Korobova Arina, Gromov Nikolay, Medvedeva Tatiana, Lisitsyn Alexander, Kibis Lidiya, Stonkus Olga, Sobolev Vladimir, Podyacheva Olga
Boreskov Institute of Catalysis SB RAS, Lavrentiev Av. 5, 630090 Novosibirsk, Russia.
Materials (Basel). 2023 Feb 9;16(4):1465. doi: 10.3390/ma16041465.
The catalysts with platinum-group metals on nanostructured carbons have been a very active field of research, but the studies were mainly limited to Pt and Pd. Here, Ru catalysts based on nitrogen-doped carbon nanotubes (N-CNTs) have been prepared and thoroughly characterized; Ru loading was kept constant (3 wt.%), while the degree of N-doping was varied (from 0 to 4.8 at.%) to evaluate its influence on the state of supported metal. Using the N-CNTs afforded ultrafine Ru particles (<2 nm) and allowed a portion of Ru to be stabilized in an atomic state. The presence of Ru single atoms in Ru/N-CNTs expectedly increased catalytic activity and selectivity in the formic acid decomposition (FAD) but had no effect in catalytic wet air oxidation (CWAO) of phenol, thus arguing against a key role of single-atom catalysis in the latter case. A remarkable difference between these two reactions was also found in regard to catalyst stability. In the course of FAD, no changes in the support or supported species or reaction rate were observed even at a high temperature (150 °C). In CWAO, although 100% conversions were still achievable in repeated runs, the oxidizing environment caused partial destruction of N-CNTs and progressive deactivation of the Ru surface by carbonaceous deposits. These findings add important new knowledge about the properties and applicability of Ru@C nanosystems.
负载铂族金属的纳米结构碳催化剂一直是一个非常活跃的研究领域，但研究主要局限于铂和钯。在此，制备并全面表征了基于氮掺杂碳纳米管（N-CNTs）的钌催化剂；钌负载量保持恒定（3 wt.%），同时改变氮掺杂程度（从0到4.8 at.%）以评估其对负载金属状态的影响。使用N-CNTs可得到超细钌颗粒（<2 nm），并使一部分钌以原子态稳定存在。Ru/N-CNTs中钌单原子的存在预期会提高甲酸分解（FAD）的催化活性和选择性，但对苯酚的催化湿式空气氧化（CWAO）没有影响，因此反对单原子催化在后者中起关键作用。在催化剂稳定性方面也发现了这两个反应之间的显著差异。在FAD过程中，即使在高温（150°C）下，也未观察到载体、负载物种或反应速率的变化。在CWAO中，尽管在重复运行中仍可实现100%的转化率，但氧化环境导致N-CNTs部分破坏，并且钌表面因碳质沉积物而逐渐失活。这些发现为Ru@C纳米系统的性质和适用性增添了重要的新知识。
