Chemistry Project

Methods of reducing air pollution

Methods of reducing air

pollution of motor cars

Catalytic Converters

( 催化轉化器 )

Catalytic converters

-For cars using unleaded petrol( 無鉛汽油 )

-Convert toxic air pollutants (e.g. CO, NO) in the exhaust to harmless substances (e.g. CO2, water)

-Contain catalysts( 催化劑 ) to speed up the reactions

Catalytic converters- Become ineffective when poisoning or hea

t deactivation occur

Poisoning causes by– lead, sulphur, zinc, manganese, silicon or phosphorus

Heat deactivation causes by– Lubricating oil– Engine misfire or ignition failure– A cracked exhaust valve

Reducing Pollutants From Motor Cars

By Using Environmental Fuels

Reducing Pollutants From Motor Cars

By Using Environmental Fuels

Using Unleaded Petrol

• unleaded petrol comes in combination with the use of a catalytic converter.

• transform noxious exhaust gases into less undesirable gases.

The Hong Kong government banned the sale of leaded petrol in 1999

**Car exhaust gas contains a mixture of lead compounds which may cause serious lung diseases!

Reducing Pollutants From Motor Cars

By Using Environmental FuelsLLiquefied iquefied PPetroleum etroleum GGasas • Pollution from motor vehicles is controlled Pollution from motor vehicles is controlled

through fuel and emission control.through fuel and emission control.• The Hong Kong government tried to The Hong Kong government tried to

encourage taxi operators to encourage taxi operators to replace replace diesel taxi with those operated on LPGdiesel taxi with those operated on LPG

A LPG taxi

By regulationControl excessive emissions of smoke from car

Air Pollution Control Ordinance

At 1990 At 1990 Prohibits the use of Prohibits the use of high sulphur content solhigh sulphur content solidid and and liquid fuelliquid fuel for commercial and indust for commercial and industrial appliances. rial appliances.

At1994At1994 Prohibits the sale of Prohibits the sale of leaded petrol leaded petrol

At 2003At 2003 Requires pre-Euro light diesel vehicles to Requires pre-Euro light diesel vehicles to have have emission reduction devices.emission reduction devices.

During During

publicpublic

consultatioconsultationn

Proposal to Ban Idling Vehicles with Proposal to Ban Idling Vehicles with Running EngineRunning Engine

Individual method to reduce air pollutants

• Using low sulphur content petrol or diesel oil

• Using unleaded petrol• Installation of catalytic converter

s in car exhaust systems• Switching off the engines of idling

vehicles • Taking public transport

Government strategies• More stringent fuel and

vehicle emission standards. • Encouragement to adopt

cleaner alternatives to diesel vehicles, such as the use of Liquefied Petroleum Gas for taxis and light buses.

• Installation of old diesel vehicles with devices that, reduce emissions such as particulate traps or catalytic converters.

• Promotion of better vehicle maintenance and eco-driving habits.

Results of strategies

Ways to reduce air

pollution of industries

Scrubber( 裝置滌氣器 )

Scrubber( 裝置滌氣器 )

Use of Scrubber :

． can remove up to 95% of SO2 ( 二氧化硫 ).

． Scrubbers mainly use in

power plants( 發電廠 ), factories( 工廠 ) and incinerators( 焚化爐 ) .

Scrubber is used to remove substances from the exhaust gas stream, or to neutralize those substances.

． ． Scrubber can be divided into dry and wet scrubber.Scrubber can be divided into dry and wet scrubber.

Scrubber

dry scrubber

wet scrubber

Dry and wet scrubber can be used separately , and also used together.

ScrubberScrubber(( 裝置滌氣器裝置滌氣器 ))

12

3

ScrubberScrubber(( 裝置滌氣器裝置滌氣器 ))

Electrostatic

precipitators

Electrostatic precipitation• removing fine particulates( 細小的微粒 ) from air

streams( 氣流 ), gases of combustion(( 燃燒 ) of fossil-fuel ( 化石燃料 )

Dirty gases pass through a strong electric field( 電場 ) dirty gases

particulates become charged( 帶電荷 ) charged

particulates are collected by opposite charge’s plants

What can the government do to reduce air pollution caused by the

mobile?

Vehicles:• sponsorsponsor to use LPG ( 液化石油氣 )• PromotePromote good driving habits• Set up monitoring stations(Set up monitoring stations( 空氣監測站空氣監測站 ))

What can the government do to reduce air pollution caused

by the stationary ?Factory:Factory:• Town planningTown planningEstate should be away from industry• Implement ordinancesImplement ordinancesEg: install scrubbers , filters and electrostatic precipitates

Power plantsPower plants(( 發電廠發電廠 ):):• Implement ordinancesImplement ordinancesuse natural gasnatural gas

Incinerators(Incinerators( 焚化爐焚化爐 ):):• Replaced by transfer stations

Factory

Refuse transfer station

Recent measures from the Policy Address 2007-2008

Regulation:． to limits the VOCVOC content of products． requiring power station to use natural gas

*note: voc causes smog

Mr Donald Tsang

The Present SituationVehicle Kilometres Travelled and Emission Trend

Emissions of nitrogen oxides and particulates from vehicles have been dropping despite an increase in kilometres travelled.

Comparison of New Vehicle Exhaust Emission Standards

Using petrol is better than using diesel !

Reference

• http://en.wikipedia.org/wiki/Catalytic_converter#Three-way_catalytic_converters

• http://www.air-quality.org.uk/25.php• http://www.air-quality.org.uk/25.php• From Wikipedia:• Catalytic converter• http://en.wikipedia.org/wiki/Catalytic_converter#

Three-way_catalytic_converters• Scrubber• http://en.wikipedia.org/wiki/Scrubber

Group members

• 5B Chung Yin Yung (1)• 5B Fung Yuen Yi (3)• 5B Kwan Yu Tung (4)• 5B Yeung Wing Sin (13)• 5B Kwan Man Ho (24)• 5B Kwok Ho Yin (26)