One-pot synthesis of NiO–MgO nanocatalysts for CO2 reforming of methane: The influence of active metal content on catalytic performance

• Solid solution NiO–MgO catalysts were prepared via one-pot sol–gel method.
• The mesoporous structure of the catalysts was largely independent of Ni content.
• Catalytic performance in CO2 reforming of CH4 changed strongly with Ni content.
• Optimal catalytic performance was achieved with moderate Ni content (10% NiO).
• First-order rate laws were appropriate for main reaction and catalyst deactivation.

In a new approach, a series of NiO–MgO solid solution catalysts with different NiO contents (5, 10, 15 and 20 wt %) were prepared by one-pot sol–gel/evaporation method. Nitrogen adsorption/desorption, XRD, TPR, TGA, SEM and TEM techniques were used to correlate the activity and stability to the structural properties of the catalysts. The catalysts exhibited mesoporous structures with high surface areas, large pore volumes and narrow pore size distributions. From 15% NiO content onwards, the TPR profiles showed evidence of isolated NiO phase from the solid solution. The catalytic performance was investigated for carbon dioxide reforming of methane in a fixed bed reactor (ID = 8 mm) at 550–750 °C and 1 bar with feed composition CO2/CH4 = 1 and space velocity of 30,000 ml/h.gcat. The Ni element showed uniform dispersion within the mesoporous matrix illustrating the advantage of the one-pot synthesis method. The Ni particle size was availably confined in this method. It was found that the catalytic activity and stability were strongly affected by the nickel content. The results were revealed that the 10% NiO/MgO catalyst calcined in 600 °C combined sufficiently high activity with slight coke formation and excellent catalytic stability at 750 °C during dry reforming reaction. Kinetic study revealed that the first-order rate laws were appropriate for main reaction and the catalytic deactivation.

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