Mechanism of CO2 capture in nanostructured sodium amide encapsulated in porous silica

Mi Tian, Antoine Buchard, Stephen A. Wells, Yanan Fang, Laura Torrente-Murciano, Antony Nearchou, Zhili Dong, Timothy J. White, Asel Sartbaeva*, Valeska P. Ting

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Nanostructured sodium amide encapsulated in a porous silica gel matrix (“NaNH2-SG”) was investigated for CO2 capture and storage by in-situ gravimetric gas sorption. Exposure of NaNH2-SG to CO2 at 25 °C and 1 bar pressure resulted in ~3.6 wt% CO2 uptake over eight sorption/desorption cycles. Over 90% of the CO2 uptake was non-reversible due to reaction between CO2 and NaNH2 to form sodium carbamate, as confirmed by 13C and 23Na solid-state NMR. Electronic structure calculations suggest a two-stage reaction process involving initial formation and subsequent rearrangement of the carbamate product. This research confirms the feasibility of sequential reactions of nanoparticles in a porous substrate (Na-SG to NaNH2-SG to Na-carbamate-SG), and of CO2 capture by NaNH2-SG nanoparticles stabilised by encapsulation within the porous substrate. This encapsulation method could allow further hygroscopic or reactive starting reagents or compounds to be explored for CO2 capture and long-term storage.

Original languageEnglish
Pages (from-to)227-233
Number of pages7
JournalSurface and Coatings Technology
Publication statusPublished - 25 Sept 2018
Externally publishedYes


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