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US 5,314,828 AGranted
NO.sub.x sensor and process for detecting NO.sub.x
AssigneeCatalytica, Inc.
InventorsRalph A. Dalla Betta, David R. Sheridan, Daniel L. Reed
Life of this patent
Estimating the term…
Abstract
This invention is a process for detecting low levels of nitrogen oxides (NO.sub.x) in a flowing gas stream (typically an exhaust gas stream) and a catalytic NO.sub.x sensor which may be used in that process.
Claims22
A device for measuring various nitrogen oxides (NO.sub.x) concentration in a flowing gas stream comprising:
- a. a catalytic sensor element comprising a catalyst for reducing NO.sub.x to N.sub.2 in the presence of a NO.sub.x reductant which catalyst is coated upon a temperature measuring device, where the catalyst and temperature measuring device are situated so that the catalytic contacts the flowing gas stream, and the heat produced by reducing NO.sub.x raises the temperature of the temperature measuring device substantially proportional to the NO.sub.x concentration in the flowing gas stream;
- b. a reference element for detecting the ambient temperature of the flowing gas stream in the vicinity of the catalytic sensor element;
- c. a NO.sub.x reductant source introducing NO.sub.x reductant into the flowing gas stream for contact with the catalytic sensor element;
- and
- d. a flowing gas stream temperature controller for controlling the temperature of the flowing gas stream prior to its passage over the catalytic sensor element to operating temperature.
2 more elements
A process for measuring various nitrogen oxides (NO.sub.x) in a flowing gas stream comprising the steps of:
- a. introducing a NO.sub.x reductant into the flowing gas stream containing NO.sub.x to produce a mixed stream,
- b. controlling the temperature of the flowing gas stream to an appropriate operating temperature, and
- c. passing the mixed stream to a catalytic sensor comprising a catalyst for reducing NO.sub.x to N.sub.2 with the NO.sub.x reductant upon contacting the mixed stream and a temperature measuring device where the catalyst and temperature measuring device are situated so that the heat produced by reducing NO.sub.x with the catalyst raises the temperature of the temperature measuring device substantially proportional to the NO.sub.x concentration in the mixed stream where the temperature measuring device provides a measurable output related to the temperature rise.
Dependencies are inferred from the claim text.