Simultaneous Removal of SO₂ and NO from Flue Gas with Calcium-Based Sorbent at Low Temperature

Abstract

The calcium-based sorbent for simultaneous removal of SO 2 /NO was prepared with KMnO 4 as additive. The activity of sorbent was studied individually in a fixed bed at low temperature. The experimental results showed that KMnO 4 could highly enhance the sorbent ability for NO capture. It was found that temperature rise could improve SO 2 capture, but could not influence NO removal so distinctively. The presence of water vapor in the gas could prominently improve the sorbent's ability to capture SO 2 and NO, and an optimal relative humidity existed for NO removal. O 2 and KMnO 4 were found to play an important role in NO removal. The optimum condition for simultaneous SO 2 /NO removal was studied, including reaction temperature, O 2 concentration, and relative humidity in the flue gas. XRD and IC analysis indicated that SO 2 was absorbed as sulfate with KMnO 4 present and as calcium sulfite with KMnO 4 absent. It was further deduced from the experimental results that NO was first oxidized into NO 2 and then was removed by reaction with calcium hydroxide and calcium sulfite into nitrate and nitrite.

Cerium impregnated palm shell activated carbon (Ce/PSAC) sorbent for simultaneous removal of SO2 and NO—Process study

“…The sorption capacity also increased with increasing RH from 115.8 mg/g to 131.5 mg/g. A similar report was presented by [20,21] over calcium based adsorbent, with SO 2 sorption increased with the addition of water vapor into the simulated flue gas [20,21]. Moreover water accumulating on the surface and interior pore of sorbent forms a liquid film which could make the reaction gas (SO 2 ), more easily absorbed by the sorbent rather than gas-solid reaction [22].…”

“…A similar finding was reported for AC impregnated with V 2 O 5 [24], whereby in this work it was suggested that pore blockage was due to the by-products produced (ammonium-sulfate salts) during the reaction and the main reason for the unfavorable removal of NO at higher percentage of RH. Another similar finding reported a trend for NO removal with calcium based sorbent, and found the possible reason as surfacecatalyzed [20]. Therefore it can be concluded that when more water than necessary was on the sorbent surface, the water will foul the surface reaction.…”

Modeling and simulation of an improved ammonia-based desulfurization process for Claus tail gas treatment

“…It is signicantly indicated that the emission cannot meet the new standard even the Claus tail gas is treated by the mentioned additional process. On this occasion, various absorption technologies, such as CaO, [16][17][18] MgO 19-21 and NH 3 (ref. [22][23][24] based desulfurization processes, are seriously considered as the potential candidate for Claus tail gas treatment due to the higher sulfur removal efficiency (can reach almost 100%) and low cost.…”

Performance characteristics of NO removal by cobalt diethylenetriamine solution

“…This process has a leading position on the current denoxing market. The drawbacks are its relatively high costs and poisoning of the catalyst by arsenic or alkali compounds in the fly ash [3,4].…”

“…These complexes, such as ferrous and cobalt chelates, can coordinate NO and be regenerated by different methods. Long et al pointed out that NO could be removed from exhausted gas streams by [Co(en) 3 ] 2+ (en=Ethylenediamine) or [Co(NH 3 ) 6 ] 2+ solution which could realize the oxidation and absorption of nitric oxide in the same reactor [14][15][16]. This process was superior to the method using Fe(II)-EDTA (EDTA=ethylenediamine-tetraacetate) solution because these cobalt chelates are substantially more resistant to oxidation than Fe(II)-EDTA [17].…”