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Seidl V, Romero AH, Heinemann FW, Scheurer A, Vogel CS, Unruh T, Wasserscheid P, Meyer K. A New Class of Task‐Specific Imidazolium Salts and Ionic Liquids and Their Corresponding Transition‐Metal Complexes for Immobilization on Electrochemically Active Surfaces. Chemistry 2022; 28:e202200100. [PMID: 35172023 PMCID: PMC9315159 DOI: 10.1002/chem.202200100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Indexed: 11/12/2022]
Abstract
Adding to the versatile class of ionic liquids, we report the detailed structure and property analysis of a new class of asymmetrically substituted imidazolium salts, offering interesting thermal characteristics, such as liquid crystalline behavior, polymorphism or glass transitions. A scalable general synthetic procedure for N‐polyaryl‐N’‐alkyl‐functionalized imidazolium salts with para‐substituted linker (L) moieties at the aryl chain, namely [LPhmImHR]+ (L=Br, CN, SMe, CO2Et, OH; m=2, 3; R=C12, PEGn; n=2, 3, 4), was developed. These imidazolium salts were studied by single‐crystal X‐ray diffraction (SC‐XRD), NMR spectroscopy and thermochemical methods (DSC, TGA). Furthermore, these imidazolium salts were used as N‐heterocyclic carbene (NHC) ligand precursors for mononuclear, first‐row transition metal complexes (MnII, FeII, CoII, NiII, ZnII, CuI, AgI, AuI) and for the dinuclear Ti‐supported Fe‐NHC complex [(OPy)2Ti(OPh2ImC12)2(FeI2)] (OPy=pyridin‐2‐ylmethanolate). The complexes were studied concerning their structural and magnetic behavior via multi‐nuclear NMR spectroscopy, SC‐XRD analyses, variable temperature and field‐dependent (VT‐VF) SQUID magnetization methods, X‐band EPR spectroscopy and, where appropriate, zero‐field 57Fe Mössbauer spectroscopy.
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Seidl V, Romero AH, Heinemann FW, Scheurer A, Vogel CS, Unruh T, Wasserscheid P, Meyer K. Cover Feature: A New Class of Task‐Specific Imidazolium Salts and Ionic Liquids and Their Corresponding Transition‐Metal Complexes for Immobilization on Electrochemically Active Surfaces (Chem. Eur. J. 20/2022). Chemistry 2022. [DOI: 10.1002/chem.202200812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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28
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Søgaard A, de Oliveira AL, Taccardi N, Haumann M, Wasserscheid P. Ga-Ni supported catalytically active liquid metal solutions (SCALMS) for selective ethylene oligomerization. Catal Sci Technol 2021; 11:7535-7539. [PMID: 34912539 PMCID: PMC8630613 DOI: 10.1039/d1cy01146d] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/10/2021] [Indexed: 11/21/2022]
Abstract
Non-precious metal supported catalytically active liquid metal solutions exhibit attractive performance in ethylene oligomerization. It is found for the Ga-Ni system on silica that the performance depends strongly on the applied Ga/Ni ratio. Ga-rich systems forming liquid alloys exhibit a far higher Ni-based catalytic activity than solid intermetallic compounds or Ni nanoparticles.
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Raman N, Wolf M, Heller M, Heene-Würl N, Taccardi N, Haumann M, Felfer P, Wasserscheid P. GaPt Supported Catalytically Active Liquid Metal Solution Catalysis for Propane Dehydrogenation-Support Influence and Coking Studies. ACS Catal 2021; 11:13423-13433. [PMID: 34777909 PMCID: PMC8576810 DOI: 10.1021/acscatal.1c01924] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Indexed: 01/10/2023]
Abstract
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Supported catalytically
active liquid metal solutions (SCALMS)
of Pt in Ga (2 at.-% Pt) were studied in the temperature range of
500 to 600 °C for propane dehydrogenation. A facile synthesis
procedure using ultrasonication was implemented and compared to a
previously reported organo-chemical route for gallium deposition.
The procedure was applied to synthesize GaPt-SCALMS catalyst on silica
(SiO2), alumina (Al2O3), and silicon
carbide (SiC) to investigate the effect of the support material on
the catalytic performance. The SiC-based SCALMS catalyst showed the
highest activity, while SiO2-based SCALMS showed the highest
stability and lowest cracking tendency at higher temperatures. The
selectivity toward propene for the SiO2-based catalyst
remained above 93% at 600 °C. The catalysts were analyzed for
coke content after use by temperature-programmed oxidation (TPO) and
Raman spectroscopy. While the SiC- and SiO2-supported SCALMS
systems showed hardly any coke formation, the Al2O3-supported systems suffered from pronounced coking. SEM-EDX
analyses of the catalysts before and after reaction indicated that
no perceivable morphological changes occur during reaction. The SCALMS
catalysts under investigation are compared with supported Pt and supported
GaPt solid-phase catalyst, and possible deactivation pathways are
discussed.
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Hohner C, Fromm L, Schuschke C, Taccardi N, Xu T, Wasserscheid P, Görling A, Libuda J. Adsorption Motifs and Molecular Orientation at the Ionic Liquid/Noble Metal Interface: [C 2C 1Im][NTf 2] on Pt(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:12596-12607. [PMID: 34661413 DOI: 10.1021/acs.langmuir.1c01900] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In solid catalysts with ionic liquid layers (SCILLs), ionic liquid (IL) thin films are used to modify the activity and selectivity of catalytic materials. In this work, we investigated the adsorption behavior of the IL 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide [C2C1Im][NTf2] on Pt(111) by combining experimental and theoretical studies. Under ultrahigh vacuum (UHV) conditions, the IL was deposited onto a Pt(111) single crystal surface by physical vapor deposition (PVD) at different surface temperatures (200, 300, and 400 K). The adsorption process was monitored by in situ infrared reflection absorption spectroscopy (IRAS). Complementary to the IRAS studies, we performed density functional theory (DFT) calculations and analyzed the adsorption motifs and orientation of the IL ions. In total, we calculated four different systems: (a) [C2C1Im]+ and [NTf2]- ions in the gas phase; [NTf2]- anions in (b) small (4 × 4) and (c) large (6 × 6) Pt(111) supercells; and (d) a complete ion pair of [C2C1Im][NTf2] in a (6 × 6) Pt(111) supercell. Based on DFT, we simulated IR spectra and compared them to the experimental data. Our results suggest that the binding motif and orientation of the IL is strongly dependent on the actual IL coverage. In the monolayer (ML), [NTf2]- interacts strongly with the metal surface and adopts a specific orientation in which it interacts with the Pt surface via the SO2 groups. Also the [C2C1Im]+ cations adopt a preferential orientation up to coverages of 1 ML. Upon transition to the multilayer region, the specific orientation of the ions is gradually lost.
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31
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Eschenbacher R, Schuschke C, Bühlmeyer H, Taccardi N, Wasserscheid P, Bauer T, Xu T, Libuda J. Interaction between Ionic Liquids and a Pt(111) Surface Probed by Coadsorbed CO as a Test Molecule. J Phys Chem Lett 2021; 12:10079-10085. [PMID: 34624196 DOI: 10.1021/acs.jpclett.1c02983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We used temperature-programmed infrared reflection absorption spectroscopy (TP-IRAS) to study the desorption behavior of CO on Pt(111) coadsorbed with four kinds of ionic liquids (ILs), namely 1-butyl-1-methyl-pyrrolidinium-bis(trifluoromethylsulfonyl)imide ([C4C1Pyr][NTf2]), 1-ethyl-3-methyl-imidazolium-bis(trifluoromethylsulfonyl)imide ([C2C1Im][NTf2]), 1-butyl-1-methyl-pyrrolidinium-trifluoro-methanesulfonate ([C4C1Pyr][OTf]), and 1-butyl-1-methyl-pyrrolidinium-hexafluorophosphate ([C4C1Pyr][PF6]). We found that CO desorbs earlier from a Pt(111) surface with coadsorbed ILs than without. In addition, the CO desorption temperature varies between different types of coadsorbed ILs, which follows the order: [C4C1Pyr][PF6] (365 K) > [C4C1Pyr][NTf2] (362 K) > [C2C1Im][NTf2] (352 K) > [C4C1Pyr][OTf] (348 K). We ascribe the difference in CO desorption temperature to the different interaction strength between ILs and the Pt(111) surface. A stronger IL-Pt(111) interaction leads to a lower CO desorption temperature. We suggest that TP-IRAS experiments of CO coadsorbed with ILs can be a useful method to aid the characterization of the interaction strength between ILs and metal surfaces such as Pt(111).
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32
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Schuster R, Wähler T, Kettner M, Agel F, Bauer T, Wasserscheid P, Libuda J. Model Studies on the Ozone-Mediated Synthesis of Cobalt Oxide Nanoparticles from Dicobalt Octacarbonyl in Ionic Liquids. ChemistryOpen 2021; 10:141-152. [PMID: 33565717 PMCID: PMC7874506 DOI: 10.1002/open.202000187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Low-temperature synthesis in ionic liquids (ILs) offers an efficient route for the preparation of metal oxide nanomaterials with tailor-made properties in a water-free environment. In this work, we investigated the role of 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [C4 C1 Pyr][NTf2 ] in the synthesis of cobalt oxide nanoparticles from the molecular precursor Co2 (CO)8 with ozone. We performed a model study in ultra-clean, ultrahigh vacuum (UHV) conditions by infrared reflection absorption spectroscopy (IRAS) using Au(111) as a substrate. Exposure of the pure precursor to ozone at low temperatures results in the oxidation of the first layers, leading to the formation of a disordered Cox Oy passivation layer. Similar protection to ozone is also achieved by deposition of an IL layer onto a precursor film prior to ozone exposure. With increasing temperature, the IL gets permeable for ozone and a cobalt oxide film forms at the IL/precursor interface. We show that the interaction with the IL mediates the oxidation and leads to a more densely packed Cox Oy film compared to a direct oxidation of the precursor.
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33
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Moioli E, Schmid L, Wasserscheid P, Freund H. Kinetic modelling of reactions for the synthesis of 2-methyl-5-ethyl pyridine. REACT CHEM ENG 2021. [DOI: 10.1039/d1re00085c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The kinetics of the reactions for the synthesis of 2-methyl-5-ethyl pyridine (MEP) were investigated systematically by means of operando Raman spectroscopy.
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34
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Wolf M, Raman N, Taccardi N, Horn R, Haumann M, Wasserscheid P. Capturing spatially resolved kinetic data and coking of Ga–Pt supported catalytically active liquid metal solutions during propane dehydrogenation in situ. Faraday Discuss 2021; 229:359-377. [DOI: 10.1039/d0fd00010h] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Spatially resolved kinetic data of gallium–platinum SCALMS was captured while elucidating the effect of carrier material on coke formation.
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35
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Kosider A, Blaumeiser D, Schötz S, Preuster P, Bösmann A, Wasserscheid P, Libuda J, Bauer T. Enhancing the feasibility of Pd/C-catalyzed formic acid decomposition for hydrogen generation – catalyst pretreatment, deactivation, and regeneration. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00300c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Formic acid decomposition (FAD) generates H2 at low temperatures. CO poisoning inhibits FAD but is lifted under oxidative treatment.
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36
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Zaitsau DH, Gantman M, Schulz P, Wasserscheid P, Verevkin SP. Volatility of molten salts [Ph
4
P][NTf
2
] and Cs[NTf
2
]. Chemistry 2020. [PMCID: PMC7874263 DOI: 10.1002/open.202000260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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37
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Konnova ME, Li S, Bösmann A, Müller K, Wasserscheid P, Andreeva IV, Turovtzev VV, Zaitsau DH, Pimerzin AA, Verevkin SP. Thermochemical Properties and Dehydrogenation Thermodynamics of Indole Derivates. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c04069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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38
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Schuehle P, Schmitt M, Schill L, Riisager A, Wasserscheid P, Albert J. The influence of gas impurities on the performance of In
2
O
3
/ZrO
2
catalysts for CO
2
hydrogenation to methanol. CHEM-ING-TECH 2020. [DOI: 10.1002/cite.202055090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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39
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Sebastian O, Nair S, Taccardi N, Wolf M, Søgaard A, Haumann M, Wasserscheid P. Stable and Selective Dehydrogenation of Methylcyclohexane using Supported Catalytically Active Liquid Metal Solutions – Ga
52
Pt/SiO
2
SCALMS. ChemCatChem 2020. [DOI: 10.1002/cctc.202000671] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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40
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Claußnitzer J, Bertleff B, Korth W, Albert J, Wasserscheid P, Jess A. Kinetics of Triphase Extractive Oxidative Desulfurization of Benzothiophene with Molecular Oxygen Catalyzed by HPA‐5. Chem Eng Technol 2020. [DOI: 10.1002/ceat.201900448] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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41
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Wolf M, Raman N, Taccardi N, Haumann M, Wasserscheid P. Coke Formation during Propane Dehydrogenation over Ga-Rh Supported Catalytically Active Liquid Metal Solutions. ChemCatChem 2020; 12:1085-1094. [PMID: 32194874 PMCID: PMC7074060 DOI: 10.1002/cctc.201901922] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/23/2019] [Indexed: 11/06/2022]
Abstract
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 % O2/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 in situ 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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42
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Schühle P, Schmidt M, Schill L, Riisager A, Wasserscheid P, Albert J. Influence of gas impurities on the hydrogenation of CO 2 to methanol using indium-based catalysts. Catal Sci Technol 2020. [DOI: 10.1039/d0cy00946f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, the performance of an In2O3/ZrO2 catalyst for hydrogenation of CO2 to methanol is reported in the presence of typical impurities of industrial CO2 feed gas streams.
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43
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Blaumeiser D, Stepić R, Wolf P, Wick CR, Haumann M, Wasserscheid P, Smith DM, Smith AS, Bauer T, Libuda J. Cu carbonyls enhance the performance of Ru-based SILP water–gas shift catalysts: a combined in situ DRIFTS and DFT study. Catal Sci Technol 2020. [DOI: 10.1039/c9cy01852b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In situ DRIFT spectroscopy and DFT identify Cu carbonyl shuttles that enhance the performance of Ru-based SILP water–gas shift catalysts.
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44
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Heßelmann C, Wolf T, Galgon F, Körner C, Albert J, Wasserscheid P. Additively manufactured RANEY®-type copper catalyst for methanol synthesis. Catal Sci Technol 2020. [DOI: 10.1039/c9cy01657k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe a novel approach to prepare cellular methanol synthesis catalysts by combining additive manufacturing (AM) of a Cu–Al alloy followed by selective leaching of Al with aqueous NaOH solutions.
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45
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Bachmann P, Steinhauer J, Späth F, Düll F, Bauer U, Eschenbacher R, Hemauer F, Scheuermeyer M, Bösmann A, Büttner M, Neiß C, Görling A, Wasserscheid P, Steinrück HP, Papp C. Dehydrogenation of the liquid organic hydrogen carrier system 2-methylindole/2-methylindoline/2-methyloctahydroindole on Pt(111). J Chem Phys 2019; 151:144711. [DOI: 10.1063/1.5112835] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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46
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Raman N, Maisel S, Grabau M, Taccardi N, Debuschewitz J, Wolf M, Wittkämper H, Bauer T, Wu M, Haumann M, Papp C, Görling A, Spiecker E, Libuda J, Steinrück HP, Wasserscheid P. Highly Effective Propane Dehydrogenation Using Ga-Rh Supported Catalytically Active Liquid Metal Solutions. ACS Catal 2019; 9:9499-9507. [PMID: 32219008 PMCID: PMC7088128 DOI: 10.1021/acscatal.9b02459] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/26/2019] [Indexed: 11/28/2022]
Abstract
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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47
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Sintra TE, Gantman MG, Ventura SP, Coutinho JA, Wasserscheid P, Schulz PS. Synthesis and characterization of chiral ionic liquids based on quinine, l-proline and l-valine for enantiomeric recognition. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.03.084] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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48
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Bauer T, Maisel S, Blaumeiser D, Vecchietti J, Taccardi N, Wasserscheid P, Bonivardi A, Görling A, Libuda J. Operando DRIFTS and DFT Study of Propane Dehydrogenation over Solid- and Liquid-Supported Ga x Pt y Catalysts. ACS Catal 2019; 9:2842-2853. [PMID: 32477699 PMCID: PMC7252903 DOI: 10.1021/acscatal.8b04578] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/05/2019] [Indexed: 11/29/2022]
Abstract
![]()
Supported catalytically
active liquid metal solutions (SCALMS)
represent a class of catalytic materials that have only recently been
developed, but have already proven to be highly active, e.g., for
dehydrogenation reactions. Previous studies attributed the catalytic
activity to isolated noble metal atoms at the surface of a liquid
and inert Ga matrix. In this study, we apply diffuse reflectance infrared
Fourier transform spectroscopy (DRIFTS) with CO as a probe molecule
to Ga/Al2O3, Pt/Al2O3,
and Ga37Pt/Al2O3 catalysts, to investigate
in detail the nature of the active Pt species. Comparison of CO adsorption
on Pt/Al2O3 and Ga37Pt/Al2O3 shows that isolated Pt atoms are, indeed, present at
the surface of the liquid SCALMS. Combining DRIFTS with online gas
chromatography (GC), we investigated the Ga/Al2O3, Pt/Al2O3, and Ga37Pt/Al2O3 systems under operando conditions during propane dehydrogenation
in CO/propane and in Ar/propane. We find that the Pt/Al2O3 sample is rapidly poisoned by CO adsorption and coke,
whereas propane dehydrogenation over Ga37Pt/Al2O3 SCALMS leads to higher conversion with no indication
of poisoning effects. We show under operando conditions that isolated
Pt atoms are present at the surface of SCALMS during the dehydrogenation
reaction. IR spectra and density-functional theory (DFT) suggest that
both the Ga matrix and the presence of coadsorbates alter the electronic
properties of the surface Pt species.
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49
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Søgaard A, Scheuermeyer M, Bösmann A, Wasserscheid P, Riisager A. Homogeneously-catalysed hydrogen release/storage using the 2-methylindole/2-methylindoline LOHC system in molten salt-organic biphasic reaction systems. Chem Commun (Camb) 2019; 55:2046-2049. [PMID: 30687857 DOI: 10.1039/c8cc09883b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ir-Complex catalysed hydrogen release/storage using a 2-methylindole/2-methylindoline Liquid Organic Hydrogen Carrier (LOHC) system is shown to be effective in a temperature range of 120 to 140 °C. In the form of a liquid-liquid biphasic reaction system with molten [PPh4][NTf2] as catalyst immobilisation phase, the applied cationic Ir-complex can be easily separated and recycled enabling a small amount of ionic catalyst solution to store/release a large amount of hydrogen.
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50
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Stepić R, Wick CR, Strobel V, Berger D, Vučemilović-Alagić N, Haumann M, Wasserscheid P, Smith AS, Smith DM. Mechanism of the Water-Gas Shift Reaction Catalyzed by Efficient Ruthenium-Based Catalysts: A Computational and Experimental Study. Angew Chem Int Ed Engl 2019; 58:741-745. [PMID: 30467935 DOI: 10.1002/anie.201811627] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Indexed: 11/07/2022]
Abstract
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)3 Cl3 ]- 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 D2 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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