Syngas production via CO2 reforming of methane over plasma assisted synthesized Ni-Co/Al2O3-ZrO2 nanocatalysts with different Ni-loadings

Ni-Co/Al2O3-ZrO2 nanocatalysts with 5, 10 and 15wt.% nominal Ni content have been prepared by impregnation followed by a non-thermal plasma treatment, characterized and tested for dry reforming of methane. For nanocatalysts characterization the following techniques have been used: XRD, FESEM, TEM, EDX dot-mapping, BET, FTIR and XPS. The dry reforming of methane was carried out at different temperatures (550-850 degrees C) using a feed mixture of CH4:CO2 (1:1). Among the nanocatalysts studied, the catalyst with the medium Ni content (10wt.%) was the most active in dry reforming of methane. This higher activity exhibited by Ni-Co/Al2O3-ZrO2 catalyst with medium Ni content (10wt.% ) can be attributed to small and well dispersed particles of Ni within the catalyst. Apart from the narrow surface particle size distribution in the case of Ni(10wt.%)-Co/Al2O3-ZrO2, the presence of small active components with average size of 7.5nm is proposed to be the reason for the superior performance of the catalyst. Ni(10wt.%)-Co/Al2O3-ZrO2 nanocatalyst had maximum surface area and the lower surface area was observed in the case of Ni(5wt.%)-Co/Al2O3-ZrO2 and Ni(15wt.%)-Co/Al2O3-ZrO2 due to the formation of the larger agglomeration and higher mean particle size of nickel particles, respectively. Although, GHSV enhancment had inverse effect on product yield but yield reduction for Ni-Co/Al2O3-ZrO2 catalyst with 10wt.% Ni was less drastic at high GHSVs. According to XRD and XPS, existence of NiAl2O4 confirms strong interaction between Ni and support but higher loadings of Ni resulted in less NiAl2O4; loser interaction between support and active phase. Small particles of active components and well-defined dispersion of them in Ni(10wt.%)-Co/Al2O3-ZrO2 nanocatalyst resulted in stability of the catalyst for either feed conversion or H-2/CO molar ratio. Copyright (c) 2013 John Wiley & Sons, Ltd.