The hydrogenation of benzaldehyde in cyclohexane over a 5 wt% Pd/Al₂O₃ catalyst at 313 K is firstly investigated at ambient pressure in a stirred batch reactor. The formation of benzyl alcohol is a facile process and a small mass imbalance is indirectly attributed to the formation of benzene as a by-product. No hydrogenolysis reaction to form toluene is observed. Secondly, examination of this reaction system by attenuated total reflection infrared (ATR-IR) spectroscopy enables the chemistry at the liquid/solid interface to be probed. Specifically, the ν(C=O) modes of solvated and adsorbed benzaldehyde are evident at 1712 and 1691 cm⁻¹ respectively, providing information on how the reagent is partitioning within the reaction medium. Spectral acquisition on initiation of hydrogenation then enables the benzaldehyde → benzyl alcohol transition to be tracked. The additional presence of a broad CO stretching band of chemisorbed carbon monoxide (1852–1929 cm⁻¹) is attributed to the hydrogen-assisted decarbonylation pathway that forms the benzene by-product.

首先在环境温度下在搅拌的间歇反应器中研究在5 wt％Pd / Al ₂ O ₃催化剂上于313 K下苯甲醛在环己烷中的氢化。苯甲醇的形成是容易的过程，少量的质量失衡间接地归因于苯作为副产物的形成。没有观察到氢解反应形成甲苯。其次，通过衰减全反射红外（ATR-IR）光谱检查该反应系统，可以探测液/固界面的化学性质。具体而言，在1712和1691 cm ^-1处明显存在溶剂化和吸附的苯甲醛的ν（C = O）模式。分别提供有关试剂如何在反应介质中分配的信息。氢化开始后的光谱采集可以追踪苯甲醛→苯甲醇的转变。化学吸附的一氧化碳（1852-1929 cm ^-1）的宽CO拉伸带的额外存在归因于形成苯副产物的氢辅助脱羰途径。