Strategies to enhance dry reforming of methane: Synthesis of ceria-zirconia/nickel–cobalt catalysts by freeze-drying and NO calcination |
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Authors: | Moom Sinn Aw Ilja Gasan Osojnik ?rnivec Petar Djinovi? Albin Pintar |
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Affiliation: | 1. Laboratory for Environmental Sciences and Engineering, National Institute of Chemistry, Hajdrihova 19, SI-1001 Ljubljana, Slovenia;2. Centre of Excellence “Low Carbon Technologies”, Hajdrihova 19, SI-1001 Ljubljana, Slovenia |
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Abstract: | To improve the activity of nickel–cobalt (NiCo) catalyst supported on ceria-zirconia (CeZr) in the dry reforming of methane (DRM) with carbon dioxide, and to lower the coking rate in this process, 1.5 wt.% and 2.5 wt.% NiCo catalysts were prepared using two approaches, i.e. freeze-drying (FD) and NO calcination for comparison against oven-drying (OD) and air calcination (air), respectively. Their impact was studied for 20 h of DRM at 750 °C and 1.2 bar, with undiluted CH4–CO2 feed simulating the real conditions. NO-calcined samples show, on average, more pronounced improvement through increased conversion of CH4 (90%), followed by FD samples (85%) from the air and OD-prepared samples (both 82%). Coking content varied between 0.67 and 0.82 wt.%. The observed slow catalyst deactivation might be caused by sintering of the catalysts. Higher quantity of CO than H2 for syngas production was obtained, owing to concurrent reverse water-gas shift side reaction, and high redox properties of the defective CeZr lattice that enabled surface carbon gasification by continuous replenishment of oxygen from the support to produce CO, of which the latter phenomenon also explains the low carbon deposition. H2/CO ratio between 0.42 and 0.85 was achieved, with FD and NO samples fared better (0.83–0.85) over the ones prepared by conventional methods (0.73–0.82) for 2.5%NiCo loaded catalysts. |
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Keywords: | Ceria-zirconia support Dry reforming of methane Freeze-drying Nickel&ndash cobalt bimetallic catalyst NO calcination |
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