Promoting dry reforming of methane via bifunctional NiO/dolomite catalysts for production of hydrogen-rich syngas

Abstract

Extensive effort has been focused on the advancement of an efficient catalyst for CO₂ reforming of CH₄ to achieve optimum catalytic activity together with cost-effectiveness and high resistance to catalyst deactivation. In this study, for the first time, a new catalytic support/catalyst system of bifunctional NiO/dolomite has been synthesized by a wet impregnation method using low-cost materials, and it shows unique performance in terms of amphoteric sites and self-reduction properties. The catalysts were loaded into a continuous micro-reactor equipped with an online GC-TCD system. The reaction was carried out with a gas mixture consisting of CH₄ and CO₂ in the ratio of 1 : 1 flowing 30 ml min⁻¹ at 800 °C for 10 h. The physicochemical properties of the synthesized catalysts were determined by various methods including X-ray diffraction (XRD), N₂ adsorption–desorption, H₂ temperature-programmed reduction (H₂-TPR), temperature-programmed desorption of CO₂ (TPD-CO₂), and temperature-programmed desorption of NH₃ (TPD-NH₃). The highest catalytic performance of the DRM reaction was shown by the 10% NiO/dolomite catalyst (CH₄ & CO₂ conversion, χCH₄; χCO₂ ∼ 98% and H₂ selectivity, S_H2 = 75%; H₂/CO ∼ 1 : 1 respectively). Bifunctional properties of amphoteric sites on the catalyst and self-reduction behaviour of the NiO/dolomite catalyst improved dry reforming of the CH₄ process by enhancing CH₄ and CO₂ conversion without involving a catalyst reduction step, and the catalyst was constantly active for more than 10 h.