화학공학소재연구정보센터
Applied Surface Science, Vol.308, 230-236, 2014
Insight into the effects of different ageing protocols on Rh/Al2O3 catalyst
In this work, a catalyst of Rh loaded on Al2O3 was prepared by impregnating method with rhodium nitrate aqueous solution as the Rh precursor. The catalyst was aged under different protocols (lean, rich, inert and cyclic) to obtain several aged samples. All the Rh/Al2O3 samples were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, CO-chemisorption, H-2-temperature programmed reduction (H-2-TPR), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). It was found that a specific ageing treatment could strongly affect the catalytic activity. The N-2 aged and the H-2 aged samples had a better catalytic activity for CO + NO reaction than the fresh sample while the air aged and the cyclic aged samples exhibited much worse activity. More surface Rh content and better reducibility were obtained in the N-2 and the H-2 aged samples and the Rh particles existed with an appropriate size, which were all favorable to the catalytic reaction. However, the air and the cyclic ageing protocols induced a strong interaction between Rh species and the Al2O3 support, which resulted in a severe sintering of particles of Rh species and the loss of active sites. The structure evolution scheme of the catalysts aged in different protocols was also established in this paper. (C) 2014 Elsevier B.V. All rights reserved.