Deactivation mechanism of Pd supported on ordered and non-ordered mesoporous silica in the direct H2O2 synthesis using CO2-expanded methanol

摘要: Abstract The deactivation mechanism of Pd supported on silica and mesoporous (SBA-15) using CO 2 -expanded methanol as solvent was studied in the direct synthesis H O batch semi-continuous reactor tests well its hydrogenolysis. Fresh used catalysts were characterized by TPR chemisorption. results evidence presence deactivation, which can be correlated to loss accessible active metal surface area due sintering Pd, but there is also an effect ordered structure reaction conditions. higher concentration solution with respect leads a more relevant Pd-SiO Pd-SBA-15, initial activity, fact that accelerates reduction species are less reducible than Pd-SBA-15. Pd-SBA-15 shows selectivity productivity tests, related easier species. Another difference different sintering. On SBA-15 support, mesoporosity, particles migrate into channels forming elongated 1D-type particles. In catalyst, instead, large aggregates range 20–25 nm.