CATALYTIC

CONVERTER

PRESENTED BY:-

PARTH BATRA

11BME1066

Introduction

Now a days pollution is a major cause of concern and automobiles

are heavily contributing to it.

The exhaust gases coming from cylinder is mixture of NO2 ,CO and HC

which needs to be filtered in order to reduce its detrimental effects

in atmosphere.

The filtering device used here for this purpose is called Catalytic Converter.

It is located between exhaust valve and muffler.

What is catalytic converter ?

A catalytic converter is a device that uses a catalyst to convert

three harmful compounds in car exhaust into harmless compounds.

The three harmful compounds are:

Hydrocarbons (in the form of unburned gasoline)

Carbon monoxide (formed by the combustion of gasoline)

Nitrogen oxide (created when the heat in the engine forces nitrogen in the

air to combine with oxygen)

In this catalytic converter there are two types of catalyst-oxidizing(platinum

and palladium) and reducing(platinum and rhodium).

Construction

Contd

Metallic core converter

Ceramic core converter

The core is often a ceramic honey comb in modern catalytic converter but stainless steel foil honeycombs are used too.

The honey comb surface provides more area to support the catalyst, so called catalyst support also.

The wash coats as a mixture of silica and alumina used to enhance performance of converter.

The wash coat when added ,the core forms irregular and rough surface which has more surface area than flat surface do, thus providing a more surface area for precious metal to attach.

The catalyst is added to the wash coat before being applied to the core.

Contd..

Platinum and rhodium are two other precious metals used .

Platinum and palladium are used as an oxidizing catalyst.

Cerium ,iron , manganese and nickel are also used.

WORKING:-

Contd.

Contd.

Contd.

REACTIONS INSIDE CONVERTER:-

NOx Nx + Ox Reduction of nitrogen oxides into elemental nitrogen and oxygen.

Oxidation of carbon monoxide to carbon dioxide. CO + O2 CO2

Oxidation of hydrocarbons into carbon dioxide and water. CxH4x + 2xO2 xCO2 + 2xH2O

Thermodynamics of catalytic

converters

FAILURE REASONS OF CATALYTIC

CONVERTER

EXCESS FUEL ENTERING EXHAUST:-When unburnt fuel goes in exhaust system i.e. in the catalytic converter its burning releases amount of heat that raises the inside temperature of catalytic converter , more than its meting point causing it to melt down.

OIL OR ANTIFREEZE ENTERING EXHAUST:- Oil or Antifreeze entering the exhaust system can block the air passages by creating heavy carbon soot that coats the ceramic catalyst.

OXYGEN SENSOR NOT FUNCTIONING PROPERLY:- An oxygen sensor failure can lead to incorrect readings of exhaust gasses. The faulty sensor can cause a too rich or too lean condition. Too rich and the catalyst can melt down. Too lean and the converter is unable to convert the hydrocarbons into safe elements and may not pass a state inspection.

FAILURE REASONS OF CATALYTIC

CONVERTER

ROAD DAMAGE OR BROKEN HANGERS:- Due to debris collision with

converter the ceramic catalyst is fractured, the broken pieces become

loose and rattle around and break up into smaller pieces. Flow is interrupted

and backpressure in the exhaust system increases, this leads to heat build

up and loss of power. Possible causes of a catalyst fracture are road debris

striking the converter, loose or broken hangers,off-road driving.

USING LEAD PETROL:- After burning lead petrol ,it leaves a residue that coats

the catalytic metals (Pt, Rh, Pd) and prevents them from contacting the

exhaust fumes and performing the necessary redox reactions.

Failed catalytic converter

How do I know my catalytic converter

has failed

Here are five signs that something may be wrong with your catalytic

converter:-

Your vehicles fuel efficiency suddenly drops.

Your vehicle doesnt accelerate when you step on the gas pedal.

Your vehicle may refuse to start.

Your vehicle fails an emissions test.

The MIL or Check Engine light comes on.

What happens if catalytic converter is

removed

Cost of Catalytic Converter

company name cost

Honda civic catalytic converter $185.39

Nissan Altima catalytic converter $299.65

Toyota Sienna catalytic converter $258.66

Hyundai Santa Fe catalytic converter $167.31

Cadillac CTS catalytic converter $154.84

Thank you