Carbon consumption and regeneration of oxygen-containing functional groups on activated carbon for flue gas purification

Abstract

High carbon consumption is an important factor restricting the wide application of activated carbon technology for flue gas purification. A fixed-bed reactor combined with a Fourier transform infrared (FTIR) spectrometer was used to explore the source of carbon consumption at various SO 2 concentrations and cyclic adsorption-regeneration times. The results demonstrate that carbon consumption originates from two sources and is mainly determined by the reaction of H 2 SO 4 and C at high SO 2 concentrations and by the thermal decomposition of oxygen-containing functional groups at low SO 2 concentrations. An interesting observed phenomenon is that carbon consumption does not increase as the SO 2 concentration increases. The conversion mechanism reveals that carboxylic and anhydride groups are converted to phenol and quinone groups, which do not easily decompose with increasing SO 2 concentration. In the process of cyclic adsorption-regeneration, it is discovered that the carbon consumption in the first cycle is several times higher than that in the following cycles due to the decomposition of functional groups from the activated carbon itself. The regeneration mechanism of functional groups has been elucidated. The carboxylic acid and the phenolic hydroxyl on the surface of activated carbon are consumed in the regeneration process and formed again from the conversion of carbonyl groups in the next adsorption process under the roles of O 2 and H 2 O. It is proposed that the functional groups are regenerated in the adsorption process rather than in the regeneration process. Keywords Activated carbon • Carbon consumption • Cyclic adsorption-regeneration • Decomposition of functional groups • Carbon dioxide Highlights• Carbon consumption does not increase as the SO 2 concentration increases because carboxylic and anhydride groups are converted to phenol and quinone groups which do not easily decompose.• The carboxylic acid and the phenolic hydroxyl are consumed in the regeneration process and formed again from the conversion of carbonyl groups in the next adsorption process under the roles of O 2 and H 2 O.• The source of carbon consumption is revealed, and transformation path of functional groups is proposed.

SO2 Adsorption and Kinetics Analysis during Supported Triethanolamine Acetate Ionic Liquid Desulfurization

“…The sulfur capacity of TAIL/SiO 2 is 89.36 mg/(g TAIL/SiO 2 ), while that of “Zhuxi” and “Sinopharm” activated carbons is only 30.94 mg/(g AC) and 16.63 mg/(g AC) respectively. Notably, many researchers have tested the adsorption and regeneration performances of activated carbon for SO 2 . ,, …”

“…Notably, many researchers have tested the adsorption and regeneration performances of activated carbon for SO 2 . 13 , 57 , 58 …”

“…In addition, treatment and utilization of byproducts have been challenging. , Hence, their large-scale development and application are gradually being restricted by limited resources and environmental considerations. In particular, activated carbon has received considerable attention for application in flue-gas desulfurization. , Although activated carbon desulfurization technology is simple and the product can be regenerated, activated carbon has inherent disadvantages (e.g., low sulfur capacity and large regeneration loss). , Therefore, a high-efficiency and high-sulfur-capacity desulfurization technology that can be recycled after use should be developed.…”

“… 11 , 12 Although activated carbon desulfurization technology is simple and the product can be regenerated, activated carbon has inherent disadvantages (e.g., low sulfur capacity and large regeneration loss). 13 , 14 Therefore, a high-efficiency and high-sulfur-capacity desulfurization technology that can be recycled after use should be developed.…”

Synthesis and Characterization of MOF‐Derived Structures: Recent Advances and Future Perspectives

“…[392,393] Additionally, DRIFTS enables the study of MOF behaviour under different temperatures or in the presence of specific gases like CO and CO 2. [394] For example, to understand how CO 2 adsorbed on the basic sites of MOF-808a, the DRIFTS test has been performed (Figure 39). [344] Although there is a probability of interference between IR spectra of the carboxylate group of the BTC ligand in MOF-808a with IR observation of CO 2 adsorption on MOF-808, in comparison with blank MOF-808a, several new bands can be observed.…”