Significantly Increased CO2 Adsorption Performance of Nanostructured Templated Carbon by Tuning Surface Area and Nitrogen Doping

J. Phys. Chem. C, 2012, 116 (1), pp 1099–1106

Significantly Increased CO₂ Adsorption Performance of Nanostructured Templated Carbon by Tuning Surface Area and Nitrogen Doping

Lifeng Wang and Ralph T. Yang*

yang@umich.edu

Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States

Abstract

Describes a systematic study of carbon dioxide adsorption properties of a series of templated carbon adsorbents with high Brunauer–Emmett–Teller surface areas  and with/without nitrogen doping.

Initially, two linear relationships between CO₂ adsorption capacities and surface areas of nitrogen-doped/undoped nanostructured templated carbons were established. The doped nitrogen was present in the forms of pyridinic nitrogen, pyrrolic/pyridonic nitrogen, quaternary nitrogen, and an oxidized form of nitrogen. The interaction energies with CO₂, as approximated by the isosteric heats of adsorption, were increased from 30 kJ/mol on the undoped carbon to 50 kJ/mol on the N-doped carbon as a result of these nitrogen sites. The increased interactions led to an enhancement in CO₂ adsorption capacity by a factor of 2, while N₂ uptake was not enhanced. The optimized N-doped templated carbon, N-TC-EMC, possessed remarkable CO₂ capacity  and selectivity. Postdoping ammonia treatment was found beneficial to CO₂ adsorption. CO₂ performance of N-doped carbon under wet condition and conditions relevant to flue gas, rates of adsorption, and regeneration requirement, which are important for practical applications, were also investigated. The results showed that N-doped templated carbon exhibited all prerequisite attributes for CO₂ capture and storage applications: high CO₂ capacity and CO₂/N₂ selectivity, fast and reversible adsorption, thermal and moisture stabilities, and ease in CO₂ desorption.

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