CO Oxidation and Subsequent CO2 Chemisorption on Alkaline Zirconates: Li2ZrO3 and Na2ZrO3

Two different alkaline zirconates (Li2ZrO3 and Na2ZrO3) were studied as possible bifunctional catalytic-captor materials for CO oxidation and the subsequent CO, chemisorption process. Initially, CO oxidation reactions were analyzed in a catalytic reactor coupled to a gas chromatograph, using Li2ZrO3 and Na2ZrO3, under different O-2 partial flows. Results clearly showed that Na2ZrO3 possesses much better catalytic properties than Li2ZrO3. After the CO-O-2 oxidation catalytic analysis, CO, chemisorption process was analyzed by thermogravimetric analysis, only for the Na2ZrO3 ceramic. The results confirmed that Na2ZrO3 is able to work as a bifunctional material (CO oxidation and subsequent CO, chemisorption), although the kinetic CO, capture process was not the best one under the physicochemical condition used in this case. For Na2ZrO3, the best CO conversions were found between 445 and 580 degrees C (100%), while Li2ZrO3 only showed a 35% of efficiency between 460 and 503 degrees C. However, in the Na2ZrO3 case, at temperatures higher than 580 degrees C its catalytic activity gradually decreases as a result of CO2 capture process. Finally, all these experiments were compared and supported with theoretical thermodynamic data.