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3D Printing of Activated Carbon and Exemplary Application as Adsorbent in the Electric Swing Adsorption

Steldinger, Hendryk (2020):
3D Printing of Activated Carbon and Exemplary Application as Adsorbent in the Electric Swing Adsorption. (Publisher's Version)
Darmstadt, Technische Universität,
DOI: 10.25534/tuprints-00011724,
[Ph.D. Thesis]

Abstract

Due to its tunable porosity and chemical versatility, activated carbon is one of the most widespread porous materials in industry used in applications such as adsorption and catalysis. Nevertheless, commercially available activated carbons suffer from low thermal and electric conductivity in the bulk, abrasion, and undefined bed porosity, since they are provided in the form of powders, pellets, or spherical particles. These obstacles could be overcome through the free design offered by 3D printing. However, present methods for the 3D printing of carbon either lack design freedom of the printed object or fail to introduce microporosity. In this work, a novel method for the 3D printing of carbon was developed. The method is based on lithographic 3D printing of a porous polymer, which is then transformed into activated carbon by a thermal treatment. Through the implementation of porogen templating into the printing process, meso- and macropores were introduced in the polymer precursor. In an optimized oxidation and pyrolysis procedure, the macrostructure and templated pores were retained and an additional fraction of micropores was introduced. Using CO2 activation the pore size was tailored and the specific surface area and pore volume increased to 2213 m²/g and 1.68 ml/g (QSDFT), respectively. These values are similar to those presented for activated carbons. Mechanical stability was maintained throughout the process. Through upscaling, activated carbon open-cellular monolithic structures of 40 mm in length and 20 mm in diameter were created. In an electric swing adsorption process, they exhibited a much better thermal and electric conductivity than a carbon pellet bed. Although the pelletized carbons showed a higher adsorption capacity because of a more densely packed bed, the monoliths could be regenerated much faster, due to their continuous macrostructure. The unique design flexibility of 3D printed carbons in combination with their top-notch porous properties will contribute to the optimization of industrial processes that rely on the use of activated carbons in the fields of adsorption, catalysis and energy application.

Item Type: Ph.D. Thesis
Erschienen: 2020
Creators: Steldinger, Hendryk
Status: Publisher's Version
Title: 3D Printing of Activated Carbon and Exemplary Application as Adsorbent in the Electric Swing Adsorption
Language: English
Abstract:

Due to its tunable porosity and chemical versatility, activated carbon is one of the most widespread porous materials in industry used in applications such as adsorption and catalysis. Nevertheless, commercially available activated carbons suffer from low thermal and electric conductivity in the bulk, abrasion, and undefined bed porosity, since they are provided in the form of powders, pellets, or spherical particles. These obstacles could be overcome through the free design offered by 3D printing. However, present methods for the 3D printing of carbon either lack design freedom of the printed object or fail to introduce microporosity. In this work, a novel method for the 3D printing of carbon was developed. The method is based on lithographic 3D printing of a porous polymer, which is then transformed into activated carbon by a thermal treatment. Through the implementation of porogen templating into the printing process, meso- and macropores were introduced in the polymer precursor. In an optimized oxidation and pyrolysis procedure, the macrostructure and templated pores were retained and an additional fraction of micropores was introduced. Using CO2 activation the pore size was tailored and the specific surface area and pore volume increased to 2213 m²/g and 1.68 ml/g (QSDFT), respectively. These values are similar to those presented for activated carbons. Mechanical stability was maintained throughout the process. Through upscaling, activated carbon open-cellular monolithic structures of 40 mm in length and 20 mm in diameter were created. In an electric swing adsorption process, they exhibited a much better thermal and electric conductivity than a carbon pellet bed. Although the pelletized carbons showed a higher adsorption capacity because of a more densely packed bed, the monoliths could be regenerated much faster, due to their continuous macrostructure. The unique design flexibility of 3D printed carbons in combination with their top-notch porous properties will contribute to the optimization of industrial processes that rely on the use of activated carbons in the fields of adsorption, catalysis and energy application.

Place of Publication: Darmstadt
Collation: XII, 95 Seiten
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Fachgebiet Technische Chemie
07 Department of Chemistry > Fachgebiet Technische Chemie > Technische Chemie I
Date Deposited: 16 Dec 2020 14:06
DOI: 10.25534/tuprints-00011724
Official URL: https://tuprints.ulb.tu-darmstadt.de/11724
URN: urn:nbn:de:tuda-tuprints-117243
Referees: Etzold, Prof. Dr. Bastian J. M. and Andrieu-Brunsen, Prof. Dr. Annette
Refereed / Verteidigung / mdl. Prüfung: 13 July 2020
Alternative Abstract:
Alternative abstract Language

In industriellen Adsorptionsverfahren ist Aktivkohle eines der am weitesten verbreiteten porösen Materialien. Es wird kommerziell hauptsächlich in Form von Pellets, Pulvers oder Kügelchen verkauft, weist daher jedoch einige Nachteile wie schlechte elektrische und Wärmeleitfähigkeit, Abrieb und verringerten Wandschüttdichten auf. Durch 3D Druck kann die Makrostruktur frei designt werden, um diese Nachteile zu überwinden. Jedoch mangelte es bisherigen 3D Druck Verfahren für Kohlenstoffen entweder an der mechanischen Stabilität, der erforderlichen Druckgenauigkeit, sodass nur rudimentäre Strukturen erzeugt wurden, oder es konnten keine Mikroporen erzeugt werden. In dieser Arbeit wurde eine neue Methode für den 3D Druck von Kohlenstoff auf der Basis der Umwandlung von lithographisch gedruckten porösen Polymeren entwickelt. Dafür wurde erstmals die Porogentemplierung mit der Photopolymerization in einem 3D Drucker kombiniert, um Polymere mit Meso- und Makroporen erzeugen. Durch ein optimiertes thermisches Verfahren ließen sich nicht nur die Makrostruktur und die templierten Poren erhalten, es wurde auch eine neue Fraktion von Mikroporen erzeugt. Durch CO2 Aktivierung konnte die Gesamtoberfläche auf 2213 m²/g und das Porenvolumen auf 1.68 ml/g (QSDFT) unter Erhalt der mechanischen Stabilität erhöht werden. Nach einem Upscaling war es möglich, offenzellige Monolithe bis zu einer Länge von 40 mm und einem Durchmessen von 20 mm zu drucken. Durch ihre kontinuierliche Struktur wiesen diese im Vergleich zu einer Kohlenstoffpelletschüttung eine deutlich erhöhte Wärmeleitfähigkeit auf. Auch wenn die Monolithe durch ihren höheren Hohlraumanteil in der Makrostruktur im Vergleich zur Pelletschüttung eine geringere Gesamtadsorptionskapazität aufwiesen, konnten sie deutlich schneller und zu einem höheren Grad in der Desorption regeneriert werden. Diese Methode des 3D Druckes von Aktivkohle ist daher geeignet, um durch ein gezieltes Design der Makrostruktur, Prozessintensivierung in den Anwendungsgebieten von Aktivkohle insbesondere bei zyklischen Adsorptionsprozessen zu erreichen.

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