Preparation, performances and reaction mechanism for the synthesis of H2O2 from H2 and O2 based on palladium membranes

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New Pd-Pt and Pd-Au catalysts for an efficient synthesis of H2O2 from H2 and O2 under very mild conditions

Bimetallic Pd-Pt and Pd-Au samples supported on sulfated zirconia were successfully tested for the direct synthesis of hydrogen peroxide under very mild conditions (I bar and 293 K) and outside the explosion range. The effect of the addition of Pt to Pd in enhancing the yield of hydrogen peroxide is sensitive to the Pt amount: only using a low Pt content it is possible to improve H2O2 selectivity (from 55% to 70%) and productivity with respect to the monometallic sample. The addition of gold in 1:1 amount to palladium improved both the productivity and even more the selectivity of the process, producing a hydrogen peroxide concentration already useful for industrial applications and maintaining a stable selectivity (62%) after 12 h of time on stream

Pd-Fe/SiO2 Catalysts in the Hydrogenation of 2,4-Dinitrotoluene

Pd-Fe/SiO2 bimetallic catalysts with a constant amount of Pd and a different Fe/Pd ratio were prepared by sequential wet mpregnation and the hydrogenation of 2,4-dinitrotoluene was arried out at 25'C in a batch reactor. The presence of Fe nhances the Pd catalytic activity. The formation of a disperse Pd-Fe alloy was evidenced through X-ray powder diffraction nd is consistent with the data observed by FTIR analysis, TPR, nd chemisorption features. The increase of the Fe total conten f the catalysts results in the increase of the dispersion of the metallic phase and in the presence of partially oxidized Fe pecies. FTIR analysis shows that nitrocompounds chemisorb mainly on the support rather than on the metal surface. It is uggested that the Pd-Fe alloy formation is responsible for the ncrease of the catalytic activity because of a cooperative effect of Fe in the hydrogen transfer step

Transition metal catalysis in the Baeyer-Villiger oxidation of ketones

ANGEW. CHEM. INT. ED