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Dr. vora ppt chapter 4 aftertreatment
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This is a part of Lecture Series on Automotive Fuels & Emissions for M. Tech Students at ARAI ACADEMY.

This is a part of Lecture Series on Automotive Fuels & Emissions for M. Tech Students at ARAI ACADEMY.

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  • Together with Emitec, we evaluated the potential of such a preturbo catalyst, shown here on the picture in the left upper corner. The addition of these catalysts to the standard system allowed on a modern diesel car to further improve the tailpipe emissions by about 30 %, as is apparent from the cumulated emissions over the NEDC, the red line with preturbo catalyst and the blue line with only the standard system

Dr. vora ppt chapter 4 aftertreatment Presentation Transcript

  • 1. Catalytic Converters Dr. K. C. Vora     
  • 2. Importance of Environment & Technologies Environment Technologies 2010 System Integration Energy consumptionImportance Functions 2000 Electronics d System Integrate Emission CO2 1990 ics Electron Emission CO/HC/NOx m lic Syste Hydrau year year
  • 3. Air Quality Impact of the Catalytic ConverterMore than 8x108 tons of combinedHC, CO, NOx were abated by 2000References: Heck and FarrautoMonograph: Vora & Ghosh.
  • 4. Great success stories are continuing 100 % Engine Exhaust The development of automotive emission control technology over the > 98 % last three and a half decades is one of the greatest environmental success <2% stories of this century. O2 H2O CO2 Compared to the 1960s the emission N2 Catalyst of motor vehicles has dropped to a fraction, the fuel economy has doubled.< 0.05 % O2 > 1.95 % H2O CO2 HC N2 CO NOx
  • 5. A Catalytic Converter• Catalytic converters transform NOx, CO and HC into N2, CO2 and H2O Can or shell Mat Ceramic Substrate with Catalytic Coating N2 CO2 H2O NOX CO HC
  • 6. Functional Diagram of a Catalytic Converter
  • 7. The overall catalytic reactions
  • 8. The overall catalytic reactionsOXIDATION:2CO + O2 2CO2Hydrocarbons + O2 CO2 + H2O2H2 + O2 2H2OREDUCTION:NO + Hydrocarbons N2 + CO2 + H2O2NO + 2CO N2 + 2CO22NO + 2H2 N 2 + H2 O2NO + 5H2 2NH3 + 2H2OCO + H2O H2 + 2CO2H2O + Hydrocarbons H2 + 2CO2
  • 9. Working: Theory of Active Sites The Energy Path of a Catalysed & Uncatalysed Reaction.The active site may be viewed as the point on the catalyst material crystalline where theelectronic forces are optimum for the catalytic reaction to take place.CO and O2 are chemisorbed on the catalyst and can react readily because of their proximity andorientation. The process of adsorption also results in weakening of the bond between the atomswithin the CO molecule because some of the energy is shared with the surface. Thus, theadsorbed atoms of the molecules are less tightly bonded to the molecule and more easilyattracted to other atoms such as oxygen. The reaction between CO and oxygen is thus easierand more rapid. The products having achieved a lower energy state must desorb at the sametemperature, freeing the active site for additional reactions.
  • 10. CONSTRUCTIONS OF CATALYTIC CONVERTERS
  • 11. Partners for production of Catalytic ConvertersSUBSTRATE MANUFACTURERS:Ceramic: Corning, NGK,Silicon Carbide: IbidenMetallic: Emitec, ShowaCOATERS:Johnson Matthey, BSF (Engelhard), Umicore (Degussa),Sud-Chemie (Vadodara)SUBSTRATE+COATING: Kemira (Finland)MAT MANUFACTURERS:3M, UNIFRAXCANNERS:Sharda Motors, Walker Exhaust (Tenecco), ARVIN Exhaust
  • 12. Types of Catalytic Converters
  • 13. PALLETIZED CATALYTIC CONVERTER
  • 14. Ceramic Substrates: Unique Extrusion ProcessRange:300 to 900 CPSI.2 to 6 mil wallthickness(1 mil = 25.4microns)
  • 15. Substrate Composition Upper Temp. r Shock Strength Trade Name Manufacturer Limit, °C ResistanceCordierite 2MgO.2Al2O3.5SiO2 1200 +++ ++ Tliermacomb795 Amer. Lava  1200 +++ ++ Celcor 9475 Poramic Corning  1200 +++ ++ Versagrid W.R.Grace  1400 ++ ++ NGKMullite 3Al2O3.SiO2 1350 1700 + ++ Torvex DuPont + ++ CoorsZirconia Zr02 2200 ++ ++ - CorningSilicon SiC 1650 ++ +++ Spectram-icRX384 Ibedin,carbide NortonSilicon Si3N4 1540 ++ +++ Spectram-icRX384 NortonnitrideMetallic Fe, 20 Cr, 5 Al with 1400 +++ ++ Aluchrome Y, Emitec addition of 0.05% Kantiial KY Metal yttrium)Metallic Fe-Cr-Al-Yt 1250 +++ ++ Fecralloy Johnson Matthey, Showa CHARACTERISTICS OF SOME COMMERCIAL MONOLITHS 
  • 16. Metallic Substrates:Unique High Temp Vacuum Brazing
  • 17. HISTORY OF METALLIC SUBSTRATES
  • 18. High cell density metal substratesIf the cell density is increased with the same constructionsize, the effective surface is enlarged accordingly.This considerably increases the efficiency of the system.Range: 50 to 1000 CPSI / 0.03 to 0.05 mm foil thickness.
  • 19. ELECTRICALLYHEATEDCATALYSTS (EHCs)FROM DIFFERENTMANUFACTURERS
  • 20. TURBULENT METALLIC SUBSTRATES These foils generate turbulence in the exhaust gas stream and so greatly increase the efficiency of the catalyst.Types:•Radial flow near the wall inthe channels (TS design®)•A reduction of diffusionpaths and the hydraulicdiameter and a repeat of theentrance flow (LS design)•Radially open, perforatedstructures (PE designTM)•A combination of PE andLS structures.
  • 21. METALLIC & CERAMIC SUBSTRATES
  • 22. EXHAUST BACK PRESSURE OF METALLIC v/s CERAMIC SUBSTRATE
  • 23. Cell Density (cpsi) 200 300 400 236Cell Shape Square Square Square TriangleWall Thickness (inch) 0.0105 0.0105 0.0065 0.0115 (6.5 mil)Hole Size (inch) 0.060 0.0475 0.0435 0.042GSA(in2/in3) 48 57 70 56Density (gins/ins3) 7.90 9.60 6.74 9.63Open Frontal Area (%) 73 68 76 62 COMPARISON OF GEOMETRIC PROPERTIES OF CERAMIC MONOLITHS 
  • 24. DATA  METALLIC  CERAMIC  SUBSTRATE  SUBSTRATE    Wall thickness (mm) (uncoated)  0.04  0.2-0.15      Cell density (epsi)  400  400      Clear cross section (%)  91.6  67.1-76.0  (uncoated)      Specific surface area(m2/})  3,2  2.4-2.8      Thermal conductivity(W/m.K)  14-22  0,1-0.8      Heat capaeity (kJ/kg.K)  0.5  1.05      Density (g/cm3)  7.4  2.2-2.7      Coefficient of Thermal  15  1  expansion (AL/LxlO"6/K)      Max. short duration operating  1500  1200  temperature(°C)       COMPARISON BETWEEN METALLIC & CERAMIC SUBSTRATES
  • 25. Parameters  Ceramic cell density  Metallic cell   (cpsi)  density (cpsi)       200  300  400  400  500  600              Cell area, mm2  2.30 1.43 1.21  1.50 1.10  0.97              Surface to volume ratio,  189 220 2790  323 3580 3940 m"1  0  5    0            Open Frontal Area, %  70  60  76  89  86  83              Wall thickness, mm  0.28 0.30 0.15  0.05 0.05  0.05               COMPARISON BETWEEN CERAMIC AND METAL SUBSTRATE PARAMETERS 
  • 26.   Pt  Pd  Rh       Mine Ratio, upper Deposit  100  40  8 Catalyst Ratio, 1989 TWC  100  0  20        Approx, Cost in U.S,$/oz in 1989  600  140  1300        Approx. Cost in U.S,$/oz in 1994 [38]  400  140  800          DISPARITY OF PGM RATIOS AND COSTS
  • 27. MICROSCOPTC STRUCTURE OF A COATED TYPE CATALYST
  • 28. BENCH TEST COMPARISON OF BASE METAL V/S NOBLE METAL CATALYST
  • 29. Sr.  Noble Metal  Non-Noble Metal oxides No. 1.  Technology well-known and proven.   ot commercially proven so far.  N2.  Pt-Pd as 2 way converter catalyst.  Perovskite  oxides  LaCoOs/LaMnOs,   Lai-xSixCoi-yMyOs complex oxides. 3.  Pt-Pd/Rh  proven  combination  for  3  -way Binary Cu-Cr oxide not established My.   converter  (Ratio  10:1,  Europe  5:1,  Mine   Ratio 16.5:1),   4.  Lower  light-off  temp.,  active  even  at Active from 250°C onwards.   100°C.   5.  Conversion  efficiency  high  at  high Conversion  efficiency  tends  to  flatten   temperatures.  out  at  high  temperatures,  but    modifications are equally active. 6.  Narrow  A/F  for  efficient  3-way NO + CO-»1/2N2 + CO2  Possible in two   conversion.  stages. 7.  Not  tolerant  to  high,  continuous  Pb  level Could  be  made  Pb-tolerant  by  a  right   in gasoline.  catalyst formulation. 8.  Not  affected  by  SO2  (20  ppm  SO2  in Poisoned  by  SO2.  Development  of  SO2   exhaust for 0.03 wt% S in gasoline).  resistant formulations. 9.  Ceramic  substrate,  washcoated  with No  Washcoat  on  ceramic  substrate.   alumina  and  deposited  with  Pt/Rh  (0. Direct  deposition  of  Oxide  precursors.  16/0.03 wt%Pt/Rh).  (5-15 wt% as oxides).  COMPARISON OF NOBLE V/S. NON-NOBLE CATALYST 
  • 30. CLAMSHELLCANNING OF CATALYTICCONVERTER(Alternative method isTerniquette)
  • 31. REQUIREMENT OF CATALYTIC CONVERTER 
  • 32. PARAMETERS WHICH INFLUENCE        THE CONVERSION EFFICIENCY 
  • 33. CAUSE –EFFECT DIAGRAM FOR CATALYTIC DURABILITY 
  • 34. FOUR WINDOWS OF CATALYTIC CONVERTER OPERATIONS 
  • 35. INSTALLATION OF A METALLIC CONVERTER IN SILENCER
  • 36. EFFECIENCY SCAN AN IMPORTED CATALYTIC CONVERTER
  • 37. EFFECT OF EXHAUST PIPE LENGTH ON EXHAUST GAS TEMPERARURE 
  • 38. EXHAUST GAS TEMPERATURE BEFORE & AFTER CONVERTER
  • 39. ENDURANCE TEST OFA NOBLE METAL CATALYTIC CONVERTER ON A CAR RUN WITH LEADED PETROL
  • 40. PHOTOGRAPAPHS WITH ELECTRON MICTOSCORE AND ELECTRON DEFFRACTION
  • 41. X-RAY DIFFRACTION CHARTS 
  • 42. DETERIORATION & REJUVENATION OF CATALYTIC CONVERTER
  • 43. SCHEMATIC SET-UP FOR CATALYTIC CONVERTER TESTING 
  • 44. DUAL-LINE VEHICLE EMISSION TEST SYSTEM FOR CATALYTIC CONVERTER TESTING 
  • 45. MASS EMISSION TEST SET UP ON CHASSIS DYNAMOMETER
  • 46. LAMBDA SENSOR
  • 47. EFFECTIVENESS OF CLOSED-LOOP &OPEN-LOOP THREE-WAY CATALYSTS 
  • 48. EMISSION DATA OF 4-STROKE ENGINEDMOTORCYCLE FITTED WITH CATALYTIC CONVERTER
  • 49. EMISSION DATA OF 2-STROKE ENGINED MOPED FITTED WITH CATALYTIC CONVERTER 
  • 50. MICROSTRUCTURE OFA FRESH METALLIC MICROSTRUCTURE OFA FRESH CERAMIC CONVERTER  CONVERTER  MICRO STRUCTURE AFTER WASHCOAT ADHESION TEST  MICROSTRUCTURE OFA FRESHCERAMIC CONVERTER AFTER SOME MICROSTRUCTURE SHOWING HOURS OF ENGINE RUN  POISONING BY CONTAMINANATS 
  • 51. System Development Methodology
  • 52. Advances in Automotive ExhaustCatalysis Air-fuel management Cold-start strategies Catalyst formulation
  • 53. (Heywood)
  • 54. “Staying in the Window”
  • 55. Closed-loop control with HEGO sensor & fuel injection (Eastwood)
  • 56. Gasoline Emissions Standards - Comparison Achievable Today
  • 57. Automotive SubstratesEnabling Technology for Ultra-Low Emissions 400/6.5 (Euro 2) 900/2 (Euro 4)
  • 58. Catalyst light-off (A/F ≥ 14.7):
  • 59. Automotive Emissions Importance of Cold Start Tailpipe HC Emissions (FTP Bag 1) 0.025 1500Tailpipe HC Mass (g/s) Temperature, (Deg F) 0.02 1200 0.015 900 Catalyst "Light-Off" X Temperature 0.01 600 0.005 300 0 0 0 100 200 300 400 500 Time (s)
  • 60. Pre-turbo catalysts (PTC)PTC systemReference: Converter Spec. PTC PTC 0.04 L, 200 cpsi, 100 gpcf Pt CCC 0.9 L, 400 cpsi, 70 gpcf Pt CCC UFC 1.2 L, 400 cpsi, 90 gpcf Pt Ref. CCC 0.7 L, 400 cpsi, 70 gpcf Pt 2nd 1 Underfloor st Underfloor UFC1 1.0 L, 400 cpsi, 90 gpcf Pt catalyst UFC1 catalyst UFC2 1.2 L, 400 cpsi, 54 gpcf Pt UFC2 60
  • 61. Pre-turbo catalysts (PTC) ... Impact of pre-turbo catalyst (PTC1) on CO emission during NEDC 5.0 4.0 RawCumulative CO emission [g] Emission post Hybrid-catalyst (CC1) Emission post pre-turbo- (PTC1) and Hybrid-catalyst (CC1) 3.0 2.0 150 Velocity [km/h] 100 1.0 50 0.0 0 0 200 400 600 800 1000 Time [s] 61
  • 62. Pre-turbo catalysts (PTC) ... Emission results of reference, compared with and w.o. PTC 0,05 Ref: Standard exhaust system CCC / UFC1 / UFC2; fresh Without PTC: CC1 / UC1; fresh 0,042 0,04 0,040NEDC emission [g/km] With PTC: PTC1 / CC1 / UC1; fresh 0,033 0,03 0,021 0,02 0,016 0,015 0,015 0,015 0,01 0,010 0,00 HC CO/10 NOx/10 62
  • 63. Trends of Catalytic Converter Configuration
  • 64. Advantages of Close Coupled Catalyst (Umicore)
  • 65. Closed Couple Catalyst Design Criteria
  • 66. Exhaust System
  • 67. Characteristics of PGM Catalysts
  • 68. Improvement in Oxygen Storage Capacity
  • 69. Thank You….