners. These conversion processes often involve complex multistep reactions such as hydrogenation/hydrogenolysis, oxidation, dehydrogenation, dehydration, condensation and amination. The challenge is to develop active, selective and stable catalysts to meet the economic and environmental compatibility. This lecture will present an overview of recent development in biomass conversion technologies with specific reference to hydrodeoxygenation (HDO) and oxidation of sugars and polyols. Distinguishing features of biomass feedstocks and their conversion processes are: (a) they are oxygen rich in contrast to petroleum feedstocks consisting of hydrocarbons, (b) thermally unstable at higher temperatures demanding liquid phase processing and (c) overall selectivity depends on competing reactions requiring control of C-O, C-C, C-H and C-N bond cleavage/coupling reactions. The catalysts used, reaction pathways and kinetic modeling will be discussed with specific examples on (a) HDO of polyols to glycols and value added products and (b) oxidation of sugars and polyols to mono and dicarboxylic acids. While HDO is a known example of an alternative route for 1,2 propanediol, the selectivity varies with catalyst, supports and reaction conditions. Major disadvantage is the large consumption of expensive hydrogen and significant yield loss in deoxygenation. In this context, a new concept of tandem dehydrogenation/reforming coupled with HDO to achieve high selectivity of value added products will be discussed. In contrast to HDO, oxidation of sugars and polyols to carboxylic acid derivatives has the advantage that the rich oxygen value in the feedstocks is retained. The role of novel bimetallic catalysts for activity and selectivity improvement will be discussed along with detailed surface characterization and kinetic studies.

Design of bimetallic nano-catalysts for biomass conversion to chemicals

251st National Meeting (2016)

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