Metal-Modified Active Coke for Simultaneous Removal of SO2 and

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Metal-modified active coke for simultaneous removal of SO2 and NOX from sintering flue gas Yanran Zuo, Honghong Yi, and Xiaolong Tang Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/ef502103h • Publication Date (Web): 02 Dec 2014 Downloaded from http://pubs.acs.org on December 3, 2014

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Energy & Fuels

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Metal-Modified Active Coke for Simultaneous Removal of SO2 and

2

NOx from Sintering Flue Gas

3 4

Yanran Zuo, Honghong Yi,* and Xiaolong Tang

5

College of Civil and Environmental Engineering, University of Science and Technology

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Beijing, Beijing 100083, China

7

1

ACS Paragon Plus Environment

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8

ABSTRACT:

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metal-combinations (Na/Ba/Cu, Na&Cu/Na&Ba, Na&Ba&La/Na&Ba&Ce), supporting different

10

content of metal and calcined at different temperatures were investigated for simultaneous

11

removal of SO2 and NOx. The activity test results showed that supporting 8% NaCO3, 7%

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Ba(NO3)2 & 8% NaCO3 and 10% Ce(NO3)2 & 7% Ba(NO3)2 & 8% NaCO3 on the active coke

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was best respectively in unitary-, bibasic- and ternary-metal modification. And supporting

14

10%Ce(NO3)2 & 7%Ba(NO3)2 & 8%NaCO3 was the best of all. The FTIR result showed that the

15

sodium modification made some unsaturated groups and metal chelate complexes formed on the

16

active coke so that the removal performance improved. The barium added to 8%Na-AC

17

augmented the amount of unsaturated groups so as to improve the performance further. The

18

addition of cerium to 7%Ba-8%Na-AC made more unsaturated groups and metal chelate

19

complexes formed, thus raised the performance again. The BET result showed that the

20

unmodified (AC) and modified (10%Ce-7%Ba-8%Na-AC) active cokes were predominantly

21

microporous materials and the pore size distribution and pore width of the modified one was

22

more extensive and multiple, which were beneficial for the removal of SO2 and NOX. Moreover,

23

the removal performance improved significantly as the calcination temperature increased from

24

200°C to 600°C, whereas slumped as the calcination temperature increased from 600°C to 800°C.

25

It was explained by the results of XRD and BET that CeO2 which was one of the active

26

ingredients on the active coke increased with the increase of the calcination temperature and the

27

higher the sample calcined at a temperature, the worse the pore structure of the carrier was.

28

KEYWORDS：：simultaneous removal of SO2 and NOX; metal modification; rare earth element;

29

calcination temperature.

A

series

of

active

coke-based

adsorbents

2


modified

by

different

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1. INTRODUCTION

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Steel is a kind of essential material for modern society, but steel-making process is characterized

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by high energy-consumption and emission as well as heavy environmental pollution.1 The flue

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gases produced in the sintering process contain dusts, COX, SOX, and NOX, CH compounds, and

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trace amounts of dioxin and furan carcinogenic substance.2 Among these, SO2 and NOX are the

35

main air pollutions. Unlike the flue gases from coal-fired power plants, sintering flue gases have

36

the characteristics of low SO2 and NOX content, high flue gas amount, high temperature, complex

37

composition and poor stability3, 4 so that some existing desulfurization and denitration methods

38

for coal-fired flue gas are not suitable for sintering flue gas.

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Active coke (AC) is a granular carbonization product of a relatively low specific surface

40

area (150-300 m2/g) but it shows great mechanical strength, high ignition temperature, big

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granulation (gas flow resistance) and low price. The capability of removing various of complex

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pollutants makes the active coke an ideal material for purification of flue gases in industry.5 Thus,

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active coke absorber that belongs to the techniques of dry processes is a promising and suitable

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method for simultaneous removal of SO2 and NOX in sintering flue gas. Many studies have been

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examined that many metal compounds supported on carrier material have significant effect on

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removal of SO2 and NOX.6 10 So supporting metal compounds onto the active coke is a highly

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hopeful method to improve the performance of desulfurization and denitration. Nevertheless, the

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scientific comparison of different metal-combinations supporting on the active coke has been

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studied in few researches.

−

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In this work, a series of active coke-based adsorbents modified by different

51

metal-combinations, supported different content of metal and calcined at different temperatures 3


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were investigated for simultaneous removal of SO2 and NOX by means of some characterizations

53

and a simulated flue gas purification device.

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2. EXPERIMENTAL SECTION

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2.1. Preparation of Adsorbent

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Firstly, the active coke was ground into small particles, sieved to 20-40 mesh, washed five

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times with deionized water to remove dirt and fines and then dried at 110°C for 8h in a dying

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oven. Secondly, the cleaned active coke was dipped in a solution of 1M HNO3 and boiled for 1h,

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then washed with distilled water till there was no further change in pH and dried at 110°C for 12h.

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Then, the active coke was treated with metal compound(s) solution of an appropriate

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concentration by incipient wetness impregnation with ultrasonic for 60min at 30°C and then dried

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at 110°C for 12h. The metal compound(s) solution consisted of a mix of water and the metal

64

compound(s) which was(were) required to be loaded in the active coke. At last, the treated active

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coke was calcined for 4h at a specific temperature in pipe furnace in N2 atmosphere.

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2.2. Activity Test

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Activity test of SO2 and NOX removal was carried out under atmospheric pressure in the

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fixed bed reactor with a quartz tube of 10mm inner diameter at 120°C. 1g adsorbent was loaded

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into the cental of the reactor. The feed gas contained 1000ppm SO2, 600ppm NOX ( just NO),

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15%O2 and balance N2. The space velocity was 7600h-1. Concentrations of SO2, NOX (NO and

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NO2) and O2 in the inlet and outlet of the reactor were measured on-line by a Flue Gas Analyzer

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(KM9106). The minimum detection limit of Flue Gas Analyzer for SO2, NO and O2 is 1ppm and

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0.1% respectively. The flow chart of experimental system is shown in Fig. 1. 4


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2.3. Characterization

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Microstructure observation of the interface and element distribution of samples was

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characterized using a Zeiss Evo18 Scanning Electron Microscope. Fourier transform infrared

77

(FTIR) spectra were recorded on a Magna-750 Fourier transform infrared spectrometer using K

78

Br pellets. Surface area and pore size distribution for the samples were measured by a

79

QuadraSorb SI (Quantachrome instruments) surface area analyzer with the nitrogen

80

adsorption-desorption method. X-ray diffraction patterns (XRD) were recorded with a Rigaku

81

diffractometer (Ultima IV, Japan) operated at 40 kV and 40 mA by using Cu target at a rate of 20

82

(◦)/min from 2θ = 10° to 100°.

83 84

3. RESULTS AND DISCUSSION

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3.1. Unitary-Mmetal Modification

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In this part, Cu(NO3)2, Ba(NO3)2 and NaCO3 were selected to be the precursors that

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respectively supported on the active coke. The loadings of Cu(NO3)2, Ba(NO3)2 and Na2CO3 were

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7%, 7%, 8% (respectively calculated by CuO, BaO and Na2CO3).

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As shown in Fig. 2, the pure active coke could hardly remove SO2 and NOX (NO and NO2),

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especially NOX (NO and NO2), but the desulfurization and denitration performance of AC-H

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(pretreated by HNO3) improved, especially SO2. Fig. 3 showed that the pore structure of active

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coke became plentiful and complex after pretreatment. It meaned that HNO3 pretreatment

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removed impurities on the active coke and then formed more pore to adsorb SO2 and NOX. Fig. 2

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also showed that all modified active cokes were better than the unmodified one both in

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desulfurization and denitration. The sodium modified one was the best and the copper modified 5


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one was the worst. The FTIR spectra of 8%Na-AC and AC were compared to explain the better

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performance of sodium modification. As shown in Fig. 4(c, d), a broad strong peak nearly at

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3427cm-1 which could be attributed to OH combination stretching vibration of hydroxyl groups

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and physically adsorbed water11 was all noted in the two samples. It was from the active coke

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itself. In the spectra of AC, two broad and weak peaks at 1629cm-1 and 1136cm-1 were observed,

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which could be assigned to NH2 scissoring mode of aniline ring and C-N respectively.12, 13 The

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presence of NH2 scissoring mode of aniline ring and C-N might be resulted from the pretreatment

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of HNO3 on the active coke. In the spectra of 8%Na-AC, three new peaks at 1435cm-1, 1084cm-1

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and 880cm-1 which were assigned C=C14 and C=N15, NH216 and M-O17 (M means metal)

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respectively appeared after sodium modification. It meaned that sodium modification made a

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large number of unsaturated groups and metal chelate complexes formed on the active coke so

107

that the adsorption performance improved. In addition, copper supported on carrier materials was

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in favor of SO2 and NOX removal because the mediator of CuSO4 was formed during adsorption

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process.18−20 The good performance of barium modification could be due to that barium improved

110

the NOX storage and sulfur-resistance of adsorbent.21, 22

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In order to improve the adsorption ability for SO2 and NOX, the sodium content in

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adsorbents was studied. The result was exhibited in Fig. 5. It showed that the performance

113

increased at the sodium content from 4% to 8% and decreased from 8% to 12%. Too much

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supported sodium was far from better. Perhaps because more supported sodium might result in

115

the pore of active coke blocked so that SO2 and NOX couldn't enter into the pore and be stored in

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active coke.

6


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3.2. Bibasic-Metal Modification

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From the previous section, the content of the same metal increasing further did not make the

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adsorption ability rise further. But different metal compounds have different sizes and distribution

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characteristics on carriers. Maybe the addition of other metal could improve the adsorption ability.

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In this part, 7% Cu(NO3)2 and 7% Ba(NO3)2 (calculated by CuO and BaO) respectively added to

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8% NaCO3 were selected to be the precursors supported on the active coke.

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The results were presented in Fig. 6. It could be seen that the addition of copper and barium

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both had some improvement on the desulfurization and denitration, especially desulfurization.

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And barium had the advantage over copper in desulfurization and denitration, especially NO2. It

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was consistent with the previous literatures that barium had an advantage for NO2 storage of

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adsorbent because of the mediator of Ba(NO3)2.22 The FTIR spectra of 7%Ba-8%Na-AC were

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investigated to analyze the good performance of the addition of barium.In the spectra of

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7%Ba-8%Na-AC, some new peaks at 1049cm-1 and 858cm-1 which were assigned to C-O23 and

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C-C24 appeared. As shown in Fig. 4(b,c), the peaks at 3427cm-1 (OH) and 1435cm-1 (C=C and

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C=N) still existed after the addition of barium and the peak at 1435cm-1 became stronger. So the

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addition of the barium which augmented the amount of unsaturated groups might resulted in

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improvement of the performance of simultaneous SO2 and NOX removal.

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To find the optimal supported content and avoid too much barium blocking the active coke,

135

the content of added barium was studied. The results were showed in Fig. 7. The gaps of the

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performance of SO2 and NOX removal between different contents were not very obvious. But it

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could still be found that the content of 7% was the best.

7


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3.3. Addition of Rare Earth Element (Ternary-Metal Modification)

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The rare earth elements have special structures so that they have excellent physical,

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chemical, magnetic, optical, electrical properties and have been applied in many areas. So 10%

141

cerium and 10% lanthanum (calculated by Ce and La) were added to 7%Ba-8%Na-AC and

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7%Cu-8%Ba-AC respectively for further improvement of SO2 and NOX removal.

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As shown in Fig. 8, no matter which rare earth was added, barium also had the advantage

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over copper in desulfurization and denitration. It was consistent with the previous section. The

145

desulfurization

146

cerium/lanthanum into 7%Ba-8%Na-AC and 7%Cu-8%Na-AC. And the improvement of cerium

147

was greater than lanthanum. Y. Chen et al. found that the lanthanum element could raise the

148

activity of lattice oxygen, so the addition of lanthanum could improve the performance of

149

bibasic-metal modified adsorbent.25 In Fig. 4, the spectra of 10%Ce-7%Ba-8%Na-AC also

150

changed a lot. The peak at 1435cm-1 ( C=C and C=N ) became a little weaker but the peaks near

151

at 500cm-1 which could be assigned to M=O24 were more after the addition of cerium element. It

152

meaned that the addition of cerium element made more unsaturated groups and metal chelate

153

complexes formed, thus raised the performance of SO2 and NOX removal.

and

denitration

performances

were

promoted

by

the

additions

of

154

To find the optimal supported content and avoid too much cerium blocking the active coke

155

as well, the content of added cerium was studied. The results were showed in Fig. 9-2. The gaps

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of the performance of SO2 and NOX removal between different contents were not very obvious.

157

But it could still be found that the content of 10% was the best.

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Above all, 10%Ce-7%Ba-8%Na-AC was the best metal modified adsorbent for simultaneous

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removal of SO2 and NOX. So 10%Ce-7%Ba-8%Na-AC was selected to investigate the influence 8


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of metal-modification on the active coke in the aspect of pore character. The N2 adsorption

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isotherms and pore size distributions of AC and 10%Ce-7%Ba-8%Na-AC were shown in Fig.

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10(a,b) and the structural parameters calculated were displayed in Table 1. In Fig. 10A(a,b), the

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unmodified and modified active cokes both exhibited an adsorption isotherm of type I according

164

to IUPAC, i.e. The knee of the isotherm was sharp and the plateau was fairly horizontal, which

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indicated the samples were predominantly microporous materials.26, 27 The results in Fig. 10B(a,b)

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showed the most pores width of unmodified and modified active cokes were both smaller than 2.0

167

nm and there were some differences between them in the pore size distribution. There were a

168

strong and narrow peak and a weak peak respectively centering at 0.8nm and 1.3nm in the pore

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size distribution of the unmodified active coke. And there were a broad peak centering at 0.8nm

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and several weak peaks distributing 1~3nm in the pore size distribution of the modified active

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coke. So the pore size distribution of the modified sample was more extensive and its pore width

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was more multiple and complicated. According to Table 1, the micropore surface area and

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micropore pore volume of unmodified and modified active cokes both held the most proportion

174

of total surface area and pore volume. Comparing with the unmodified sample (AC), the average

175

pore width of 10%Ce-7%Ba-8%Na-AC increased and the surface area and pore volume of

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10%Ce-7%Ba-8%Na-AC decreased significantly. The above results might suggest that the

177

micropores played an important role in the physisorption and chemisorption process of SO2 and

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NOX and multiple and complicated pore were more beneficial for the simultaneous removal of

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SO2 and NOX.

9


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3.4. Effect of Calcination Temperature

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Calcination is the process of catalyst activation, grain distribution and formation. It is

182

important in the preparation of a catalyst. Calcination temperature not only influences the degree

183

of decomposition of metal salts, but also relates to the re-distribution and species of products on

184

carriers. Most supported precursors are inactive and the active sites could just form at appropriate

185

calcination temperatures. Moreover, the calcination temperature has a great influence on the

186

structure of carrier. In this part, 10%Ce-7%Ba-8%Na-AC was calcined at different temperatures.

187

The results of active test were shown in Fig. 11. It presented that the removal performance of SO2

188

and NOX improved significantly as the calcination temperature increased from 200°C to 600°C,

189

whereas slumped as the calcination temperature increased from 600°C to 800°C.

190

The crystal structures of 10%Ce-7%Ba-8%Na-AC at calcination temperatures of 200°C,

191

400°C, 600°C and 800°C were investigated by XRD analysis to better explain the influence of

192

different calcination temperatures on the removal performance of SO2 and NOX. The XRD

193

patterns of the four samples were exhibited in Fig. 12. The results revealed that the calcination

194

temperature obviously influenced the species and contents of the generated metal compounds on

195

the active coke. Due to the well dispersion and small crystals formed on the active coke surface,

196

some metal compounds were hard to be seen on the XRD pattern, but some metal species could

197

still be observed apparently. With the increase of the calcination temperature from 200°C to

198

800°C, the precursor of Ba(NO3)2 disappeared, a small number of BaCO3 and BaCeO3 appeared

199

and the generated CeO2 increased. It was detected that CeO2 was one of the active ingredients

200

which were in favor of the simultaneous removal of SO2 and NOX. However, at the rang from

201

600°C to 800°C, higher calcination temperatures could not result in better removal performance. 10


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The N2 adsorption isotherms, pore size distributions and structure parameters of samples which

203

were calcined at 600°C and 800°C were used to explain this contradiction. The results were

204

shown in Fig. 10(b,c) and Table 1. According to IUPAC, the N2 adsorption isotherms of the two

205

samples both exhibited an adsorption isotherm of type I, which indicated that the samples were

206

predominantly microporous materials. In the pore size distribution, the peaks of the sample which

207

was calcined at 800°C were narrow and shifted to the right. Its surface area and pore volume

208

decreased and average pore width increased. It meaned that the higher the sample calcined at a

209

temperature, the worse the pore structure of the carrier was. It is well-known that the bad pore

210

structure of an adsorbent can go against its adsorption. So higher calcination temperatures worsen

211

the removal performance of SO2 and NOX at the range from 600°C to 800°C.

212

From all the SO2, NO and NOX breakthrough curves of all adsorbents, it indicated some

213

same laws that SO2 exit concentration kept approximate zero for a relatively long time and then

214

increased suddenly, NO exit concentration was increasing from zero to near 600 ppm at a

215

decreasing rate and after keeping approximate zero for a relatively short time, NO2 exit

216

concentration began to increased and then plunged when SO2 exit concentration increased. Rubel,

217

A. M. et al. found that the presence of SO2 inhibited NO2 adsorption due to blocking of the

218

reaction sites involved in the conversion of NO to NO2.28 SO2 showed a greater adsorption

219

affinity than NOX, with more SO2 adsorbed as less NOX was adsorbed.29 So it could indicate that

220

SO2 was easy to be oxidized to SO3 and then chemically adsorbed. NO was mainly physically

221

adsorbed weakly and secondary conversed to NO2. NO2 could be chemically adsorbed strongly,

222

but SO2 could replace NO2 adsorbed.30 The increase of SO2 exit concentration meant that less and

223

less SO2 was adsorbed so that less and less NO2 adsorbed was replaced, namely, the plunge of 11


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224

NO2 exit concentration. There existed a competing adsorption phenomena between SO2 and NO2

225

and SO2 was more competitive than NO2 under the experimental condition in this paper.

226 227

4. CONCLUSION

228

The active cokes modified by an unitary metal (Na, Cu and Ba) all improved the performance of

229

simultaneous removal of SO2 and NOX and supporting 8% sodium was the best. It was proved by

230

FTIR that the sodium modification made some unsaturated groups and metal chelate complexes

231

formed on the active coke so that the adsorption performance improved.

232

Compared with the unitary-metal modification, the bibasic-metal modifications (Cu & Na

233

and Ba & Na) were both better and supporting 7%Ba & 8%Na was the best. It was proved by

234

FTIR that the barium added to 8%Na-AC augmented the amount of unsaturated groups (C=C and

235

C=N) so as to improve the performance.

236

In the ternary-metal modification, the additions of cerium/lanthanum to 7%Ba-8%Na-AC,

237

especially 10% cerium, raised the performance. It was proved by FTIR that the addition of cerium

238

made more unsaturated groups and metal chelate complexes (M=O) formed. Moreover, the BET

239

results of AC and 10%Ce-7%Ba-8%Na-AC showed that the micropores played an important role

240

in the physisorption and chemisorption process of SO2 and NOX. The pore size distribution of the

241

modified sample was more extensive and its pore width was more multiple and complicated,

242

which were more beneficial for the simultaneous removal of SO2 and NOX.

243

The removal performance of SO2 and NOX improved significantly as the calcination

244

temperature increased from 200°C to 600°C, whereas slumped as the calcination temperature

245

increased from 600°C to 800°C. The XRD result showed that CeO2 was one of the active 12


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ingredients which were in favor of the simultaneous removal of SO2 and NOX. The amount of

247

CeO2 on the active coke increased with the increase of the calcination temperature. The BET

248

result showed that the higher the sample calcined at a temperature, the worse the pore structure of

249

the carrier was. The two role that the calcination temperature played on adsorbents gave rise to

250

that the temperature of 600°C was the best for simultaneous removal of SO2 and NOX.

251 252

Furthermore, there existed a competing adsorption phenomena between SO2 and NO2 and SO2 was more competitive than NO2 under the experimental condition in this paper.

253 254

■ AUTHOR INFORMATION

255

Corresponding Author:

256

*E-mail: [email protected]; Tel: +86-010-62332747; Fax: +86-010-62332747

257

Notes

258

The authors declare no competing financial interest.

259 260

■ ACKNOWLEDGEMENTS

261

This work was supported by Chinese Program for New Century Excellent Talents in University

262

(NCET-12-0776)

263

(FRF-TP-13-041).

and

Fundamental

Research

Funds

for

the

Central

Universities

264 265

■ SUPPORTING INFORMATION

266

Surface area and pore size distribution for the samples were measured by a QuadraSorb SI

267

(Quantachrome instruments) surface area analyzer with the nitrogen adsorption-desorption 13


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268

method. The samples were initially outgassed at 393 K for 24 h before adsorption isotherms were

269

generated by dosing nitrogen (at 77 K) on the carbons. The density functional theory (DFT)

270

model was used to analyze the result.

271 272

■ REFERENCES

273

(1) Jiang, T.; Fan, Z. Y.; Zhang, Y. B.; Li, G. H.; Fan, X. H. The Minerals, Metals & Materials

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Society, 2nd International Symposium on High-Temperature Metallurgical Processing 2011,

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33−40.

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(2) Fan, X. H.; Yu, Z. Y.; Gan, M.; Li, W. Q.; Ji, Z. Y. Journal of Iron and Steel Research,

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Table 1 Structure parameters of samples from nitrogen adsorption at -195.8°C. Surface area (m2/g)

Samples AC (600°C)

Total a

10%Ce-7%Ba-8%Na-AC (600°C)a 10%Ce-7%Ba-8%Na-AC (800°C)a 326

430.675

Micropore 396.274

Pore volume (ml/g) Total

Micropore

Average pore width (nm)

0.2003

0.155

1.86

333.137

282.051

0.1876

0.114

2.1205

317.086

271.997

0.1681

0.108

2.25203

a

: the calcination temperature of samples.

327 328

Figure Caption

329

Fig.1 Flow chart of experimental system.

330

Fig. 2 SO2 and NOX (NO and NO2) breakthrough curves of unitary-metal modified adsorbents.

331

Fig. 3 SEM images of A and A-H.

332

Fig. 4 FTIR spectra of: (a) 10%Ce-7%Ba-8%Na-AC; (b) 7%Ba-8%Na-AC; (c) 8%Na-AC; (d)

333

AC.

334

Fig. 5 SO2 and NOX (NO and NO2) breakthrough curves of different sodium content..

335

Fig. 6 SO2 and NOX (NO and NO2) breakthrough curves of bibasic-metal modified adsorbents.

336

Fig. 7 SO2 and NOX (NO and NO2) breakthrough curves of different barium content.

337

Fig. 8 SO2 and NOX (NO and NO2) breakthrough curves of ternary-metal modified adsorbents.

338

Fig. 9 SO2 and NOX (NO and NO2) breakthrough curves of different cerium content.

339

Fig. 10 (A) Nitrogen adsorption isotherms and (B) pore size distributions for: (a) AC calcined at

340

600°C; (b) 10%Ce-7%Ba-8%Na-AC calcined at 600°C; (c) 10%Ce-7%Ba-8%Na-AC calcined at

341

800°C.

342

Fig. 11 SO2 and NOX (NO and NO2) breakthrough curves of adsorbents at different calcination

343

temperatures. 17


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344

Fig. 12 XRD pattern of samples at different calcination temperatures.

18


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Energy & Fuels

Fig.1 Flow chart of experimental system. 284x168mm (96 x 96 DPI)


Energy & Fuels

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Fig. 2 SO2 and NOX (NO and NO2) breakthrough curves of unitary-metal modified adsorbents. 142x54mm (300 x 300 DPI)


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Energy & Fuels

Fig. 3 SEM images of A and A-H. 26136x9804mm (1 x 1 DPI)


Energy & Fuels

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Fig. 4 FTIR spectra of: (a) 10%Ce-7%Ba-8%Na-AC; (b) 7%Ba-8%Na-AC; (c) 8%Na-AC; (d) AC. 69x54mm (300 x 300 DPI)


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Energy & Fuels

Fig. 5 SO2 and NOX (NO and NO2) breakthrough curves of different sodium content. 143x55mm (300 x 300 DPI)


Energy & Fuels

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Fig. 6 SO2 and NOX (NO and NO2) breakthrough curves of bibasic-metal modified adsorbents. 142x54mm (300 x 300 DPI)


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Energy & Fuels

Fig. 7 SO2 and NOX (NO and NO2) breakthrough curves of different barium content. 142x54mm (300 x 300 DPI)


Energy & Fuels

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Fig. 8 SO2 and NOX (NO and NO2) breakthrough curves of ternary-metal modified adsorbents. 142x54mm (300 x 300 DPI)


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Energy & Fuels

Fig. 9 SO2 and NOX (NO and NO2) breakthrough curves of different cerium content. 142x54mm (300 x 300 DPI)


Energy & Fuels

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Fig. 10 (A) Nitrogen adsorption isotherms and (B) pore size distributions for: (a) AC calcined at 600℃; (b) 10%Ce-7%Ba-8%Na-AC calcined at 600℃; (c) 10%Ce-7%Ba-8%Na-AC calcined at 800℃. 142x54mm (300 x 300 DPI)


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Energy & Fuels

Fig. 11 SO2 and NOX (NO and NO2) breakthrough curves of adsorbents at different calcination temperatures. 142x54mm (300 x 300 DPI)


Energy & Fuels

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Fig. 12 XRD pattern of samples at different calcination temperatures. 69x54mm (300 x 300 DPI)


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Metal-Modified Active Coke for Simultaneous Removal of SO2 and

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