Sustainable CO2 Capture: N,S-Codoped Porous Carbons Derived from Petroleum Coke with High Selectivity and Stability
Jiawei Shao, Yingyi Wang, Mingyang Che, Ya Liu, Yongfu Jiang, Qiang Xiao, Müslüm Demir, Linlin Wang, Xin Hu
Abstract
CO2 capture from the flue gas is a promising approach to mitigate global warming. However, regulating the carbon-based adsorbent in terms of textural and surface modification is still a challenge. To overcome this issue, the present study depicts the development of cost-effective and high-performance CO2 adsorbents derived from petroleum coke, an industrial by-product, using a two-step process involving thiourea modification and KOH activation. A series of N,S-codoped porous carbons was synthesized by varying activation temperatures and KOH quantity. The optimized sample exhibited a high specific surface area of 1088 m2/g, a narrow micropore volume of 0.52 cm3/g, and considerable heteroatom doping (1.57 at.% nitrogen and 0.19 at.% sulfur). The as-prepared adsorbent achieved a CO2 adsorption capacity of 3.69 and 5.08 mmol/g at 1 bar, 25 °C and 0 °C, respectively, along with a CO2/N2 selectivity of 17. Adsorption kinetics showed 90% of equilibrium uptake was achieved within 5 min, while cyclic studies revealed excellent stability with 97% capacity retention after five cycles. Thermodynamic analysis indicated moderate isosteric heat of adsorption (Qst) values ranging from 18 to 47 kJ/mol, ensuring both strong adsorption and efficient desorption. These findings highlight the potential of petroleum coke-derived porous carbons for sustainable and efficient CO2 capture applications.