Production of Hydrogen and/or Syngas (H₂ + CO) via Steam Gasification of Biomass-Derived Chars

Abstract

Steam gasification of two biomass-derived chars was studied at 700, 750, and 800 °C in a fixed bed microreactor at different steam flow rates in the range of 1.25 to 10 g/h/g of char. The chars used in the present study were (i) bagasse charobtained from Natural Resources Canada, CANMET Energy Technology, Ontario (produced by Dynamotive Technologies Corp., Vancouver, BC), and (ii) commercial charobtained from ENSYN Technologies Inc., Ontario (produced during the fast pyrolysis of biomass using their RTI process). Both chars were highly reactive, particularly at 800 °C with steam flow rate of 5 and 10 g/h/g of char. In the case of bagasse char, maximum conversion of 81% was achieved at 800 °C with a steam flow rate of 10 g/h/g of char, whereas maximum conversion of 69% for commercial char was obtained at 800 °C with steam flow rates of 5 and 10 g/h/g of char. The product gas obtained was mainly a mixture of H2, CO, CO2, and CH4 with a high H2/CO molar ratio (about 4:7 for bagasse char and 9:15 for commercial char) at a temperature of 800 °C and a steam flow rate of about 10 g/h/g of char. Under the present reaction conditions, synthesis gas (H2 + CO) produced by steam gasification of bagasse char and commercial char was in the range of 80−88 mol % and 77−84 mol %, respectively. The heating value of the product gas was in the range of 270−290 Btu/scf for bagasse char and 250−280 Btu/scf for commercial char. The results suggest that there is a strong potential for producing hydrogen and syngas from biomass-derived chars by a simple steam gasification process.