Hydrogen production from methane dry reforming over nickel-based nanocatalysts using surfactant-assisted or polyol method

• Ni-based catalysts were prepared by polyol and surfactant-assisted methods.
• High H2 selectivity and yield were observed over polyol catalysts.
• Highly dispersed nano Ni-species were formed in polyol catalysts.
• Surfactant-assisted catalysts showed better coking resistance than polyol ones.
• RWGS reaction influenced the H2:CO ratio over surfactant-assisted catalysts.

In this study, two series of Ni-based nanocatalysts were synthesized successfully by the polyol and surfactant-assisted methods and subsequently tested for hydrogen production from CO2–CH4 reforming. Surfactant-assisted catalysts were prepared by using cetyl trimethyl ammonium bromide (CTAB) as a surfactant, whereas polyol catalysts were prepared in ethylene glycol (EG) medium with polyvinylpyrrolidone (PVP) as a nucleation-protective agent. The catalytic performance of each catalyst, in terms of H2 yield and selectivity, was evaluated at different temperatures (500–800 °C). In order to clarify and explain the differences in catalytic activities of catalysts, the prepared samples were characterized by various techniques, such as BET, H2-TPR, CO2-TPD, XRD, TGA, SEM, HRTEM and CO pulse chemisorption. The results demonstrated that the method of preparation had a significant effect on the catalytic performance of tested catalysts. Overall, polyol catalysts showed high activity and selectivity for hydrogen production, while surfactant-assisted catalysts exhibited a fairly high resistance towards carbon deposition under similar reaction conditions of dry reforming of methane. Moreover, due to the reverse water gas shift reaction (RWGS), surfactant-assisted catalysts always produced smaller values of H2/CO product ratio than their corresponding polyol catalysts.

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