基于铁酸钙载氧体的稻壳化学链气化反应特性

铁酸钙载氧体(CaFe2O4/Ca2Fe2O5，简称CF)具有弱氧化性，在化学链气化过程中对CO选择性高，且可以通过碳酸化反应捕集CO2，提高合成气的低位发热量。分别在热重分析仪和固定床反应器上对基于铁酸钙载氧体的稻壳（简称R）化学链气化反应特性进行研究，分析铁酸钙载氧体与CO2的碳酸化反应特性，考察铁酸钙载氧体与稻壳的质量比(mCF/mR)、反应温度和循环反应次数对稻壳化学链气化特性的影响，并采用XRD和SEM等手段对载氧体进行表征。结果表明：当反应温度为370~840 ℃时，铁酸钙载氧体与CO2发生碳酸化反应；当反应温度为800 ℃、mCF/mR =0.73时，反应器出口合成气的CO2产率较低，低位发热量最高；经过10次化学链循环气化反应，CaFe2O4循环再生能力良好，但铁酸钙载氧体的碳酸化反应性能下降。

Characteristics of Rice-Hull Chemical Looping Gasification With Calcium-Ferrite as Oxygen Carrier

Calcium ferrite oxygen carrier (CaFe2O4/Ca2Fe2O5) has a weak oxidizing property and high selectivity to CO. It can absorb CO2 by carbonation reaction, improving the low heat value of syngas during biomass chemical looping gasification (CLG) process. The evaluation of rice-hull CLG using calcium-ferrite as oxygen carrier was conducted via a thermogravimetric analyzer and a fixed bed reactor. Characteristics of carbonation reaction was analyzed, and the effects of mass ratio of calcium ferrite oxygen carrier (mCF/mR) to rice-hull, reaction temperature and cycle numbers on the performance of biomass CLG process were explored. XRD and SEM were used to characterize the fresh and reacted oxygen carriers. The results indicate that calcium-ferrite oxygen carrier can react with CO2 from 370 ℃ to 840 ℃. When the temperature is 800 ℃, the syngas with low CO2 yield and the highest low heat value is achieved by mCF/mR =0.73, in rice-hull CLG process with calcium-ferrite as oxygen carrier. After 10 times cyclic reactions, the calcium-ferrite oxygen carrier remains good recyclability，but the carbonation property decreases slightly.