Synthesis and properties of CuO/Zeolite sandwich type adsorbent-catalysts

The CuO/zeolite sandwich type adsorbent-catalysts were prepared by wet impregnation of parent synthetic zeolites (NaA, CaA, NaX, and CaX) with copper(II ) nitrate water solution (50.0 g/L) for 2 h, followed by drying for 1 h and calcination at 450 degrees C for 6 h. Composed coatings of active component (CuO) oil parent zeolites are about I mm. The parent zeolites, impregnated media, and adsorbent-catalysts were characterized by atomic absorption spectroscopy, X-ray diffraction, infrared spectroscopy, and differential scanning calorimetry. The adsorbent-catalysts were used for catalytic oxidation of alcohol (methanol, I-propanol, and 1-butanol) vapor, and the catalytic activity tests were carried out in a fixed-bed quartz reactor in the 100-350 degrees C range. The by-products and their concentration in the feed stream of air were determined. The maximum quantities of by-products were formed in the range of 220-250 degrees C. The lifetime of the CuO/zeolite catalysts for the oxidation of alcohols was about 4 months. At this time, sandwich-type catalysts were active for the oxidation of alcohols into CO2 and H2O in the range of 100-350 degrees C. With increasing molecular weight of alcohols and decreasing their initial concentration in the feed stream, the temperatures of light-off and total oxidation to CO2 and H2O decreased.