Preparation, Characterization And Performance Of La Doped Sno2 Catalytic Pellet For Detection Of Volatile Organic Compounds
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Date
2010-10
Authors
Ang, Gaik Tin
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
SnO2 catalytic pellets doped with 0-10 atomic % lanthanum were developed
by sol gel method and characterized by X-ray diffraction (XRD), transmission
electron microscope (TEM), surface analysis (Nitrogen adsorption-desorption) and
scanning electron microscope (SEM). Prior the gas sensor measurement, LabVIEW
software was programmed to interface with the electrometer to get all measured
electrical resistance values. The electrical resistance change of the catalytic pellets
was investigated using volatile organic compound (VOC) vapours i.e. ethanol,
acetone and methanol in the air at the temperatures between 150-350oC.
The sensitivity of the SnO2 catalytic pellet was greatly enhanced by the
addition of lanthanum. The sensitivity of 5.0 atomic % La doped in SnO2 was up to
50.52 for 500ppm ethanol at working temperature of 250oC, while that of pure SnO2
is 14.84. The improvement in sensitivity may be attributed to the formation of small
SnO2 crystallite size, high surface area and the presence of the basic sites, which
facilitated the dehydrogenation process. Increasing of La content in the catalytic
pellet up to 7.5 atomic % deteriorated the ethanol sensitivity. Additionally the dopant
La in SnO2 sensors showed good selectivity to ethanol over methanol and acetone.
The 5.0 atomic % La-doped SnO2 exhibited very short response time of 14 seconds
with the high sensitivity value of 29.9 for the detection of 100 ppm of ethanol. The
linear dependence of the sensitivity on the ethanol concentration is observed in the
range of 100-1500 ppm.
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Keywords
Chemical Technology