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Bifunctional catalysts consisting of copper, zinc oxide, and γ -alumina have been produced by means of extrusion. The effects of formulation and forming conditions on morphology, pore texture, and copper surface area are discussed. These extruded catalysts have been employed in the fixed-bed gas-phase conversion of dimethyl maleate at temperatures between 453 and 493 K and space velocities ranging from 0.2 to 2.4 h −1 . Copper catalyzes the hydrogenation and hydrogenolysis reactions yielding γ -butyrolactone, and 1,4-butanediol. γ -Alumina provides weakly acidic sites which promote the subsequent dehydration of 1,4-butanediol to tetrahydrofuran. Coupled products are methanol and water. Through choice of composition and pore texture of the extrudates it is possible to achieve tetrahydrofuran yields of 100% (basis the C 4 -products) at a low pressure (2.5 MPa) in a single stage.

in Wiley InterScience (www.interscience.wiley.com).The particle formation process during the precipitation of barium sulfate from aqueous solutions of barium chloride and sodium sulfate was studied experimentally and numerically. Particle formation was examined offline and in situ on timescales ranging from 55 ms to 1 s. Precipitation experiments were performed in a tubular reactor of adjustable length equipped with a flow-through cuvette. The mass fraction of the crystalline precipitate was followed time-resolved using wide-angle X-ray scattering (WAXS), performed at the synchrotron radiation facility ANKA of FZK Karlsruhe GmbH. A high degree of correspondence between numerical and experimental results was achieved using nucleation kinetics based on experimental findings in combination with diffusion-controlled growth kinetics in the population balance equation. Furthermore, the online measurements showed that the lattice ion ratio (educt ratio) has no influence on nucleation kinetics, which means that the adsorption of lattice ions on pre-nuclei has no influence on their respective interfacial energy.

An den exemplarischen schwerlöslichen Stoffsystemen Barium-und Strontiumsulfat wird der Einfluss der Prozessparameter Übersättigung und freies Gitterionenverhältnis auf das resultierende Fällungsprodukt untersucht. Durch Variation der Übersättigung als thermodynamische Triebkraft für Kristallisationsprozesse kann gezielt Einfluss auf die Partikelgrößenverteilung des gefällten Endproduktes genommen werden.

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