Abstract:

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 KHCO₃.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.

Key words:

CO₂减排, 钾基吸收剂, 碳酸化反应

摘要：

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，20 min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。

关键词:

CO₂减排, 钾基吸收剂, 碳酸化反应