Simultaneous removal of NOx and SO2 with H2O2 catalyzed by alkali/magnetism-modified fly ash: High efficiency, Low cost and Catalytic mechanism

Yang, Bingchuan; Ma, Suxia; Cui, Rongji; Sun, Shujun; Wang, Jie; Li, Shicheng

doi:10.1016/j.cej.2018.11.068

Cited by 71 publications

(30 citation statements)

References 57 publications

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“…Yang et al. reported that NOx removal can achieve 80% efficiency when 2 M H2O2 was used as the absorbent solution at a flow rate of 0.007 mL/min in a catalytic reactor using alkali-magnetically modified fly ash catalyst, reaction temperature of 137 °C, feed gas flow rate of 300 mL/min, and NOx concentration of 350 ppm [33]. Moreover, Cui et al.…”

Section: Resultsmentioning

confidence: 99%

Nitrogen oxide reduction through absorbent solutions containing nitric acid and hydrogen peroxide in hollow fiber membrane modules

Kartohardjono

Merry

Rizky

et al. 2019

Heliyon

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Emissions of nitrogen oxides such as NO and NO2, which are commonly known as NOx, are threats to human existence and cause environmental problems. Mainly, two techniques have been developed to drastically reduce these emissions, which are dry and wet processes. The wet process has several advantages, major identifiable advantages are the adaptability to the flue gas, low operating temperatures and no poisoning and inactivation catalyst. Also, a mixture of hydrogen peroxide and nitric acid are used as absorbents solution for NOx reduction in the wet process. The advantages of using this mixture include the ability to reduce the negative effect of NOx and does not contaminate the scrubbing solution. In addition, nitric acid has an economical advantage in the process considering the fact that it is produced in the process. Finally, it can be conducted at ambient temperature. This study furthermore used a mixture of hydrogen peroxide and nitric acid solutions as an absorbent to reduce NOx in hollow fiber membrane modules. The hydrogen peroxide oxidized HNO2 to nitric acid, while enhances the oxidation through an autocatalytic reaction. The effects of the feed gas flow rate, hydrogen peroxide concentrations and number of fibers on the NOx reduction, absorbed NOx and flux were varied to study. The experimental results showed that the increase in the feed gas flow rate from 100 to 200 mL/min decreased NOx reduction from about 98 to 94% but increased the absorbed NOx and flux from about 0.13 to 0.255 mmol/h and 0.85–1.63 mmol/m2.h, respectively The increase in proportion of NOx in the feed gas effect was dominant than the increase in absorbed NOx. An increase in hydrogen peroxide concentration from 0.5 to 10 wt.% in the absorbent solutions increased NOx reduction, absorbed NOx and flux from about 94 to 98%, 0.257–0.267 mmol/h and 1.09–1.13 mmol/m2.h, respectively. Additionally, the H2O2 plays an important role in enhancing HNO2 oxidation to HNO3. Furthermore, an increase in the number of fibers from 50 to 150 in the membrane module increased NOx reduction and absorbed NOx from 86 to 97% and 0.23–0.27 mmol/h. Flux decreased from 2.98 to 1.13 mmol/m2.h due to increment in the gas-liquid contact surface area.

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Section: Resultsmentioning

confidence: 99%

Nitrogen oxide reduction through absorbent solutions containing nitric acid and hydrogen peroxide in hollow fiber membrane modules

Kartohardjono

Merry

Rizky

et al. 2019

Heliyon

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“…On the one hand, according to the two-film theory, the mass transfer rate of gas with different solubilities would decrease because of the competition effect in solution. On the other hand, according to previous studies, − the process of • OH and H 2 O 2 oxidation to remove NO and SO 2 . From eqs –reactions 2, it can be seen that excessive SO 2 can consume a lot of oxidants, such as • OH free radicals and H 2 O 2 , resulting in the reduction of soluble nitrogen oxides …”

Section: Resultsmentioning

confidence: 96%

“…In the catalytic temperature range of 100–120 °C, the removal efficiency of NO is about 18% (only H 2 O 2 ); then, the NO removal efficiency increases from 18% to about 30% when the catalytic temperature increases from 140 to 180 °C (Figure S1). This is because it is difficult for liquid phase H 2 O 2 to generate • OH without catalysts regardless of the temperature zone . The blank test indicated that the catalysts or H 2 O 2 alone could not be directly used for NO oxidation or removal because of a high activation energy barrier.…”

Section: Resultsmentioning

confidence: 99%

“…With the increasingly strict requirements for environmental protection in China, the SO 2 emission standard of coal-fired power plants has been reduced from 200 to 35 mg/m 3 . Therefore, the new technology of ultralow emission desulfurization, double-loop absorption system, is widely used in power plants. − To reduce the emission of SO 2 and NO at the same time, the double-cycle absorption system is combined with advanced oxidation processes (AOPs). − The entire removal process is divided into three parts: (1) scrubbing SO 2 by urea and generating ammonium sulfite, (2) residual NO and SO 2 can be oxidized by the vaporized H 2 O 2 /adenosine triphosphate (ATP) in the catalytic system, and (3) soluble gas pollutants and the remaining gaseous oxidants are absorbed by the ammonium sulfite that was produced from the primary-absorber.…”

Section: Introductionmentioning

confidence: 99%

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Modified Fe-Rich Palygorskite as an Efficient and Low-Cost Heterogeneous Fenton Catalyst for NO_x and SO₂ Removal

Yang

et al. 2020

Energy Fuels

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In this article, the entire removal process was based on a cycle absorption system in which a primary-absorber was used to scrub SO 2 by urea, then residual NO and SO 2 could be oxidized by the vaporized H 2 O 2 /catalysts in the catalytic system, and finally, the soluble gaseous pollutants and the remaining gaseous oxidants were absorbed by ammonium sulfite that was produced from the primary-absorber. The complex catalysts formed by iron recovery from the bauxite residue (red mud) were restructured with adenosine triphosphate (ATP) to generate mesopores with surface-active sites (FeOH) for efficient H 2 O 2 catalysis. Further, 95.2% SO 2 and 88.6% NO were removed from flue gas under the operation conditions where SO 2 concentration was 2000 ppm, NO concentration was 500 ppm, O 2 concentration was 7%, CO 2 concentration was 10%, catalytic temperature was 140 °C, H 2 O 2 feeding rate was 1.5 mL/h, and the total gas flow rate was 1.5 L/min. The results suggested that the catalytic performance is closely related to the structure of support ATP, which was elucidated by a series of experiments in different Fe loadings and BET characterization. From electron spin resonance (ESR) results, H 2 O 2 generally decompose not only into the • OH free radical by iron oxide but also into • HOO and related reactive oxygen species. According to the results of X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR), the content of FeOH and lattice oxygen in the modified ATP catalyst played an important role in the adsorption of H 2 O 2 on the protonated surface of the low-acid catalyst. Furthermore, the rational catalytic mechanism of catalyst/H 2 O 2 at low and high temperatures (corresponding to 140 and 200 °C) was proposed by transient response experiments.

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“…To ensure that the SO 2 and NO X emissions from flue gases are reduced to the barest minimum, the desulfurization and denitrification technologies in coal-fired power plants and the industrial boilers have been developed for years in compliance with the stringent emission standard [9][10][11][12][13]. However, the SO 2 emission from the non-ferrous metal smelting flue gas has received little attention in the past, hence, the control of SO 2 emission has not been optimized [14].…”

Section: Introductionmentioning

confidence: 99%

Inhibiting oxidation and enhancing absorption characteristics of sodium sulfite for SO2 removal from the non-ferrous smelting flue gas

Yuan

Zhang

et al. 2020

Environmental Engineering Research

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In this work, we investigated the absorption characteristics of SO2 and the effect of inhibitors on the desulfurization performances of Na2SO3. The results showed that the NO2 had a competitive effect with SO2 on SO32- which resulted in a significant decrease in the absorption capacity of SO2. O2 in the flue gas could decrease the absorption capacity of SO2 due to the oxidation of Na2SO3. Besides, Na2S2O3 had more excellent inhibiting effect on the oxidation of SO32-; the inhibition mechanism is understood on the basis of the free radical chain reaction, whereby S2O32- combined with the sulfite free radical to form an inert substance, thus, quenching the reaction of free radical with the dissolved oxygen and invariably inhibiting the oxidation of SO32-. Furthermore, the intrinsic and the apparent oxidation kinetics of Na2SO3 oxidation process with Na2S2O3 were investigated to explain the relationships between consumption rates of SO32- and the absorption capacities of SO2 under different components in flue gas and absorption solution.

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Simultaneous removal of NOx and SO2 with H2O2 catalyzed by alkali/magnetism-modified fly ash: High efficiency, Low cost and Catalytic mechanism

Cited by 71 publications

References 57 publications

Nitrogen oxide reduction through absorbent solutions containing nitric acid and hydrogen peroxide in hollow fiber membrane modules

Nitrogen oxide reduction through absorbent solutions containing nitric acid and hydrogen peroxide in hollow fiber membrane modules

Modified Fe-Rich Palygorskite as an Efficient and Low-Cost Heterogeneous Fenton Catalyst for NO_x and SO₂ Removal

Inhibiting oxidation and enhancing absorption characteristics of sodium sulfite for SO2 removal from the non-ferrous smelting flue gas

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Simultaneous removal of NOx and SO2 with H2O2 catalyzed by alkali/magnetism-modified fly ash: High efficiency, Low cost and Catalytic mechanism

Cited by 71 publications

References 57 publications

Nitrogen oxide reduction through absorbent solutions containing nitric acid and hydrogen peroxide in hollow fiber membrane modules

Nitrogen oxide reduction through absorbent solutions containing nitric acid and hydrogen peroxide in hollow fiber membrane modules

Modified Fe-Rich Palygorskite as an Efficient and Low-Cost Heterogeneous Fenton Catalyst for NOx and SO2 Removal

Inhibiting oxidation and enhancing absorption characteristics of sodium sulfite for SO2 removal from the non-ferrous smelting flue gas

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Modified Fe-Rich Palygorskite as an Efficient and Low-Cost Heterogeneous Fenton Catalyst for NO_x and SO₂ Removal