Contents lists available at ScienceDirect Catalysis Today journal homepage: www.elsevier.com/locate/cattod Use of pillared clays in the preparation of washcoated clay honeycomb monoliths as support of manganese catalysts for the total oxidation of VOCs José M. Gatica a, ⁎ , Jorge Castiglioni b , Carolina de los Santos b , M. Pilar Yeste a , Gustavo Cifredo a , Martín Torres b , Hilario Vidal a a Departamento C.M. I.M. y Química Inorgánica, Universidad de Cádiz, Puerto Real 11510, Spain b Laboratorio de Fisicoquímica de Superficies, DETEMA, Facultad de Química, Universidad de la República, 11800 Montevideo, Uruguay ARTICLE INFO Keywords: Environmental catalysis Honeycomb monoliths Manganese Pillared clays VOCs oxidation ABSTRACT Manganese catalysts supported by impregnation onto honeycomb monoliths extruded from commercial clay, previously coated with aluminium-pillared clay, were prepared and tested in the total combustion of propane and acetone. Samples characterization included chemical analysis, nitrogen physisorption, electron microscopies (SEM-EDS, HAADF and EELS), XRD, TPR and O 2 -TPD experiments. The active phase (around 5 wt%), consisting of MnO 2 particles as majority phase, with homogeneous size and shape, that tends to concentrate in some regions of the surface of the clay support, exhibited high efficiency to oxidize the two model VOCs investigated and stability in severe reaction conditions. Light-off temperatures as low as 225 and 330 °C were found for the oxidation of acetone and propane respectively. The better performance observed in comparison to the monoliths without pillared clay was attributed to the higher active phase loading. Differences found as function of the VOC's nature and concentration were related to the different oxidation mechanisms proposed in literature, either just Mars-van Krevelen or this with also Eley-Rideal contribution, for acetone and propane respectively. These results combined with the intrinsic advantages of the honeycomb monolithic design open up new possibilities for using pillared clays as catalytic support in VOCs oxidation under more affordable conditions. 1. Introduction Literature related to the use of manganese-based oxides as alter- native to noble metals for the abatement of VOCs is so far extensive, dealing with both pure manganese oxides [1–4] or Mn-containing mixed oxides [5] and MnO x deposited onto various supports [6–8], not only in the form of powders but also onto honeycomb monoliths, either using cordierite, washcoated with high surface alumina [9], or metallic substrates [10–12]. On the contrary, it is surprising that references which employ Mn-based catalysts supported onto clays for this application are much scarcer [13], in spite of the fact that clays are cheap and abundant materials, and that many of them possess ideal rheological properties for preparing structured supports by extrusion. Pillared clays with large surface area can be also used as supports for metal catalysts to achieve homogeneous dispersion, increased reactant adsorption area, and shape selectivity [14]. The utilization of clays pillared with transition metal oxides has been extended to reactions such as the dehydrogenation of cyclohexane to benzene [15], the Fischer–Tropsch synthesis [16], the selective catalytic oxida- tion of H 2 S [17], the selective catalytic reaction of NO [18], the hydrodesulfurization of thiophenes [19], and selective organic trans- formations [20], among others. In these examples, the activity is intrinsically associated to the metal oxides acting as pillars, but in other occasions the active phase is further incorporated by impregna- tion on the pillared clays surface area, which has been also done to prepare supported Mn oxides [21]. The traditional methods for preparing pillared clays are carried out in very diluted systems, so the contact between the clay in suspension and the intercalating solution allows diffusion of cations, used as pillared precursors, into the clay sheets, generating a homogeneous pillars structure [22,23]. However, their scale up for their industrial production remains a challenge (time-consuming processing, high volumes handling and lack of reproducibility) [24,25]. Therefore it is of great interest the development of optimized standard procedures or experimental techniques for the use of such materials. Recently the use of concentrated dispersions and microwave or ultrasound irradiation during the intercalation step have been proposed [26–28]. Another alternative might be to deposit pillared clays onto honeycomb mono- liths as a way to minimize the amount of pillared clay needed, maximizing the contact with active phases, while taking profit of the http://dx.doi.org/10.1016/j.cattod.2017.04.025 Received 12 January 2017; Received in revised form 28 March 2017; Accepted 10 April 2017 ⁎ Corresponding author. E-mail address: josemanuel.gatica@uca.es (J.M. Gatica). Catalysis Today xxx (xxxx) xxx–xxx 0920-5861/ © 2017 Elsevier B.V. All rights reserved. Please cite this article as: Jose Manuel, G.M., Catalysis Today (2017), http://dx.doi.org/10.1016/j.cattod.2017.04.025