Spontaneous regeneration of active sites against catalyst deactivation

Abstract

Catalyst deactivation is one of the long-standing challenges in heterogeneous catalysis. Here, we found that the Ni/MgAl2O4 catalyst shows an atmosphere-dependent deactivation behavior during dry reforming of methane (DRM) process, i.e., oxidation and redispersion of Ni near the inlet in an oxidizing atmosphere while coking and sintering of Ni near the outlet in a reducing atmosphere. These structural evolutions of the Ni species are revealed to be driven by the surface oxidation degree of the catalyst, such that it is reversible when the redox atmosphere changes. It inspired us to develop an alternating-feeding gas strategy that periodically changes the gas flow direction to balance the structural evolution of Ni species across catalyst bed through the spontaneous regeneration of deactivated sites, enabling a supra-stable DRM process. This study provides new insights into the catalyst deactivation for DRM process, while opens a new avenue to address catalyst deactivation in various redox-catalyzed processes.