催化剂添加量对褐煤焦水蒸气气化反应性的影响

在固定床反应器中研究了碱金属K和碱土金属Ca对褐煤焦水蒸气气化的催化效果，考察了煤焦的气化反应性随催化剂添加量的关系，并采用扫描电子显微镜结合X射线能谱分析仪(SEM EDX)和XRD技术分析了煤焦和焦样气化残渣的晶相组成和表面形态。实验结果表明，K的催化活性比Ca的高，煤焦的气化反应性随K和Ca添加量的增大而提高，K和Ca的负荷饱和度均为10％。添加K和Ca催化剂的原煤制焦后，K和Ca分布在煤焦的表面。原煤焦气化残渣中主要含钙铝黄长石。添加K的煤焦及其气化残渣中主要含钙铝黄长石和Ca3Si2O7，XRD没有检测到含K的晶体。当Ca的添加量从5％升高到10％时，煤焦表面有大量的CaO存在，但由于CaO发生团聚使其分散度降低。Ca添加量为10％的煤焦气化残渣中除了钙橄榄石和钙铝黄长石，还有未与矿物质反应的CaO和Ca(OH)2。

Effect of catalyst loadings on the gasification reactivity of a lignite char with steam

The effects of alkali and alkaline earth metals (K, Ca) on the steam gasification of a lignite char were investigated with a fixed bed reactor. The gasification reactivity of the chars with different catalyst loadings was examined. The crystallite constituents in the char and its gasification residue were identified by X ray diffraction (XRD). The morphology of the chars and the catalyst dispersion were analyzed by scanning electron microscope (SEM) equipped with an energy dispersive X ray analyzer (EDX). The results show that the catalytic effect of potassium is higher than that of calcium. The reactivity of chars increase linearly with catalyst loadings up to a loading saturation level (LSL) which is about 10% for both K and Ca. K and Ca were identified by EDX on the surface of chars produced from the raw coal samples loaded with potassium carbonate and calcium nitrate respectively. Gehlenite is the major constituent in the gasification residue of raw char. Gehlenite and rankinite are the major crystallites from chars loaded with potassium carbonate and their residues, but the crystallite with K is not detected by XRD. Large amount of calcium oxide attached to the char surface and the catalyst dispersion deteriorates due to agglomeration when the calcium loading is above the LSL. In addition to gehlenite and larnite, calcium oxide and calcium hydroxide uncontaminated by mineral matter are detected in the gasification residue from char loaded with 10% calcium.