Appendix A. Supplementary data

Preparation of metal-doped Cu-Mn/HTS-1 catalysts and their mechanisms in

efficient degradation of toluene

Jianrui Niu, Haobin Liu, Hengli Qian, Jie Liu, Mengyuan Ma, Erhong Duan*, Lei Yu*

School of Environmental Science and Engineering, Hebei University of Science and Technology, Hebei 050018, ChinaPollution Prevention Biotechnology Laboratory of Hebei Province, Hebei 050018, China

-----------------------------* Corresponding authors. E-mails: duan_eh@163.com (Erhong Duan), yuleimail@163.com (Lei Yu)

Catalyst characterizationThe crystal structures of the prepared catalysts were characterized using X-ray diffraction analysis performed on a Rigaku X-ray diffractometer (XRD) operated with Cu Kα radiation. Scanning

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electron microscopy (SEM) and transmission electron microscopy (TEM) images of the samples were obtained with a Hitachi S-4800 and a JEOL JEM 2100 instrument, respectively. The surface composition and binding energy (BE) of Mn2p and O1s were determined by X-ray photoelectron spectroscopy (XPS, ESCALAB 250XI). The compositions of the catalysts were investigated using an Agilent Technologies 7900 ICP-MS apparatus. The by-products issued from the toluene oxidation were analyzed using a Shimadzu Technologies Chromatograph Mass Spectrometer apparatus (GCMS-TQ8040).

Catalytic conversion for combustion of tolueneTable S1 Catalytic conversion for combustion of toluene reported in the literatures.

Catalyst Method Oxidation Conditions Conversio

n

Refere

nce

Mn-AC Co-precipitation 500 ppm toluene and synthetic air

(20% O2); 60000 ml·g-1·h-1

T50=249°C (Zhang

et al., 2019)

GLC-15 gunpowder-like

combustion

1000 ppm toluene and synthetic

air (20% O2); 30000 ml·g-1·h-1

T50=248°C (Yang

et al., 2019)

Co3O4-400 Template method

thermal decomposition

ZIF-67

12000 ppm toluene and synthetic

air (20% O2); 21000 ml·g-1·h-1

T50=243°C (Zhao,

et al., 2019)

Cu0.7Mn2Ce0.3Ox/

HTS-1

Co-precipitation 2000 ppm toluene and synthetic

air (20%O2); 10000 ml·g-1·h-1

T50=230°C This

work

Quantitative analysis of catalystsTable S2 Quantitative analysis of CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1.

Catalyst Loading amount %

Actual

Molar ratio : Cu/Mn/Ce or Y

Nominated Actual

CuMn2O4/HTS-1 4.9 0.70/2.00/0.00 0.94/2.00/0.00

Cu0.7Mn2Y0.3Ox/HTS-1 5.1 0.70/2.00/0.30 0.68/2.00/0.31

Cu0.7Mn2Ce0.3Ox/HTS-1 4.7 0.70/2.00/0.30 0.71/2.00/0.32

The quantitative reports demonstrate the actual loading amount of catalysts in Table S1. This is quite close to the nominated metal content in catalysts. The subtle change of metal content detected for the catalyst could be attributed to the error produced by the catalyst digestion in during pretreatment of ICP-MS test.

TEM morphologies

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Fig. S1 TEM morphologies of CuMn2O4/HTS-1 (a-c) and Cu0.7Mn2Y0.3Ox/HTS-1 (d-f).

valence distribution of Mn speciesThe intensities of Mn4+ characteristic peaks increased with the decrease of Cu content, which was caused by the degree of electron transfer occurring between the Mn 3+ and Mn 4+ in spinel. If the Cu content of CuMn2O4 decreases, it means that the amount of Mn content is excessive. Some of the relatively excess Mn species generated a valence change to maintain the electrical neutrality of spinel, and others were introduced into the lattice of CeO2 in the form of Mn3+ and Mn4+. To further study the Mn species valence distribution, the calculation process of Mn species valence distribution in catalysts can be expressed as follows:

m+n=z (1)

m+2a1bn+2a2b

=c1

c2 (2)

In which m, n are amount of Mn3+, Mn4+ into the CeO2 (Y2O3) lattice in 1 mol sample, respectively; z is excess amount of Mn species that escape from the spinel in 1 mol samples; a1, a2

are the content of Mn3+, Mn4+ in the spinel sample without CeO2 addition respectively; b is amount of Cu species in 1 mol sample; c1, c2 are content of Mn3+, Mn4+ in the sample, respectively.m and n were obtained in Table S3.

Table S3 Calculation results of Mn species valence distribution

Catalyst b c1 c2 z m (mol) n (mol)

Cu0.7Mn2Y0.3Ox/HTS-1 0.7000 0.7524 0.2476 0.6000 0.2692 0.3308

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Cu0.7Mn2Ce0.3Ox/HTS-1 0.7000 0.6891 0.3109 0.6000 -0.1181 0.7181

As shown in Table S3, the m,n values of Cu0.7Mn2Y0.3Ox/HTS-1 is positive and m, n＜z, confirming that the increase in Mn4+ in Cu0.7Mn2Y0.3Ox was mainly derived from the fact that the excess Mn content in spinel to maintain the electroneutrality of spinel system. For Mn species entering the inside of the Y2O3 lattice, it mainly exists in the form of Mn3+ and Mn4+; The m values of Cu0.7Mn2Ce0.3Ox/HTS-1 is negative and m＞ z, there were two paths to remove the excess Mn content from the CuMn2O4. Some of the Mn species did not escape the spinel with the amount of Cu content decreased. The Mn3+ to Mn4+ transition occurred in the spinel to maintain the electroneutrality of spinel. Other Mn species were introduced to the CeO2 lattice in the form of Mn4+. As a result of this case, the introduction of Mn4+ to CeO2 was easier to induce the labile Ce3+/Ce4+ cycle that promote electron transfers and hence improving the interaction between CuMn2O4 and CeO2.

MVK model dataThe kinetic model can be expressed as follows:

-ri= KiCiθ (3)

-roi=KoiCoi (1-θ) (4)

In which θ is coverage rate of the surface oxidation activity of the catalyst; -ri, -roi are reaction rate of VOCs and oxygen consumption (mol·(cm3·s)-1), respectively; Ki, Koi are the rate of catalyst surface reduction and oxidation reaction(s-1), respectively; And Ci, Coi are the concentration of VOCs and oxygen (mol·(cm3)-1), respectively. 1 mol VOCs were oxidized to consume αi mol oxygen, and we can calculate -roi = -αi-ri. The measured reaction rate was corrected for this approach based on the above equations.

1ri

=α i

K oiCoi+ 1

K iC i (5)

In the reaction, the concentration of oxygen is much higher than toluene. Therefore, it can be considered that the conversion of oxygen is constant, i.e., A=-αi/koiCoi. The equation can be simplified as:

1ri

=A+ 1K iC i

(6)

Fitting with 1/-ri and 1/Ci, the rate constant can be calculated by the slope and intercept of the fit line.

ln K=−ER T

+ A (7)

Fitting with 1/-ri and 1/Ci, the activation energy can be obtained by Eq. (7).

The effect of toluene concentration on the reaction rate of toluene degradation is described in Table 4. The ri (reaction rate) and ci (toluene concentration) were brought into Eq. (6) to calculate Ki.

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Table S4 Effect of toluene concentration and reaction concentration on the degradation rate and catalytic rate of

CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1.

Temperature (K) Toluene concentration

（10-8 mol·(cm3)-1）Conversion

(%)

Reaction rate

(10-8 mol·(cm3·s)-1)

CuMn2O4/HTS-1

463.15 4.012 2.4 0.082 6.032 2.2 0.111

8.065 1.9 0.123

10.11 1.7 0.133

473.15 4.087 3.5 0.122

6.069 3.3 0.162

8.62 3.0 0.203

10.052 2.8 0.216

483.15 4.115 4.3 0.167

6.188 4.1 0.238

8.123 3.8 0.295

10.099 3.4 0.334

493.15 4.012 6.8 0.220

6.045 6.5 0.318 8.102 6.4 0.400

10.103 6.0 0.465

Cu0.7Mn2Y0.3Ox/HTS-1

445.15 4.015 5.2 0.220 6.102 4.9 0.314

8.035 4.7 0.396

10.061 4.4 0.463

456.15 4.114 6.7 0.295

6.081 6.3 0.409

8.043 6.0 0.513

10.028 5.7 0.606

467.15 4.067 8.0 0.354

6.071 7.8 0.514

8.109 7.5 0.657

10.096 7.2 0.783

478.15 4.012 9.6 0.426

6.068 9.3 0.622

8.023 8.9 0.784

10.072 8.6 0.948

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Cu0.7Mn2Ce0.3Ox/HTS-1

413.15 4.025 3.6 0.442 6.087 3.3 0.611

8.102 2.9 0.712

10.115 2.5 0.763

423.15 4.109 5.2 0.663

6.001 4.8 0.890

8.065 4.4 1.092

10.152 3.9 1.212

443.15 4.136 7.4 0.972

6.188 6.9 1.349

8.202 6.3 1.622

10.001 5.7 1.778

463.15 4.012 9.7 1.268

6.088 9.2 1.814

8.146 8.9 2.341

10.147 8.2 2.666

Table S5 Effect of toluene concentration and reaction concentration on the degradation rate and catalytic rate of

CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1.

Temperature (K) Toluene concentration

（10-8 mol·(cm3)-1）Conversion

(%)

Reaction rate

(10-8 mol·(cm3·s)-1)

CuMn2O4/HTS-1

463.15 3.012 1.9 0.172 5.035 1.6 0.241

7.065 1.4 0.295

9.105 1.2 0.325

473.15 3.068 2.8 0.260

5.067 2.4 0.366

7.041 2.2 0.466

9.108 2.0 0.547

483.15 3.005 3.8 0.349

5.118 3.6 0.562

7.019 3.3 0.705

9.007 3.1 0.847

493.15 3.063 5.1 0.484

5.018 4.8 0.744 7.038 4.6 0.998

9.09 4.3 1.201

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Cu0.7Mn2Y0.3Ox/HTS-1

445.15 3.012 5.0 0.466 5.103 4.6 0.724

7.085 4.4 0.959

9.067 4.0 1.111

456.15 3.091 6.4 0.622

5.081 6.1 0.971

7.109 5.8 1.287

9.091 5.5 1.556

467.15 3.022 7.9 0.762

5.034 7.7 1.235

7.109 7.4 1.671

9.113 7.1 2.048

478.15 3.085 9.4 0.941

5.076 9.1 1.495

7.038 8.8 1.997

10.072 8.4 2.717

Cu0.7Mn2Ce0.3Ox/HTS-1

413.15 3.018 3.4 0.312 5.062 3.0 0.460

7.042 2.7 0.575

9.031 2.6 0.709

423.15 3.102 5.1 0.490

5.099 4.7 0.740

7.024 4.3 0.928

9.002 4.0 1.103

443.15 3.134 7.3 0.726

5.084 6.8 1.091

7.001 6.2 1.361

9.012 5.8 1.632

463.15 3.089 9.5 0.954

5.069 9.1 1.493

7.108 8.8 2.017

9.043 8.5 2.471

Catalyst life of Cu0.7Mn2Ce0.3Ox/sepiolite

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Fig. S2 Catalyst life of Cu0.7Mn2Ce0.3Ox/sepiolite: catalytic temperature was 190℃(a) and 270℃(b).

Redox properties and oxidation states of catalysts

Fig. S3 H2-TPR curves for the CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1 catalysts.

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Fig. S4 XPS spectra of he CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1.

Table S6 XPS analysis of O1s in CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1.

SampleContent (%)

Osur/ Olatt

Osur Olatt

CuMn2O4/HTS-1 91.4 8.6 10.6

Cu0.7Mn2Y0.3Ox/HTS-1 90.4 9.6 9.4

Cu0.7Mn2Ce0.3Ox/HTS-1 88.6 11.4 7.8

The O species located in the CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1 catalysts were also characterized by XPS. As shown in Fig. S3 and Table 2, the O1s spectra displayed two major oxygen contributions and the corresponding peaks centered at 529.4-530.2 eV, 531.8-532.4eV. These bands can be attributed to lattice oxygen (Olat) and surface-absorbed oxygen (Osur), respectively. The lattice oxygen were nucleophilic reagents and usually responsible for selective oxidation reactions. The ratio of Osur /Olatt are approximately 10.6, 9.4 and

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7.8 for CuMn2O4/HTS-1, Cu0.7Mn2Y0.3Ox/HTS-1 and Cu0.7Mn2Ce0.3Ox/HTS-1, respectively (Table 2). A large amount of surface-adsorbed oxygen species existed on all catalysts. The reason is that there is a large number of Si-OH group on the surface of HTS-1 (as verified by FT-IR analysis, see Fig. 9). The different ratio of Osur /Olatt in the catalysts resulted from the interaction between CuMn2O4 and CeO2, which was related to the distribution of Mn ion. In the process of catalytic oxidation of toluene, toluene molecules can be activated and react with the lattice oxygen to form a reduced catalyst.

The effect of diffusion, mass transfer limitations and thermal effects.

Fig. S5 The effect of thermal effects (a), GHSV (b) and particle size (c) on the conversion of toluene.

As shown in Fig. S4a, quartz sand was used as inert material to test the catalytic activity. It showed that the reactor and inert filler have no catalytic effect on toluene. The thermal effects in the reaction process can be eliminated; When the GHSV is 5000h-1-12000h-1(Fig. S4b), the conversion of toluene was stable with the increase of GHSV, illustrated that the influence of external diffusion of reaction is basically eliminated in this range; When the particle size of the catalyst is 40-100 mesh (Fig. S4c), there is no obvious change in the conversion of toluene, indicating that the internal diffusion effect can be substantially eliminated when the catalyst particle is 40-100 mesh.

Zhang, X.J., Zhao, H., Song, Z.X., Liu, W., Zhao, J.G., Ma, Z.A., et al., 2019. Insight into the effect of oxygen species and Mn chemical valence over MnOx on the catalytic oxidation of toluene. Applied Surface Science 493, 9-17.

Yang, J.S., Li, L.M., Yang, X.S., Song, S., Li, J., Jing, F.L., et al., 2019. Enhanced catalytic performances of in situ-assembled LaMnO3/δ-MnO2 hetero-structures for toluene combustion. Catalysis Today 327, 19-27.

Zhao, J.H., Tang, Z.C., Dong, F., Zhang, J.Y., 2019. Controlled porous hollow Co3O4 polyhedral nanocages derived from metalorganic frameworks (MOFs) for toluene catalytic oxidation. Molecular Catalysis 463, 77-86.

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