PARTIAL OXIDATION OF CYCLOHEXANE WITH REDUCTIVELY ACTIVATED DIOXYGEN ON SMCL3 SUPPORTED ON GRAPHITE DURING H-2-O2 FUEL-CELL REACTIONS

The oxidation of cyclohexane to cyclohexanol (CyOH) and cyclohexanone (CyO) on SmCl3 supported on graphite (SmCl3/Gr) utilizing an H-2-O2 fu el cell system has been studied by means of kinetic and electrochemica l techniques. O2 is reductively activated on SMCl3/Gr with e- and H+ w hich are supplied from the anode. The kinetic and electrochemical resu lts have suggested that the current is determined by the electrochemic al reduction of O2, but the oxygenate formation depends strongly on th e stationary concentration of active oxygen (O) generated on SmCl3/Gr . The optimum rate of formation of the products was obtained at a cath ode potential of -0.24 V (vs. Ag\AgCl). The active site on SmCl3/Gr wa s suggested to be a Sm3+ coordinated with surface functional groups on the graphite. The reaction between the O and cyclohexane proceeds th rough a non-electrochemical reaction and produces CyOH and CyO in para llel. The selectivity of the products on SmCl3/Gr did not change appre ciably under different cathode potentials and O2 pressures. However, t he selectivity varied widely for the oxidation on FeCl3/Gr. These obse rvations suggest different O species between SmCl3/Gr and FeCl3/Gr.