Liao Guan-Jr, Liu Kuan-Ting, Liao Zhen-He, Hsu Po-Wei, Wang Jeng-Han, Luo Meng-Fan
Department of Physics, National Central University, 300 Jhongda Road, Jhongli District, Taoyuan 32001, Taiwan.
Department of Chemistry, National Taiwan Normal University, No. 88, Sec. 4, Ting-Zhou Road, Taipei 11677, Taiwan.
J Phys Chem Lett. 2021 Mar 18;12(10):2622-2629. doi: 10.1021/acs.jpclett.1c00634. Epub 2021 Mar 10.
The size effect on the activity of a catalyst has been a focal issue since ideal catalysts were pursued, whereas that on the degradation of a catalyst, by reaction intermediates such as CO, is little discussed. We demonstrate that the dehydrogenation of methanol- on supported Rh nanoclusters precovered with CO (Rh clusters) was obstructed, indicated by a decreased production of CO and D; the obstructive effect exhibits a remarkable dependence on the cluster size, with a minimum at a cluster diameter near 1.4 nm. The decreased production arose from a decreased reaction probability controlled by the increased activation energy for each dehydrogenation step (including formation of methoxy-), adsorption energies of CO, and repulsion from the CO array on the Rh surface. The effects of these factors in deactivating the clusters varied separately with the cluster size. Consequently, the size effect on the CO poisoning should be taken into account in engineering the cluster size to optimize the catalytic performance.
