Thermal Catalytic Oxidation also known as catalytic incinerators normally destruct gaseous waste at low concentrations of less than 25% of the LEL. Heat gases pass through a perforated plate to straighten the flow and then pass through a catalyst material prior to discharge.
The catalyst has the property of increasing the rate of oxidation at lower temperatures. Typically, the catalytic oxidation is carried on at a temperature around 360°C although temperatures of up to 820°C may be required for destruction of materials such as chlorinated organics.
Catalytic materials normally used are the noble metals, such as, platinum, palladium and rhodium. Other materials which function as catalysts are copper chromite and oxides of copper, chromium, manganese, nickel and cobalt.
The type of catalyst sections commonly used are the mat supported, Porcelain supported or Honeycomb supported catalyst. The gas stream must be free of particulate matter to protect the catalyst from fouling. If particulate matter is present, pre-treatment of the gas, such as cyclonic separation or electrostatic precipitators, may be necessary upstream of the catalyst.
Beside particulate fouling, catalysts are sensitive to a number of substances which may poison or suppress the catalyst.
As with direct flame incineration, the cost of heat exchanger equipment is often more then offset by the savings in supplemental fuel consumption and thus heat recovery systems are used to preheat the incoming combustion air and/or heat a stream for external use which can be gas or water for steam.