application research progress in environmental protection, environmental protection catalysts is the definition of environmental catalyst refers to with direct or indirect methods dealing with poisonous and harmful substances, make it harmless or reduction, the catalyst used to protect and improve the surrounding environment.
The category of environmental catalyst in a broad sense, all catalyst can be considered to be beneficial to environmental protection, including don't or do not produce harmful by-products of catalytic synthesis process;
In a narrow sense, is to the greenhouse effect, ozone depletion, acid rain range expansion, and water pollution, etc. The improvement of the catalyst species involved.
Environmental catalysts are divided into direct and indirect two kinds.
For example, get rid of nitrogen oxides from exhaust (
Using catalyst belongs to the direct;
And used to produce with inhibition of NOX in the process of combustion catalysts, indirect.
2, environmental catalyst application research progress of 2.
1 lean burn automobile catalyst diesel engine under the condition of lean burn operation, gasoline engine air-fuel ratio (
The ratio of air and fuel)
More than now, even higher.
At this point, the dynamic performance of engine can be greatly improved, reduces the emission of CO, hydrocarbons, CO2 and NOx emissions, however, is greatly increased.
For current popular three-way precious metal catalyst, such high air-fuel ratio is beyond normal operating range, therefore, cannot effectively improve the NOx reduction.
Therefore should be developed under the condition of lean burn and can improve the NOx conversion rate of new automotive catalyst, the catalytic reduction of NOx in lean combustion conditions has aroused researchers' interest.
Once this catalyst research, success will be diesel engine and the inferior type of gasoline engine is widely used in a car.
2 the best way to research on flue gas desulfurization of flue gas desulfurization is the selective catalytic reduction of SO2 to elemental sulfur.
This method can not only eliminate the pollution of SO2 in flue gas, and recycling the product that is solid element sulfur, the product is not only easy to transport can also be repeated re-use.
The selective catalytic reduction of SO2 by elemental sulfur method are mostly at the research stage.
Problems is excess oxygen in flue gas to the problem of the interference reduction process and catalyst poisoning problem.
Three catalytic oxidation of high concentration of refractory organic wastewater treatment with the development of medicine, chemical, dyes and other industries, more and more high concentration of refractory wastewater, they are the characteristics of the wastewater pollutant toxicity, pollutant concentration is high, difficult to biodegradation;
A high content of inorganic salts.
This kind of wastewater treatment is one of the most effective method of chemical oxidation method.
The efficient wet catalytic oxidation technology is a hot research topic.
This method can direct oxidation of organic pollutants in the water or to macromolecular organic pollutants in water oxidation into small molecular organic pollutants (pops), in order to improve the wastewater biological sex.
Together with the biochemical method after processing can well remove the organic pollutants in the water.
The method commonly used oxidant to increase the ability of catalytic oxidation of organic pollutants, can use the oxidant are: air, hydrogen peroxide, ozone, sodium hypochlorite and chlorine dioxide.
This method is the key to efficient heterogeneous oxidation catalyst development.
4 types and use status of environmental catalyst has a variety of the content of the earth's environment problem, now eager to solution of the problem are: the greenhouse effect, ozone depletion, acid rain, heavy metals, such as failure to environmental pollutants discharge, the decline of the tropical rain forest and soil desertification and so on.
The top three issues, which is caused by a chemical emissions to the atmosphere.
For example, carbon dioxide (
And the nitrogen oxide (
Are related to the greenhouse effect, freon and N2O destruction of the ozone layer, sulfur dioxide (
And NOX are a major factor in the formation of acid rain and smog, remove or reduce these pollutants, mainly through chemical methods to solve.
Due to the pollution of the reactants involved in the process of discharge amount is low, the reaction temperature too high or too low, the characteristics of reactants and catalyst special short contact time, therefore, environmental protection catalysts compared with other chemical reaction with the catalyst, the activity and selectivity of the catalysts and the durability of more demanding, it is harder to make.
5 new green catalyst 2.
1 montmorillonite silicate materials such as the structure of natural clay has kind of molecular sieve, catalyst carrier and good treatment of wastewater containing heavy metal ion adsorbent.
It is widely as automobile exhaust purification, flue gas desulfurization and denitration and environmental protection such as organic exhaust gas catalytic combustion is the carrier of catalyst.
2 TiO2 is a kind of n-type semiconductor, has the good photosensitive electrical conductivity, often be a catalyst carrier.
TiO2 is now widely used light catalyst, catalyst and electrode coated with activity of TiO2 self-cleaning glass, ceramic tile, furniture, curtain cloth, in the sunlight and automatic below the illuminate of lamplight catalysis and purification of indoor air.
3 biocatalysis technology usually in the biological materials as the raw material of non-toxic harmless, can reaction under atmospheric pressure, the process is simple.
Biological catalyst conversion rate high, strong specificity, less by-products, can be used repeatedly, thus is an ideal green catalyst.
4 can be used as acid catalyst, room temperature ionic liquids is a kind of green solvents.
Has to make convenient, low toxicity, low price, not burning, adjustable performance advantages, is predicted to be likely to cause a chemical industrial revolution and the industrial application prospect is good environmental friendly catalyst.
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