From a global perspective, another major factor of air pollution is automobile exhaust. Automobile exhaust contains carbon monoxide and oxygen.
Nitrogen and other solid particles that have adverse effects on human body, especially leaded gasoline, are more harmful to human body.
It's huge. Lead is in a particulate state in the exhaust gas and diffuses with the wind. Rural residents usually inhale lead from the air.
The sky is about one microgram; Urban residents, especially those on both sides of the street, will greatly exceed rural residents. After tin enters the human body, it mainly
It should be distributed in liver, kidney, spleen, gallbladder and brain, with the highest concentration in liver and kidney. After a few weeks, lead was transferred from the above tissues to the bones.
Skeleton, deposited as insoluble lead phosphate. About 90% ~ 95% of lead in human body is accumulated in bones, and only a small amount of lead exists.
In the liver, spleen and other organs. Lead in bone is generally stable, when food is calcium deficient or infected, injured, drinking alcohol or taking acid.
When alkaline drugs destroy the acid-base balance, lead will be transferred from bones to blood, causing lead poisoning symptoms. Symptoms of lead poisoning
It has a wide range of manifestations, such as dizziness, headache, insomnia, dreaminess, hypomnesis, fatigue, loss of appetite, fullness and warmth in the upper abdomen.
Gas, nausea, diarrhea, constipation, anemia, peripheral neuritis, etc. Severe poisoning patients have obvious liver damage and yellow color will appear.
Symptoms such as jaundice, hepatomegaly and abnormal liver function. 1943, in Los Angeles, California, there are 2.5 million cars.
Cars burn 1 100 tons of gasoline every day. Hydrocarbons produced by gasoline combustion are chemically irradiated by ultraviolet rays from the sun.
Reaction, the formation of light blue smoke, so that most people in this city envy, headache. Later, people called this pollution photochemistry.
It's smoking There were two photochemical smog incidents in Los Angeles at 1955 and 1970. The former has more than 400 people suffering from five senses poisoning.
Suction failed and died, which made three-quarters of the people in the city sick. This is called "the eight public hazards in the world" in history.
The photochemical smog event in Los Angeles, one of the "top ten environmental hazards in the 20th century". It is these events that make people deeply realize.
The harm of automobile exhaust is analyzed.
In order to improve urban air quality, the United States has made strict plans to reduce automobile pollution. 1996, the EU has also laid down the basis.
It is said that the automobile exhaust emission plan is stricter than that in the United States. In the EU plan, the standards for improving the quality of gasoline and diesel are put forward.
It is required to eliminate leaded gasoline before 2000 and adopt special fuels in heavily polluted areas such as Athens and London. At the same time, we must
All new models must be technically reformed to purify automobile exhaust. According to the survey, 0/0% of children in Britain/KLOC are 6 years old.
Lead poisoning. Lead poisoning in children will reduce IQ, and there will be disruptive and negligent behavior.
In order to improve air quality, many cities in China prohibit polluting enterprises from entering urban areas; Carry out technical transformation on the original enterprises,
Reduce the emission of waste gas and smoke and provide central heating. Reduce the smoke and dust emission of heating stoves, improve the quality of diesel oil and gasoline, and reduce
Exercise content, actively transition to unleaded gasoline, install car purifier, and so on.
2004/05/23 12:35
In today's modern civilization, cars have become an indispensable means of transportation for human beings. Since the first car on 1886
Since its birth, the automobile has brought great convenience to people's life and work, and has also developed into a modern material civilization.
One of the pillars. However, we should also see that with the rapid development of the automobile industry, the output and possession of automobiles are increasing.
At the same time, cars also bring air pollution, that is, automobile exhaust pollution.
1943, in Los Angeles, California, 2.5 million cars burned 1 100 tons of gasoline every day. petrol
The hydrocarbons produced after combustion react chemically under the irradiation of ultraviolet rays from the sun, forming light blue smoke, which makes the city
Most citizens have envy and headaches. Later, people called this pollution photochemical smog. 1955 and 1970 Los Angeles
Two photochemical smog incidents occurred, the former caused more than 400 people to die of five senses poisoning and respiratory failure, and the latter caused four points in the city.
Two thirds of people are sick. This is one of the "eight public hazards in the world" and "ten environmental hazards in the 20th century" in history.
Photochemical smog incident in Los Angeles. It is these events that make people deeply realize the harmfulness of automobile exhaust.
Gasoline is mainly composed of carbon and hydrogen. When gasoline burns normally, it will produce carbon dioxide, water vapor and excessive oxygen. but
Because fuel contains other impurities and additives, and fuel often cannot be completely burned, some harmful substances are often discharged. study
The results show that the composition of automobile exhaust is very complex, with more than 100, and its main pollutants include carbon monoxide, hydrocarbons and
Nitrogen oxides. Carbon monoxide will hinder human blood absorption and oxygen transmission and affect human hematopoietic function, which may be induced at any time.
Angina pectoris, coronary heart disease and other diseases. Hydrocarbons can form highly toxic photochemical smog, which is harmful to human body and produces
Carcinogenic substance. White smoke is harmful to livestock, fruits, rubber products and buildings. Nitrogen oxides make people
Poison is stronger than carbon monoxide, which damages people's glasses and lungs and forms photochemical smog, which is the main substance to produce acid rain.
Turn plants from green to brown until they die on a large scale.
There are three main ways to control automobile exhaust. First, the most fundamental and last way is to change the power of the car. such as
Develop electric vehicles and alternative fuel vehicles. In this way, the car will not produce any or only a little pollution gas. Second,
Improve the quality of existing automobile power plant and fuel. Adopt a well-designed engine, improve the combustion chamber structure and adopt new materials.
Material consumption and improving fuel quality can reduce automobile exhaust pollution, but they cannot achieve "zero emission". Third, it is also the present.
It is suitable for the widely used purification technology of a large number of in-use cars and new cars. It is to use some advanced external purification technologies for automobile production.
It is impossible to achieve "zero pollution" by purifying the original waste gas and reducing pollution. The purification technology outside the car is inside the car.
Various purification devices are installed in the exhaust system to reduce pollutants in the exhaust by physical and chemical methods. Can be divided into catalysis.
Device, thermal reactor and filter collector, etc. The former is mostly used for gasoline locomotives, while the latter is mostly used for diesel locomotives.
Automobile exhaust
In large and medium-sized cities in China, automobile exhaust emission has become the main air pollution source. Some data show that the total number of cars in Shanghai
The amount is only equivalent to112 in Tokyo, Japan, but the total amount of CO, HC and nitrogen oxides mainly emitted by automobiles in the air is basically the same.
At present, there are more than130,000 vehicles in use in China. But with the rapid development of economy and the increase of social demand, in the future, 654.38+00.
From 65,438 cars to 2005, the number of cars in China will increase at an average annual rate of 9%. Therefore, it is urgent to reduce automobile exhaust emissions.
Make love.
Automobile exhaust purification catalyst is the most effective means to control automobile emissions and reduce automobile pollution. Mainly made of precious metals.
Automobile exhaust purification catalyst and rare earth catalyst. Platinum and palladium are mainly used as precious metal catalysts and have activity.
High, long service life and good purification effect, so it is very practical. However, these precious metals are expensive and difficult to be widely used.
Promotion.
Rare earth catalysts used to purify automobile exhaust are catalysts made of rare earth, alkaline earth metals and some base metals. It is also useful and rare.
A small amount of catalyst made of precious metals is added to the soil. Its characteristics are low price, good thermal stability, high activity and long service life. because
This is very popular in the field of automobile exhaust purification.
Rare earth used in rare earth automobile exhaust purification catalyst is mainly a mixture of cerium oxide, praseodymium oxide and lanthanum oxide.
Among them, cerium oxide is the key component. Due to the redox characteristics of cerium oxide, the composition of exhaust gas can be effectively controlled, and it can also
Oxygen is supplied in the original atmosphere or consumed in the oxidizing atmosphere. CeO2 also plays a stabilizing role in precious metal atmosphere to maintain its catalytic effect.
The catalyst has high catalytic activity.
Because developed countries such as Europe, America and Japan have earlier and stricter control over automobile exhaust emissions, they are used.
Automotive exhaust purification catalysts are widely used. At present, it is mainly a three-way catalyst. The catalyst not only oxidizes HC and CO to form
Oxidizing agents for H2O and carbon dioxide, and reducing agents for reducing nitrogen oxides into N2. This can play a very good purification role. such
Rare earth elements are indispensable elements of three-way catalyst. According to some reports, the demand of the world automobile exhaust purification catalyst market is
The annual growth rate of 7% is increasing. It can be seen that the amount of rare earth in automobile exhaust purification catalyst is considerable. 1995
The consumption of rare earth in the field of automobile exhaust purification catalysts in the United States reached 1 1 000 tons (calculated by oxides), accounting for 1 995 of the total rare earth in the United States.
44% of the consumption, 1996, Japanese cerium oxide used in the catalyst field also reached 1500 tons, while China's application in this field.
It can be said that it is a blank.