(434c) Characterization of Nickel-Olivine Materials as Tar Cracking Catalysts in Biomass Gasification Applications
The development of attrition resistant catalysts is necessary for hydrogen production and gas clean up in gasification processes. Current dolomite catalysts reform tar effectively at the operating conditions normally used in gasification processes (~850°C), but attrition caused by the fluidized bed leads to small particles that are not retained in the reactor. Although it has lower tar reforming activity than dolomite, olivine, an erosion resistant mineral, has potential as a support material in highly active reforming catalysts.
The present work focuses on nickel-olivine catalysts prepared by a high-energy glass melting procedure. The effects of preparation conditions, nickel precursor, and source of the olivine mineral on tar reforming activity are discussed. Tar reforming activity measurements are made by using naphthalene as a model feed molecule in both inert and synthetic syngas (30% N2, 20% H2, 10% CO, 15% CO2, 5% CH4, and 20% H2O) conditions between 750°C and 900°C. Steam reforming activity is also measured by temperature-programmed reactions using lower hydrocarbons.
A thorough catalyst characterization is performed to understand both the influence of the preparation variables and time-on-stream factors on the reforming activity and to determine the nature of the active surface reaction sites. Evidence is provided by techniques such as BET surface area measurements, temperature-programmed reduction/oxidation/desorption studies, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and vibrational spectroscopy.