Preparation of LaMnO3 for catalytic combustion of vinyl chloride

Chinese Journal of Catalysis 38 (2017) 1406 1412 催化学报 2017 年第 38 卷第 8 期 www.cjcatal.org available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/chnjc Article Preparation of LaMnO3 for catalytic combustion of vinyl chloride Li Wang a, Hongkai Xie a, Xingdan Wang a, Guizhen Zhang b, Yanglong Guo a, Yun Guo a, *, Guanzhong Lu a a Key Laboratory for Advanced Materials and Research Institute of Industrial Catalysis, School of Chemistry & Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China b Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China A R T I C L E I N F O A B S T R A C T Article history: Received 11 April 2017 Accepted 12 May 2017 Published 5 August 2017 Keywords: LaMnO3 Vinyl chloride Catalytic combustion Low temperature Preparation method LaMnO3 was prepared by citrate sol gel, coprecipitation, hard template, and hydrothermal methods, respectively, and its catalytic performance for the combustion of vinyl chloride was investigated. N2 adsorption desorption, X ray diffraction (XRD), Raman spectroscopy (Raman), O2 temperature programmed desorption (O2 TPD), H2 temperature programmed surface reaction (H2 TPR) and X ray photoelectron spectroscopy (XPS) were used to characterize the physicochemical properties of the LaMnO3 samples. The preparation methods had obvious effects on the distribution of oxygen and manganese species on the catalyst surface. The reaction followed the suprafacial mechanism; the activity corresponded with the high amount of Mn 4+ and adsorbed oxygen species. LaMnO3 prepared by the citrate sol gel method had the best performance for vinyl chloride combustion with T90 of 182 C. The optimal activity was attributed to the improved redox capability of Mn 4+ /Mn 3+. More available adsorbed oxygen and Mn 4+ species on the surface were mainly responsible for the remarkable enhancement of the catalytic activity. 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved. 1. Introduction Chlorinated volatile organic compounds (CVOCs) are widely used as solvents and intermediates in the chemical industry. Consequently, the emission of CVOCs has caused great concern owing to environmental protections [1]. CVOCs are the most harmful organic pollutants because of their acute toxicity and high environmental stability [2,3]. Vinyl chloride (VC) is the main raw material used in the industrial production of polyvinyl chloride (PVC). The concentration of VC in the exhaust is 1% 2%, but only 5 ppm of VC is permitted in the US according to increasing stringent environment limitations [4]. Controlling the emission of VC has become more and more important. Catalytic oxidation, with low levels of energy consumption and high purification efficiency, is a promising technology for CVOCs emission control compared with direct incineration. The transition metal oxide catalysts, particularly perovskite type oxides (ABO3), are potential catalysts in CVOCs removal because of the wide range of resources and their good thermal stability, especially lanthanum manganese perovskite oxide (LaMnO3) [5]. Texture property and chemical state play important roles in the activity of LaMnO3. High surface area mesoporous LaCoO3 oxides with well crystallized perovskite framework shows relatively high catalytic activity [6]. The three dimensionally ordered macroporous (3DOM) of LaMnO3 has shown to be supe * Corresponding author. Tel/Fax: +86 21 64253703; E mail: yunguo@ecust.edu.cn This work was supported by the National Basic Research Program of China (2013CB933201), the National Natural Science Foundation of China (21207037, 21577035) and the Commission of Science and Technology of Shanghai Municipality (15DZ1205305). DOI: 10.1016/S1872 2067(17)62863 8 http://www.sciencedirect.com/science/journal/18722067 Chin. J. Catal., Vol. 38, No. 8, August 2017

Li Wang et al. / Chinese Journal of Catalysis 38 (2017) 1406 1412 1407 rior to the bulk counterpart [7], especially in solid solid gas reactions [8]. Meanwhile, porous spherical LaMnO3 and cubic LaMnO3 nanoparticles are good candidate catalytic materials [9]. Grain boundaries on polycrystalline epitaxial thin films of LaSrMnO3 may not only facilitate fast oxygen diffusion but also fast oxygen exchange kinetics [10]. Substitution of metal ions in ABO3 or preparing nonstoichiometric ABO3 are important ways to change the composition and symmetry while still in its native form. The T90 of the A substituted (La0.8Ce0.2MnO3) or B substituted LaMnO3 (LaB0.2Mn0.8O3) shifted to low temperature during the combustion of vinyl chloride [11,12], and this was also confirmed by the A substituted LaMnO3 (La1 xalxmno3) in 1,2 dichloroethane oxidation [13]. The enhanced oxygen mobility of nonstoichiometric La0.8MnO3 promoted the removal of Cl species on the catalyst surface [14]. The texture property and chemical state of LaMnO3 closely depend on the preparation method. In this work, LaMnO3 perovskite oxides were prepared by various methods [15 17], and catalytic oxidation of vinyl chloride was used as a model reaction. N2 adsorption desorption, X ray diffraction (XRD), Raman spectroscopy (Raman), inductively coupled plasma (ICP), O2 temperature programmed desorption (O2 TPD), H2 temperature programmed surface reaction (H2 TPR), and X ray photoelectron spectroscopy (XPS) were used to characterize the physicochemical properties of the samples. The correlation between the activity and physicochemical properties of the samples was investigated. 2. Experimental 2.1. Catalysts materials and preparation methods Metal nitrates were used as precursors to prepare LaMnO3 perovskite type oxides. An aqueous mixture of citric acid and metal nitrates of La and Mn was heated to a sol at 80 C, dried at 120 C for 12 h, and calcined at 700 C for 3 h to obtain LaMnO3, which was denoted as LMO SG. A NaOH and Na2CO3 solution mix was added dropwise to the aqueous La and Mn nitrates and kept the ph value of 10. The precipitate aged at room temperature for 4 h and was then filtered and washed. After drying at 120 C for 12 h, the precipitate was calcined at 700 C for 3 h and denoted as LMO CP. The sample prepared using the mesoporous silica KIT 6 as a template was named as LMO HT. For the hydrothermal treatment, a mixture of KOH, La, and Mn nitrate solution was kept into a teflon lined autoclave at 200 C for 24 h; the product was washed and dried at 120 C for 12 h, calcined at 700 C for 3 h, and denoted as LMO HM. A solution of KMnO4 was added dropwise to aqueous MnSO4; after the KMnO4 solution was added, the solution continued to stir for 1 h and was then filtered and washed. After vacuum drying at 100 C for 12 h, the product was denoted as MnO2. A solution of Na2CO3 was added dropwise to the aqueous Mn nitrates, and the ph value remained at 10. The precipitate aged at room temperature for 4 h and was then filtered and washed. After drying at 120 C for 3 h, it was calcined at 650 C for 3 h and denoted as Mn2O3. 2.2. Catalyst characterization Nitrogen adsorption desorption at low temperature (196 C) was performed on a NOVA 4200e surface area and porosity analyzer. The specific surface area (SSA) was obtained by the Brunauer Emmett Teller (BET) method. The powder XRD measurements were performed on a Bruker AXS D8 Focus diffractometer with Cu Kα radiation (40 kv, 40 ma, λ = 0.154 nm) at a scanning rate of 6 /min. The average crystallite sizes of the catalysts were evaluated using the Scherrer equation. Inductively coupled plasma atomic emission spectroscopy (ICP AES) was carried out on a Varian 710 ES instrument to determine the chemical compositions. O2 TPD and H2 TPR were carried out on commercial equipment (Penxiang Co., Tianjing, China). A 50 mg sample was saturated with O2 for 40 min at 30 C and then purged by He to remove the unstable adsorbed O2 and residual O2 in the pipeline. The signal of desorbed oxygen (m/z = 32) was recorded by online mass spectrometry when heating the sample from 30 to 600 C at a ramp of 10 C/min. In H2 TPR experiments, a sample was heated in a flow of 5% H2 95% N2 from ambient temperature to 450 C at a rate of 10 C/min. The amount of H2 consumption was measured by a thermal conductivity detector (TCD) with the H2 consumption with CuO as the reference for quantitative analysis. The XPS spectra were acquired with an AXIS Ultra DLD spectrometer using Mg Kα (hν = 1253.6 ev) radiation. Charged samples were avoided by setting the binding energy of adventitious carbon (C 1s) to 284.8 ev. Raman spectra were recorded with a thin wafer on a Renishaw spectrometer using a 514.5 nm Ar + laser as the excitation source at room temperature. The laser beam intensity and the spectrum slit width were 3 mw and 2 cm 1, respectively. 2.3. Catalytic activity measurement The activity test was carried out in a continuous flow fixed bed quartz reactor with 6 mm I.D. The catalyst (40 60 mesh) was packed in the reactor, and the catalytic activity measurement was carried out in the temperature range from room temperature to 500 C at 1% VC 99% N2 and controlled by a mass flowmeter that was diluted by air to reach a VC concentration of 1000 ppm at GHSV of 15000 h 1. The conversion of VC was obtained by an on line gas chromatograph (Minrui 2060) equipped with a flame ionization detector (FID). A quadrupole mass spectrometer (INFICON IPC400) was used to detect other by products. 3. Results and discussion 3.1. Catalytic performance for VC oxidation Catalytic behaviors of the samples for catalytic combustion of VC were tested and shown in Fig. 1. T50 and T90 (the temperatures at 50% and 90% VC conversion, respectively) for all of the catalysts were between 150 240 C and 218 281 C, re

1408 Li Wang et al. / Chinese Journal of Catalysis 38 (2017) 1406 1412 Conversion (%) 100 80 60 40 20 LMO-SG LMO-CP LMO-HT LMO-HM MnO 2 Mn 2O 3 0 50 100 150 200 250 0 A 0 50 100 150 200 250 300 350 400 100 80 60 40 20 Temperature ( o C) Fig. 1. VC catalytic combustion over different samples. 0 1st MnO2 2nd MnO2 1st LaMnO3 2nd LaMnO3 10 20 30 40 50 60 70 80 2/( o ) La(OH) 3 Fig. 2. XRD patterns of samples LMO SG, LMO CP, LMO HT, LMO HM. spectively. A mass spectrometer was used to identify the by products. Only HCl, Cl2, CO2, and H2O were detected, and the other chloric hydrocarbons were not found. It was shown that the preparation had obvious effects on VC removal. The T50 of the samples shifted to high temperature according to the following sequence: LMO SG < LMO CP < LMO HT < LMO HM. LMO SG exhibited the highest activity with T90 of 182 C, which was almost 100 C lower than that of LMO HM. The activity of Mn oxides (MnO2 and Mn2O3) was also tested, and the results are shown in Fig. 1. Compared with Mn2O3, MnO2 possessed excellent performance during VC combustion. VC was completed converted over MnO2 at 190 C, whereas complete conversion over Mn2O3 occurred at 410 C. The aforementioned result indicated that higher Mn valent values led to higher activity. Unfortunately, MnO2 had poor stability shown in the insert of Fig. 1; T50 of the second run was 80 C higher than that of the first run. Unlike MnO2, there was no obvious temperature difference in T50 of the two runs of LMO SG. 3.2. XRD and physicochemical properties Table 1 Physicochemical properties of the samples. Sample The XRD patterns of the samples are shown in Fig. 2. Only single phases were found in the XRD patterns, except for that of LMO HM. The characteristic diffraction peaks of La(OH)3 species were detected in LMO HM at 2θ of 27.3, 28.0, and 39.5, which were ascribed to La(OH)3 species. The presence of this hydroxide attributed to the hydroxylation of the lanthanum present in the sample upon exposure to atmospheric humidity [18]. The characteristic diffraction peaks at 22.9 (101), 32.7 (121), 40.2 (220), and 52.6 (103), which correlated with LaMnO3.15, were found in LMO SG, LMO HM, and LMO HT. The main peaks of sample LMO CP at 23.1 (012), 32.8 (104), 40.3 (202), 52.7 (122) indicated that it had a LaMnO3.26 (JCPDS#50 0299) perovskite structure. In addition, the average crystallite sizes of the samples calculated by the Scherrer equation were in the range of 15.7 to 21.2 nm. Specific surface areas and metal concentrations are summarized in Table 1. According to ICP analysis, the molar ratios of La and Mn atoms for all samples were nearly equal to the theoretical values. Preparation methods had obvious effects on the surface areas. LMO HM had the lowest surface area, which was only 15.7 m 2 /g, while the surface area of LMO HT was almost 3 times higher than that of LMO HM. 3.3. Raman spectroscopy Raman is very sensitive and used to investigate the structure of oxides and the chemical environment. Two peaks were determined from Raman analysis (Fig. 3); the intensive one located at 665 cm 1 related to the extension of Mn O in MnO6 units [19], and the other peak at 485 cm 1 reflected the extension and compression of Mn O bond pairs. A more intensive peak at 665 cm 1 was observed with LMO HM compared with the other samples. The peak at 485 cm 1 was linked with Jahn Teller distortion [20], which correlated with the ratio of Mn 4+ /Mn 3+ on the catalyst surface. The coordination oxygen atoms of Mn 3+ O6 can form a Jahn Teller distorted octahedral, whereas Mn 4+ ions in Mn 4+ O6 units have almost undistorted coordination [21]. The more severe the Jahn Teller distortion, the higher concentration of Mn 3+ presented in LaMnO3. 3.4. O2 TPD dxrd (nm) SSA a (m 2 / g) (La/Mn) b Specific reaction rates c (10 9 mol/(m 2 s)) LMO SG 15.7 47.1 0.99 0.60 LMO CP 18.1 22.3 1.02 0.55 LMO HT 18.7 50.4 0.98 0.14 LMO HM 19.6 15.7 1.01 0.11 a Measured by N2 adsorption desorption. b Chemical composition from ICP AES results. c Calculated from VC reaction rate at 150 C. O2 TPD was performed to investigate the adsorption

Li Wang et al. / Chinese Journal of Catalysis 38 (2017) 1406 1412 1409 0 500 1000 1500 2000 Wavenumber (cm 1 ) Fig. 3. Raman patterns of samples LMO SG, LMO CP, LMO HT, LMO HM. amount and the rate of oxygen activation on the sample surface. Oxygen desorption profiles below 600 C are displayed in Fig. 4, as the catalytic combustion of vinyl chloride usually occurred below 500 C. Desorption peaks in the range of 150 450 C were ascribed to the weaker molecular physisorbed and/or chemisorbed oxygen [22], Oα, on the sample surface. Oα are regarded as the most active species in the reaction of catalytic oxidation. Meanwhile, the amount of Oα was also used to characterize the concentration of oxygen vacancy on the surface or subsurface, which played an important role in exchange and transformation between gas oxygen and lattice oxygen [23]. To compare the relative amount of the O2 desorption amount, the O2 desorption peak area of LMO SG was set as 1.00 as shown in Table 2. The results suggested that the amount of adsorbed O2 species was related to the preparation method. 3.5. H2 TPR 485 665 H2 TPR profiles of the samples are shown in Fig. 5. The H2 consumption amount, summarized in Table 2, was calculated Table 2 The data obtained from H2 TPR and O2 TPD analysis. Catalyst H2 consumption a (mmol/g) Total α β γ Area of Oα b (10 8 ) LMO SG 1.49 0.29 0.86 0.34 1.00 LMO CP 1.46 0.27 0.78 0.41 0.94 LMO HT 1.27 0.26 0.72 0.29 0.83 LMO HM 1.19 0.15 0.67 0.37 0.71 a Obtained from H2 TPR. b Obtained from O2 TPD. using CuO as a reference. A small peak and a broad peak with a shoulder were found in the range of 100 250 C and 250 500 C, respectively. Three peaks were obtained by deconvolution; α was ascribed to removing physically adsorbed oxygen and/or the ordinarily chemically adsorbed oxygen, β was attributed to the nonstoichiometric excess oxygen accommodated within the lattice, and γ was due to the reduction of Mn 4+ to Mn 3+ or the single electron reduction of Mn 3+ located in a coordination unsaturated microenvironment [24]. Compared with the other samples, the reduction temperature of LMO SG was shifted to a lower temperature. The reduction α of LMO SG was only 232 C, which was 22 C lower than that of LMO HM. The temperature difference for the reduction of β between LMO SG and LMO HM was larger, approximately 40 C. There was not much difference in the total H2 uptake between LMO SG and LMO CP; while the total H2 uptake of LMO HM decreased up to 20% compared with LMO SG. The H2 consumption of α and β was consistent with the following sequence: LMO SG > LMO CP > LMO HT > LMO HM. 3.6. XPS Mn 2p and O 1s XPS spectra are illustrated in Fig. 6, and the integration of the corresponding peaks allowed us to determine the atomic ratios of surface species (Table 3). A broad and asymmetrical Mn 2p3/2 peak at 642 ev and Mn 2p1/2 peak at 652 ev were observed in Fig. 6(a). By deconvoluting the Mn 2p3/2 and Mn 2p1/2 peaks, it was found that Mn 232 338 406 230 328 389 216 311 377 298 210 363 100 200 300 400 500 Temperature ( o C) Fig. 4. O2 TPD patterns of samples LMO SG, LMO CP, LMO HT, LMO HM. 100 200 300 400 500 Temperature ( o C) Fig. 5. H2 TPR patterns of samples LMO SG, LMO CP, LMO HT, LMO HM.

1410 Li Wang et al. / Chinese Journal of Catalysis 38 (2017) 1406 1412 (a) Mn 2p Mn 3+ Mn 4+ (b) O 1s O latt O ads H 2 O Mn 2p 3/2 Mn 2p 1/2 635 640 645 650 655 660 526 528 530 532 534 536 538 Bingding energy (ev) Bingding energy (ev) Fig. 6. XPS patterns of samples. (a) Mn2p, (b) O 1s. LMO SG, LMO CP, LMO HT, LMO HM. species were mainly in the form of Mn 4+ and Mn 3+ [25 27]. The surface La/Mn ratio of all samples was higher than the theoretic La/Mn atomic ratio, indicating a La surface enrichment. The extent of La enrichment on surface correlated with the preparation method. Despite the surface La enrichment in LMO SG, LMO CP, and LMO HT, XRD analysis did not reveal the presence of diffraction peaks attributed to lanthanum oxide (La2O3) or lanthanum oxycarbonate ((LaO)2CO3); this could be due to the low quantity of those species on the sample surface. The ratio of La/Mn on LMO HM was two times higher than that of the theoretic La/Mn atomic ratio, indicating the formation of new La species. The surface enrichment of lanthanum was ascribed to lanthanum (oxy/hydroxy) carbonate [28]. The detection of La(OH)3 by XRD on LMO HM confirmed the abovementioned speculation. The highest ratio of Mn 4+ /Mn was found on LMO SG, which meant that there were more Mn 4+ species on the surface of LMO SG. In Fig. 6(b), the asymmetrical O 1s spectra of each sample was de convoluted to three peaks: the first peak at 529.4 529.7 ev corresponded to lattice oxygen Olatt (O 2 ) in the oxide network; the second peak at 531.1 531.4 ev was ascribed to the surface adsorbed Oads (O, O2 or O2 2 ) from hydroxyl or carbonate groups, and the third peak at 533 ev was due to the adsorbed molecular water [29]. The oxygen species and the distribution varied with the manner by which the samples were prepared. The LMO SG had the highest Oads/Ototal molar ratio among all the samples, while the LMO HM had the lowest ratio. The ranking in terms of Oads/Ototal molar ratio was in agreement with the results of H2 TPR and O2 TPD experiments. Combined with the analysis of Mn species, it was found the molar ratio of Oads/Ototal followed the same sequence as that of Mn 4+ /Mn 3+. Particularly, the concentration of surface oxygen vacancies (λ = 3.15 Olatt/(La + Mn)) were calculated using the XPS results (Table 3). The oxygen vacancies existed on the perovskite corroborating with the O2 TPD results. Meanwhile, the λ value was in line with the catalytic activity. This indicated that surface oxygen vacancies played an important role in oxidation reaction since they were responsible for the adsorption desorption properties of the gas phase, and they facilitated the diffusion of lattice oxygen from the bulk to the surface. 3.7. Discussion The preparation method decided the morphology, redox properties, and chemical states of the catalysts; compared with the first factor, the last two factors played a more important role in deciding the catalytic activity of LaMnO3 perovskite type materials in the oxidation reaction. The nature of redox usually dominated the active oxygen species and oxygen activation, while the chemical state of the active species was consistent with the adsorption and activation of reactant. LaMnO3 perovskite oxides were synthesized by citrate sol gel, co precipitation, hard template, and hydrothermal methods, and catalytic performances were evaluated for VC oxidation. The poor activity of LMO HM was assigned to the presence of La(OH)3 on the surface. Although LMO HT, prepared by using KIT 6 as template, had the largest specific surface area, it still led to fewer active oxygen species on the surface. In the process of preparing sample by citrate sol gel, citric Table 3 XPS results of the samples. Sample (La/Mn) a Mn a (%) (Mn 4+ /Mn 3+ ) a (Oads/Ototal) a Olatt/(La+Mn) a λ b LMO SG 1.28 12.26 1.33 0.44 1.06 1.03 LMO CP 1.51 9.60 1.24 0.42 1.14 0.87 LMO HT 1.45 9.86 1.13 0.39 1.33 0.49 LMO HM 2.29 6.75 0.99 0.38 1.54 0.07 a Obtained from XPS. b As defined in the literature [30].

Li Wang et al. / Chinese Journal of Catalysis 38 (2017) 1406 1412 1411 acid acted as a complexing agent, which increased the solubility of metal ions and helped maintain homogeneity by preventing selective precipitation, leading to the smallest obtained crystallite size. LMO SG exhibited the highest activity with T90 of 182 C. From H2 TPR profiles (Fig. 5) and H2 uptake (Table 2), the total H2 consumption in the low temperature range for the reduction of the adsorbed oxygen species varied with the catalyst preparation. From the O2 TPD study (Fig. 4) and XPS analysis (Table 3), more desorbed oxygen species indicated that more oxygen vacancies were generated and participated in the oxygen migration process. The amount of adsorbed oxygen species and the rate of the oxygen activation followed the same sequence as that of the catalytic activity. The VC combustion occurred at low temperature (< 300 C), so adsorbed oxygen was the dominant oxygen species participating in this reaction, namely the reaction followed the suprafacial mechanism. Raman spectra (Fig. 3) showed the variance in the distribution of Mn 3+ on all the samples, and XPS (Fig. 6) characterization also confirmed that the molar ratio of Mn 4+ /Mn 3+ on the surface increased in the same sequences as the amount of oxygen vacancies. The first step of the reaction is adsorption; a higher amount of adsorption sites was on the surface, thereby activating a higher amount of reactant. The activity tests of MnO2 and Mn2O3 confirmed that the high valence of Mn provided the active sites for VC adsorption and activation (Fig. 1). However, LaMnO3 exhibited better stability than MnO2, indicating that LaMnO3 was a good catalyst candidate for future practical application. 4. Conclusions LaMnO3 perovskite oxides were synthesized by citrate sol gel, co precipitation, hard template, and hydrothermal methods, and the catalytic performances were evaluated for VC catalytic oxidation. LaMnO3 SG prepared using the citrate sol gel method exhibited the best performance in catalytic combustion of VC with T90 of 182 C and stability. The reaction followed the suprafacial mechanism, and no co relation was found between surface area and activity. The ratio of Mn 4+ /Mn 3+ and its redox ability differed based on catalyst preparation. The enrichment of Mn 4+ benefited the adsorption and activation of VC, and the presence of oxygen vacancies facilitated the adsorption of oxygen. The improved redox capability of Mn 4+ /Mn 3+ guaranteed the supply of active oxygen species. More available adsorbed oxygen and Mn 4+ species on the surface were mainly responsible for the remarkable enhancement of the catalytic activity. References [1] E. D. Goldberg, Sci. Total Environ., 1991, 100, 17 28. [2] F. Alonso, I. P. Beletskaya, M. Yus, Chem. Rev., 2002, 102, 4009 4092. [3] M. Gallastegi Villa, M. Romero Sáez, A. Aranzabal, J. A. González Marcos, J. R. González Velasco, Catal. Today, 2013, 213, 192 197. [4] M. Hiraoka, S. Sakai, T. Sakagawa, Y. Hata, Organohalogen Compd., 1997, 31, 446 453. [5] S. H. Liang, T. G. Xu, F. Teng, R. L. Zong, Y. F. Zhu, Appl. Catal. B, 2010, 96, 267 275. [6] Y. X. Wang, X. Z. Cui, Y. S. Li, Z. Shu, H. R. Chen, J. L. Shi, Microporous Mesoporous Mater., 2013, 176, 8 15. [7] Y. X. Liu, H. X. Dai, Y. C. Du, J. G. Deng, L. Zhang, Z. X. Zhao, C. T. Au, J. Catal., 2012, 287, 149 160. [8] J. F. Xu, J. Liu, Z. Zhao, G. Z. Zhang, A. J. Duan, G. Y. Jiang, C. M. Xu, Chin. J. Catal., 2010, 31, 236 241. [9] Y. Z. Wang, S. H. Xie, J. G. Deng, S. X. Deng, H. Wang, H. Yan, H. X. Dai, ACS Appl. Mater. Interfaces, 2014, 6, 17394 17401. [10] E. Navickas, T. M. Huber, Y. Chen, W. Hetaba, G. Holzlechner, G. Rupp, M. Stöger Pollach, G. Friedbacher, H. Hutter, B. Yildiz, J. Fleig, Phys. Chem. Chem. Phys., 2015, 17, 7659 7669. [11] C. H. Zhang, W. C. Hua, C. Wang, Y. L. Guo, Y. Guo, G. Z. Lu, A. Baylet, A. Giroir Fendler, Appl. Catal. B, 2013, 134 135, 310 315. [12] C. H. Zhang, C. Wang, Z. W. Zhan, Y. L. Guo, Y. Guo, G. Z. Lu, A. Baylet, A. Giroir Fendler, Appl. Catal. B, 2013, 129, 509 516. [13] S. X. Chen, Y. Wang, A. P. Jia, H. H. Liu, M. F. Luo, J. Q. Lu, Appl. Surf. Sci., 2014, 307, 178 188. [14] Y. J. Lu, Q. G. Dai, X. Y. Wang, Catal. Commun., 2014, 54, 114 117. Graphical Abstract Chin. J. Catal., 2017, 38: 1406 1412 doi: 10.1016/S1872 2067(17)62863 8 Preparation of LaMnO3 for catalytic combustion of vinyl chloride Li Wang, Hongkai Xie, Xingdan Wang, Guizhen Zhang, Yanglong Guo, Yun Guo *, Guanzhong Lu East China University of Science and Technology; Beijing University of Technology 90% vinyl chloride conversion was obtained at 182 C on LaMnO3. More available adsorbed oxygen and Mn 4+ species on the surface were mainly responsible for the enhancement of catalytic activity. Temperature of 90% VC conversion ( C) C 2 H 3 Cl + 5/2O 2 2CO 2 + H 2 O + HCl Preparation method of LaMnO 3 Mn 4+ /Mn 3+ ratio

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