Deactivation mechanisms and mitigation strategies for nickel-based acetylene semi-hydrogenation catalysts†

Abstract

Acetylene semi-hydrogenation is a crucial reaction in the ethylene purification industry, and nickel-based catalysts are widely studied due to their low cost and excellent hydrogenation activity. However, the catalytic stability of these catalysts remains a significant challenge, with unclear deactivation mechanisms and a lack of effective strategies. In this paper, we used techniques such as hydrogen-programmed temperature reduction coupled with on-line mass spectrometry (H₂-TPR-MS), in situ Fourier transform infrared spectroscopy (in situ FT-IR) under reaction conditions, and Diffuse Reflectance Infrared Fourier Transform Spectroscopy with CO as a probe molecule (CO-DRIFTS) to uncover a non-classical deactivation mechanism for supported nickel-based catalysts. Specifically, we discovered that the active Ni component interacts with hydroxyl groups on the support surface under reaction conditions, leading to the formation of inactive NiO_x species. This interaction alters the electronic structure of the active Ni sites, affecting the adsorption and activation of acetylene, and ultimately results in gradual catalyst deactivation. Based on these findings, we proposed a strategy to modify the support surface and weaken this interaction, which enabled the design of highly stable nickel-based catalysts.