Automobile exhaust ozone layer

The waste gas contains 150 ~ 200 different compounds, and its main harmful components are unburned or incompletely burned CH, nitrogen oxides, CO, CO2, SO2, H2S, and trace lead and phosphorus pollution caused by aldehydes, phenols, peroxides, organic acids and gasoline containing lead and phosphorus. Among them, carbon monoxide, hydrocarbons, nitrogen oxides, lead compounds and particulate matter are the most harmful to people. Harmful gases diffuse into the air, causing air pollution.

Harm of automobile exhaust

1, the particulate matter in automobile exhaust contains a strong carcinogen benzo (a) pyrene. In general, 1 g particulate matter contains about 70 micrograms of benzo (a) pyrene, and 1 kg gasoline can produce 30 milligrams of benzo (a) pyrene. When the concentration of benzo (a) pyrene in the air reaches 0.0 1.2 μ g/m3, the number of people suffering from lung cancer will increase obviously.

2. The main pollutants emitted by automobile exhaust are carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NO X) and lead (Pb). Carbon monoxide: carbon monoxide has a strong affinity with hemoglobin in human red blood cells, which is dozens of times stronger than oxygen. Carboxyhemoglobin (COHb%) is generated after affinity, which weakens the function of blood to deliver oxygen to various tissues, causes dysfunction such as feeling, reflection, understanding and memory, and even endangers the blood circulation system, leading to life-threatening. Nitrogen oxides: Nitrogen oxides mainly refer to NO and NO2, which are harmful gases to human body, especially respiratory system. Exposure to air with NO2 concentration of 9.4mg/m2 (5PPm) for 10 minute can cause respiratory system disorder. Hydrocarbons: At present, its direct harm to human health is not clear. However, when HC and NOX are exposed to strong sunlight and ultraviolet rays in the atmospheric environment, they will produce complex photochemical reactions and produce a new pollutant-photochemical smog. Among the photochemical smog in London in June, 1952, the number of deaths in four days was about 4000 more than that in the same period of normal years, and the number of deaths over 45 years old was the most, about three times as high as usual; /kloc-the number of people under the age of 0 is about twice as high as usual. In the week before the incident, the number of people who died of bronchitis, coronary heart disease, tuberculosis and heart failure was 9.3 times, 2.4 times, 5.5 times and 2.8 times that of the week before the incident.

3. The harm degree of automobile exhaust mainly depends on the composition of gasoline. In the past, tetraethyl lead was usually used as an explosion-proof agent in automobile gasoline, and this gasoline-1 was used as leaded gasoline. Leaded gasoline makes the tail gas emitted by automobiles contain high concentration of lead, which is harmful to human health. In view of this, China began to use unleaded gasoline in 2000, and the corresponding tetraethyl lead was replaced by a series of new gasoline explosion-proof agents. In China, unleaded gasoline refers to gasoline with lead content below 0.01.3g/L. Therefore, unleaded gasoline is not gasoline with zero lead content, so automobile exhaust still contains a small amount of lead. Rural residents generally inhale about 1 microgram of lead from the air every day; The daily intake of lead by urban residents, especially those on both sides of the street, will greatly exceed this value.

At present, the new explosion-proof agents to replace tetraethyl lead in unleaded gasoline mainly include aromatic hydrocarbon, methyl tert-butyl ether (MTBE), triethyl butyl ether, tripentyl methyl ether, manganese carbonyl (MMT), alcohols and so on. , of which MTBE is the largest.

Automobile exhaust is not only harmful to people, but also toxic to plants. Secondary pollutants in waste gas, such as ozone and ethyl peroxynitrate, will cause necrotic spots and withered spots on plant leaves. Ethylene will affect the flowering and fruiting of plants. Automobile exhaust is more harmful to beets, spinach, tomatoes and tobacco. The reduction of crop production on both sides of the highway is obviously related to automobile exhaust pollution.

Automobile exhaust treatment method

1, three-way catalyst TWC (three-way catalyst), automobile exhaust purification catalyst.

The main harmful components of automobile exhaust are hydrocarbons (CnHm), carbon monoxide (CO) and nitrogen oxides (nitrogen oxides). These three substances are toxic to human body, among which CnHm and nitrogen oxides will also form photochemical smog under suitable conditions such as sunlight, which is more harmful. There are two main schemes to eliminate these harmful components in automobile exhaust: one is to improve the combustion mode of the engine to reduce the emission of harmful gases; The other is to use catalytic converter to purify harmful gases in tail gas. First of all, in 1975, the United States installed catalytic converters on new cars, and then Japan, Western Europe and other countries also adopted catalytic converters to meet the requirements of their own automobile emission regulations. There are two types of automotive catalytic converters. One is oxidation catalytic reactor, which makes CnHm and CO in the tail gas react with the residual oxygen in the tail gas to generate harmless H2O and CO2, thus achieving the purpose of purification.

Due to the mandatory emission standards of pollutants such as nitrogen oxides and the requirement of reducing fuel consumption, on the one hand, the air-fuel ratio should be controlled at 14.6 as much as possible, and on the other hand, methods such as controlling ignition timing and exhaust gas recirculation should be adopted to reduce nitrogen oxides in tail gas. However, the disadvantage of these methods is that they often increase CnHm and CO in tail gas. In order to solve this problem, three-way catalyst (TWC) appeared. The characteristic of this catalyst is that it can simultaneously purify carbon monoxide (CO), hydrocarbons (CnHm) and nitrogen oxides (nitrogen oxides) in automobile exhaust with one catalyst. However, in order to exert its catalytic performance, the air-fuel ratio must always be controlled at around 14.6 0. 1. This catalytic purifier has high purification rate, but it needs oxygen sensor, multi-point fuel injection and electronic ignition. This catalytic purifier takes O2 and nitrogen oxides in the tail gas as oxidants and CO, CnHm (represented by CH2) and H2 as reductants, and the following reactions can occur near the theoretical air-fuel ratio:

2CO+O2=2CO2

2CO+2NO=N2+2CO2

CH2+3nNO=nN2+nCO2+nH2O

2NO+2H2=N2+2H2O

At present, most of the three-way catalysts used are based on porous ceramics, and then the so-called coating is attached, and finally the active components are adsorbed by impregnation. The active components of the catalyst are mainly precious metals, such as platinum (Pt), palladium (Pd) and rhodium (Rh). Because precious metal resources are scarce and expensive, scientists all over the world are committed to the research of rare earth/palladium three-way catalyst which is economically and technically feasible. It is expected that the catalyst has a good application prospect.

Three-way catalytic purifier has the advantages of good purification rate and fuel economy, but the main problem is high cost. Because there is a lot of residual oxygen in the gas emitted by diesel engine, the control of oxygen sensor is not sensitive, so the three-way catalytic purifier is generally not used in diesel engine, but only suitable for gasoline engine.

2. Develop new energy vehicles.

The fuel used in cars is gasoline and diesel, both of which are extracted from petroleum. However, petroleum, a fossil fuel, is non-renewable. Use less if you use a little, and you will run out one day. According to scientists' prediction, the global proven oil reserves will be exhausted around 2020. Therefore, cars will face the danger of starvation, and human beings will face the challenge of energy.

On the other hand, petroleum itself is a valuable chemical raw material, which can be used to make plastics, synthetic rubber and synthetic fibers. Burning petroleum as fuel is not only a pity, but also pollutes the environment on which human beings depend.

The only feasible way to solve this problem is to speed up the development of new energy. Solar energy is the best of these newly developed energy sources.

① Solar car

Converting sunlight into electric energy is an important way to utilize solar energy. As early as 1950s, people made the first photovoltaic cell. The photovoltaic cell is installed on the car, and it is used to continuously convert sunlight into electric energy to start the car. This kind of car is a new solar car.

You see, there are many honeycomb devices on the solar car, that is, solar panels. The iron wings we usually see on satellites are also a kind of solar panels for satellite electricity.

According to the different semiconductor materials used, solar cells are usually divided into silicon cells, cadmium sulfide cells, gallium arsenide cells and so on. Silicon solar cells are the most commonly used.

Silicon solar cells are round, semi-circular and rectangular. There are small silicon chips as thin as paper on the battery. By uniformly doping some boron on one side of the silicon wafer and some phosphorus on the other side, and installing electrodes on both sides of the silicon wafer, light energy can be converted into electric energy.

On the top of Libbit Blick II solar car, there is an arc-shaped solar panel with many solar cells arranged neatly on it. Under the irradiation of sunlight, these solar cells generate electromotive force between electrodes, and then through the wires connecting the two electrodes, there will be current output.

Silicon solar cells can generally convert 10% ~ 15% of solar energy into electric energy. It is not only convenient to use and durable, but also clean and does not pollute the environment. It is an ideal power supply. Only the proportion of photoelectric conversion is smaller. In recent years, the United States has developed high-performance solar cells with a photoelectric conversion rate of 35%. The photoelectric conversion rate of solar cells made by laser technology in Australia is 24.2%, and the cost is equivalent to that of diesel power generation. All these have opened up broad prospects for the application of photovoltaic cells in automobiles.

Solar cars not only save energy and eliminate the pollution of fuel gas, but also make little noise even when driving at high speed. Therefore, solar cars have aroused great interest and will develop rapidly in the future.

② Hydrogen-powered vehicles

It is predicted that the global oil resources will be exhausted in 100 at the current exploitation rate! Facing the increasingly urgent dual pressures of resources and environment, it has become a trend that "hydrogen energy" replaces "ore energy". Hydrogen is a storable energy source. It is a typical natural material recycling process that uses water to directly generate hydrogen, and after combustion, hydrogen combines with oxygen to generate water. Many prototypes have been tested on the road, and General Motors even declared that "by 20 10 years ago, fuel cell vehicles that people can afford will be driven in the streets."

Noisy emission

Hydrogen-oxygen fuel cell is a power generation device that generates water and releases electric energy through the electrochemical reaction of hydrogen and oxygen. This reaction process does not involve combustion, and the energy conversion rate is as high as 60%-80%. The actual use efficiency is 2-3 times that of ordinary internal combustion engines, and it also has the advantages of extremely low noise and real zero emission. Using this device to replace the current car driven by internal combustion engine is a "fuel cell car".

Mercedes-Benz Company proved for the first time that fuel cells can drive cars-1994, Mercedes-Benz developed the world's first hydrogen ion power generation fuel cell car, with a top speed of 100 km and a driving range of 130 km each time. And several prototypes of GM are already showing the bright future of future cars.

When will the "hydrogen age" come?

The high cost of hydrogen production and fuel cell application is the technical key to restrict the industrialization of hydrogen energy. At present, the goal of scientific research is that the cost of hydrogen production can be comparable to that of gasoline; Second, the cost of fuel cells is comparable to that of internal combustion engines. According to experts, the cost of fuel cell engines announced by the United States in 2002 was $65,438+0,000 per kilowatt. In 2003, it was reduced to 5,000 to 6,000 dollars, and this year it can be reduced to less than 4,000 dollars. When the price of fuel cell engine drops to 100 USD and the cost of hydrogen production falls below 2 USD, the "hydrogen economy era" can really come. According to the global consumption of 2 tons of gasoline for 1 0.50 billion vehicles and 1 year, using hydrogen energy for1year can save 300 million tons of gasoline, which is equivalent to the annual output of three Kuwait.

China urgently needs "hydrogen economy"

At present, the United States and Iceland have drawn up a timetable for the transition to a "hydrogen economy", the United States, Japan and the European Union have begun to implement hydrogen energy plans, India has drawn up a road map for the development of hydrogen energy, and Brazil has made remarkable achievements in the utilization of hydrogen energy. Compared with developed countries, China faces challenges in the world competition of developing "hydrogen economy", and there are also more rare opportunities.

③ Electric vehicles

The basic characteristics of electric vehicles are that they can carry their own electric energy, run along the general roads like ordinary diesel locomotives, and their power, economy, safety and reliability reach or approach those of ordinary diesel locomotives, and their driving range meets the general operating requirements. At the same time, electric vehicles use low-voltage electricity, which has the advantages of no emission pollution, low noise, easy maintenance and energy saving, and is considered as an ideal means of transportation in the future. The technical contents of electric vehicles include:

● Power battery technology: nickel-hydrogen battery, nickel-cadmium battery, lead-acid battery, sodium-sulfur battery, lithium-ion battery, fuel battery, etc. , should have high specific power and specific energy, can meet the requirements of power and driving range: short charging time, more charging cycles, so as to facilitate use and ensure service life.

● Motor technology: There are four main types of motors: DC motor, permanent magnet motor, switched reluctance motor and AC induction motor. Light weight, high efficiency and good reliability are required.

● Control and integration technology of drive system: The control system often adopts single chip microcomputer and power device, and the power device mainly adopts IGBT.

● Battery monitoring and management system technology

● Charging system technology

● Vehicle Layout and Matching Technology of Electric Vehicles

Second, the current situation and development trend at home and abroad

Since 1990s, foreign countries have been paying attention to the research on key technologies of batteries. The three major American automobile companies have invested $2.6 billion in cooperative research, and the USABC project jointly carried out by American battery manufacturers has also targeted the batteries for electric vehicles. At present, the status quo of battery technology is far from the practical requirements of electric vehicles, which makes electric vehicles unable to compare with conventional vehicles in terms of power performance, driving range, manufacturing cost and reliability. The prospect of electric vehicles basically depends on the breakthrough of battery technology. In recent years, Ni-MH, Li, fuel and other batteries have been paid more attention, and a lot of money has been invested in research. The improvement of traditional batteries such as lead acid and Ni-Cd is also under way.

The State Science and Technology Commission and the Planning Commission organized key research projects on electric vehicles during the Eighth Five-Year Plan and the Ninth Five-Year Plan, and recently included the electric vehicle project in the Tenth Five-Year Plan. Domestic large-scale automobile enterprises, universities and scientific research institutes also take a positive attitude towards the research of electric vehicles, and have carried out several rounds of trial production by modifying electric vehicles, striving to realize the industrialization of electric vehicles at the end of the Tenth Five-Year Plan.

With the development of economy, the number of families owning private cars is also increasing, which leads to increasingly serious air pollution. In order to solve this problem, I wonder if we can use what we have learned to solve this increasingly serious problem!

The solution (1) uses alkaline substances (such as sodium hydroxide and potassium hydroxide). ) to absorb nitrogen oxides emitted by cars.

(2) Ammonia is used to absorb nitrogen oxides emitted by automobiles.

Draw a conclusion according to the equation

( 1)2NaOH+NO2=NaNO3+H2O

(2)8NH3H2O+6NO2=7N2+20H2O

Through the treatment of automobile exhaust, the emission of harmful particles can be reduced. Nitrogen oxides and particulate matter emitted by automobiles can cause various respiratory diseases, such as asthma and emphysema.

I don't know how to know that the ammonia is used up.