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Abstract: The role of extra-framework and framework aluminium in wet-ion exchanged Fe-ZSM5 has been studied using 29Si NMR and 27Al triple quantum magic angle spinning (3QMAS) NMR. A series of samples were studied, the parent material, the wet ion exchanged Fe-ZSM5 and Fe-ZSM5 that has been used in the decomposition of N2O with varying reaction conditions. Various framework and extra-framework aluminium species have been identified. It was found that cationic Fe species prefer to replace the Brønsted acid protons in their charge balancing role at those aluminium sites associated with the largest quadrupolar product. The framework aluminium atoms that pertain to the smaller quadrupolar product, which are either charge balanced by extra-framework aluminium or a proton, are much less prone to exchange. In the catalytic decomposition of N2O it seemed that water present in small amounts enhances the catalytic activity. However, water also decreases the long term stability and performance by dealuminating the zeolite framework. With a high amount of water present, Fe-ZSM5 was destabilised and catalytically inferior. [Copyright &y& Elsevier]

Abstract: Hydrogen membrane reactors are an advanced technology for pre-combustion CO2 capture at gas fired power stations. Developments in the field of membrane manufacturing, bench scale testing, module modeling and technoeconomic evaluations are discussed. Semi-commercial modules with membranes up to 50 cm length are currently available. A bench scale multi-tube membrane reactor with a capacity up to 8 parallel tubes has been successfully operated for separation, membrane water-gas shift and membrane reforming experiments. A membrane module model has been developed that is a key element in the scale-up of membrane reactors. Techno-economic evaluation of membrane reactors indicates that for CO2 capture at gas fired power plants membrane water-gas shift has a better potential than membrane reforming and than conventional pre-combustion CO2 capturing using Selexol. [Copyright &y& Elsevier]

Abstract: Conversion of NO x with reducing agents H2, CO and CH4, with and without O2, H2O, and CO2 were studied with catalysts based on MOR zeolite loaded with palladium and cerium. The catalysts reached high NO x to N2 conversion with H2 and CO (>90% conversion and N2 selectivity) range under lean conditions. The formation of N2O is absent in the presence of both H2 and CO together with oxygen in the feed, which will be the case in lean engine exhaust. PdMOR shows synergic co-operation between H2 and CO at 450–500K. The positive effect of cerium is significant in the case of H2 and CH4 reducing agent but is less obvious with H2/CO mixture and under lean conditions. Cerium lowers the reducibility of Pd species in the zeolite micropores. The catalysts showed excellent stability at temperatures up to 673K in a feed with 2500ppm CH4, 500ppm NO, 5% O2, 10% H2O (0–1% H2), N2 balance but deactivation is noticed at higher temperatures. Combining results of the present study with those of previous studies it shows that the PdMOR-based catalysts are good catalysts for NO x reduction with H2, CO, hydrocarbons, alcohols and aldehydes under lean conditions at temperatures up to 673K. [Copyright &y& Elsevier]

Abstract: The hydrothermal stability of WIE-based Fe-ZSM-5 and Fe-BEA for N2O decomposition in the presence of NO, H2O and O2 was studied at 723K. Catalysts were characterized with UV–vis, IR and Al-XANES. The N2O conversion remains at a constant level with Fe–H-BEA even in the presence of large amounts of H2O. Deactivation was, however, observed with Fe–H-ZSM-5 already in the presence of 0.5vol.% water. The analysis of deactivated samples indicated that steam-dealumination and clustering of iron occurred during the reaction with Fe-ZSM-5. Replacement of protons for sodium in Fe-ZSM-5 slowed down the rate of catalyst deactivation significantly. Steam-dealumination is likely to precede the clustering of iron in Fe–H-ZSM-5. The excellent hydrothermal stability of WIE-based Fe–H-BEA relates to the high initial degree of dealumination in the as-received BEA. [Copyright &y& Elsevier]

Abstract: NO-assisted N2O decomposition over four different Fe-ZSM-5 samples prepared by wet ion exchange (WIE) or chemical vapor deposition (CVD) of FeCl3 was investigated by steady-state kinetics, in situ infrared (IR) spectroscopy, and transient response methods. Despite their lower iron loading, the samples prepared by WIE had the highest activity for N2O decomposition in the presence of NO. The in situ IR experiments showed that the most active sample was characterized by a high concentration of adsorbed NO, as well as adsorbed NO2 under reaction conditions. Step response experiments proved that NO2 is an intermediate of the catalytic cycle and functions as intermediate oxygen storage. IR and transient kinetic experiments showed that WIE catalysts behave qualitatively different in NO-assisted N2O decomposition than CVD catalysts. These differences are discussed in terms of the different structure of the iron species in the two types of samples. [Copyright &y& Elsevier]

Abstract: Fe-FER is an active catalyst for the abatement of N2O in the tail gas of nitric acid plants. The activity of Fe-FER can be increased if Ru is added as a second active component. This is a surprising finding, because noble metals are usually strongly inhibited by NO, which is always present in tail gas. Yet the bimetallic FeRu-FER catalyst is more active than the sum of the components, Fe-FER and Ru-FER. A synergy between Fe and Ru can explain this phenomenon. This work discusses the role of Fe and Ru in the reaction mechanism as well as the interplay of these two components. In situ IR measurements show that the preferential adsorption of NO and its reaction products on Fe in the bimetallic catalyst reduces the inhibiting effect of NO on the Ru component; this effect largely contributes to the synergy between Fe and Ru. Moreover, in situ X-ray absorption data are presented, which allow for tracing the average oxidation state of the two active components Fe and Ru under reaction conditions. [Copyright &y& Elsevier]