Method and sensing element for measuring a gas in a gas mixture

摘要

A process determines the proportion of a specific gas to be oxidized, within a mixture of automotive exhaust gases. In a first stage, the process employs a gas sensor which first partly or wholly removes hydrogen or carbon monoxide from the exhaust gas sample. In a second stage, the concentration of a third gas is measured in a sample from which nitric oxides, carbon monoxide and/or hydrogen has been removed. The secondary electrodes within the sensor reduce most of the nitric oxides, and remove most of the hydrogen or carbon monoxide from the mixture. An independent claim is included for an automotive exhaust gas sensor assembly for use in the above method with an operating voltage of 350 - 500 mV for hydrogen and/or carbon monoxide, and 400 - 600 mV for nitric oxide.