Optimization of membrane area to catalyst mass in a microstructured membrane reactor for dehydrogenation of methylcyclohexane

Cholewa, Martin; Zehner, Bastian; Kreuder, H.; Pfeifer, Peter

doi:10.1016/j.cep.2017.10.011

Cited by 13 publications

(13 citation statements)

References 39 publications

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“…The microstructured membrane separation module used (see Figure 4) has already been presented in previous work [18,20,21]. The module consists of a total of five elements-a 5 µm thick PdAg foil is mechanically stabilized with stainless steel micro sieves on each side, and placed between two foils with 17 micro channels (length × height × width: 4 cm × 300 µm × 500 µm) and welded together with laser technology.…”

Section: Membrane Separatormentioning

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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Section: Membrane Separatormentioning

confidence: 99%

“…The used 5 µm PdAg membrane is mechanically stabilized by two micro sieves and integrated between two foils with micro channels. The stack is then bonded by laser welding[21].…”

mentioning

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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“…A membrane module with 17 microchannels (width × depth × length: 500 µm × 300 µm × 4 cm), which was described in detail in References [9,16], was used as separation device (see Figure 4). The used PdAg membrane was produced by SINTEF/Oslo via magnetron sputtering and has a thickness of approximately 10 µm.…”

Section: Methodsmentioning

confidence: 99%

“…Micro-process engineering offers two promising approaches—the use of a micro-structured reactor allows an almost isothermal reaction environment, which prevents “cold spots” by limited heat input. Furthermore, it has already been shown that Pd-based membranes benefit from a micro-structured environment to separate hydrogen with high efficiency and purity from a gas mixture [9,10,11,12,13,14,15,16]. The combination of membrane and reaction in microreactors has been demonstrated as highly beneficial over conventional systems in these studies.…”

Section: Introductionmentioning

confidence: 99%

“…According to our calculations with already applied membrane modules [16], considering the relatively low concentrations of other components in the gas phase of a separation at low reaction pressures (4–5 bar (a)) is feasible and the disadvantage of the shifted reaction equilibrium is, therefore, acceptable. In this work, the micro-structured multi-stage reactor concept with intermediate hydrogen separation (schematically shown in Figure 1) is modelled based on experimental data of the reactor and membrane separator.…”

Section: Introductionmentioning

confidence: 99%

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Intensified LOHC-Dehydrogenation Using Multi-Stage Microstructures and Pd-Based Membranes

Wunsch¹,

Mohr²,

Pfeifer³

2018

Membranes

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Liquid organic hydrogen carriers (LOHC) are able to store hydrogen stably and safely in liquid form. The carrier can be loaded or unloaded with hydrogen via catalytic reactions. However, the release reaction brings certain challenges. In addition to an enormous heat requirement, the released hydrogen is contaminated by traces of evaporated LOHC and by-products. Micro process engineering offers a promising approach to meet these challenges. In this paper, a micro-structured multi-stage reactor concept with an intermediate separation of hydrogen is presented for the application of perhydro-dibenzyltoluene dehydrogenation. Each reactor stage consists of a micro-structured radial flow reactor designed for multi-phase flow of LOHC and released hydrogen. The hydrogen is separated from the reactors’ gas phase effluent via PdAg-membranes, which are integrated into a micro-structured environment. Separate experiments were carried out to describe the kinetics of the reaction and the separation ability of the membrane. A model was developed, which was fed with these data to demonstrate the influence of intermediate separation on the efficiency of LOHC dehydrogenation.

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Microstructured membrane reactors for process intensification

Gapp

Ansaloni

Venvik

et al. 2023

Current Trends and Future Developments on (Bio)Membranes

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Optimization of membrane area to catalyst mass in a microstructured membrane reactor for dehydrogenation of methylcyclohexane

Cited by 13 publications

References 39 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

Intensified LOHC-Dehydrogenation Using Multi-Stage Microstructures and Pd-Based Membranes

Microstructured membrane reactors for process intensification

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