Thermal Gravimetric Analysis Char-co <sub> 2 </ Sub> Catalytic Gasification Reactivity

With rapid development of Chinese economy, the demand for energy is increasing. The technology of coal gasification, as one of clean coal technology, has been highly favored for a long time. For the sake of improving gasification efficiency and lowering temperature of gasification, many laboratory studies about coal catalytic gasification were appeared. However, coal catalytic gasification has not been applied for any process of industrial production so far. The research explored of the catalytic gasification behavior of three different coals elementarily by TGA.This paper studied gasification behavior of Huangtumiao char, Jinjie char and Zhangminggou char which one-component catalysts with the same concentration were added in, and the results were carried out: except CaO, other catalysts showed varying degrees of catalytic activity. K₂CO₃ and Na₂CO₃ as the best accepted catalysts of coal gasification showed high catalytic activity for the three different types of coals, and Li₂CO₃ showed some role in lowering peak temperature of gasification. Over all, catalytic effect of alkali metal were better than transition metal and CaO. Moreover, different catalysts had different selectivity for different types of coals. Generally speaking, catalytic effect of compound catalyst was higher than any one of its constituent, the higher the catalytic activity of one-component catalyst was, the higher the activity of compound catalyst, and if the activity of one-component was higher, the proportion was more, then its contribution to the compound catalyst was greater. The catalytic effect of K₂CO₃ was best when the total concentration of K₂CO₃,(K₂CO₃+Li₂CO₃)(1:1) and (Na₂CO₃+K₂CO₃+Li₂CO₃)(1:1:1) was same, because the active temperature of every catalyst was different. There's hardly no impact of proportion in three-component catalyst to char gasification reactivity, so we should decide appropriate kind and ratio of catalyst according to the demand and characteristic of every catalyst.This paper also studied the impact of the type of coal, gasification temperature, concentration of catalyst and ash to catalytic gasification reactivity, and it showed that: catalytic gasification reactivity of Zhangminggou char was best, this suggested that catalytic effect of catalyst to high rank coal was superior to low rank coal; Increasing temperature favored enhancing carbon conversion rate and gasification reactivity of char, and increased gasification activity consequently; In a certain range(about ten percent to twenty percent), the efficiency of catalytic gasification of these coals was improved with increasing of the catalyst concentration, if catalyst concentration further increased, excessive catalyst deposition in coal surface would block the contact of gasification medium and active sites, and resulted in remaining constant even reducing of gasification reactivity finally; Gasification reactivity of raw char was higher than demineralization coal char during low temperature because of catalysis of ash, but it was opposite during high temperature; Gasification reactivity of demineralization coal char was higher than raw char in most of the time when added catalysts, so impediment effect of ash to coal gasification was greater than its catalysis.Kinetic parameters of some catalytic gasification of coal char were computed simply, and the parameters conformed to the experiment conclusion well.