Porous Ni−Al−O Fabricated by a Facile Hydrothermal Method: Improved Catalytic Performance for the Oxidative Dehydrogenation of Ethane to Produce Ethylene

Abstract The oxidative dehydrogenation of ethane (ODHE) to ethylene is a process with many advantages (such as energy conservation and coke resistance). Herein, flower‐like Ni−Al−O catalysts with hierarchical structure and high surface areas were fabricated through a hydrothermal route and were applied to ODHE using O 2 as oxidant. Compared with NiO alone, the Al 3+ insertion into NiO matrix not only increases the C 2 H 4 selectivity by 3–4 times, but also prevents the generation of CO 2 and CH 4 above 500 °C. At 550 °C, all Ni−Al−O catalysts maintain approximately 50 % ethylene selectivity regardless of Al content. The ethylene yield of 29.5 % with C 2 H 4 selectivity 55.7 % over Ni−Al 0.8 ‐O sample can be reached at 500 °C. Moreover, the Ni−Al 0.8 ‐O catalyst presents a good stability and has no loss of activity after 100 h continuous evaluation. The various characterizations were carried out for investigating the nature of as‐prepared Ni−Al−O catalysts with different Al loadings. Experimental results demonstrate that the addition of Al not only affects the structure and texture properties of NiO, but also impacts the reducibility of Ni species and the amount of active oxygen species. It is found that the Al 3+ substitution results in: (1) smaller NiO size; (2) larger specific surface area; (3) weaker reducibility and (4) fewer non‐stoichiometric oxygen species. Therefore, the significant improvement of ethylene selectivity is observed in Ni−Al x ‐O catalysts.