A promising method for producing hydrogen involves the gasification of biomass with steam. To enhance the concentration of Hâ‚‚ in the ensuing mixture of combustible gases, a carbon dioxide sorbent can be used in situ; calcium oxide is commonly used. A research team from the Laboratory for Sustainable Technology, at the University of Sydney’s School of Chemical and Biomolecular Engineering (Australia; edlinks.chemengonline.com/6518-539), has developed CaO sorbent specifically tailored for biomass gasification. According to team member Andrew Harris, the team has demonstrated a biomass-to-Hâ‚‚ conversion of 86% using the tailored CaO sorbent, compared to a 68% conversion achieved using a commercial CaO sorbent.
Harris believes his team’s work investigates, for the first time, the synthesis of a tailored CaO sorbent designed for the in situ capture of COâ‚‚ during gasification. The team has developed a precipitation technique that uses a slurry bubble column to make CaCO3 with tailored morphological properties. This follows previous work by several workers who used a precipitation technique to synthesize CaCO3 for the separation of SOâ‚‚ and COâ‚‚ from fluegas. A carefully-controlled calcination step converts the CaCO3 into CaO while retaining the optimized pore structure.
The sorbent is being tested in a gasifier that processes â‚‚ kg/h of biomass. Plans are underway to build a 25-kg/h pilot plant that will be coupled to a commercial fuel cell to demonstrate, for the first time, electricity generation with COâ‚‚ capture from biomass.