Effect of Zirconium Precursor on Performance of Pd/Ce0.45Zr0.45La0.1O1.95 Three-Way Catalyst

Three types of Ce0.45Zr0.45La0.1O1.95 mixed oxides were prepared by H2O2-assisted precipitation using ZrOCO3, ZrO(NO3)2, and Zr(NO3)4 as precursors. The Pd/Ce0.45Zr0.45La0.1O1.95 three-way catalysts were prepared by the wet impregnation and characterized by X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and oxygen storage capacity. XRD and Raman results showed that the use of ZrOCO3 or ZrO(NO3)2 gave a CeO2-ZrO2 mixed oxide with a cubic phase of high thermal stability, while an extra t″-phase was observed in the aged Pd/Ce0.45Zr0.45La0.1O1.95 catalyst prepared using Zr(NO3)4. The activities of the three catalysts were evaluated using simulated exhaust gas under working conditions. The Pd/Ce0.45Zr0.45La0.1O1.95 catalyst prepared using ZrOCO3 as precursor gave the best activities for C3H8, CO, and NO conversion. The use of ZrOCO3 as precursor was better suited for the formation of Ce3+ and more favorable for the homogeneous insertion of Zr4+ and La3+ into the CeO2 lattice, which resulted in better thermal stability and enhanced redox properties of the Pd/Ce0.45Zr0.45La0.1O1.95 catalyst.

摘要报道了温和条件下甘油和碳酸二甲酯在一系列碱性催化剂作用下合成碳酸甘油酯的活性规律和构效关系. 结果表明, 在所选择的催化剂中, NaY 分子筛对目标反应具有较高的活性和最高的目的产物选择性; 另外, 甘油和碳酸二甲酯的反应对催化剂的孔道结构具有特殊的要求, 3A, 4A 和 NaZSM-5 等孔径较小 (< 0.6 nm) 的分子筛没有催化活性, 而孔径较大的 NaY 和 Naβ 则表现出较高的催化活性.

Graphical abstractThe use of ZrOCO3 gave a pure fluorite structure with better insertion of Zr4+ and La3+ into the CeO2 lattice, and Pd supported on it gave superior three-way catalyst performance.Figure optionsDownload full-size imageDownload as PowerPoint slide