Fan Kangnian

Modification effect of Pd and Pt on Ru/ZrO 2 catalyst for partial hydrogenation of benzene to cyclohexene

We report the modification effects of Pd and Pt on the partial hydrogenation of benzene to cyclohexene over the Ru/ZrO2 catalyst. The Ru/ZrO2, Ru-Pd/ZrO2 and Ru-Pt/ZrO2 catalysts were prepared by the wetness impregnation-chemical reduction method at room temperature. The catalysts were characterized by N2 physisorption, H2 chemisorption, powder X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), transmission electron microscopy (TEM), X-ray absorption spectroscopy (XAS), and differential scanning calorimetry (DSC). It was identified that the Ru-Pd and Ru-Pt alloys were formed on the Ru-Pd/ZrO2 and Ru-Pt/ZrO2 catalysts, which improved the coordination number of Ru. In the partial hydrogenation of benzene to cyclohexene, while the modification of the Ru/ZrO2 catalyst with Pd or Pt decreased the turnover frequency (TOF) of benzene, the initial selectivity ( S 0) to cyclohexene was improved. The Ru-Pd/ZrO2-0.2 and Ru-Pt/ZrO2-0.15 catalysts with the optimal Pd/Ru and Pt/Ru molar ratios of 0.2 and 0.15 exhibited similar S 0 and the yield of cyclohexene of about 77% and 44%, respectively. On the basis of the characterization results, the modification effects of Pd and Pt on the activity and selectivity of the Ru/ZrO2 catalyst were discussed.

A Theoretical Distinction Between Time-Resolved Resonance Raman and Resonance Fluorescence

Based on the time-dependent theory, an analysis of the distinction between resonance Raman (RR) and resonance fluorescence (RF) with pulse excitation was presented. The real population of the intermediate state gives two optical components-the independent time evolution of intermediate ket and bra states generates RR while RF originates from the phase coherent between ket and bra states. In cw limit, the transition probability of spontaneous emission with pulse excitation can be reduced to the classical theory.

DYNAMICAL THEORY OF SPECTROSCOPY WITH FEMTOSECOND PULSE EXCITATION(III) : TRANSIENT RATE EQUATION IN LIOUVILLE SPACE

A dynamical theory of spectroscopy with femtosecond pulse excitation is developed in Liouville space. By using density matrix formalism, the transient rate equation that can be reduced to the classical KHD expression in CW case is obtained. This theory is applied to the Raman excitation profile of IBr and the results are in agreement with the experiments.A dynamical theory of spectroscopy with femtosecond pulse excitation is developed in Liouville space. By using density matrix formalism, the transient rate equation that can be reduced to the classical KHD expression in CW case is obtained. This theory is applied to the Raman excitation profile of IBr and the results are in agreement with the experiments.