How do Zero Air Generators Work? Thermocatalytic Conversion
What is Zero Air?
Zero Air, defined as "Atmospheric air purified to contain less than 0.1 ppm total hydrocarbons" by the US Environmental Protection Agency, is a useful or necessary gas for several types of scientific and analytical devices.
How is Zero Air produced?
Zero Air can be produced in a number of ways that fall into two main categories Synthetic production and Catalytic processing. The first, Synthetic production, involves mixing existing pure supplies of oxygen and nitrogen together in a canister, this is typically has to be done on an industrial scale and requires the end user to handle and manage a supply of gas canisters.
Catalytic processing, on the other hand, allows Zero Air to be produced on demand as and when required and only requires supplies of compressed air and power for the generator. Catalytic processing uses two main methods: Photocatalytic conversion, where light is used to activate a catalyst and Thermocatalytic conversion where heat is used. Thermocatalytic conversion is the more efficient of the two and the one this article will focus on.
What is Thermocatalytic conversion and how does it work?
The term "Thermocatalytic" means a process that is driven by both a catalyst and heat.
In a Thermocatalytic Zero Air generator compressed air is first passed through a particulate filter then it is passed into a heat chamber. The chamber is heated to approximately 500°C and within it the air passes through a high surface area matrix that has been impregnated with a catalyst made up of a combination of exotic metals. As the now hot air passes over and around the catalyst any hydrocarbons, particularly methane, will react and begin oxidising, breaking down into Carbon Dioxide (CO2) and water (H20). The now hydrocarbon free air then exits the heated chamber, is cooled and passed through a final filter to remove bulk water. The Thermocatalytic method allows for highly efficient processing in a small unit and, as it will be operating at optimum perfromance as soon as the chamber is heated, a relatively fast start up time