Electrocatalytic Hydrogenation of Guaiacol in Diverse Electrolytes Using a Stirred Slurry Reactor

Abstract

Electrocatalytic hydrogenation (ECH) of guaiacol was performed in a stirred slurry electrochemical reactor (SSER) using 5wt% Pt/C catalyst in the cathode compartment. Different pairs of acid (H2SO4), neutral (NaCl), and alkaline (NaOH) catholyte-anolyte combinations separated by a Nafion((R)) 117 cation exchange membrane, were investigated by galvanostatic and potentiostatic electrolysis to probe the electrolyte and proton concentration effect on guaiacol conversion, product distribution, and Faradaic efficiency. The acid-acid and neutral-acid pairs were found to be the most effective. In the case of the neutral-acid pair, proton diffusion and migration through the membrane from the anolyte to the catholyte supplies the protons required for ECH. Typically, the two major hydrogenation products were cyclohexanol and 2-methoxycyclohexanol. However, ECH at constant cathode superficial current density (-182mAcm(-2)) and higher temperature (i.e., 60 degrees C) favored a pathway leading mainly to cyclohexanone. The guaiacol conversion routes were affected by temperature- and cathode potential-dependent surface coverage of adsorbed hydrogen radicals generated through electroreduction of protons.