Pre-reforming of n-tetradecane over Ni/MgO–Al₂O₃ catalyst: effect of added potassium on the coke resistance

Abstract

We investigated the pre-reforming of n-tetradecane (C₁₄H₃₀) over the K-promoted 50 wt% Ni/MgO–Al₂O₃ catalyst and also analysed the coke resistance. The 50 wt% Ni/MgO–Al₂O₃ catalysts were prepared by the deposition–precipitation method and 1–5 wt% of potassium was added to the catalyst using the impregnation method. The catalysts were characterized by ICP, XRD, H₂-chemisorption, H₂-TPR, and BET. The pre-reforming of n-tetradecane was performed under the reaction conditions of S/C = 4.0, GHSV = 3000 h⁻¹, and 400–450 °C. The Ni crystallite size increased, whereas the Ni dispersion and surface area of catalysts decreased with increasing amounts of K. The 50 wt% Ni/MgO–Al₂O₃ showed large amounts of coke deposition compared to the K-promoted catalysts. It was found that the K addition over 50 wt% Ni/MgO–Al₂O₃ catalyst was beneficial for coke removal by promoting the coke gasification. A 1 wt%K/50 wt% Ni/MgO–Al₂O₃ catalyst showed stable activity during pre-reforming at S/C = 4.0, GHSV = 3000 h⁻¹, and 400 °C. Furthermore, it had the lowest amount of surface coke, as observed by SEM, TEM, and TG analysis.