Abstract:The subject of the investigation was the model solution containing 50 g/dm³ waste light ends from PVC production, dissolved in the ethanol-water (1:1) mixture. The main components of light ends were as follows: trichloromethane, tetrachloromethane, and chloroderivatives of ethane. Granular ferric-chromic catalyst (TZC 3/1) was used in the investigation. The temperature range applied in experiments was 400-600ºC and the contact time was 0.27 s. Gaseous products of the reaction were analysed in order to determine among others concentration of chlorine, formaldehyde, oxygen, carbon monoxide and dioxins. The content of total organic carbon (TOC), chloride ions and formaldehyde was determined in a condensate. Oxidation of the mixture proceeded in the all temperature range with high efficiency in regard to initial TOC value of the solution. The concentration of dioxins in the combustion gases obtained in the process carried out in temperature 450ºC amounted to 0.021-0.027 ng TEQ/m 3 , and was significantly lower than the admissible value of 0.1 ng TEQ/m 3 . Congeners of polychlorinated dibenzofuranes (PCDFs) predominated in the combustion gases. Tested catalyst did not undergo deactivation during 150 h substrate oxidation.
Tetrachloromethane (TCM) and 1,1,2,2-tetrachloroethane (TChE) were oxidized in the temperature range from 300 to 600°C and at contact time of 0.36 s. The following catalysts were applied during the process: the granular one-platinum (0.12%) at the TiO 2-SiO 2 carrier, platinum ZChO-80 (0.15%) at γ-Al 2 O 3 carrier, palladium (1%) at γ-Al 2 O 3 carrier and monolithic platinum-rhodium catalyst (Pt-0.09% and Rh-0.04%) at the cordierite carrier. The substrates were oxidized in the presence of the above mentioned catalysts with various efficiencies depending on the molecular structure and the type of the catalyst. Palladium contact appeared to be the most active among the others. In the presence of this catalyst, total oxidation of TCM and TChE proceeded at the temperature of 425 and 500°C, respectively. The content of PCDD/Fs in gaseous products obtained during the oxidation of both substrates, was significantly lower than the admissible value of the toxicity equivalent (0.1 ng TEQ/m 3).
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