(737a) Catalytic Performance of Char for Reduction of Tars in Biomass Gasification

Biomass has the potential for meeting a significant portion of the demand for energy and transportation fuels in the near future.  Gasification is a thermochemical conversion method that creates synthesis gas from biomass, which enables the production of a wide variety of products such as fuels, electricity, or chemicals. Two of the main by-products of gasification are tar anc ash or char.  Tar can be converted to synthesis gas via catalytic steam reforming, but the tars cause rapid catalyst deactivation. Char has been shown to have catalytic activity for tar decomposition. However, char properties vary based on gasification conditions, which will impact its catalytic performance.  In our experiments, poplar wood was gasified in a fluidized bed reactor under 10% CO₂/90% N₂ and 90% H₂O/10% N₂ at temperatures ranging from 550-920^oC.  Data is presented that demonstrates the char’s catalytic performance for decomposition of hydrocarbons such as methane and propane.  The surface area of the char ranged from 400-680 m²g^-1, which is significantly higher than typical catalyst carriers.  For example, the surface area of gamma alumina is around 150m²g^-1. The catalytic performance of the char was related to the surface area, with higher surface area giving higher catalytic performance.  The presence of iron was identified in the char and carbon deposition was observed on the iron, which suggests it may be a catalytic site.  However, the performance of ash is lower than that of char and therefore it is likely that the metal-carbon interactions are important to the catalytic performance of the char. This presentation will discuss the catalytic performance of the char as well as the relevant properties of the char and how they impact its performance.