Novel polymeric solid acid catalysts for cellulose hydrolysis
Novel solid polymeric catalysts consisting of polymer chains have been synthesized to facilitate cellulose dissolution and catalyze its hydrolysis. Poly(styrene sulfonic acid) (PSSA) polymer chains have been grown from the substrate surface and used to catalyze biomass hydrolysis. Neighboring poly(vinyl imidazolium chloride) ionic liquid (PIL) polymer chains, also grown from the substrate surface, help solubilize lignocellulosic biomass and enhance the catalytic activity of the PSSA chains. The PSSA chains were synthesized via surface initiated atom-transfer radical polymerization (ATRP) whereas the adjacent PIL chains were synthesized via UV-initiated free radical polymerization. These novel polymeric solid acid catalysts demonstrate over 97% and 32% total reducing sugar (TRS) yields from cellulose hydrolysis in [EMIM]Cl and aqueous solutions respectively. The dual ATRP and UV-initiated polymerization schemes allow independent variation of the relative ratio of the two nanostructures as well as the chain length and density. This permits optimization of the catalytic activity for cellulose hydrolysis reaction. These catalysts are stable and maintain high catalytic activity after repeated runs.