Abstract: A method and catalytic systems for treating a gas to reduce nitrogen oxide emissions are disclosed. The catalytic systems can include a catalytic composition which comprises an active phase on a support. The active phase is based on rhodium in the form RHx+ and at least another element selected among palladium and platinum and the support is based on cerium oxide and zirconium oxide. Gases capable of being treated by the method and the catalytic systems include in particular those derived from gas turbines, from gas-fired or coal-fired stream plant boilers, or from internal combustion engines.

Abstract: The invention concerns a method for treating a gas to reduce nitrogen oxide emission. Said method is of the type using a catalytic composition comprising an active phase on a support and is characterised in that the active phase is based on rhodium in the form Rhx+ and at least another element selected among palladium and platinum and the support is based on cerium oxide and zirconium oxide. Gases capable of being treated by said method include in particular those derived from gas turbines, from gas-fired or coal-fired steam plant boilers or from internal combustion engines.