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Synthesis of millimeter‑sized porous carbon spheres derived from different precursors for ­CO2 capture Changming Zhang1,2 · Rongxian Wang3 · Yaqi Wang3 · Guangmin Ren3 · Xiaochao Zhang3 · Rui Li3 · Caimei Fan3

© Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract Activated carbon spheres (ACSs) with high surface area and controlled microporous structure were prepared from alkyl phenols and formaldehyde via suspension polymerization and steam activation. The effects of different phenolic resin precursors to ACSs on the textural structure and C ­ O2 adsorption capacity were investigated. The pyrolysis behavior and surface chemistry of the alkyl phenolic resin spheres were characterized by thermal gravimetric, FTIR, XRD and XPS. The texture properties of the obtained ACSs were characterized by ­N2 adsorption–desorption and scanning electron microscope (SEM). Results showed that the as-prepared ACSs were basically microporous, and exhibited a surface area value as high as 1803.44 ­m2/g and a total pore volume of 0.96 c­ m3/g. The maximum C ­ O2 adsorption capacity of the ACSs can reach 4.53 mmol/g and 13.62 mmol/g at 25 °C under 1 bar and 6 bar. The ­CO2 adsorption capacity had a good linear correlation with the micropore volume at higher pressures. The thermodynamic parameters indicate that physical adsorption mechanisms for ­CO2 adsorption mainly exist in the ACSs. In addition, the prepared ACSs are easily regenerated and shows a great recycling stability after multiple cycles. Keywords  Alkylphenol resin · Activated carbon spheres · CO2 adsorption · Cyclic stability

1 Introduction It is widely accepted that carbon dioxide (­ CO2) resulting from the fossil fuel combustion releases into the atmosphere and gives rise to global warming and climate change, and it has been defined as one of the most important greenhouse gases [1–4]. Therefore, more research activities related to developing efficient technologies have been exploited to capture ­CO2. For example, the most mature ­CO2 capture technology is absorption by means of amine solutions in commercial applications, but it has serious drawbacks, such as * Changming Zhang [email protected] * Xiaochao Zhang [email protected] 1



College of Mining Engineering, Taiyuan University of Technology, Taiyuan 030024, People’s Republic of China

2



Shanxi Communications Technology R & D Co., Ltd, Taiyuan 030024, People’s Republic of China

3

College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, People’s Republic of China



high energy requirement and corrosion of process equipment [5]. Therefore, extensive research is carried out to propose alternative technologies to capture ­CO2, such as adsorption, membrane separation and cryogenic distillation. Adsorption shows many potential advantages over other separation techniques, such as reduced energy for regeneration, great selectivity and ease of handling [6–8], has been proposed for ­CO2 capture by using porous solids such as silica gel, z