Electrocatalytic hydrogenation of alkenes with Pd/carbon nanotubes at an oil–water interface
Chenhui Han, Johannes Zenner, Jacob Johny, Nicolas Kaeffer, Alexis Bordet, Walter Leitner
Abstract
Abstract Electrocatalytic hydrogenation (ECH) produces high-value chemicals from unsaturated organics using water as a hydrogen source. However, ECH is limited by the low solubility of substrates when operated under aqueous conditions, by electrical losses when performed in organic electrolytes and, in general, by low faradaic efficiency and fastidious work-up. Here, we show that a Pickering emulsion compartmenting organic substrates and aqueous electrolytes in different phases enables efficient ECH at the interface. We designed a construct comprising Pd nanoparticles immobilized on positively charged carbon nanotubes that localizes at the interface to act as both emulsion stabilizer and electrocatalyst. Applied to the ECH of styrene, the system delivers ethylbenzene at high faradaic efficiency (95.0%) and mass specific current density (–148.1 mA $${{{\mathrm{mg}}}}_{{{{\mathrm{Pd}}}}}^{ - 1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mi>mg</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Pd</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> ). The system combines good substrate solubility, high conductivity and simplified product isolation, and has proved applicable to the conversion of various alkenes. This strategy may thus provide alternative solutions to the ECH of substrates with low water solubility, such as bio-oil and bio-crude.