Zeolite MCM-22 Modified with Au and Cu for Catalytic Total Oxidation of Methanol and Carbon Monoxide

The goal of this work was to use MCM-22 zeolites for \npreparation of monometallic (Cu or Au) and bimetallic (Cu and Au) \ncatalysts for oxidation reactions. The focus was on precise determination \nof the nature of gold and copper species and their activity in the \noxidation processes. For that purpose several characterization techniques \nwere applied (XRD, $N_{2}$ \nadsorption/desorption, TEM, SEM, UV \n− \nvis, $H_{2}$-TPR, $^{27}\\textrm{Al}$ MAS NMR, FT-IR with the adsorption of pyridine, NO, \nand CO, ESR spectroscopy). They allowed us to de \nfi \nne the following \nspecies formed on MCM-22 surface: metallic gold particles (XRD, UV \n− \nvis), isolated $Cu^{2+}$ \nwith octahedral coordination (UV \n− \nvis, ESR), square planar $Cu^{2+}$ \ncations (ESR, IR), $Cu^{+}$ \nspecies (ESR+NO, FTIR+CO, and FTIR+NO), and oligonuclear clusters \n(UV \n− \nvis) as well as CuO-like species ($H_{2}$ \n-TPR). The presence of gold on the MCM-22 surface modified further by copper \nspecies caused the interaction between two modifiers leading to much easier reduction of CuO-like species and higher mobility of \noxygen-promoting oxidative properties. The bimetallic catalyst was highly active in total oxidation of methanol and CO in the \ntemperature range 523 \n− \n623 K. Cu/Au-MCM-22 zeolite appeared useful for simultaneous removal of CO and methanol (by total \noxidation) from gases emitted from automotive devices and during a variety of industrial process operations.