Supercritical Water Process converts Biomass to Sugars Chemical Engineering

Sugar is a critical feedstock for many emerging bio-based-chemical and biofuel processes, but harvesting sugar from lowvalue, nonfood biomass cost-effectively and at large scale remains a challenge. Renmatix Inc. (King of Prussia, Pa.; www.renmatix.com) has developed a process that uses water above its critical temperature and pressure to hydrolyze a range of biomass materials to make C5 and C6 sugars. Unveiled at an event last month, the Renmatix process, known as Plantrose, offers what may be the lowest-cost approach to supplying sugar for the growing bio-chemical and renewablefuel markets.

The company currently converts three dry-tons per day of waste hardwood chips into sugar at a demonstration facility in Kennesaw, Ga. Renmatix CEO Mike Hamilton says the company will announce next year the location of a planned commercialscale facility that will be capable of producing 100,000 ton/yr of sugar. The first plant may be co-located with a bio-based chemicals maker that can use the sugar from Renmatix’s process.

The Plantrose process is built around a supercritical hydrolysis platform, which capitalizes on the ability of supercritical water (SCW) to depolymerize cellulose, where water below the critical point cannot. Another unique aspect of the process is its two-step method that first separates the easier-tobreakdown hemicellulose before subjecting the tougher cellulose to SCW conditions that would destroy the C5 sugar. Plantrose begins with a slurry of waste woodchips that enters a fractionation reactor, where hemicellulose is solubilized into a C5 sugar stream. The remaining solids (cellulose and lignin) are then subjected to precisely controlled conditions that bring water above its critical point to generate glucose. The lignin is separated and collected as a solid.

The speed of the SCW hydrolysis (seconds) contributes to lower capital expense, says Hamilton, adding that the Plantrose process requires no significant consumable materials and utilizes heat from burning the solid lignin, so production costs are low.

Ref: CHEMICAL ENGINEERING - WWW.CHE.COM - NOVEMBER 2011