Abstract
Pd catalysts supported on silica were tested for H2O2 direct synthesis under very mild (1bar, 20°C, no halide addition) and nonexplosive conditions. Other catalytic tests were performed at higher pressure using a solvent expanded with CO2. The optimum Pd content is 1.5wt.%. Calcination is mandatory to preserve catalytic performance and recycle the catalyst. A comparison among Pd samples with similar metal content over different supports was performed under identical experimental conditions, showing that Pd/SiO2 gives the highest selectivity (constant at 60%). At the same time, the productivity follows the trend: Pd/SiO2>Pd/ZrO2/SO4=>Pd/ZrO2>Pd/CeO2/SO4=>Pd/CeO2. HRTEM and chemisorption results clearly indicate that a high Pd dispersion is not advisable to observe good catalytic performance. On the contrary, the presence of less energetic Pd sites exposed at the surface of big particles of Pd/SiO2, where oxygen can chemisorb without dissociation, is a necessary condition to produce H2O2.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.