It is known that the reactivity of coal char was improved owing to the catalytic effect of the alkaline minerals in biomass. The gasification of coal and the co-gasification of biomass and coal were performed on a fixed bed gasifier with four gasifying agents, nitrogen, carbon dioxide, steam, steam and oxygen. The isothermal condition is 800°C and the time is 30 min. Alkali contents of coal char were measured by ICP-MS. The effects of reaction atmosphere on alkali metal migration were investigated. Results show that the amount of alkali metal migrated to the coal char under the carbon dioxide, steam, steam and oxygen atmospheres is significantly higher than that under the nitrogen atmosphere and the migration of alkali metals in the three atmospheres is not very different. The activity of coal char under steam and oxygen atmosphere is significantly higher than that of the other three atmospheres. Only part of the alkali metal migrated into the coal char has catalytic activity. The oxygen content in the coal char has a good positive correlation with the alkali metal content in the coal chars under carbon dioxide, steam, steam and oxygen atmospheres. The experimental results indicates that the migration of the alkali metal has little relationship with the specific surface area of the coal char and the specific surface area of the coal char cannot significantly improve the catalytic activity of the coal char. The increase of oxygen content in coal char is beneficial to the fixation of alkali metal and improving the catalytic activity of the alkali metal. In this study, combining the experimental results with SEM analysis, the fixed form of alkali metal in coal char is probably the C-O-M morphology.

Gas agents effect of co-gasification of coal and biomass on alkali metal migration and its catalytic performance

253rd National Meeting (2017)

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