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>Multi-functionality of rhodium-loaded MOR zeolite: production of H2 via the water gas shift reaction and its use in the formation of NH3
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Multi-functionality of rhodium-loaded MOR zeolite: production of H2 via the water gas shift reaction and its use in the formation of NH3
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机译：Multi-functionality of rhodium-loaded MOR zeolite: production of H2 via the water gas shift reaction and its use in the formation of NH3
Rh-loaded mordenite (RhMOR) zeolite was investigated as a catalyst that can use CO + H2O as a H2 source for NO reduction. Operando IR measurements showed that CO was captured in the form of Rh dicarbonyl species ([Rh(CO)2]~+) in zeolite, which reacts with H2O to form H2 in situ via the water gas shift (WGS) reaction (CO + H2O → CO2 + H2) at >350 °C. Temperature-programmed surface reaction (TPSR) measurements under a flow of NO + CO + H2O monitored both the surface ad-species and outlet gas components. At >250 °C, the decrease in the outlet NO and CO as well as the increase in the IR intensity corresponding to NH4~+ in zeolite were observed, indicating that the formed H2 was directly used for the reduction of NO into NH3, which was stored at the Bronsted acid sites (BAS). The mechanism of the WGS reaction was theoretically investigated; the predicted rate-determining step was the dissociation of H2O on [Rh(CO)2]~+ to give [Rh(CO)(COOH)(H)]~+ and its activation barrier was 176 kJ mol~(-1). The present study demonstrates the effective use of the multi-functionality of the isolated active metal anchored in zeolite as well as the potential utilization of CO + H2O as a H2 source.
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