Calorimetric Thermoelectric Gas Sensor for the Detection of Hydrogen, Methane and Mixed Gases

A novel miniaturized calorimeter-type sensor device with a dual-catalyst structure was fabricated by integrating different catalysts on the hot (Pd/θ-Al(2)O(3)) and cold (Pt/α-Al(2)O(3)) ends of the device. The device comprises a calorimeter with a thermoelectric gas sensor (calorimetric-TGS), combining catalytic combustion and thermoelectric technologies. Its response for a model fuel gas of hydrogen and methane was investigated with various combustor catalyst compositions. The calorimetric-TGS devices detected H(2), CH(4), and a mixture of the two with concentrations ranging between 200 and 2000 ppm at temperatures of 100–400 °C, in terms of the calorie content of the gases. It was necessary to reduce the much higher response voltage of the TGS to H(2) compared to CH(4). We enhanced the H(2) combustion on the cold side so that the temperature differences and response voltages to H(2) were reduced. The device response to H(2) combustion was reduced by 50% by controlling the Pt concentration in the Pt/α-Al(2)O(3) catalyst on the cold side to 3 wt%.