Thermophysical Studies of Dibenzyltoluene and Its Partially and Fully Hydrogenated Derivatives

Aslam, Rabya; Khan, Muhammad Hashim; Ishaq, Muhammad; Müller, Karsten

doi:10.1021/acs.jced.8b00652

Cited by 41 publications

(21 citation statements)

References 31 publications

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“…Based on the initial composition, the mixture density is determined as a function of the reaction temperature. The density correlations can be taken from [24].…”

Section: Coupling Of Reactor and Membrane Separatormentioning

confidence: 99%

“…Peaks of the fully loaded form (18H-DBT) and the fully unloaded form (0H-DBT) were calibrated with a standard of the pure components and the peaks of the intermediates (6H-DBT, 12H-DBT) were linearly interpolated between 18H-DBT and 0H-DBT, as they are not available in pure form. The interpolation is well justified because the refractive index changes proportionally to the degree of hydrogenation (DoH) [24]. The DoH describes the actual amount of bound hydrogen atoms in relation to the maximum possible quantity of hydrogen atoms that can be bound (see Equation (4)).…”

Section: Analysis Of Product Liquidmentioning

confidence: 99%

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Hydrogen Production from the LOHC Perhydro-Dibenzyl-Toluene and Purification Using a 5 µm PdAg-Membrane in a Coupled Microstructured System

Wunsch¹,

Berg²,

Pfeifer³

2020

Materials

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Hydrogen bound in organic liquid hydrogen carriers (LOHC) such as dibenzyl-toluene enables simple and safe handling as well as long-term storage. This idea is particularly interesting in the context of the energy transition, where hydrogen is considered a key energy carrier. The LOHC technology serves as a storage between volatile energy and locally and timely independent consumption. Depending on the type of application, decisive specifications are placed on the hydrogen purity. In the product gas from dehydrogenation, however, concentrations of 100 to a few 1000 ppm can be found from low boiling substances, which partly originate from the production of the LOHC material, but also from the decomposition and evaporation of the LOHC molecules in the course of the enormous volume expansion due to hydrogen release. For the removal of undesired traces in the LOHC material, a pre-treatment and storage under protective gas is necessary. For purification, the use of Pd-based membranes might be useful, which makes these steps less important or even redundant. Heat supply and phase contacting of the liquid LOHC and catalyst is also crucial for the process. Within the contribution, the first results from a coupled microstructured system—consisting of a radial flow reactor unit and membrane separation unit—are shown. In a first step, the 5 µm thick PdAg-membrane was characterized and a high Sieverts exponent of 0.9 was determined, indicating adsorption/desorption driven permeation. It can be demonstrated that hydrogen is first released with high catalyst-related productivity in the reactor system and afterwards separated and purified. Within the framework of limited analytics, we found that by using a Pd-based membrane, a quality of 5.0 (99.999% purity) or higher can be achieved. Furthermore, it was found that after only 8 hours, the membrane can lose up to 30% of its performance when exposed to the slightly contaminated product gas from the dehydrogenation process. However, the separation efficiency can almost completely be restored by the treatment with pure hydrogen.

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“…Based on the initial composition, the mixture density is determined as a function of the reaction temperature. The density correlations can be taken from [24].…”

Section: Coupling Of Reactor and Membrane Separatormentioning

confidence: 99%

Section: Analysis Of Product Liquidmentioning

confidence: 99%

Hydrogen Production from the LOHC Perhydro-Dibenzyl-Toluene and Purification Using a 5 µm PdAg-Membrane in a Coupled Microstructured System

Wunsch¹,

Berg²,

Pfeifer³

2020

Materials

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“…From eq 3, the refractive index for the H0-DPM was calculated at a wavelength of 514.5 nm, which deviates on average −0.68% from the value reported by Rubio et al 49 within the temperature range studied in the present work. Aslam et al 50 measured the refractive index of H0-DBT and H18-DBT between 293.15 and 343.15 K in steps of 5 K. Except for temperatures from 298.15 to 308.15 K, the data sets are outside the combined uncertainties, which seems to be related to different purities and/or isomeric compositions of the samples used by Aslam et al and in the present study.…”

Section: ■ Results and Discussionmentioning

confidence: 50%

Thermal Conductivity of Hydrocarbon Liquid Organic Hydrogen Carrier Systems: Measurement and Prediction

et al. 2020

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In this study, the thermal conductivity of diphenylmethane, benzyltoluene, and dibenzyltoluene and their fully hydrogenated counterparts relevant in the context of the liquid organic hydrogen carrier (LOHC) technology was investigated. For the determination of the thermal conductivity between 298.15 and 323.15 K at atmospheric pressure with an expanded uncertainty of 5% (k = 2), a steady-state guarded parallel-plate instrument was used. To discuss the thermal conductivity over a broader temperature range, measurements were also performed for the density of the pure LOHCs and binary mixtures of diphenylmethane and dicyclohexylmethane between 293.15 and 363.15 K by vibrating tube densimetry as well as for the thermal diffusivity and the Fick diffusion coefficient of binary mixtures of diphenylmethane or dicyclohexylmethane with dissolved hydrogen between 323 and 573 K and pressures between 2.7 and 6.2 MPa by dynamic light scattering (DLS). In general, the measured thermal conductivities of the compounds under investigation decrease with increasing temperature and molar mass and with the degree of hydrogenation. For mixtures of diphenylmethane and dicyclohexylmethane, the concentration dependency of the thermal conductivity shows a distinct nonideal behavior. Based on the measured thermal conductivities of the present pure substances and reference data from the literature for selected cyclic hydrocarbons, a prediction method for the thermal conductivity of such systems could be developed, which requires the molar mass and density as sole input parameters. This correlation represents the thermal conductivity of the selected dehydrogenated and hydrogenated substances and of the studied binary mixture between 298 K and their normal boiling temperature, typically within 5%. By comparison with the thermal conductivity data for diphenylmethane and dicyclohexylmethane deduced from the measurement results for thermal diffusivity and density and from literature data for the specific heat, it was found that the prediction method also allows for a reliable estimation of the thermal conductivity of LOHCs up to a temperature of 573 K, which is the relevant temperature range for hydrogen release from the hydrogenated LOHC compounds.

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“…It also meets the Department of Energy's storage requirement, with a storage capacity of 6.2%. It also meets all the previously stated safety criteria, such as non-toxicity and low flammability [9,[19][20][21].…”

Section: Naphthalene-decalin Systemmentioning

confidence: 71%

“…The dehydrogenation of perhydro-dibenzyl-toluene for hydrogen production was first reported by Bruckner et al in 2014 [22]. Since then, the DBT/PDBT pair has become the center of attention for many researchers [19,21,23,24]. Various researchers have conducted investigations for the identification of the characteristics of the dehydrogenation reaction conditions.…”

Section: Naphthalene-decalin Systemmentioning

confidence: 99%

Performance Analysis of the Perhydro-Dibenzyl-Toluene Dehydrogenation System—A Simulation Study

et al. 2021

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The depletion of conventional energy resources has drawn the world’s attention towards the use of alternate energy resources, which are not only efficient but sustainable as well. For this purpose, hydrogen is considered the fuel of the future. Liquid organic hydrogen carriers (LOHCs) have proved themselves as a potential option for the release and storage of hydrogen. The present study is aimed to analyze the performance of the perhydro-dibenzyl-toluene (PDBT) dehydrogenation system, for the release of hydrogen, under various operational conditions, i.e., temperature range of 270–320 °C, pressure range of 1–3 bar, and various platinum/palladium-based catalysts. For the operational system, the optimum operating conditions selected are 320 °C and 2 bar, and 2 wt. % Pt/Al2O3 as a suitable catalyst. The configuration is analyzed based on exergy analysis i.e., % exergy efficiency, and exergy destruction rate (kW), and two optimization strategies are developed using principles of process integration. Based on exergy analysis, strategy # 2, where the product’s heat is utilized to preheat the feed, and utilities consumption is minimized, is selected as the most suitable option for the dehydrogenation system. The process is simulated and optimized using Aspen HYSYS® V10.

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Thermophysical Studies of Dibenzyltoluene and Its Partially and Fully Hydrogenated Derivatives

Cited by 41 publications

References 31 publications

Hydrogen Production from the LOHC Perhydro-Dibenzyl-Toluene and Purification Using a 5 µm PdAg-Membrane in a Coupled Microstructured System

Hydrogen Production from the LOHC Perhydro-Dibenzyl-Toluene and Purification Using a 5 µm PdAg-Membrane in a Coupled Microstructured System

Thermal Conductivity of Hydrocarbon Liquid Organic Hydrogen Carrier Systems: Measurement and Prediction

Performance Analysis of the Perhydro-Dibenzyl-Toluene Dehydrogenation System—A Simulation Study

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