Preparation and Performance of Cerium-Based Catalysts for Selective Catalytic Reduction of Nitrogen Oxides: A Critical Review

Abstract

Selective catalytic reduction of nitrogen oxides with NH3 (NH3-SCR) is still the most commonly used control technology for nitrogen oxides emission. Specifically, the application of rare earth materials has become more and more extensive. CeO2 was widely developed in NH3-SCR reaction due to its good redox performance, proper surface acidity and abundant resource reserves. Therefore, a large number of papers in the literature have described the research of cerium-based catalysts. This review critically summarized the development of the different components of cerium-based catalysts, and characterized the preparation methods, the catalytic performance and reaction mechanisms of the cerium-based catalysts for NH3-SCR. The purpose of this review is to highlight: (1) the modification effect of the various metal elements for cerium-based catalysts; (2) various synthesis methods of the cerium-based catalysts; and (3) the physicochemical properties of the various catalysts and clarify their relations to catalytic performances, particularly in the presence of SO2 and H2O. Finally, we hope that this work can give timely technical guidance and valuable insights for the applications of NH3-SCR in the field of NOx control.

Nonisothermal cure behavior and kinetics of cerium‐doped Fe3O4/epoxy nanocomposites

“…There is also evidence for oxygen release by Ce in the structure of Fe 3 O 4 via the redox shift in between the Ce 4+ and Ce 3+ leading to charge compensating vacancies. [ 58 ] Overall, it can be concluded that the effect of Ce–Fe 3 O 4 nanoparticles on curing reaction of epoxy should be reflected in higher Δ H and consequently denser epoxy crosslinked network. To prove this, we capture the fingerprint of crosslinking of blank epoxy and epoxy nanocomposite systems for the sake of comparison.…”

The Emergence of the Ubiquity of Cerium in Heterogeneous Oxidation Catalysis Science and Technology

“…The acidic sites are active for ammonia adsorption and the rate determining step of the reaction of adsorbed ammonia (on either a Brønsted or Lewis acid site) with NO from the gas phase [131,132]. The method of catalyst preparation and incorporation of cerium into the catalyst was also shown to greatly affect cerium promotion [133] with the following order found for efficacy: hydrothermal treatment > sol-gel > co-precipitation > impregnation > mechanical mixing [134]. This order was attributed to maximizing the interaction of the catalyst components to enhance overall surface and lattice oxygen mobility as well as creating the surface acid sites necessary for the adsorption of the reactants.…”

A review on the characterization of metal active sites over Cu-based and Fe-based zeolites for NH3-SCR

“…For metal-based catalysts, many reviews focused on Mnbased oxides catalysts, [44][45][46][47] Ce-based oxides catalysts, 48 Febased oxides 49 and the CeO x -MnO x mixture catalysts 50 were published as those catalysts exhibited excellent lowtemperature (<100 C) in NH 3 -SCR. In addition, the latest progress on the vanadia-based and vanadia-free metal oxides catalysts had also been summarized.…”