Effect of small quantities of potassium promoter and steam on the catalytic properties of nickel catalysts in dry/combined methane reforming

Carbon dioxide and methane are two of the principal greenhouse gases. Reduction of their content in the atmosphere is currently the subject of much worldwide research. Dry and combined reforming of methane are effective methods of CO₂ and CH₄ utilization and production of synthesis gas (syngas) in chemical technology. Testing of catalysts that provide the desired H₂/CO ratio and long operation time is one of the critical aspects of syngas production and the focus of much study. In this study, K-promoted Ni/MgAl₂O₄ catalysts prepared using a co-precipitation-impregnation method with different K/Ni ratios (range of 0–0.15) were examined in dry reforming of methane (DRM). The obtained catalysts were characterized using X-ray diffractometry (XRD), atomic emission spectrometry (MP-AES), Brunauer–Emmett–Teller (BET) specific surface area, BJH pore size distribution, TEM imaging, analysis of reducibility H₂-TPR, infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Hammet basicity analysis, thermogravimetric analysis (TG) and elemental carbon-hydrogen-nitrogen analysis (CHN). Promotion of nickel catalysts with potassium led to changes in nickel distribution, metal-support interactions and deceleration of carbon deposition while enhancing sorption of carbon dioxide and reduction of n_H2:CO to 0.5 for 0.7 K–Ni/MgAl₂O₄ catalyst. To obtain the required H₂:CO ratio close to unity a study on the effect of steam in inlet stream was performed. It was found that maintaining inlet stream composition equal CH₄:CO₂:H₂O = 1.0:1.0:0.1 obtained an H₂:CO ratio close to unity.