Through use of the hydrothermal technique, various shaped CeO₂ supports, such as nanocubes (CeO₂-C), nanorods (CeO₂-R), and nanoparticles (CeO₂-P), were synthesized and employed for supporting Ni species as catalysts for a maleic anhydride hydrogenation (MAH) reaction. The achievements of this characterization illustrate that Ni atoms are capable of being incorporated into crystal lattices and can occupy the vacant sites on the CeO₂ surface, which leads to an enhancement of oxygen vacancies. The results of the MAH reaction show that the morphology and shape of CeO₂ play an important role in the catalytic performance of the MAH reaction. The catalyst for the rod-like CeO₂-R obtains a higher catalytic activity than the other two catalysts. It can be concluded that the higher catalytic performances of rod-like CeO₂-R sample should be attributed to the higher dispersion of Ni particles, stronger support-metal interaction, more oxygen vacancies, and the lattice oxygen mobility. The research on the performances of morphology-dependent Ni/CeO₂ catalysts as well as the relative reaction strategy of MAH will be remarkably advantageous for developing novel catalysts for MA hydrogenation.

Supported metal catalysts are widely used in industrial processes, and the particle size of the active metal plays a key role in determining the catalytic activity. Herein, CeO₂-supported Ni catalysts with different Ni loading and particle size were prepared by the impregnation method, and the hydrogenation performance of maleic anhydride (MA) over the Ni/CeO₂ catalysts was investigated deeply. It was found that changes in Ni loading causes changes in metal particle size and active sites, which significantly affected the conversion and selectivity of MAH reaction. The conversion of MA reached the maximum at about 17.5 Ni loading compared with other contents of Ni loading because of its proper particle size and active sites. In addition, the effects of Ni grain size, surface oxygen vacancy, and Ni–CeO₂ interaction on MAH were investigated in detail, and the possible mechanism for MAH over Ni/CeO₂ catalysts was deduced. This work greatly deepens the fundamental understanding of Ni loading and size regimes over Ni/CeO₂ catalysts for the hydrogenation of MA and provides a theoretical and experimental basis for the preparation of high-activity catalysts for MAH.