(344d) Catalytic Membranes for Biomass Hydrolysis and Dehydration

Authors: 
Wickramasinghe, S. R., University of Arkansas
Qian, X., University of Arkansas
Biofuels and chemicals derived from lignocellulosic biomass are leading renewable energy candidates to replace fossil-based transportation fuels and chemicals. However, the economic viability of biproducts is significantly hindered by manufacturing costs. Our paradigm changing catalyst and membrane reactor is not only cheaper than cellulase enzyme (currently the workhorse for cellulose hydrolysis), but also, we combine three unit operations: thermochemical pretreatment, detoxification and enzymatic hydrolysis into a single unit operation.

A catalytic membrane reactor has been developed to simultaneously catalyze the hydrolysis of cellulosic biomass and separate the monomer sugars with improved sugar yields and efficiency. An enzyme mimic catalyst has been synthesized by growing poly(styrene sulfonic acid) (PSSA) chains as well as poly (vinyl imidazolium chloride) ionic liquid (PIL) chains from the surface of ceramic membranes. These polymeric solid acid catalysts are able to facilitate cellulose dissolution and catalyze its hydrolysis reaction. PSSA catalyzes biomass hydrolysis whereas PIL helps solubilize the biomass and enhance the catalytic activity. Our solid acid catalysts demonstrate over 97% and 32% TRS yields from crystalline α-cellulose hydrolysis in ionic liquid [EMIM]Cl and aqueous solutions respectively. Moreover, these catalysts are able to convert cellulose directly to 5-hydroxymethylfurfural (HMF) with over 60% yield. These catalysts are stable and maintain high catalytic activity after repeated runs.

Further we have shown that our solid acid catalyst can catalyze the production of sugars and platform chemicals (glucose, xylose, hydroxymethylfurfural (HMF) and levulinic acid) directly from the lignocellulosic biomass depending on the reaction temperature and solvent. Our catalyst is reusable, environmentally friendly and can be easily regenerated. Its catalytic activity can be easily tuned by altering the polymer chain length, chain density and the relative ratio of the two nanostructures. Moreover, it can be potentially used for many other acid catalyzed reactions.