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Catalytic converter


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Catalytic converter

  2. 2.  Automobiles contribute major air quality problems in rural as well as urban and industrialized areas.  About 50 million cars are produced every year.  Over 700 million cars are used worldwide.  Vehicle population is projected to grow close to 1300 million by the year 2030.
  3. 3.  All Automobile vehicle which are used gasoline, diesel and jet fuels they have large amount of emission of :  carbon monoxide (CO),  unburned hydrocarbons (HC),  nitrogen oxides (NOx)  particulates matter (PM) are especially concern .  Reason for occurance :  HC and CO occur because the combustion efficiency is less than 100%.  The NOx is formed during the very high temperatures (>1500 0C) of the combustion process.
  4. 4.  Typical exhaust gas composition at the normal engine operating conditions are:  carbon monoxide (CO, 0.5% vol.).  unburned hydrocarbons (HC, 350 vppm).  nitrogen oxides (NOx, 900 vppm)  hydrogen (H2, 0.17% vol.).  water (H2O, 10% vol.).  carbon dioxide (CO2, 10% vol.).  oxygen (O2, 0.5 %vol.).
  5. 5.  As the emission standards were tightened, more advanced control strategies were applied that included  modifications in engine design and  fuel system, control of engine parameters and  use of sophisticated exhaust after treatment devices .  Reduction of toxic substances emission from combustion engines can be achieved by  primary (inside engine) measure and  secondary (outside engine) measures.  Nowadays secondary measures, in automotive exhaust aftertreatment processes a range of advanced technology is applied based on oxidation and three-way catalyst adsorption storage and filtration process.
  6. 6.  It was in 1991 that first time emission norms were introduced in India for petrol cars, diesel cars followed in 1992.  Emission norms means some rules (which has specified quantity) decided by the govt for control of air pollution .  Implementation of mandatory catalytic converters in 1995 for the 4 Metro cities, thus reducing pollution further.  From 2000, India introduced strict Emission standards modeled on the European ones. This means the birth of Bharat Norms, with the first set of norms known as Bharat Stage II, followed by BS III, and BS IV (BS I was the earlier, Indian standard).
  7. 7. GRAMS EXHAUST PER KM DRIVEN Stage Year CO HC NOx HC+NO x India Standard 1991 14.3to 27.1 2.0 to 2.9 India Standard 1996 8.68 to 12.74 3 to 4.36 India Standard 1998 4.34 to 6.20 1.5 to 2.18 India Standard 2000 2.78 0.97
  8. 8. BS 2 2001 2.2 0.5 Delhi, Mumbai, Kolkata, Chennai BS 2 Apr 05 2.2 to 5 0.5 to 0.7 Nation wide BS 3 Apr 05 2.3 0.2 0.15 NCR+12 City BS 3 Apr 10 2.3to 5.22 0.2 to 0.9 0.15 to 2.1 Nation wide BS 4 Apr 10 1 0.1 0.08 NCR+12 City BS 4 Apr 10 1to 2.27 0.1 to 0.16 0.08 to 11 Nation wide
  9. 9.  3.1 INTRODUCTION:  A catalytic converter is a device used to reduce the toxicity of emissions from an internal combustion engine.  A catalytic converter (CC) is placed inside the tailpipe through which deadly exhaust gases containing unburnt fuel, CO, NOx are emitted.  The function of the catalytic convertor is to convert these gases into CO2, water, N2 and O2 .
  10. 10. Types of Catalytic Converter:  1) 3 way catalytic converter  2) 2 way catalytic converter  3 way catalytic converter  A three-way catalytic converter has three tasks:  Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2  Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2  Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: 2CxHy + (2x+y/2)O2 → 2xCO2 + yH2O
  11. 11.  2 way catalytic converter :  A two-way catalytic converter has two tasks:  Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2  Oxidation of unburnt hydrocarbons (unburnt and partially- burnt fuel) to carbon dioxide and water: 2CxHy + (2x+y/2)O2 → 2xCO2 + yH2O
  12. 12.  The catalytic converter consists of several components:  The core or substrate: • In modern catalytic converters, this is most often a ceramic honeycomb, however stainless steel foil honeycombs are also used. The purpose of the core is to support the catalyst.  The washcoat : • In an effort to make converters more efficient, a washcoat is utilized, most often a mixture of silica and alumina. • The washcoat, when added to the core, forms a rough, irregular surface which has a far greater surface area than the flat core surface and therefore more places for active precious metal sites. • The catalyst is added to the washcoat (in suspension) before application to the core.
  13. 13.  with temperatures up to 1000 C the metal in the catalyst is prone to deactivation by sintering.  Emissions control targets is simply to increase the amount of PGM(platinum group metal’s) in the auto catalyst.  Can not function well beyond 80,000 km.
  14. 14.  Catalytic converters have also been developed for construction equipment lawn and garden equipment marine engines and other non-road engines.  Catalytic converters are also used to reduce emissions from alternative fuel vehicles powered by natural gas, methanol, ethanol and propane.  To date more than 500 million vehicles equipped with catalytic converters have been sold worldwide.  Worldwide over 90 percent of new cars sold had a catalyst.
  15. 15.  Environmental, ecological and health concern result in increasingly stringent emissions regulations of pollutant emissions from vehicle engines.  Among all the types of technologies developed so far, use of catalytic converters is the best way to control auto exhaust emission.  The economical reasons, limited resources of platinum group (noble) metal and some operating limitations of platinum group metal based catalytic converters have motivated the investigation of alternative catalyst materials.
  16. 16.  Julie M Pardiwala, Femina Patel, Sanjay Patel, "Review paper on Catalytic Converter for Automotive Exhaust Emission", INSTITUTE OF TECHNOLOGY, NIRMA UNIVERSITY, AHMEDABAD – 382 481, 08-10 DECEMBER, 2011     R.K.Rajput (IC Engine)