The aerobic oxidation of methanol and ethanol in liquid phase is investigated using unsupported nanoporous gold (npAu) catalysts and compared to gas phase experiments. We pursue the question if this material is still suited as a type of model catalyst even under much more complex conditions in liquid phase. Indeed, npAu is an active catalyst for both liquid and gas phase oxidation of methanol and ethanol with O₂ under mild conditions (starting at 40 °C). While in case of methanol solely the self coupling product (methyl formate) is detected, the more facile formation of the acetaldehyde in case of ethanol results in the formation of the free aldehyde (acetaldehyde) and the coupling product (ethyl acetate) in similar amounts. To further probe the surface chemistry, cross coupling reactions between both alcohols, as well as the acetaldehyde are performed. As observed also in gas phase experiments, the formation of the surface bonded aldehyde by β-H elimination of the alcoxy species is rate determining.

使用无载体的纳米多孔金（npAu）催化剂研究了甲醇和乙醇在液相中的好氧氧化，并与气相实验进行了比较。我们追问的问题是，即使在液相中更为复杂的条件下，这种材料是否仍适合用作模型催化剂。实际上，npAu是用于O ₂催化甲醇和乙醇液相和气相氧化的活性催化剂在温和的条件下（从40°C开始）。在仅使用甲醇的情况下，仅检测到自偶联产物（甲酸甲酯），而在使用乙醇的情况下，更容易形成乙醛，导致游离醛（乙醛）和偶联产物（乙酸乙酯）的形成量相似。 。为了进一步探究表面化学性质，在两种醇以及乙醛之间进行了交叉偶联反应。如在气相实验中还观察到的，通过β-H消除烷氧基物种而形成的表面键合醛是决定速率的。