Porous stainless-steel fibers supported CuCeFeOx/Zeolite catalysts for the enhanced CO oxidation: Experimental and kinetic studies

Surface adsorbed and lattice oxygen activated by the CeO2/Co3O4 interface for enhancive catalytic soot combustion: Experimental and theoretical investigations

Metal oxide-oxide interface on supported catalyst has been rarely studied due to the complex interfacial structure and synthetic challenge. Herein, different Ag-supported CeO₂/Co₃O₄ samples with various covered-state of CeO₂ were prepared for catalytic soot oxidation. In comparison, catalytic activity was significantly improved by grafting CeO₂ on Co₃O₄, in which the best performing Ag/CoCe-2 exhibited remarkable catalytic performance towards soot oxidation with a T₅₀ of 290.5 ℃ under 10 % O₂/N₂. Catalyst characterization investigated by Scanning Electron Microscope (SEM), quasi in-situ X-ray Photoelectron Spectroscopy (XPS), in-situ Raman, etc. revealed that this outstanding promotion in catalytic activity can be principally ascribed to the formation of the CeO₂/Co₃O₄ interface. An appropriate CeO₂ dosage maximized the contact and interaction between Co₃O₄ and CeO₂, resulting in the largest CeO₂/Co₃O₄ interface featured with abundant generated superoxide species and activated surface lattice oxygen. Density functional theory (DFT) calculations were also carried out for the oxygen vacancy formation energy, Gibbs free energy, etc. In presence of the CeO₂/Co₃O₄ interface, a charge density redistribution around the adsorbed reactants at oxygen vacancies could be formed, owing to the efficient charge transfer enhanced by the electron-appealing effect. The change in electronic structure favored reducing the oxygen vacancy formation energy and boosting the lattice oxygen activation induced by the hybridized Co-O-Ce bonds, finally lowering the adsorption and activation barriers for reactive species and accelerating the reaction kinetics.

Stainless steel catalyst for air pollution control: structure, properties, and activity

With the awakening of environmental awareness, the importance of air quality to human health and the proper functioning of social mechanisms is becoming increasingly prominent. The low cost and high efficiency of catalytic technique makes it a natural choice for achieving deep air purification. Stainless steel alloys have demonstrated their full potential for application in a variety of catalytic fields. The diversity of 3D networks or fibrous structures increases the turbulence within the heterogeneous catalysis, balance the temperature distribution in the reaction bed and, in combination with a highly thermally conductive skeleton, avoid agglomeration and deactivation of the active components; corrosion resistance and thermal stability are adapted to highly endothermic/exothermic or corrosive reaction environments; oxide layers formed by bulk transition metals activated by thermal treatment or etching can significantly alter the physico-chemical properties between the substrate and active species, further improving the stability of stainless steel catalysts; suitable electronic conductivity can be applied to the electrothermal catalysis, which is expected to provide guidance for the reduction of intermittent emission exhausts and the storage of renewable energy. The current applications of stainless steel as catalyst or support in the air purification have covered soot particle capture and combustion, catalytic oxidation of VOCs, SCR, and air sterilization. This paper summarizes several preparation methods and presents the relationships between the preparation process and the activity, and reviews its application and the current status of research in atmospheric environmental management, proposing the advantages and challenges of the stainless steel-based catalysts.