Effect of alkaline earth oxides on nickel catalysts supported over γ-alumina for butanol steam reforming: Coke formation and deactivation process

• Published in: International journal of hydrogen energy Vol. 45; no. 43; pp. 22906 - 22920
• Main Authors: Menezes, João Paulo da S.Q., Dias, Adriana P. dos S., da Silva, Mônica A.P., Souza, Mariana M.V.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 03-09-2020
• Subjects: Basic promoters; Butanol; Coke; Hydrogen; Nickel; Steam reforming; Basic promoters; Butanol; Steam reforming; Nickel; Hydrogen; Coke
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2020.06.187

Nickel catalysts were synthesized by the wet impregnation of three different supports: γ-Al2O3 and alumina promoted with either 10 wt % of MgO or 10 wt% of CaO. The catalysts were evaluated in butanol steam reforming at 500 °C, atmospheric pressure, GHSV of 500,000 h−1 and 10% v/v butanol in the feed. Both promoters decreased catalyst acidity and increased basicity. The catalyst promoted with MgO exhibited the lowest acidity (1.1 μmolNH3 m−2), whereas that promoted with CaO, the highest basicity (870.7 μmolCO2 m−2). The promotion with MgO led to the highest hydrogen yield (66%) and stability, associated with its highest nickel dispersion (3.4%), lowest acidity and lowest coke formation normalized by carbon converted (3.0 mmol L mol−1). The catalyst promoted with CaO presented the most severe deactivation, associated with its lowest dispersion (1.0%) and the highest amount of encapsulated coke (3.5 mmol L mol−1).
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•Three Ni catalysts on different supports were evaluated in butanol steam reforming.•CaO and MgO addition decreased acidity and nickel aluminate formation on catalysts.•MgO addition increased nickel dispersion, while CaO decreased.•Ni/10% MgO–Al2O3 presented the highest H2 yield and stability at 500 °C for 30 h.•Coke formation was enhanced by acidity and large Ni crystals.