Evidence for and mitigation of the encapsulation of gold nanoparticles within silica supports upon high-temperature treatment of Au/SiO2 catalysts: Implication to catalyst deactivation

摘要: Abstract Silica is one of the most widely used catalyst supports for metal nanocatalysts. Although sintering nanoparticles on various silica has been extensively studied, restructuring and its effect supported have seldom investigated. In this paper, silica-supported gold catalysts were as a model system to probe interplay under high-temperature treatment conditions. Gold was loaded onto mesoporous SiO 2 (SBA-15) using Au(en) Cl 3 precursor in presence aqueous NaOH (pH ∼ 10). The influence textural structural changes SBA-15 Au/SBA-15 studied by X-ray diffraction (XRD), N adsorption–desorption, transmission electron microscopy (TEM). Control experiments conducted an amorphous (Cab-O-Sil) support. It found that undergoes significant phase transformation crystalline cristobalite upon treatment, resulting dramatic decrease surface area. More interestingly, crystallization leads encapsulation inside matrix. This conclusion proven aqua regia leaching, EDX, SEM/TEM experiments. can also be encapsulated into matrix when Cab-O-Sil support, but process takes place much higher temperatures. mitigated coating with Al O or before loading gold. Our findings shed new light deactivation