Effects of Organic Modifiers on a Palladium Catalyst in the Competitive Hydrogenation of 1-Octene Versus Octanal: An Evaluation of Solid Catalysts with an Ionic Liquid Layer

The competitive hydrogenation between 1-octene and octanal has been investigated with a ≈5% palladium on alumina catalyst prepared in situ with the following organic modifiers: pyridine, 1-methylimidazole, 1,3-dimethylimidazole methylsulfate, 1,3-dimethylimidazole bis(trifluoromethylsulfonyl)imide and methyltri-sec-butylphosphonium methylsulfate. The results of these investigations indicate that the ionic liquid modifiers have significant and specific effects on catalytic performance, for example, certain systems can completely suppress octanal conversion. In addition, analytical techniques reveal that the matrix and quantity of organic species on the used catalysts are different if different ionic liquids are used as modifiers. Surface studies also reveal that the modifiers have a noticeable effect on the crystallite size and chemisorption properties of the catalysts.