CaO和MgO复合催化神木煤焦-CO_2气化的特性研究

Study of CaO and MgO Composite Catalytic Gasification on Shenmu Coal Char

利用常压等温CO_2气化的方法,研究了单组分CaO、MgO及CaO/MgO不同复合配比对神木煤焦催化气化的反应特性影响。结果表明:分别添加单组分催化剂CaO和MgO后,煤焦的气化反应活性得到了明显增强,并且CaO的催化作用要强于MgO;2种单组分催化剂添加量存在一个最优值,且均为15%,此时催化强度分别是原煤焦的5.67和2.37倍,当催化剂添加量超过这个最优值后,催化剂对气化的催化作用开始减弱;添加10%的不同CaO/MgO配比的复合催化剂,其催化效果明显强于相同含量的2种单组分,且900℃时存在一个最佳配比比例4:1,最佳配比下,催化强度是原煤焦的5.32倍,是添加10%CaO的1.69倍,是添加10%MgO的2.83倍。Takarada法计算了复合催化剂各工况下的反应性指数R,更直接地反映出了不同配比的复合催化剂对煤焦气化的影响。用未反应核收缩模型能够很好地描述煤焦-CO_2的气化反应过程;添加单组分催化剂煤焦的活化能相比原煤焦变化不大,而添加复合催化剂煤焦的活化能有一定程度的升高。

The catalytic gasification characteristics of adding single CaO, single MgO and the composite catalysts of different CaO/MgO proportion on Shenmu coal chars were analyzed under isothermal and ordinary pressure conditions. The results show that the char gasification reactivity was enhanced when adding single CaO or single MgO to in the coal char, and the catalysis of CaO is stronger than that of MgO. Both optimal adding amount of catalysts are 15%, when the catalyst adding amount exceed the optimal value, the promoting function of catalyst start to diminish. Add 10% of the different CaO/MgO proportion of the composite catalysts, the catalytic effect is obviously superior to any same content of single components, and a 4：1 ratio is the optimal ratio under 900 ~C. The catalytic intensity is 5.32 times higher than that of raw char, and 1.69, 2.83 times higher than those of CaO, MgO respectively. Takarada method is applied to calculate the reaction of the index R of the composite catalysts under various operating conditions, the influence of char gasification of the different proportion of the composite catalysts are more obvious reflected. The coal char- CO2 gasification reaction can very well be indicated by the reaction less core-shrinking model. The activation energy of adding single catalyst is largely equal to that of raw char~ however the activation energy of compound catalysts increases in certain degrees.