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The present work investigates the preparation of NiCe/γ-Al 2 O 3 coated cordierite monoliths for oxidative dehydrogenation of ethane (ODE) reaction through a two steps procedure: the primer deposition of a γ-Al 2 O 3 coating consisting in a mixture of micro and nanoparticles via the washcoating method and the latter incorporation of the active phase by impregnation. Moreover, a modification in these two steps was made: the suppression of some calcination steps to save energy in the manufacture process. The structured catalysts, named as Ni(X)Ce(Y)-M, where X = 13 or 19 wt%. Ni and Y = 5 or 8 wt%. Ce respectively, with respect to the alumina loading, were characterized by SEM/EDX, XRD, FTIR, LRS and XPS, and their catalytic activity was tested in the ODE reaction. Furthermore, their mechanical resistance to vibration was studied. Similar results corresponding to the un-promoted system are also presented for comparison. It was found that the co-impregnation of nickel and cerium was affected by the suppression of some calcinations: a preferential absorption of Ce rather than Ni occurred, generating at the end a catalytic coating with a higher Ce/Ni ratio than that of the precursor solution and a lower Ni loading than that of Ni(13)-M. On the other side, in the NiCe-based catalysts the properties of the active sites remained the same despite the increment in the active phase, at a fixed Ce/Ni nominal atomic ratio of 0.17. In the case of the Ni(19)Ce(8)-M system, although the Ni/Al atomic ratios were found lower than those of the nominal ones by EDX and XPS and ethylene selectivity decayed, ethane conversion resulted markedly higher, leading to an improved ethylene yield. [ABSTRACT FROM AUTHOR]

The reaction of H 2 S selective partial oxidation to elemental sulfur was studied on cordierite honeycomb-structured catalysts in the range of temperature of 150–200 °C. The preparation procedure of catalytic cordierite monoliths has been studied, from the washcoating with CeO 2 to the deposition of V 2 O 5 by wet impregnation. Two different preparation washcoating procedures deposition were studied: in one case the washcoat had been already added with the salts precursors of the active species ( joint impregnation method ), in other case the active species were added only after the deposition step of the washcoat on the monolith, by impregnation in a solution of the salt precursor ( distinct impregnation method ). The catalysts prepared with the two different methods were characterized and the stability was investigated in catalytic activity tests. The catalysts prepared with the “joint impregnation” method have shown a poor catalytic activity and tendency to the deactivation. Very different results were found for the catalysts prepared with the “distinct impregnation” method, for which the effect of the vanadium content (2–19 V 2 O 5 wt %) was also studied at 200 °C. Good catalytic performances were obtained for both samples that have shown a high H 2 S conversion (∼90%), low SO 2 selectivity (3%) and a high stability. The catalytic tests performed to varying the contact time with the temperature have allowed to identify the possible reaction pathway and the optimal operating conditions for which were obtained good catalytic performance. [ABSTRACT FROM AUTHOR]

Binary oxide systems (CuCr2O4, CuCo2O4), deposited onto cordierite monoliths of honeycomb structure with a second support (finely dispersed Al2O3), were prepared as filters for catalytic combustion of diesel soot using internal combustion engine's gas exhausts (O2, NOx, H2O, CO2) and O3 as oxidizing agents. It is shown that the second support increases soot capacity of aforementioned filters, and causes dispersion of the particles of spinel phases as active components enhancing thereby catalyst activity and selectivity of soot combustion to CO2. Oxidants used can be arranged with reference to decreasing their activity in a following series: O3 ≫ NO2 > H2O > NO > O2 > CO2. Ozone proved to be the most efficient oxidizing agent: the diesel soot combustion by O3 occurs intensively (in the presence of copper chromite based catalyst) even at closing to ambient temperatures. Results obtained give a basis for the conclusion that using a catalytic coating on soot filters in the form of aforementioned binary oxide systems and ozone as the initiator of the oxidation processes is a promising approach in solving the problem of comprehensive purification of automotive exhaust gases at relatively low temperatures, known as the "cold start" problem. [ABSTRACT FROM AUTHOR]

The deposition of catalytic layers as Rh, Pt, Ni (noble metals load equal to 1.5 wt.%, Ni load equal to 7.5 wt.%) on CeO 2 , over cordierite monoliths (400 cpsi, diameter 1 cm, length 1.5 cm), prepared through a combination of the solution combustion synthesis followed by the Wet Impregnation technique, was investigated. The performances of the structured catalysts were evaluated towards the methane Oxy-Steam Reforming (OSR) reaction. The physicochemical properties of the catalysts at powder level were investigated by X-ray Diffraction, CO chemisorption and nitrogen adsorption (BET), whereas the characteristics of the structured catalysts in terms of thickness and coating integrity were investigated by Scanning Electron Microscopy (SEM), mechanical strength and pressure drop tests. Moreover, the morphology of catalytic layers was investigated by Transmission Electron Microscopy (TEM) on the powder obtained by mechanically scraping the monoliths internal walls. The prepared structured catalysts were tested and compared towards the CH 4 OSR reaction varying the temperature (500–800 °C), the weight space velocity (WSV = 33,000–400,000 Nml g cat −1 h −1 ), at fixed molecular oxygen-to-carbon (O/C = 0.55) and steam-to-carbon (S/C = 1.2) molar ratios. The catalytic monoliths presented a uniform thin coating with thickness between 20 and 25 μm, high mechanical strength and low pressure drop. Regarding the catalytic activity, at low WSV all of the structured catalysts showed similar performances. Instead, increasing the WSV, the catalytic monolith loaded with 1.5 wt.% Rh/CeO 2 performed slightly better than the other samples, maintaining almost constant the methane conversion and the CO selectivity even at 400,000 Nml g cat −1 h −1 . [ABSTRACT FROM AUTHOR]

Abstract: The N2O decomposition and reduction by CO or C3H6 over rare earth oxides (REOs)-modified Pt/Al2O3 structured catalysts, i.e., coated on ceramic honeycomb monoliths, were comparatively investigated in a wide temperature interval of 100–600°C, either in the presence or in the absence of excess O2 and H2O. It was shown that the de-N2O efficiency can be remarkably enhanced via modification of Al2O3 support with rare earth oxides (REOs). In specific, complete conversion of N2O can be attained over REOs-modified catalysts at a relatively low temperature (ca. 480°C) even in the presence of excess O2, which in general depresses de-N2O efficiency, in opposite to the unmodified Pt/Al2O3 catalyst, over which, 20% N2O conversion is never exceeded for temperatures up to 600°C. In terms of turnover frequency (TOF), optimally modified (by REOs) Pt–Al2O3 catalyst exhibits one order of magnitude higher activity compared to that of the unpromoted Pt/Al2O3 sample. Under reducing conditions the N2O conversion is strongly enhanced by C3H6 and especially by CO, whereas marginal inhibition is induced by reducing agents under excess oxygen conditions. Water was found to induce a detrimental influence on N2O decomposition, with its effect however, to be partially reversible. An in situ diffuse reflectance infrared Fourier transform spectroscopic (DRIFTS) study, using CO as a probe molecule, was performed over both unmodified and REOs-modified Pt/Al2O3 catalysts to correlate their surface characteristics with their de-N2O efficacy. The results revealed that the superior catalytic performance of promoted samples could be mainly attributed to the increase of Pt dispersion as well as to the development of Pt sites with exceptional electron density, located on the metal–support interfacial area. [Copyright &y& Elsevier]

Abstract: CoFER and PtCoFER were prepared with different Co loadings and Co/Pt ratios. The resulting powders were washcoated on ceramic honeycombs. To increase adherence, silica was added to the slurry as a binder. The samples were assayed for the SCR of NO x with methane in excess oxygen. The maximum conversion of NO x to N2 for each formulation when plotted versus either Co loading or Co/Pt ratio presented maxima. All catalysts partially deactivated with 2% water. A thorough TPR, XPS and LRS characterization of fresh and deactivated catalysts showed that two deactivation mechanisms are operative. At low Co loadings, the formation of Pt clusters is responsible for the low selectivity, while for higher loadings Co3O4 is formed and is the non-selective species. [Copyright &y& Elsevier]

Bio-contamination of water through biofouling, which involves the natural colonization of submerged surfaces by waterborne organisms, is a global socio-economic concern, allied to premature materials bio-corrosion and high human health risks. Most effective strategies release toxic and persistent disinfectant compounds into the aquatic medium, causing environmental problems and leading to more stringent legislation regarding their use. To minimize these side effects, a newly non-biocide-release coating strategy suitable for several polymeric matrices, namely polydimethylsiloxane and polyurethane (PU)-based coatings, was used to generate antimicrobial ceramic filters for water bio-decontamination. The best results, in terms of antimicrobial activity and biocide release, showed an expressed delay and a decrease of up to 66% in the population of methicillin-resistant Staphylococcus aureus bacteria on ceramic filters coated with polyurethane (PU)-based coatings containing grafted Econea biocide, and no evidence of biocide release after being submerged for 45 days in water. Biocidal PU-based surfaces were also less prone to Enterococcus faecalis biofilm formation under flow conditions with an average reduction of 60% after 48 h compared to a pristine PU-based surface. Biocidal coated filters show to be a potential eco-friendly alternative for minimizing the environmental risks associated with biofouling formation in water-based industrial systems. [ABSTRACT FROM AUTHOR]