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Ridder H, Sinn C, Pesch GR, Dreher W, Thöming J. Longitudinal Relaxation ( T 1) of Methane/Hydrogen Mixtures for Operando Characterization of Gas-Phase Reactions. ACS Meas Sci Au 2022; 2:449-456. [PMID: 36785657 PMCID: PMC9885991 DOI: 10.1021/acsmeasuresciau.2c00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/11/2022] [Accepted: 07/11/2022] [Indexed: 06/18/2023]
Abstract
Catalytic hydrogenation reactions are important in a modern hydrogen-based society. To optimize these gas-phase reactions, a deep understanding of heat, mass, and momentum transfer inside chemical reactors is required. Nuclear magnetic resonance (NMR) measurements can be used to obtain spatially resolved values of temperature, gas composition, and velocity in the usually opaque catalytic macrostructures. For this, the desired values are calculated from measured NMR parameters like signal amplitude, T 1, or T 2. However, information on how to calculate target values from these NMR parameters in gases is scarce, especially for mixtures of gases. To enable detailed NMR studies of hydrogenation reactions, we investigated the T 1 relaxation of methane and hydrogen, which are two gases commonly present in hydrogenation reactions. To achieve industrially relevant conditions, the temperatures are varied from 290 to 600 K and the pressure from 1 bara to 5 bara, using different mixtures of methane and hydrogen. The results show that hydrogen, which is usually considered to be nondetectable in standard MRI sequences, can be measured at high concentrations, starting at a pressure of 3 bara even at temperatures above 400 K. In the investigated parameter range, the absolute T 1 values of hydrogen show only small dependence on temperature, pressure, and composition, while T 1 of methane is highly dependent on all three parameters. At a pressure of 5 bara, the measured values of T 1 for methane agree very well with theoretical predictions, so that they can also be used for temperature calculations. Further, it can be shown that the same measurement technique can be used to accurately calculate gas ratios inside each voxel. In conclusion, this study covers important aspects of spatially resolved operando NMR measurements of gas-phase properties during hydrogenation reactions at industrially relevant conditions to help improve chemical processes in the gas phase.
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Affiliation(s)
- Harm Ridder
- Chemical
Process Engineering (CVT), Faculty of Production Engineering, University of Bremen, Leobener Str. 6, 28359 Bremen, Germany
- Center
for Environmental Research and Sustainable Technology (UFT), Post box 330 440, 28334 Bremen, Germany
| | - Christoph Sinn
- Chemical
Process Engineering (CVT), Faculty of Production Engineering, University of Bremen, Leobener Str. 6, 28359 Bremen, Germany
- Center
for Environmental Research and Sustainable Technology (UFT), Post box 330 440, 28334 Bremen, Germany
| | - Georg R. Pesch
- Chemical
Process Engineering (CVT), Faculty of Production Engineering, University of Bremen, Leobener Str. 6, 28359 Bremen, Germany
- Center
for Environmental Research and Sustainable Technology (UFT), Post box 330 440, 28334 Bremen, Germany
- MAPEX
Center for Materials and Processes, University
of Bremen, Post box 330 440, 28334 Bremen, Germany
| | - Wolfgang Dreher
- in
vivo MR group, Faculty of Chemistry, University
of Bremen, Leobener Str.
NW2, 28359 Bremen, Germany
| | - Jorg Thöming
- Chemical
Process Engineering (CVT), Faculty of Production Engineering, University of Bremen, Leobener Str. 6, 28359 Bremen, Germany
- Center
for Environmental Research and Sustainable Technology (UFT), Post box 330 440, 28334 Bremen, Germany
- MAPEX
Center for Materials and Processes, University
of Bremen, Post box 330 440, 28334 Bremen, Germany
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Ridder H, Sinn C, Pesch GR, Ilsemann J, Dreher W, Thöming J. A large fixed bed reactor for MRI operando experiments at elevated temperature and pressure. Rev Sci Instrum 2021; 92:043711. [PMID: 34243384 DOI: 10.1063/5.0044795] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 04/04/2021] [Indexed: 06/13/2023]
Abstract
Recently, in situ studies using nuclear magnetic resonance (NMR) have shown the possibility to monitor local transport phenomena of gas-phase reactions inside opaque structures. Their application to heterogeneously catalyzed reactions remains challenging due to inherent temperature and pressure constraints. In this work, an NMR-compatible reactor was designed, manufactured, and tested, which can endure high temperatures and increased pressure. In temperature and pressure tests, the reactor withstood pressures up to 28 bars at room temperature and temperatures over 400 °C and exhibited only little magnetic shielding. Its applicability was demonstrated by performing the CO2 methanation reaction, which was measured operando for the first time by using a 3D magnetic resonance spectroscopic imaging sequence. The reactor design is described in detail, allowing its easy adaptation for different chemical reactions and other NMR measurements under challenging conditions.
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Affiliation(s)
- Harm Ridder
- Chemical Process Engineering (CVT), Faculty of Production Engineering (FB 4), University of Bremen, Leobener Straße 6, 28359 Bremen, Germany
| | - Christoph Sinn
- Chemical Process Engineering (CVT), Faculty of Production Engineering (FB 4), University of Bremen, Leobener Straße 6, 28359 Bremen, Germany
| | - Georg R Pesch
- Chemical Process Engineering (CVT), Faculty of Production Engineering (FB 4), University of Bremen, Leobener Straße 6, 28359 Bremen, Germany
| | - Jan Ilsemann
- Faculty of Chemistry (FB 2), Institute of Applied Physical and Chemistry (IAPC), University of Bremen, Leobener Straße 6, 28359 Bremen, Germany
| | - Wolfgang Dreher
- In vivo MR Group, Faculty of Chemistry (FB 2), University of Bremen, Leobener Straße NW2, 28359 Bremen, Germany
| | - Jorg Thöming
- Chemical Process Engineering (CVT), Faculty of Production Engineering (FB 4), University of Bremen, Leobener Straße 6, 28359 Bremen, Germany
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Sinn C, Wentrup J, Pesch GR, Thöming J. Heat Transport in Open-Cell Foams: CFD Analysis of Artificial Heat Sources vs Fully Resolved Exothermal Reactions. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.0c05982] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christoph Sinn
- Chemical Process Engineering, University of Bremen, Leobener Strasse 6, 28359 Bremen, Germany
| | - Jonas Wentrup
- Chemical Process Engineering, University of Bremen, Leobener Strasse 6, 28359 Bremen, Germany
| | - Georg R. Pesch
- Chemical Process Engineering, University of Bremen, Leobener Strasse 6, 28359 Bremen, Germany
- MAPEX Center for Materials and Processes, University of Bremen, Postbox 330
440, 28334 Bremen, Germany
| | - Jorg Thöming
- Chemical Process Engineering, University of Bremen, Leobener Strasse 6, 28359 Bremen, Germany
- MAPEX Center for Materials and Processes, University of Bremen, Postbox 330
440, 28334 Bremen, Germany
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Sinn C, Wentrup J, Pesch GR, Thöming J, Kiewidt L. Structure-heat transport analysis of periodic open-cell foams to be used as catalyst carriers. Chem Eng Res Des 2021. [DOI: 10.1016/j.cherd.2020.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Sinn C, Woermann D. Static light scattering experiments with aqueous solutions of the nonionic tenside C12E5with critical and non-critical composition. ACTA ACUST UNITED AC 2014. [DOI: 10.1002/bbpc.19920960711] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Heymann A, Sinn C, Palberg T. Particle characterization using multiple scattering decorrelation methods: hard-sphere model system. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 2000; 62:813-820. [PMID: 11088538 DOI: 10.1103/physreve.62.813] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/1999] [Indexed: 05/23/2023]
Abstract
Applying static light scattering experiments, we characterize colloidal particles that are used as model hard-sphere systems in experiments investigating their crystallization kinetics. The particles comprise of a compact core of poly(methyl methacrylate) and short polymer hairs grafted onto the surface. We use a contrast variation procedure to determine the refractive index variation within the particles and observe that one component of the binary mixture used as a solvent penetrates the particles and masks completely the small polymer hairs. Making use of the determined refractive index variation, we obtain the average particle radius and its polydispersity from measurements of the particle form factor close to its minimae. The scattered intensity has been corrected carefully for multiple scattering contributions applying dynamic light scattering measurements with multiple scattering decorrelation. We obtain a mean particle radius of &Rmacr;=435+/-4 nm and a polydispersity of sigma=2.5%, a resolution that has not been achieved with light scattering experiments before.
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Affiliation(s)
- A Heymann
- Institut fur Physik der Johannes-Gutenberg-Universitat, Mainz, Germany
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Overbeck E, Sinn C, Watzlawek M. Enhanced structural correlations accelerate diffusion in charge-stabilized colloidal suspensions. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics 1999; 60:1936-9. [PMID: 11969984 DOI: 10.1103/physreve.60.1936] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/1998] [Revised: 03/30/1999] [Indexed: 04/18/2023]
Abstract
Theoretical calculations for colloidal charge-stabilized suspensions and hard-sphere suspensions show that hydrodynamic interactions yield a qualitatively different particle concentration dependence of the short-time self-diffusion coefficient. The effect, however, is numerically small and hardly accessible by conventional light-scattering experiments. By applying multiple-scattering decorrelation equipment and a careful data analysis we show that the theoretical prediction for charged particles is in agreement with our experimental results from aqueous polystyrene latex suspensions.
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Affiliation(s)
- E Overbeck
- Institut für Physik der Johannes-Gutenberg-Universität, 55099 Mainz, Germany
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Heymann A, Stipp A, Sinn C, Palberg T. Observation of Oriented Close-Packed Lattice Planes in Polycrystalline Hard-Sphere Solids. J Colloid Interface Sci 1998; 207:119-127. [PMID: 9778398 DOI: 10.1006/jcis.1998.5761] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report time-resolved Bragg scattering experiments on solidifying colloidal suspensions of hard spheres. The polar angle-averaged, integrated intensity of the (111) and (311) reflections show a transient, two-step behavior below melting, which depends in a complex way on the volume fraction and is not present for (200) or (220). Detailed analysis of the full two-dimensional scattering pattern reveals intensity maxima of sixfold symmetry close to the position of the (111) and (311) Debye-Scherrer rings. These can be explained assuming oriented crystals with close-packed planes parallel to the container walls. We show that the observed temporal behavior is due to competing homogeneous and heterogeneous nucleation and growth scenarios. Copyright 1998 Academic Press.
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Affiliation(s)
- A Heymann
- Institut für Physik der, Johannes-Gutenberg-Universität, Staudingerweg 7, Mainz, 55099, Germany
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Eichhorn K, Sinn C, Dettenmaier M. Effect of uniaxial deformation on the optical scattering losses of a semicrystalline fluorocopolymer. Appl Opt 1997; 36:4259-4264. [PMID: 18253453 DOI: 10.1364/ao.36.004259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Both small- and wide-angle light scattering as well as transmission measurements have been used to investigate the optical scattering losses of a vinylidene difluoride-tetrafluoroethylene-hexafluoropropylene copolymer crystallized from the melt. The main origin of the scattering loss is the wide-angle light scattering from the spherulitic superstructure. Uniaxial deformation transforms this structure into a fiber morphology. The attenuation of fibers has been measured for light propagating both parallel and perpendicular to the orientation axis. For both directions, the attenuation decreases with increasing draw ratio. Annealing of the fibers while keeping their ends fixed is an effective method to reduce the attenuation further, to a low value as close to that of the melt.
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Freimuth H, Sinn C, Dettenamaier M. Structure and deformation behaviour of a vinylidene fluoride—tetrafluoroethylene— hexafluoropropylene terpolymer. POLYMER 1996. [DOI: 10.1016/0032-3861(96)87261-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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