Effect of Support Calcination Temperature on the Low-Temperature Catalytic Performance of the Ni/MgAl ₂ O ₄ Catalyst toward <i>n</i> -Decane Steam Reforming

Reducing the reaction temperature has been a key challenge in the catalytic reforming of long-chain alkanes for hydrogen production, highlighting the importance of developing catalysts with enhanced low-temperature activity. In this study, the influence of the support calcination temperature on the performance of Ni/MgAl2O4 catalysts in n-decane steam reforming was investigated. By adjusting the calcination temperature, a balance between the structural stability and specific surface area of the MgAl2O4 spinel was achieved, thereby optimizing the dispersion and structural thermal stability of Ni, further enhancing the catalyst’s resistance to sintering at high temperature and improving the activity in low temperature. The results showed that increasing the calcination temperature can promote the formation of the MgAl2O4 spinel structure, contributing to a moderate metal–support interaction, which effectively anchors Ni species and suppresses their migration and agglomeration under high-temperature conditions. However, it also reduced the specific surface area of the catalyst, leading to an increase of NiO particle size and a decrease of Ni dispersion. Among the tested samples, the Ni/MgAl2O4 catalyst calcined at 750 °C exhibited both a stable MgAl2O4 structure and a relatively large surface area. The balanced acidity, high NiO dispersion, and effective metal–support interaction of NMA750 lead to the best catalytic performance in n-decane steam reforming. In particular, it exhibited excellent low-temperature activity at 600 °C, achieving a conversion rate of 89.8% and a hydrogen yield of 62.0%. This superior low-temperature performance is underpinned by a significantly low apparent activation energy of 70.38 kJ/mol, confirming its enhanced catalytic reactivity compared to catalysts calcined at other temperatures. Therefore, a calcination temperature of 750 °C is the most suitable for the MgAl2O4 support, and corresponding Ni/MgAl2O4 has the best catalytic activity, especially for low-temperature steam reforming.