Dong Yujung, Zaera Francisco
Department of Chemistry and UCR Center for Catalysis , University of California , Riverside , California 92521 , United States.
J Phys Chem Lett. 2018 Mar 15;9(6):1301-1306. doi: 10.1021/acs.jpclett.8b00173. Epub 2018 Mar 2.
A high-flux molecular beam setup has been used to characterize the kinetics of the steady-state catalytic hydrogenation of unsaturated aldehydes, specifically of crotonaldehyde, promoted by platinum surfaces under single-collision conditions. Surprisingly, in addition to the hydrogenation of the individual single bonds, to yield the saturated aldehyde and the unsaturated alcohol, the formation of the saturated alcohol, the product of the hydrogenation of both C═C and C═O bonds, was detected as well. This indicates that the dual hydrogenation reaction is a primary pathway and not the result of secondary hydrogenation of the other products as commonly assumed. Moreover, an increase in the partial pressure of the reactant was found to shift the reaction selectivity from the saturated alcohol to the saturated aldehyde without significantly affecting the selectivity toward the production of the unsaturated alcohol. We explain these observations by proposing a mechanism involving the parallel formation of several monohydrogenated intermediates on the surface.
一种高通量分子束装置已被用于表征在单碰撞条件下由铂表面促进的不饱和醛（特别是巴豆醛）稳态催化氢化反应的动力学。令人惊讶的是，除了单个单键的氢化反应生成饱和醛和不饱和醇外，还检测到了饱和醇的形成，饱和醇是碳碳双键和碳氧双键都氢化的产物。这表明双氢化反应是主要途径，而不是如通常所认为的那样是其他产物二次氢化的结果。此外，发现反应物分压的增加会使反应选择性从饱和醇转向饱和醛，而不会显著影响生成不饱和醇的选择性。我们通过提出一种涉及表面上几种单氢化中间体平行形成的机制来解释这些观察结果。
