Although Korean domestic production of flat panel displays totalled more than 48 trillion KRW in 2007, most of the flat panel display wastes have been land-filled or incinerated, which greatly overshadows Korean national prestige as a world leading producer and developer of flat panel display devices. Countries such as Japan or EU possess quite limited landfill capability and have sought ways to dispose of WEEEs from environment-friendly perspective rather than recovery of valuable materials from the wastes. Considering relatively short cycle of about 5 years for flat panel display devices, it is estimated that more than 5 million units will be accumulated as wastes by 2015. Urban mining is a most suitable countermeasures against China's monopoly of rare and rare earth metals, which are contained in flat panel display wastes. Therefore, materials recycling of waste LCD units has to be developed and commercialized soon enough for economic and environment-friendly recovery of valuable resources hidden in LCD wastes.
This paper reports on the individual activity and selectivity of Fe-, Pd- and Pd – Fe-mordenite catalysts prepared by wet Fe-ion exchange and Pd-ion impregnation for N2O reduction using simulated hydrocarbon-selective catalytic reduction operation conditions of nitric acid plants. Laboratory-scale data on the activity, selectivity and characterization of Fe-, Pd-, and Pd – Fe-mordenite catalysts for conversion of N2O have been obtained under the simulated hydrocarbon-selective catalytic reduction operating condition in the temperature range of 325 – 400 °C encountered in nitric acid plant tail gases. More specifically, Pd-, Fe- and Pd – Fe-mordenite catalysts with Si/Al ratios of 10.25 – 10.65 were prepared. Wet ion-exchange methodology was used to prepare Fe-mordenite catalyst, whilst Pd-ion impregnation was used to prepare Pd-, and Pd – Fe-mordenite catalysts. Catalytic activities could not be consistently correlated with and explained by X-ray absorption near edge spectroscopy spectra. Further analysis by temperature-programmed desorption of ammonia was performed to explain higher catalytic activity of Pd – Fe-mordenite compared to Fe-, and Pd-mordenites. Higher catalytic activity of Pd – Fe-mordenite is most probably attributable to the presence of strong Lewis type acid centers as manifested by a TPD spectrum peak at about 300 °C.
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