(603c) Membrane Reactor Technology for Aqueous-Phase Hydrogenation of Biomass Derived Intermediates

Realization of a biorefinery, analogous to a petrochemical refinery depends on the efficient conversion of biomass feedstock into a wide variety of chemical intermediates. Having the capability of being integrated in to the existing infrastructure of a petrochemical refinery is one of the most lucrative aspect of a Biorefinery1. However, one of the biggest hurdle is the high oxygen content of biomass and biomass-derived intermediates from conventional hydrocarbons2. Moreover, biomass intermediates are naturally water soluble, which results in high environmental compatibility but it also dramatically impedes the performance of a system with respect to chemical transformations. This difference results in the variation of basic physical properties and therefore the variation in important conversion techniques like hydrogenation. Hydrogenation is an important step in transforming chemical intermediates to products. We are developing chemical conversion technology specifically designed to treat biomass-derived chemicals. Hydrogenation of biomass derived substrates in aqueous phase is a technical challenge due to the slow rate of delivery of hydrogen through the water phase and to the catalyst surface. Also, biomass-derived substrates have the propensity to undergo undesirable side reactions3. We are investigating hydrogenation of Glutamic acid as a model reaction. In order to improve the availability of hydrogen on the catalyst surface, catalytically active membranes are being looked upon. The metal decorated membrane allows for high selectivity towards hydrogen and negligible permeability for Glutamic acid. The hydrogen diffuses from the permeate side of the membrane due to an imposed hydrogen pressure difference. Hydrogen supply rate is controlled by the membrane and imposed pressure difference and essentially is independent of the reaction media. By decoupling hydrogen availability and solubility in the reaction solvent the rate and selectivity of the reaction can be controlled. This study can thereby contribute towards enhancement of biorefinery processing techniques. References: 1. Fernando, S.; Adhikari, S.; Chandrapal, C.; Murali, N., Biorefineries: Current status, challenges, and future direction. Energy & Fuels 2006, 20 (4), 1727-1737. 2. Demirbas, A., Biorefineries: Current activities and future developments. Energy Conversion and Management 2009, 50 (11), 2782-2801. 3. Adkins, H.; Billica, H. R., EFFECT OF RATIO OF CATALYST AND OTHER FACTORS UPON THE RATE OF HYDROGENATION. Journal of the American Chemical Society 1948, 70 (9), 3118-3120.