This document discusses catalytic converters and their role in reducing vehicle emissions. It notes that catalytic converters use precious metals to convert harmful exhaust gases like carbon monoxide, unburned hydrocarbons, and nitrogen oxides into less harmful emissions. Stricter emission standards over time have led to advances in catalytic converter design and materials. The document provides details on the components and chemical reactions that occur in both two-way and three-way catalytic converters.

1. SANTOSH YADAV
MTECH (EE)
NIT WARANGAL(AP)

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.  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.  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.  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.  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. 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. 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.  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 .

11. 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

12.  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

13.  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.

14.  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.

15.  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.

16.  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.

17.  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
 www.cpcb.nic.in
 www.wikipedia.com
 www.scribd.com
 R.K.Rajput (IC Engine)