CO2 Uptake By Microporous Carbon Aerogels Derived From Polybenzoxazine And Analogous All-Nitrogen Polybenzodiazine Aerogels

Author

Vaibhav A. Edlabadkar
Rushi U. Soni
A. B.M.Shaheen ud Doulah
Stephen Y. Owusu
Samuel Hackett
Joshua M. Bartels
Nicholas Leventis, Missouri University of Science and TechnologyFollow
Chariklia Sotiriou-Leventis, Missouri University of Science and TechnologyFollow

Abstract

The rapid rise of carbon dioxide in the atmosphere contributes to global warming and ocean acidification. Carbon capture is considered essential for keeping the atmospheric CO₂ levels from rising further. This work addresses the question of whether nitrogen or oxygen lining of the surfaces of carbon-based CO₂ absorbers is more efficient for CO₂ capture. Polybenzodiazine (PBDAZ) aerogels are carbon-aerogel precursors that were prepared recently (2023) as all-nitrogen structural analogues to well-known polybenzoxazine (PBO) aerogels. However, owing to the fact that the carbonization chemistries of both PBO and PBDAZ aerogels require a prior oxidative aromatization step in air at around 200-240 °C, both types of the resulting carbon (C) aerogels contained both oxygen and nitrogen in their structures. As a carryover from their polymeric aerogel precursors, C-PBDAZ aerogels included a higher weight percent of N (7-11%) relative to the C-PBO aerogels (5.2-5.7%) while both types of carbons included about the same amount of O (7-9%). Activation (etching) with CO₂ at 1000 °C removed more N than O, so the resulting etched carbon aerogels from either source (EC-PBDAZ or EC-PBO) contained about 8-9% of O and only 3.0-3.6% N. Postetching, most oxygen was situated in pyridonic and nitroxide sites (by XPS). Looking at the PBDAZ- and PBO-derived C and EC aerogels independently, whenever processing increased the O/N ratio within each material, the CO₂ uptake (at 273 K, 1 bar) also increased, reaching 11.5 mmol g-1 in EC-PBDAZ and 4.6 mmol g-1 in EC-PBO aerogels, starting from 7.0 mmol g-1 by C-PBDAZ and 3.0 mmol g-1 by C-PBO. Subsequently, by eliminating the relative pore volumes and surface areas as causing the different CO₂ uptakes by the two types of materials, the highest CO₂ uptake by the EC-PBDAZ aerogels was attributed to the pore sizes (diameters in the 3-4 nm range) in combination with the geometry of the CO2-surface adducts. EC-PBDAZ carbon aerogels showed high selectivity for CO₂ versus H₂ (up to 404:1─relevant to precombustion CO₂ capture) and high selectivity for CO₂ versus N₂ (up to 48:1─relevant to post combustion CO₂ capture).

Recommended Citation

V. A. Edlabadkar et al., "CO2 Uptake By Microporous Carbon Aerogels Derived From Polybenzoxazine And Analogous All-Nitrogen Polybenzodiazine Aerogels," Chemistry of Materials, vol. 36, no. 3, pp. 1172 - 1187, American Chemical Society, Feb 2024.

The definitive version is available at https://doi.org/10.1021/acs.chemmater.3c01717

Department(s)

Chemistry

Comments

National Science Foundation, Grant CMMI-1530603

International Standard Serial Number (ISSN)

1520-5002; 0897-4756

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Chemical Society, All rights reserved.

Publication Date

13 Feb 2024