Automotive Applications of Sol-Gel Processed Materials: Novel, Low Power Consumption, Electrically Heatable Catalyst Devices

ABSTRACTExhaust gas heat is the primary source of warming in a conventional automotive exhaust catalyst. It typically becomes operational within minutes after the initial start-up of an engine, when it attains temperatures greater than approximately 350°C. However, around 70% of the total hydrocarbon and carbon monoxide (CO) emissions of a modern gasoline powered vehicle, under a normal driving cycle, are released during this period of cold-start. One of the strategies suggested to treat the pollutants during the first minute after initial start-up involves electrically heating the catalyst. However, devices developed for this purpose are power intensive, can require a second battery and can reduce fuel economy. The increased weight, in turn, results in increased pollution. Here we describe a low power consumption prototype which contains a conducting layer beneath the washcoat. The prototype [4 cm2] was tested at a gas flow rate of 100 seem and required less than 5 Watts to attain temperatures greater than 350°C in less than 10 seconds. The prototype was tested in a flow reactor and found to rapidly heat up to light-off temperatures where the conversion of the hydrocarbons and CO takes place. We also summarize progress made in our laboratory in the fabrication of a test device employing sol-gel processed metal oxide films.