Contents lists available at ScienceDirect Applied Catalysis B: Environmental journal homepage: www.elsevier.com/locate/apcatb Cobalt mixed oxides deposited on the SiC open-cell foams for nitrous oxide decomposition A. Klegova 1, ⁎ , A. Inayat 1 , P. Indyka 2 , J. Gryboś 2 , Z. Sojka 2 , K. Pacultová 1 , W. Schwieger 3 , A. Volodarskaja 4 , P. Kuśtrowski 2 , A. Rokicińska 2 , D. Fridrichová 1,5 , L. Obalová 1 1 Institute of Environmental Technology, VŠB – Technical University of Ostrava, 17. listopadu 15/2172, 708 00 Ostrava, Czech Republic 2 Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland 3 Institute of Chemical Reaction Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerland, 91058 Erlangen, Germany 4 Faculty of Materials Science and Technology, VŠB – Technical University of Ostrava, 17. listopadu 15/2172, 708 00 Ostrava, Czech Republic 5 Centre Energy Units for Utilization of Non Traditional Energy Sources, VŠB – Technical University of Ostrava, 17. listopadu 15/2172, 708 00 Ostrava, Czech Republic ARTICLE INFO Keywords: N 2 O decomposition Cobalt mixed oxide Open-cell foam Supported catalyst SiC ABSTRACT Supported Co 3 O 4 and Co 4 MnAlO x mixed oxides were prepared by deposition on the SiC open-cell foams by wet impregnation and suspension methods and characterized by AAS, BET, XRD, SEM, TEM, TPR-H 2 , XPS and ni- trogen adsorption methods. Prepared supported catalysts as well as active phase Co 3 O 4 and Co 4 MnAlO x in grain form prepared from parent solutions were tested for nitrous oxide decomposition. Catalytic activity of grain active phase was governed by methods of preparation; Co 3 O 4 and Co 4 MnAlO x prepared by suspension method were significantly more active than those from solutions for impregnation method. Suspension method provided active phase with higher surface areas and sites with better reducibility, both of these factors contributed to higher N 2 O conversions. In contrast to this, N 2 O conversions over supported catalysts were dependent more on chemical composition of active phase than on method of preparation. Both catalysts containing Co 4 MnAlO x mixed oxide revealed higher conversion of N 2 O than catalysts containing Co 3 O 4 . STEM analysis of the most active Co 4 MnAlO x prepared by suspension method showed (i) segregation of Co 3 O 4 nanocrystals of cubocta- hedral shape containing (100) and (111) facets (this segregation was confirmed also by XPS and TPR-H 2 ) and (ii) Co-Mn-Al oxide nanoparticles with very small un-faceted grains assembled into elongated fiber-like agglomer- ates were observed by STEM. 1. Introduction Nitrous oxide (N 2 O) is considered as an important pollutant con- tributing to a greenhouse effect. The largest industrial sources of N 2 O emissions are waste gases from nitric acid production plants [1]. The low-temperature catalytic decomposition of N 2 O (up to 450 °C) to ni- trogen and oxygen offers an attractive solution for decrease of N 2 O emissions in tail gas from nitric acid production plants. Catalytic re- actor for N 2 O catalytic decomposition can be applied to the existing technologies and process does not require addition of a reducing agent. Important question is the choice of a suitable catalyst system. This catalyst must be active in the real waste gas conditions (in the presence of O 2 ,H 2 O and NO x ), stable, sufficiently selective and relatively cheap. Among tested catalysts, cobalt spinels such as Co 3 O 4 [2–8] and calcined layered double hydroxides (LDHs) containing cobalt Co [9], Co-Mg-Al [10], Co-Rh-Al [11], Co-Mn-Al [12–14] and Co-Cu [15] are very promising for N 2 O decomposition. To the best of our knowledge, only two research groups reported on manufacturing of shaped cobalt spinel based catalysts for low temperature N 2 O decomposition in pilot plant scale conditions [16–18]. In both cases, the conventional packed beds with pelletized cobalt spinel based catalysts were used for N 2 O decomposition. Disadvantage of this solution is that the catalytic re- action takes place only in a narrow surface region of the pellets due to internal diffusion limitation. This problem could be minimized by ap- plying of a thin active layer deposited on the supporting material. Usage of supported catalysts allows reducing of needed amount of expensive and sometimes also harmful active components in the catalyst, which lowers their price and can increase mechanical strength of the catalyst. The support can be in form of differently shaped pellets or as structured support, which commonly consists of ceramic or metallic substrates pre- shaped in the form of a single continuous structure with stable geo- metry. Supported cobalt oxide deN 2 O catalysts were studied mainly on https://doi.org/10.1016/j.apcatb.2019.117745 Received 25 February 2019; Received in revised form 6 May 2019; Accepted 14 May 2019 ⁎ Corresponding author. E-mail address: anna.klegova@vsb.cz (A. Klegova). Applied Catalysis B: Environmental 255 (2019) 117745 Available online 16 May 2019 0926-3373/ © 2019 Elsevier B.V. All rights reserved. T