ISSN:
1572-879X
Keywords:
Surface carbide
;
surface nitride
;
intermediates
;
NO + H2 reaction
;
methanation reaction
;
catalysis on single crystal
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract A key intermediate of the methanation reaction on nickel catalyst is a carbidic carbon. Accumulated carbidic intermediates on Ni(100) gives a p(2×2) p4g structure, whereas that on Ni(111) is too complex to be solved. A single domain carbide layer accidentally on Ni(111) allowed us to solve the structure explicitly. Comparison of the carbide layer on Ni(100) and that on Ni(111) showed that the carbon atoms are arranged by forming the same ordered structure. The carbide layers prepared on Ni(100), Ni(111) and Ni(110) have almost equal decomposition temperatures. Consequently, we can conclude that the same overlayer compound is formed on the three surfaces. Furthermore, the hydrogenation of the p4g carbide on Ni(100) occurs at almost equal rate to the turnover frequency of the catalytic methanation reaction. The structure insensitive methanation reaction on Ni(100), Ni(111) and Ni(110) is responsible for the same intermediate compound on these surfaces. The same strategy was applied to the reaction of NO with H2 on Pd(100), Rh(100) and Pt-Rh(100) surfaces, and ac(2×2)-N overlayer was isolated on each of these. The hydrogenation of the isolatedc(2×2)-N produced predominantly NH species, which indicates slow NH species hydrogenation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00767183
