caa a22 4500 606174095 CHVBK 20210128100736.0 cr unu---uuuuu 210128e20150401xx s 000 0 eng 10.1007/s11244-015-0368-y doi (NATIONALLICENCE)springer-10.1007/s11244-015-0368-y Intermediates Arising from the Water-Gas Shift Reaction over Cu Surfaces: From UHV to Near Atmospheric Pressures [Elektronische Daten] [K. Mudiyanselage, S. Senanayake, P. Ramirez, S. Kundu, A. Baber, F. Yang, S. Agnoli, S. Axnanda, Z. Liu, J. Hrbek, J. Evans, J. Rodriguez, D. Stacchiola] The water-gas shift (WGS) reaction $$ ({\text{CO}} + {\text{H}}_{ 2} {\text{O}} \to {\text{CO}}_{ 2} + {\text{H}}_{ 2} ) $$ ( CO + H 2 O → CO 2 + H 2 ) is a key process to the production of high purity H2 from gas streams rich in CO. The identification of the WGS reaction mechanism and the probable stable intermediates is critical to design the catalyst structure, optimize composition and tune reaction kinetics/thermodynamics to achieve the optimum selectivity and activity. In this study, first the WGS reaction steps on Cu(111) have been studied using X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy under ultra-high vacuum (UHV) conditions. Then the interactions of H2O with CO on Cu(111) have been studied under elevated pressures (90 mTorr CO+30 mTorr H2O) at 300-575K with ambient pressure XPS. Under UHV conditions, non-dissociative adsorption of H2O on Cu(111) and Cu2O/Cu(111) was observed. Whereas H2O readily dissociates, by breaking the O-H bond on a chemisorbed O layer on Cu(111) to form OH species. Even though this OH interacts with adsorbed CO, it does not react to form any associative intermediate and simply desorbs as H2O at 275K under UHV conditions. At ambient pressures, no associative intermediates species, only CO and OH, were observed in the reaction of CO with H2O although the catalytic production of H2 can be detected under these conditions. Since intermediate species other than CO and OH were not observed on Cu(111) under reaction conditions, we concluded that the redox mechanism is the dominant WGS pathway on Cu(111). The coupling of Cu to an oxide, Cu-CeO2 catalyst, or a carbide, Cu-TiC catalyst, favors an associative mechanism and produces a very large increase in the rate for the production of H2 through the WGS. Springer Science+Business Media New York, 2015 Water-gas shift nationallicence Hydrogen production nationallicence Copper nationallicence Ceria nationallicence Titanium carbide nationallicence Mudiyanselage K. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Senanayake S. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Ramirez P. Facultad de Ciencias, Universidad Central de Venezuela, 1020A, Caracas, Venezuela aut Kundu S. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Baber A. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Yang F. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Agnoli S. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Axnanda S. The Advanced Light Source, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA aut Liu Z. The Advanced Light Source, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA aut Hrbek J. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Evans J. Facultad de Ciencias, Universidad Central de Venezuela, 1020A, Caracas, Venezuela aut Rodriguez J. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Stacchiola D. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut Topics in Catalysis Springer US; http://www.springer-ny.com 58/4-6(2015-04-01), 271-280 1022-5528 58:4-6<271 2015 58 11244 https://doi.org/10.1007/s11244-015-0368-y text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11244-015-0368-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Mudiyanselage K. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Senanayake S. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Ramirez P. Facultad de Ciencias, Universidad Central de Venezuela, 1020A, Caracas, Venezuela aut NATIONALLICENCE 700 1- Kundu S. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Baber A. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Yang F. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Agnoli S. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Axnanda S. The Advanced Light Source, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Liu Z. The Advanced Light Source, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Hrbek J. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Evans J. Facultad de Ciencias, Universidad Central de Venezuela, 1020A, Caracas, Venezuela aut NATIONALLICENCE 700 1- Rodriguez J. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 700 1- Stacchiola D. Chemistry Department, Brookhaven National Laboratory, 11973, Upton, NY, USA aut NATIONALLICENCE 773 0- Topics in Catalysis Springer US; http://www.springer-ny.com 58/4-6(2015-04-01), 271-280 1022-5528 58:4-6<271 2015 58 11244