Benzpyrene exhaust gas cleaning

Authors: Aleksandr Makarov, Ph. D., Dmitry Fotin, Ph. D., ECAT Company

The huge percent of benzpyrene emissions comes from chemical-recovery and metallurgical enterprises, recycling factories. Nowadays the main method of benzpyrene exhaust gas reducing is technological process optimization.

Pollution decomposition is a very important ecological problem. That is why it demands the complex approach.Benzpyrene is the chemical carcinogen of environment.It is very dangerous chemical compound for people even at small concentrations.

The benzpyrene decomposition is complicate due to high temperatures of it generation and neutralization. That is why the plasma-catalytic decomposition is not suitable for this substance in spite of its advantages (low operating costs). This kind of cleaning does not work with high temperatures. Nowadays the most effective kind of benzpyrene decomposition is the thermal catalysis.

The special feature of ECAT catalytic technology is the usage of nanostructural catalyst as the basis of the foam materials.

For benzpyrene decomposition on the industrial enterprises the ECAT company produces the unique catalyst based on nickel foam with a secondary carrier coverage and a catalytic La-Ag-Mn-O layer.

Catalysts based on foam materials have a lot of advantages in comparison with others. One of the main foam materials advantages is the unique cellular net structure which promotes ntensive mass exchange and heat exchange with environment flowing through the catalyst. Moreover, such structure influences duration of interaction of gas with a working surface, increasing time of reaction. Absence of through channels reduces probability of reagents overshoot at high specific loads. Due to it the maintenance of precious metals in catalysts essentially decreases in comparison with the similar catalysts based on cellular ceramics.

For the foam material catalyst tests were used the following (fig.1): Compressed air from the compressor (1) arrived in thermostatic flask (100°Ñ) with 3 l/min speed. The advance speed was regulated by a float rotameter. The broken ampoule with benzpyrene was placed into the flask (2).Submitted oxygen of air was used as benzpyrene oxidizer and its «carrier» to thermal catalysis zone. After this the benzpyrene mix/air with 35–40°Ñ temperature came to running catalytic reactor (4) which had been temperature-controlled at 450°Ñ in muffle burner (3). The temperature of reaction in the reactor was 450°Ñ. After that the flow came to the filter (5) which adsorbed the rests of benzpyrene. The aspirator (6) was necessary for the fixed fence of air from the reactor with 3 l/min speed.

Figure 1. Laboratory plant for the catalyst tests.

Measurements of the maintenance of benzpyrene quantity was produced by high-performance liquid chromatography. Determination of the catalyst efficiency defined as a ratio of benzpyrene quantity on «input» and «output» from the reactor.

Thereby the tests have shown high activity of benzpyrene oxidation processes of catalysts based on foam materials with the catalytic La-Ag-Mn-O layer. Efficiency of oxidation has reached not less than 97%.

Successful tests prove the possibility of using thermal catalyst systems (Fig.2) at the industrial enterprises for the benzpyrene decomposition for achievement of over then 95% cleaning.

Figure 2. 3D Model of thermal catalyst system by ECAT Company (1000 m3/h).