In this work we designed a material based on CeOx-ZnO porous nanorods (NR) decorated with Au nanoparticles (NP) aiming to address two usually observed faults for oxide/noble metal materials applied in WGSR: noble metal nanoparticles of Au, Pd, Pt among others undergo sintering during catalysis, decreasing the catalytic performance, and also the formation undesired side products such as CH4 and CH3OH. First, CeO2 porous nanorods were synthesized through a robust hydrothermal method which yields nanorods known to have an internal porous structure with pores of the order of 1 nm, which were exposed and enlarged through brand acid leaching. These pores would then serve as host sites for the growth of Au NP. On previous works it was observed that ZnO could prevent the formation of the mentioned side products through stabilization of reaction intermediaries that lead to the proper products. Through the method of impregnation-decomposition cycles (IDC) we synthesized a ZnO coating over the leached CeOx NR, and the CeOx-ZnO porous NR was then used as host for the growth of Au NP, resulting in a structural design that exploits ZnO properties and optimizes the CeOx NR porous structure to better host Au NPs of small size (&lt;5 nm) and prevent their sintering during catalysis. The material construction was accompanied by high resolution transmission and scanning transmission electron microscopy, and the CeOx NR decorated with Au NP has shown activity at temperatures as low as 150 °C, but suffered a decrease in performance over time attributed to Au NP sintering, observed by an increase in average size from 2.5±0.9 to 4.0±1.0 nm. The inclusion of ZnO both prevents the growth of Au NP, resulting in ideally smaller NP for WGSR (1.8±0.4 nm compared to the previous 2.5±0.9 nm), and prevents their growth during catalysis, resulting in stable catalytic activity, coming only with the downside of lower catalytic performance for lower temperatures.

CeOx and CeOx-ZnO porous nanorods decorated with Au nanoparticles for the water-gas shift reaction (WGSR)

2019 Spring National Meeting

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