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Macurco Gas Detection Products
Automotive
Emissions in the
Parking Garage
Training
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Automotive Emissions Training
Outline
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History
How Does A Catalytic Converter
Work?
Catalytic Converters Reduce
Pollution
Two-Way
Three-Way
Diesel Engines
Catalytic Converter Damage
Emissions Testing
Emissions in Parking Garages
History of Automotive Emissions
In the 1940s, residents of Los Angeles complained of the yellowish haze
that hung over the city. Called "smog" because of its appearance as smoke
and fog, scientists attributed auto emissions to the poor air quality in many
urban areas.
• Because of its high concentration of automobiles in
post-World War II America, Los Angeles has figured
significantly in the history of auto emissions.
• In 1959, the Los Angeles County Health
Department received resident complaints of eye
irritation, primarily due to auto emissions, on 187
days of the year. By 1962, the number had climbed
to 212 days.
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History of Automotive Emissions
A typical car produced in 1963, before any attempt was made to
control auto emissions, discharged 520 pounds of hydrocarbons,
1,700 pounds of carbon monoxide and 90 pounds of nitrogen oxide
for every 10,000 miles of operation.
• According to a report by the University of MichiganDearborn, in 1966, nearly 60 percent of air
pollution was a direct result of auto emissions.
• The first federal Clean Air Act of 1963 brought
American air quality to the public's attention and
spurred automakers to begin making attempts at
controlling the amount of exhaust their vehicles
emitted.
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History of the Catalytic Converter
The catalytic converter was invented by Eugene Houdry, a French
mechanical engineer and expert in catalytic oil refining who lived in the U.S.
and in the mid 1950s he began research to develop catalytic converters for
gasoline engines used on cars.
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Widespread adoption of catalytic converters did not occur until more stringent emission
regulations forced the removal of the “lead” from gasoline. The lead was a ‘poison’ that
would inactivate the converter by forming a coating on the catalyst’s surface, effectively
disabling it.
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Catalytic converters were further developed by a series of engineers creating the first
production catalytic converter in 1973.
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A catalytic combustor for gas turbines was developed in the early 1970s, allowing
combustion without significant formation of nitrogen oxides and carbon monoxide.
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History of the Catalytic Converter
In 1971, the U.S. government legalized catalytic converters in order to
reduce four kinds of vehicles emissions: hydrocarbon, nitrogen oxides
(NOx), carbon monoxide (CO) and carbon dioxide (CO2).
• In 1990, America's Clean Air Act further empowered
the Office of Transportation and Air Quality, a branch of
the Environmental Protection Agency (EPA) to
enforce U.S. federal standards.
• Catalytic converters that do not meet EPA standards
are against the law
• The average lifespan of a catalytic converter is 7-10
years depending on the elements and condition of the
vehicle
http://www.ehow.com/list_7148807_catalytic-converter-federal-laws.html
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How Does A Catalytic Converter Work?
As the exhaust flows through the substrate inside the converter housing, the
catalytic reaction takes place. As the pollutants like NO2 (nitrogen oxide), HC
(hydro carbon) and CO (carbon monoxide) pass through the substrate they are
converted into less harmful compounds such as CO2 (carbon dioxide), H2O
(water) and N2 (nitrogen). This conversion starts at temperatures around 2500
Celsius.
https://www.catalyticconvertersonline.com/x-how-a-catalytic-converter-works-1
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How Does A Catalytic Converter Work?
A catalyst is a substance that causes or accelerates a chemical reaction
without itself being affected. Catalysts participate in the reactions, but are
neither reactants nor products of the reaction they catalyze.
• There are two different types of catalysts in a catalytic converter. A reduction
catalyst and an oxidation catalyst.
• Both consist of a ceramic structure coated with a metal catalyst, usually
platinum, rhodium and/or palladium. This creates a structure that exposes
the maximum surface area of catalyst to the exhaust stream, whilst minimizing
the amount of catalyst required.
• Some of the new converters have started to use gold mixed with the traditional
catalysts which could increase oxidation.
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Catalytic Converters Reduce Pollution
Most modern cars are equipped with three-way catalytic converters. This
refers to the three regulated emissions it helps to reduce.
• The reduction catalyst is the first stage of the catalytic converter. It uses
platinum and rhodium to help reduce the NOx emissions.
• When an NO or NO2 molecule contacts the catalyst, the catalyst rips the
nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the
form of O2. The nitrogen atoms bond with other nitrogen atoms that are also
stuck to the catalyst, forming N2. For example:
2NO => N2 + O2
or
2NO2 => N2 + 2O2
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Catalytic Converters Reduce Pollution
Ceramic honeycomb catalyst structure.
• The oxidation catalyst is the second stage of the catalytic
converter. It reduces the unburned hydrocarbons and carbon
monoxide by burning (oxidizing) them over a platinum and
palladium catalyst.
• This catalyst aids the reaction of the CO and hydrocarbons
with the remaining oxygen in the exhaust gas. For example:
2CO + O2 => 2CO2
• There are two main types of structures used in catalytic
converters — honeycomb and ceramic beads. Most cars
today use a honeycomb structure.
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Catalytic Converter Types
http://fansofautomobile.blogspot.com
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Two-way Catalytic Converter
A two-way (or “oxidation”) catalytic converter has two
simultaneous tasks:
A. Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2
B. Oxidation of hydrocarbons (unburned and partially burned fuel) to carbon dioxide
and water: CxH2x+2 + [(3x+1)/2] O2 → xCO2 + (x+1) H2O (a combustion reaction)
• This type of catalytic converter is widely used on diesel engines to reduce
hydrocarbon and carbon monoxide emissions.
• They were also used on gasoline engines in American and Canadian market
automobiles until 1981.
• Because of their inability to control oxides of nitrogen, they were
superseded by three-way converters.
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Three-way Catalytic Converter
A three-way catalytic converter has three simultaneous tasks:
A.
B.
C.
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: CxH2x+2 +
[(3x+1)/2]O2 → xCO2 + (x+1)H2O.
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These three reactions occur most efficiently when the catalytic converter
receives exhaust from an engine running slightly above the stoichiometric
point (14.6 to 14.8 parts air to 1 part fuel, by weight, for gasoline).
Since 1981, “three-way” (oxidation-reduction) catalytic converters have been
used in vehicle emission control systems in the US and Canada
The catalysts are typically contained in a common housing, however in some
instances they may be housed separately.
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Three-way Catalytic Converter
In general, engines fitted with 3-way catalytic converters are
equipped with a computerized closed-loop feedback fuel
injection system using one or more oxygen sensors.
• Closed-loop control systems are necessary because of the conflicting
requirements for effective NOx reduction and HC oxidation.
• The control system must prevent the NOx reduction catalyst from
becoming fully oxidized, yet replenish the oxygen storage material to
maintain its function as an oxidation catalyst.
• Three-way catalysts are effective when the engine is operated within a
narrow band of air-fuel ratios near stoichiometry, such that the exhaust gas
oscillates between rich (excess fuel) and lean (excess oxygen) conditions.
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Three-way Catalytic Converter
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Three-way Catalytic Converter
Efficiency falls rapidly when the engine is operated outside of that band of
air-fuel ratios. Under lean engine operation, there is excess oxygen and the
reduction of NOx is not favored. Under rich conditions, the excess fuel
consumes all of the available oxygen prior to the catalyst, so only stored
oxygen is free the oxidation function.
• Three-way catalytic converters can store oxygen from the
exhaust gas stream, usually when the air-fuel ratio goes lean.
• When insufficient oxygen is available from the exhaust stream,
the stored oxygen is released and consumed.
• Vehicles emit most of their pollution during the first five
minutes of engine operation before the catalytic converter
has warmed up sufficiently.
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Diesel Engine Catalytic Converter
For compression-ignition (i.e., diesel engines), the most commonly used
catalytic converter is the Diesel Oxidation Catalyst (DOC). This catalyst uses
O2 (oxygen) in the exhaust gas stream to convert CO (carbon monoxide) to
CO2 (carbon dioxide) and HC (hydrocarbons) to H2O (water) and CO2.
• These converters often operate at 90 percent efficiency, virtually eliminating
diesel odor and helping to reduce visible particulates (soot).
• These catalysts are not active for NOx reduction because any reductant
present would react first with the high concentration of O2 in diesel exhaust
gas.
• Reduction in NOx emissions from compression-ignition engines has previously
been addressed by the addition of exhaust gas to incoming air charge, known
as exhaust gas recirculation (EGR).
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Diesel Engine Catalytic Converter
In 2010, most light-duty diesel manufacturers in the U.S. added catalytic
systems to their vehicles to meet new federal emissions requirements.
• There are two techniques that have been developed for the catalytic reduction
of NOx emissions under lean exhaust conditions – selective catalytic reduction
(SCR) and the lean NOx trap or NOx adsorber.
• Instead of precious metal-containing NOx adsorbers, most manufacturers
selected base-metal SCR systems that use a reagent such as ammonia to
reduce the NOx into nitrogen.
• Ammonia is supplied to the catalyst system by the injection of urea into the
exhaust, which then undergoes thermal decomposition and hydrolysis into
ammonia. http://catalyticconverters.com
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Catalytic Converter Damage
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Catalytic Converter Damage
Catalyst poisoning occurs when the catalytic converter is exposed to
exhaust containing substances that coat the working surfaces,
encapsulating the catalyst so that it cannot contact and treat the exhaust.
• The most-notable contaminant is lead, so vehicles equipped with catalytic
converters can be run only on unleaded fuels.
• Another poison is silicone, which can enter the exhaust stream if the engine
has a leak that allows coolant into the combustion chamber.
• Catalyst poisoning can sometimes be reversed by running the engine under
a very heavy load for an extended period of time.
• Abnormally high levels of unburned fuel reaching the converter will significantly
elevate its temperature, bringing the risk of a meltdown of the substrate and
resultant catalytic deactivation and exhaust restriction.
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Emissions Testing
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Emissions Testing
Arizona
California
Colorado
Connecticut
Delaware
Georgia
Idaho
Illinois
Indiana
Maine
Maryland
Massachusetts
Missouri
Nevada
New Hampshire
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New Jersey
New Mexico
New York
North Carolina
Ohio
Oregon
Pennsylvania
Rhode Island
Tennessee
Texas
Utah
Vermont
Virginia
Washington
Wisconsin
Alabama
Alaska
Arkansas
Florida
Hawaii
Iowa
Kansas
Kentucky
Louisiana
Michigan
Minnesota
Mississippi
Montana
Nebraska
North Dakota
Oklahoma
South Carolina
South Dakota
West Virginia
Wyoming
There are currently 30 states
that require some form of
vehicle emissions testing.
Emissions Testing
The first emissions testing was done in California in 1966 and now there are
currently 30 states that require some form of vehicle emissions testing.
• Emissions testing is done to ensure that air pollution emissions from vehicles
are at minimal levels.
• Any vehicles that are found to emit too many pollutants will be required to
have the issue repaired on their vehicle.
• Each state has different emissions standards, costs, testing policies,
guidelines, fees, penalties, testing locations, retesting directions, procedures,
repair assistance for low income earners, and steps to dispute a test result.
• Depending on the state, some states do not require any emissions testing to
be completed.
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Emissions Testing
Other states require emissions testing only within certain counties or zip
codes, and some states require all vehicles to have their emissions tested on a
set basis.
• Some states require emissions testing to be done only within certain inspection
areas in the state while other states offer statewide emissions testing locations.
• Most states have standard emissions fees but there are some states such as
California that allow the emissions inspections service stations to set their own
price.
• Every state has a department that handles all emissions inquiries, complaints,
questions, and policies, but depending on the state it can be its own department,
a department of the DMV, the DMV itself, the Department of Consumer Affairs, or
something else.
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Emissions In Parking Garages
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Emissions In Parking Garages
If cars are required to have catalytic converters, why is there still a need for
gas detection in enclosed parking garages?
• Some states require emissions testing to be done and some do not
• Older cars do not use catalytic converters
• The older Two-Way converters are unable to control oxides of nitrogen and this
type of catalytic converter is still widely used on diesel engines.
• A catalytic converter’s efficiency falls rapidly when the engine is operated
outside of the narrow band of air-fuel ratios.
• Vehicles emit most of their pollution during the first five minutes of engine
operation before the catalytic converter has warmed up sufficiently.
• Diesel Oxidation Catalyst (DOC) are not active for NOx reduction
• Catalytic converters can be poisoned, damaged and just worn out.
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