Schottky diodes with thin catalytic gate metals for potential use as ammonia sensors for exhaust gases
1999 (English)In: Sensors and materials, ISSN 0914-4935, Vol. 11, no 5, 305-318 p.Article in journal (Refereed) Published
Selective catalytic reduction (SCR) is a method in which ammonia reacts with nitric oxides in a catalytic converter to form water and nitrogen. We show that catalytic Metal Insulator Silicon Carbide (MISiC) devices can be used as ammonia sensors for a SCR system in a diesel engine. Different catalytic metals, Pt and Ir, with a thickness of 30 or 50 nm were investigated. The temperature dependence of the ammonia response of the sensors was characterized. Maximum responses were found at temperatures between 225-250 degrees C. Preliminary experiments were performed to investigate how annealing in different gas ambient influences the response-temperature curve of the sensors. In synthetic diesel exhausts with ammonia added, the sensors showed very good selectivity for ammonia and a small interaction effect with oxygen. The influence of other gas components was almost negligible. Temperature in the diesel exhaust system can reach 550 degrees C; however, operating at temperatures above 400 degrees C limited the lifetime of the sensor. Anger electron spectroscopy (AES) revealed that island formation of the metal due to structural changes was the main reason for failure of the sensor.
Place, publisher, year, edition, pages
Scientific Publishing Division Myu , 1999. Vol. 11, no 5, 305-318 p.
gas sensor; SiC; ammonia; exhaust gases
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-88121ISI: 000083267800005OAI: oai:DiVA.org:liu-88121DiVA: diva2:601806