Effect of\nIsopropanol on the Electrocatalytic Hydrodeoxygenation\nof Guaiacol to Cyclohexane in a Stirred Slurry Reactor: Factorial\nExperimental Design

The production of cyclohexane through the hydrodeoxygenation\nof\nguaiacol is a kinetically challenging process in an aqueous electrocatalytic\nsystem. Adding isopropyl alcohol (IPA) as a polar protic solvent to\nthe aqueous electrolyte in a stirred slurry reactor with a Pt/C catalyst,\nwe demonstrated the production of cyclohexane by electrocatalytic\nhydrodeoxygenation of guaiacol along with intermediate products such\nas phenols and cyclohexanones. Univariate analysis was augmented with\nstatistical experimental design and response surface methodology-based\noptimization to reveal the main and interaction effects of reaction\nvariables such as IPA and methanesulfonic acid content in the catholyte\nunder galvanostatic conditions. The addition of 25% vol. IPA in the\ncatholyte composed of 1.0 M methanesulfonic acid, 0.25 M NaCl, and\n0.1 M guaiacol was most effective for electrocatalytic guaiacol hydrodeoxygenation\nat −66 mA cm<sup>–2</sup> superficial current density\nand 60 °C using 5 g/L 5% wt Pt/C catalyst in the stirred slurry\nreactor. Under these conditions, the energy requirement was low (5.9\nWh mol<sup>–1</sup>), and a high faradaic efficiency (69%)\nwas obtained with a guaiacol conversion of 69.3% and a cyclohexane\nyield of 6.7%. Reaction network analysis revealed an additional pathway\nfor guaiacol conversion in the presence of IPA involving anisole as\nthe intermediate species. Reaction kinetic and mechanistic insights\nare also presented.