(506g) Preparation and Its Excellent CO2/CH4/N2 Adsorption Selectivity of Novel Carbon Composites CPDA@A-ACs

Preparation
and Its Excellent CO₂/CH₄/N₂ Adsorption
Selectivity of Novel Carbon
Composites CPDA@A-ACs

Wanwen
Liang, Huiyu Xiao, Zhong Li*

School of Chemistry and
Chemical Engineering, South
China University of Technology, Guangzhou 510640,
PR China

*Corresponding author e-mail
address: cezhli@scut.edu.cn

Abstract

In this work, novel
composites (CPDA@A-ACs) of carbonized polydopamine (CPDA) and asphalt-based
activated carbons (A-ACs) were successfully synthesized. The resulting
CPDA@A-ACs were characterized, and the CO₂/CH₄/N₂
adsorption isotherms of CPDA@A-ACs were measured separately. The isosteric
heats of CO₂/CH₄/N₂ adsorption on the samples
were estimated. The dynamic separation performances of the samples for CO₂/N₂
and CO₂/CH₄ binary mixtures were evaluated in fixed-bed breakthrough
experiments. Results showed that BET area and total pore volume of CPDA@A-ACs
were up to 1971 m²/g and 0.79 cm³/g, respectively. The N
contents and the concentration of basic sites on CPDA@A-ACs are higher than
those on parent A-AC due to the introduction of CPDA. CPDA@A-ACs possessed not
only excellent stability, but also excellent CO₂ adsorption capacity
up to 4.05 mmol/g and 6.89 mmol/g at 298 K and 273 K, respectively, at ambient
pressure, much higher than the parent A-AC, most of the reported porous carbon
materials and many reported metal-organic frameworks (MOFs) for CO₂
capture under identical conditions. More importantly, CPDA@A-ACs possessed
excellent adsorption selectivity toward CO₂/N₂ and CO₂/CH₄
binary mixtures. Its IAST-predicted selectivity
at normal pressure and temperature reached as high as 25 for CO₂/N₂
(0.15/0.85) mixture and 5 for CO₂/CH₄ (0.5/0.5) mixture
separately. Fixed-bed experiments showed that the CO₂/N₂ (0.15/0.85)
mixture and CO₂/CH₄ (0.5/0.5) mixture can be well
separated at room temperature, suggesting great potential for industrial CO₂/N₂
and CO₂/CH₄ separation.

Keywords:
Asphalt, Polydopamine, CO₂
adsorption, CO₂/CH₄/N₂ selectivity