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oa Supported gold nanocatalyst for low temperature CO oxidation and combustion of volatile organic compounds (VOC)
- الناشر: Hamad bin Khalifa University Press (HBKU Press)
- المصدر: Qatar Foundation Annual Research Forum Proceedings, Qatar Foundation Annual Research Forum Volume 2010 Issue 1, ديسمبر ٢٠١٠, المجلد 2010, EEP6
ملخص
Carbon monoxide (CO) and volatile organic compounds (VOC), such as butadiene and isoprene, are air pollutants emitted by many industrial sources, such as burning of wood and fuel with poor ventilation, and by natural sources including forest fires or volcanic eruptions. It was found that these compounds are also significantly abundant in many industrial processes. Therefore, low-temperature catalytic oxidation of CO and combustion of VOC is one of the most important problems in catalysis, since even small exposures to CO or VOC (ppm) can be lethal. Catalytic oxidation is one effective method of removing CO.
Nanoparticle catalysts are characterized by a large surface area, high dispersion and strong metal-support interaction. It is therefore expected that nanoparticle catalysts would show high catalytic activity for the low temperature oxidation of CO.
Our results demonstrate the application of the vapor phase synthesis to synthesize supported and unsupported nanoparticle catalysts for CO oxidation. The method is based on the laser vaporization/controlled condensation (LVCC) technique of gold (Au) and copper (Cu) nanoparticles supported on a variety of oxide supports such as CeO2, TiO2, CuO and MgO. Our results indicate that Au nanoparticles supported on CeO2 exhibit higher catalytic activity than Au supported on other oxides. This high activity is attributed to the strong interaction of Au with CeO2. The results also indicate that 5 % Au loading on CeO2 has higher activity than 2% Au or 10% Au.
The effect of preparation method on the catalytic activity is investigated. It was found that the catalytic activity for 5%Au/CeO2 prepared by the chemical (deposition-precipitation) method is higher than the catalytic activity of Au/CeO2 prepared by physical (LVCC).
In any combustion system, there are significant amounts of other toxic gases,besides CO, such as nitric oxide, butadiene, and isoprene. We investigated the catalytic activity of the Au/CeO2 nanoparticle catalyst in the presence of 1000 ppm of butadiene and in the presence of 1000 ppm of isoprene. Our results indicate the combustion of butadiene and isoprene to CO2 and H2O, as supported by the mass spectrum and the CO conversion curve.
Finally, the Au/CeO2 nanoparticle catalyst can be an active catalyst for selective CO oxidation at temperatures below 300oC even in the presence of VOC. Furthermore, this catalyst shows great promise for the low temperature combustion of VOC such as butadiene and isoprene.