BY Ty 1. AGENT 3,412,040 United States Patent Office Patented Nov

Nov. 19, 1968 P. SACCARDO EA 3,412,040 CHROMYL-OXYHALIDE TREATED CARRIER AS AN OLEFIN FOLYMERIZATION CATALYST Filed Aug. 5, 1964 FLUIDZED-BED E-Wasta Gasos REACTOR - SiOlAO : O. 15O-8OOC (Activation) PIETRO SACCARDO GIANNI TRADA VIITORIO FATTORE JEAN HERZENBERG INVENTORS. BY ty 1. AGENT 3,412,040 United States Patent Office Patented Nov. 19, 1968 1 2 3,412,040 the oxide which appears to be present as a molecular CHROMYL-OXYHALIDE TREATED CARRIER AS layer. AN OLEFIN POLYMERIZATION CATALYST It is the principal object of the present invention to Pietro Saccardo, Gianni Trada, Vittorio Fattore, and Jean provide an improved method of producing chromium Herzenberg, Milan, Italy, assignors to Montecatini Edi 5 containing catalytic systems suitable for use in the polym son, S.p.A., Milan, Italy, a corporation of Italy erization of olefins and for similar purposes. Filed Aug. 5, 1964, Ser. No. 387,732 Still another object of this invention is to provide a Claims priority, application Italy, Aug. 9, 1963, catalyst system having particular effectiveness in promot 16,875/63 2 Claims. (Cl. 252-441) ing polymerization reactions as described above. 10 These objects and others which will become apparent hereinafter are attained, in accordance with the method of the present invention, by treating a catalyst carrier ABSTRACT OF THE DISCLOSURE with a chromium oxychloride and, more specifically, with A single-component catalyst for the polymerization of a chromyl halide containing chlorine. The catalyst car alpha-olefins, consisting essentially of a silica-containing rier, thus coated with the chromium compound, is then catalyst carrier reacted with chromyl chloride (CrO2Cl2) subjected to activation by heating in the presence of a and/or chromyl fluorochloride (CrOFCI), alone or in fluid such as pure orygen, oxygen-containing gases or the presence of chromyl fluoride (CrOF), and there inert gases. It has been found that catalyst systems pro after activated for subsequent direct use in the polymer duced in this manner, i.e. by impregnating the catalyst ization process by heating the single-component catalyst 20 carrier with a chromyl chloride and activating the result ing mass, are particularly active and effective in the po in oxygen or inert gas to a temperature of 300 to 600 C. lymerization of alpha-olefins to the corresponding poly olefins. The catalyst carrier can, according to the present invention, be any of those considered heretofore to be Our present invention relates to improved catalytic Suitable carriers for chromium compounds. Suitable car systems and a method of producing such Systems. riers, for the purposes of the present invention, are silica, More particularly, this invention is concerned with cata alumina, kieselguhr, pumice, aluminum phosphate and lyst systems containing chromium (e.g. as chromium titanium dioxide as well as mixtures thereof. When the oxides) deposited upon a catalyst carrier or Support. polymerization of alpha-olefins is desired, silica, alumina Chromium-containing catalyst systems are commonly 30 or silica-aluminas are most suitable. used in the polymerization of various monomers and, According to another feature of this invention, the especially, olefinic monomers. Thus, catalyst compositions treatment with chromyl chloride is effected in the liquid of this general type can be used in the polymerization phase whereby the liquid chromyl chloride contacts the of alpha-olefins (e.g. ethylene) in the production of cor catalyst carrier directly. In a modification of the liquid responding polyolefins. - 3. 5 phase technique, the chromyl chloride can be dissolved in In most cases, the catalyst system comprises a carrier a solvent (e.g. 1,2-dibromoethane nitrobenzene, chloro consisting predominantly of a silicon oxide (e.g. silica) form and carbon tetrachloride). In another advantageous and/or alumina. The chromium oxide most suitable for method of treating the catalyst carrier with chromyl. producing polyolefins and for depositing on carrier of this chloride, the latter is constituted as part of a gas stream type is chromium trioxide. In earlier techniques for the 40 which is employed to contact the carrier. In this case, it production of catalyst systems, the carrier was usually is desirable to convey the chromyl chloride to the carrier impregnated with a solution of chromium trioxide or a in a gas stream containing an inert gas (e.g. nitrogen), chromium salt which, upon heating, yields chromium tri i.e. a gas incapable of reacting with the chromyl com oxide, chromium sesquioxide or mixtures thereof. The pound. According to another feature of this invention, the catalyst system obtained in this manner can then be ac chromyl chloride (CrO2Cl2) is reacted with hydrogen tivated by heating to relatively high temperatures in the flouride to produce chromyl fluoride, which reacts with a presence of oxygen or oxygen-containing gases (e.g. air). silicecus-catalyst carrier as described in our copending In our copending application Serial No. 379,608, filed application referred to above. The reaction also yields July 1, 1964, and entitled: "Process for producing cata chromyl fluorochloride which is capable of reacting with lyst compositions and the product of this process,” how 50 silica to yield silicon tetrafluoride and deposits a chromyl ever, we describe and claim an improved method of pro containing compound upon the surface of a carrier. ducing catalyst systems of the general class referred to It has been discovered that the technique of the present above. In this improved technique, a chromium oxide invention is surprisingly effective in depositing relatively can be deposited upon a siliceous carrier by reacting the large quantities of chromium on thet carrier. Catalyst carrier with a fluorine-containing compound of chromium, systems of this type, however, are most effective when preferably a chromium oxyfluoride, to yield volatile sili the chromium content is between substantially 0.1 and con fluoride and chromium oxides which are thus de 10% by weight of the catalyst system and preferably be posited on the surface of the silicon contaihing carrier. tween 0.1 and 4% by weight when the catalyst is em While this system has application to other chromium com ployed in the polymerization of alpha-olefins. Activation pounds containing fluorine, it is desirable to make use 60 of the catalyst system is effected, according to this inven of chromyl fluoride (CrOF2) thereby ensuring that the tion, by heating it to temperatures ranging between sub deposited compound is an oxide. The preparation of the stantially 150 and 800° C. in the presence of oxygen, catalyst system in this manner, by displacement of atoms an oxygen-containing gas or an inert gas (e.g. nitrogen). of silicon from the carrier, renews the effective surface of Activation temperatures between 300 and 600 C. are the catalyst so that the chromium oxide is deposited at most desirable when the catalyst system is to be em the newly formed faces which give rise to particularly ployed for the production of alpha-olefins. It should be effective active centers. There is evidence that the method further noted that catalyst systems prepared in accord results in the formation of a uniform layer of Substan ance with the principles of our invention, using chromyl tially constant thickness on the carrier, presumably be chlorides and chromyl fluorides, in conjunction with or cause the initial molecular layer acts as a barrier to fur 70 without activation have been found to evidence synergis ther reaction of the fluorinated compound with silicon. tic activity giving rise to catalyst efficiencies in excess of Thus the reaction terminates locally after formation of those obtained when the chromyl fluoride and the chromyl 3,412,040 3 4. chloride are used alone. Still higher efficiencies result through the second reactor. After this treatment a cata when activation is employed. lytic mass, active in the polymerization of ethylene, was The invention will become more readily apparent from obtained and found to contain 1.58% by weight chro the following description, reference being made to the mium. accompanying drawing, the sole figure of which is a 5 Example V diagrammatic view of an apparatus for producing a cata 1.4 grams of chromyl chloride and 23 grams of y-au lyst system according to this invention, and the specific mina (Ketjen grade A), previously dried for 3 hours at examples given hereunder as the best mode known to 500 C., were introduced into an apparatus analogous to the inventors for taking advantage of the present dis the one described in Example IV. The chromyl chloride covery. O was deposited on the alumina as set forth in this Example. Example I After heating at 300° C. for about half an hour, in stream 0.9 grams of chromyl chloride (CrO2Cl2) were intro of dry air, an activated catalytic mass was obtained con duced into a reactor provided with a bubbling pipe and taining 2.14% by weight of chromium. an outlet pipe at the top of the reactor. The bubbling Example VI pipe was connected with a nitrogen source, whereas the In’o a 0.5 liter glass flask equipped with stirrer and re outlet pipe was connected with a second reactor, which flux condenser were introduced 120 ml. of carbon tetra was constructed so as to oeprate according to the fluidized chloride and 4.5 grams of chromyl chloride. With stirring bed technique; the latter reactor contained 10 grams of 50 grams of silica-alumina (Davison, 87% by weight sil silica-alumina (87% by weight silica and 13% by weight ica and 13% by weight alumina) previously dried for 3 alumina). By bubbling nitrogen through the chromyl hours at 400° C. were introduced. chloride in the first vessel, vapors of this component Were After stirring of the suspension thus produced for 90 conveyed to the silica-alumina of the second vessel which minutes at about 70° C.

Load more