Catalytic processes work on a fundamental principle of catalysis. Catalysis is nothing but a technique used to increase the rate of a chemical reaction by adding an external substance called a catalyst. These catalysts used in the process are not consumed in the reaction and remain unchanged after it. In general, a tiny quantity of catalyst is required. These catalysts react with one or more reactants to form intermediates that subsequently give the final reaction product.
Catalysts can, in general, be classified as either homogeneous (whose components are dispersed in the same phase as the reactant) or heterogeneous (whose components are not in the same phase).
Catalysis is commonly used in all kinds of chemical industries. 90% of all commercially produced chemical products or activities involve catalysts at some stage or the other. Catalysis also plays a vital role in air pollution control systems in industries.
How does catalysis help in air pollution control?
Pollutants in the exhaust air turn into non-hazardous substances at a very high temperature, generally between 700-800 °C. This process requires a tremendous amount of energy, which is where a catalyst plays an important role. The catalyst brings down the reaction temperature by 300 to 500°C, saving a considerable amount of energy and cost.
In this air pollution control system, 2 factors need to be kept in mind. First, the exhaust gas temperature must exceed a specific temperature to ensure that the catalyst reacts.
Secondly, exhaust air may need preconditioning so that the unwanted particles are removed. This will help prevent catalyst poisoning, which deactivates the catalyst making it unusable and unable to perform. Catalyst poisoning prevents the catalyst from functioning as it covers its surface and slows down its effects.
How does Dürr play a vital role in providing air pollution control systems to industries in India?
Dürr provides a wide range of catalytic air pollution control systems in India designed to give excellent results with different types of pollutants and operating parameters. To understand Dürrs’ systems, it is vital to understand the difference between catalyst-based air pollution control systems and other fundamental processes used for air pollution control.
Dürr uses catalysts for oxidation and reduction processes majorly. It also offers a wide range of different systems to satisfy its customers’ requirements.
The portfolio of products includes the Cat.X PH, which helps purify the exhaust gas produced under very high pressure. Whereas in the Cat.X PL, the pollutants present are converted at the atmospheric pressure. Therefore, this system suits the best when the exhaust air consists of volatile organic compounds (VOCs).
Cat.X CF seems to be the best choice if substances like dust, sulphur, or nitrogen oxide must be extracted from the exhaust air. This filter allows a range of different substances to be eliminated simultaneously with the help of catalytic oxidation.
Cat.X RO – This system combines the best of both worlds, i.e. it provides the benefits of regenerative heat exchangers and catalytic oxidation. This process of regenerative catalytic oxidation (RCO) helps remove unpleasant odours as it reduces the level of pollutants in exhaust air volume flow with a low pollutant load.
The final system that uses the catalytic process is the Cat.X CR air pollution control system. This system is used explicitly for nitrogen oxides (NOx) in flue gases and processes exhaust gases when high nitrogen oxide conversation rates are required. This system is also known as selective catalytic reduction (SCR).