Abstract
ABSTRACT The use of an activated carbon (AC) with high ash content (15.92%) for SO2 removal was investigated during adsorption-desorption cycles. Significant deterioration in both dynamic and equilibria adsorption processes during the cycles was observed. To investigate the causes of deactivation, SO2 temperature-programmed desorption (SO2-TPD) experiments were conducted. The results indicated that most of the stored sulfur-containing species were released in the form of SO2 when the temperature was below 400°C. In addition to SO2, traces of CO were detected, but higher temperatures were required for the abundant release of CO. A Fourier-transform infrared spectrometry (FTIR) experiment was used to investigate changes in the oxygen-containing groups, and the results confirmed the formation of stable C-O complexes. These formations were tentatively attributed to the CO precursor’s occupation of active sites. Based on the formation of C-O complexes, two deactivation pathways in the cycles were proposed. The adsorption-desorption cycles also affected the AC ash. The formation of sulfur-containing species in the ash was confirmed through thermodynamic calculation and powder X-ray diffraction.
Highlights
SO2 resulting from fossil fuel combustion is a major source of air pollution, which contributes to the formation of acid rain
Zhang et al posited that C-O-C in ethers and C=O in quinones are the main active sites (Zhang et al, 2017), most researchers have inferred that bare carbon atoms located in edge positions are responsible for SO2 adsorption (Lizzio and DeBarr, 1996; Mochida et al, 1997; Mochida et al, 1999; Yang and Yang, 2003; Liu et al, 2016; Sun et al, 2016)
The findings revealed the effects of adsorption-desorption cycles on SO2 removal
Summary
SO2 resulting from fossil fuel combustion is a major source of air pollution, which contributes to the formation of acid rain. The activated carbon (AC)-based desulfurization process is categorized as dry FGD, which has attracted research attention because of its potential for use in converting SO2 into by-products of higher value, such as H2SO4 or S. This process requires relatively little or even no water, in contrast to conventional WFGD or semidry FGD; it is a suitable process for water-deficient areas (Gao et al, 2011a; Guo et al, 2015; Li et al, 2016). Lizzio and DeBarr (1996) demonstrated that SO2 adsorption does not exhibit a relationship with a specific area of AC, whereas Rubio and Izquierdo (1997)
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