Many of the pollutants created when burning biomass are the result of incomplete combustion, for example carbon monoxide, VOCs, tar compounds, etc. Catalytic oxidation can be regarded as a secondary combustion process in which any organic compounds left over from the primary combustion are oxidised into carbon dioxide and water.
Catalytic oxidation is temperature-dependent, and generally requires temperatures in the range 250-450°C to be effective. However, this is significantly lower than is required for non-catalytic oxidation techniques, such as the use of afterburners, and therefore it is often a more economical and environmentally-friendly solution.
When designing a catalytic oxidation system for a large-scale biomass application, the temperature of the flue gases is always the first consideration. The next stage is to think about chaff and dust, to ensure that the design of the catalytic converter prevents it becoming blocked up. Thirdly, we need to consider corrosive substances in the flue gas such as sulphur and chlorine which can shorten the life of the catalyst unless specialist coatings are used.