Dry methane reforming with nickel–cobalt bimetallic catalysts based on halloysite nanoclay modified by alkaline melting method

Abstract

AbstractCatalysts, including (10% Ni)/AMHA, (10% Ni + 5% Co)/AMHA, (5% Ni + 5% Co)/AMHA, and (5% Ni + 10% Co)/AMHA, were prepared by simultaneous impregnation of Ni and Co on alkaline molten halloysite (AMHA) and characterized by X‐ray diffraction (XRD), field diffusion scanning electron microscopy (FESEM), temperature‐programmed reduction (TPR), temperature‐programmed oxidation (TPO), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), atomic force microscopy (AFM), and Brunauer–Emmett–Teller (BET). The catalysts were evaluated in dry reforming of methane (DRM) at temperatures of 700 to 850°C and with a volumetric composition of a feed gas of 40% CH4, 40% CO2, and 20% Ar in a fixed bed reactor. Catalyst performance tests showed that the nickel catalyst based on milled and alkaline molten nano‐halloysite had a relatively poor performance. After impregnation of cobalt metal with different concentrations in the presence of nickel, the functional properties increased. Characteristic observations and experiments showed a very positive effect of cobalt metal on the catalyst performance. The presence of cobalt reinforcing metal along with nickel improves the activity and stability and reduces catalyst coking. Moreover, increasing cobalt along with nickel leads to better dispersion of the active phase of nickel, improved catalyst regeneration, and stable production of synthetic gas from methane and carbon dioxide. The effect of cobalt and nickel ratio on the catalyst structure, conversion rate of methane and carbon dioxide, stability, and carbon deposition rate were investigated. The conversion rate increases at high temperatures. Also, the resulting gas composition is suitable for Fischer–Tropsch reactions.