Olefin Polymerization with Acid Catalysts

Polymerization of Light Olefins over Nickel Oxide–Silica-Alumina

“…The products obtained from propylene polymerization were, in general, those which would be expected according to the car- bonium ion mechanism of polymerization as proposed by Whitmore {14)• The fact that more than a third of the hexenes fraction consisted of straight-chain hexenes indicates, however, that the ratio of primary to secondary carbonium ions formed from propylene at this temperature may be higher than has been supposed (8). The difference in proton affinities for carbon atoms 1 and 2 is not as great in propylene as in isobutene (5).…”

“…Ethylene has been polymerized at 250°to 350°C. in the presence of phosphoric acid (7) to give products which indicate conjunct polymerization of a type different from that obtained in thermal polymerization (8,7,18). Cobalt-charcoal catalysts have been used for the dimerization of ethylene (8).…”

“…in the presence of phosphoric acid (7) to give products which indicate conjunct polymerization of a type different from that obtained in thermal polymerization (8,7,18). Cobalt-charcoal catalysts have been used for the dimerization of ethylene (8). Bailey and Reid (1) discovered that silica-alumina promoted with nickel oxide possessed high activity for the polymerization of ethylene, even at room temperature, and was more active for propylene polymerization than silica-alumina alone.…”

Chemistry of initiation in carbocationic polymerization

“…For example, with a-methylstyrene the concentration of H2SO4 largely determines oligomerization and the composition of product mix (Hersberger and Heiligmann, 1947). Similarly, the oligomerization of propylene gives quite different results with dilute or concentrated (92-109%) H3P04 (Monroe and Galliland, 1938;Langlois, 1953;Bethea, 1956). The minimum temperature for propylene oligomerization is 100-130°C lower with concentrated H3P04 than that with dilute acid (Bethea and Karchmer, 1956).…”

Effect of residence time spectrum in the oligomerisation of isobutene from mixed butenes

“…In such cases, the expression T = V / F (1) does not describe the passage of the reactants accurately; T, V and F being the average residence time, volume of the reaction space, and volumetric throughput respectively. The average time spent by the reactants in the mixing system may be quantified as the sum of all the proportions of the reactants having different retention times multiplied by the corresponding time of stay for each p~r t i o n .~.~ This may be expressed as where n is the number of recirculations of the incoming portions of material in the system before discharge; p is the proportion of feed leaving the mixing system after one circulation F/ W ; q is the proportion of the feed remaining in the mixing system after one circulation, (1 -p ) ; t is the time for one circulation in the mixing system, V / W ; and W is the volumetric circulation rate in the vessel.…”