Catalytically Responsive Membranes for Simultaneous Biomass Hydrolysis and Separation

Reaction and product separation steps may be combined using catalytically responsive membranes resulting in significant process intensification.  Here we focus on biomass hydrolysis for production of biofuels.  Currently, dilute sulfuric acid pretreatment is one of the leading technologies to hydrolyze hemicelluloses, relocate lignin and expose cellulose during biochemical conversion of biomass to monomer sugars. A cocktail of cellulose enzymes is used to break down cellulose. The major problems associated with this technology are the slow and incomplete hydrolysis of cellulose and the degradation of monomer sugars during pretreatment. Further, the cost of the enzymes has been an inhibitory factor for the commercialization of biofuels.

Here ceramic membranes have been functionalized by growing poly(styrene sulfonic acid) (PSSA) chains as well as polymeric ionic liquid (PIL) chains from the surface of ceramic membranes.  A UV initiator based on a benzoin ether derivative and 2-bromobutyryl bromide (ATRP initiator) were immobilized on the ceramic membrane surface.  Next ATRP of sodium 4-styrenesulfonate was conducted followed by UV initiated free radical polymerization of 1-vinylimidazole(VI).  The density of the PSSA and PIL chains were varied by varying the incubation times of the two different initiators.  Modified membranes were characterized using X-ray Photoelectron Spectroscopy, Infrared Spectroscopy and Scanning Electron Microscopy.

A membrane reactor was designed and tested using feed streams consisting of cellulose in water and water/ionic liquid mixtures.  Glucose as well as reduced sugars were collected in the permeate.  Our results indicate the feasibility of hydrolyzing cellulose and simultaneously removing hydrolyzed sugars.