A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-co...A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-containing catalysts were lower than those of the K-free ones, particularly for catalysts with high Pt contents （51.6 k）/mol for 0.42K-2.0Pt/Al2O3 and 6：3.6 kJ/mol for 2.0Pt/Al2O3 ）. The CO reaction orders were higher for the K-containing catalysts （about -0.2） than for the K-free ones （about -0.5）, with the former having much lower equilibrium constants for CO adsorption than the latter. In situ Fourier-transform infrared spectroscopy showed that surface CO desorption from the 0.42K-2.0Pt/Al2O3 catalyst was easier than from 2.0Pt/Al2O3. The promoting effect of K was therefore caused by weakening of the interactions between CO and surface Pt atoms. This decreased coverage of the catalyst with CO and facilitated competitive O2 chemisorption on the Pt surface, and significantly lowered the reaction barrier between chemisorbed CO and O2 species.展开更多
A simple and highly efficient protocol has been developed for the Pd/C-catalyzed ligand-free Suzuki- Miyaura reaction of potassium aryltrifluoroborates. In this catalytic system, the results demonstrate that oxygen pl...A simple and highly efficient protocol has been developed for the Pd/C-catalyzed ligand-free Suzuki- Miyaura reaction of potassium aryltrifluoroborates. In this catalytic system, the results demonstrate that oxygen plays a positive role in the cross-coupling reaction. In addition, this catalytic system could be successfully applied to synthesize biaryl compounds containing a carbazole moiety and the catalyst was recycled seven times without significant loss of catalytic activitv.展开更多
基金financially supported by the National Natural Science Foundation of China(21173195)~~
文摘A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-containing catalysts were lower than those of the K-free ones, particularly for catalysts with high Pt contents （51.6 k）/mol for 0.42K-2.0Pt/Al2O3 and 6：3.6 kJ/mol for 2.0Pt/Al2O3 ）. The CO reaction orders were higher for the K-containing catalysts （about -0.2） than for the K-free ones （about -0.5）, with the former having much lower equilibrium constants for CO adsorption than the latter. In situ Fourier-transform infrared spectroscopy showed that surface CO desorption from the 0.42K-2.0Pt/Al2O3 catalyst was easier than from 2.0Pt/Al2O3. The promoting effect of K was therefore caused by weakening of the interactions between CO and surface Pt atoms. This decreased coverage of the catalyst with CO and facilitated competitive O2 chemisorption on the Pt surface, and significantly lowered the reaction barrier between chemisorbed CO and O2 species.
基金financial support from the Nationa Natural Science Foundation of China (Nos. 21276043, 21421005)the Research Foundation of Dalian University of Technology for Retired Professors (No. DUTTX2015102)
文摘A simple and highly efficient protocol has been developed for the Pd/C-catalyzed ligand-free Suzuki- Miyaura reaction of potassium aryltrifluoroborates. In this catalytic system, the results demonstrate that oxygen plays a positive role in the cross-coupling reaction. In addition, this catalytic system could be successfully applied to synthesize biaryl compounds containing a carbazole moiety and the catalyst was recycled seven times without significant loss of catalytic activitv.
