초록 ▼

A method and apparatus for the chemiluminescent determination of NO/NOx in a sample gas is disclosed in which the NOx portion of the gas stream is catalytically converted in a preconditioned vitreous carbon bed at a relatively low temperature effective to catalytically convert NOx to NO and below 20

A method and apparatus for the chemiluminescent determination of NO/NOx in a sample gas is disclosed in which the NOx portion of the gas stream is catalytically converted in a preconditioned vitreous carbon bed at a relatively low temperature effective to catalytically convert NOx to NO and below 200°C. The vitreous carbon is preconditioned by heating at a temperature of between 300°C. and about 500°C. for a sufficient period of time, on the order of two to five hours. The apparatus consists of a converter containing the preconditioned vitreous carbon in communication with a reaction cell consisting of a hollow cylindrical housing having an open end closed by an optical filter. A suitable photodetecter is disposed to detect light emitted through the optical filter. A chemiluminescent reaction between ozone and NO in the sample stream occurs in a reaction chamber defined by the interior of the housing. A reflector element may be disposed in the reaction chamber. The converter and the housing are preferably formed of low cost, easily worked materials, such as stainless steel or aluminum.

대표청구항 ▼

In a method for the determination of the concentration of NOx in a gas stream by the catalytic conversion of NOx to NO, mixing the NO with ozone in a reaction chamber to cause a chemiluminescent reaction therebetween and determining the light output of said reaction as a measure of the concentration

In a method for the determination of the concentration of NOx in a gas stream by the catalytic conversion of NOx to NO, mixing the NO with ozone in a reaction chamber to cause a chemiluminescent reaction therebetween and determining the light output of said reaction as a measure of the concentration of the NOx in said sample, the invention comprising the steps of: a. preconditioning a catalyst comprising vitreous carbon by heating said vitreous carbon to a temperature in excess of 300°C. for at least two hours; b. forming a converter comprising a housing and a bed of said preconditioned vitreous carbon and heating said bed of vitreous carbon to a temperature effective to convert NOx to NO and less than 200°C.; and c. passing said gas stream through said converter to convert a major portion of the NOx concentration thereof to NO.