Hydrogen-rich gas production from algae-biomass by low temperature catalytic gasification

• Major pyrolysis of Scenedesmus almeriensis biomass occurs from 200 to 500 °C.
• Water vapour promotes reforming, water gas and WGS reactions improving H2 in gas products.
• Coupled pyrolysis–gasification processes are addressed over Ni based catalysts.
• Gas from pyrolysis and tars are reformed by Ni-catalyst in a second bed upstream.
• Pt–Ni/Al2O3 catalyst allows a hydrogen rich gas with a HHV of 25 MJ Nm−3 at 700 °C.

H2 rich gas produced from Scenedesmus almeriensis biomass residue after lipidic extraction by low temperature catalytic gasification is addressed. The pyrolysis–gasification behavior under different atmospheres (CO2/He, H2O/He and CO2 + H2O/He) were investigated using thermal gravimetric analysis. The conversion of the biomass takes place into three stages, according to its composition and corresponding to: loose of water bonded (30–200 °C), major pyrolysis involving devolatilization (200–500 °C) and decomposition of bio-char produced (500–800 °C). The calculated apparent activation energy for the main pyrolysis stage was 97 kJ mol−1. Ni-based supported alumina catalysts (Ni, Ni–Pt and Ni–Rh) were prepared by impregnation. The catalyst influence on the final gas composition as well as in its HHV determined in mixed CO2 + H2O/He gasification carried out in a double fixed bed reactor configuration with the catalyst located in the second bed upstream. Parallel and secondary reactions as reforming of tar and char together with WGS and Boudouard also take place favoring gas fraction yield with a value close to 0.3 Nm3 of gas per kg of biomass. The catalytic role of Ni–Pt/Al2O3 catalyst in further reforming of the gas resulting from the gasification improves H2 content even at low temperature interval (600–700 °C).

Figure optionsDownload high-quality image (85 K)Download as PowerPoint slide