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The gas‐phase oxidation of acrolein to acrylic acid on a hydrothermally prepared mixed oxide catalyst was investigated by steady‐state isotopic transient kinetic analysis (SSIKTA) as well as different types of concentration‐programmed techniques (CPR‐pulse, CPO) under in situ or process‐relevant conditions. Balancing the amounts of active oxygen gives an overview of the quantities of participating bulk oxygen species. The dynamics of bulk oxygen lead to re‐oxidation processes on the catalyst surface and thus influence the selectivity pattern of the network of acrolein oxidation. Furthermore, the bulk dynamics are activated by temperature.

Dedicated to Professor Rüdiger Lange on the occasion of his 65th birthdayOxidation of acrolein to acrylic acid on a Mo/V/W mixed oxide catalyst was studied by transient (cyclic temperature-programmed (TP)) as well as steady-state methods. TP reactions (TPReactions) exhibit an activity hysteresis of the catalyst with respect to temperature. As a result of the steady-state measurements, the activity hysteresis is not related to multiple steady states and is exclusively a transient phenomenon. Generally, the dynamics of bulk oxygen plays a key role leading to a reversible oxidation/reduction of the catalyst surface which influences the activity. This means the bulk acts as oxygen buffer. In this context, a reaction model, which involves the participation of bulk oxygen, was deduced and verified by modeling.

SummaryPolycrystalline CuInSe2 (CISe) nanorods are promising for the fabrication of highly efficient active layers in solar cells. In this work we report on a nanocasting approach, which uses track-etched polycarbonate films as hard templates for obtaining three-dimensionally (3D) arranged CISe nanorod arrays. Copper and indium ketoacidoximato complexes and selenourea were employed as molecular precursors. Arrays of parallel isolated cylindrical pores of 100 nm nominal diameter and 5 μm length were used for the infiltration of the precursor solution under inert atmosphere, followed by drying, thermal conversion into a preceramic ‘green body’, a subsequent dissolution of the template, and a final thermal treatment at 450 °C. The nanorods that where synthesised in this way have dimensions equal to the pore sizes of the template. Investigation of the CuInSe2 nanorod samples by spectroscopic and diffraction methods confirmed a high purity and crystallinity, and a stoichiometric composition of the CISe ternary semiconductor compound.

The activity of Mo/V/W mixed oxide catalyst in the gas phase oxidation of acrolein to acrylic acid is tremendously influenced by addition of fed water. This effect of water is investigated and connected to the catalytic mechanism by several stationary kinetic measurements and transient response methods, such as temperature‐programmed reduction, oxidation and desorption experiments, special concentration‐programmed methods as well as H218O‐SSITKA and D2O‐SSITKA experiments. Furthermore, kinetic modeling, based on results of H218O‐SSITKA experiments in a wide temperature and feed water content range gives access to kinetic parameters of single reaction steps in the catalytic mechanism. The developed mechanism is not only able to describe conversion and selectivities, inclusively the effect of water, but also describes the 18O‐degree of labeling of all reaction components quantitatively.