Liao Weisheng, Pan Horng-Bin, Liu Hsin-Wang, Chen Hsing-Jung, Wai Chien M
Department of Chemistry, University of Idaho, Moscow, Idaho 83844, USA.
J Phys Chem A. 2009 Sep 10;113(36):9772-8. doi: 10.1021/jp9008459.
Hydrodechlorination of 4-chlorobiphenyl in supercritical fluid carbon dioxide (SF-CO(2)) catalyzed by palladium nanoparticles stabilized in high-density polyethylene beads proceeds by consecutive reactions to the final product bicyclohexyl. Each step of the reaction sequence, that is, 4-chlorobiphenyl --> biphenyl --> cyclohexylbenzene --> bicyclohexyl, follows pseudo-first-order kinetics. Arrhenius parameters of each reaction step were determined separately in SF-CO(2) by in situ absorption spectroscopy using a high-pressure fiber-optic cell. A simulation of product distributions using the first-order consecutive reaction equations was performed and compared with the experimental results obtained by GC/MS analysis of the 4-chlorobiphenyl reaction system. The differences are explained in terms of adsorption/desorption behavior of the intermediates on the catalytic metal surface with respect to the stereostructures of the molecules generated by a molecular mechanics method.
在由稳定于高密度聚乙烯珠粒中的钯纳米颗粒催化的超临界流体二氧化碳（SF-CO₂）中，4-氯联苯的加氢脱氯通过连续反应生成最终产物双环己基。反应序列的每一步，即4-氯联苯→联苯→环己基苯→双环己基，均遵循准一级动力学。通过使用高压光纤池的原位吸收光谱法在SF-CO₂中分别测定了每个反应步骤的阿伦尼乌斯参数。使用一级连续反应方程对产物分布进行了模拟，并与通过对4-氯联苯反应体系进行GC/MS分析获得的实验结果进行了比较。根据分子力学方法生成的分子立体结构，就中间体在催化金属表面上的吸附/解吸行为对差异进行了解释。
