钾基CO_2吸收剂的碳酸化反应特性

Carbonation reaction characteristics of dry potassium-based sorbent for CO_2 capture

对钾基CO2吸收剂的碳酸化反应机理进行研究。利用热重分析、XRD、扫描电镜和氮吸附仪进行试验。结果表明:分析纯碳酸钾的组分为K2CO3.1.5H2O,碳酸化反应速率缓慢;先将分析纯碳酸钾样品脱除结晶水后再进行碳酸化反应时,K2CO3与气氛中的水蒸气迅速生成K2CO3.1.5H2O,不利于碳酸化反应的进行;由KHCO3分解产生的K2CO3却表现出优越的碳酸化反应性能,20min内转化率高达85%以上,经过多次循环试验后吸收剂仍保持很高的活性。从微观角度分析了两种改性钾基CO2吸收剂碳酸化反应机理差异的原因,通过拟合计算得到了这3种钾基吸收剂的碳酸化反应速率常数,为干法K2CO3/KHCO3循环脱除CO2的研究提供了一定的基础数据。

The carbonation reaction characteristics of potassium-based sorbent was investigated with thermogravimetric apparatus （TGA）, X-ray diffraction （XRD）, scanning electron microscopy analysis （SEM） and N2 adsorption method. The results showed that the carbonation rate of analytical reagent （AR） K2CO3 was rather slow with its composition of K2CO3·1.5H2O. The carbonation rate of the K2CO3 sample without crystal water was also slow, because K2CO3 could react quickly with H2O from atmosphere to produce K2CO3·1.5H2O. However, the conversion rate of the sample reached 85% within 20 minutes, when K2CO3 was provided by decomposition of K2CO3. The sample still kept high activity after several cycles. The different reaction behavior of these samples were analyzed from the microscopic view. And the reaction mechanisms of these samples were discussed. Also the empirical equations of the reaction rates and the kinetic parameter were obtained by the thermal analysis method. The present work has provided the data base for the technology of dry potassium-based sorbent capturing of CO2.