Grant C Bailey

Catalytic polymerization of olefins

1. Nickelous oxide — synthetic aluminum silicate (tablet form) catalysts prepared by precipitation or impregnation show considerable activity for the polymerization of ethylene at 300° and atmospheric pressure. Aluminum silicate is not itself a catalyst in this reaction. 2. When nickel is replaced by iron, cobalt, or copper in a nickelous oxide — aluminum silicate catalyst, the products are inactive for the polymerization of ethylene. 3. Aluminum silicate that has been treated with a solution of alkali is unsuitable as a carrier for nickelous oxide; this is in good agreement with the view of the activity of hydrogen ions in an aluminum silicate.

Formation of high polymers on solid surfaces I. Theoretical study of mechanisms

Abstract Four models are set up for polymerization on solid surfaces. In two of the models, it is assumed that all adsorption sites have the same adsorption energy. The first of these (Rideal mechanism) assumes that polymerization occurs by reaction of monomer in the gas phase with adsorbed monomer or adsorbed, growing polymer chains. The second model (Langmuir-Hinshelwood mechanism) assumes that polymerization occurs by reaction of an adsorbed monomer molecule with an adjacently adsorbed monomer molecule or growing polymer chain. The other two models are the counterparts of the first two with a variation of adsorption energies among the sites. With all adsorption sites of equal energy, it is shown that in both mechanisms there is a unique weight average molecular weight for each number average molecular weight. Weight average-number average molecular weight ratio, ( W N ), a measure of the broadness of molecular weight distribution, is shown to be in the range, 1 ⩽ W N ⩽ 2, for all values of velocity constants and pressure. In the Rideal mechanism, number and weight average molecular weights and rates of reaction increase without limit as pressure is increased. In the Langmuir-Hinshelwood mechanism, molecular weights and rates approach a maximum value asympotically as pressure is increased. With a distribution of adsorption energies, weight average-number average molecular weight ratios ( W N ) can have values far in excess of 2 for both mechanisms. Molecular weights and rates of reaction again level out with increasing pressure for the Langmuir-Hinshelwood mechanism, and increase without restriction in the Rideal mechanism.

Formation of high polymers on solid surfaces II. Polymerization of ethylene on chromium oxide-silica-alumina catalysts

Abstract The four models of the preceding paper (1) (Part I) are compared with the experimental results of polymerizing ethylene over chromium oxide-silica-alumina catalyst. Experimental curves are shown for number average molecular weights, weight average molecular weights, their ratios, and rates of polymerization as functions of pressure. The effects of temperature variations on these quantities are discussed qualitatively. The conclusion is reached that the Langmuir-Hinshelwood mechanism on an energetically heterogeneous surface duplicates the general character of the experimental curves most closely.