Preparation and CO2 adsorption properties of TEPA-functionalized multi-level porous particles based on solid waste.

In this paper, tetraethylenepentamine (TEPA)-functionalized solid waste-based porous particles were prepared by the wet impregnation method, and their functionalization characteristics and CO 2 adsorption performances at different TEPA loadings were investigated. Through a scanning electron microscope test and a N 2 adsorption/desorption test, it is found that, as the TEPA loading increases from 4 wt% to 20 wt%, the specific surface area and pore volume of the samples decrease slowly and micropores gradually disappear. Besides, the CO 2 adsorption capacity of the samples was tested by a fixed-bed adsorption experimental device at 298 K and 0–1 bar. The results show that the CO 2 adsorption capacity reaches the maximum (71.29 mg/g) at a 12 wt% TEPA loading, which is attributed to the high content of affinity sites in CO 2. Furthermore, the effect of temperature (298–398 K) was investigated at 1 bar. It is concluded that an appropriate increase in adsorption temperature can enhance the flexibility of TEPA and greatly reduce its diffusion resistance. The highest adsorption capacity (83.05 mg/g) is achieved at 348 K. Then, the effect of pressure (0–40 bar) was analyzed at the optimal temperature (348 K) and optimal TEPA loading (12 wt%), and the results suggest that the adsorption capacity gradually strengthens with the increase in pressure, ultimately reaching a peak of 204.06 mg/g. The adsorption selectivities of CO 2 /N 2 and CO 2 /H 2 are 14.88 and 9.66, respectively, indicating that the porous particles have a stronger affinity for CO 2 than for N 2 and H 2. The infrared spectra prove the formation of carbamates, which confirms that CO 2 is sequestered in porous particles by chemical adsorption. The adsorption kinetics and adsorption thermodynamics results reveal the presence of both physical and chemical adsorptions of 12 wt% TEPA-porous particles in the adsorption process, and the chemical one is dominant. [Display omitted] [ABSTRACT FROM AUTHOR]