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Abstract: Two series of t-ZrO2 samples doped with 5mol% of alien Sm, Gd, Mo, Mn and V cations were synthesized by wet impregnation and calcined at 600°C or 1000°C for 6h, respectively. Structural (XRD) and spectroscopic (EPR, RS) characterization was completed by reducibility studies (TPR). Low-temperature NO adsorption, monitored by EPR, was investigated to find the link between structural properties of doped zirconia and activation modes of NO molecules. Relations between the chemical composition and dopant speciation, reducibility of the catalysts and the ways of NO adsorption were elucidated. [Copyright &y& Elsevier]

Abstract: Iron species formed by thermal treatment of iron- and aluminium-based ion exchanged MFI-type zeolites were investigated by IR and EPR spectroscopies and by the adsorption of NO as a probe molecule. The parallel investigation of the residual acidity by adsorption of pyridine allowed to calculate the number of acidic sites and the number of Lewis centres both in iron- and aluminium-based MFI zeolites. It was confirmed that the activation process could be divided into two regions, depending on temperature. At lower temperatures the main process is hydrolysis and thermal decomposition of precursors such as iron aquacomplexes and/or hydroxides, but at higher temperatures dehydroxylation and subsequent redox reaction, balancing the amounts of Fe(II) and Fe(III) ions, takes place. Combined EPR and IR studies showed that the process of thermal activation can be tracked over wide temperature range (from ambient temperature to 1020K) by following the properties of both ferrous and ferric sites and implied that at least the part of Fe cations cannot be observed by neither method, suggesting they adopt a form of bulk oxide-like species. [Copyright &y& Elsevier]

Abstract: The interaction of NO and O2 with 5mol.% of vanadia deposited on Ce0.10Zr0.90O2 and Ce0.69Zr0.31O2 supports by wet impregnation was studied by means of EPR and IR. The supports were structurally characterized by XRD and Raman spectroscopy. Influence of the phase composition of the support on vanadium speciation as well as on surface architecture of the oxovanadium entities was discussed. The NO forms adsorbed on vanadium-containing systems were compared to those observed on bare CeO2-ZrO2 supports. The main products appearing on the catalysts surface during the consecutive reaction with NO and O2 were identified and their thermal evolution was observed. Changes in vanadium speciation accompanying redox processes related to NO and O2 activation were also observed and discussed. [Copyright &y& Elsevier]

Abstract: Variable temperature adsorption of nitric oxide on MoO3 supported on tetragonal zirconia (MoO x /t-ZrO2), obtained by slurry deposition, was investigated by EPR spectroscopy. The influence of molybdenum loading and co-adsorbed oxygen on the adsorption process of NO was elucidated. Particular attention was devoted to redox character of NO activation. Another important aspect concerned is the nature of surface nitrosyl complexes of molybdenum and their thermal stability. The role of oxygen in NO transformation over catalyst surface was also discussed. [Copyright &y& Elsevier]

Abstract: The interaction of nitric oxide with Ce0.75Zr0.25O2 solid solution were investigated by means of EPR and IR spectroscopies. The influence of adsorption parameters such as adsorption temperature and pressure, presence of the O2 co-reactant on the nature and relative surface abundance of the resultant mono- and dimeric NO species was elucidated. The thermal stability of the surface nitrosyl complexes and their reactivity toward dioxygen were also examined. [Copyright &y& Elsevier]

Abstract: Structural (XRD) and spectroscopic (EPR, IR and Raman) investigations were performed to elucidate the influence of CeO2 content on the phase composition and surface chemistry of Ce x Zr1−x O2 solid solutions (x =0.10–0.85), interacting with NO and NO2 in the absence and presence of oxygen. Strong influence of ceria loading on the adsorption modes of both nitrogen oxides and the nature of the resultant surface species was revealed. Adsorption of NO led to formation of mononitrosyl complexes, dimers and N2O, whereas interaction of NO2 with the ceria–zirconia catalyst resulted in the adsorbate disproportionation or coupling, depending on the sample composition. [Copyright &y& Elsevier]

Abstract: FTIR study of iron and aluminium forms of zeolite MCM-58 showed that location of heteroatoms in this IFR structure depends on the type of heteroatom. The combination of the pyridine and CO adsorption allowed determination of the concentration of hydroxyls in the 12- and 5/6-rings. Both Fe and Al are generating hydroxyls pointing towards either 12-ring or 5/6-rings but the former are located in positions giving Si–OH–Fe hydroxyls pointing mainly to the 12-rings while the latter gives rise to the Si–OH–Al groups pointing primarily to the narrower 5- and 6-rings. (Al)MCM-58 undergoes only minor dehydroxylation associated with the acid sites even at temperatures as high as 700°C, which indicates unique stabilization of Al atoms in the IFR structure. In the case of (Fe)MCM-58, dehydroxylation is more extensive. Furthermore the OH located in the 5/6-rings dehydroxylate at lower temperatures than those in the 12-rings. The study also demonstrates that the concentration of the framework and extraframework iron atoms can be determined by a simple method based on pyridine adsorption followed by IR spectroscopy. [Copyright &y& Elsevier]

• Effect of Zr, V, Mo and W-doping of K-OMS-2 in soot combustion was elucidated. • Importance of doping via impregnation or coprecipitation was established. • Catalytic performance was evaluated in the presence of NO and SO 2. • Work function was found as a concise descriptor of catalyst behavior. Two series of cryptomelane doped with d0 ions (Zr4+, V5+, Mo6+, W6+) were synthesized by impregnation and coprecipitation methods. The obtained samples were characterized in detail by XRD, RS, TEM/EDX, XRF, XPS, O 2 -TPD and by the work function measurements. Catalytic tests were performed in tight and loose contacts using various reaction mixtures (O 2 , O 2 + NO, O 2 + NO + SO 2). The role of dopants was examined and discussed in terms of their influence on the principal catalysts' functionalities such as catalytic performance, structural and thermal stability and resistance to SO 2. The work function was found to be a prime descriptor used for the explanation of the catalytic performance in soot oxidation, taking into account the nature of dopants, the way they were introduced, and the composition of the reaction mixture. Due to the formation of a hot ring at the catalyst-soot interface, the oxidation of soot and NO are coupled and significantly influenced by the presence of SO 2. It was found that the catalytic activity of the impregnated samples results from the opposite effects of the work function on soot combustion in NO and on sulfur poisoning of the beneficial NO to NO 2 oxidation. It leads to an optimal work function value of 4.04 eV observed for the W-doped catalyst. For the coprecipitated samples, due to the non-monotonous and opposite character of those processes, the effect of doping on the cryptomelane catalytic performance in the presence of SO 2 is smeared out. [ABSTRACT FROM AUTHOR]

Abstract: Vermiculite was treated with 0.8M solutions of hydrochloric and sulphuric acids for 2, 8, and 24h. The obtained materials were characterized with respect to their composition (XRF), structure (XRD, FTIR, UV–vis-DRS), texture (BET), surface acidity (NH3-TPD) and catalytic properties. Modification of vermiculite with acids significantly increased its surface area and pore volume and led to partial leaching of iron, aluminium and magnesium ions from its octahedral sheets. Efficiency of the leaching process depended on its duration and the nature of acid used. Acid treatment strongly modified the vermiculite structure leading to a distinct increase of its catalytic activity in the selective catalytic reduction of nitric oxide (SCR NO) process. In a series of the studied samples the best catalytic performance was found for vermiculite treated with sulphuric acid for 8h. [Copyright &y& Elsevier]