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High-Performance Magnetic Activated Carbon from Solid Waste from Lignin Conversion Processes. 1. Their Use As Adsorbents for CO2
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
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Number of Authors: 72017 (English)In: Acs Sustainable Chemistry and Engineering, ISSN 2168-0485, Vol. 5, no 4, p. 3087-3095Article in journal (Refereed) Published
Abstract [en]

Lignin is naturally abundant and a renewable [GRAPHICS] precursor with the potential to be used in the production of both chemicals and materials. As many lignin conversion processes suffer from a significant production of solid wastes in the form of hydrochars, this study focused on transforming hydrochars into magnetic activated carbons (MAC). The hydrochars were produced via hydrothermal treatment of lignins together with formic acid. The activation of the hydrochars was performed chemically with KOH with a focus on the optimization of the MACs as adsorbents for CO2. MACs are potentially relevant to carbon capture and storage (CCS) and gas purification processes. In general, the MACs had high specific surface areas (up to 2875 m(2)/g), high specific pore volumes, and CO2 adsorption capacities of up to 6.0 mmol/g (I atm, 0 degrees C). The textual properties of the MACs depended on the temperature of the activation. MACs activated at a temperature of 700 degrees C had very high ultramicropore volumes, which are relevant for potential adsorption-driven separation of CO2 from N-2. Activation at 800 degrees C led to MACs with larger pores and very high specific surface areas. This temperature-dependent optimization option, combined with the magnetic properties, provided numerous potential applications of the MACs besides those of CCS. The hydrochar was derived from eucalyptus lignin, and the corresponding MACs displayed soft magnetic behavior with coercivities of <100 Oe and saturation magnetization values of 1-10 emu/g.

Place, publisher, year, edition, pages
2017. Vol. 5, no 4, p. 3087-3095
Keywords [en]
CCS, Magnetic activated carbon, Lignin conversion, Hydrochar, Separation, Adsorption, Desorption
National Category
Chemical Sciences Chemical Engineering
Research subject
Materials Chemistry
Identifiers
URN: urn:nbn:se:su:diva-142383DOI: 10.1021/acssuschemeng.6b02795ISI: 000398429700034OAI: oai:DiVA.org:su-142383DiVA, id: diva2:1092989
Available from: 2017-05-04 Created: 2017-05-04 Last updated: 2019-02-22Bibliographically approved
In thesis
1. Sustainable porous organic materials: Synthesis, sorption properties and characterization
Open this publication in new window or tab >>Sustainable porous organic materials: Synthesis, sorption properties and characterization
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The resources available to us humans, including metals, minerals, biomass, air, water, and anything else on the planet, are being used at an increasing rate. This anthropogenic use of resources both depletes the resources and has negative impacts on other resources, e.g. the biosphere. Thus, developing (more) sustainable chemical and industrial processes are of the utmost importance for the well-being of the creatures of Earth and for the long-term sustainability of human society.

This thesis focuses on organic porous materials, and more specifically their synthesis and characterization. Porous materials are, for example, used in detergents, water treatment, bio gas upgrading, carbon dioxide capture, as catalysts, in sensors, and in various biological applications. The application of porous materials can contribute to the drive towards a more sustainable society. However, porous materials are typically not sustainable themselves. Thus, there is a need to develop more sustainable porous materials. The synthesis and characterization of three different groups of porous organic materials are described in this thesis.

In pulp- and paper manufacturing, lignin is separated from desirable products and is typically combusted for heat. In one section of this thesis, lignin was used to produce bio-oil for potential use in fuels and chemicals. However, the bio-oil process produced a solid by-product. The by-product was used to synthesize and study activated carbons with very high porosities and magnetic properties, a combination of properties that may prove to be useful in applications.

Sugar is known to produce solid and unwanted compounds through reactions with acids. It is shown here that it is possible to produce highly microporous humins, i.e. organic porous materials with a large amount of small pores, using sulphuric acid and a range of saccharides and bio-based polymers. This work supports that solid by-products in a wide range of biomass conversion processes can be of high value, both economically and as replacements for less sustainable alternatives.

The biosphere contains vast amounts of molecules with aromatic structures. The last section of this thesis shows how such aromatic molecules can be used to produce highly porous materials through Friedel-Crafts type chemistry using sulfolane as a solvent and iron chloride as a catalyst. This synthesis strategy produces high-performance materials, improves upon the sustainability of traditional Friedel-Crafts chemistry, and makes use of typically underutilized and abundant bio-based molecules.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry, Stockholm University, 2018. p. 64
Keywords
porous materials, sorbents, microporous, CO2 capture and separation, gas adsorption, activated carbon, humins, hypercrosslinked polymers, sustainable
National Category
Materials Chemistry
Research subject
Materials Chemistry
Identifiers
urn:nbn:se:su:diva-159468 (URN)978-91-7797-428-4 (ISBN)978-91-7797-429-1 (ISBN)
Public defence
2018-10-29, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2018-10-04 Created: 2018-08-30 Last updated: 2018-09-27Bibliographically approved

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