Catalysis in biomass gasification

Abstract

Carbon deposition Catalyst formu-Several types of carbon deposition on nickel catalysts are known to occur in steam-reforming of hydrocarbons. The mechanisms for formation of polymer, whisker, and pyrolytic carbons are discussed. These studies have revealed promising approaches to the development of effective catalyst systems for gasification of biomass. The influence of process variables, such as char residence time, gas velocity, and biomass particle size, has been shown to be important to the catalytic process design.

Bench-scale studies on gasification of biomass in the presence of catalysts

“…Alkali carbonate catalysts using biomass feedstocks are known to have a significant effect on both pyrolysis and char gasification (Baker and Mudge 1984a). They have previously been tested extensively in the laboratory gasifier, and a limited number of tests have been completed in the PRU.…”

“…They have previously been tested extensively in the laboratory gasifier, and a limited number of tests have been completed in the PRU. Data on _the kinetics of the steam-char reaction were obtained on the laboratory scale (Mudge et al 1981;Baker and Mudge 1984a). The objective of the bench-scale tests was to confirm laboratory-scale results on a larger scale.…”

“…Catalysts may be used in biomass conversion processes in a variety of applications to enhance conversion efficiency and environmental acceptability. Gasification of biomass in the presence of catalysts has been studied in the 1 aboratory and the process research unit ( PRU) at the Pacific Northwest Laboratory (PNL)(a) since 1978 (Mudge et al 1981;Mudge et al 1983;Baker and Mudge 1984a) under a contract with the Biomass Thermochemical Conversion Program of the U.S. Department of Energy (DOE). These studies identified secondary (supported metal) and primary (alkali carbonate) catalysts that were effective for conversion of biomass to specific gas products.…”

“…The question of whether there is a net buildup of carbon and subsequent catalyst deactivation depends on the relative rates of the carbon-forming and carbonremoving reactions. In the closed system employed for the bench-scale tests, the primary carbon-forming reactions are thermal cracking of tars and olefin polymerization (Baker and Mudge 1984a): tars + coke + light hydrocarbons + gases CnH 2 n + polymers + coke The main carbon-removal reaction is the water-gas reaction:…”

Catalytic activities of nickel, dolomite, and olivine for tar removal and H2-enriched gas production in biomass gasification process

“…Nickel-based catalysts, on the other hand, almost completely remove tar. 41,99,101,117,123–128 Nickel-based catalysts are not only active for tar decomposition, but these are also very effective in producing high yields of synthesis gas, 129–133 lead to increase in H 2 and CO content in the gasified product, 134–137 and very operative for ammonia (NH 3 ) removal. 117,128,138–140 Thus, it is possible to reduce NOx emission during biomass gasification.…”