The reaction of ethylene catalyzed by clean molybdenum foil is examine
d between 800 and 880 K. Products up to C-7 are detected in measurable
quantities and hydrocarbons up to C-8 are observed. The product distr
ibution is well described by a Schulz-Flory function where a plot of I
n(W-n/n) versus n, where W-n is the yield of each C-n hydrocarbon, is
a good straight line. Analysis of the slope and intercept of the distr
ibution shows that the slope has a zero-order ethylene pressure depend
ence and varies with temperature with an activation energy of 4.6 +/-
0.6 kcal/mol, while the intercept has a pressure dependence of 1.3 +/-
0.3 and an activation energy of 46 +/- 4 kcal/mol. A kinetic model is
proposed that successfully accounts for these pressure dependences. T
hese data suggest that the activation energy for degenerate ethylene m
etathesis should be 55 +/- 5 kcal/mol and that the reaction should be
first order in ethylene. These kinetic parameters are in good agreemen
t with those found experimentally for the non-degenerate metathesis of
propylene.