Publications by authors named "Marco Haumann"

13 Publications

  • Page 1 of 1

Capturing spatially resolved kinetic data and coking of Ga-Pt supported catalytically active liquid metal solutions during propane dehydrogenation .

Faraday Discuss 2021 Mar 5. Epub 2021 Mar 5.

Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Lehrstuhl für Chemische Reaktionstechnik (CRT), Egerlandstr. 3, 91058 Erlangen, Germany. and Forschungszentrum Jülich, "Helmholtz-Institute Erlangen-Nürnberg for Renewable Energies" (IEK 11), Egerlandstr. 3, 91058 Erlangen, Germany.

Supported liquid phase catalysis has great potential to unify the advantages from both homogeneous and heterogeneous catalysis. Recently, we reported supported catalytically active liquid metal solutions (SCALMS) as a new class of liquid phase catalysts. SCALMS enable high temperature application due to the high thermal stability of liquid metals when compared to supported molten salts or ionic liquids. The highly dynamic liquid metal/gas interface of SCALMS allows for catalysis over single atoms of an active metal atom within a matrix of liquid gallium. In the present study, kinetic data is acquired along the catalyst bed in a compact profile reactor during propane dehydrogenation (PDH) over gallium-platinum SCALMS. The reactor design allows for the analysis of the temperature and gas phase composition along the catalyst bed with a high spatial resolution using a sampling capillary inside the reactor. The concentration profiles suggest enhanced deactivation of the catalyst at the end of the bed with a deactivation front moving from the end to the beginning of the catalyst bed over time on stream. Only minor amounts of side products, formed via cracking of propane, were identified, supporting previously reported high selectivity of SCALMS during alkane dehydrogenation. The acquired data is supported by in situ high-resolution thermogravimetry coupled with mass spectrometry to monitor the activity and coking behaviour of SCALMS during PDH. The results strongly suggest an enhanced formation of coke over Al2O3-supported SCALMS when compared to using SiO2 as the support material.
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http://dx.doi.org/10.1039/d0fd00010hDOI Listing
March 2021

Highly Effective Propane Dehydrogenation Using Ga-Rh Supported Catalytically Active Liquid Metal Solutions.

ACS Catal 2019 Oct 6;9(10):9499-9507. Epub 2019 Sep 6.

Lehrstuhl für Chemische Reaktionstechnik (CRT), Lehrstuhl für Theoretische Chemie, Lehrstuhl für Physikalische Chemie II, and Lehrstuhl für Katalytische Grenzflächenforschung, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Egerlandstr. 3, 91058 Erlangen, Germany.

Our contribution demonstrates that rhodium, an element that has barely been reported as an active metal for selective dehydrogenation of alkanes becomes a very active, selective, and robust dehydrogenation catalyst when exposed to propane in the form of single atoms at the interface of a solid-supported, highly dynamic liquid Ga-Rh mixture. We demonstrate that the transition to a fully liquid supported alloy droplet at Ga/Rh ratios above 80, results in a drastic increase in catalyst activity with high propylene selectivity. The combining results from catalytic studies, X-ray photoelectron spectroscopy, IR-spectroscopy under reaction conditions, microscopy, and density-functional theory calculations, we obtained a comprehensive microscopy picture of the working principle of the Ga-Rh supported catalytically active liquid metal solution.
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http://dx.doi.org/10.1021/acscatal.9b02459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7088128PMC
October 2019

Coke Formation during Propane Dehydrogenation over Ga-Rh Supported Catalytically Active Liquid Metal Solutions.

ChemCatChem 2020 Feb 7;12(4):1085-1094. Epub 2020 Jan 7.

Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Lehrstuhl für Chemische Reaktionstechnik (CRT) Egerlandstr. 3 91058 Erlangen Germany.

Supported Catalytically Active Liquid Metal Solutions (SCALMS) were recently described as a new class of heterogeneous catalysts, where the catalytic transformation takes place at the highly dynamic interface of a liquid alloy. Their application in alkane dehydrogenation has been claimed to be superior to classical heterogeneous catalysts, because the single atom nature of Rh dissolved in liquid Ga hinders the formation of significant amounts of coke, e. g. by oligomerisation of carbon fragments and excessive dehydrogenation. In the present study, we investigate the coking behaviour of Ga-Rh SCALMS during dehydrogenation of propane in detail by means of high-resolution thermogravimetry. We report that the application of Ga-Rh SCALMS indeed limits the formation of coke when compared to the Ga-free Rh catalyst, in particular when relating coke formation to the catalytic performance. Furthermore, the formed coke has been shown to be highly reactive during temperature programmed oxidation in 21 % O/He with onset temperatures of approx. 150 °C enabling a regeneration of the Ga-Rh SCALMS system under mild conditions. The activation energy of the oxidation lies in the lower range of values reported for spent cracking catalysts. Monitoring the formation of coke and performance of SCALMS via thermogravimetry coupled with mass spectrometry revealed the continuous formation of coke, which becomes the only process affecting the net weight change after a certain time on stream.
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http://dx.doi.org/10.1002/cctc.201901922DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7074060PMC
February 2020

Mechanism of the Water-Gas Shift Reaction Catalyzed by Efficient Ruthenium-Based Catalysts: A Computational and Experimental Study.

Angew Chem Int Ed Engl 2019 Jan 12;58(3):741-745. Epub 2018 Dec 12.

Group of Computational Life Sciences, Department of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia.

Supported ionic liquid phase (SILP) catalysis enables a highly efficient, Ru-based, homogeneously catalyzed water-gas shift reaction (WGSR) between 100 °C and 150 °C. The active Ru-complexes have been found to exist in imidazolium chloride melts under operating conditions in a dynamic equilibrium, which is dominated by the [Ru(CO) Cl ] complex. Herein we present state-of-the-art theoretical calculations to elucidate the reaction mechanism in more detail. We show that the mechanism includes the intermediate formation and degradation of hydrogen chloride, which effectively reduces the high barrier for the formation of the requisite dihydrogen complex. The hypothesis that the rate-limiting step involves water is supported by using D O in continuous catalytic WGSR experiments. The resulting mechanism constitutes a highly competitive alternative to earlier reported generic routes involving nucleophilic addition of hydroxide in the gas phase and in solution.
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http://dx.doi.org/10.1002/anie.201811627DOI Listing
January 2019

Ionic-Liquid-Infused Nanostructures as Repellent Surfaces.

Langmuir 2018 06 2;34(23):6894-6902. Epub 2018 Feb 2.

Institute of Particle Technology , Friedrich-Alexander University Erlangen-Nürnberg , Cauerstrasse 4 , 91058 Erlangen , Germany.

In order to prepare lubricant-infused repellent coatings on silica nanostructures using low vapor pressure ionic liquids as lubricants, we study the wetting behavior of a set of imidazolium-based ionic liquids with different alkyl side chains as a function of the applied surface functionalities. We take advantage of the structural color of inverse opals prepared from a colloidal coassembly technique to study the infiltration of ionic liquids into these nanoporous structures. We find that the more hydrophobic ionic liquids with butyl and hexyl side chains can completely infiltrate inverse opals functionalized with mixed self-assembled monolayers composed of imidazole groups and aliphatic hydrocarbon chains, which we introduce via silane chemistry. These molecular species reflect the chemical nature of the ionic liquid, thereby increasing the affinity between the liquid and solid surface. The mixed surface chemistry provides sufficiently small contact angles with the ionic liquid to infiltrate the nanopores while maximizing the contact angle with water. As a result, the mixed monolayers enable the design of a stable ionic liquid/solid interface that is able to repel water as a test liquid. Our results underline the importance of matching chemical affinities to predict and control the wetting behavior in complex, multiphase systems.
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http://dx.doi.org/10.1021/acs.langmuir.7b03993DOI Listing
June 2018

Continuous gas-phase hydroaminomethylation using supported ionic liquid phase catalysts.

Angew Chem Int Ed Engl 2013 Jul 16;52(27):6996-9. Epub 2013 May 16.

Department of Chemical and Bioengineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.

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http://dx.doi.org/10.1002/anie.201301365DOI Listing
July 2013

Rhodium-phosphite SILP catalysis for the highly selective hydroformylation of mixed C4 feedstocks.

Angew Chem Int Ed Engl 2011 May 8;50(19):4492-5. Epub 2011 Apr 8.

Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany.

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http://dx.doi.org/10.1002/anie.201007164DOI Listing
May 2011

Ionic liquids in chemical engineering.

Annu Rev Chem Biomol Eng 2010 ;1:203-30

Lehrstuhl für Chemische Reaktionstechnik, Universität Erlangen-Nürnberg, Erlangen, Germany.

The development of engineering applications with ionic liquids stretches back to the mid-1990s when the first examples of continuous catalytic processes using ionic liquids and the first studies of ionic liquid-based extractions were published. Ever since, the use of ionic liquids has seen tremendous progress in many fields of chemistry and engineering, and the first commercial applications have been reported. The main driver for ionic liquid engineering applications is to make practical use of their unique property profiles, which are the result of a complex interplay of coulombic, hydrogen bonding and van der Waals interactions. Remarkably, many ionic liquid properties can be tuned in a wide range by structural modifications at their cation and anion. This review highlights specific examples of ionic liquid applications in catalysis and in separation technologies. Additionally, the application of ionic liquids as working fluids in process machines is introduced.
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http://dx.doi.org/10.1146/annurev-chembioeng-073009-100915DOI Listing
May 2012

Homogeneous ruthenium-based water-gas shift catalysts via supported ionic liquid phase (SILP) technology at low temperature and ambient pressure.

Phys Chem Chem Phys 2009 Dec 22;11(46):10817-9. Epub 2009 Sep 22.

Lehrstuhl für Chemische Reaktionstechnik, Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 Erlangen, Germany.

Novel ruthenium-based supported ionic liquid phase (SILP) catalysts for the water-gas shift (WGS) reaction are reported which, compared to classical low temperature shift systems, operate at much lower temperatures and even at ambient pressure.
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http://dx.doi.org/10.1039/b912688kDOI Listing
December 2009

Ionic liquids in refinery desulfurization: comparison between biphasic and supported ionic liquid phase suspension processes.

ChemSusChem 2009 ;2(10):969-77

Universität Erlangen-Nürnberg, Lehrstuhl für Chemische Reaktionstechnik, Egerlandstr. 3, 91058 Erlangen, Germany.

The desulfurization of fuel compounds in the presence of ionic liquids is reported. For this purpose, the desulfurization efficiency of a variety of imidazolium phosphate ionic liquids has been tested. Dibenzothiophene/dodecane and butylmercaptan/decane mixtures were used as model systems. Single-stage extractions reduced the sulfur content from 500 ppm to 200 ppm. In multistage extractions the sulfur content could be lowered to less than 10 ppm within seven stages. Regeneration of the ionic liquid was achieved by distillation or re-extraction procedures. Supported ionic liquid phase (SILP) materials, obtained by dispersing the ionic liquid as a thin film on highly porous silica, exhibited a significantly higher extraction performance owing to their larger surface areas, reducing the sulfur content to less than 100 ppm in one stage. Multistage extraction with these SILP materials reduced the sulfur level to 50 ppm in the second stage. The SILP technology offers very efficient utilization of ionic liquids and circumvents mass transport limitations because of the small film thickness and large surface area, and allows application of the simple packed-bed column extraction technique.
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http://dx.doi.org/10.1002/cssc.200900142DOI Listing
February 2010

Hydroformylation in room temperature ionic liquids (RTILs): catalyst and process developments.

Chem Rev 2008 Apr 21;108(4):1474-97. Epub 2008 Mar 21.

Lehrstuhl für Chemische Reaktionstechnik, Universität Erlangen-Nürnberg, Egerlandstrasse 3, D-91058 Erlangen, Germany.

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http://dx.doi.org/10.1021/cr078374zDOI Listing
April 2008

Very stable and highly regioselective supported ionic-liquid-phase (SILP) catalysis: continuous-flow fixed-bed hydroformylation of propene.

Angew Chem Int Ed Engl 2005 Jan;44(5):815-9

Department of Chemistry and Interdisciplinary Research Center for Catalysis, Technical University of Denmark, Building 207, 2800 Kgs. Lyngby, Denmark.

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http://dx.doi.org/10.1002/anie.200461534DOI Listing
January 2005

Synthesis, crystal structure and hydroformylation activity of triphenylphosphite modified cobalt catalysts.

Dalton Trans 2004 Jun 10(11):1679-86. Epub 2004 May 10.

Department of Chemistry and Biochemistry, Rand Afrikaans University, P.O. Box 524, Auckland Park, South Africa 2006.

The dinuclear complex [Co(2)(CO)(6)[P(OPh)3]2] (2) has been synthesised and was fully characterised. The solid state structure revealed a trans diaxial geometry, no bridging carbonyls, and Co-Co and Co-P bond lengths of 2.6722(4) and 2.1224(4) Angstrom, respectively. Catalysed hydroformylation of 1-pentene with 2 was attempted at temperatures in the range 120 to 210 degrees C and pressures between 34 and 80 bar. High pressure spectroscopy (HP-IR and HP-NMR) was used to detect hydride intermediates. High pressure infrared (HP-IR) studies revealed the formation of [HCo(CO)(3)P(OPh)3] (4) at ca. 110 degrees C, but at higher temperatures absorption bands corresponding to [HCo(CO)(4)]() were observed. The hydride intermediate 4 has also been synthesised and characterised. Upon increased ligand concentration, HP-IR studies showed the formation of new carbonyl absorption bands due to a higher substituted cobalt carbonyl complex-[HCo(CO)(2)[P(OPh)3]2] (5), which is believed to be catalytically less active. Complex 5 has been synthesised independently and was fully characterised. A low temperature crystal structural study of 5 revealed a trigonal bipyramidal structure with a trans H-Co-CO arrangement and two equatorial phosphite ligands, the Co-P bond lengths being 2.1093(8) and 2.1076(8)[Angstrom], respectively.
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http://dx.doi.org/10.1039/b403033hDOI Listing
June 2004