Chemistry of acetylene on platinum (111) and (100) surfaces.
An ultra-high vacuum experimental study of acetylene chemisorption on Pt(111) and Pt(100) and of the reaction of hydrogen with the acetylene adsorbate has established distinguishing features of carbon-hydrogen bond breaking and making processes as a function of pressure, temperature, and surface crystallography. The rates for both processes are substantially higher on the Pt(100) surface. Net acetylene-hydrogen processes, in the temperature range of 20 degrees C to approximately 130 degrees C, are distinctly different on the two surfaces: on Pt(100) the net reaction is hydrogen exchange ((1)H-(2)H exchange) and on Pt(111) the only detectable reaction is hydrogenation. Stereochemical differences in the acetylene adsorbate structure are considered to be a contributing factor to the differences in acetylene chemistry on these two surfaces.
Materials and Molecular Research Division, Lawrence Berkeley Laboratory, Berkeley, California 94720.
E L
EL
Muetterties
M C
MC
Tasi
S R
SR
Kelemen