Synthesis and Optimization of Metal Oxide Catalysts Supported on Nano-structured Alumina for Oxidation of Toluene from Contaminated Air

Jafari, Mina | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45788 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Khorashe, Farhad; Kazemeni, Mohammad
  7. Abstract:
  8. Exhaust gases from poultry rendering facilities contain volatile organic compounds (VOCs) that are a nuisance, odorous, and smog and particulate matter precursors. Other available treatment options, such as thermal and catalytic incineration require temperature intensive inputs and form additional greenhouse gases. Hence, an inexpensive alternative technology is needed to eliminate these air pollutants. This research investigated the catalytic oxidation of toluene vapors using novel dispersed nano catalysts derived from new preparation method. The combined impregnation (IMP) and deposition-precipitation (DP) was used to prepare supported transition metal oxide catalyst over commercial and nano γ-alumina. A central composite design (CCD) was applied to study the effect of two important preparation parameters (metal loading and calcination temperature) for catalyst synthesis. The response surface methodology (RSM) was used to obtain reduced experiments for the catalyst preparation. In the first phase, supported copper, cobalt, iron and nickel catalysts were tested for toluene uptake data in a tubular packed reactor at 350 oC. The catalyst activity was measured in the plug reactor operated with placed 1gr powder sample at 166.67 ml/min of flow rate and toluene inlet concentration of 30000 ppm. It was found that the performance of copper catalysts with 3% and 8% wt loading were better than the other transition metals. In the second phase, thirteen suggested copper catalysts by design expert software were prepared and the removal efficiency of toluene was determined to study the effect of metal loading and calcination temperature. Catalyst activity increased with both increasing calcination temperature and metal loading. Calcination temperature had a significant effect on the catalyst activity only at high metal loadings. Three scenarios were investigated for enhancement of catalyst activity. Obtained results showed that catalyst activity was increasing as increasing the calcination temperature from 500 to 600oC, with further increasing in calcination temperature above 600 oC, the removal efficiency of toluene was reduced. In addition, using the nano structure support could not also improve the activity of copper catalysts. Comparison between preparation methods it was clearly obtained that HDP catalysts with high efficiency derived from heterogonous deposition-precipitation (HDP) against prepared catalysts by combined method (IMP-DP).
    The support and catalyst properties were determined by X-ray powder diffractometer (XRD), a field-emission scanning electron microscope (FESEM) and Brunauer-Emmett-Teller (BET) surface area measurements. Characterization analyses indicated that two different copper crystallites were formed (small and large) on the support as a consequence of using the combined catalyst preparation method. XRD and FESEM results showed that the prepared nano-catalysts had particle sizes of less than 30 nm where calculated removal efficiency was up 0.99 for oxidation of toluene
  9. Keywords:
  10. Toluene ; Catalytic Oxidation ; Metal Oxides ; Gama-Alumina

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