NiO-CaO materials as promising catalysts for hydrogen production through carbon dioxide capture and subsequent dry methane reforming

In this work, CaO-NiO mixed oxide powders were evaluated as consecutive CO2 chemisorbents and catalytic materials for hydrogen production thought the CH4 reforming process. Between the NiO-impregnated CaO and CaO-NiO mechanical composite, the first one presented better chemical behaviors during the CO2 capture and CH4 reforming processes, obtaining syngas (H-2 + CO) as final product. Results showed that syngas was produced at two different temperature ranges, between 400 and 600 degrees C and at T > 800 degrees C, where the first temperature range corresponds to the CH4 reforming process but the second temperature range was attributed to a different catalytic reaction process: CH4 partial oxidation. These results were confirmed through different isothermal and cyclic experiments as well as by XRD analysis of the final catalytic products, where the nickel reduction was evidenced. Moreover, when a CO-O-2 flow was used during the carbonation process a triple process was achieved: (i) CO oxidation, (ii) CO2 chemisorption and (iii) CH4 reforming. Using this gas flow the hydrogen production was always higher than that obtained with CO2. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.