Adsorption based carbon monoxide sensor and method

• US 6,474,138 B1
• Filed: 11/28/2000
• Issued: 11/05/2002
• Est. Priority Date: 11/28/2000
• Status: Expired due to Fees

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Chang, Chin H., Bonne, Ulrich, Alderman, Richard A.
• Primary Examiner(s): LARKIN, DANIEL SEAN
• Application Number:
  US09/724,536
• Time in Patent Office: 707 Days
• Field of Search: 73/233.1, 73/250.1, 73/250.5, 73/310.5
• US Class Current: 73/25.01
• CPC Class Codes: G01N 25/30 using electric temperature-responsive elements
• CPC Class Codes: G01N 33/004 CO or CO2
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

A carbon monoxide sensor and method is shown and described. The sensor includes a sensing element that includes an adsorbent dispersed over a support material. The adsorbent is capable of exothermically adsorbing carbon monoxide. The sensor also includes a temperature sensor in contact with the sensing element and a signal processing module coupled to the temperature sensor. The temperature sensor communicates signals indicative of a temperature increase of the sensing element to the processing module, thereby indicating an adsorption and, therefore, a presence of carbon monoxide.

Claims

1. A carbon monoxide sensor comprising:

a sensing element;

a temperature sensor;

a signal processing module in communication with the temperature sensor;

the sensing element comprising an adsorbent dispersed over a support material, the adsorbent capable of exothermally adsorbing carbon monoxide; and

the temperature sensor sending signals indicative of the temperature of the sensing element to the processing module.

2. The carbon monoxide sensor of claim 1 further comprising a heating element to heat the sensing element to a temperature that is at least as high as the desorption temperature of carbon monoxide adsorbed onto the sensing element thereby resulting in an desorption of the carbon monoxide adsorbed by the adsorbent and a regeneration of the adsorbent.

3. The carbon monoxide sensor of claim 2 further comprising a permeable membrane support substrate disposed in front of the sensing element, the temperature sensor, and the heating element.

4. The carbon monoxide sensor of claim 2 further comprising a protective membrane disposed behind the sensing element, the temperature sensor, and the heating element.

5. The carbon monoxide sensor of claim 1 wherein the adsorbent is selected from the group consisting of monovalent Ag⁺, monovalent Cu⁺, and mixtures thereof.

6. The carbon monoxide sensor of claim 1 wherein the support material is selected from the group consisting of zeolite, alumina, silica gel, carbonaceous materials, and mixtures thereof.

7. The carbon monoxide sensor of claim 1 wherein the temperature sensor is a first temperature sensor, and wherein the carbon monoxide sensor further comprises:

a reference element comprising a non-adsorbing material that does not adsorb carbon monoxide, and

a second temperature sensor, the second temperature sensor being coupled to the processing module and sending signals indicative of the temperature of the reference element to the processing module.

8. The carbon monoxide sensor of claim 7 wherein the heating element is a first heating element, and wherein the carbon monoxide sensor further comprises a second heating element to heat the reference element.

9. The carbon monoxide sensor of claim 8 wherein the first and second heating elements are in communication with one another.

10. A method of detecting a presence of carbon monoxide in a gas comprising the steps of:

exposing a sensing element comprising an adsorbent dispersed over a layer of a support material to the gas that comprises carbon monoxide, the adsorbent capable of exothermally adsorbing carbon monoxide;

adsorbing at least a portion of the carbon monoxide in the gas onto the adsorbent resulting in an increase in the temperature of the sensing element; and

using the temperature increase of the sensing element thereby indicating the presence of carbon monoxide in the gas.

11. The method of claim 10 further comprising the step of heating the sensing element to a temperature that is at least as high as the desorption temperature of carbon monoxide adsorbed by the adsorbent thereby resulting in a desorption of said carbon monoxide adsorbed by the adsorbent and a regeneration of the adsorbent.

12. The method of claim 10 wherein the sensing element further comprises a temperature sensor and a signal processing module in communication with the temperature sensor.

13. The method of claim 10 wherein the adsorbent is selected from the group consisting of monovalent Ag⁺, monovalent Cu⁺, and mixtures thereof.

14. The method of claim 13 wherein the support material is selected from the group consisting of zeolite, alumina, silica gel, carbonaceous materials, and mixtures thereof.

15. The method of claim 10 further comprising the steps of:

exposing a reference element comprising non-carbon monoxide adsorbing material to the gas;

sensing a temperature of the sensing element and a temperature of the reference element; and

,

subtracting the temperature of the reference element from the temperature of the sensing element to provide a net temperature increase of the sensing element.

16. A carbon monoxide sensor comprising:

a sensing element comprising an adsorbent dispersed over a support material, the adsorbent capable of exothermally adsorbing carbon monoxide,

a first temperature sensor to sense a temperature of the sensing element,

a reference element comprising a non-adsorbing material that does not adsorb carbon monoxide;

a second temperature sensor to sense a temperature of the reference element;

a signal processing module in communication with the first and second temperature sensors;

the first temperature sensor sending signals indicative of a temperature of the sensing element to the processing module and the second temperature sensor sending signals indicative of a temperature of the reference element to the processing module; and

a heating element to heat the sensing element to a temperature that is at least as high as the desorption temperature of carbon monoxide adsorbed by the adsorbent thereby resulting in a desorption of the carbon monoxide adsorbed by the adsorbent and a regeneration of the adsorbent.

17. The carbon monoxide sensor of claim 16 wherein the adsorbent is selected from the group consisting of monovalent Ag⁺, monovalent Cu⁺, and mixtures thereof.

18. The carbon monoxide sensor of claim 16 wherein the support material is selected from the group consisting of zeolite, alumina, silica gel, carbonaceous materials, and mixtures thereof.

19. The carbon monoxide sensor of claim 16 further comprising a permeable membrane support substrate disposed in front of the sensing element, the reference element, the first and second temperature sensors, and the heating element.

20. The carbon monoxide sensor of claim 16 further comprising a protective membrane disposed behind the sensing element, the reference element, the first and second temperature sensors, and the heating element.

21. The carbon monoxide sensor of claim 16 wherein the heating element also heats the reference element.