钯-路易斯酸体系催化苯酚选择性加氢生成环己酮

Selective Phenol Hydrogenation to Cyclohexanone over a Dual Supported Pd-Lewis Acid Catalyst

环己酮是一个重要的合成尼龙等材料的中间体,可通过苯酚加氢反应制备,但该反应过程的效率受到环己酮进一步加氢生成副产物环己醇的制约。本项研究表明,普通的商业负载型钯催化剂(负载在碳、氧化铝或NaY沸石上)和路易斯酸(如AlCl3)可协同促进苯酚加氢生成环己酮的反应。在适当条件下,苯酚转化率和环己酮选择性可同时接近100%。路易斯酸不仅促进苯酚加氢生成环己酮的反应,而且可有效地抑制产物环己酮被进一步加氢生成副产物的反应。在超临界CO2中反应效率还可大幅度提高。

Cyclohexanone is an industrially important intermediate in the synthesis of materials such as nylon,but preparing it efficiently through direct hydrogenation of phenol is hindered by over-reduction to cyclohexanol.Our study showed that combination of nanoparticulate palladium（supported on carbon,alumina,or NaY zeolite）and a Lewis acid such as AlCl3synergistically promotes this reaction.Conversion and selectivity could approach 100% simultaneously at suitable conditions.Preliminary kinetic and spectroscopic studies suggest that the Lewis acid sequentially enhances the hydrogenation of phenol to cyclohexanone and then inhibits further hydrogenation of the ketone.Higher reaction efficiency was achieved in compressed CO2 solvent medium.