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Na-promoted Ni/ZrO2 dry reforming catalyst with high efficiency: details of Na2O-ZrO2-Ni interaction controlling activity and coke formation

Abstract

Herein, a 0.6 wt% Na-promoted 3%Ni/ZrO2 dry reforming catalyst and its unpromoted counterpart are discussed in details. Structural investigations were carried out by TEM, TPR, XRD, XPS, CO pulse chemisorption followed by TPD and DRIFTS methods. In presence of dry reforming mixture, bidentate carbonates were detected on Na-promoted Ni/ZrO2, while on Ni/ZrO2 the effective hydrogenation by metallic Ni converted bicarbonates to formate species. In the continuous flow atmospheric catalytic tests in high excess of methane, a reactive type coke was formed on the promoted sample, which did not cause significant deactivation. Temperature ramped 13CO2 isotope labeled dry reforming experiments in a closed loop sub-atmospheric circulation system revealed 13CH4 formation on Ni/ZrO2, while in the case of the promoted catalyst the methanation was retarded until the complete consumption of oxidants (from 13CO2). In isothermal experiments in the same circulation system carbon monoxide disproportionation was observed on Ni/ZrO2 leaving carbon on Ni, beside the coke formed from CH4 source, while on the promoted catalyst carbonaceous deposit under the same conditions did not form from CH4. The superb catalytic properties of Na-promoted Ni/ZrO2 are explained by a proposed catalytic cycle compiling the dynamic participation (formation and decomposition) of the surface Na2CO3 or NaHCO3 species surrounding the NiOxHy active sites on a ZrO2 support that is able to accommodate the labile Na2O promoter capturing and releasing CO2 oxidant.

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Publication details

The article was received on 18 May 2017, accepted on 05 Aug 2017 and first published on 07 Aug 2017


Article type: Paper
DOI: 10.1039/C7CY01011G
Citation: Catal. Sci. Technol., 2017, Accepted Manuscript
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    Na-promoted Ni/ZrO2 dry reforming catalyst with high efficiency: details of Na2O-ZrO2-Ni interaction controlling activity and coke formation

    M. Németh, D. Srankó, J. Károlyi, F. Somodi, Z. Schay, G. Sáfrán, I. E. Sajó and A. Horváth, Catal. Sci. Technol., 2017, Accepted Manuscript , DOI: 10.1039/C7CY01011G

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