脱灰生物质焦的催化气化反应及动力学

Catalytic gasification reaction and kinetics of deashing biomass char

利用扫描电镜–能谱仪及热重分析仪研究了添加钾盐催化剂的脱灰生物质焦的物理结构、化学成分及其与CO2的气化反应,并分别采用均相模型和收缩未反应核模型对实验数据进行处理,得到动力学参数.研究发现钾盐对脱灰生物质焦–CO2气化反应有明显催化作用,可提高整体反应速率,并减少反应时间.随着钾盐的增加(质量分数在0%～4%的范围内),附着在生物质焦表面的富钾催化点增多,催化作用逐渐增大,反应的活化能逐渐降低.由于(脱灰)生物质焦的灰分含量很低,与未反应核模型相比,均相模型更适合于描述生物质焦–CO2的气化反应过程.

The physical structure and chemical composition of deashing biomass char coated with potash, as well as its gasification reaction with CO2 were investigated by scmming electron microscopy （SEM） equipped with energy dispersive X-ray spectrometry （EDS） and thermal gravimetry. Experimental data were processed with both the homogeneous model and the shrinking unreacted-core model, and kinetic parameters were obtained for the gasification reaction. It is found that there is an obvious catalytic effect of potash o：a the gasification reaction. This catalysis improves the overall reaction rate and shortens the reaction time. As the potash content increases from 0% to 4%, more adhering catalytic points, rich in kalium, can be detected on the biomass char surface, and the activation energy of the gasification reaction decreased gradually with increasing potash content. Compa：red with the shrinking unreacted-core model, the homegeneous model is more suitable for describing the gasification reaction of deashing biomass char with C02 due to its extremely low ash content.