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Homogeneous dispersions and small size of deposited high-content cobalt on alumina were achieved by the co-precipitation method and were well maintained on the cobalt-based binary alumina catalysts with Zn, Ag, Fe, Cu or Ni as modifiers. The component and concentration of deposited cobalt species were characterized by UV–vis, EDX and XPS spectra and found to be greatly related to the Co loading, calcination temperatures and the type of additive metals. The optimal Co loading of 8 wt% and calcination temperatures of 800 °C were demonstrated. With respect to the single cobalt-based alumina catalyst, the surface concentration of Co 2+ on the binary catalysts with addition of Fe, Cu, Ag or Ni was all reduced and accompanying with part conversion of Co 2+ to Co 3 O 4 on the Fe and Ni-modified catalysts. A slight enhanced surface Co 2+ concentration was only achieved on the Zn-promoted catalyst. It was also demonstrated that for the case of Cu and Fe the additive metals themselves participated in the activation of propene. The octahedral and tetrahedral Co 2+ ions were suggested as the common active sites. A maximum deNOx activity of 96% was observed on the 8Co4ZnA800 catalyst at the reaction temperatures of 450 °C, and the catalytic performance on the cobalt-based binary alumina catalysts can be described as fellows: CoZn > CoAg, CoNi > Co Cu > CoFe. Based on the in situ DRIFT spectra, different reaction intermediates R–ONO and –NCO besides –NO 2 were formed on the 8Co4ZnA800 and 8Co4FeA800 samples, respectively, demonstrating their dissimilar reaction mechanisms.

Incipient wetness impregnation of zeolite Y with copper(II) nitrate solution and inert activation at 650 °C led to active catalysts for the oxidative carbonylation of methanol to dimethyl carbonate in the gas phase. Activities were measured under elevated pressure (0.4–1.6 MPa) with feed compositions of CO/MeOH/O 2 = 40/20/6–1.5 vol.% (balanced by N 2 ) over zeolite Y loaded with 10–17 wt.% copper. It could be shown that inert activation at 650 °C enhanced the activity, and that Cu loading of 14–17 wt.% gave the best performance. By combined XRD, TEM, TPR and DRIFT characterization it was found that the inert activation initiated dispersion of crystalline CuO, auto-reduction of Cu 2+ to Cu + and redistribution of copper ions with enrichment inside the supercages of the zeolite. The O 2 content of the feed was found to control the selectivity to dimethyl carbonate. Dimethyl carbonate selectivities of 70–75% were achieved within the temperature range of 140–170 °C at an O 2 content of 1.5 vol.%. This allowed space-time yields of dimethyl carbonate up to 632 g l cat −1 h −1 at methanol conversions of 5–12%. Formation of the main side product, dimethoxymethane, was surprisingly affected by CO, which is not in line with suggested reaction pathways. A mechanism is proposed including formation of surface carbonate structures as common intermediate.

Different sulphur trap materials based on mesoporous Al2O3 supports modified with the storage component Ca or Ba and the oxidation components Pt or Cu or Mn were prepared and the SO2 uptake behaviour examined in the temperature range 50–600 °C. A comparison between the different oxidation components shows that the presence of Pt is not a necessary precondition for attaining a good storage behaviour under these test conditions. Mn is the most suitable oxidation component. Tests performed over four temperature cycles show that the removal efficiency for SO2 gradually decreases over the course of temperature cycles. Moreover, a progressive diminution of the SO2 uptake is observed especially in the lower temperature range during the temperature cycles. A further modification with Na prevents this drawback. Especially a distinct improvement is observed with the Ca-containing material. It stored 22 wt.% sulphate during the four temperature cycles. This material is regarded as being most suitable for application as sulphur trap material.

The interaction of DeNOx components comprising NO, NO2, propane, O2 and H2 with a selected Ag/Al2O3 catalyst was studied by in situ FTIR spectroscopy at a fixed temperature where a promoting effect of H2 admixture on the catalytic NOx reduction has been reported to occur. The significant enhancement of nitrato and acetate ad-species from NO and propane, respectively, could be confirmed. New findings are the relative inertness of these species for further reaction progress. Instead, nitrite, nitrito, and nitro species are reactive, and the H2 co-fed favours the formation of those species. Nevertheless, the way H2 interferes with the kind of species formed includes the promotion of oxidative reaction steps evidenced by different effect of H2 on the interaction of the catalyst with NO/O2 and NO2, respectively. During NO2/H2 adsorption adsorbed NOx species and Ag+ ions at the surface are reduced. This prevents abundant formation of stable nitrato species and favour the formation of largely unstable but reactive nitro and nitrito species. Otherwise, NO2 is able to oxidize pre-reduced Ag/Al2O3. Furthermore, indications were found for minor propene formation from propane in the presence of hydrogen.

The potential of zeolites MFI and MOR promoted by In and Ce as catalysts for the SCR of NOx by methane and propane was studied, particularly considering their stability in the presence of water vapour. A preparation route for a zeolite-based Ce/In composite catalyst was developed and the influence of several reaction conditions was studied to optimise the catalyst performance. TPR and FTIRS were used to check the preparation steps and to investigate the catalyst structure. These data were used together with results from characterisation by X-ray-based techniques to describe the generation and catalytic function of different indium species ((InO)+, In2O3 cluster) and their co-operation with ceria in the composite catalyst. The primary role of the CeOx promoter is to catalyse the oxidation of NO to NO2. Probably, NO2 reacts with methane on Lewis-acidic and redoxactive (InO)+ species, but the further reaction of the intermediate formed needs the presence of residual Bronsted-acid sites. SCR of NOx by methane or propane is still partially inhibited by adsorption competition between water and the hydrocarbons on the (InO)+ species. Higher SCR activity could be achieved by increased hydrocarbon partial pressure in the feed, shifting presumably the competitive adsorption to enhanced adsorption of methane and propane, respectively. Furthermore, combining of methane and propane as reductants opens an opportunity to broaden the ‘temperature window’ for the SCR of NOx. Different influence of hydrothermal ageing was obtained with methane and propane, respectively, as reducing agent.

The NO, NO/O2, and NO/O2/H2O adsorption on MnO2/NaY (5 and 15 wt.% MnO2) composite catalyst and NaY has been studied by means of in situ FTIR and EPR spectroscopy at elevated temperatures and during heating under reaction-like conditions. NO adsorption and co-adsorption of NO and O2 on NaY and MnO2/NaY proceeds via oxidation of NO forming NO2− and NO3− species. Whereas the manganese dioxide preferably acts as oxidising agent, the zeolite stores the NOx species as nitrite and nitrate ions in the solid. In the presence of oxygen, the nitrate formation is enhanced due to additional oxidation of NO through gaseous oxygen leading to NO2. Dimerisation of NO2 to N2O4 and following disproportionation of the latter causes the formation of NO+ and NO3− species which are associated with nucleophilic zeolitic oxygen and especially alkali cations of the zeolite, respectively. The presence of oxygen facilitates reoxidation of Mn2+ which keeps more Mn ions in the active state. Pre-adsorbed water and higher amounts of water vapour in the feed hinder the NO adsorption by blocking the adsorption sites and shift the nitrate formation to higher temperatures. The quantities and thermal stability of the nitrates formed during NO and NO/O2 adsorption differs which points to a different mechanism of nitrate formation. In the absence of gaseous oxygen, nitrates are formed by participation of only lattice oxygen. In the presence of oxygen, nitrate formation by dimerisation and disproportionation reactions of NO2 dominates. The manganese component of the composite catalyst supports the oxidation of NO to nitrite and subsequently to nitrate. During this process Mn4+ is reduced to Mn2+ as evidenced by in situ EPR measurements.