Gold Size Effect in the Thermal-Induced Reaction of CO₂ and H₂ on Titania- and Titanate Nanotube-Supported Gold Catalysts

In this paper, we study the thermal activation of CO₂ on the surface of small Au nanoparticles supported on TiO₂ and titanate nanotube. We characterize the catalysts with high resolution transmission electron microscopy (HR-TEM) and total gold content measurement. We performed catalytic test in flow reactors then we investigate the surface of the catalysts during the adsorption and reaction processes by diffuse reflectance infrared spectroscopy (DRIFTS). The size of gold nanoparticles on the surface has been found to have the most important effect on the final activity of the studied catalysts. Significantly higher TOF values were obtained when the size of Au were smaller on both TiO₂ and titanate nanotube supports. The size of the Au nanoparticles with the method of their preparation was controlled. The gold adatom promotes the adsorption and scission of CO₂, but the nature of the support has got important effect, too. The explored reaction schemes may pave the way towards novel catalytic materials that can solve challenges associated with the activation of CO₂ and thus contribute to a greener chemistry related to it.