Abstract
Pretreatment conditions of catalysts are considered as the critical factors to synthesize the highly efficient catalysts for heterogeneous reactions. In this work, a series of MOF-derived CoCeOx nanocomposites pyrolyzed at different temperatures were prepared to elucidate the effect of pyrolysis temperature on the catalyst activity/stability in CO2 reforming with ethanol. In addition, the change of the physicochemical properties was determined using various characterization technique including XRD, TEM, BET, H2-TPR, Raman and XPS. Indeed, increasing the pyrolysis temperature from 550 °C to 750 °C resulted in less oxygen vacancies as well as weaker Co–Ce support in MOFs-derived CoCeOx catalysts, which could consequently decrease the catalytic performance. Moreover, the higher pyrolysis temperature could lead to the partial collapse of mesoporous structure. Particularly, the ratio of Ce3+/Ce4+ declined as follows: CoCe-550 (17.6%) > CoCe-650 (14.5%) > CoCe-750 (12.4%). After 40 h stability tests, conversion of carbon dioxide over CoCe-750 catalyst significantly decreased from 37% to 7% as well as the decline of ethanol conversion from 94% to 87% for CoCe-750 catalyst pretreated at the higher pyrolysis temperature. In contrast, no obvious deactivation was observed for CoCe-550 sample with mesoporous structure. Hence, the established structure-activity relationship could provide guidance on the design of efficient catalysts for other high temperature reactions.
Published Version
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