On the kinetics of Mn2O3/ZrO2 oxygen carrier for chemical looping air separation

Publication date: Available online 3 January 2019Source: Chemical Engineering and Processing - Process IntensificationAuthor(s): Yang Cao, Boshu He, Wenxiao Tong, Huifeng Yao, Zhipeng DuanAbstractChemical looping air separation (CLAS) is a novel oxygen generation technology with relatively small energy penalty. Thereby, CLAS can be efficiently integrated with the oxy-fuel combustion and the integrated gasification combined cycle (IGCC) technologies. The Mn-based oxygen carrier (OC) is a promising candidate for the CLAS process in the OC family, but its reactivity and stability are still unclearly determined. In this work, the equilibrium oxygen partial pressure of the Mn2O3/Mn3O4 system is firstly calculated. Then the reactivity and the stability of the impregnated Mn2O3/ZrO2 and Mn2O3/Mg-ZrO2 are assessed via the thermogravimetric analysis. The redox cycles of both the two kinds of samples are found unstable at high temperatures. The performance of the Mn2O3/ZrO2 is found much better than that of the Mn2O3/Mg-ZrO2, so only the redox kinetics of the Mn2O3/ZrO2 sample is determined at 725 − 800 °C. The Avrami-Erofeev random nucleation and subsequence growth model (A2) and the phase boundary reaction model (R3) are found to be the most suitable reaction mechanisms for the reduction and the oxidation processes, respectively. Interestingly, the reaction order is detected to increase exponentially with temperature for the oxidation reaction. Furthermore, the apparent acti...

Source: Chemical Engineering and Processing: Process Intensification - January 3, 2019 Category: Chemistry Source Type: research