Mekki Imene, Grzybek Gabriela, Kotarba Andrzej, García-García Avelina
Carbon Materials and Environment Research Group (MCMA), Department of Inorganic Chemistry and Institute of Materials, University of Alicante, Carretera de San Vicente del Raspeig, s/n, 03690 Alicante, Spain.
Faculty of Chemistry, Jagiellonian University in Kraków, Gronostajowa 2, 30-387 Krakow, Poland.
Nanomaterials (Basel). 2024 Mar 7;14(6):483. doi: 10.3390/nano14060483.
Soot combustion experiments with 5%O/He were conducted using model soot, and four distinct compositions of CePrO oxides of varying nominal cerium compositions (x = 0, 0.2, 0.3, and 1) were prepared. The catalyst samples were comprehensively characterized using techniques such as XRD, Raman spectroscopy, HR-TEM, N adsorption at -196 °C, XPS, O-TPD, H-TPR, and work function measurements. The Pr-rich compositions, ranging from CePrO to PrO, resulted in a significant increase in the total evolved O amounts and enhanced catalyst reducibility. However, a decrease in the textural properties of the catalysts was noted, which was particularly important for the pure praseodymia under the synthesis route conducted. The catalytic activity was investigated under the two following contact modes of mixing between soot and catalyst: and . The results revealed that the catalytic performance is associated with the surface contact in tight contact mode and with the combination of surface/subsurface/bulk oxygen mobility and the BET surface area in contact mode. Notably, the temperatures estimated at 10% and 50% of the conversion (T and T) parameters were achieved at much lower temperatures than the uncatalyzed soot combustion, even under contact conditions. Specifically, the 50% conversion was achieved at 511 °C and 538 °C for CePrO and CePrO, respectively. While no direct correlation between catalytic activity and work function was observed, a significant relationship emerges between work function values and the formation of oxygen vacancies, whatever the conditions used for these measurements. On the other hand, the ability to generate a high population of oxygen vacancies at low temperatures, rather than the direct activation of gas-phase O, influences the catalytic performance of Pr-doped ceria catalysts, highlighting the importance of surface/subsurface oxygen vacancy generation, which was the parameter that showed a better correlation with the catalytic activity, whatever the soot conversion value or the mode of contact considered.
使用模型炭黑进行了5%O₂/He气氛下的炭黑燃烧实验，并制备了四种不同标称铈组成（x = 0、0.2、0.3和1）的CePrO氧化物组合物。采用XRD、拉曼光谱、高分辨透射电子显微镜、-196℃下的N₂吸附、X射线光电子能谱、O₂程序升温脱附、H₂程序升温还原和功函数测量等技术对催化剂样品进行了全面表征。富含Pr的组合物，从CePrO到PrO，导致总释放氧量显著增加，并提高了催化剂的还原性。然而，注意到催化剂的织构性质有所下降，这对于所采用合成路线下的纯氧化镨尤为重要。在炭黑与催化剂的两种混合接触模式下研究了催化活性： 和 。结果表明，紧密接触模式下的催化性能与表面接触有关，而 接触模式下的催化性能与表面/次表面/体相氧迁移率和BET表面积的组合有关。值得注意的是，即使在 接触条件下，在10%和50%转化率（T₁₀%和T₅₀%）参数下估计的温度也比未催化的炭黑燃烧温度低得多。具体而言，CePrO和CePrO分别在511℃和538℃实现了50%的转化率。虽然未观察到催化活性与功函数之间的直接相关性，但无论用于这些测量的条件如何，功函数值与氧空位的形成之间都存在显著关系。另一方面，在低温下产生大量氧空位的能力，而不是气相O₂的直接活化，影响了Pr掺杂二氧化铈催化剂的催化性能，突出了表面/次表面氧空位产生的重要性，无论考虑的炭黑转化率值或接触模式如何，该参数与催化活性显示出更好的相关性。
