Effects of surface chemical properties of activated carbon fibers modified by HF treatment for CO2 adsorption

摘要

In the present work, TPD analysis was used to obtain a fundamental understanding of the role of the surface oxygen complexes on activated carbon fibers during adsorption processes. The required trends are that (a) a CO2 peak results from carboxylic acids at low temperatures or from lactones at high temperatures; (b) carboxylic anhydrides simultaneously generate a peak for CO and a peak for CO2; and (c) hydroxyls, ethers and carbonyls generate a CO peak [1,2]. Therefore, TPD analysis can be helpful in understanding the effects of the surface chemistry of activated carbon fibers containing hydroxyl and carboxyl groups on CO2 adsorption properties. The surface of poly- acrylonitrile (PAN)-based carbon fibers was activated by KOH and modified by liquid oxidation with hydrofluoric acid in various ratios for use as a CO2 adsorption material. The effects of the treatments on the surface morphology and the adsorption properties of the activated carbon fibers were also investigated. A mechanism is proposed for the improved CO2 adsorption efficiency of the activated carbon fibers after the liquid- oxidation treatment.