Biomass ash,rich in alkali and alkaline earth metals(AAEM),can be served as a natural catalyst in coal catalytic gasification.The promoting effect of biomass ash on coal gasification is a fundamental reason for the synergistic effect during co-gasification of biomass and coal.However,the AAEM in biomass ash may undergo deactivation during gasification,leading to the loss of catalytic activity.The effects of factors such as biomass ash type,content and temperature on coal char gasification through fixed-bed pyrolysis and gasification experiments were analyzed,combined with the analysis of XRD,Raman,XRF,and BET.The results indicate that the catalytic effect of biomass ash is related to the content and existing form of AAEM.The gasification reactivity of coal char increases with the increasing addi-tion of wheat straw ash.However,when the addition of wheat straw ash reaches 40％,the reactivity of the coal char tends to change smoothly.Wheat straw ash has an inhibitory effect on the gasification of coal char in the early stage of gasification reaction.As the car-bon conversion increases,the catalytic effect of wheat straw ash decreases with the increasing temperature at the same conversion level.In order to inhibit the deactivation of potassium in wheat straw ash,eggshell was used as an additive to investigate the effects of mixing wheat straw ash with eggshell on the gasification of coal char.The results indicate that the catalytic effect of wheat straw ash on the gasification of coal char can be further enhanced by adding 25％wheat straw ash and 5％eggshell.The addition of wheat straw ash results in a large specific surface area,an enriched pore structure,a more disordered carbon structure,a decrease in the gasification reaction activation en-ergy and an increase in the gasification rate of the coal char.Random pore model is the most appropriate model to simulate the gasification behavior of coal char and the coal char with wheat straw ash.The findings provide a reference for the application of biomass ash in catalytic coal gasification.
biomass ashcatalytic coal gasificationalkali metal deactivationcalcium-based additivegasification reaction kinetics
维普
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