Highly stable coke-resistant ethanol reforming over Ni–La catalyst: Effect of support

Abstract

Ethanol steam reforming (ESR) has proven to be a stable and efficient method of hydrogen production. The work aims to synthesize a coke-resistant ethanol-reforming catalyst with high stability. Herein, Ni–La metals were impregnated on different supports (hydrocalumite, Al₂O₃, SiO₂, and MgO), where the support was selected based on their specific properties, viz. high surface area, morphology, and basic/acidic nature. The physicochemical characteristics of synthesized catalysts were studied using a variety of characterization techniques, such as High resolution Transmission Electron Microscopy (HRTEM), Field Emission Scanning Electron Microscopy (FESEM), Brunauer Emmett Teller (BET), X-ray Diffraction (XRD), and H₂- Temperature Programme Reduction (TPR), and the catalyst activity was tested at fixed bed reactor at industrially relevant conditions (T: 600 °C, S/C ratio of 4.5). The variation in catalytic activity, stability, and the rate of coke formation was studied. Among the catalysts, Ni–La/hydrocalumite showed the highest catalytic performance, with ethanol conversion of 100 % and hydrogen yield of 4.6 mol/mol, and a very low rate of coke deposition of 1.33 (mg/gcat-h) was observed. Long-term activity tests also show that the catalyst is highly stable till 12 h with a slight decrease in ethanol conversion (∼3–4 %). The best performance of hydrocalumite catalyst is attributed to the basicity and structure of hydrocalumite, which provides reducible support, an effective metal-support interaction, and improves the dispersion of nickel, facilitating an efficient ethanol steam reforming process. In addition, coke resistant property of hydrocalumite provides long-term stability to the catalyst.