2732. PYZEL, E. D. (Shell Development Co.). Hydrogenation of Olefinic Polymers. United States Patent 2,147,268, Feb. 14, 1939. Chem. Abs., vol. 33, 1939, p. 3810.

Multistage continuous process for effecting the catalytic hydrogenation of an olefin-polymer material to the corresponding saturated material by reaction with free H₂ in the presence of an active hydrogenation catalyst when the polymer material contains more than a critical concentration of a catalyst-poisoning impurity capable of poisoning the hydrogenation catalyst used, which comprises passing the polymer material together with less than a stoichiometrical amount of free H₂ into contact with the hydrogenation catalyst in the 1^st stage under such conditions that only a part of the polymer material is hydrogenated, separating normally gaseous constituents from the treated material leaving the first hydrogenation stage, and then passing the partly hydrogenated material, which has been substantially freed of catalyst-poisoning impurities by treatment in the 1^st hydrogenation stage, together with more than a stoichiometrical amount of free H₂ into contact under hydrogenation conditions with the hydrogenation catalyst in a subsequent hydrogenation stage, whereby substantially complete hydrogenation of the polymer material is effected with substantially no decrease in activity of the catalyst in any hydrogenation stage subsequent to the first. Describes arrangement of apparatus.