Preparation and Characterization of a Solid Amine Adsorbent for Capturing CO2 by Grafting Allylamine onto PAN Fiber

Abstract

Solid amine adsorbents using synthetic fibers instead of silica as the matrix are expected to offer more benefits for the adsorption of CO₂ because of high external surface area, low pressure drops, and flexibility of the matrix fibers. A novel kind of solid amine-containing fibrous adsorbent (PAN-AF) was prepared by preirradiation grafting copolymerization of allylamine onto polyacrylonitrile (PAN) fiber, using the redox system of (NH₄)₂S₂O₈/NaHSO₃ as initiator. The effects of the reaction conditions such as reaction time, temperature, monomer concentration, amount of the initiator on grafting degree were studied. The results showed that the optimal conditions for the grafting copolymerization were using 50% allylamine monomer (V/V) and 1.5% (W/V) initiator and reacting at 100 °C for 10 h. FTIR was employed to characterize the corresponding changes on the surface chemical structure of PAN and PAN-AF. Thermal gravimetric analysis was used to evaluate the thermal stability of the materials. Equilibrium adsorption capacities for CO₂ and regeneration behaviors of PAN-AF were determined. Adsorption capacity for CO₂ of PAN-AF with 60.0 wt % grafting degree was 6.22 mmol CO₂/g PAN-AF. PAN-AF could be completely regenerated by heating in boiling water for 30 min. The CO₂ adsorption performance of the regenerated PAN-AF was almost the same as that of the fresh adsorbent after several cycles, which revealed that PAN-AF exhibited good regenerating stability. The high speed and effective regeneration process proves that PAN-AF has great potential in industrial applications for CO₂ capture.