Meiqing Yu1,2, Hongjian Zhu1, Sheng Tian3, Rui Wang This email address is being protected from spambots. You need JavaScript enabled to view it.1,2, Ivan V. Kozhevnikov4 

1 School of Environmental Science and Engineering, Shandong University, Qingdao 266237, China
2 Shenzhen Research Institute of Shandong University, Shenzhen 518057, China
3 Shandong Research Institute for Chemical Technology, Qingdao University of Science & Technology, Jinan 250014, China
4 Department of Chemistry, The University of Liverpool, Liverpool, L69 7ZD, UK


Received: September 10, 2021
Revised: October 26, 2021
Accepted: October 29, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.


Download Citation: ||https://doi.org/10.4209/aaqr.210238  

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Cite this article:

Yu, M., Zhu, H., Tian, S., Wang, R., Kozhevnikov, I.V. (2021). Experimental Investigation of Simultaneous Removal of SO2 and NOx Using a Heteropoly Compound. Aerosol Air Qual. Res. 21, 210238. https://doi.org/10.4209/aaqr.210238


HIGHLIGHTS

  • Heteropoly compounds can simultaneously remove NO and SO2 from flue gas.
  • Doping of element W and solution pH affected the performance of the scrubber.
  • The desulfurization performance of NaPWMo was higher than that of HPWMo.
  • High concentration of NaPWMo solution and O2 can enhance desulfurization.
 

ABSTRACT


Aiming at developing a simple, feasible method for SO2 and NOx removal, in this work, various doping amounts of heteropolyacid and heteropolyacid salts were prepared and used in wet absorption for simultaneous removal of SO2 and NO. The desulfurization and denitrification performance was evaluated by investigating dynamic SO2 and NO absorption in a simulated reactor containing a heteropoly compound (HPC) solution along with various factors influencing the reaction. The results demonstrate that this system had a high removal efficiency of SO2 and modest NO removal. The amount of Wolfram (W) doping and the pH of the solution affecting the removal performance was studied, and a stable SO2 removal efficiency higher than 95% was obtained for HPW1Mo at a pH value of 5.5. In addition, the desulfurization performance of NaPWMo with a 50% removal efficiency was higher than that of the HPWMo solution (20%) after a 60 min reaction time. A high concentration of the NaPWMo solution and the presence of O2 were beneficial to desulfurization at room temperature. In addition, the removal efficiency of SO2 or NO by NaPWMo was only affected by its own gas concentration rather than their mutual influences on each other. This work should be beneficial to the optimization leading to the development of simultaneous desulfurization and denitrification systems in practical applications.


Keywords: Polyoxometalate, SO2, NO, Absorption, Removal efficiency


1 INTRODUCTION


All over the world, a large amount of flue gases from coal-fired power plants, oil refining and gas processing, and smelting are emitted into the atmosphere every day. Massive amounts of SO2 and NO, as the main gas pollutants, not only do much harm to human health, but also are commonly recognized as the major contributor to acid rain and haze formation (Mclinden et al,. 2016; Oberschelp et al., 2019; Pi et al., 2020). At present, this phenomenon is particularly prominent in China because China is the largest coal producer and consumer in the world. On the other hand, the new emission standards adopted by governments at the global scale have put forward stricter requirements for limiting SO2 and NO emissions. Thus, SO2 and NO removal is a great concern that needs to be resolved as soon as possible. However, the development of new, efficient desulfurization and denitrification technologies is still necessary.

Commonly used SO2 removal methods for flue gas include dry absorption and wet absorption. Activated carbon, activated coke, and zeolite have been widely used in dry absorption due to several advantages, including low cost and high operational flexibility (Karatepe et al., 2008; Yan et al., 2013; Rezaei et al., 2015; Xu et al., 2016), but the low sulfur loading process still needs further improvement. Wet flue-gas desulfurization technology (WFGD) is regarded as the most industrialized process, especially the lime/limestone process, because of its high efficiency and stability (Liu et al., 2010; Yan et al., 2013). However, the main drawbacks (high costs, complex equipment, and the formation of secondary pollutants) restrict its wider applications (Chen et al., 2015; Hao et al., 2017). Several denitrification technologies, including selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR), are available for NOx removal (Zhang et al., 2016). Among them, SCR with NH3 as the reducing agent is the most widely applied method in stationary source combustion units owing to its high efficiency and selectivity (Forzatti et al., 2009; Imanaka and Masui 2012). However, the presence of H2O and SO2 in power plant flue gas and vehicle exhaust gas causes the deposition of (NH4)2SO4/NH4HSO4 and metal sulfates, in turn poisoning the catalyst (Han et al., 2019). The separate removal of SO2 and NOx results in many problems; thus, a great deal of attention has been paid to developing a system for simultaneous removal of SO2 and NOx.

Recently, the oxidation-absorption process has been shown to have great advantages in many processes for simultaneous removal of NOx and SO2. Some common oxidants, including H2O2 (Liu et al., 2011; Zhao et al., 2017), Na2S2O8 (Khan and Adewuyi, 2010; Xi et al., 2019), O3 (Li et al., 2020), and NaClO (Mondal and Chelluboyana, 2013), show better NOx removal efficiency using the wet method. Liu et al. (2019) studied the simultaneous removal of SO2 and NOx through a two-stage process composed of catalytic ozonation and the subsequent absorption of reaction gases by NH3/(NH4)2S2O8. The main products were ammonium sulfate and ammonium nitrate, which can be used as fertilizers. Activated circulating fluidized bed boiler (CFB) fly ash used as a catalyst has been applied in the simultaneous removal of NOx and SO2, which can achieve 99% SO2 and 92% NOx removal efficiency at 140°C with 2 mol L1 and 5 mol L1 of H2O2, respectively (Cui et al., 2020). Zhou et al. (2020) proposed a novel process that can achieve a higher NOx and SO2 removal efficiency and a lower nitrate concentration by using urea peroxide (CO(NH2)2·H2O2) combined with a countercurrent wet scrubber. The synergistic desulfurization and denitrification effect of the catalyst and the effect of the corona discharge on the activity of the catalyst were studied, where the desulfurization and denitrification rates on the La-Ce-V-Cu-ZSM-5 catalyst reached 97% and 83%, respectively (Qi et al., 2020). In these studies, the simultaneous removal of SO2 and NO was achieved by adding oxidants or composites. However, it is worth attempting to develop a simple, feasible method that can accomplish this goal without an oxidizing agent. The heteropoly compound (HPC) has several advantages, including versatility, favorable acidity, oxidation-reduction flexibility, and a pseudo-liquid phase feature, that have attracted significant scholarly attention and have been widely used in oil desulfurization, where it exhibits excellent activity (Zhang and Wang, 2018; Dou and Wang, 2019). In our previous work, various solid HPCs were prepared and studied initially as adsorbents used for capturing NOx (Wang et al., 2020; Zhang et al., 2020).

In this study, various doped heteropoly acids and heteropoly acid salts were prepared and used in wet absorption for simultaneous removal of SO2 and NO. The removal performance was investigated in a simulated reactor contained an HPC solution. The factors influencing the removal performance, such as the doping amount, the reaction temperature, the HPC concentration, and the NO/SO2 concentrations, were investigated. This work should be beneficial to demonstrating the optimization potential of simultaneous desulfurization and denitrification systems for practical application.

 
2 EXPERIMENTAL PROCEDURE


 
2.1 Materials

All chemicals were of analytical reagent grade and used without further purification. H3PMo12O40, H3PW12O40, H3SiW12O40 were purchased from Linghu Fine Chemical Factory. Na2WO4·2H2O, NaH2PO4·2H2O, and HCl were purchased from Sinopharm Chemical Reagent Co., Ltd., Na2MoO4·2H2O was purchased from Tianjin chemical reagent factory, China.

 
2.2 HPC Preparation

H3PW1Mo11O40, H3PW3Mo9O40, and H3PW6Mo6O40 were prepared according to the literature (Misono et al., 1982). For example, the preparation of H3PW1Mo11O40 was as follows: 26.51 g Na2MoO4·2H2O and 3.29 g Na2WO4·2H2O were dissolved in 100 mL of deionized water and heated to boil under magnetic stirring, after which 1.56 g of NaH2PO4·2H2O was added. After 30 min, a 6 mol L1 HCl solution was added dropwise to reach a pH value of 1. After 5 h, the solution was cooled to approximately 60°C, ice bathed, and transferred to a separatory funnel. Small amount of 1:1 sulfuric acid and ether were added, and the solution was shaken. The solution was divided into 3 layers after standing, and the lower layer of light green oily matter was mixed polyacid etherate. The residuary ether from the obtained mixed polyacid etherate was removed in a fume hood, and a small amount of water was added. The final product was obtained after drying at 60°C overnight. The three samples were denoted as HPW1Mo, HPW3Mo, and HPW6Mo, respectively.

The Na9[PW5Mo4O34]·2H2O was prepared as follows: 16.49 g Na2WO4·2H2O, 9.97 g Na2MoO4·2H2O and 1.56 g NaH2PO4·2H2O were dissolved in 50 mL deionized water under magnetic stirring. 12 mol L1 HCl solution was added dropwise until pH = 6. After 15 min, 25 mL acetone was added, and a light yellow oil was formed. The oil was washed with acetone several times until a powder was formed. The powder was filtered and recrystallized to obtain the product (denoted as NaPWMo).

 
2.3 Characterizations of the Catalysts

X-ray diffraction (XRD) patterns were obtained on a Bruker D8 diffractometer using Cu Kα radiation at a scan speed of 5° min−1. Fourier transform infrared (FTIR) spectroscopy was performed on a Nicolet Avatar 370, and the spectral data were recorded in a range of 400–4000 cm1 at a 4 cm1 resolution. The thermogravimetric analysis (TGA) was carried out on a TGA SDT Q 600 thermogravimetric analyzer at a heating rate of 10°C min1 ranging from 25°C to 600°C under a nitrogen atmosphere.

 
2.4 Performance Measurement

The performance evaluation system for the simultaneous removal of NO and SO2 using HPC solution is shown in Fig. 1. The system generated the simulated flue gas, and carried out the absorption of NO and SO2 and detected the outlet gas. The total flow was 500 mL min1, and the simulated gases containing SO2, NO, 4% O2 (when used) and balanced N2 were metered through mass flow controllers. The flue gas was absorbed with a 100 mL HPC solution at room temperature. The inlet and outlet SO2 and NO concentrations were continually monitored with a TH-990S SO2 and NO gas analyzer (Wuhan Tianhong, China). The SO2 and NO removal efficiencies were calculated as follows:

 

Fig. 1. Schematic diagram of simultaneous desulfurization and denitrification using the experimental device.Fig. 1. Schematic diagram of simultaneous desulfurization and denitrification using the experimental device.

 
3 RESULTS and DISCUSSION


 
3.1 XRD and FTIR

Fig. 2(a) shows the XRD pattern of HPW1Mo and NaPWMo. The diffraction peaks corresponded with the standard powder diffraction file (PDF) of H3PW12O4014H2O (PDF: 43-0317) and H3PW12O4014H2O (PDF: 50-0656) observed on HPW1Mo, confirming a synthesized heteropolyacid with a Keggin type structure. However, for NaPWMo, no regular PDF card corresponding to a single crystalline phase was observed, which may be because NaPWMo consists of several substances.

Fig. 2. XRD patterns (a) and FTIR spectra (b) of HPW1Mo and NaPWMo.
Fig. 2. XRD patterns (a) and FTIR spectra (b) of HPW1Mo and NaPWMo.

To further determine the crystal structure of the catalysts, the FTIR spectra of the as-synthesized heteropoly compound were recorded. As shown in Fig. 2(b), HPW1Mo showed obvious vibration bands at 785, 872, 965 and 1067 cm−1, corresponding to the characteristic bands of heteropolyacid with a Keggin structure as reported in the previous literature (Wu et al., 2000, 2005; Cheng and Wang, 2013). Consistent with the XRD results, the FTIR measurement confirmed that the solid Keggin heteropolyacid was successfully prepared. For NaPWMo, similar to HPW1Mo, the characteristic peaks of the Keggin heteropolyacid were also found at corresponding positions, but the peak intensity was significantly reduced.

 
3.2 TGA

Thermogravimetric analyses of HPW1Mo and NaPWMo were carried out to investigate their dehydration behavior, for which the results are shown in Fig. 3. The HPW1Mo curves in Fig. 3(a) showed three weight loss steps. Physisorbed water was evacuated below 130°C. The second weight loss step was located between 130 and 270°C, which can be regarded as structural water. Additional weight loss was observed above 300°C, which could be attributed to the decomposition of the heteropolyacids into oxides. The NaPWMo shown in Fig. 3(b) also exhibits three weight loss steps, with the second weight loss step located between 135°C and 586°C, illustrating that NaPWMo has higher thermal stability than HPW1Mo.

Fig. 3. Thermogravimetric analyses of (a) HPW1Mo and (b) NaPWMo.
Fig. 3. Thermogravimetric analyses of (a) HPW1Mo and (b) NaPWMo.

 
3.3 The Removal Performance of HPMo, HPW, and HSiW

The absorption performance of several commonly used heteropolyacids for SO2 and NO was evaluated, for which the results are shown in Fig. 4. As shown in Fig. 4(a), several heteropoly acids had similar desulfurization performance, where it can be seen that as the absorption time increased, the desulfurization performance gradually decreased. HPMo had slightly better activity, with a removal efficiency of 66% at 15 min. Its removal efficiency dropped to 21% after the reaction proceeded for 60 min. The results for NO removal are shown in Fig. 4(b). It can be observed that the three heteropolyacids had relatively stable and similar NO absorption properties, where the removal efficiency remained at approximately 15% even after 60 min of reaction.

Fig. 4. (a) Desulfurization and (b) denitrification curves for HPMo, HPW and HSiW. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M, T = 25°C.Fig. 4. (a) Desulfurization and (b) denitrification curves for HPMo, HPW and HSiW. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M, T = 25°C.

 
3.4 The Performance of HPWMo

In order to explore the effect of metal doping modifications on the performance of the absorbent, the absorption performance of HPMo doped with different amounts of W as a heteroatom was studied. As shown in Fig. 5(a), HPW1Mo exhibits significantly improved desulfurization performance, and the SO2 removal efficiency was as high as 90% at 15 min. As the number of doped W atoms increased, the SO2 removal efficiency gradually declined. The order of SO2 removal efficiency for the W-doped HPMo was as follows: HPW1Mo > HPW3Mo > HPW6Mo. The NO absorption is shown in Fig. 5(b), where it can be observed that the order of NO removal efficiency was the same as that for SO2. However, W doping had little effect on the NO removal performance of HPMo.

Fig. 5. (a) Desulfurization and (b) denitrification curves of different amounts of W doped into HPMo at a pH of 2.8. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M, T = 25°C.Fig. 5. (a) Desulfurization and (b) denitrification curves of different amounts of W doped into HPMo at a pH of 2.8. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M, T = 25°C.

 
3.5 The Effect of pH

pH is an important factor that affects absorption reactions. Therefore, the effect of pH on the absorption performance of HPWMo was studied with a comparative experiment. In this experiment, the pH of the heteropolyacid solution was adjusted to 5.5 using a NaOH solution. It can be seen in Fig. 6(a) that under a pH value of 5.5, a SO2 removal rate higher than 95% was found on HPW1Mo and remained stable for at least 60 min. HPW3Mo and HPW6Mo also showed this high removal efficiency, but their stabilization time was shorter than that of HPW1Mo, and the absorption efficiency decreased rapidly with reaction time. As the pH value of the absorption solution increased, the desulfurization efficiency also increased. This may have been due to the fact that SO2 as an acid gas is more easily absorbed by substances with a high pH value. In other words, the added alkaline solution can increase the absorption capacity of SO2. On the other hand, it may also have been because the added alkaline solution can undergo an acid-base neutralization reaction with heteropoly acid to form a sodium heteropoly salt, which leads to better absorbability of SO2. As shown in Fig. 6(b), the denitrification efficiency was not sensitive enough to the change in the pH value of the solution. A reasonable explanation for this is that due to the low solubility of NO in water, the denitrification efficiency was not as significant as the desulfurization efficiency.

Fig. 6. (a) Desulfurization and (b) denitrification curves of HPWMo at a pH value of 5.5. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M, T = 25°C.Fig. 6. (a) Desulfurization and (b) denitrification curves of HPWMo at a pH value of 5.5. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M, T = 25°C.


3.6 The Effect of Temperature

In the former experiment, it was found that using a NaOH solution to adjust the pH can improve SO2 absorbability. The absorption performance of the synthesized NaPWMo was studied in order to further explore the essential reason for this. The absorption experiments were carried out at different temperatures. From the Fig. 7(a), it can be found that temperature affected the absorption of SO2 on NaPWMo solution. When the temperature increased from 25°C to 50°C, the SO2 absorption curves displayed an obvious downward trend, implying that low temperature is beneficial to the absorption of SO2. In addition, as the absorption time was extended, the removal efficiency at each temperature decreased. NaPWMo still had higher absorption of SO2 at 25°C, and its removal efficiency was approximately 50% even after 60 min. By comparison, it can be seen that the desulfurization performance of NaPWMo was higher than that of the HPWMo solution with a 20% removal efficiency, but less than that of the HPWMo solution in which the pH was adjusted with NaOH. This indicated that the desulfurization performance of heteropolyacid salt may be better than that of parent heteropolyacid. For NO removal, as shown in Fig. 7(b), although NaPWMo had a good absorption capacity at 25°C, the greatest NO removal efficiency was only 13%, which was lower than that of HPWMo.

Fig. 7. (a) Desulfurization and (b) denitrification curves of NaPWMo at different temperatures. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M.Fig. 7. (a) Desulfurization and (b) denitrification curves of NaPWMo at different temperatures. Reaction conditions: 630 ppm SO2, 650 ppm NO, CHPC = 6 × 10–4 M.

 
3.7 The Effect of the NaPWMo Concentration

The removal efficiency of SO2 and NO can be greatly enhanced by an increase in the liquid-gas ratio. The effect of the NaPWMo concentration on SO2 and NO removal efficiency was further studied, and the results are shown in Fig. 8. It can be seen in Fig. 8(a) that at a concentration of 6 × 103 M for the NaPWMo, the SO2 removal efficiency achieved 95% within a reaction time of 60 min. When the concentration was 1.2 × 103 M, the desulfurization efficiency maintained above 90% and gradually reduced as the reaction time exceeded 45 min. Furthermore, worse desulfurization efficiency was observed with decreases in the concentration of NaPWMo. This indicated that at a higher concentration of NaPWMo, SO2 removal efficiency was improved, and the reaction time was longer. As shown in Fig. 8(b), similarly, as the concentration of NaPWMo was increased, the NO removal efficiency also increased slightly. When the concentration of NaPWMo was 6 × 103 M, the removal efficiency was as high as 16% after a reaction time of 60 min.

Fig. 8. (a) Desulfurization and (b) denitrification curves of NaPWMo at different concentrations. Reaction conditions: 630 ppm SO2, 650 ppm NO, T = 25°C.Fig. 8. (a) Desulfurization and (b) denitrification curves of NaPWMo at different concentrations. Reaction conditions: 630 ppm SO2, 650 ppm NO, T = 25°C.


3.8 The Effect of Gas Concentration

In order to better understand the ability of NaPWMo to remove SO2 and NO in complex applications, the removal performance under different gas concentrations was studied. Fig. 9(a) shows the relationship between the desulfurization efficiency and the SO2 and NO gas ratio. When the SO2 concentration in the reaction gas was maintained at 630 ppm, as the NO concentration was increased from 400 ppm to 900 ppm, the SO2 removal efficiency barely changed, indicating that the NO concentration may have little effect on the desulfurization performance of NaPWMo. When the concentration of NO remained unchanged, the absorption performance decreased significantly with increases in the concentration of SO2, which may have been because the high concentration of SO2 was absorbed more easily, causing the absorption solution to quickly reach saturation and resulting in a decrease in the removal efficiency. For NO removal, as shown in Fig. 9(b), as the NO concentration increased, the NO removal efficiency also showed a downward trend when the SO2 concentration was maintained at 630 ppm. This means that for NaPWMo, the simultaneous removal of NO and SO2 was only limited by its own gas concentration, and they did not affect each other.

Fig. 9. The effect of gas concentration on desulfurization and denitrification of NaPWMo. Reaction conditions: T = 25°C, CHPC = 1.2 × 10–4 M.Fig. 9. The effect of gas concentration on desulfurization and denitrification of NaPWMo. Reaction conditions: T = 25°C, CHPC = 1.2 × 10–4 M.


3.9 The Effect of O2

In practical applications, some oxygen may remain in flue gas because excess air has to be introduced to ensure full combustion of the fuel. An experiment was carried out to investigate the effect of O2 in the gas flow on desulfurization and denitrification of NaPWMo, for which the results are shown in Fig. 10. In Fig. 10(a), in the presence of 4% O2, SO2 removal efficiency was higher than 95% and was maintained for 45 min. However, in the absence of O2, as the reaction time increased, SO2 removal efficiency gradually decreased, and the overall removal efficiency was lower than that in the presence of O2. This implies that O2 is an important factor affecting the removal of SO2 by HPC solution. Based on previous reports (Rubio and Izquierdo, 1998; Raymundo-Piñero et al., 2000; Xu et al., 2016), when O2 is present, SO2 easily reacts with O2 to form SO3 under the action of a catalyst. SO3 and H2O further react to form H2SO4, which leads to an increase in SO2 absorption. A similar trend also can be observed in Fig. 10(b), where the NO removal efficiency clearly increased in the presence of O2. This may have been due to the fact that NO with low solubility was oxidized to NO2 and then dissolved into the HPC solution (Chen et al., 2020). According to the above experimental results, the optimal experimental conditions for simultaneous desulfurization and denitration of HPC can be summarized as follows: 400 ppm SO2, 600 ppm NO, 4% O2, T = 25°C, CHPC = 6 × 103 M.

Fig. 10. The effect of O2 on the desulfurization and denitrification of NaPWMo. Reaction conditions: 630 ppm SO2, 650 ppm NO, T = 30°C, CHPC = 2 × 10–3 M.Fig. 10. The effect of O2 on the desulfurization and denitrification of NaPWMo. Reaction conditions: 630 ppm SO2, 650 ppm NO, T = 30°C, CHPC = 2 × 10–3 M.

According to the experimental results, the reaction mechanism of simultaneous desulfurization and denitration on HPC could be deduced. First, SO2 is absorbed by water to form H2SO3, which can further be oxidized by the HPC to H2SO4. Then, the reduced HPC is used to reduce NO in the presence of O2. The reaction equation can be written as follows (taking sodium phosphomolybdate as an example):

 

In conclusion, HPC can remove SO2 and NO and at the same time act as a catalytic intermediate following Eq. (6). However, in the reaction process, due to the insufficient reaction described by Eq. (5), the HPC is consistently consumed.

It is worth paying attention to the stability of HPC when attempting simultaneous desulfurization and denitration. Repeated experiments should be conducted to verify the stability and reusable ability of HPC in future work, and the accurate reaction mechanism should further be studied.

 
4 CONCLUSION


Heteropoly compounds were employed to simultaneously remove NO and SO2 from flue gas. This system had a high SO2 removal efficiency accompanied by modest NO removal. Heteropolyacids containing P and Mo elements exhibited good removal performance. The amount of doped W and the pH of the solution affected the removal performance, where a stable SO2 removal efficiency greater than 95% was obtained on HPW1Mo at a pH value of 5.5. The desulfurization performance of NaPWMo was higher than that of the HPWMo solution. High concentration of the NaPWMo solution and the presence of O2 were beneficial to desulfurization at room temperature. The removal efficiency of the SO2 or NO in NaPWMo was only affected by its own gas concentration rather than their mutual influence on each other.

 
CONFLICTS OF INTEREST


There are no conflicts to declare.

 
ACKNOWLEDGEMENTS


This work was supported by the National Natural Science Foundation of China (No. 20206006), the Scientific Innovation program of Shenzhen city, China, under basic research program (JCYJ20170818102915033) and the Key Research and Development Program of Shandong Province, China (2017GSF217006).


REFERENCES 


  1. Chen, D., Hu, H., Xu, Z., Liu, H., Cao, J., Shen J., Yao, H. (2015). Findings of proper temperatures for arsenic capture by CaO in the simulated flue gas with and without SO2. Chem. Eng. J. 267, 201–206. https://doi.org/10.1016/j.cej.2015.01.035

  2. Chen, T., Chen, Y., Chiang, P. (2020). Enhanced performance on simultaneous removal of NOx-SO2-CO2 using a high-gravity rotating packed bed and alkaline wastes towards green process intensification. Chem. Eng. J. 393, 124678. https://doi.org/10.1016/j.cej.2020.124678

  3. Cheng, L., Wang, R. (2013). Cabbon nanotubes and nano-Ce-Zr oxides supported H3PW12O40 for effective adsorpon-decomposition of NOx. Int J. Nanosci. 11, 1240030. https://doi.org/10.1142/S0219581X12400303

  4. Cui, R., Ma, S., Yang, B., Li, S. Peng, T., Li, J., Wang, J., Sun, S., Mi, C. (2020). Simultaneous removal of NOx and SO2 with H2O2 over silica sulfuric acid catalyst synthesized from fly ash. Waste Manage. 109, 65–74. https://doi.org/10.1016/j.wasman.2020.04.049

  5. Dou, S., Wang, R. (2019). The C-Si Janus nanoparticles with supported phosphotungstic active component for Pickering emulsion desulfurization of fuel oil without stirring. Chem. Eng. J. 369, 64–76. https://doi.org/10.1016/j.cej.2019.03.050

  6. Forzatti, P., Nova, I., Tronconi, E. (2009). Enhanced NH3 selective catalytic reduction for NOx abatement. Angew. Chem. Int. Ed. 48, 8366–8368. https://doi.org/10.1002/ange.200903857

  7. Han, L., Cai, S., Gao, M., Hasegawa, J., Wang, P., Zhang, J., Shi, L., Zhang, D. (2019). Selective catalytic reduction of NOx with NH3 by using novel catalysts: State of the art and future prospects. Chem. Rev. 119, 10916–10976. https://doi.org/10.1021/acs.chemrev.9b00202

  8. Hao, R., Zhang, Y., Wang, Z., Li, Y., Yuan, B., Mao, X., Zhao, Y. (2017). An advanced wet method for simultaneous removal of SO2 and NO from coal-fired flue gas by utilizing a complex absorbent. Chem. Eng. J. 307, 562–571. https://doi.org/10.1016/j.cej.2016.08.103

  9. Imanaka, N., Masui, T. (2012). Advances in direct NOx decomposition catalysts. Appl. Catal., A 431–432, 1–8. https://doi.org/10.1016/j.apcata.2012.02.047

  10. Karatepe, N., Orbak, İ., Yavuz, R., Özyuğuran, A. (2008). Sulfur dioxide adsorption by activated carbons having different textural and chemical properties. Fuel 87, 3207–3215. https://doi.org/10.1016/j.fuel.2008.06.002

  11. Khan, N.E., Adewuyi, Y.G. (2010). Absorption and oxidation of nitric oxide (NO) by aqueous solutions of sodium persulfate in a bubble column Reactor. Ind. Eng. Chem. Res. 49, 8749–8760. https://doi.org/10.1021/ie100607u

  12. Li, B., Wu, H., Liu, X., Zhu, T., Zhao, X. (2020). Simultaneous removal of SO2 and NO using a novel method with red mud as absorbent combined with O3 oxidation. J. Hazard. Mater. 392, 122270. https://doi.org/10.1016/j.jhazmat.2020.122270

  13. Liu, B., Xu, X., Xue, Y., Liu, L., Yang, F. (2019). Simultaneous desulfurization and denitrification from flue gas by catalytic ozonation combined with NH3/(NH4)2S2O8 absorption: Mechanisms and recovery of compound fertilizer. Sci. Total Environ. 706, 136027. https://doi.org/10.1016/j.scitotenv.2019.136027

  14. Liu, Y., Bisson, T.M., Yang, H., Xu, Z. (2010). Recent developments in novel sorbents for flue gas clean up. Fuel Process. Technol. 91: 1175–1197. https://doi.org/10.1016/j.fuproc.2010.04.015

  15. Liu, Y., Zhang, J., Sheng, C. (2011). Kinetic model of NO removal from SO2-containing simulated flue gas by wet UV/H2O2 advanced oxidation process. Chem. Eng. J. 168, 183–189. https://doi.org/10.1016/j.cej.2010.12.061

  16. Mclinden, C.A., Fioletov, V., Shephard, M.W., Krotkov, N., Li, C., Martin, R.V., Moran, M.D., Joiner, J. (2016). Space-based detection of missing sulfur dioxide sources of global air pollution. Nat. Geosci. 9, 496–500. https://doi.org/10.1038/ngeo2724

  17. Misono, M., Mizuno, N., Katamura, K., Kasai, A., Konishi, Y., Sakata, K., Okuhara, T., Yoneda, Y. (1982). Catalysis by heteropoly compounds. III. The structure and properties of 12-heteropolyacids of molybdenum and tungsten (H3PMo12-xWxO40) and their salts pertinent to heterogeneous catalysis. Bull. Chem. Soci. Jpn. 55, 400–406. https://doi.org/10.1246/bcsj.55.400

  18. Mondal, M.K., Chelluboyana, V.R. (2013). New experimental results of combined SO2 and NO removal from simulated gas stream by NaClO as low-cost absorbent. Chem. Eng. J. 217, 48–53. https://doi.org/10.1016/j.cej.2012.12.002

  19. Oberschelp, C., Pfister, S., Raptis, C.E., Hellweg, S. (2019). Global emission hotspots of coal power generation. Nat. Sustainability 2, 113–121. https://doi.org/10.1038/s41893-019-0221-6

  20. Pi, X., Sun, F., Qu, Z., Gao, J., Wang, A, Zhao, G., Liu, H. (2020). Producing elemental sulfur from SO2 by calcium loaded activated coke: Enhanced activity and selectivity. Chem. Eng. J. 401, 126022. https://doi.org/10.1016/j.cej.2020.126022

  21. Qi, L., Zhao, Z., Wang, R., Gao, W., Zhang, Y. (2020). Simultaneous desulfurization and denitrification using La-Ce-V-Cu-ZS M-5 catalysts in an electrostatic precipitator. ACS Omega 5, 10525–10532. https://doi.org/10.1021/acsomega.0c00808

  22. Raymundo-Piñero, E., Cazorla-Amorós, D., Salinas-Martinez de Lecea, C., Linares-Solano, A. (2000). Factors controling the SO2 removal by porous carbons: relevance of the SO2 oxidation step. Carbon. 38, 335–344. https://doi.org/10.1016/S0008-6223(99)00109-8

  23. Rezaei, F., Rownaghi, A.A., Monjezi, S., Lively, R.P., Jones, C.W. (2015). SOx/NOx removal from flue gas streams by solid adsorbents: A review of current challenges and future directions. Energy Fuels 29, 5467–5486. https://doi.org/10.1021/acs.energyfuels.5b01286

  24. Rubio, B., Izquierdo, M.T. (1998). Low cost adsorbents for low temperature cleaning of flue gases. Fuel 77, 631–637. https://doi.org/10.1016/S0016-2361(97)00163-4

  25. Wang, R., Zhang, X., Ren, Z. (2020). Germanium-based polyoxometalates for the adsorption-decomposition of NOx. J. Hazard. Mater. 402, 123494. https://doi.org/10.1016/j.jhazmat.2020.123494

  26. Wu, Q., Meng, G. (2000). Preparation and conductibility of solid high-proton conductor molybdovanadogermanic heteropoly acid. Mater. Res. Bull. 35, 85–91. https://doi.org/10.1016/S0025-5408(00)00187-2

  27. Wu, Q., Sang, X. (2005). Synthesis and conductivity of solid high-proton conductor H5GeW10MoVO40·21H2O. Mater. Res. Bull. 40, 405–410. https://doi.org/10.1016/j.materresbull.2004.06.020

  28. Xi, H., Zhou, S., Zhou, J. (2019). New experimental results of NO removal from simulated marine engine exhaust gases by Na2S2O8/urea solutions. Chem. Eng. J. 362, 12–20. https://doi.org/10.1016/j.cej.2019.01.002

  29. Xu, X., Huang, D., Zhao, L., Kan, Y., Cao, X. (2016). Role of inherent inorganic constituents in SO2 sorption ability of biochars derived from three biomass wastes. Environ. Sci. Technol. 50, 12957–12965. https://doi.org/10.1021/acs.est.6b03077

  30. Yan, Z., Liu, L., Zhang, Y., Liang, J., Wang, J., Zhang, Z., Wang, X. (2013). Activated semi-coke in SO2 removal from flue gas: Selection of activation methodology and desulfurization mechanism study. Energy Fuel 27, 3080–3089. https://doi.org/10.1021/ef400351a

  31. Zhang, R., Liu, N., Lei, Z., Chen, B. (2016). Selective transformation of various nitrogen-containing exhaust gases toward N2 over zeolite catalysts. Chem. Rev. 116, 3658–3721. https://doi.org/10.1021/acs.chemrev.5b00474

  32. Zhang, X., Wang, R., Zhu, H., Chen, Y. (2020). Performance of NOx capture with Dawson polyoxometalate H6P2W18O6228H2O. Chem. Eng. J. 400, 125880. https://doi.org/10.1016/j.cej.2020.125880

  33. Zhang, Y., Wang, R. (2018). Synthesis of [email protected]/phosphotungstates core-shell microsphere for effective oxidative-adsorptive desulfurization of dibenzothiophene with less oxidant. Appl. Catal., B 234, 247–259. https://doi.org/10.1016/j.apcatb.2018.04.031

  34. Zhao, Y., Yuan, B, Hao, R., Tao Z. (2017). Low-temperature conversion of NO in flue gas by vaporized H2O2 and nanoscale zerovalent Iron. Energy Fuel. 37, 7282–7289. https://doi.org/10.1021/acs.energyfuels.7b00588

  35. Zhou, J., Wang, H. (2020). Study on efficient removal of SOx and NOx from marine exhaust gas by wet scrubbing method using urea peroxide solution. Chem. Eng. J. 390, 124567. https://doi.org/10.1016/j.cej.2020.124567


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