High-Stability ZnAl₂O₄ Spinel-Supported Nickel Catalyst for High-Temperature Syngas Methanation

Abstract

The development of Ni-based syngas methanation catalysts with superior thermal stability remains a formidable challenge, which typically requires the use of a high Ni loading and a recipe containing very complex components. Herein, a novel Ni catalyst using a ZnAl 2 O 4 spinel support was designed and prepared by an isopropanol-mediated controlled hydrolysis method, which demonstrated excellent reactivity and stability toward the syngas methanation reaction. Moreover, the 35% Ni/ZnAl 2 O 4 catalyst still maintained a high reactivity after steam treatment at 750 °C, while the 35% Ni/Al 2 O 3 counterpart suffered a nearly complete loss of reactivity during such an accelerated test. The detailed characterization reveals that the drastic deactivation of Ni/Al 2 O 3 after steam treatment is attributed to the favored formation of NiAl 2 O 4 under the severe reaction atmosphere, resulting in the loss of active Ni. In contrast, the employment of the highly stable ZnAl 2 O 4 support can not only inhibit the sintering of supported Ni particles due to their strong interaction but also avoid the loss of the active Ni component by preventing the formation of NiAl 2 O 4 . This work sheds light on the critical role and the intrinsic mechanism of the spinel support for the construction of the desired methanation catalysts. The mechanistic scenario revealed in this work provides an important and novel solution to overcome the deactivation problem not only useful for methanation catalysts but also valid for most other supported metal catalysts commonly used in the reaction processes that require severe reaction conditions.