Copper-Containing Mixed Metal Oxides (Al, Fe, Mn) for Application in Three-Way Catalysis

Tim Van Everbroeck,Radu-George Ciocarlan,Pegie Cool,Wouter Van Hoey,Myrjam Mertens

doi:10.3390/catal10111344

Tim Van Everbroeck, Radu-George Ciocarlan + Show 3 more

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https://doi.org/10.3390/catal10111344

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Abstract

Mixed oxides were synthesized by co-precipitation of a Cu source in combination with Al, Fe or Mn corresponding salts as precursors. The materials were calcined at 600 and 1000 °C in order to crystallize the phases and to mimic the reaction conditions of the catalytic application. At 600 °C a mixed spinel structure was only formed for the combination of Cu and Mn, while at 1000 °C all the materials showed mixed spinel formation. The catalysts were applied in three-way catalysis using a reactor with a gas mixture containing CO, NO and O2. All the materials calcined at 600 °C displayed the remarkable ability to oxidize CO with O2 but also to reduce NO with CO, while the pure oxides such as CuO and MnO2 were not able to. The high catalytic activity at 600 °C was attributed to small supported CuO particles present and imperfections in the spinel structure. Calcination at 1000 °C crystallized the structure further which led to a dramatic loss in catalytic activity, although CuAl2O4 and CuFe2O4 still converted some NO. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, H2-Temperatrue Programmed Reduction (H2-TPR), N2-sorption and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).

Highlights

Even with the most recent advances in alternatively-powered vehicles 86.8% of all the new-car registrations in the EU were fueled by diesel or petrol
After the calcination calcination at 600 °C, the aluminum is not detected as a crystal structure of Al2O3 or CuAl2O4, at 600 ◦ C, the aluminum is not detected as a crystal structure of Al2 O3 or CuAl2 O4, suggesting the suggesting the formation of amorphous alumina or small particles of CuAl2O4
In the case of CuAl 600, the Raman study confirmed that this sample contains γ-Al2 O3, which is described as having a defective spinel structure

Summary

Introduction

Even with the most recent advances in alternatively-powered vehicles 86.8% of all the new-car registrations in the EU were fueled by diesel or petrol. Petrol cars are using three-way catalytic convertors to abate the release of CO, volatile organic compounds (VOCs) (hydrocarbons) and NOx to the environment. This technology uses critical raw materials (CRMs) such as Pt, Pd and Rh as the main catalytic materials [2,3]. The reason why these materials are considered critical is related to their great economic importance, while their supply is at risk This means that the existing technologies need to be adapted in order to reduce the amount of CRMs. One way to reduce the use of CRMs is to replace them with alternative catalytic materials

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