2025 AIChE Annual Meeting

(104b) Effect of Supercritical Water Gasification Catalyst on Reaction Mechanism

Authors

Kosaku Yamada - Presenter, Hiroshima Univ.
Yukihiko Matsumura, Hiroshima University at Japan
Raito Arakawa, Hiroshima Univ.
Supercritical water gasification is a promising technology to gasify wet biomass for energy recovery. It has been studied by many researchers and its commercialization is sought. However, due to the high price for the process, it is not easy to commercialize this process. This high price is due to the fact that for complete gasification, high temperature or effective catalyst is needed. When high temperature is employed, the reactor has to endure high pressure under high reaction temperature, and the cost of the reactor is high. Catalysts are helpful to reduce this cost by moderating the severe reaction conditions. So far, mainly carbonaceous catalyst, metal catalyst, and alkali catalyst has been employed. However, due to the high temperature and pressure in the reactor of supercritical water gasification, the reaction mechanism has not been well elucidated. When activated carbon catalyst is employed, adsorption of the product organics on the catalyst is also a problem. With proper reaction modeling and supportive experiment, reactor design and determination of the conditions can be made more effectively. The purpose of this study was to analyze product organics produced with catalyst in supercritical water gasification, and to elucidate the effect of catalyst. For the case of activated carbon catalyst, adsorption characteristics of product organics was determined and separation of the effects of reaction and adsorption was made. The result indicated that only 5-hydroxymethylfurfural and furfural are adsorbed onto activated carbon. It had been assumed that activated carbon suppresses production of these furans, but apparently, it was just adsorption. The effect of activated carbon was found to enhance formaldehyde production and relative suppression of methanol production. The experimental results for a metal catalyst are also discussed.