Effects of hydrothermal oxidation time of Al on the catalytic performance of Ru/Al@Al2O3 for selective oxidation of CO in H2

The thermal-conducting support is highly desirable for endothermic and exothermic reactions as long as highly dispersed active sites can be maintained. The core-shell Al@Al2O3 supports with different aluminum (Al) contents were prepared from Al particle by controlling the reaction time during hydrothermal surface oxidation and applied as a support to the supported Ru catalysts for preferential CO oxidation in H-2 (PROX). The prepared catalysts were characterized by N-2-physisorption, X-ray diffraction, CO chemisorption, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), in situ diffuse reflectance infrared Fourier transform spectroscopy after CO adsorption (CO-DRIFTS), and temperature-programmed desorption of ammonia (NH3-TPD) and ethanol (ethanol-TPD). The catalytic activity was dependent on the Al content in the Al@Al2O3 support. The most active Ru/Al@gamma-Al2O3 catalyst oxidized CO selectively in H-2 over a wide reaction temperature. The surface property of the outermost exterior alumina layer in the Al@gamma-Al2O3 support, determined with ethanol TPD, was beneficial for formation of Ru nanoparticles with weak adsorption of CO, probed with CO-DRIFTS, results in the high catalytic performance for PROX.

Automated summary

In this study, core-shell Al@Al2O3 supports with different Al contents were prepared and used for supporting Ru catalysts, revealing the significant impact of Al content on catalytic activity. The surface property of the outermost alumina layer in the support was found to be beneficial for the formation of Ru nanoparticles, leading to enhanced catalytic performance for PROX.