Alkaline zirconates as effective materials for hydrogen production through consecutive carbon dioxide capture and conversion in methane dry reforming
In this work, H 2 production was evaluated using different carbonation conditions and two alkaline zirconates. For this purpose, Li 2 ZrO 3 and Na 2 ZrO 3 were synthesized, characterized and tested on a consecutive process composed of initial CO 2 capture, followed by methane dry reforming (MDR). Thermogravimetric results showed that under the four gas mixtures tested (diluted and saturated CO 2 , CO and CO-O 2 ), both ceramics are able to chemisorb CO 2 , with Na2ZrO3 having the highest capture with saturated CO 2 . In catalytic tests, ceramics carbonated with saturated CO 2 or CO-O 2 gas flows were able to act as sorbents and catalysts, producing H 2 at T > 750 °C through the partial oxidation of methane. This reaction was produced because CO2 desorption did not occur, thus avoiding the MDR process. On the other hand, carbonated ceramics under a CO-O2 gas mixture presented an outstanding catalytic performance. Between 450 and 750 °C, H 2 was formed through the MDR process promoted by CO 2 desorption from both ceramics. This result is in line with CO 2 desorption results, where a weaker CO 2 –solid interaction was observed in comparison with saturated CO 2 2. Afterward, both ceramics presented a similar catalytic behavior, good regeneration and cyclability after the double process proposed (CO 2 capture-MDR reaction). Lithium zirconate also presented high thermal stability during cycle tests; meanwhile, sodium zirconate showed an important H 2 production increase as a function of cycles. Finally, both materials are feasible options for producing a clean energy source in a moderate temperature range through the catalytic conversion of two greenhouse gases (CO 2 and CH 4 ).