Chu Shasha, Cai Zhengmiao, Wang Mingzhi, Zheng Yanping, Wang Yongke, Zhou Zhaohui, Weng Weizheng
State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of Alcohols, Ethers and Esters, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China.
Nanoscale. 2020 Oct 22;12(40):20922-20932. doi: 10.1039/d0nr04644b.
γ-Al2O3 nanosheet supported rhodium catalysts with Rh loadings between 0.05 and 2 wt% were prepared by the impregnation method and used for dry reforming of methane (DRM). It was found that Rh species on γ-Al2O3 nanosheets demonstrated excellent stability against sintering at high temperature. After calcining in air at 800 °C followed by reducing with hydrogen at 600 °C, the average particle size of Rh at maximum distribution increases from 1.0 ± 0.3 to 1.8 ± 0.3 nm with an increase in Rh loadings in the catalysts from 0.05 to 2 wt%. Even after reducing with hydrogen at 900 °C, the average size of Rh particles in the catalysts still remained below 2 nm. The results of catalytic performance evaluation show that CH4 and CO2 conversions of 84% and 90%, respectively, with a H2/CO ratio in syngas close to unity can be achieved with a catalyst of Rh loading of only 0.05 wt% at 750 °C. The performance of the catalyst remains stable for more than 200 h. No significant aggregation of the Rh particles is observed on the catalyst after the reaction. The results of XPS, H2-TPR and O2-TPD characterization methods indicate that the strong interaction between Rh and the γ-Al2O3 nanosheets plays a key role in increasing the dispersion of Rh species in the catalyst and preventing it from sintering under high temperature conditions. This factor is also responsible for the superior activity and stability of the catalyst with extremely low Rh loading for the DRM reaction.
采用浸渍法制备了铑负载量在0.05%至2 wt%之间的γ-Al2O3纳米片负载铑催化剂，并将其用于甲烷干重整（DRM）反应。研究发现，γ-Al2O3纳米片上的铑物种在高温下表现出优异的抗烧结稳定性。在800℃空气中煅烧，随后在600℃用氢气还原后，随着催化剂中铑负载量从0.05 wt%增加到2 wt%，最大分布处铑的平均粒径从1.0±0.3 nm增加到1.8±0.3 nm。即使在900℃用氢气还原后，催化剂中铑颗粒的平均尺寸仍保持在2 nm以下。催化性能评价结果表明，在750℃下，仅含0.05 wt%铑负载量的催化剂可实现CH4和CO2转化率分别为84%和90%，合成气中的H2/CO比接近1。催化剂性能在200 h以上保持稳定。反应后催化剂上未观察到铑颗粒的明显聚集。XPS、H2-TPR和O2-TPD表征方法的结果表明，铑与γ-Al2O3纳米片之间的强相互作用在增加催化剂中铑物种的分散度以及防止其在高温条件下烧结方面起着关键作用。这一因素也是该极低铑负载量催化剂在DRM反应中具有优异活性和稳定性的原因。
