Rational synthesis of microporous carbons for enhanced post-combustion CO2 capture via non-hydroxide activation of air carbonised biomass

Altwala, Afnan; Mokaya, Robert

Abstract

This work explores the use of a less corrosive activating agent, potassium oxalate (PO), in combination with difficult to activate carbonaceous matter for the preparation of activated carbons. The design of the study allowed a fuller understanding of the workings of PO compared to hydroxide (KOH) activation, and also optimised the preparation of highly microporous carbons with exceptional CO2 storage capacity under low pressure (≤1 bar) conditions at ambient temperature. The PO activated carbons have a surface area of up to 1760 m2 g−1 and are highly microporous with virtually all of the surface area arising from micropores. The porosity of the PO activated carbons can be readily tailored towards having pores of size 6-8 Å, which are highly suited for CO2 storage at low pressure (i.e., post-combustion capture). At 25 °C, the PO activated carbons can store up to 1.8 and 5.0 mmol g−1 of CO2 at 0.15 bar and 1 bar, respectively. On the other hand, KOH activated carbons reach a higher surface area of up to 2700 m2 g−1, and store up to 1.0 and 4.0 mmol g−1 of CO2. This work demonstrates that PO may be used as a mild, less corrosive and less toxic activating agent for the rational and targeted synthesis of biomass-derived activated carbons with tailored porosity. The targeted synthesis may be aided by careful selection of the biomass starting material as guided by the O/C ratio of the biomass.

Citation

Altwala, A., & Mokaya, R. (2022). Rational synthesis of microporous carbons for enhanced post-combustion CO2 capture via non-hydroxide activation of air carbonised biomass. RSC Advances, 12(31), 20080-20087. https://doi.org/10.1039/d2ra02661a

• Journal Article Type: Article
• Acceptance Date: Jul 5, 2022
• Online Publication Date: Jul 12, 2022
• Publication Date: Jul 12, 2022
• Deposit Date: Aug 16, 2022
• Publicly Available Date: Aug 16, 2022
• Journal: RSC Advances
• Electronic ISSN: 2046-2069
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 31
• Pages: 20080-20087
• DOI: https://doi.org/10.1039/d2ra02661a
• Keywords: General Chemical Engineering; General Chemistry
• Public URL: https://nottingham-repository.worktribe.com/output/8955898
• Publisher URL: https://pubs.rsc.org/en/content/articlelanding/2022/RA/D2RA02661A