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SULFUR TOLERANT CATALYSTS FOR BIOMASS TAR REMOVAL - PHASE I
Description:
In this Small Business Innovation Research (SBIR) project, NexTech Materials proposes a catalytic reforming approach to remove waste tar from gasified biomass on nickel-based catalysts. Biomass gasification is a potential renewable route to producing electricity, liquid fuels and value-added chemicals. At high temperatures, carbonaceous biomass reacts with air, oxygen and /or steam to produce a gaseous product containing mostly H2, CO, CO2, H2O2 and CH4. Subsequently the gasified product gas is further processed into energy (via gas turbines or fuel cells), hydrogen (via additional catalytic reaction and purification steps) or into liquid fuels of chemical (via Fischer-Tropsch processes). However, the mixture of condensable hydrocarbons (e.g., polycyclic aromatic hydrocarbons) can foul turbines, fuel cells and other downstream processing and utilization equipment. Thus it needs to be removed after the gasification process in order to protect down-stream equipment. A major challenge to utilization of biomass gasification technology is cost-effective and efficient removal of tar from the product stream. An established technology that is used today is liquid scrubbing. This approach needs to cool gasification gas from about 900°C to near ambient temperature, reducing energy efficiency since most downstream processes occur at higher temperatures. Further, the generated liquid waste still needs to be treated in an environmentally responsible manner later. In comparison, the proposed catalytic reforming method will not only enhance overall energy efficiency and eliminate the process for the liquid waste disposal, but also convert tar, methane and light hydrocarbons to useful syngas, thus increasing the fuel value. On the nickel based catalysts, hydrocarbons can react with steam and CO2 to produce CO and H2. The catalysts have shown good activity in tar reforming and 900°C and are tolerant to H2S and NH3, two impurities in the biomass gasification product. The lower temperature activity will be improved by adding a small amount of promoters due to the enhancement of the catalyst reducibility. This sulfur tolerant catalyst will enable efficient use of biomass to produce power, liquid fuels and valuable chemicals.