Comparison of by-product gas composition by activations of activated carbon

In this study, commercial activated carbons (ACs) were upgraded by different activation methods, and the gases generated during the activations were defined and quantified. The chemical activation commonly applied for upgrading ACs uses complex reactions, involving pyrolysis, physical, and chemical reactions. The ACs based on wood materials were characterized by elemental analysis, N2 physisorption, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and temperature-programmed desorption mass spectrometry. The patterns and composition of the generated gases were analyzed by gas chromatography and X-ray diffraction; high-resolution scanning electron microscopy was also used to characterize the activated carbon. The AC was mostly decomposed to CO2 by pyrolysis and physical activation, while CO was mainly detected during chemical activation from the K2CO3 produced by the reactions between CO2 and K2O. The detected amounts of generated gases were differed at various KOH ratios and residence times. The highest surface area obtained in this study was 2000 m2/g at the optimum ratio of AC and KOH (1:2).