非等温热重分析研究生物质催化气化特性

Biomass Catalytic Gasification Kinetics using Non-isothermal TGA

以CaO、MgO和Fe2O3为催化剂,使用非等温热重分析研究了典型农业生物质催化气化特性及反应动力学。在非等温法中,Doyle和Coats-Redfern近似函数都可以模拟生物质气化反应过程。通过对比这两个函数拟合实验数据的相关系数,确定在使用非等温法研究生物质反应动力学时,使用Doyle函数是求取反应动力学参数的较好方法。结果表明,在1090～1268K区间内,添加CaO的谷壳样表观活化能比谷壳的大,而添加MgO和Fe2O3的谷壳样表观活化能与谷壳的相比,分别下降了32.6%和14.4%以上,这与谷壳在不同催化剂作用下反应速率与温度关系图反映的特性是一致的,可以得出3种催化剂催化活性大小顺序为MgO>Fe2O3>CaO。最后给出了谷壳在热解阶段及焦炭气化阶段的反应动力学方程。

Using calcium oxide, magnesia and ferric oxide as catalyst, the properties and reaction kinetics of typical agriculture biomass catalytic gasification were investigated using non-isothermal TGA. In non-isothermal TGA, Doyle and Coats-Redfern approximate function could be used to simulate biomass gasification behaviors. After comparing correlation coefficient of approximate simulations, it was found that the better method to calculate gasification kinetics parameters was Doyle approximate function in non-isothermal TGA analysis. The results indicated that in the range of 1090- 1268 K, calcium oxide could raise the activation energy of rice husk. On the contrast, magnesia and ferric oxide could change the activation energy lower to more than 32.6% and 14.4% separately. It was also found that the catalytic activity order of the three catalysts was MgO〉Fe2O3〉CaO from variation of reaction rates with temperature for rice husk at different catalysts. At last gasification kinetics equations of rice husk were given.