Selective formation of lactate by oxidation of 1,2-propanediol using gold palladium alloy supported nanocrystals
作者:Nikolaos Dimitratos、Jose Antonio Lopez-Sanchez、Sankar Meenakshisundaram、Jinto Manjaly Anthonykutty、Gemma Brett、Albert F. Carley、Stuart H. Taylor、David W. Knight、Graham J. Hutchings
DOI:10.1039/b823285g
日期:——
The use of bio-renewable resources, such as glycerol, a by-product from bio-diesel manufacture, can provide a viable way to make valuable products using greener technology. In particular, glycerol can be reduced to give 1,2-propanediol that can then be selectively oxidised to lactate, which has immense potential as a monomer for the synthesis of biodegradable polymers. We show that gold-palladium alloy catalysts can be very effective for the selective oxidation of 1,2-propanediol to lactate. Two supports, TiO2 and carbon, and two preparation methods, wet impregnation and sol-immobilisation, are contrasted. The addition of palladium to gold significantly enhances the activity and retains the high selectivity to lactate using O2 as oxidant (we observe 96% lactate selectivity at 94% conversion). Use of hydrogen peroxide is also possible but lower activities are observed as a result of the reaction conditions, but in this case no marked enhancement is observed on addition of palladium to gold. Comparison of the activity for C3 alcohols shows that the reactivity decreases in the order: glycerol > 1,2-propanediol > 1,3-propanediol ∼ 1-propanol > 2-propanol. The use of a sol-immobilisation preparation method as compared to impregnation leads to alloy catalysts with the highest activity for lactate formation from the oxidation of 1,2-propanediol; the origins of these activity trends are discussed.
使用生物可再生资源,例如甘油,这是一种生物柴油制造的副产品,可以提供一种利用更环保技术制造有价值产品的可行方法。特别是,甘油可以被还原为1,2-丙二醇,然后选择性氧化为乳酸,乳酸作为合成生物可降解聚合物的单体具有巨大潜力。我们展示了金-钯合金催化剂在1,2-丙二醇选择性氧化为乳酸方面的高效性。我们对比了两种载体(TiO2和碳)以及两种制备方法(湿法浸渍和溶胶固化)。将钯添加到金中显著提高了活性,并在使用O2作为氧化剂时保持了对乳酸的高选择性(我们观察到在94%转化率下乳酸选择性为96%)。虽然也可以使用过氧化氢,但由于反应条件,观察到活性较低,在这种情况下,添加钯到金中并未显著提高活性。对C3醇的活性比较表明,反应性按顺序降低:甘油 > 1,2-丙二醇 > 1,3-丙二醇 ∼ 1-丙醇 > 2-丙醇。与浸渍法相比,采用溶胶固化制备方法得到的合金催化剂在1,2-丙二醇氧化生成乳酸时具有最高的活性;这些活性趋势的来源进行了讨论。