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Reactivity of Catalyst-Suspended Slurry in Supercritical Water

Yukihiko Matsumura1, Takuya Yoshida1, Shoutarou Hara2, Tomoaki Minowa3, Yoji Noda4, and Yoshihisa Shimizu5. (1) Hiroshima University, 1-4-1 Kagamiyama, Higashi-hiroshima-shi, Hiroshima, 739-8527, Japan, (2) Department of Mechanical System Engineering, Hiroshima University, 1-4-1 Kagamiayama, Higashi-hiroshima, Hiroshima, Japan, (3) Biomass Technology Research Center, National institute of Advanced Industrial Science and Technology (AIST), 2-2-2 Hiro-Suehiro, Kure, 737-0197, Japan, (4) Toyo Koatsu Co., Ltd., Hiroshima, Japan, (5) The Chugoku Electric Power Co., Inc., Hiroshima, Japan

Supercritical water gasification is a technology to gasify wet biomass effectively by applying high pressure and temperature with a short residence time in the reactor. To facilitate the gasification, catalyst particles have been packed in the reactor. However, gasification operation often results in production of tarry materials, and thus deactivation of the catalyst as well as plugging of the reactor was a big problem in operation. In this study, a novel supercritical water gasification where catalyst was suspended in the feedstock so that no packed-bed reactor is needed is proposed, and fundamental reaction characteristics are reported. Chicken manure was employed as a feedstock, and after pulverization, hydrothermal pretreatment, and sieving, activated carbon particles were added. The resulting slurry was placed in a high-pressure feeding piston equipment, and continuously fed to the laboratory scale reactor. After passing through the reactor, product gas and catalyst-suspended liquid phase effluent were cooled down to the room temperature. Then solid particles were removed by sedimentation, and remaining liquid and solid were depressurized and recovered. Reaction temperature ranged from 600 to 700oC, and reaction pressure was kept at 25 MPa. Chicken manure was successfully gasified in the reactor, and activated carbon catalyst was successfully recovered in the sedimentation vessel. It was observed that activated carbon also adsorbed unconverted organic compounds.