H2O-induced carbon disorder and metal sintering: The primary deactivation mechanism in Ni-Fe/ Al2O3 catalysts during alkaloid residue steam reforming

Ni-Fe bimetallic catalysts demonstrate high catalytic activity and strong resistance to deactivation during biomass steam reforming (BSR). However, their activation and reaction with steam (H 2 O) are complex, and a deeper understanding of the underlying mechanisms is crucial for enhancing catalyst stability. This study systematically investigates the influence of H 2 O on the deactivation mechanisms of Ni-Fe/Al 2 O 3 catalysts, focusing on its dual role in modulating carbon deposition patterns and triggering metal particle sintering. Our experimental results reveal a paradoxical effect of steam: the introduction of H 2 O reduces the total amount of carbon deposits, it promotes the formation of structurally disordered carbon. Crucially, this disordered carbon is identified as the primary driver of catalyst deactivation. It not only physically blocks active sites but also accelerates the sintering of metal particles, leading to profound alterations of the catalyst’s surface architecture and a consequent loss of performance. Combining experimental results and DFT calculations, we reveal the energy barriers for carbon evolution and correlate them with catalytic stability. These insights provide a theoretical foundation for improving the deactivation resistance of the catalyst, controlling the structural type of carbon deposits, and optimizing the anti-sintering performance of the etallic catalysts.