NOx sensor

A NOx sensor comprising:

• a gas detection chamber composed of an internal space formed by a first zirconia solid electrolyte substrate having oxygen ion conductivity, an opposed second zirconia solid electrolyte having oxygen ion conductivity, and a spacer separating said zirconia solid electrolyte substrates;
• a NOx detection cell including a NOx sensing electrode fixed onto one side of said first zirconia solid electrolyte substrate in said gas detection chamber, said NOx sensing electrode being active to NOX and oxygen, and a reference electrode fixed onto the other side of said first zirconia solid electrolyte substrate, said reference electrode being active to at least oxygen;
• a NOx conversion pumping cell including a NOx conversion electrode fixed onto said second zirconia solid electrolyte substrate in said gas detection chamber, said NOx conversion electrode being active to NOx and oxygen, and a counter electrode to be paired with said NOx conversion electrode, said counter electrode being fixed onto said second zirconia solid electrolyte substrate, being active to oxygen;
• voltage applying means for applying a predetermined voltage to said NOx conversion pumping cell;
• a first gas treatment chamber communicating with said gas detect ion chamber and having a gas inlet leading to an atmosphere of a gas to be detected;
• an oxidation catalyst pumping cell including an oxidation catalyst electrode arranged in said first gas treatment chamber, said oxidation catalyst electrode having a gas channel, being active to a reducing gas and oxygen, and serving as an anode electrode, and a cathode electrode to be paired with said oxidation catalyst electrode, said cathode electrode being arranged on a zirconia solid electrolyte substrate outside said gas detection chamber and being active to oxygen;
• voltage applying means for applying a predetermined voltage to said oxidation catalyst pumping cell;
• and
• means for measuring a potential difference between said NOx sensing electrode and said reference electrode NOx when NOx in the gas to be detected is converted into NO2 or NO by said NOx conversion pumping cell after the reducing gas in the gas to be detected is oxidized in said first gas treatment chamber, and thereby detecting the total NOx concentration in the gas to be detected.

A NOx sensor comprising:

• a gas detection chamber composed of an internal space formed by a first zirconia solid electrolyte substrate having oxygen ion conductivity, an opposed second zirconia solid electrolyte having oxygen ion conductivity, and a spacer separating said zirconia solid electrolyte substrates;
• a NOx sensing cell including a NOx sensing electrode fixed onto one side of said first zirconia solid electrolyte in said gas detection chamber, said NOx sensing electrode being active to NOx and oxygen, and a reference electrode fixed onto the same side of said first zirconia solid electrolyte substrate, said reference electrode being active to oxygen and inactive to NOx;
• a NOx conversion pumping cell including a NOx conversion electrode fixed onto said second zirconia solid electrolyte substrate in said gas detection chamber, said NOx conversion electrode being active to NOx and oxygen, and a counter electrode to be paired with said NOx conversion electrode, said counter electrode being fixed onto said second zirconia solid electrolyte substrate, being active to oxygen;
• voltage applying means for applying a predetermined voltage to said NOx conversion pumping cell;
• a first gas treatment chamber disposed between said gas detection chamber and a gas inlet leading to an atmosphere of a gas to be detected;
• an inorganic porous member with a porosity of 5-40% by volume being loaded into only said first gas treatment chamber;
• and
• means for measuring a potential difference between said NOx sensing electrode and said reference electrode while converting NOx in the gas to be detected into single component after a reducing gas in the gas to be detected is oxidized in said first gas treatment chamber, and thereby detecting a total NOx concentration in the gas to be detected.

A NOx sensor comprising:

• a gas detection chamber composed of an internal space formed by a first zirconia solid electrolyte substrate having oxygen ion conductivity, an opposed second zirconia solid electrolyte having oxygen ion conductivity, and a spacer separating said zirconia solid electrolyte substrates;
• a NOx detection cell including a NOx sensing electrode fixed onto one side of said first zirconia solid electrolyte substrate in said gas detection chamber, said NOx sensing electrode being active to NOx and oxygen, and a reference electrode fixed onto the same side of said first zirconia solid electrolyte substrate, said reference electrode being active oxygen and inactive to NOx;
• a NOx conversion pumping cell including a NOx conversion electrode fixed onto said second zirconia solid electrolyte substrate in said gas detection chamber, said NOx conversion electrode being active to NOx and oxygen, and a counter electrode to be paired with said NOx conversion electrode, said counter electrode being fixed onto said second zirconia solid electrolyte substrate, being active to oxygen;
• voltage applying means for applying a predetermined voltage to said NOx conversion pumping cell;
• a first gas treatment chamber communicating with said gas detection chamber and having a gas inlet leading to an atmosphere of a gas to be detected;
• an oxidation catalyst pumping cell including an oxidation catalyst electrode arranged in said first gas treatment chamber, said oxidation catalyst electrode having a gas channel, being active to a reducing gas and oxygen, and serving as an anode electrode, and a cathode electrode to be paired with said oxidation catalyst electrode, said cathode electrode being arranged on a zirconia solid electrolyte substrate outside said gas detection chamber and being active to oxygen;
• voltage applying means for applying a predetermined voltage to said oxidation catalyst pumping cell;
• and
• means for measuring a potential difference between said NOx sensing electrode and said reference electrode while converting NOx in the gas to be detected into NO2 or NO by said NOx conversion pumping cell after the reducing gas in the gas to be detected is oxidized in said first gas treatment chamber, and thereby detecting the total NOx concentration in the gas to be detected.