Multi-functionality of rhodium-loaded MOR zeolite: production of H2via 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 H-2 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 H(2)in situ via the water gas shift (WGS) reaction (CO + H2O -> CO2 + H-2) at >350 degrees 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 degrees 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 H-2 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 H-2 source.

Automated summary

Rh-loaded mordenite zeolite was used as a catalyst for NO reduction using CO + H2O as a H2 source. Operando IR measurements revealed that Rh dicarbonyl species ([Rh(CO)(2)](+)) captured CO in the zeolite, which reacted with H2O to produce H(2)via the water gas shift (WGS) reaction. TPSR measurements showed that the formed H-2 was directly used for NO reduction into NH3. The study also investigated the mechanism of the WGS reaction.