Oligomerization of Propylene with Silica-Alumina and Nickel Oxide-Silica-Alumina Catalysts

Oligomerization of propylene with silica-alumina and nickel oxide-silica-alumina (Ni content: 13wt%) catalysts was studied under the high pressure (25-50kg/cm2) continuous flow system. The reaction temperature was varied in the range of 80-350°C and the space velocity 5, 000-10, 000ml-N. T. P. feed/ml-catalyst/hr. From the experimental results obtained, the following conclusions may be drawn.1) In the presence of the nickel oxide-silica-alumina catalyst, propylene could be polymerized under mild reaction temperature (around 80°C). In this case, dimerization of propylene predominated and the hexene thus produced contained only negligible amount of 3-methyl pentenes.2) While, in the presence of the silica-alumina catalyst, higher temperatures than 200°C were required for propylene polymerization. In this case, dimerization of propylene was a minor reaction among the polymerization reactions, and the dimerization product hexene contained considerable quantities of 3-methyl pentenes.3) As to the formation of 3-methyl pentene from propylene, Uchida et al. proposed a mechanism, in which 3-methyl pentene was formed by the decomposition of the cyclobutane ring produced by the combination of two propylene molecules adsorbed on the active center of nickel oxide-silica-alumina catalyst. However, judging from our experimental results, the formation of 3-methyl pentenes was not a special feature of nickel oxide-silica-alumina catalyst. High temperature seemed to favor the formation of 3-methyl pentenes, since a considerable quantity of 3-methyl pentene was obtained under high reaction temperatures, even in the presence of the silica-alumina catalyst.