Siliceous nanosphere material for CO2 capture: Kinetics, isotherm, and multicyclic performance studies

Abstract

In this work, novel, fibrous-shaped siliceous nanosphere KAUST Catalysis Center-1 (KCC-1) material is synthesized, characterized, and functionalized using different weight percentages of polyethyleneamine for post-combustion carbon dioxide (CO₂) capture. To study the structural properties, various characterization methods, such as field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), nitrogen adsorption/desorption isotherms, and powder X-ray diffraction (PXRD), are used. Morphological studies reveal the fibrous structure of the synthesized KCC-1 with an average pore size of 3.50 nm and a high specific surface area of 561.13 m²/g. The CO₂ capture capacity experiments are investigated using the thermogravimetric method. With an optimized amine loading of 60 wt.% and an adsorption temperature of 75°C, the equilibrium CO₂ uptake capacity is 2.90 mmol CO₂/g. From the 27 consecutive temperature swing adsorption/regeneration cycles, it is found that the working CO₂ capacity of the sorbent decreases marginally (only 4.80%) and remains nearly stable at about 2.59 mmol CO₂/g. Finally, the kinetic and isothermal modelling suggest that the kinetics of CO₂ capture is best described by the pseudo-fractional order model with a deviation of less than 3.62% from experimental data when the adsorption temperature is 75°C, while the modified Toth model is found to best fit the isotherm data with a deviation of less than 2.76% from experimental findings.