Patent ID: 6344173
Filing Date: 2002-02-05
Classification: G01N,Y10T

Abstract:
A sensor for measuring the hydrocarbon concentration of a CO+H2+hydrocarbon containing gas sample, comprising:a sensor base, capable of producing a output signal representative of the exothermic effect of the hydrocarbon species in the gas sample, the sensor base having disposed on, and integral with, its surface a porous selective oxidation catalyst layer capable of selectively oxidizing a combination of CO+H2+alkene species in the gas sample and leaving unoxidized the alkane and aromatic hydrocarbons; the sensor base further comprising a first supported resistance temperature device, having disposed thereon a total oxidation catalyst layer capable of oxidizing the remaining alkane and aromatic hydrocarbon species in the gas sample and comprising a high surface area catalyst-support material and a precious metal material supported thereon, and a non-catalyzed second resistance temperature device; the porous selective oxidation catalyst layer being comprised of a high surface area silica catalyst-support material having a thickness of 0.1 to 10 &mgr;m with a precious metal comprising rhodium in the form of highly dispersed rhodium cluster deposits being disposed on the silica catalyst-support material, the rhodium cluster deposits comprising a single rhodium atom or a cluster of at least two rhodium atoms having a diameter of less than about 5 nm and covering no greater than about 10% of the surface area of the catalyst-support material.