Nitrogen-Enriched Porous Polyacrylonitrile-Based Carbon Fibers for CO₂ Capture

Abstract

Utilizing porous polyacrylonitrile (PAN) fibers as the precursors, porous carbon fibers were obtained by cross-linking of precursor fibers with hydrazine hydrate and subsequent heat treatment. A nitrogen content of more than 14 wt % was achieved in the carbon fibers. The porous carbon fiber that was prepared at low concentration of hydrazine hydrate (5 wt %) showed an optimal BET surface area of 277.4 m 2 /g with micro-/meso-/macropores. The CO 2 adsorbed amount of this porous carbon fiber was 101 mg/g at 25 °C under atmospheric pressure, which was 2.1 times that of the fiber without cross-linking with hydrazine hydrate. In the simulated flue gas environment (10% CO 2 /90% N 2 ), the adsorption capacity of the above-mentioned porous fiber was 32 mg/g at 25 °C, which was 1.4 times that of the fiber without cross-linking. These CO 2 adsorption results demonstrated that the nitrogen functionalities and porous structure of the porous carbon fiber played an equivalent important role in the adsorption of CO 2 . The porous carbon fiber also owned an excellent CO 2 reusability, and 96% of the adsorption capacity was maintained after 20 cycles of CO 2 adsorption and desorption. The porous carbon fibers enriched with nitrogen could thus be a potential material for CO 2 capture.

Effect of heat treatment temperature on CO2 capture of nitrogen‐enriched porous carbon fibers

“…In our previous work, as for PCF with no micropore and few meso‐/macropores, textural properties were considered to have little effect on the CO 2 capture. The CO 2 adsorbed on this PCF primarily originated from the chemical interaction between CO 2 and basic nitrogen‐containing groups in the fiber . Compared with the PCF previously reported, PCFs in this work show an improvement in the microporosity.…”

“…After about 5 min, a nearly complete removal of CO 2 adsorbed can be observed. When the work temperature was at 25°C, a portion of CO 2 remained in the PCFs . Though a lower CO 2 capacity is obtained at higher working temperature, the adsorbent can be recovered completely, which will be helpful for the next adsorption/desorption cycles.…”

“…Porous PAN fibers were prepared by phase separation with the assistance of PVP . Using AIBN as an initiator, AN and IA (98/2 wt/wt) were copolymerized in DMSO at 60°C for 22 h under nitrogen atmosphere, which was then precipitated in water, rinsed, and dried at 60°C in vacuum.…”

“…In our previous work, nitrogen‐enriched PCFs were obtained using porous PAN fibers as precursors . These precursors suffered cross‐linking with hydrazine hydrate (HH) and subsequent heat treatment.…”

“…This work focuses on the CO 2 adsorption of PCFs prepared by the variation of the temperatures of oxidation and carbonization. Porous PAN fibers were cross‐linked by HH before oxidation as previously reported . The change of the elements and porous structure with heat treatment temperature was followed.…”