| Burning coals as the primary energy generates gaseous pollutants such asSO2,NOxand trace heavy metal. This paper conducted research on preparingmodified phenolic (carbon) foam as adsorbing material for SO2/NO. To improve thesurface properties and the efficiency of desulfurization and denitration, the phenolic(carbon) foams were modified by metal and organics in internal and externalmodification methods. This paper includes modifier,modification methods andvarious operation factors that affect surface characterization and SO2/NO removing.Inaddition, it was preliminarily analyzed that the mechanism and the kinetic model ofmodified phenolic foam absorbs SO2/NO.CoCl2,CeCl3,MnCl2and Zr metal coupling agent were selected as modifier. Theinternal and external modification approach were both used respectively to modifyphenolic (carbon) foams. The internally modificated metal samples were originatedfrom the precursor mixed with the metal modifier. Compared with externalmodification method, the holes in phenolic carbon foams were more evenlydistributed. Moreover, in the internal method, the modifier existed in the form ofmetal and metallic oxide; while in the external method, it dispersedly located inmaterial’s surface in the form of metal chloride.In flue gas desulfurization and denitration experiment, the results indicated thatthe efficiency of internal modification was higher than external modification. Allevidence demonstrated that the internal modification method was better thereforeshould be adopted. Among all the phenolic carbon foam samples, CFCo-nhad thehighest desulfurization (89.7%) and denitration (17.0%) efficiency. Thedesulfurization (68.7%) and denitration (8.8%) efficiency of PFCowere the highest ofphenolic foams applied in the internal modification.As organic functional groups of phenolic carbon foam disappears in the charringprocess, phenolic foam modified by organics was studied. This paper adopted urea,acrylic acid, diphenylamine and CTBN for modification. PF尿was loaded onC-N,-CONH2, which was efficient for removing SO2with the highest efficiency ofdesulfurization (62.5%). PF丙was loaded on hydroxyl group and carboxyl, which wasefficient for removing NO with the highest efficiency of denitration (7.8%). Phenolicresin foam was modified by CoCl2, urea and acrylic acid. The desulfurizationefficiency of PF3reached its maximum (72.1%) when the portfolio of CoCl2, urea andacrylic acid was5.1g,30g,15g respectively. The highest denitration efficiency(10.8%) of PF3emerged when the portfolio was5.1g,22.5g and30g respectively.Urea had the most impact on the removal of SO2and acrylic acid had the most impacton the removal of NO. Desulfurization and denitration efficiency increased along with the increase oftemperament ratio but increased at first then decreased with the increase of oxygencontent. High content of O2resulted in the competitive adsorption of SO2and NO,which reduced SO2and NO adsorption.The best amount of O2for absorption was6%.The desulfurization and denitration efficiency decreased with the increase oftemperature.Numerous experiments showed that the removing process of SO2and NO shouldcome from adsorption to catalytic oxidation. CoCl2served as a catalyst in the processof desulfurization and denitration. Chemical reactions could happen betweenoxygen-containing functional groups, nitrogen functional groups,SO2and NO. In thisexperiment, Elovich model vividly depictedthe dynamics of the phenolic foamadsorbing SO2and NO, which proved that the catalytic oxidation reaction on thesurface was actually one of the rate-controlling steps. |
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