The investigation of selective carbon monoxide oxidation kinetics over the silver, cobalt oxide, manganese oxide doped cerium oxide / zirconium oxide included catalysts

In this study the synthesis, characterization and catalytic activity to the selective CO oxidation reaction were made over the Ag/CeO2/ZrO2 Co3O4/CeO2/ZrO2, MnO2/CeO2/ZrO2 nanocatalysts. All catalysts were prepared by the co-precipitation method and calcined at 450oC. The characteristic properties of the catalysts were determined by using the X-ray diffraction pattern, N2-physisorption measurements and scanning electron microscopy (SEM).According to the X-Ray diffraction patterns the CeZrOx, MnCeZrOx, metallic Ag and Co3O4 phases was obtained from the catalysts. The highest surface area was obtained from the MnO2/CeO2/ZrO2 catalyst and the lowest surface area was obtained from the Ag/CeO2/ZrO2 catalyst. Between the Co3O4/CeO2/ZrO2 catalysts which were prepared at different molar ratios, the catalysts has 20/40/40 molar ratio gave the highest surface area. All catalysts gave the average pore diameter in the mesopore diameter scale. The catalytic activities of the catalysts were determined for the selective CO oxidation reaction in H2 rich gas stream in which the compositions are 85% H2, 1% CO and %O2: 1.25, 1.5, 1.75 and; 85% H2, 2%O2 % 2 and CO: 0.75%, 1.00%, 1.15%, 1.30% balance with He on three different catalyst masses (15 mg, 25 mg, 35 mg). The best activity for the selective CO oxidation reaction was obtained from the 50/25/25Co3O4/CeO2/ZrO2 catalyst. The 50/25/25 Co3O4/CeO2/ZrO2 catalyst gave 90% CO conversion at 200oC and 55% selectivity to CO oxidation at 175oC. The best activity was obtained from the 50/10/10 Co3O4/CeO2/ZrO2 catalyst between the Co3O4/CeO2/ZrO2 catalysts which were prepared at different molar ratio. The 80/10/10 Co3O4/CeO2/ZrO2 catalyst gave 80% CO conversion at 200oC and 84% selectivity to CO oxidation at 125oC. The rate of selective CO oxidation reaction on 80/10/10 Co3O4/CeO2/ZrO2 catalyst is depend on O2 (+1.04) and CO (-1.4), the reaction coefficient is found as k = 1.64 x 10-4 .