The catalytic activity and selectivity of a number of aluminosilicate
catalysts with different degrees of crystallinity Z in the conversion
of ethylene to higher hydrocarbons have been studied in a flow-type un
it at atmospheric pressure in the temperature range 300-600 degrees C.
The observed extremal dependence of the overall C2H4 conversion on Z
is explained by the influence of macrokinetic factors on the reaction
with Z > 55%. It is suggested that the initial stage in C2H4 conversio
n is the formation of a surface high-molecular weight ethylene oligome
r. The observed range of products is the result of cracking of the ads
orbed oligomer. (C) 1996 Elsevier Science Ltd.