Low Temperature Catalytic Degradation of Chlorobenzene and PCDD/Fs over VOx-MoOx/TiO2 Catalyst
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摘要: 垃圾焚烧过程中会产生大量氯苯等氯代挥发性有机污染物(CVOCs)和二噁英等持久性有机污染物(POPs). CVOCs的排放会导致光化学烟雾和温室效应的产生，而二噁英能在土壤中长期附存，具有人体致癌和致畸变等严重危害. 催化降解技术具有显著优势，能将二噁英等有机污染物彻底破坏分解，最终将其转化为CO2、H2O和HCl等产物. 基于钒基催化剂VOx/TiO2的过渡金属氧化物催化剂已被广泛应用于烟气CVOCs和二噁英处理领域. 钒基氧化物VOx中的V=O基团对二噁英起到亲核吸附的作用，在钒基氧化物上添加第二活性组分钼氧化物MoOx可以提高催化剂的催化活性. 本文采用湿法浸渍的方法制备出用于催化降解含氯污染物的粉体钒钼钛VOx-MoOx/TiO2催化剂，并分析其合成方法、催化表征和性能测试结果，讨论反应温度对一氯苯及二噁英催化率影响的机理，旨在为开发二噁英催化技术提供参考. 结果表明：VOx-MoOx/TiO2催化剂表面催化活性位点较多，活性组分分散良好，起始还原温度较低，活性氧含量较多，比表面积较大，颗粒团聚较轻，具有优良的催化特性. 通过系列实验筛选出合适的催化剂组分比例为5%VOx-5%MoOx/TiO2(记作“V5-Mo5-Ti”，即VOx和MoOx的质量分数各占5%，TiO2的质量分数占90%)，在150 ℃低温下其对一氯苯和二噁英的催化效果优异. V5-Mo5-Ti催化剂对一氯苯的低温转化率随原始稳定浓度和空速比的升高而降低. 在一氯苯初始浓度为150×10−6、空速比为10 000 h−1时，V5-Mo5-Ti催化剂在150 ℃下对一氯苯的转化率为54.0%，在300 ℃时接近100%. 在150 ℃的低温环境中，该催化剂对二噁英催化脱除率在86%以上，催化降解率在74%以上. 研究显示，VOx-MoOx/TiO2催化剂对二噁英的催化脱除率和降解率随温度的升高而提高，主要归因于升温加快了V2O5中V5+和V4+元素以及MoO3中Mo6+和Mo4+元素的催化氧化循环速率.
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关键词:
- VOx-MoOx/TiO2催化剂 /
- 一氯苯 /
- 二英 /
- 转化率 /
- 催化降解
Abstract: In the process of waste incineration, a large amount of chlorinated volatile organic pollutants (CVOCs) such as chlorobenzene and persistent organic pollutants (POPs) such as PCDD/Fs are generated. The emission of CVOCs will lead to photochemical smoke and the greenhouse effect. PCDD/Fs can exist in soil for a long time, causing serious consequences such as carcinogenesis and teratogenesis to the human body. Catalytic degradation technology has significant advantages in PCDD/Fs treatment, which can completely destroy and decompose organic pollutants and convert them into CO2, H2O, HCl and other products. Transition metal oxide catalysts based on VOx/TiO2 have been widely used in the treatment of flue gas CVOCs and PCDD/Fs. The V=O group in VOx plays the role of nucleophilic adsorption of PCDD/Fs. Adding the second active component MoOx to vanadium-based oxide can improve the catalytic activity of the catalyst. In this study, a series of powder catalysts of VOx-MoOx/TiO2 for catalytic degradation of CVOCs were prepared by wet impregnation method. The synthesis method, catalytic characterization and performance test results of VOx-MoOx/TiO2 catalyst were analyzed. The influence mechanism of reaction temperature on the catalytic degradation rate of chlorobenzene (CB) and PCDD/Fs was discussed, providing reference for expanding PCDD/Fs catalytic technology. The results show that VOx-MoOx/TiO2 catalyst has excellent catalytic activities, which is attributed to its abundant surface catalytic active sites, good dispersion of active components, low initial reduction temperature, high active oxygen content, large specific surface area, and less particle agglomeration. Through a series of experiments, the formulation of 5%VOx-5%MoOx/TiO2 (denoted as ‘V5-Mo5-Ti’, the mass fraction of VOx and MoOx respectively accounts for 5% and the mass fraction of TiO2 accounts for 90%) with the highest catalytic activities was developed, which showed excellent catalytic activities on both CB and PCDD/Fs at the low temperature of 150 ℃. The conversion rate of V5-Mo5-Ti at low temperature was increased as the initial concentration and gas hourly space velocity (GHSV) increased. When the initial concentration of CB was 150×10−6 and the GHSV was 10,000 h−1, the conversion rate of CB by V5-Mo5-Ti was 54.0% at 150 ℃ and was close to 100% at 300 ℃. At low-temperature (150 ℃), the removal rate of PCDD/Fs was higher than 86%, and the catalytic rate was higher than 74%. The research shows that the catalytic removal rate and degradation rate of PCDD/Fs by VOx-MoOx/TiO2 catalyst increased with the increase of reaction temperature, attributing to the accelerated oxidation cycle rate of V5+ and V4+ in V2O5 and Mo6+ and Mo4+ in MoO3.-
Key words:
- VOx-MoOx/TiO2 catalyst /
- chlorobenzene /
- PCDD/Fs /
- conversion rate /
- catalytic degradation
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图 9 不同温度下Mo的质量分数对V5-Mo-Ti催化一氯苯转化率的影响
Figure 9. Effect of mass fraction of Mo on the conversion of chlorobenzene catalyzed by V5-Mo-Ti at different temperatures
图 10 不同温度下稳定浓度对V5-Mo5-Ti催化一氯苯转化率的影响
Figure 10. Effect of stable concentration on the conversion of chlorobenzene catalyzed by V5-Mo5-Ti at different temperatures
图 11 不同温度下空速比对V5-Mo5-Ti催化一氯苯转化率的影响
Figure 11. Effect of space velocity ratio on chlorobenzene conversion catalyzed by V5-Mo5-Ti at different temperatures
图 12 不同温度下V5-Mo5-Ti对二噁英的催化脱除率及降解率
Figure 12. PCDD/Fs removal rate and degradation rate by V5-Mo5-Ti at different temperatures
表 1 17种有毒二英的物化参数和国际毒性当量因子(I-TEF)
Table 1. physicochemical parameters and international toxicity equivalent factor (I-TEF) of 17 toxic PCDD/Fs
异构体名称 熔点/℃ 沸点/℃ 溶解度/(mol/L) 蒸汽压/Pa I-TEF 2,3,7,8-TCDD 305 446 $ {{3.4 \times 10}}^{{-8}} $ $ {{5.8 \times 10}}^{{-5}} $ 1 1,2,3,7,8-PeCDD 240 465 $ {{7.8 \times 10}}^{{-9}} $ $ {{1.2 \times 10}}^{{-5}} $ 0.5 1,2,3,4,7,8-HxCDD 273 488 $ {{2.6 \times 10}}^{{-9}} $ $ {{3.9 \times 10}}^{{-6}} $ 0.1 1,2,3,6,7,8-HxCDD 285 488 $ {{2.2 \times 10}}^{{-9}} $ $ {{3.3 \times 10}}^{{-6}} $ 0.1 1,2,3,7,8,9-HxCDD 243 488 $ {{1.6 \times 10}}^{{-8}} $ $ {{1.4 \times 10}}^{{-6}} $ 0.1 1,2,3,4,6,7,8-HpCDD 264 507 $ {{6.8 \times 10}}^{{-10}} $ $ {{5.9 \times 10}}^{{-6}} $ 0.01 OCDD 325 510 $ {{2.5 \times 10}}^{{-10}} $ $ {{1.3 \times 10}}^{{-7}} $ 0.001 2,3,7,8-TCDF 227 438 $ {{1.3 \times 10}}^{{-7}} $ $ {{3.7 \times 10}}^{{-4}} $ 0.1 1,2,3,7,8-PeCDF 225 465 $ {{3.2 \times 10}}^{{-8}} $ $ {{6.2 \times 10}}^{{-5}} $ 0.05 2,3,4,7,8-PeCDF 196 465 $ {{2.1 \times 10}}^{{-8}} $ $ {{5.5 \times 10}}^{{-5}} $ 0.5 1,2,3,4,7,8-HxCDF 256 488 $ {{7.1 \times 10}}^{{-9}} $ $ {{1.4 \times 10}}^{{-5}} $ 0.1 1,2,3,6,7,8-HxCDF 232 488 $ {{6.0 \times 10}}^{{-9}} $ $ {{1.2 \times 10}}^{{-5}} $ 0.1 2,3,4,6,7,8-HxCDF 246 488 $ {{4.2 \times 10}}^{{-9}} $ $ {{7.6 \times 10}}^{{-6}} $ 0.1 1,2,3,7,8,9-HxCDF 239 488 $ {{2.3 \times 10}}^{{-9}} $ $ {{2.2 \times 10}}^{{-6}} $ 0.1 1,2,3,4,6,7,8-HpCDF 236 507 $ {{1.7 \times 10}}^{{-9}} $ $ {{2.5 \times 10}}^{{-6}} $ 0.01 1,2,3,4,7,8,9-HpCDF 221 507 $ {{6.3 \times 10}}^{{-10}} $ $ {{6.6 \times 10}}^{{-7}} $ 0.01 OCDF 258 507 $ {{2.3 \times 10}}^{{-10}} $ $ {{1.8 \times 10}}^{{-7}} $ 0.001 
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表 2 5种催化剂V、Mo、O结合能位置及价态占比
Table 2. Binding energy positions and valence proportion of V, Mo and O of five catalysts
催化剂 结合能/eV 价态占比 O 1s V 2p Mo 3d Oα/(Oα+Oβ) V4+/(V4++V5+) Mo4+/(Mo4++Mo6+) Oα Oβ V4+ V5+ Mo 3d5/2 Mo 3d3/2 Mo4+ Mo6+ Mo4+ Mo6+ V5-Ti 532.2 530.5 516.7 517.6 — — — — 0.31 0.27 — Mo5-Ti — — — — 232.6 233.1 235.6 236.2 — — 0.09 V5-Mo5-Ti 531.7 530.5 516.5 517.7 232.2 233.1 235.3 236.3 0.16 0.42 0.11 V5-Ce5-Ti 531.7 530.1 517.1 517.7 — — — — 0.13 0.37 — V5-W5-Ti 531.6 530.3 516.7 517.2 — — — — 0.23 0.24 —
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表 3 8种催化剂N2物理吸附表征结果
Table 3. N2 physical adsorption characterization results of eight catalysts
催化剂 BET比表面积/(m2/g) 孔体积/(cm3/g) 孔径/nm Nano-TiO2 54.63 0.18 13.18 V5-Ti 50.33 0.31 24.80 Mo5-Ti 55.81 0.39 28.31 V5-Mo5-Ti 50.80 0.28 23.30 V5-Mo2.5-Ti 51.01 0.32 25.53 V5-Mo7.5-Ti 47.51 0.32 27.26 V5-Ce5-Ti 47.25 0.36 30.06 V5-W5-Ti 48.92 0.37 28.82
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[1] 王亚韡,蔡亚岐,江桂斌.斯德哥尔摩公约新增持久性有机污染物的一些研究进展[J].中国科学:化学,2010,40(2):99-123. doi: 10.1360/zb2010-40-2-99WANG Y W,CAI Y Q,JIANG G B.Research processes of persistent organic pollutants (POPs) newly listed and candidate POPs in Stockholm Convention[J].Scientia Sinica Chimica,2010,40(2):99-123. doi: 10.1360/zb2010-40-2-99 [2] OJALA S,PITKÄAHO S,LAITINEN T,et al.Catalysis in VOC abatement[J].Topics in Catalysis,2011,54(16/17/18):1224-1256. [3] BHAVSAR S P,REINER E J,HAYTON A,et al.Converting Toxic Equivalents (TEQ) of dioxins and dioxin-like compounds in fish from one Toxic Equivalency Factor (TEF) scheme to another[J].Environment International,2008,34(7):915-921. doi: 10.1016/j.envint.2008.02.001 [4] GAO H C,NI Y W,ZHANG H J,et al.Stack gas emissions of PCDD/Fs from hospital waste incinerators in China[J].Chemosphere,2009,77(5):634-639. doi: 10.1016/j.chemosphere.2009.08.017 [5] TRITZ A,ZIEGLER-DEVIN I,PERRIN C,et al.Experimental study of the oxidation and pyrolysis of dibenzofuran at very low concentration[J].Journal of Environmental Chemical Engineering,2014,2(1):143-153. doi: 10.1016/j.jece.2013.11.030 [6] WHYLIE P,DYKE P,ALBAIGES J,et al.Regionally based assessment of persistent toxic substances:global report 2003[R].Geneva,Switzerland:UNEP Chemicals,2003. [7] RATHNA R,VARJANI S,NAKKEERAN E.Recent developments and prospects of dioxins and furans remediation[J].Journal of Environmental Management,2018,223:797-806. [8] CONNER W C Jr,FALCONER J L.Spillover in heterogeneous catalysis[J].Chemical Reviews,1995,95(3):759-788. doi: 10.1021/cr00035a014 [9] QU Z P,BU Y B,QIN Y,et al.The improved reactivity of manganese catalysts by Ag in catalytic oxidation of toluene[J].Applied Catalysis B:Environmental,2013,132/133:353-362. doi: 10.1016/j.apcatb.2012.12.008 [10] 詹金姣,张琪,孙诗白,等.低Pd负载量结构化邻二甲苯燃烧催化剂的设计[J].环境科学研究,2020,33(12):2794-2801. doi: 10.13198/j.issn.1001-6929.2020.06.04ZHAN J J,ZHANG Q,SUN S B,et al.Design of structured catalysts with low Pd loading for o-xylene combustion[J].Research of Environmental Sciences,2020,33(12):2794-2801. doi: 10.13198/j.issn.1001-6929.2020.06.04 [11] 张均,汤木娥,周易,等.钯基催化剂电催化氢解处理氯代有机物的研究进展[J].环境科学研究,2022,35(1):119-130.ZHANG J,TANG M E,ZHOU Y,et al.Progress in electrocatalytic hydrogenolysis of chlorinated organic compounds on palladium-based catalysts[J].Research of Environmental Sciences,2022,35(1):119-130. [12] YANG Z J,XIA C H,ZHANG Q,et al.Catalytic detoxification of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in fly ash[J].Waste Management,2007,27(4):588-592. doi: 10.1016/j.wasman.2006.02.019 [13] de JONG V,CIEPLIK M K,REINTS W A,et al.A mechanistic study on the catalytic combustion of benzene and chlorobenzene[J].Journal of Catalysis,2002,211(2):355-365. doi: 10.1016/S0021-9517(02)93762-0 [14] 杜翠翠.球磨法制备钒基催化剂催化降解氯苯及二噁英的基础研究[D].杭州:浙江大学,2018. [15] WEBER R,SAKURAI T,HAGENMAIER H.Low temperature decomposition of PCDD/PCDF,chlorobenzenes and PAHs by TiO2-based V2O5-WO3 catalysts[J].Applied Catalysis B:Environmental,1999,20(4):249-256. doi: 10.1016/S0926-3373(98)00115-5 [16] FINOCCHIO E,BUSCA G,NOTARO M.A review of catalytic processes for the destruction of PCDD and PCDF from waste gases[J].Applied Catalysis B:Environmental,2006,62(1/2):12-20. [17] GILARDONI F,BELL A T,CHAKRABORTY A,et al.Density functional theory calculations of the oxidative dehydrogenation of propane on the (010) surface of V2O5[J].The Journal of Physical Chemistry B,2000,104(51):12250-12255. doi: 10.1021/jp001746m [18] LOMNICKI S,LICHTENBERGER J,XU Z T,et al.Catalytic oxidation of 2,4,6-trichlorophenol over vanadia/titania-based catalysts[J].Applied Catalysis B:Environmental,2003,46(1):105-119. doi: 10.1016/S0926-3373(03)00215-7 [19] GOEMANS M,CLARYSSE P,JOANNÈS J,et al.Catalytic NOx reduction with simultaneous dioxin and furan oxidation[J].Chemosphere,2004,54(9):1357-1365. doi: 10.1016/S0045-6535(03)00255-8 [20] BERTINCHAMPS F,GRÉGOIRE C,GAIGNEAUX E M.Systematic investigation of supported transition metal oxide based formulations for the catalytic oxidative elimination of (chloro)-aromatics. part I:identification of the optimal main active phases and supports[J].Applied Catalysis B:Environmental,2006,66(1/2):1-9. [21] HUANG L Y,SU G J,LIU Y X,et al.Effect of NiFe2O4 on PCDF byproducts formation during thermal degradation of decachlorobiphenyl[J].RSC Advances,2014,4(48):25453. doi: 10.1039/c4ra02580f [22] 李敏,付丽亚,谭煜,等.Mn-Ce/γ-Al2O3催化臭氧氧化深度处理石化废水中试研究[J].环境科学研究,2021,34(10):2380-2388.LI M,FU L Y,TAN Y,et al.Pilot study of advanced treatment of petrochemical wastewater by Mn-Ce/γ-Al2O3 catalytic ozonation[J].Research of Environmental Sciences,2021,34(10):2380-2388. [23] BONTE J L,FRITSKY K J,PLINKE M A,et al.Catalytic destruction of PCDD/F in a fabric filter:experience at a municipal waste incinerator in Belgium[J].Waste Management,2002,22(4):421-426. doi: 10.1016/S0956-053X(02)00025-9 [24] 胡志健,安璐,李永光.焦化厂SCR脱硝催化剂积碳失活研究[J].环境工程技术学报,2020,10(2):192-196. doi: 10.12153/j.issn.1674-991X.20190112HU Z J,AN L,LI Y G.Study on coking deactivation of SCR denitration catalyst in a coke-oven plant[J].Journal of Environmental Engineering Technology,2020,10(2):192-196. doi: 10.12153/j.issn.1674-991X.20190112 [25] CHO C H,IHM S K.Development of new vanadium-based oxide catalysts for decomposition of chlorinated aromatic pollutants[J].Environmental Science & Technology,2002,36(7):1600-1606. [26] ZHAN M X,YU M F,ZHANG G X,et al.Low temperature degradation of polychlorinated dibenzo-p-dioxins and dibenzofurans over a VOx-CeOx/TiO2 catalyst with addition of ozone[J].Waste Management,2018,76:555-565. doi: 10.1016/j.wasman.2018.02.049 [27] 俞明锋.VOx-CeOx/TiO2催化剂低温降解二噁英的基础研究[D].杭州:浙江大学,2017. [28] WANG J,WANG X,LIU X L,et al.Kinetics and mechanism study on catalytic oxidation of chlorobenzene over V2O5/TiO2 catalysts[J].Journal of Molecular Catalysis A:Chemical,2015,402:1-9. doi: 10.1016/j.molcata.2015.03.003 [29] KRISHNAMOORTHY S,RIVAS J A,AMIRIDIS M D.Catalytic oxidation of 1,2-dichlorobenzene over supported transition metal oxides[J].Journal of Catalysis,2000,193(2):264-272. doi: 10.1006/jcat.2000.2895 [30] 蔺卓玮.钒钼体系列中低温SCR脱硝催化剂的研究[D].北京:华北电力大学(北京),2017. [31] SING K S W.Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984)[J].Pure and Applied Chemistry,1985,57(4):603-619. doi: 10.1351/pac198557040603 [32] ZHOU X J,LI X D,MA X H,et al.Adsorption of polychlorinated dibenzo-p-dioxins and dibenzofurans vapors on activated carbon[J].Environmental Engineering Science,2014,31(12):664-670. doi: 10.1089/ees.2014.0084 [33] ZHOU X J,LI X D,NI M J,et al.Removal efficiencies for 136 tetra- through octa-chlorinated dibenzo-p-dioxins and dibenzofuran congeners with activated carbons[J].Environmental Science and Pollution Research,2015,22(22):17691-17696. doi: 10.1007/s11356-015-4940-6 [34] ZHAO X Y,ZENG X L,QIN Y,et al.An experimental and theoretical study of the adsorption removal of toluene and chlorobenzene on coconut shell derived carbon[J].Chemosphere,2018,206:285-292. doi: 10.1016/j.chemosphere.2018.04.126 [35] 周旭健.多孔碳材料对二英吸附特性的机理研究[D].杭州:浙江大学,2016. [36] 周旭健,李晓东,徐帅玺,等.多孔碳材料对二英吸附性能的研究评述及展望[J].环境污染与防治,2016,38(1):76-81. doi: 10.15985/j.cnki.1001-3865.2016.01.014ZHOU X J,LI X D,XU S X,et al.Dioxins adsorption on porous carbon materials:a review[J].Environmental Pollution & Control,2016,38(1):76-81. doi: 10.15985/j.cnki.1001-3865.2016.01.014 [37] 籍龙杰.典型含氯化合物对催化降解氯苯和二英的影响机理研究[D].杭州:浙江大学,2017. [38] WU Y X,LIANG H L,CHEN X,et al.Effect of preparation methods on denitration performance of V-Mo/TiO2 catalyst[J].Journal of Fuel Chemistry and Technology,2020,48(2):189-196. doi: 10.1016/S1872-5813(20)30010-4 -
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