There are two types of "systems" running in a catalytic converter, "lean" and "rich. On the contrary, when the system is running "rich," there is more fuel than needed, and the reactions favor the reduction of nitrogen oxides into elemental nitrogen and oxygen at the expense of the two oxidation reactions.
Note: converters can store "extra" oxygen in the exhaust stream for later use. This storage usually occurs when the system is running lean; the gas is released when there is not enough oxygen in the exhaust stream.
The released oxygen compensates for the lack of oxygen derived from NO x reduction, or when there is hard acceleration and the air-to-fuel ratio system becomes rich faster than the catalytic converter can adapt to it.
Without the redox process to filter and convert the nitrogen oxides, carbon monoxides, and hydrocarbons, the air quality especially in large cities becomes harmful to the human being. Nitrogen oxides: These compounds are of the same family as nitrogen dioxide, nitric acid, nitrous oxide, nitrates, and nitric oxide. When NO x is released into the air, it reacts, stimulated by sunlight, with organic compounds in the air; the result is smog. Smog is a pollutant and has adverse effects on children's lungs.
NO x reacting with sulfur dioxide produces acid rain, which is highly destructive to everything it lands on. Acid rain corrodes cars, plants, buildings, national monuments and pollutes lakes and streams to an acidity unsuitable for fish. NO x can also bind with ozone to create biological mutations such as smog , and reduce the transmission of light.
Carbon monoxide: This is a harmful variant of a naturally occurring gas, CO 2. Odorless and colorless, this gas does not have many useful functions in everyday processes. Hydrocarbons: Inhaling hydrocarbons from gasoline, household cleaners, propellants, kerosene and other fuels can be fatal to children. Further complications include central nervous system impairments and cardiovascular problems. The catalytic converter is a sensitive device with precious metals coating the inside.
Without these metals, the redox reactions cannot occur. There are several substances and chemicals that inhibit the catalytic converter. These contaminants prevent the catalytic converter from functioning properly. However, this process could be reversed by running the engine at a high temperature to increase the hot exhaust flow through the converter, melting or liquefying some of the contaminants and removing them from the exhaust pipe.
This process does not work if the metal is coated with lead, because lead has a high boiling point. If the lead poisoning is severe enough, the whole converter is rendered useless and must be replaced. Recall that thermodynamics predicts whether or not a reaction or process is spontaneous under certain conditions, but not the rate of the process.
The redox reactions below occur slowly without a catalyst; even if the processes are thermodynamically favorable, they cannot occur without proper energy. Catalytic converters need to work at high temperatures of up to degrees to maximise their efficiency. There are various types of catalytic converter.
Diesel cars typically have special catalytic converters to cope with the specific emissions from compression ignition diesel engines. These Diesel Oxidation Catalyst units are routinely paired with additional exhaust treatment technologies such as exhaust gas recirculation, Diesel Particulate Filters to trap soot and Selective Catalytic Reduction which uses injections of AdBlue urea solution to remove NOx.
Reports suggest that the growth could be attributed to supply chain issues which have made it harder for dealers to secure replacement catalytic converters through official channels, creating a black market. Historically, however, the greatest driver of thefts has been the overseas markets for the precious metals inside the units. Catalytic converters stolen in the UK are often illegally transported abroad and the metals recycled.
While thefts of catalytic converters are still rare, there are some simple steps you can take to protect your vehicle Catalytic converters have been around since the 19th century when metal cylinders containing filters coated in platinum, Iridium and palladium were fitted to early French motor cars in an attempt to clean up the smoke coming out of their exhausts.
The easiest way to preheat the converter is to use electric resistance heaters. Unfortunately, the volt electrical systems on most cars don't provide enough energy or power to heat the catalytic converter fast enough. Most people would not wait several minutes for the catalytic converter to heat up before starting their car.
Hybrid cars that have big, high-voltage battery packs can provide enough power to heat up the catalytic converter very quickly. Catalytic converters in diesel engines do not work as well in reducing NOx.
One reason is that diesel engines run cooler than standard engines, and the converters work better as they heat up. Some of the leading environmental auto experts have come up with a new system that helps to combat this. They inject a urea solution in the exhaust pipe, before it gets to the converter, to evaporate and mix with the exhaust and create a chemical reaction that will reduce NOx.
Urea, also known as carbamide , is an organic compound made of carbon, nitrogen, oxygen and hydrogen. It's found in the urine of mammals and amphibians. Urea reacts with NOx to produce nitrogen and water vapor, disposing more than 90 percent of the nitrogen oxides in exhaust gases [source: Innovations Report ].
A standard catalytic converter contains several hundred dollars worth of platinum, palladium and rhodium. The ground clearance on trucks and SUVs makes for easy access to the converters, so all a thief needs is a reciprocating saw and about 60 seconds. This trend has police on the lookout in many parts of the country where this kind of theft has been a problem. Police caution SUV and truck drivers to park in busy, well-lit areas.
Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Under the Hood. How Catalytic Converters Work. A large pile of platinum lined catalytic converters. See more green living pictures. James L. Pollutants Produced by a Car Engine " ". Nitrogen gas N2 - Air is percent nitrogen gas, and most of this passes right through the car engine.
Carbon dioxide CO2 - This is one product of combustion. The carbon in the fuel bonds with the oxygen in the air. Water vapor H2O - This is another product of combustion. The hydrogen in the fuel bonds with the oxygen in the air.
Carbon monoxide CO is a poisonous gas that is colorless and odorless. Hydrocarbons or volatile organic compounds VOCs are a major component of smog produced mostly from evaporated, unburned.
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