The chemistry and catalysis of the water gas shift reaction: 1. The kinetics over supported metal catalysts

The water gas shift (WGS) reaction (CO + H2O → CO2 + H2) is catalyzed by many metals and metal oxides as well as recently reported homogeneous catalysts. In this present paper the kinetics of the WGS reaction as catalyzed by alumina-supported Group VIIB, VIII, and IB metals are examined. For several metals a strong effect of support on metal activity is observed. For example, the turnover number (rate per surface metal atom) of Pt supported on Al2O3 is an order of magnitude higher than the turnover number of Pt on SiO2. The turnover numbers (at 300 °C) of the various alumina-supported metals studied for WGS decrease in the order Cu, Re, Co, Ru, Ni, Pt, Os, Au, Fe, Pd, Rh, and Ir. For these metals the range of activity varies by more than three orders of magnitude. It is shown that a volcano-shaped correlation exists between the activities of these metals and their respective CO heats of adsorption. The partial pressure dependencies of the reactants on these metals are reported for the first time. Over most metals the CO order of reaction is near zero and the H2O order of reaction is near 12. A reaction sequence including formic acid as an intermediate is proposed in order to account for the apparent bifunctionality of the supported catalyst systems. This approach leads to a power rate law, r = kPCOXPH2OZ(1 − X)2, an expression shown to be consistent with the experimental parameters obtained in these kinetic studies.

[1]  G. Bond.  Catalysis By Metals , 1962 .

[2]  T. Onishi,et al.  Dynamic treatment of chemisorbed species by means of infra-red technique. Mechanism of decomposition of formic acid over alumina and silica , 1967 .

[3]  Michel Boudart,et al.  Kinetics of chemical processes , 1968 .

[4]  C. L. Thomas,et al.  Catalytic processes and proven catalysts , 1970 .

[5]  Makihiko Masuda,et al.  ISOTOPIC STUDY OF WATER GAS REACTION CATALYZED BY PLATINUM , 1974 .

[6]  M. Shelef,et al.  Ammonia Formation in the Catalytic Reduction of Nitric Oxide. III. The Role of Water Gas Shift, Reduction by Hydrocarbons, and Steam Reforming , 1974 .

[7]  R. L. Klimisch,et al.  The dual state behavior of supported noble metal catalysts , 1974 .

[8]  M. Vannice.  The catalytic synthesis of hydrocarbons from H2CO mixtures over the group VIII metals: I. The specific activities and product distributions of supported metals , 1975 .

[9]  R. Laine,et al.  Homogeneous catalysis by ruthenium carbonyl in alkaline solution: the water gas shift reaction , 1977 .

[10]  M. Vannice,et al.  The catalytic synthesis of hydrocarbons from H2CO mixtures over the Group VIII metals: V. The catalytic behavior of silica-supported metals , 1977 .

[11]  D. Grenoble.  The chemistry and catalysis of the water/toluene reaction: 1. The specific activities and selectivities of the Group VIII metals supported on Al2O3 , 1978 .

[12]  S. C. Fung,et al.  Strong metal-support interactions. Group 8 noble metals supported on titanium dioxide , 1978 .

[13]  Y. Amenomiya.  Active sites of solid acidic catalysts: II. Water-gas conversion on alumina and some other catalysts☆ , 1978 .

[14]  D. Grenoble.  The chemistry and catalysis of the water/toluene reaction: 2. The role of support and kinetic analysis , 1978 .

[15]  Y. Amenomiya.  Active sites of solid acidic catalysts: III. Infrared study of the water gas conversion reaction on alumina , 1979 .

[16]  D. Grenoble.  The chemistry and catalysis of the toluene hydrodealkylation reaction: I. The specific activities and selectivities of Group VIIB and Group VIII metals supported on alumina , 1979 .

[17]  B. Gates,et al.  Chemistry of catalytic processes , 1979 .