(510g) Membrane Reactor Technology for Aqueous-Phase Hydrogenation of Glutamic Acid

Realization of a biorefinery, analogous to a petrochemical refinery depends on the efficient conversion of biomass feedstock into a wide variety of chemical intermediates. One of the biggest hurdle is the high oxygen content of biomass and biomass-derived intermediates from conventional hydrocarbons. 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 chemical composition and therefore the variation in important conversion techniques like hydrogenation. Hydrogenation is an important step in transforming chemical intermediates to products. 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 reactions. 

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 Ru metal decorated polymeric membrane allows for high selectivity towards hydrogen and negligible permeability for Glutamic acid.

Results from the initial experiments demonstrate the effect of processing conditions and performance compared to the conventional (high pressure, stirred tank) systems. Using the membrane reactor technology described here, hydrogenation of Glutamic Acid was successfully performed with very high conversion at pressure of less than 40 psig compared to the 2000 psig used in the conventional system.  Advantages of this proposed technology include a reduction in the capital cost resulting from mild operating conditions; an increase if ease of use realized by the elimination of high pressure hydrogen, which presents a significant safety hazard; and the potential to influence the product spectrum through process conditions.