NaBH₄-Assisted Synthesis of B–(Ni–Co)/MgAl₂O₄ Nanostructures for the Catalytic Dry Reforming of Methane

Carbon deposition on a catalyst surface is detrimental to the dry reforming of methane (DRM) reaction. The addition of boron (B) is found to be effective in lowering carbon deposition. In this study, bimetallic Ni, Co catalysts over MgAl2O4(MA) [B–(Ni–Co)/MA] with different Ni/Co ratios are synthesized by the NaBH4 reduction method and examined for DRM at 600 °C and atmospheric pressure. The NaBH4 plays crucial roles in reducing metal salt to metal, incorporating B, and enhancing the dispersion of active metallic species in a one-step catalyst preparation method. Rod-like Ni–Co alloy and B–(Ni–Co) nanostructures on the two-dimensional flakes of MA are observed. The Ni-rich B-containing bimetallic [B–(75Ni–25Co)] catalyst exhibits better methane and carbon dioxide conversions compared to other prepared catalysts. The turnover frequency (CH4) and produced syngas ratio of the B-catalyst are 1.5 and 1.04 times, respectively, higher than the non-B catalyst prepared by the traditional impregnation method with the same Ni/Co ratio. The catalyst [B–(75Ni–25Co)] exhibits higher activity and almost a steady conversion rate, while continuous decrement is observed for the non-B catalyst. Exceptionally low carbon deposition (∼3.6 times) was observed for B–(75Ni–25Co)/MA than the non-B catalyst. Furthermore, the density functional theory investigation also revealed that the adsorption energy (Eads) of carbon at various sites of 75Ni25Co significantly reduces by ∼0.5 eV in the presence of B, causing hindrance to the formation of carbon over the surface.