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Research & Application of Mixed Oxides for Selective Catalytic Reduction of NO x by Chen Zhi-hang Ph.D. Atmospheric Environment & Pollution Prevention.

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Presentation on theme: "Research & Application of Mixed Oxides for Selective Catalytic Reduction of NO x by Chen Zhi-hang Ph.D. Atmospheric Environment & Pollution Prevention."— Presentation transcript:

1 Research & Application of Mixed Oxides for Selective Catalytic Reduction of NO x by Chen Zhi-hang Ph.D. Atmospheric Environment & Pollution Prevention Research Center South China Institute of Environmental Science, MEP

2 SCIES Contents Introduction Mixed-oxide Catalysts for Industrial Boiler at High Temperature Mixed-oxide Catalysts for SCR at Low Temperature Mixed-oxide Catalysts for Glass Kilns at Middle-low Temperature Conclusions & Prospect

3 SCIES <5% 67.4% 5~10% 6.8% 10~25% 10.4% 25~50% 8.2% 50~75% 5.4% >75% 1.8% No data Frequency Area% Acid Rain Distribution in China Introduction Beijing Shanghai Guangzhou NO x emission Transportation Power Plant Others Nitrogen oxide emissions from power plants, industrial boilers, and kilns accounted for 70% in China. ( Journal of Environmental Sciences, 2008, 28(12): )

4 SCIES Technology for DeNO x DeNO x SNCR Adsorption Method SCR Electrolytic Process Plasma Method Microbial Process NH 3 NH 3 -SCR Commercialized High efficient SCR Reaction : SCRselective catalytic reduction SNCRselective Non catalytic reduction

5 SCIES Mixed-oxide Catalysts for Industrial Boiler at High Temperature

6 SCIES SCR for flue gas denitrification in power plant boilers SCR The process flow diagram of SCR denitrification in power plant boilers. SCR DeNO x Reactor in power plant boilers. Honeycomb Corrugated plate Flat V 2 O 5 -WO 3 (MoO 3 )/TiO 2

7 SCIES Flue gas denitrification pilot test Small and medium-sized boiler The honeycomb SCR catalyst developed by Tsinghua University et. al. Test device for flue gas denitrification(200 Nm 3 /h ) National High Technology Research and Development Program of China (2006 Guangdong-Hongkong Project of The Major Breakthroughs in Key Areas 2008 Major Scientific and Technological Special Project of Guangdong Province (2010

8 SCIES Demonstration projects of SCR Industrial boiler Demonstration projects of SCR denitrification (35 t/h chain-grate boiler in Pacific(Panyu) Textiles Limited, flow rate: Nm 3 /h ) SCR Denitrification tower of Pacific co. SCR DeNO x Reactor

9 SCIES Mixed-oxide Catalysts for SCR at Low Temperature

10 SCIES SCR at Low Temperature Suitable temperature for catalysis(SCR at 350~450 ) Dust (e.g., K 2 O, CaO, and As 2 O 3 ) and SO 2 deactivate the catalyst Energy efficient and cost saving Typical SCR catalyst has low activity under low temperature Novel Catalyst should be developed for low temperature SCR at 80~150

11 SCIES [1] Catal. Commun. 8 (2007) [2] Appl. Catal. A 327 (2007) 261. [3] Catal. Commun. 8 (2007) 329. [4] Appl. Catal. B 79 (2008) 347. [5] Catal. Commun. 8 (2007) [6] Angew. Chem. Int. Ed. 40 (2001) Catalysts Developed for Low-Temperature SCR [1~12] MnO x MnO x /TiO 2 CuO x -MnO x and MnO x -CeO 2 etc.. Mn-Cu/TiO 2 Mn-Cr/TiO 2 catalysts showed good activity (C NO : 60, 120 o C, NO/NH 3 =1 at 0.2%, GHSV=8,000 h -1 ) MnO x -CeO 2 exhibited well activity(100 o C, C NO :~90%, NO/NH 3 =1 at 0.2% GHSV=42,000 h -1 ) Sulfur dioxide and vapour resistant are weak. Mixed-oxide catalyst may be a kind of prospective low- temperature SCR candidates [7] Appl. Catal. B 44 (2003) 217. [8] Catal. Today 111 (2006) 236. [9] Appl. Catal. B 51 (2004) 93. [10] Appl. Catal. B 62 (2006) 265. [11] Chem. Commun. 7 (2003) 848. [12] Ind. & Eng. Chem. Res. 45 (2006) 6444

12 SCIES Screen of Low-temperature SCR Catalysts Activity of mixed oxides prepared by SR method Activity evaluation conditions:[NO]=[NH 3 ]=1000 ppm[,O 2 ]=3%,[SO 2 ]=100 ppm,GHSV=30,000 h -1 Cr-MnO x Fe-MnO x are potential catalysts

13 SCIES Cr-MnO x SCR activity at Low temperature SCR activity and XRD patterns of (a) CrO x ; (b) MnO x ; (c) CrO x -MnO x ; (d) Cr(0.5)-MnO x catalysts New crystal

14 SCIES XRD patterns and SEM images of the Cr-MnO x catalysts doped by different Cr content Cr(0.1)-MnO x Cr(0.2)-MnO x Cr(0.3)-MnO x Cr(0.4)-MnO x Cr(0.5)-MnO x Cr(0.1)-MnO x Cr(0.3)-MnO x Cr(0.4)-MnO x Cr(0.2)-MnO x

15 SCIES Mn 3 O 4 Bond length of crystals CrystalBondBond-length Mn 3 O 4 Mn-O2.2922Å Mn-O1.9475Å Mn-O2.0142Å MnOMn-O2.2215Å Cr 2 O 3 Cr-O2.0367Å Cr-O1.9458Å CrMn 1.5 O 4 Mn-O2.3509Å Cr-O1.4686Å MnO Cell of CrMn 1.5 O 4 Cr 2 O 3 CrMn 1.5 O 4 Mechanism studying Cr-MnO x Structure analysis Oxygen bridge between Cr and Mn in the form of Cr-O-Mn; Cr-O bond in CrMn 1.5 O 4 is shorter than those of CrO x Mn-O bond in CrMn 1.5 O 4 is longer than those of MnO x

16 SCIES Raman shift of CrO x in lower wave number without presenting in mixed oxides conforms the formation of new phase; New Raman shift appears and increases with the increasing of Cr content; Raman shift at and 642.7cm -1 are the characteristic shifts of Cr-O-Mn in CrMn 1.5 O 4 Raman spectra of catalysts Mechanism studying Cr-MnO x Raman spectra measurement CrOx MnOx Cr(0.1)-MnOx Cr(0.2)-MnOx Cr(0.3)-MnOx Cr(0.4)-MnOx Cr(0.5)-MnOx [13] J. Appl. Phys. 99 (2006) ; [14] Mater. Sci. Eng. B 118 (2005) 74; [15] J. Appl. Phys. 103 (2008) ; [16] J. Electrochem. Soc. 140 (1993) 3065; [17] J. Mater. Chem. 11 (2001) 1269; [18] J. Catal. 150 (1994) 94 Cr 2 O 3 [13-15 ] Mn 3 O 4 [16-18]

17 SCIES XPS spectra for (A) Mn 2p, (B) Cr 2p, and (C) O 1s of the Cr(0.4)-MnO x catalysts: (a) fresh catalyst, (b) used catalyst, (c) regenerated catalyst. Mn 2pCr 2pO 1s fresh used regenerated Mechanism studying Cr-MnO x XPS measurement

18 SCIES XPS spectra Element valence Cr(0.4)-MnO x Catalysts FreshUsed Regenerat ed Cr 2p (eV) Concn(%) Cr (13.9)575.7(16.8)575.7(19.7) Cr (42.2)576.7(49.9)576.6(38.0) Cr (43.9)578.3 (33.3)578.5(42.3) Mn 2p (eV) Concn(%) Mn (14.6)640.5(15.5)640.5(16.0) Mn (54.2)641.9(46.9)642.2(60.6) Mn (31.2)644.5(37.6)644.8(23.4) O 1s (eV) Concn(%) O (71.0)529.8(73.9)529.9(72.2) OH - /CO ( (26.1)531.8(27.8) Binding energies (eV) of core electrons of Cr(0.4)-MnO x catalysts* * Surface concentration of different Mn, Cr and O states are in parenthesis Cr 5+ Mn % 6.4% Cr 3+ Mn % 7.3% After 500h SCR Cr 5+ Mn % 13.7% Cr 3+ Mn % 14.2% Regenerated catalyst Normal pressure & temperature plasma treatment Mechanism studying Cr-MnO x XPS measurement

19 SCIES Redox catalytic cycles over Cr(0.4)-MnO x catalysts Mechanism studying mechanism elucidation Journal of Catalysis, 2010, 276: Industrial & Engineering Chemistry Research, 2012, 51: Industrial & Engineering Chemistry Research, 2014, 53: 2647 – 2655.

20 SCIES Pilot test of Low-temperature SCR The Low-temperature SCR catalyst developed by Research Center for Eco-environmental Science, CAS et. al. Test device for Low- temperature SCR (Circulating fluidized bed boiler in Guangzhou Huiteng Textiles Limited, flow rate: 5000 Nm 3 /h ) National Natural Science Foundation of China 2008 National High Technology Research and Development Program of China (2009

21 SCIES Mixed-oxide Catalysts for Glass Kilns at Middle-low Temperature

22 SCIES The process flow diagram of SCR for glass kiln. Middle-low temperature SCR for glass kilns Middle-low temperature SCR Work at 180~300 High activity Strong ability of sulfur tolerant The flue gas emission from glass kiln of China South Glass Group(Guangzhou) (The concentration of SO 2 NO x is very high(about 500~3000mg/m 3 ) The temperature of flue gas is low( 280 )

23 SCIES SCR activity of VM/TiO 2 catalysts Screen of Middle-low Temperature SCR Catalysts

24 SCIES Effects of SO 2 on NOx conversions over VM/TiO 2 catalysts at 275 o C. Reaction conditions: [NO]=[NH 3 ]=1000 ppm, [O 2 ]=3%, [SO 2 ]=600 ppm, GHSV=60,000 h -1 Effect of SO 2

25 SCIES XPS measurement 2V8Cu/TiO 2 2V12Cu/TiO 2 2V20Cu/TiO 2 2V16Cu/TiO 2 2V2Cu/TiO 2 V 4+ V 5+

26 SCIES VCuMn/TiO 2 & VCoMn/TiO 2 Catalysts SCR activity of VCuMn/TiO 2 & VCoMn/TiO 2 Catalysts VCuMn/TiO 2 VCoMn/TiO 2

27 SCIES Effects of SO 2 on NO x conversions over VCuMn/TiO 2 & VCoMn/TiO 2 catalysts at 250 o C. Reaction conditions: [NO]=[NH 3 ]=1000 ppm, [O 2 ]=3%, [SO 2 ]=600 ppm, GHSV=60,000 h -1. VCuMn/TiO 2 VCoMn/TiO 2 Effect of SO 2 Advanced Materials Research, 2012, : Journal of Fuel Chemistry and Technology, 2012, 40(4):

28 SCIES Forming of Catalysts Natural Science Foundation of Guangdong (2011 National Natural Science Foundation of China 2013 Pearl River Nova Program of Guangzhou (2014 The vacuum refining mud machine Hydraulic extruder

29 SCIES Conclusion & Prospect Localization of Commercial SCR catalyst has been made progress. How to reduce the cost of catalyst, establish of catalyst regeneration center. Novel Cr-MnO x, Fe-MnO x, Mn-Zr catalysts with well low-temperature SCR activity have been developed; If we can not solve the problem of high activity at low temperature( 120 ) should we change our thinking. Series of VMn, VCu, and modified catalysts are studying systematically. How to improve the activity of the catalyst under high concentration of SO 2 is a huge challenge.

30 Acknowlegment Ministry of Environmental Protection, China Ministry of Science Technology, China National Natural Science Foundation of China Natural Science Foundation of Guangdong, China Department of science and technology of Guangdong Province Department of science and information technology of Guangzhou South China University of Technology Thank you for your attention Thank you for your attention


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