AQura GmbH

Hanau am Main, Germany

AQura GmbH

Hanau am Main, Germany
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Mobus K.,Evonik Industries | Grunewald E.,Evonik Industries | Wieland S.D.,Evonik Industries | Parker S.F.,Rutherford Appleton Laboratory | Albers P.W.,AQura GmbH
Journal of Catalysis | Year: 2014

The influence of alloying supported palladium particles of 2 nm size with platinum and iron on the catalytic activity for the selective hydrogenation of nitrobenzene (NB) was studied. We show that the use of a carbon black support of enhanced sp2 character has a marked 'templating' effect on the location of the palladium particles, which are preferentially deposited at the edge sites of the carbon support surface. Alloying with platinum and iron leads to disaggregation down to isolated primary particles, and this has a major effect on the catalytic activity (Pd 6.6, PdPt 36.9, PdPtFe 23.1 mmol NB min-1), as well as on the relative amounts of β-palladium hydride formed (normalized peak integrals: Pd 127.0, PdPt 87.6, PdPtFe 27.2). The results enable a greater understanding of how better performance can be obtained in catalysts by appropriate choice of support, particle size, alloying and adjustment of hydrogen storage capability. © 2013 Elsevier Inc. All rights reserved.

Albers P.W.,AQura GmbH | Mobus K.,Evonik Industries | Frost C.D.,Rutherford Appleton Laboratory | Parker S.F.,Rutherford Appleton Laboratory
Journal of Physical Chemistry C | Year: 2011

The proton dynamics of palladium catalysts on activated carbon, of palladium on calcium carbonate, and of lead-modified palladium on calcium carbonate (the Lindlar-catalyst), hydrogenated in situ to comparable equilibrium pressure, were measured by means of inelastic incoherent neutron scattering. Isolated primary particles of palladium of ~3.2 nm size showed a lower degree of formation of β-phase hydride than 10-15 nm sized aggregates, which were formed from ~3.7 nm primary particles of palladium. The addition of lead to the palladium on calcium carbonate in catalysts of identical primary particle size (3.7 nm) and shape caused a decrease in the β-phase hydride formation by a factor of 2. For the catalyst selectivity in the hydrogenation of triple to double bonds not only the presence of modifiers at the surface but also a reduced, moderated hydrogen storage function is of relevance. © 2011 American Chemical Society.

Franke R.,Evonik Industries | Franke R.,Ruhr University Bochum | Hannebauer B.,AQura GmbH
Physical Chemistry Chemical Physics | Year: 2011

This paper examines how the accuracy of activity coefficients at infinite dilution calculated from the conductor-like screening model for real solvents (COSMO-RS) depends on the basis set and the quantum chemical method used. Activity coefficients at various temperatures serve as experimental parameters for optimising the COSMO-RS parameters. A modification of the electrostatic misfit term of the energy function of COSMO-RS is presented that leads to a slightly higher accuracy. COSMO-RS parameter sets for nine different systematically varied basis sets using the density functional theory with the BP86 functional show that at least a valence double-zeta basis set is necessary for good accuracy. Larger basis sets show no advantages. Investigations of eight different quantum chemical calculation methods using a valence triple-zeta basis set are documented. Hartree-Fock and local density approximations give relatively poor results. The gradient-corrected density functionals investigated and the B3LYP hybrid functional show practically identical accuracy. The most accurate parameterisation was obtained with MP2. © 2011 the Owner Societies.

Parker S.F.,Rutherford Appleton Laboratory | Lennon D.,University of Glasgow | Albers P.W.,AQura GmbH
Applied Spectroscopy | Year: 2011

Inelastic neutron scattering spectroscopy (INS) has enabled vibrational spectra to be measured for over 50 years. Most studies have used a type of spectrometer that is straightforward to build and use and that provides spectra that are not dissimilar to infrared and Raman spectra. In this Focal Point Review Article we show the advantages of a type of neutron vibrational spectrometer that has been largely unknown to the spectroscopy community. These instruments are able to access regions of low momentum transfer at relatively large energy transfer. This means that the C-H, N-H, and O-H stretch regions can be exploited by INS spectroscopy for the first time. The instruments generally have very large detector area, which means that they are significantly more sensitive than the more commonly used instruments. They also allow the energy transfer as a function of momentum transfer to be examined. After briefly outlining the basics of INS spectroscopy, we describe the operational principles of the instruments and show how flux and resolution can be traded. We then review how the advantages of the instruments can be used to gain understanding of molecular systems in areas as diverse as hydrogen storage, hydrogen bonding, and fullerenes. The instruments are starting to have a significant impact in studies of catalysts and this is illustrated with recent studies of hydrogen on fuel cell catalystsmethyl chloride synthesis, the deactivation of methane reforming catalysts, and a model carbon monoxide oxidation catalyst. © 2011 Society for Applied Spectroscopy.

Franke R.,Evonik Industries | Hannebauer B.,AQura GmbH | Jung S.,Evonik Industries
Chemical Engineering and Technology | Year: 2010

Gas solubilities belong to the class of property data that form the basis for a large number of technological applications. For example, they represent the property data basis for absorption processes and are important in the design of gas-liquid reactors. In this paper, we determine Henry coefficients as a measure of gas solubility by means of a series of computational approaches used in industrial practice, and we compare the results to experimentally determined values. Temperature-varied values for hydrocarbon-alcohol systems constitute the object of the study. Of the methods employed, PSRK, UNIFAC(Do) and COSMO-RS display the highest predictive capability. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Parker S.F.,Rutherford Appleton Laboratory | Refson K.,Rutherford Appleton Laboratory | Hannon A.C.,Rutherford Appleton Laboratory | Barney E.R.,Rutherford Appleton Laboratory | And 2 more authors.
Journal of Physical Chemistry C | Year: 2010

The structure of hydrous palladium oxide has been investigated by powder diffraction with both X-rays and neutrons, transmission electron microscopy, inelastic neutron scattering spectroscopy, infrared spectroscopy, and periodic-DFT calculations. The results clearly show the formulation as PdO·H2O is correct rather than as Pd(OH)2 as has been proposed previously. The material is best described as ∼18 Å diameter particles of nanocrystalline PdO with a monolayer or so of hydroxyls capped by 4-7 layers of water. The very small nanocrystallites are agglomerated into larger clusters which reduces the effective surface area. This structure is very similar to that proposed for hydrous ruthenium oxide, RuO 2·xH2O, x = 2, and for water on anatase and rutile. This model provides a quantitative explanation for why hydrous palladium oxide deactivates three times faster at 25 °C than at 100 °C in the low-temperature oxidation of CO to CO2. © 2010 American Chemical Society.

Baumann A.,University of Munster | Baumann A.,AQura GmbH | Pfeifer T.,University of Munster | Pfeifer T.,Volkswagen AG | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2013

Melarsoprol is the only currently available drug for treatment of the late stage of African trypanosomiasis (sleeping sickness). Unfortunately, the arsenic-containing drug causes serious side effects, for which the mechanisms have not been elucidated so far. This investigation describes the study of the melarsoprol biotransformation processes by electrochemical (EC) techniques. Based on EC, potential oxidation reactions of melarsoprol are examined. Moreover, the reactivity of melarsoprol, its metabolite melarsen oxide, and their oxidation products toward the tripeptide glutathione and the proteins hemoglobin and human serum albumin is evaluated. The combination of different analytical techniques allows the identification as well as the quantification of the biotransformation products. The hyphenation of liquid chromatography (LC) and electrospray ionization mass spectrometry (ESI-MS) is applied for identification and structure elucidation, which implies the determination of exact masses and fragmentation patterns. For the selective detection of arsenic containing metabolites, LC coupled to inductively coupled plasma mass spectrometry is utilized. Based on the obtained data, the oxidative biotransformation of melarsoprol can be predicted, revealing novel species which have been suspected, but not been identified up to now. The results of the protein studies prove that melarsen oxide, the active derivative of melarsoprol, strongly binds to human hemoglobin and forms different adducts via the free cysteinyl groups of the hemoglobin α- and β-chain. © 2013 Springer-Verlag Berlin Heidelberg.

Mushtaq S.,London Metropolitan University | Steers E.B.M.,London Metropolitan University | Pickering J.C.,Imperial College London | Smid P.,AQura GmbH
Journal of Analytical Atomic Spectrometry | Year: 2014

Small amounts of hydrogen or oxygen in either argon or neon plasmas cause previously unexplained enhanced excitation of various analyte atomic lines with upper energies close to 5 eV. We suggest this enhancement is due to three body collisions involving two hydrogen or oxygen atoms and a sample atom. © the Partner Organisations 2014.

A novel approach for post-digestion stabilisation of osmium was developed and evaluated as a proof of concept during this study. Regulatory requirements for the testing of Os contents in pharmaceutical products are now included in the new general USP chapters 〈232〉 and 〈233〉, as well as in EP chapters 5.20 and 2.4.20. A new ICH guideline for elemental impurities Q3D is in preparation. Therefore, trace elemental analysis of Os will be required for release testing of pharmaceutical substances and final products in the near future. In this study Os determination was performed by inductively coupled plasma mass spectrometry (ICP-MS) after nitric acid pressure vessel digestion. Since osmium in an oxidising and acidic environment readily forms volatile species, there is a need for osmium stabilization to prevent the loss of these fractions or to prevent overestimation due to vapour enrichment in spray chambers used on ICP instruments. Pressure vessel digestion with nitric acid is a universal mineralisation method for organic compounds in order to determine trace elemental concentrations and will be required to meet the new pharmacopeial regulations. Therefore, it is in principle possible to cover the whole list of required elements in USP 〈232〉 to be tested in one digestion run, now including osmium, since an aliquot of the digestion solution is stabilised using the presented stabilisation solution whereas the rest of the digestion solution can be used for the determination of the other required trace element contents. In this study we demonstrated the suitability of thiourea as a complexing agent for osmium. Already millimolar quantities of thiourea in combination with ascorbic acid in acidic media allowed the stabilization of μg L-1 quantities of osmium in solution following high-pressure digestion. To meet method validation requirements, a spike recovery experiment with real world samples, the pharmaceutical excipient Avicel, was performed to evaluate this type of stabilization in combination with high-pressure digestion with concentrated nitric acid. First proof of concept experiments showed average recoveries of 81% for samples spiked with 1.0 μg g-1 osmium and a precision of 7% for six-fold preparation and measurement. Additional experiments showed that matrix-matched calibrations may be mandatory for reliable determination of osmium contents. This journal is © The Royal Society of Chemistry.

Franke R.,Evonik Industries | Franke R.,Ruhr University Bochum | Hannebauer B.,AQura GmbH | Jung S.,TU Dortmund
Fluid Phase Equilibria | Year: 2013

The COSMO-RS method allows mixed-phase thermodynamic parameters to be calculated from quantum-chemically determined surface screening charge-density distributions. For this method we shall present and discuss a parameterization for alkanes and olefins in alcohols, which are important classes of molecules in industrial application. As we were able to demonstrate, the accuracy of predicting from a specialized parameterization can be significantly better than that from a universal parameterization. Furthermore, we critically compared the method with the UNIFAC(Do) group contribution method. © 2012 Elsevier B.V..

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