Development of a new gas sensor for binary mixtures based on the permselectivity of polymeric membranes Application to carbon dioxide/methane and carbon dioxide/helium mixtures

Membrane-based gas sensors were developed and used for determining the composition on bi-component mixtures in the 0–100% range, such as oxygen/nitrogen and carbon dioxide/methane (biogas). These sensors are low cost and are aimed at a low/medium precision market. The paper describes the use of this sensor for two gas mixtures: carbon dioxide/methane and carbon dioxide/helium. The membranes used are poly(dimethylsiloxane) (PDMS) and Teflon-AF hollow fibers. The response curves for both sensors were obtained at three different temperatures. The results clearly indicate that the permeate pressure of the sensors relates to the gas mixture composition at a given temperature. The data is represented by a third order polynomial. The sensors enable quantitative carbon dioxide analysis in binary mixtures with methane or helium. The response of the sensors is fast (less than 50 s), continuous, reproducible and long-term stable over a period of 2.3×10^7 s (9 months). The absolute sensitivity of the sensors depends on the carbon dioxide feed concentration ranging from 0.03 to 0.13 MPa.