United States Patent Patented July 8, 1958 2 of Supplying a Protective Coating to a Nickel-Kieselguhr Catalyst in the Absence of Atomspheric Oxygen

2,842,504 United States Patent Patented July 8, 1958 2 of Supplying a protective coating to a nickel-kieselguhr catalyst in the absence of atomspheric oxygen. Other objects and advantages of this invention will be 2,842,564 apparent to one skilled in the art upon reading this dis HYDROGENATON CATALYST 5 closure. Rufus W. Jones, Bartiesvie, Okla., assignor to Philips I have discovered that active nickel-kieselguhr hydro Petroleum Company, a corporations e. Delaware genation catalysts can be coated with rubbery polymers and that Stich coated catalysts retain a high state of No Drawing. Application August 23, 1954 activity over a long period of time and that the coating Serial No. 45i,702 can be easily and quickly removed when the catalyst is to be employed in the hydrogenation reaction. 4 Claims. (CE. 252-436) Nickel-kieselguhr catalysts are preferred for the hy drogenation of rubbery poiymers, however, other active catalysts, including Raney nickel, copper chromite, molyb This invention relates to hydrogenation catalysts. in 5 denum sulfide, finely divided platinum, finely divided one of its more specific aspects it relates to a method palladium, platinum oxide, chromium oxide and the like, for the protection of high activity nickel catalyst pre can be used in such hydrogenation reaction. Thus cata pared for use in hydrogenation reactions. Sin another of lysts which are composed of reduced metal or metallic its more specific aspects it relates to a novel hydrogena compounds, which are pyrophoric or otherwise adversely tion catalyst capable of retaining its activity during long affected by oxygen can be protected by a coating of periods of storage. hydrogenated rubbery polymer of butadiene and cata in the hydrogenation of unsaturated compounds and lysts so coated can be stored for extended periods of time particularly in the hydrogenation of rubbery polymers, with substantially no loss of activity. metal catalysts are used. These metal catalysts and par The catalysts used in the hydrogenation reactions con ticularly nickel catalysts are prepared and used in a high templated are well known and methods for their prepa state of activity. ration are also well known. The nickel-kieselguhr cata The hydrogenation of rubbery polymers is usually car lysts preferred for the hydrogenation of rubbery poly ried out by charging a polymer, such as a butadiene poly mers can be prepared by Saturating kieselguhr with a mer, substantially free of salts or other materials which reducible nickel compound such as nickel hydroxide after might act as hydrogenation catalyst poisons, into a suita which at least a portion cf tile nickel compound in the ble hydrogenation reactor in the form of a solution or mixture is reduced to elemental nickel in a stream of dispersion in a suitable medium. hydrogen at elevated temperature. The system can then After the polymer, dissolved in the solvent raedium, be flushed with an inert gas stich as nitrogen or carbon has been introduced into the reactor, the hydrogenation dioxide, if desired, or the hydrogen atmosphere main catalyst is added, hydrogen is added, and the temperature tained and the nickel-kiesselguhr catalyst is then quenched raised to a suitable level so as to initiate the reaction. with a suitable solvent such as methylcycichexane. The reaction can be continuous or batch-wise. When suf A nickel-kieseguhr catalyst having a particle size be ficient hydrogenation has been effected, usually as in tween 1 and 8 microns and which has been activated at dicated by a decrease in unsaturation or a drop in hy a temperature between 500 and 800 F. for a period of drogen pressure, the reaction is stopped and the solution 40 several hours during which period hydrogen is passed treated by suitable means, such as by filtering, centrifug thereover, is preferably employed in the hydrogenation ing, and the like, so as to remove the catalyst. Hydro of rubbery polymers to form thermoplastic material. The genated rubbery poiymer is then separated from the nickel-kieselguhr catalyst activated as hereinbefore de solvent by suitable means such as evaporating the solvent scribed is in a state of high activity because such treat from the polymer. The polymer can be recovered by 5 ment reduces at least a part of the nickel compound to spray drying or by drum drying so as to remove the elemental nickel, generally 35 to 40 percent of the nickel solvent from the polymer. being reduced, the reduced nickel content, however, some Suitable solvents include saturated cyclic hydrocarbons times varying from approximately 10 to 50 percent. such as cyclohexane, methylcyclohexane, decalin, and the The active, elemental nickel is pyrophoric and when ex like, preferably boiling above atmospheric temperature. 50 posed to oxygen undergoes instantaneous exothermic re Aromatic hydrocarbons, such as benzene aid toluene; action to such an extent that it can be a fire hazard. cyclic ethers, such as dioxane; and parafiinic hydrocar Catalytic activity is lost immediately and thus a very bons such as isooctanes, isopentanes, and normal hep definite problem exists in the preparation and handing tane; hydro aromatic hydrocarbons such as tetrain; and of these highly active hydrogenation catalysts. the like, can also be used. Although any of the above According to the practice of this invention, the catalyst solvents or a mixture of any of the above solvents can prepared in the above cutlined procedure can be pre be employed in the hydrogenation of rubbery polymers, served and prepared for storage by treating the catalyst methyicyclohexane is the preferred solvent. in the following manner. The catalyst as prepared above Each of the following objects is attained by at least is coated with a hydrogenated rubbery polymer by 60 quenching the catalyst in the above quenching step with one of the aspects of this invention. a solution of hydrogenated rubbery polymer dissolved it is an object of this invention to provide a method for in the quench Solvent such as methylcyclohexane. It is preserving the activity of hydrogenation catalysts. important that the catalyst be introduced into such solu It is an object of this invention to provide a method tion as quickly as possible after its preparation and in for preserving the activity of nickel-kieselguhr hydrogena 65 the absence of oxygen. The mixture of catalyst and tion catalysts. hydrogenated rubbery polymer should be agitated or Another object is to provide a nickel-kieseiguhr catalyst stirred sufficiently so as to intimately contact the catalyst coated with a hydrogenated rubbery polymer. and the dissolved hydrogenated rubbery polymer so that Another object is to provide an active hydrogenation the particles of catalysts are completely coated with the catalyst capable of being handled and stored without 70 polymer dissolved in the solvent. The mixture is then loss of activity. dried by any suitable means such as drum drying or spray Another object of this invention is to provide a method drying. After drying, the catalysts is found to be coated 2,842,504 4. with a film of hydrogenated rubbery polymer and the hexane was charged to a hydrogenation reactor along with catalyst so coated can be stored until needed without 0.25 part by weight of the above kieselguhr-nickel catalyst substantial loss of catalytic activity. The thickness of per part of polybutadiene and the reactor pressured to the film upon the catalyst can be controlled by regulating 500 p.s. i. g. with hydrogen. The temperature was then the amount of hydrogenated rubbery polymer dissolved siowly raised to 400 F. and maintained at that level for in the solvent which is used to quench the nickel-kiesel 3 hours. The pressure was maintained at 500 p.s. i. g. guhr catalyst. by addition of hydrogen at 15 minute intervals. The polymers which can be used in the invention in The catalyst was removed from the resulting dispersion clude unhydrogenated and hydrogenated polybutadiene, by filtration and discarded and the product recovered by butadiene-styrene, isoprene-styrene copolymers and the evaporation of the methylcyclohexane. The hydrogen like and mixtures of such anhydrogenated arid hydro afed pcyner had an unsaturation value of 0.8 percent. genated polymers and copolymers. The unhydrogenated Several batches of the catalyst as prepared above were polymers should be solid and non-sticky, to the extent that coated with varying amounts of hydrogenated rubbery coated particles of catalyst will not agglomerate to form polymer of butadiene in the following manner: Small a solid mass. The coated particles should remain free 5 amounts of the catalyst (2.35 grams) in methylcyclo flowing under normal storage conditions. Unhydroge:- hexane were placed in each of five test tubes, and an addi ated rubbery polymers, such as polybutadiene, having a tional 10 milliliters of methylcyclohexane was added to Mooney value above about 50 (ML-4) measured at each tube. Small incremental amounts of a dilute Solti 212° F. are generally satisfactory. tion of hydrogenated rubbery polymer of butadiene in Polymers and copolymers having a Mooney value above methylcyclohexane solution were then added to each tube. about 15 can be hydrogenated so as to produce free-flow The tubes were then stoppered and shaken for ten minutes, ing coated catalyst by hydrogenating to 50 percent lin after which the contents were removed and spray dried. saturation or less. The unsaturation is based upon the The data for these runs are tabulated below. theoretical value of 100 percent for the unhydrogenated polymer. 25 M. Hydro- Wt. of Hy- Wt. Percent, genated drogenated Hydrogen Unsaturation is conveniently determined by the iodine Wt. of Catalyst, M. of Rubbery Rubbery lated Rubbery chloride addition method described by Lee, Kolthoff and Grains MCE Polymer Polymer Polymer Added Solution Added Present in Mairs in curnal of Polymer Science, volume 3 (1948), Added (grans) Coated Cata at pages 66 to 84.

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