fig2

Figure 2. Leaching of gold from used Au/MO_x catalysts. (A) Au source: used Au/ZnO, effect of content of KI equivalent, I^- mol/Au mol; (B) Au source: used Au/ZnO, the effect of cations in iodide, 10 equiv; (C) Au source: used Au/ZnO, the effect of amines, KI, 10 equiv; (D) Au source: used Au/ZnO, effect of alcohol solvents, KI, 10 equiv.; (E) Effect of various used Au/MO_x catalysts, KI, 10 equiv; (F) The photo of used Au/MO_x catalysts before and after leaching process. Oxidative carbonylation reaction condition: amine (1 mmol), CuI (0.02 mmol) solvent 5 mL, CO 1.6 MPa, air 0.4 MPa, T = 60 ^oC, t = 10 h. Au/MO_x: Au/metal oxide.