γ‐Alumina Nanorod/Reduced Graphene Oxide as Support for Poly(ethylenimine) to Capture Carbon Dioxide from Flue Gas

Abstract

Abstract The synthesis of a mesoporous γ‐Al 2 O 3 nanorod/reduced graphene oxide (γ‐Al 2 O 3 NR/RGO) composite with a higher surface area and thermal conductivity than unmodified γ‐Al 2 O 3 has been accomplished, and these materials were characterized in detail. The composite was used successfully as a support for poly(ethylenimine) (PEI) to capture CO 2 at high temperature. The PEI‐modified composite (γ‐Al 2 O 3 NR/RGO/PEI) showed an excellent CO 2 adsorption from simulated flue gas at 75 °C and complete desorption at 100 °C with recyclability. The maximum CO 2 adsorption capacity of this material was 200.6 mg g PEI −1 (1.14 mmol CO 2 g adsorbent −1 ) with an amine efficiency of 0.22, which is higher than that of bare γ‐Al 2 O 3 /PEI. As a result of its high thermal conductivity, the overheating of the adsorbent during exothermic CO 2 adsorption by PEI was restricted and as a result the thermal degradation of PEI was prevented. Accordingly, the adsorption capacity of γ‐Al 2 O 3 NR/RGO/PEI does not deteriorate like that of bare γ‐Al 2 O 3 /PEI during repeated CO 2 adsorption–desorption cycles.