Ammonia Oxidation Process Catalyzed by Pt@XO2 (X = Ti, Zr, Ce, and Ce/Zr) Prepared by Photoreduction Process
2018
Liu, Qiang | Pu, Xueling | Yue, Hairong | Jiang, Wei | Liang, Bin
In the nitric acid industry, platinum loss is the second largest cost due to vaporization of the Pt gauze catalyst at high temperature. In this research, Pt is loaded on TiO₂, ZrO₂, CeO₂, and ceria–zirconia solid solution by photoreduction and used as catalysts for ammonia oxidation. Results show that Pt content of the obtained catalysts is effectively reduced to 0.08 wt %, but their catalytic performance is better than that of the traditional Pt gauze between 300 and 800 °C. The best catalyst, 3Pt@CeO₂ with 0.0797 wt % Pt content, enabled complete ammonia transformation at 300 °C and 80% NOₓ yield at 800 °C with the space velocity of 235 000 h–¹ and the oxygen-to-ammonia ratio of 15 in ambient pressure. After 50 h of continuous operation, no observable decay in performance was detected. Such excellent performance is ascribed to the lattice oxygen provided by CeO₂ and the formation of Pt–Ce–O. These results provide a promising method of improving the current industrial Pt catalysts.
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