Thermocatalytic detection of NOx in vehicle exhaust

Conference · Tue Jan 01 04:00:00 EST 1974

OSTI ID:7182717

Innes, W B

A system for thermocatalytic detection of nitrogen oxides is described along with test results from measurements on light combustion gases and automobile exhaust streams. Sample gas is syringe injected into a gallon bottle containing room air, followed by insertion of the sampling probe into the bottle; ammonia may also be added via a capillary to the gas stream. After preheating, the mixture passes through the catalytic reactor containing a vanadia catalyst and a glass coated chromel-constantan thermocouple detector and then exits into a vacuum pump. The detector output is measured with a microvoltmeter, with a reading of 80 microvolts corresponding to about a 1/sup 0/C temperature rise. Findings are reported for various temperatures, flow rates, and ammonia/nitric oxide ratios, with the results appearing consistent with a highly exothermic first order reaction of high rate above 300/sup 0/C. Tests for possible interferences from carbon monoxide and hydrogen in vehicle exhaust gases were conducted for 1% levels of H/sub 2/ and CO on response to 540 ppm NO at 2:1 NH/sub 3//NO at 1.0 CFH at 395/sup 0/C and indicate no detectable effect from the CO or H/sub 2/. Tests conducted on light combustion gases for sulfur dioxide interference at levels up to 0.5% also indicated no significant effect at 1 CFH and 395/sup 0/C.

• OSTI ID: 7182717
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
330701* -- Emission Control-- Nitrogen Oxides
AMMONIA
AUTOMOBILES
CATALYSTS
CHALCOGENIDES
EXHAUST GASES
GASEOUS WASTES
HYDRIDES
HYDROGEN COMPOUNDS
MEASURING METHODS
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NITROGEN OXIDES
OXIDES
OXYGEN COMPOUNDS
SAMPLING
TEST FACILITIES
THERMOCHEMICAL PROCESSES
VEHICLES
WASTES