Porous Organic Polymers Constructed from Tröger's Base as Efficient Carbon Dioxide Adsorbents and Heterogeneous Catalysts

Preparation of heteroatom-doped hyper-crosslinked polymers via waste utilization of sulfur-containing petroleum coke: A promising adsorbent for CO2 capture

To overcome the worldwide environmental crisis related to the continuous emission of CO2, the use of porous organic polymers, which are excellent absorbents and conversion materials, to reduce CO2 emission is of great significance. Among them, hyper-crosslinked polymers (HCPs) are porous materials with a high pore density that are synthesized using a simple one-pot method that is economical and can realized at a low temperature, hence they have good application prospects as adsorbents for CO2. In this study, a batch of petroleum coke-based HCPs with different sulfur contents was prepared via the one-pot Friedel-Crafts alkylation reaction using inexpensive and abundant petroleum coke as raw material. Thereafter, the use of the prepared materials for CO2 adsorption revealed that the HCPs with a high sulfur content had a larger specific surface area (825 m2/g) and showed a higher CO2 adsorption capacity (2.1603 mmol/g at 1 bar 298 K) than its counterpart with a lower sulfur content. Thus, the presence of sulfur significantly enhanced the CO2 adsorption performance of the material. Further, the simulation of the heat of adsorption of HCPs with and without sulfur using Material Studio also confirmed the higher CO2 capture efficacy of HCPs with a higher sulfur content.

Preparation of a Solid Amine Microspherical Adsorbent with High CO2 Adsorption Capacity

Amine-skeleton solid-amine materials are promising adsorbents for CO₂ capture from flue gas. Here, a novel solid-amine microsphere was synthesized by cross-linking the skeleton poly(ethylenimine) (PEI) with ethylene glycol diglycidyl ether in a facile one-pot W/O emulsion system. The material had a remarkable CO₂ adsorption capacity of 7.28 mmol/g in the presence of moisture at 20 °C, 0.1 bar. The highest ratio of breakthrough capacity to saturation capacity was ca. 84%. According to kinetic simulation, the Avrami kinetic model could better describe the adsorption process of CO₂ under different temperatures, in which the value of R² was above 0.99 and n was between 1 and 2, indicating that both physical and chemical adsorption mechanisms were performed during adsorption. Moreover, the material had a high swelling speed. Equilibrium was established within 30 s, and the swelling ratio was 271% at equilibrium. The saturated adsorbent could be easily regenerated with a regeneration efficiency of 94.63% after six cycles. The PEI microsphere appears to be a promising candidate material for CO₂ capture from flue gas.