Design of Catalytic Membrane Reactors for Biomass Hydrolysis and Separation

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PI: Qian, Xianghong and S. Ranil WickramasingheInstitution: University of ArkansasProposal Number: 1264896Title: Design of Catalytic Membrane Reactor for Biomass Hydrolysis and SeparationThe overall objective of this project is to develop a catalytic membrane reactor for biomass conversion that results in high yields of sugar at low cost. Most liquid phase processing technologies for production of biofuels start with monomer sugars (glucose, fructose, xylose, etc.) from biomass fractionation. The current paradigm uses corrosive, dilute sulfuric acid for pretreatment to hydrolyze hemicelluloses. Relatively expensive enzymes are used to break down cellulose. Current technology gives low sugar yields at high cost. The PIs will overcome these problems by designing sulfuric acid and enzyme replacement catalysts that operate at a higher conversion rate than the analogous natural enzymes and that cost far less to produce. The PIs aim to develop reusable, environmentally friendly catalysts for conversion of hemicelluloses and cellulose in one step in an aqueous, mixed water and ionic liquid (IL) solvent. Sugar yields will be improved by immediate separation of hydrolyzed monomer sugars thus minimizing degradation. The appropriate choice of the membrane and its pore size will allow permeation of an aqueous monomeric sugar stream and retention of the IL for reuse.This project is multidisciplinary in nature, encompassing catalyst synthesis via surface modification, product separation and computational chemistry. Low cost conversion of biomass to produce high yields of sugar will be achieved via the following approaches:o Application of combinatorial methods to the computational design of enzyme replacement catalysts for cellulose and hemicellulose hydrolysis to monomer sugars.o Grafting computationally designed nanostructures from porous inorganic membrane surfaces in order to build a catalytic membrane reactor for simultaneous hydrolysis and sugar separation.Intellectual Merit: Solid-acid catalysts made of two neighboring polymeric nanostructures will be designed and synthesized. A polystyrene sulfonic acid (PSSA)-based nanostructure will be immobilized on inorganic membrane surfaces and used to catalyze biomass hydrolysis. A neighboring polymeric ionic liquid (PIL) nanostructure will help solubilize cellulose and enhance the catalytic activity. The solubilized monomer sugars will then be extracted from the reaction media through the pores of the membrane. The acidity and binding affinity of a PSSA polymer nanostructure can be tuned by ring substitution and/or copolymerization. Completion of the research will result in a catalytic membrane reactor for simultaneous hydrolysis of cellulose and hemicellulose that maximizes sugar yields. Advances in materials science will include new surface modification methods for grafting complex customized nanostructures from membrane surfaces.Broader Impacts: Development of biofuels from cellulosic biomass as a replacement for fossil fuels could have important societal impacts: biofuels are renewable and sustainable energy sources; using biofuels can help minimize emissions of greenhouse gases to the environment. The research is multidisciplinary, leading to education and training opportunities for both graduate and undergraduate students. International collaboration with University of Duisburg-Essen in Germany will provide international experiences for the students working on this project. Outreach activities that promote science and engineering to underrepresented minorities are an integral part of the these activities. The research and educational results will be disseminated widely in peer-reviewed journals. This work will result in the training of a new skilled work force in an to meet the challenges in moving from a fossil fuel dominated refinery industry to a future biorefinery industry.