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New findings on CO2 adsorption on chitosan aerogels

Niemeyer, Philipp David and Ratke, Lorenz and Milow, Barbara (2020) New findings on CO2 adsorption on chitosan aerogels. Online Aerogel Seminar 2020, 16.-18. September 2020, Online (Hamburg, Deutschland).

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Abstract

Numerous publications describe amine groups bearing materials for selective CO2 separation. Most of those materials are of microporous nature. The Young-Laplace equation predicts CO2 condensation at 273 K in pores below 6 nm. Therefore it is of interest if the recorded CO2 adsorption isotherms show CO2 condensation in specific pores or reveal selective adsorption on surfaces. To overcome the question of condensation in pores or adsorption via amine groups we investigated mesoporous chitosan aerogel beads with a mean pore size of 40 nm. CO2 sorption isotherms were recorded at 273 K and 298 K, see Figure 1. The isotherm shape reveals partly irreversible adsorption reactions. The adsorption branch was recorded up to 100 kPa. The subsequent recorded desorption branch does not match the adsorption branch. A difference builds up between adsorption and desorption. At the end of desorption the starting and ending values do not match. Four different adsorption reactions are responsible for the CO2 sorption isotherms of chitosan aerogel beads. Those are: 1) covalent reaction according to the carbamate mechanism [RNHCO2]- + [RNH3]+, 2) charge\adsorptive interaction [RNHCO2\CO2]- and [RNH3\CO2]+, 3) dipole\adsorptive interaction ROH\CO2, and 4) non-specific London interaction #\CO2. Maximum adsorption capacities at 100 kPa of 1 mmol/g and 0.6 mmol/g were recorded at 273 K and 298 K respectively. At low CO2 absolute pressure of 0.25 kPa the adsorption capacities are 0.05 mmol/g and 0.03 mmol/g at 273 K and 298 K respectively. Microporous and amine group bearing materials published usually report adsorption capacities of at least one order of magnitude larger than those found in our studies. The comparison of adsorption capacities from mesoporous and amine bearing chitosan aerogels with microporous and amine bearing materials emphasizes the importance of micropores for selective CO2 separation due to pore condensation.

Item URL in elib:https://elib.dlr.de/138044/
Document Type:Conference or Workshop Item (Poster)
Title:New findings on CO2 adsorption on chitosan aerogels
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Niemeyer, Philipp DavidPhilipp.Niemeyer (at) dlr.dehttps://orcid.org/0000-0002-4386-2589
Ratke, Lorenzlorenz.ratke (at) dlr.dehttps://orcid.org/0000-0003-2487-4717
Milow, BarbaraBarbara.Milow (at) dlr.dehttps://orcid.org/0000-0002-6350-7728
Date:September 2020
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:chitosan aerogel, CO2 adsorption, chemisorption, physisorption, mesoporous adsorbent
Event Title:Online Aerogel Seminar 2020
Event Location:Online (Hamburg, Deutschland)
Event Type:international Conference
Event Dates:16.-18. September 2020
Organizer:Technische Universität Hamburg (TUHH)
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Transport System
DLR - Research area:Transport
DLR - Program:V VS - Verkehrssystem
DLR - Research theme (Project):V - Energie und Verkehr
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Aerogels and Aerogel Composites
Deposited By: Niemeyer, Philipp David
Deposited On:24 Nov 2020 16:49
Last Modified:24 Nov 2020 16:49

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