Increasing air pollution is a serious concern, because cleaning of gas emissions every year becomes more and more urgent.The largest source of emissions of harmful gases in the atmosphere are energy industries and road transport.
gas emissions purification is carried out in various ways, among which the most effective in many cases is the catalytic method of neutralization and reducing the concentration of pollutants to the maximum permissible level.Catalytic cleaning is preferred, and for economic reasons.
Typically, catalytic methods are universal and can be used for deep cleaning of various process gases.With this method it is possible to purify industrial gases from nitrogen oxides, and sulfur, carbon monoxide, harmful organic compounds and other toxic contaminants.Wherein contaminants are converted into less harmful and harmless, and sometimes even useful.The same way by cleaning the exhaust gases.In essence, the method consists in implementing processes of chemical interaction of the substances in the presence of catalysts, resulting in conversion of impurities to be neutralizing in other products.
Special catalysts accelerate chemical reactions, but it does not affect the energy level of the interacting molecules and not to shift the equilibrium of simple reactions.Catalytic cleaning promising for multicomponent mixtures of flue gas streams.For gas cleaning in industry are used as catalysts oxides of iron, copper, chromium, cobalt, zinc, platinum and others.These substances handled catalyst support is placed inside the reactor unit.It is necessary to monitor the integrity of the outer layer of the catalyst, otherwise the catalytic cleaning is not carried out in full, and emissions may exceed permissible levels.
main requirement is that the catalyst - the stability of the structure during the reaction.Search and manufacture of catalysts is not only suitable for continuous operation, but also sufficiently cheap, is a certain difficulty which limits the use of catalytic methods.Modern catalysts should possess selectivity and activity, resistance to temperatures and mechanical strength.
Industrial catalysts manufactured in the form of blocks and the rings of the honeycomb structure.They have a low flow resistance and high external surface area.Most often used catalytic purification of gases in a fixed catalyst.
The industry can use two fundamentally different ways of the gas treatment processes - stationary and non-stationary mode artificially created.Go to the predominant use of non-stationary method due to higher adaptability of the process, increase the reaction rate, an increase in selectivity, lower energy intensity of processes, reduction of capital costs for installation and reduction of the cost of its operation.
main direction of development of catalytic techniques is to provide a cheap catalyst that can operate at low temperatures and be resistant to various substances.For concentrations of less than 1 g / m and with large volumes of purified gases thermocatalytic method requires high energy costs and a huge amount of the catalyst, so there is a need to develop the most energy-efficient processes and equipment requiring low capital costs.
