Catalytic Oxidation of Chlorobenzene over Mn - ACS Publications

Subscriber access provided by CORNELL UNIVERSITY LIBRARY

Article

Catalytic Oxidation of Chlorobenzene over MnxCe1-xO2/ HZSM-5 Catalysts: A Study with Practical Implications Xiaole Weng, Pengfei Sun, Yu Long, Qingjie Meng, and Zhongbiao Wu Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.6b06585 • Publication Date (Web): 14 Jun 2017 Downloaded from http://pubs.acs.org on June 17, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 28

Environmental Science & Technology

1

Catalytic Oxidation of Chlorobenzene over MnxCe1-xO2/HZSM-5

2

Catalysts: A Study with Practical Implications

3

Xiaole Weng a,b, Pengfei Suna, Yu Long a, Qingjie Menga and Zhongbiao Wu*a,b

4

a Key Laboratory of Environment Remediation and Ecological Health, Ministry of

5

Education, College of Natural Resources and Environmental Science, Zhejiang

6

University, 310058 Hangzhou, P. R. China.

7

b Zhejiang Provincial Engineering Research Centre of Industrial Boiler & Furnace

8

Flue Gas Pollution Control, 388 Yuhangtang Road, 310058 Hangzhou, P. R. China.

9 10

Corresponding author: Dr. Zhongbiao Wu, Fax/Tel: 0086-571-88982863; E-mail: [email protected].

11

Abstract

12

Industrial-use catalysts usually encounter severe deactivation after long-term

13

operation for catalytic oxidation of chlorinate volatile organic compounds (CVOCs),

14

which becomes a “bottleneck” for large-scale application of catalytic combustion

15

technology.

16

MnxCe1-xO2/HZSM-5 were investigated for the catalytic oxidation of chlorobenzene

17

(CB). The activation energy (Ea), Brønsted and Lewis acidities, CB adsorption and

18

activation behaviors, long-term stabilities, and surficial accumulation compounds

19

(after ageing) were studied using a range of analytical techniques, including XPS,

20

H2-TPR, pyridine-IR, DRIFT, and O2-TP-Ms. Experimental results revealed that the

21

Brønsted/Lewis (B/L) ratio of MnxCe1-xO2/HZSM-5 catalysts could be adjusted by ion

22

exchange of H· in HZSM-5 with Mnn+ (where the exchange with Ce4+ did not

23

distinctly affect the acidity); the long-term aged catalysts could accumulate ca. 14

24

organic compounds at surface, which included highly toxic tetrachloromethane,

25

trichloroethylene,

26

operational environment could ensure a stable performance for MnxCe1-xO2/HZSM-5

27

catalysts; this was due to the effective removal of Cl· and coke accumulations by H2O

In

this

work,

typical

tetrachloroethylene,

acidic

solid-supported

o-Dichlorobenzene,

1 / 28

ACS Paragon Plus Environment

etc.;

catalysts

high

of

humid


28

washing, and the distinct increase of Lewis acidity by the interaction of H2O with

29

HZSM-5. This work gives an in-depth view into the CB oxidation over acidic

30

solid-supported catalysts and might provide practical guidelines for the rational design

31

of reliable catalysts for industrial applications.

32 33

Key words: Chlorobenzene; Catalytic Oxidation; CeO2; MnOx; Stability; HZSM-5

34 35

TOC/Abstract Art

36 37

1. Introduction

38

Dioxins are persistent air pollutants that can cause cancer in high doses. They are

39

usually released from municipal solid waste (MSW) incineration and manufacturing

40

processes [1-3]. Catalytic combustion of dioxins and analogue compounds into

41

harmless CO2 and H2O is an efficient measure to reduce dioxin emissions [4-6].

42

In the laboratory, chlorobenzene (CB) is usually selected as an indicator to study

43

the efficiency of catalysts developed for the catalytic oxidation of dioxins [7-9]. The

44

oxidation of CB generally involves three sequential reaction processes: Cl· adsorption,

45

aromatic ring cleavage, and deep oxidation (into CO2 and H2O) [10, 11]. The

46

Cl· adsorption process is best with catalysts that have Brønsted acid sites, the

47

presence of which can induce a nucleophilic substitution between the Cl· and H· that 2 / 28


Page 2 of 28

Page 3 of 28


48

converts the CB into phenolates and facilitates the ring cleavage [12-14]. Therefore,

49

acidic solids with abundant Brønsted acid sites (e.g. HZSM-5, H-MOR, and H-BETA

50

[12, 15, and 16]) are usually selected to enhance the adsorption process. Aromatic ring

51

cleavage and deep oxidation processes are both best with the use of catalysts that have

52

high redox activities, and transition metal oxides (e.g., CeO2, CrOx, MnOx, FeOx, and

53

their bimetallic oxides [17-19]) are usually selected for this purpose.

54

In literature, catalysts consisting of acidic solids and transition metal oxides are

55

extensively studied for the catalytic oxidation of volatile organic compounds (VOCs)

56

[20], which lead to promising outcomes in terms of high activity and CO2 selectivity.

57

However, most of the reported work did not provide all insights into chlorine

58

by-products, CVOCs adsorption and activation, and Cl· and coke accumulations.

59

Particularly, identification of the long-term stabilities, deactivation mechanisms for

60

recovery and surficial accumulation compounds (after ageing) for waste disposal of

61

developed catalysts has been lacking in previous investigations. Many studies are

62

therefore insufficient to provide practical guidelines for industry, making the

63

engineering technicians unable to practically estimate the efficiencies of catalysts

64

used in industry and, as a result, many current industrial catalysts undergo severe

65

deactivation after a long-term operation.

66

In our previous study [21], we reported typical acid-solid supported catalysts,

67

MnxCe1-xO2/HZSM-5, for the catalytic oxidation of CB and assessed their activities,

68

HCl and CO2 selectivity, and CB oxidation mechanisms. In this study, we further

69

investigated the activation energy (Ea), Brønsted and Lewis acidities, CB adsorption

70

and activation behaviors, long-term stabilities (in both dry and humid conditions), Cl⋅

71

and coke accumulations and surficial accumulation compounds (after ageing) of the

72

catalysts. Our goal in this work is to give an in-depth view into the CB oxidation over

73

these acidic solid-supported catalysts and to estimate the practicality of using these

74

catalysts in industry.

3 / 28



75

2. Experimental

76

2.1 Catalyst syntheses

77

MnxCe1-xO2/HZSM-5 catalysts were synthesized via a wet impregnation route

78

where precisely measured Mn(NO3)2, Ce(NO3)3, and HZSM-5 were mixed in ethanol,

79

following by continuous stirring for 5 h. The mixture was then dried at 110 °C for 10

80

h and calcinated at 550 °C for 5 h in static air. The HZSM-5, with a Si:Al ratio of 30,

81

was supplied by Zhiyuan Molecular Co., Ltd (Shanghai, P. R. China). The resultant

82

products were denoted as MnxCe1-xO2/HZSM-5, with x values of 1, 0.8, and 0.

83

The Mn0.8Ce0.2O2 catalyst was synthesized as follows. An aqueous solution

84

containing proper amounts of Mn(NO3)2, Ce(NO3)3, and citric acid (citric

85

acid/(Mn+Ce) = 0.3 in molar ratio) was continuously stirred for 2 h at 50 °C. The

86

mixture was then dried at 110 °C for 10 h and calcinated at 550 °C for 5 h in static air.

87

The aforementioned metal salts (> 99.9%) were all supplied by SCRC (Sinopham

88

Chemical Reagent Co., Ltd, P. R. China) and used as obtained.

89

2.2 Activity measurements

90

All catalysts were sieved with 40-60 mesh and placed in a quartz fixed-bed

91

reactor. The reaction temperature was monitored using a thermocouple loaded in the

92

core of a catalyst bed with a measured temperature range of 150-400 °C. The reaction

93

feed consisted of 1000 ppm CB and 10 vol% of O2/N2 with a weight hourly space

94

velocity (WHSV) of 15,000 mL g-1 h-1. The inlet and outlet concentrations of CB were

95

analyzed online by a gas chromatograph (GC, Agilent 6890, America) equipped with

96

a flame ionization detector (FID).

97

Humidity was achieved by bubbling the N2 through water to yield a humidity of

98

approximately 10 vol% (as measured by a Hygrograph instrument, Testo 480,

99

Germany).

4 / 28


Page 4 of 28

Page 5 of 28


100

2.3 Characterizations

101

H2 temperature-programmed reduction (H2-TPR) was conducted using an

102

automatic multi-purpose adsorption instrument (TP-5079, Xianqua, Tianjin, P. R.

103

China) equipped with a custom-made thermal conductivity detector (TCD). In each

104

measurement, precisely weighted 50 mg catalyst was first pretreated in a purge of He

105

at 400 °C for 1 h and then naturally cooled to room temperature. The catalyst was

106

then subjected to a purge of 6 vol% H2/N2 at a flow rate of 30 mL min-1 and heated

107

from room temperature to 800 °C at a linear heating rate of 10 °C min-1. The

108

consumption of H2 was quantitatively measured by integrating the corresponding TPR

109

profiles and using the CuO as a standard agent for calibration.

110

X-ray photoelectron spectroscopy (XPS) was conducted using a Thermo

111

ESCALAB 250 spectrometer (U.S.A.) with an Al Kα X-ray (hν = 1486.6 eV)

112

radiation excitation source. After calibrating the binding energy scale using the signal

113

of adventurous carbon (a binding energy of 284.8 eV), the curves were fitted using a

114

Shirley background and a Gaussian peak shape with 20 % Lorentzian character.

115

Pyridine adsorbed IR spectroscopy (Py-IR) was conducted using an FT-IR

116

(Tensor 27, Bruker, Germany) equipped with a custom made IR cell that was

117

connected by a vacuum adsorption apparatus. The measurement was carried out in

118

situ and the spectra were recorded at a resolution of 4 cm-1. The catalyst was first

119

heated at a rate of 10 °C min-1 to 400 °C and then cooled to room temperature in a

120

vacuum (10-3 Pa). After that, pyridine vapor was introduced until the adsorption

121

approached saturation. The desorption process was conducted by heat-treatment of the

122

adsorbed catalyst at a linear heating rate of 10 °C min-1 to 450 °C.

123

In situ DRIFT was conducted using a Nicolet 6700 FT-IR spectrometer equipped

124

with an MCT detector. A DRIFT cell (Harrick) with CaF2 windows was fitted into a

125

heating cartridge that allowed the catalyst being heated to 400 °C in atmospheric

126

conditions. In each measurement, the catalyst was first pretreated in a flow of He

127

(99.99%, 100 mL min-1) at a temperature of 400 °C for 1 h and then naturally cooled

128

to 200 °C. Thereafter, 100 ppm CB was introduced for 15 min and then together with 5 / 28



129

a carrier gas of 10 vol% O2/N2 for another 15 min. The spectra (average of 32 scans

130

at 4 cm-1 resolution) were recorded simultaneously in each run.

131

2.4 Stability measurements

132

Surficial accumulation compounds of aged catalysts were analyzed using a

133

GC-MS instrument (Agilent 7890A GC equipped with Agilent 5975C MS, U.S.A.).

134

The catalyst was desorbed in a thermal desorption instrument (TDI, PERSEE-TP7, P.

135

R. China) where the released organic and inorganic species were simultaneously

136

analyzed using a GC-MS.

137

O2-TP-MS experiment was carried out on a custom made setup (TP-5079, Tianjin

138

Xianquan Co., Ltd., China), connected with a mass spectrometer (HIDEN QGA, UK).

139

The amount of 50 mg catalyst was first pretreated in a pure He gas flow at 200 °C for

140

1 h and then cooled to room temperature. Thereafter, catalyst was heated in a flow of

141

5% O2/He from 100 to 900 °C with a heating rate at 10 °C min-1. The signals of

142

desorbed CO2, CO, and HCl were recorded using an MS.

143

SEM-EDS mapping was carried out using an SU8010 FE-SEM operated at an

144

accelerating voltage of 3 kV with an EDS detector.

145

3. Results and Discussion

146

3.1 Apparent activation energy measurements

147

The apparent activation energy (Ea) for CB oxidation over MnxCe1-xO2/HZSM-5

148

and Mn0.8Ce0.2O2 catalysts were calculated using a first-order Arrhenius equation: r =

149

-kc = (-Aexp(-Ea/RT))c, where c, r, k, and A were the CB concentration (µmol g-1),

150

reaction rate (µmol g-1 s-1), rate constant (s-1), and pre-exponential factor, respectively

151

[22] [23].

152

Fig. 1 shows the Arrhenius plots of Mn0.8Ce0.2O2, Mn0.8Ce0.2O2/HZSM-5,

153

MnOx/HZSM-5, and CeO2/HZSM-5 catalysts with CB conversion at CeO2/HZSM-5 >

157

MnOx/HZSM-5 > Mn0.8Ce0.2O2 > Mn0.8Ce0.2O2/HZSM-5. The lowest Ea value, for

158

Mn0.8Ce0.2O2/HZSM-5, indicated that the presence of HZSM-5 and the coexistence of

159

Ce and Mn oxides both benefited the activation and oxidation of CB. To elucidate the

160

cause for such a low Ea of the Mn0.8Ce0.2O2/HZSM-5 catalyst, a series of analyses

161

were then conducted to assess the influence factors, including pore structure, redox

162

potential, oxygen mobility, and reactant absorbability, etc. [24]

163 164

Fig. 1 Arrhenius plots of ln R versus 1000/T for the Mn0.8Ce0.2O2, Mn0.8Ce0.2O2/HZSM-5,

165

MnOx/HZSM-5, CeO2/HZSM-5 catalysts and HZSM-5 in the catalytic oxidation of CB with

166

WHSV at 15000 mL g-1 h-1.

167

3.2 Catalyst characterizations

168

3.2.1 H2-TPR measurements

169

The redox potentials of MnxCe1-xO2/HZSM-5 and Mn0.8Ce0.2O2 catalysts was

170

evaluated by using H2-TPR measurements, which were conducted in the temperature

171

range of 150-600 °C. As shown in Fig. 2, the CeO2/HZSM-5 catalyst did not show

172

obvious H2 consumption peaks within the investigated temperature range. However,

173

with a magnified H2-TPR profile (see supplementary Fig. S2), a weak reduction peak 7 / 28



174

located within 400-650 °C could be observed, which originated from the reduction of

175

surficial CeO2 in the catalyst [25]. The MnOx/HZSM-5 catalyst revealed two distinct

176

H2 reduction peaks centered at approximately 365 and 453 °C. The former was

177

assigned to the reduction of Mn4+ to Mn3+ and the latter was ascribed to the reduction

178

of Mn3+ to Mn2+ [26, 27]. The extra peak at approximately 237 °C was a result of the

179

reduction of Mn3+ in tetrahedral sites, according to Stobbe et al. [28] and Weimin et al.

180

[29]. For Mn0.8Ce0.2O2 and Mn0.8Ce0.2O2/HZSM-5 catalysts, two distinct H2

181

consumption peaks were also observed. Again, the former originated from the

182

reduction of Mn4+ to Mn3+, but the latter could be an overlap peak resulting from the

183

reduction of both surficial Ce4+ to Ce3+ and Mn3+ to Mn2+ [26, 27].

184 185

Fig. 2 H2-TPR profiles of the MnxCe1-xO2/HZSM-5 and Mn0.8Ce0.2O2 catalysts.

186

From Fig. 2, it can be seen that the Mn0.8Ce0.2O2/HZSM-5 catalyst had a much

187

higher redox potential than the MnOx/HZSM-5 as a distinct low-temperature peak

188

shift was observed in the Mn0.8Ce0.2O2/HZSM-5 catalyst. The reason could be

189

ascribed to the presence of a Ce4+/Ce3+ labile cycle that enhanced the reducibility of

190

neighboring Mnn+ in MnOx [30, 31]. Moreover, the Mn0.8Ce0.2O2/HZSM-5 catalyst

191

did not show any obvious difference in redox potential as compared with that of

192

Mn0.8Ce0.2O2. Only a slight high-temperature shift was observed in the peak assigned

193

to the surficial Ce4+ to Ce3+ and Mn3+ to Mn2+ reductions (where the peak for Mn4+ to

194

Mn3+ reduction remained unchanged). This implied that the addition of HZSM-5 8 / 28


Page 8 of 28

Page 9 of 28


195

might only affect the reduction of surficial Ce4+ to Ce3+ that shifted the corresponding

196

peak to a lower temperature range.

197

The amounts of cumulative hydrogen consumption per gram by all of the

198

catalysts were calculated via integration of the corresponding TPR peaks using CuO

199

as standard agent for calibration. As shown in Table 1, the Mn0.8Ce0.2O2 catalyst

200

revealed the highest cumulative value at approximately 1.39 mol g-1. However, if

201

taking the 80 wt% HZSM-5 into account (note: the HZSM-5 could not uptake H2), the

202

Mn0.8Ce0.2O2/HZSM-5 should have a much higher cumulative H2 consumption per

203

gram of Mn0.8Ce0.2O2 than the Mn0.8Ce0.2O2 alone. This was assumed because the ion

204

exchange between the metal ions (M+) and H· (in the HZSM-5) induced a high

205

dispersion of Mn0.8Ce0.2O2 (after calcination) over the HZSM-5 support [32, 33].

206

Indeed, our SEM-EDS mapping (see supplementary Fig. S3) had revealed that the Mn

207

and Ce elemental dots in the Mn0.8Ce0.2O2/HZSM-5 catalyst were well dispersed over

208

the HZSM-5 support.

209

3.2.2 XPS measurements

210

To evaluate the surficial elemental species of MnxCe1-xO2/HZSM-5 and

211

Mn0.8Ce0.2O2 catalysts, XPS analysis was then conducted. As shown in Table 1, the

212

Mn0.8Ce0.2O2/HZSM-5 catalyst had a relatively higher Ce3+ mol% than the

213

Mn0.8Ce0.2O2. This implies that a degree of electron transfer from HZSM-5 to Ce4+

214

occurred. This electron transfer was also observed between the Mn3+ and Ce4+, which

215

led to a higher Mn4+ mol% in the Mn0.8Ce0.2O2/HZSM-5 catalyst (as compared to the

216

MnOx/HZSM-5). In O1s XPS spectra (see supplementary Fig. S4), the

217

Mn0.8Ce0.2O2/HZSM-5 catalyst showed the highest Osur mol% among all HZSM-5

218

supported catalysts. This is unsurprising given the large amounts of Ce3+ in the

219

catalyst that required abundant oxygen vacancies to compensate for charge neutrality

220

[34, 35]. As Osur is reported to be the most active oxygen species in oxidation

221

reactions [36, 37], the Mn0.8Ce0.2O2/HZSM-5 catalyst, with its high Osur mol%, was

222

unsurprising with a remarkable oxidative ability and yielded a low Ea for CB 9 / 28



Page 10 of 28

223

oxidation (see Fig. 1). The high molar ratio of Oads species (as resulting from surface

224

carbonate or hydroxyl species) observed in all HZSM-5 supported catalysts was

225

mainly due to the large amount of hydroxyl species at the HZSM-5 surface.

226

Table 1 Cumulative H2 consumption and XPS analysis of the MnxCe1-xO2/HZSM-5 and

227

Mn0.8Ce0.2O2 catalysts (The deconvolution spectra of O1s, Mn2p and Ce3d were present in

228

supplementary data).

229

Catalyst

H2 consumption ( mol/g)

MnOx/HZSM-5

Oxygen distribution (%)

Mn4+/Mn Ce3+/Ce (mol%) (mol%)

Olat

Osur

Oads

0.53

13.2

13.5

73.3

32.7

-

Mn0.8Ce0.2O2/HZSM-5

0.64

36.9

20.2

42.9

37.3

21.1

CeO2/HZSM-5

0.0065

19.5

15.4

65.2

-

13.4

Mn0.8Ce0.2O2

1.39

43.1

31.6

25.3

30.2

12.8

3.2.3 Pyridine-IR measurements

230

Ce3+ O

O O

B

e-

Mn4+

AlO

O SiO

Si-

O

H+ O

O

AlAlSiO O O O O O O SiSiSi-

Mn3+ Ce4+

231 232

Fig. 3 (A) Pyridine-IR spectra of the MnxCe1-xO2/HZSM-335, HZSM-5, and Mn0.8Ce0.2O2 10 / 28


Page 11 of 28


233

catalysts; (B) Schematic diagram describing the Mn and Ce adsorption sites on HZSM-5.

234

To evaluate the ion exchange behaviors between MnxCe1-xO2 and HZSM-5

235

catalysts, pyridine-IR measurements were conducted. In general, bands at

236

approximately 1635 and 1544 cm-1 were related to pyridine adsorbed onto Brønsted

237

sites and bands at approximately 1612 and 1455 cm-1 were related to pyridine

238

adsorbed onto Lewis sites [38-41]. The band at approximately 1490 cm-1 originated

239

from the pyridine adsorbed onto both Lewis sites and Brønsted sites [41, 42] and the

240

band at approximately 1474 cm-1 was assigned to the C-H bending of aliphatic

241

hydrocarbons bound to the oxygen atoms in a zeolite framework [43, 44]. As shown

242

in Fig. 3 and Table 2, the MnOx/HZSM-5 had a high degree of ion exchange between

243

the Mnn+ and H· in the HZSM-5, where the Brønsted/Lewis (B/L) ratio was measured

244

at approximately 0.82, much lower than that of HZSM-5 alone (at approximately

245

5.07). The reason could be ascribed to the Mn3+ ions interacting with the protons of

246

acidic bridging hydroxyl (strong Brønsted acid sites, SiAlOH), forming Mn(OH)3+

247

species that were subsequently transferred into strong Lewis acid cores after

248

calcination [33, 45]. In comparison, the CeO2/HZSM-5 had a much higher B/L ratio

249

(at approximately 3.82) than the MnOx/HZSM-5. This implies that most of the Ce4+

250

ions would interact with the non-acidic terminal silanol (SiOH) groups of the

251

HZSM-5 [46, 47], whereas only a few of the Ce4+ ions interacted with the SiAlOH

252

groups, leading to a slight decrease in the Brønsted acidity. For Mn0.8Ce0.2O2/HZSM-5

253

catalyst, the B/L ratio was approximately 0.55, much lower than those for the

254

HZSM-5 (at approximately 5.07) and Mn0.8Ce0.2O2 (at approximately 1.92), indicating

255

that a high degree of ion exchange occurred in the combined catalyst.

256

In

particular,

as

compared

with

the

MnOx/HZSM-5

catalyst,

the

257

Mn0.8Ce0.2O2/HZSM-5 catalyst showed an enhanced Lewis acidity, as the

258

characteristic bands at 1612 and 1455 cm-1 both increased. This could be a result of

259

the labile Ce3+/Ce4+ cycle that induced electron transfers from Ce4+ to Mn3+ (as

260

verified by XPS analysis, see Table 1), hence improving the electron accepting ability

261

of neighboring MnOx molecules (see Fig. 2 for the H2-TPR profile). Since the Lewis

262

acid sites were reported to be the core active sites for C-C band cleavage [14, 48], the 11 / 28



Page 12 of 28

263

Mn0.8Ce0.2O2/HZSM-5 with its high Lewis acidity was expected to yield high CO2

264

selectivity in the catalytic oxidation of CB. This assumption was consistent with

265

results presented in our previous report [21]. In sum, the pyridine-IR results suggest

266

that by tuning the molar ratio of Mn:Ce, we should be able to adjust the Brønsted and

267

Lewis acid sites of the MnxCe1-xO2/HZSM-5 catalysts for various catalytic

268

applications.

269

Table 2 Brønsted/Lewis (B/L) ratios of MnxCe1-xO2/HZSM-5, HZSM-5, and Mn0.8Ce0.2O2

270

catalysts Catalysts

Brønsted/Lewis (B/L) ratio

5.07 0.82 0.55 3.82 1.11

HZSM-5 MnOx/HZSM-5 Mn0.8Ce0.2O2/HZSM-5 CeO2/HZSM-5 Mn0.8Ce0.2O2

Mn0.8Ce0.2O2/HZSM-5

Fresh Water treated Used in dry condition Used in humid condition

0.55 0.47 1.07 0.50

271

Note: Quantitative method of B/L ratios [49]: C(pyridine on B sites= 1.88 IA(B) R2/W and

272

C(pyridine on L sites) = 1.42 IA(L) R2/W, Where C = concentration (mmol/g catalyst), IA(B, L) =

273

integrated absorbance of B or L band (cm-1), R = radius of catalyst disk (cm) , W = weight of disk

274

(mg).

275

3.2.4 DRIFT measurements

276 12 / 28


Page 13 of 28


277 278

Fig. 4 DRIFT spectra taken at 200 °C upon passing 10 vol% O2/He over the CB pre-sorbed onto

279

Mn0.8Ce0.2O2 (A) and Mn0.8Ce0.2O2/HZSM-5 (B) catalysts at different times

280

To get insights into the CB adsorption and reaction behaviors over

281

Mn0.8Ce0.2O2/HZSM-5 and Mn0.8Ce0.2O2 catalysts, in situ DRIFT measurements were

282

conducted while flowing the CB at 200 °C for 15 min followed by CB with 10% vol

283

O2 for other 15 min.

284

Fig. 4A shows the CB adsorption onto the Mn0.8Ce0.2O2 catalyst as a function of

285

time. A series of peaks were identified at approximately 1248, 1320, 1378, 1440,

286

1460, 1540, 1560, 1620, 1700, 2350, 3378, 3659, 3740 cm-1. The peaks at 1440 and

287

1540 cm-1 corresponded to the stretching vibrations of C=C in an aromatic ring [50,

288

51]. The peak at 1700 was assigned to aldehyde-type species [21, 52], and that at

289

1248 cm-1 to the C-H vibration in a plane [13, 50]. The peaks at 1320, 1378, and 1590

290

cm-1 corresponded to COOH- from bidentate formate [50] and those at 1460 and 1560

291

cm-1 corresponded to the COOH- from acetate-type species [53, 54]. The peak at 2350

292

cm-1 originated from CO2 adsorption [54, 55]. With an increase in the purging time,

293

the peaks at 1440 and 1540 cm-1 (assigned to the C=C on an aromatic ring) quickly

294

decreased. This implies that the aromatic ring in CB was cleaved once in contact with

295

the Mn0.8Ce0.2O2. The increases in the peaks at 1248 cm-1 (assigned to the vibration of

296

C-H in the plane) 1460, and 1560 cm-1 (assigned to the COOH- of acetate-type species)

297

also support this conclusion. 13 / 28



298

After O2 was introduced, the intensities of the peaks at 1700 cm-1 (assigned to

299

aldehyde-type species) 1320, 1378, and 1590 cm-1 (assigned to COOH- of bidentate

300

formates) all increased. This implies that O2 was involved in the CB oxidation

301

reaction, which dissociated the COOH- from the bidentate formates. In the hydroxyl

302

region of 3000-4000 cm-1, the peak at 3740 cm-1 originated from the produced H2O

303

[56], while peaks at 3659 and 3378 cm-1 corresponded to the consumption of hydroxyl

304

at the metal oxide surfaces [14, 57].

305

Fig. 4B shows adsorption of the CB onto the Mn0.8Ce0.2O2/HZSM-5 catalyst as a

306

function of time. As with Mn0.8Ce0.2O2, a series of peaks were identified at

307

approximately 1248, 1320, 1378, 1440, and 1460 cm-1. However, an extra peak at

308

1640 cm-1 was observed for Mn0.8Ce0.2O2/HZSM-5, which corresponded to the

309

vibration of CB adsorption onto the Brønsted sites [38, 41]. This peak quickly

310

decreased, indicating that the Brønsted sites were consistently consumed by CB

311

adsorption. As illustrated in our previous work [21], the adsorption of CB onto

312

Brønsted sites could convert the CB into phenolates via a nucleophilic substitution

313

process. These phenolates were then quickly transformed into benzoquinone or

314

cyclohexanone and facilitated the aromatic ring cleavage and deep oxidation

315

processes. Moreover, because the peaks at 1440 and 1540 cm-1 (assigned to C=C on

316

an aromatic ring) and those in the range of 1250-1500 cm-1 (corresponding to

317

oxidation products from aromatic ring cleavage) did not change as obviously as they

318

did with Mn0.8Ce0.2O2, CB oxidation over the Mn0.8Ce0.2O2/HZSM-5 barely occurred

319

at this stage. After O2 was introduced, peaks characteristic of CB oxidative products

320

appeared, indicating that the O2 had induced the cleavage of the CB aromatic rings,

321

which facilitated the deep oxidation of CB over the Mn0.8Ce0.2O2/HZSM-5 catalyst. In

322

the hydroxyl region of 3000-4000 cm-1, as with Mn0.8Ce0.2O2, peaks at approximately

323

3659 and 3378 cm-1 were also identified. However, extra peaks were observed at

324

approximately 3440 and 3290 cm-1, which could be originated from the surface

325

hydroxyl (in HZSM-5) interacting with the CB molecules that led to the formation of

326

weakened hydrogen-bonded OH- [12, 58].

327

Combined with our previous publication [21], it can be concluded that the 14 / 28


Page 14 of 28

Page 15 of 28


328

HZSM-5 was not only able to convert the CB into phenolates via the adsorption of

329

CB onto the Brønsted sites; this had facilitated the deep oxidation of CB; but also able

330

to adjust the Brønsted/Lewis (B/L) ratio via the ion exchange between Mnn+ and H·;

331

this had promoted the redox potential of Mn1-xCexO2, both of which led to a low Ea in

332

the catalytic oxidation of CB over the Mn0.8Ce0.2O2/HZSM-5 catalyst (see Fig. 1).

333

3.3 Stability measurements

334

As mentioned above, the stability of industrial catalysts in the catalytic oxidation

335

of CVOCs is still a technological problem in industry [59, 60, 61]. To assess the

336

practicality of the Mn0.8Ce0.2O2/HZSM-5 catalyst, a long-term ageing test was

337

conducted at T90 (i.e., 90% CB conversion) with a WHSV at 15,000 mL g-1h-1, in both

338

dry and humid conditions.

339

In dry conditions (see Fig. 5A), the Mn0.8Ce0.2O2/HZSM-5 and Mn0.8Ce0.2O2

340

catalysts both showed a stable performance in the first 10 h. However, their activities

341

began to drop as the experimental time approached 15 h. The Mn0.8Ce0.2O2/HZSM-5

342

catalyst retained approximately 60% CB conversion after 50 h of ageing, whereas the

343

Mn0.8Ce0.2O2 retained only approximately 25% CB conversion.

344

As indicated in our previous study [21], the activity of Mn0.8Ce0.2O2 is mainly

345

dependent on the redox potential of metal oxides where CB is dechlorinated to

346

benzene, which could then be oxidized by chemisorbed oxygen species to CO2 and

347

H2O [61]. Accordingly, deactivation of the Mn0.8Ce0.2O2 catalyst should be caused by

348

the accumulation of chloride species or coke at the metal oxide surfaces, which

349

inhibited their redox activities [61, 62]. For the Mn0.8Ce0.2O2/HZSM-5 catalyst,

350

oxidation of the CB was initiated by the adsorption of CB onto the Brønsted acid sites,

351

where they formed phenolates followed by benzoquinone or cyclohexanone species

352

[13, 14]. As such, the chloride species or coke might be in part trapped by the

353

HZSM-5 [60, 63], which to some extent protected the Mn0.8Ce0.2O2 active sites, and

354

yielded better stability than the Mn0.8Ce0.2O2 catalyst alone.

355

In a humid ageing condition (see Fig. 5B), the Mn0.8Ce0.2O2/HZSM-5 catalyst 15 / 28



356

had very stable performance within the 50 h experiment, whereas the Mn0.8Ce0.2O2

357

yielded even worse stability than in the dry ageing condition. The activity of the

358

catalyst quickly dropped after 10 h, and only approximately 10% CB conversion was

359

retained after 50 h of ageing. It was widely believed that the addition of

360

low-concentration H2O would induce a competitive adsorption with CB, hence

361

inhibiting catalytic activities [64, 65], whilst large amounts of H2O addition could

362

inhibit coke formation and promote Cl· removal from the catalyst surface [20, 66, 67].

363

To

364

Mn0.8Ce0.2O2/HZSM-5 and Mn0.8Ce0.2O2 catalysts, XPS, EDS-Mapping and

365

O2-TP-MS were then conducted.

assess the actual effects of H2O on the

stability performance of

366

367 368

Fig. 5 Stability measurements of the Mn0.8Ce0.2O2 and Mn0.8Ce0.2O2/HZSM-5 catalysts at their

369

respective T90 in (A) dry and (B) humid (RH = approximately 10 vol%) conditions.

370

371

3.3.1 XPS and pyridine-IR analyses The XPS analyses (see supplementary Fig. S5) indicated that dry-aged 16 / 28


Page 16 of 28

Page 17 of 28


372

Mn0.8Ce0.2O2 did not show obvious changes in the O1s, Mn2p, and Ce3d spectra.

373

Only distinct Cl2p characteristic peaks were observed, indicating that the long-term

374

ageing had indeed caused Cl· accumulation at the surface. For humid ageing, the XPS

375

revealed a lack of Mn2p and Ce3d characteristic peaks. Only the Oads characteristic

376

peak originated from the introduced H2O was observed, indicating that the humid

377

ageing had led to formation of a H2O layer over the catalyst surface. The aged

378

Mn0.8Ce0.2O2 therefore suffered a more severe deactivation because the presence of a

379

H2O layer inhibited the adsorption of CB and O2 for reaction.

380

For Mn0.8Ce0.2O2/HZSM-5 catalyst, the XPS did not show obvious changes in

381

O1s, Mn2p, and Ce3d spectra (in either dry or humid ageing conditions). However, a

382

slight decrease in Olat and increase in Ce3+, together with the appearance of Cl2p

383

characteristic peaks were observed in the aged sample. After pyridine-IR analysis (see

384

Fig. 6 and Table 2), it was noted that the amounts of Brønsted acidity did not change

385

distinctly after dry and humid ageing. However, the Lewis acidities decreased

386

remarkably in dry ageing, but significantly increased in humid ageing. The former

387

could be ascribed to an accumulation of Cl· over the metal oxides that suppressed

388

their electron accepting abilities, while the latter was assumed to be caused by the

389

effective removal of Cl· by H2O washing [66, 67]. Indeed, EDS-mapping (see Fig. 7)

390

indicated that the dry-aged sample had similar distributions of Cl and Mn elements,

391

implying that the Cl· species mainly accumulated on the Mn0.8Ce0.2O2 sites. In

392

comparison, for the humid-aged sample, much less Cl· and C species were observed.

393

One might argue that the increased Lewis acidity might be also caused by H2O

394

interacting with the HZSM-5 catalyst. As Marie-Rose et al. [68] reported, H2O

395

adsorption onto protonic zeolite (HZSM-5 herein) would induce a proton transfer to

396

form H2O dimers, which bonded to the anionic zeolite framework to form H5O2+ ions,

397

leading to an increase in Lewis acidity. Indeed, after H2O treatment in which the fresh

398

Mn0.8Ce0.2O2/HZSM-5 was aged in humid condition for 50 h without the addition of

399

CB, the treated catalyst also yielded enhanced Lewis acidity (see Fig. 6). This result

400

suggests that an increase in the Lewis acidity of humid-aged Mn0.8Ce0.2O2/HZSM-5

401

catalyst was caused by both H2O washing and H5O2+ formation. Since the Lewis acid 17 / 28



Page 18 of 28

402

sites have been reported to be the core active sites for C-C cleavage [14, 48], their

403

enhancement would reduce the accumulations of Cl· and coke on the catalyst surface,

404

hence enabling stable CB oxidation. This is all consistent with the stability

405

measurement results (see Fig. 5).

406

407 408

Fig. 6 Pyridine-IR spectra of the Mn0.8Ce0.2O2/HZSM-5 catalyst treated in dry or humid conditions

409 410

Fig. 7 EDS-mapping of Mn0.8Ce0.2O2/HZSM-5 catalysts aged in dry or humid conditions.

411

Considering that real-time application generally requires a pre-spraying process

412

to

remove

acidic

gases

(i.e.,

H2S)

and

water

413

dimethylformamide–DMF), an adjustment in humidity to assist the subsequent CVOC

414

oxidation process could be easily achieved. As such, the finding that a high-humidity

415

operating environment could enable stable performance for acidic solid-supported 18 / 28


soluble

species

(i.e.,

Page 19 of 28


416

catalysts might provide a solution to resolve the deactivation problem in industrial

417

applications. However, the increase in HCl corrosion and a possible collapse of the

418

monolithic catalyst structure are still of concern.

419

3.3.2 Surficial accumulation compounds analyses

420

In industry, analysis of surficial accumulation compounds for used catalysts is

421

crucial for responsible waste disposal. To evaluate the surficial accumulation

422

compounds of aged catalysts, they were all subjected to thermal desorption treatments

423

where the desorbed gaseous compounds were simultaneously analyzed using an

424

GC-MS. Fig. 8A shows the main surficial accumulation compounds for aged

425

Mn0.8Ce0.2O2 catalysts. It was noted that the compounds desorbed from the dry-aged

426

sample were mainly benzene (label 4’) and CB (label 6’) (see Table 3), while for the

427

humid-aged sample, a distinct H2O peak (label 3’) was observed, implying that the

428

surface of the catalyst was covered by significant amounts of H2O. This was

429

consistent with the XPS results (see supplementary Fig. S5).

430

Fig. 8B shows the main surficial accumulation compounds for aged

431

Mn0.8Ce0.2O2/HZSM-5. There were approximately 14 organic compounds detected

432

(see Table 3). The dry-aged sample accumulated significant organic species,

433

including non-chlorinated (e.g. labels 1, 2, 3, 5, and 10) and chlorinated ones (e.g.,

434

labels 6, 7, 8, 9, 12, 13, and 14), while the humid-aged sample had significantly

435

decreased amounts of trichloromethane (label 6), tetrachloromethane (label 7),

436

trichloroethylene (label 8), tetrachloroethylene (label 9), o-Dichlorobenzene (label 12)

437

and p-Dichlorobenzene (label 14), some of which were even undetectable. This

438

indicates that the addition of H2O indeed inhibited Cl· accumulation via an increase in

439

the Lewis acidity and removed Cl· from the catalyst via washing. It should be noted

440

that although the presence of HZSM-5 has significantly promoted the catalytic

441

performance for CB oxidation, the increase in high toxic poly-chlorinated by-products

442

(e.g. label 7, 9, 12, etc.) is still a big concern, particularly for waste disposal of used

443

catalysts in industry. 19 / 28



Page 20 of 28

444

445 446

Fig. 8 GC-MS analysis for surficial accumulation compounds on (A) Mn0.8Ce0.2O2 and (B)

447

Mn0.8Ce0.2O2/HZSM-5 aged in dry or humid conditions

448

Table 3 Ingredients of surficial accumulation compounds on aged Mn0.8Ce0.2O2/HZSM-5 and

449

Mn0.8Ce0.2O2 Mn0.8Ce0.2O2 Label

Compound name

1’ 2’ 3’

Propylene Butylene Water

4’

Benzene

5’

Acetaldehyde

6’

Chlorobenzene

7’

p-Dichlorobenzene

Mn0.8Ce0.2O2/HZSM-5 Structure

Label

Compound name

H2O

1 2 3

Propylene Butane Butylene

4

Water

5

Pentene

6

Trichloromethane

CHCl3

7

tetrachloromethan e

CHCl4

o Cl Cl

Cl 20 / 28


Structure

H2O

Page 21 of 28


8

Trichloroethylene

9

Tetrachloroethyle ne

10

Benzene

11

Chlorobenzene

12

o-Dichlorobenzen e

13

m-Dichlorobenzen e

14

p-Dichlorobenzen e

H

Cl

Cl

Cl

Cl

Cl

Cl

Cl

Cl Cl Cl Cl Cl

Cl

Cl

450

Evaluation on coke deposition of the aged catalyst was conducted using an

451

O2-TPD-MS. As shown in Fig. 9, the dry-aged sample had yielded much higher CO2

452

and CO desorption peaks than those for the humid-aged sample. This is unsurprising

453

given that humid aging induces a distinct increase in Lewis acidity, which promoted

454

the C-C band cleavage and deep oxidation processes.

455 456

Fig. 9 O2-TP-MS analysis of the Mn0.8Ce0.2O2/HZSM-5 catalysts aged in dry or humid conditions

21 / 28



457

Supporting Information

458 459 460

Arrhenius plots to eliminate the external and internal diffusion effects, XPS of deconvolution spectra, H2-TPR for CeO2, etc. are present in supplemental section. This material is available free of charge via the Internet at http://pubs.acs.org.

461

Acknowledgements

462

This work was financially supported by the National Natural Science Foundation of

463

China (Grant No. 51478418) and the Program for Zhejiang Leading Team of S&T

464

Innovation (Grant No. 2013TD07).

465

References

466

[1] R. Weber, T. Sakurai, H. Hagenmaier, Low temperature decomposition of PCDD/PCDF,

467

chlorobenzenes and PAHs by TiO2-based V2O5-WO3 catalysts, Appl. Catal. B, 20 (1999)

468

249-256.

469

[2] C. He, Y. Yu, Q. Shen, J. Chen, N. Qiao, Catalytic behavior and synergistic effect of

470

nanostructured mesoporous CuO-MnOx-CeO2 catalysts for chlorobenzene destruction,

471

Appl.Surf.Sci., 297 (2014) 59-69.

472

[3] C. He, Y. Yu, J. Shi, Q. Shen, J. Chen, H. Liu, Mesostructured Cu-Mn-Ce-O composites with

473

homogeneous bulk composition for chlorobenzene removal: Catalytic performance and

474

microactivation course, Macromol. Chem. Phys., 157 (2015) 87-100.

475

[4] H. Li, G. Lu, Q. Dai, Y. Wang, Y. Guo, Y. Guo, Efficient low-temperature catalytic combustion

476

of trichloroethylene over flower-like mesoporous Mn-doped CeO2 microspheres, Appl. Catal.

477

B, 102 (2011) 475-483.

478 479

[5] M. Guillemot, J. Mijoin, S. Mignard, P. Magnoux, Mode of zeolite catalysts deactivation during chlorinated VOCs oxidation, Appl.Catal.A, 327 (2007) 211-217.

480

[6] X. Ma, X. Feng, J. Guo, H. Cao, X. Suo, H. Sun, M. Zheng, Catalytic oxidation of 1,

481

2-dichlorobenzene over Ca-doped FeOx hollow microspheres, Appl. Catal. B, 147 (2014)

482

666-676.

483

[7] V. De Jong, M.K. Cieplik, R. Louw, Formation of dioxins in the catalytic combustion of 22 / 28


Page 22 of 28

Page 23 of 28


484

chlorobenzene and a micropollutant-like mixture on Pt/γ-AL2O3, Environ.Sci.Tec., 38 (2004)

485

5217-5223.

486 487

[8] Y. Liu, M. Luo, Z. Wei, Q. Xin, P. Ying, C. Li, Catalytic oxidation of chlorobenzene on supported manganese oxide catalysts, Appl. Catal. B, 29 (2001) 61-67.

488

[9] Q. Dai, S. Bai, J. Wang, M. Li, X. Wang, G. Lu, The effect of TiO2 doping on catalytic

489

performances of Ru/CeO2 catalysts during catalytic combustion of chlorobenzene, Appl.

490

Catal. B, 142 (2013) 222-233.

491

[10] W. Cen, Y. Liu, Z. Wu, J. Liu, H. Wang, X. Weng, Cl Species Transformation on CeO2 (111)

492

Surface and Its Effects on CVOCs Catalytic Abatement: A First-Principles Investigation, J.

493

Phys. Chem. C , 118 (2014) 6758-6766.

494

[11] J. Wang, X. Wang, X. Liu, J. Zeng, Y. Guo, T. Zhu, Kinetics and mechanism study on

495

catalytic oxidation of chlorobenzene over V2O5/TiO2 catalysts, J. Mol. Catal. A-Chem., 402

496

(2015) 1-9.

497

[12] B.H. Aristizábal, C.M. de Correa, A.I. Serykh, C.E. Hetrick, M.D. Amiridis, In situ FT-IR

498

study of the adsorption and reaction of ortho-dichlorobenzene over Pd-promoted Co-HMOR,

499

Microporous Mesoporous Mater, 112 (2008) 432-440.

500 501

[13] J. Lichtenberger, M.D. Amiridis, Catalytic oxidation of chlorinated benzenes over V2O5/TiO2 catalysts, J.Catal., 223 (2004) 296-308.

502

[14] J. Wang, X. Wang, X. Liu, T. Zhu, Y. Guo, H. Qi, Catalytic oxidation of chlorinated benzenes

503

over V2O5/TiO2 catalysts: The effects of chlorine substituents, Catal. Today, 241 (2015)

504

92-99.

505 506 507 508

[15] S. Scirè, S. Minicò, C. Crisafulli, Pt catalysts supported on H-type zeolites for the catalytic combustion of chlorobenzene, Appl. Catal. B, 45 (2003) 117-125. [16] M. Taralunga, J. Mijoin, P. Magnoux, Catalytic destruction of 1, 2-dichlorobenzene over zeolites, Catal. Commun., 7 (2006) 115-121.

509

[17] Q. Dai, H. Huang, Y. Zhu, W. Deng, S. Bai, X. Wang, G. Lu, Catalysis oxidation of 1,

510

2-dichloroethane and ethyl acetate over ceria nanocrystals with well-defined crystal planes,

511

Appl. Catal. B, 117 (2012) 360-368.

512 513

[18] X. Wang, Q. Kang, D. Li, Low-temperature catalytic combustion of chlorobenzene over MnOx-CeO2 mixed oxide catalysts, Catal. Commun, 9 (2008) 2158-2162. 23 / 28



514

[19] J. Su, Y. Liu, W. Yao, Z. Wu, Catalytic Combustion of Dichloromethane over

515

HZSM-5-Supported Typical Transition Metal (Cr, Fe, and Cu) Oxide Catalysts: A Stability

516

Study, J. Phys. Chem. C , 120 (2016) 18046-18054.

517

[20] aQ. Dai, X. Wang, G. Lu, Low-temperature catalytic destruction of chlorinated VOCs over

518

cerium oxide, Catal. Commun., 8 (2007) 1645-1649; bS. Chatterjee, H.L. Greene, Y.J. Park,

519

Comparison of modified transition metal-exchanged zeolite catalysts for oxidation of

520

chlorinated hydrocarbons, J. Catal., 138 (1992) 179-194; cH. Greene, D. Prakash, K. Athota,

521

G. Atwood, C. Vogel, Energy efficient dual-function sorbent/catalyst media for chlorinated

522

VOC destruction, Catal. Today, 27 (1996) 289-296;

523

Adsorption and catalytic destruction of trichloroethylene in hydrophobic zeolites, Appl. Catal.

524

B, 14 (1997) 37-47.

d

P.S. Chintawar, H.L. Greene,

525

[21] P. Sun, X. Dai, W. Wang, X. Weng, Z. Wu, Mechanism Study on Catalytic Oxidation of

526

Chlorobenzene over MnxCe1-xO2/H-ZSM5 Catalysts under Dry and Humid Conditions, Appl.

527

Catal. B, (2016) 389-397.

528 529 530 531

[22] M. Alifanti, M. Florea, S. Somacescu, V. Parvulescu, Supported perovskites for total oxidation of toluene, Appl. Catal. B, 60 (2005) 33-39. [23] H. Huang, Q. Dai, X. Wang, Morphology effect of Ru/CeO2 catalysts for the catalytic combustion of chlorobenzene, Appl. Catal. B, 158-159 (2014) 96-105.

532

[24] Y. Liu, H. Dai, J. Deng, Y. Du, X. Li, Z. Zhao, Y. Wang, B. Gao, H. Yang, G. Guo, In situ

533

poly (methyl methacrylate)-templating generation and excellent catalytic performance of

534

MnOx/3DOM LaMnO3 for the combustion of toluene and methanol, Appl. Catal. B, 140

535

(2013) 493-505.

536 537 538 539 540 541 542 543

[25] M.M. Natile, G. Boccaletti, A. Glisenti, Properties and reactivity of nanostructured CeO2 powders: Comparison among two synthesis procedures, Chem. Mat., 17 (2005) 6272-6286. [26] F. Arena, T. Torre, C. Raimondo, A. Parmaliana, Structure and redox properties of bulk and supported manganese oxide catalysts, Phys. Chem. Chem. Phys, 3 (2001) 1911-1917. [27] J. Carnö, M. Ferrandon, E. Björnbom, S. Järås, Mixed manganese oxide/platinum catalysts for total oxidation of model gas from wood boilers, Appl.Catal.A, 155 (1997) 265-281. [28] E. Stobbe, B. De Boer, J. Geus, The reduction and oxidation behaviour of manganese oxides, Catal. Today, 47 (1999) 161-167. 24 / 28


Page 24 of 28

Page 25 of 28


544 545

[29] W. Weimin, Y. Yongnian, Z. Jiayu, Selective reduction of nitrobenzene to nitrosobenzene over different kinds of trimanganese tetroxide catalysts, Appl.Catal.A, 133 (1995) 81-93.

546

[30] G. Liu, R. Yue, Y. Jia, Y. Ni, J. Yang, H. Liu, Z. Wang, X. Wu, Y. Chen, Catalytic oxidation of

547

benzene over Ce-Mn oxides synthesized by flame spray pyrolysis, Particuology, 11 (2013)

548

454-459.

549 550

[31] S.T. Hussain, A. Sayari, F.ç. Larachi, Enhancing the stability of Mn-Ce-O WETOX catalysts using potassium, Appl. Catal. B, 34 (2001) 1-9.

551

[32] N. Hadi, A. Niaei, S. Nabavi, M.N. Shirazi, R. Alizadeh, Effect of second metal on the

552

selectivity of Mn/H-ZSM-5 catalyst in methanol to propylene process, J. Ind. and Eng. Chem,

553

29 (2015) 52-62.

554

[33] D. Mao, W. Yang, J. Xia, B. Zhang, Q. Song, Q. Chen, Highly effective hybrid catalyst for

555

the direct synthesis of dimethyl ether from syngas with magnesium oxide-modified HZSM-5

556

as a dehydration component, J.Catal., 230 (2005) 140-149.

557 558

[34] R. Peng, X. Sun, S. Li, L. Chen, M. Fu, J. Wu, D. Ye, Shape effect of Pt/CeO2 catalysts on the catalytic oxidation of toluene, Chem. Eng. J., 306 (2016) 1234-1246.

559

[35] S. Xie, Y. Liu, J. Deng, X. Zhao, J. Yang, K. Zhang, Z. Han, H. Dai, Three-dimensionally

560

ordered macroporous CeO2-supported Pd@ Co nanoparticles: Highly active catalysts for

561

methane oxidation, J. Catal., 342 (2016) 17-26.

562 563

[36] H. Huang, Q. Dai, X. Wang, Morphology effect of Ru/CeO2 catalysts for the catalytic combustion of chlorobenzene, Appl. Catal. B, 158 (2014) 96-105.

564

[37] F. Arena, G. Trunfio, J. Negro, B. Fazio, L. Spadaro, Basic evidence of the molecular

565

dispersion of MnCeO x catalysts synthesized via a novel “redox-precipitation” route, Chem.

566

Mat, 19 (2007) 2269-2276.

567 568

[38] C. Emeis, Determination of integrated molar extinction coefficients for infrared absorption bands of pyridine adsorbed on solid acid catalysts, J.Catal., 141 (1993) 347-354.

569

[39] M.A. Makarova, K. Karim, J. Dwyer, Limitation in the application of pyridine for

570

quantitative studies of brönsted acidity in relatively aluminous zeolites, Microporou. Mater, 4

571

(1995) 243-246.

572 573

[40] E. Parry, An infrared study of pyridine adsorbed on acidic solids. Characterization of surface acidity, J.Catal., 2 (1963) 371-379. 25 / 28



574 575 576 577 578 579 580 581

[41] T. Yashima, N. Hara, Infrared study of cation-exchanged mordenites and Y faujasites adsorbed with ammonia and pyridine, J.Catal., 27 (1972) 329-333. [42] T. Barzetti, E. Selli, D. Moscotti, L. Forni, Pyridine and ammonia as probes for FT-IR analysis of solid acid catalysts, J. Chem. Soc., Faraday Trans, 92 (1996) 1401-1407. [43] J. Weitkamp, New directions in zeolite catalysis, Studies in Surface Science and Catalysis, 65 (1991) 21-46. [44] W. Farneth, R. Gorte, Methods for characterizing zeolite acidity, Chem. Rev., 95 (1995) 615-635.

582

[45] H.D. Setiabudi, A.A. Jalil, S. Triwahyono, N.H.N. Kamarudin, R.R. Mukti, IR study of

583

iridium bonded to perturbed silanol groups of Pt-HZSM5 for n-pentane isomerization,

584

Appl.Catal.A, 417 (2012) 190-199.

585

[46] J. Bi, M. Liu, C. Song, X. Wang, X. Guo, C2-C4 light olefins from bioethanol catalyzed by

586

Ce-modified nanocrystalline HZSM-5 zeolite catalysts, Appl. Catal. B, 107 (2011) 68-76.

587

[47] B. de Rivas, C. Sampedro, E. Ramos-Fernández, R. López-Fonseca, J. Gascon, M. Makkee, J.

588

Gutiérrez-Ortiz, Influence of the synthesis route on the catalytic oxidation of 1,

589

2-dichloroethane over CeO2/H-ZSM5 catalysts, Appl.Catal.A, 456 (2013) 96-104.

590

[48] B. de Rivas, R. López-Fonseca, J.R. González-Velasco, J.I. Gutiérrez-Ortiz, On the

591

mechanism of the catalytic destruction of 1, 2-dichloroethane over Ce/Zr mixed oxide

592

catalysts, J. Mol. Catal. A-Chem., 278 (2007) 181-188.

593

[49] C.A.Emeis, Determination of Integrated Molar Extinction Coefficients for Infrared

594

Absorption Bands of Pyridine Adsorbed on Solid Acid Catalysts, J.Catal.,141, no. 2 (1993)

595

347-354.

596

[50] X. Ma, Q. Sun, X. Feng, X. He, J. Guo, H. Sun, H. Cao, Catalytic oxidation of 1,

597

2-dichlorobenzene over CaCO3/α-Fe2O3 nanocomposite catalysts, Appl.Catal.A, 450 (2013)

598

143-151.

599

[51] M.A. Larrubia, G. Busca, An FT-IR study of the conversion of 2-chloropropane,

600

o-dichlorobenzene and dibenzofuran on V2O5-MoO3-TiO2 SCR-DeNOx catalysts, Appl. Catal.

601

B, 39 (2002) 343-352.

602 603

[52] M. Nagao, Y. Suda, Adsorption of benzene, toluene, and chlorobenzene on titanium dioxide, Langmuir, 5 (1989) 42-47. 26 / 28


Page 26 of 28

Page 27 of 28


604

[53] S. Lomnicki, J. Lichtenberger, Z. Xu, M. Waters, J. Kosman, M.D. Amiridis, Catalytic

605

oxidation of 2, 4, 6-trichlorophenol over vanadia/titania-based catalysts, Appl. Catal. B, 46

606

(2003) 105-119.

607 608

[54] X. Ma, X. Suo, H. Cao, J. Guo, L. Lv, H. Sun, M. Zheng, Deep oxidation of 1, 2-dichlorobenzene over Ti-doped iron oxide, PCCP, 16 (2014) 12731-12740.

609

[55] X. Ma, H. Sun, H. He, M. Zheng, Competitive reaction during decomposition of

610

hexachlorobenzene over ultrafine Ca-Fe composite oxide catalyst, Catal.Lett., 119 (2007)

611

142-147.

612 613

[56] M. Kantcheva, A.S. Vakkasoglu, Cobalt supported on zirconia and sulfated zirconia: II. Reactivity of adsorbed NOx compounds toward methane, J.Catal., 223 (2004) 364-371.

614

[57] S.L. Alderman, G.R. Farquar, E.D. Poliakoff, B. Dellinger, An infrared and X-ray

615

spectroscopic study of the reactions of 2-chlorophenol, 1, 2-dichlorobenzene, and

616

chlorobenzene with model CuO/silica fly ash surfaces, Environ.Sci.Tec., 39 (2005)

617

7396-7401.

618

[58] D. Carmello, E. Finocchio, A. Marsella, B. Cremaschi, G. Leofanti, M. Padovan, G. Busca,

619

An FT-IR and Reactor Study of the Dehydrochlorination Activity of CuCl2/γ-Al2O3-Based

620

Oxychlorination Catalysts, J.Catal., 191 (2000) 354-363.

621 622 623

[59] Q. Dai, S. Bai, Z. Wang, X. Wang, G. Lu, Catalytic combustion of chlorobenzene over Ru-doped ceria catalysts, Appl. Catal. B, 126 (2012) 64-75. [60] A. Aranzabal, M. Romero-Sáez, U. Elizundia, J.R. González-Velasco, J.A. González-Marcos,

624

Deactivation of H-zeolites during catalytic oxidation of trichloroethylene, J.Catal., 296 (2012)

625

165-174.

626 627 628 629 630

[61] X. Wang, L. Ran, Y. Dai, Y. Lu, Q. Dai, Removal of Cl adsorbed on Mn-Ce-La solid solution catalysts during CVOC combustion, J. Colloid Interface Sci, 426 (2014) 324-332. [62] W. Xingyi, K. Qian, L. Dao, Catalytic combustion of chlorobenzene over MnOx-CeO2 mixed oxide catalysts, Appl. Catal. B, 86 (2009) 166-175. [63] A. Aranzabal, J. González-Marcos, M. Romero-Sáez, J. González-Velasco, M. Guillemot, P.

631

Magnoux, Stability of protonic zeolites

632

2-dichloroethane), Appl. Catal. B, 88 (2009) 533-541.

633

in the catalytic oxidation of chlorinated VOCs (1,

[64] F. Bertinchamps, A. Attianese, M. Mestdagh, E.M. Gaigneaux, Catalysts for chlorinated 27 / 28



634

VOCs abatement: Multiple effects of water on the activity of VOx based catalysts for the

635

combustion of chlorobenzene, Catal. Today, 112 (2006) 165-168.

636 637 638 639

[65] C.E. Hetrick, F. Patcas, M.D. Amiridis, Effect of water on the oxidation of dichlorobenzene over V2O5/TiO2 catalysts, Appl. Catal. B, 101 (2011) 622-628. [66] Q. Dai, S. Bai, X. Wang, G. Lu, Catalytic combustion of chlorobenzene over Ru-doped ceria catalysts: Mechanism study, Appl. Catal. B, 129 (2013) 580-588.

640

[67] G. Sinquin, C. Petit, S. Libs, J. Hindermann, A. Kiennemann, Catalytic destruction of

641

chlorinated C2 compounds on a LaMnO3+δ perovskite catalyst, Appl. Catal. B, 32 (2001)

642

37-47.

643

[68] S. Marie-Rose, T. Belin, J. Mijoin, E. Fiani, M. Taralunga, F. Nicol, X. Chaucherie, P.

644

Magnoux, Catalytic combustion of polycyclic aromatic hydrocarbons (PAHs) over zeolite

645

type catalysts: Effect of water and PAHs concentration, Appl. Catal. B, 90 (2009) 489-496.

28 / 28


Page 28 of 28

Catalytic Oxidation of Chlorobenzene over Mn - ACS Publications

Recommend Documents