Solvent-modified supercritical CO: A beneficial medium for heterogeneously catalyzed oxidation reactions

Caravati, Matteo; Grunwaldt, Jan‐Dierk; Baiker, Alfons

doi:10.1016/j.apcata.2005.09.037

Cited by 39 publications

(22 citation statements)

References 29 publications

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“…Especially for oxidations, scCO 2 can offer many advantages such as: (i) dilution of the reaction medium by inert CO 2 , leading to inherently safer process conditions, (ii) elimination of gas-liquid mass transfer problems, and enhancement of fluid-solid transport [125][126][127][128][129][130]. Nevertheless, a disadvantage is the rather low throughput per volume, due to the dilution of the substrate with CO 2 .…”

Section: Engineering Principlesmentioning

confidence: 99%

Selective Oxidation Catalysis: Opportunities and Challenges

et al. 2009

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This contribution discusses some aspects crucial for designing optimal and sustainable oxidation processes. The catalyst, although at the heart of the system, is only one decisive design parameter amongst many others. Indeed, an interdisciplinary approach is required to improve existing processes, but also to rationally and systematically access opportunities for oxidation research on renewable feedstock compounds.

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Section: Engineering Principlesmentioning

confidence: 99%

Selective Oxidation Catalysis: Opportunities and Challenges

et al. 2009

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“…By adjusting pressure and temperature the solvent and reactants can be assembled in a single reaction phase. Besides, the reaction can be performed in a CO 2 -expanded reaction phase, where the oxygen solubility and the mass transport properties are still high [28,29]. In the present study we thus investigated the combination of these two concepts-gold catalyst and dense CO 2 .…”

Section: Introductionmentioning

confidence: 96%

Gold catalysed selective oxidation of alcohols in supercritical carbon dioxide

2007

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The oxidation of benzyl alcohol to benzaldehyde over different supported gold catalysts in supercritical carbon dioxide has been investigated in a high-pressure batch reactor. Only molecular oxygen was used as oxidant and no base was needed. Different supports and preparation methods for the catalysts were tested and parameters like reaction temperature, pressure and molar ratios of the components were varied to study the catalytic behaviour. Gold colloids deposited on a titania support (1%Au/TiO 2 ) yielded a conversion of 16.0% after 3 h and a high selectivity to benzaldehyde of 99% under single-phase conditions. The reaction rate was significantly higher than in a corresponding ''solvent-free'' reaction without CO 2 . Even higher rates were found when a CO 2 -expanded phase was present. Monitoring of the oxidation in a high-pressure view cell via infrared transmission spectroscopy unravelled a slowdown of the reaction rate above 15% conversion. In addition, 1-octanol and geraniol were oxidised as well under similar conditions, yielding conversions of 4% and 10%, respectively, with selectivities towards octanal and geranial of 90% and 30%. Thus, the combined application of gold-based catalysts and supercritical CO 2 offers an interesting alternative to the known methods of alcohol oxidation.

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“…The complete range from pure supercritical CO 2 to toluene modified CO 2 to CO 2 expanded toluene to pure toluene was studied. Here, the highest reaction rate was found in the single-phase range (mixture of educt and product) with toluene modified CO 2 [118].…”

Section: Oxidations (For Surveys See [19 92-96])mentioning

confidence: 84%

Heterogeneous Catalysis in Supercritical Media: 1. Carbon Dioxide

Kruse

Vogel

2007

Chem Eng & Technol

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Dedicated to Prof. Dr.-Ing. Jens Weitkamp on the occasion of his 65th birthdayOver the past few years, supercritical fluids have received considerable interest as reaction media. Supercritical fluids combine properties of gases and liquids. Densities are lower than in the liquid phase, but significantly higher than in the gas phase. This makes supercritical fluids excellent solvents for a variety of substances. The good dissolution capacity exists only in or near the supercritical range. Reaction products can be separated, for instance, simply by decreasing temperature and pressure. This may be used to intensify the process as complex separation processes, like distillation, are avoided.

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Solvent-modified supercritical CO: A beneficial medium for heterogeneously catalyzed oxidation reactions

Cited by 39 publications

References 29 publications

Selective Oxidation Catalysis: Opportunities and Challenges

Selective Oxidation Catalysis: Opportunities and Challenges

Gold catalysed selective oxidation of alcohols in supercritical carbon dioxide

Heterogeneous Catalysis in Supercritical Media: 1. Carbon Dioxide

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