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Abstract: Two methods for modifying a clay mineral by pillaring and delamination were studied to obtain suitable catalyst supports for Co and Cu. The arrangement of the active species and the interaction that they may have with the support will be a fundamental feature for activity and selectivity in the oxidation reactions. Moreover, the use of natural materials such as clay minerals will add value to these materials and allow them to be excellent supports for environmental impact reactions. The combination of transition metals in equimolar ratios leads to cooperative effects between the species, resulting in the excellent catalytic performance in oxidation reactions of VOCs. Based on structural and morphological characterization using XRD, SEM, H2-TPR, textural analysis and the evaluation of the catalytic activity in the oxidation of ethanol, the delaminated system proved to be a more appropriate support. [Copyright &y& Elsevier]

Abstract: We report the synthesis of four manganese catalysts supported on SBA-15 via a multistep impregnation method. The successive impregnations allowed as much as 13.8% manganese to be deposited without loss of the mesoporous structure of the SBA-15, although the surface area of the catalysts and their pore size distributions were lower than those of the pure SBA-15. The data obtained using different analysis techniques indicate that the manganese was incorporated into the pure SBA-15 in different positions: grafted onto the internal surface of the walls, incorporated into the framework of the SBA-15 and on the external surface and at the pores mouth of the SBA-15, which partially blocked the porosity. The XRD results showed that cryptomelane phase was formed in all of the catalysts; the remaining P123 in the SBA-15 structure and the presence of K+ during the impregnation most likely favored the formation of the cryptomelane phase. Total oxidation of ethyl acetate in air was obtained at temperatures less than 350°C for all of the catalysts. [Copyright &y& Elsevier]

Abstract: In this study, we evaluated the effect of ceria–zirconia content on the performance of Pt/x%CeZrO2/Al2O3 (x =0–40wt.%) during partial oxidation of methane. X-ray diffraction results indicated that, for samples containing 10 and 20wt.% of CeZrO2, there was the formation of a homogeneous solid solution between ceria and zirconia. On the other hand, for Pt/30%CeZrO2/Al2O3, there was the formation of a ceria rich phase and a zirconia rich phase whereas a ceria rich phase and an isolated zirconia phase were detected for Pt/40%CeZrO2/Al2O3. Catalytic tests showed that Pt/Al2O3 exhibited a significant deactivation, while Pt/10%CeZrO2/Al2O3 and Pt/20%CeZrO2/Al2O3 practically did not loose their activity after 24h. A deactivation was detected for Pt/30%CeZrO2/Al2O3 and Pt/40%CeZrO2/Al2O3. The higher stability of the Pt/10%CeZrO2/Al2O3 and Pt/20%CeZrO2/Al2O3 catalysts was attributed to the high reducibility and consequently the high oxygen mobility of the homogeneous solid solution formed, which promoted the mechanism of carbon removal from the metallic particle. [Copyright &y& Elsevier]

Abstract: The purpose of this study was to evaluate the effect of the precursors on the synthesis of MnO x -SBA15 catalysts. The influence of the manganese phase on the activity of catalysts in the complete oxidation of ethyl acetate was also tested. SBA15 was synthesized according to a standard method reported in the literature and manganese was introduced onto the support following an incipient wetness method using three different precursors. The catalysts were characterized by N2 adsorption, XRD, FTIR, TPR and HAADF and HRTEM microscopy. Then, they were tested in the oxidation of ethyl acetate. The results showed on one hand that the crystalline phase of deposited MnO x depended on the precursor used for the impregnation and on the other, that the manganese oxide was deposited both on the external surface and inside the mesoporosity of the SBA15 that preserved it structure, although it lost textural properties by pore blockage. The activity of the catalysts depended on the crystalline phase, being the most active those with Mn4+/Mn3+ pairs. [Copyright &y& Elsevier]

Abstract: The most convenient way to prepare structured manganese oxide catalyst for the combustion of volatile organic compounds was studied. The preparation conditions (solid concentration in the slurry, the addition of a suspension stabilizer, and the immersion numbers) were studied. The catalytic properties of these catalysts were evaluated in ethanol, ethyl acetate and toluene combustion. The surface area and the catalytic activity of monoliths in VOCs combustion increased with the amount of catalyst retained. A higher catalyst loading and a more homogeneous and well adhered layer was obtained using a 30wt% solid content suspension and performing two immersions. The addition of Nyacol® is not necessary to improve the stability of suspensions because these are stable by themselves. The washcoating of monoliths with a θ–δ-Al2O3 suspended in manganese acetate solution not only reduces the number of stages during the preparation procedure but also produces more active catalysts. [Copyright &y& Elsevier]

Abstract: In this work aluminium foams were studied as structured supports for the elimination of volatile organic compounds (VOCs, toluene). Foams of different pore density, 10, 20 and 40pores per inch (ppi), were used in an anodisation process to produce a very thin layer of alumina. This alumina layer was impregnated with the active phase, platinum, by wet impregnation. Anodisation process variables (temperature, time and current density) and their effect on the alumina layer were studied. Finally, their catalytic activity was tested in the toluene complete oxidation reactions. Catalytic activity increases both with the increasing platinum content and with the pore density of the foam showing the importance of the mass-transfer phenomena (contact between the gas phase and the solid catalyst). [Copyright &y& Elsevier]