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Address: Chair in Catalysis and Chemical Engineering, Department of Chemical and Biochemical Engineering, Danish Technical University (DTU), DK-2800 Kgs. Lyngby / Copenhagen, Denmark, jdg(at)kt.dtu.dk; tel.: +45-45 25 28 38; Homepage at DTU
Novel preparation methods to new nanomaterials, efficient catalytic tests and proper catalyst characterization are our basis for the design of new catalysts. Presently applied synthesis strategies are: flame synthesis, preparation of size-controlled particles, and synthesis in supercritical fluids.
Supercritical fluids offer intesting properties for reaction design: tunability of density, gas-like transport properties and more liquid-like solvent properties. Carbon dioxide is particularly intesting since the pressure and temperature required are moderate (Tc=31°C, pC=73.75 bar). Both hydrogenation and oxidation reactions are of interest. Moreover, the use of carbon dioxide as a safer and cheaper C1-building block than carbon monoxide or phosgene is a great chalenge in "green chemistry". Here, carbon dioxide can act both as reactant and solvent and thus leads to a solvent-less process.
The conversion of biomass platform molecules, e.g. fructose/glucose and glycerol, into transportable fuels is very attractive. Mostly dehydration and hydrogenation steps and in case of glycerol also aldol condensation are required. One of the interesting products is 2,5-dimethylfuran, which can be derived using an acid catalysis for dehydration and alloy catalysts for hydrogenation and appears an attractive starting point for deriving fuels from biointermediates. Efficient catalyst screening together with rational design of alloy catalysts and reaction engineering aspects appear important to tackle this subject.
Gold catalysts have recently received strong interest. Although bulk gold is not catalytically active, small gold particles have shown interesting activity, i.e. in the oxidation of CO at low temperatures, in the epoxidation of propylene or in the oxidation of alcohols.
For the new generation of lean-burn engines, which offer the possibility for lower fuel consumption, the calssical 3-way catalyst cannot be applied (NOx is not removed effectively). A new catalyst concept is needed. One possibility is the class of NOx-storage catalysts. It stores NOx under the usual lean fuel conditions, but can be rapidly regenerated during a puls of fuel-rich conditions.
X-ray diffraction, extended X-ray absorption spectroscopy, Raman and IR spectroscopy and eare - among other techniques - versatile and powerful tools for the investigation of heterogeneous catalysts under reaction conditions. The techniques can be applied in gaseous phase but also in liquid phase and at high pressure.
Tomography
Time resolved studies in the second scale
Combination of EXAFS and XRD
Fluorescence EXAFS
In situ EXAFS in supercritical fluids at 200 bar
Some interesting Links for EXAFS