Effect of Electrolyte Composition and Mass Transport on Electrochemical Hydrogenations of a Terminal Alkynol

Electrochemical hydrogenations (EChH) constitute a sustainable alternative to conventional thermocatalytic hydrogenation. Here, we explored the EChH of the vitamin E and A synthon 2-methyl-3-butyn-2-ol in a scalable zero-gap electrolyzer and revealed crucial effects of electrolyte composition and convection parameters to consider for optimization. We show that high Faraday efficiencies can be achieved with low to moderate concentrations of neutral or alkaline electrolytes. While the flow rate has a strong impact on performance, electrode compression and cell orientation can be used for fine tuning. We achieved a Faraday efficiency of up to 69 % for the targeted semi-hydrogenated product at current densities of 80 mA cm-2 at 2.2 V cell voltage and a concentration of 1 M 2-methyl-3-butyn-2-ol. The electrochemical hydrogenation of the vitamin A and E synthon 2-methyl-3-butyne-2-ol with a noble metal-free pentlandite catalyst was conducted in a scalable zero-gap electrolyzer. Electrolyte composition and transport parameters were investigated to elucidate their role in the performance of the electrolysis. image