BE532095A - - Google Patents

Description

       

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   The present invention relates to a novel polymerization process and to novel polymerization products resulting from this process. More particularly, the invention relates to a new process for the polymerization of ethylene, propylene, or mixtures of these two compounds, in the presence of an alkali metal and of a solid catalytic compound containing an oxide of dq. 'a metal from group 6a (left subgroup of group 6) of the Mendeleef periodic table, namely one or more of the oxides of Cr, Mo, W or U.



   The present invention relates to a process for preparing a normally solid hydrocarbon product which comprises, on the one hand, contacting a normally gaseous olefin, chosen from the class consisting of ethylene, propylene, and mixtures containing ethylene and propylene, with an alkali metal and an oxide of a metal of group 6a of the Mendeleef periodic table at a reaction temperature of between about 75 C and about 325 C and, on the other hand, the separation of a normally solid hydrocarbon product thus obtained.



   The present invention relates to: - novel and highly useful catalysts for the preparation of high molecular weight polymers from gas mixtures containing ethylene; - a process for the polymerization of ethylene, in which the yields of solid polymers are considerably increased when compared with the yields which could hitherto be obtained only by the use of sub-hexavalent oxides of the metals of group 6a.



   A novel process for the polymerization of ethylene into normally solid high molecular weight polymers.



   A new process for the conversion of gas mixtures containing predominantly ethylene into solid, resinous or plastic products of high molecular weight.



   A relatively low temperature and relatively low pressure process for converting gases containing ethylene to resinous or high molecular weight plastic products.



   A process for the copolymerization of ethylene with other polymerizable products, particularly with a normally gaseous monoolefin, such as propylene, to prepare new resinous products.



   The aforementioned objects, as well as other objects of the invention, will become apparent during the description which follows.



   Briefly, the process according to the invention consists in converting ethylene mainly into normally solid polymers of high molecular weight, by contacting with an alkali metal and one or more oxides of chromium, molybdenum. , tungsten or uranium, for example a partially reduced molybdenum trioxide extended on a support.



  Although it is preferable to use the alkali metals as they are, it is also possible to use different alloys or compounds analogous to alloys of these alkali metals, for example the various alkali silicides.



   The process according to the invention is carried out at temperatures of between about 75 ° C. and about 325 ° C., preferably between about 130 ° C. and 260 ° C. and at pressures of between about atmospheric pressure and a pressure. relative to 1050 kg / cm2 or more, preferably under relative pressures of between about 14 and 350 kg / cm2, or around 70 kg / cm2. Normally solid products, obtained by catalytic conversion, tend to accumulate on and

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 in the solid catalyst. It is desirable to provide a liquid medium in the reaction zone which serves as both a reaction medium and a solvent for the solid reaction products.

   Suitable liquid reaction media for the polymerization of ethylene include various hydrocarbons, particularly an aromatic hydrocarbon such as benzene, toluene or xylenes. For the polymerization of propylene, less easily alkylatable reaction media are preferred, such as cycloparaffins, such as cyclohexane or decalin, or such as paraffins, such as iso-octane.

   However, the conversion of gas streams containing ethylene or propylene can be carried out in the absence of a liquid reaction medium or a solvent and the catalyst containing solid polymer conversion products which have accumulated can. be treated from time to time inside or outside the conversion zone to extract the conversion products therefrom and, if necessary, to reactivate or regenerate the catalyst for use ulterior.



   The implementation of the process in accordance with the present invention leads to homopolymers of ethylene, to polymers of propylene and to an ethylene propylene copolymer, the molecular weights of which vary in very wide ranges and whose dependent physical and mechanical properties are depending on the choice of operating conditions. The process in accordance with the invention is characterized by extreme flexibility as regards both the operating conditions and the products which can be obtained. Thus, the present process can be carried out over extremely wide temperature and pressure ranges.

   Practice of the present process can result in homopolymers of ethylene having the appearance of grease and having approximate molecular weights of between 300 and 700, homopolymers of ethylene having the appearance of fat. wax and having an approximate specific viscosity (x105) of between about 1,000 and 100,000, and to hard and resinous homopolymers of ethylene having an approximate specific viscosity (x10) of 10,000 to over 300,000 /.

   0 relative - 1 x 105 J. By the term "resinous hard polyethylene" used in the present description and in the claims, is meant a polymer having a point of brittleness less than -50 ° C (method ASTM D746-51T), an impact strength greater than 0.275 mx. kg per 2.5 cm notch (ASTM D256-47T method on an Izod machine) and a minimum elongation at laboratory temperature (25 C) of 100%. (A.S.T.M .: Association for Testing Material) o
The process according to the present invention can be used to carry out the copolymerization of ethylene with other polymerizable products, and particularly with propylene.

   The propylene alone was also polymerized by using the catalysts in accordance with the present invention in order to convert it into a solid polymer. Other polymerizable products include mono-olefinic hydrocarbons, such as normal butylene, iso-butylene, tert-butyl-ethylene, etc., usually in amounts between about 1 and about 25% by weight per weight. relative to the weight of ethylene.



   An important characteristic of the present invention is the simultaneous use of a catalyst constituted by the oxide of a metal of group 6a and of an alkali metal, for example lithium, sodium, potassium, rubidium. or cesium. Mixtures of the alkali metals, for example sodium-potassium eutectic or alloys containing alkali metals, can be used. The use of an alkali metal in the reaction zone has many important practical consequences over the processes in which said metal oxide catalysts are used without alkali metals.

   Thus, in the presence of both alkali metal and metal oxide catalysts, high yields of po-

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   solid polymers from ethylene, the metal oxide catalyst being able to act effectively in the presence of high proportions of a reaction medium liquidating the metal oxide catalyst retains high polymerizing activity for a long period of time (long duration). catalyst life), and polymers having physical and chemical properties within desired ranges can be easily prepared by controlling reaction variables, etc., as will become apparent from the detailed description and operational examples which follow.



   The function or functions of the alkali metal in the process according to the invention are not well understood. Alkali metals alone are not catalysts for the polymerization of ethylene or propylene to give normally solid high molecular weight polymers under the conditions mentioned in this specification. the alkali metals promote the action of group 6a metal oxide catalysts to increase the productivity (polymer yield) of these catalysts sometimes in a prodigious manner.

   One might assume that the alkali metals act simply by reacting with poisons in the catalyst which might be present in small amounts, on the order of a few parts per million in ethylene, propylene and / or in the medium. liquid reaction; however, Applicants have found that even extremely pure ethylene or propylene and a liquid reaction medium which have been contacted with an alkali metal under the reaction conditions and which have immediately thereafter been put into contact with an alkali metal. Tact, in a separate zone, with a molybdenum oxide catalyst does not produce solid polymer with the high yields or good quality which can be obtained by the process according to the present invention.



   The Applicant has further observed that the alkali metal activates the molybdenum oxide catalyst so much that, to the knowledge of the Applicant, it has made it possible, for the first time, to the knowledge of the Applicant, to obtain solid polymers by contacting ethylene with MoO3 alone, that is, without a support to greatly increase the surface area over which the MoO3 is spread.

   Another surprising and unexpected effect is that ethylene can be converted to normally solid polymers by contacting it with an alkali metal and a solid oxide catalyst in which the metal of group 6a is present initially. as a tri-oxide rather than a syb-hexavalent oxide of the Group 6a metal, which is essential when no alkali metal is used in the reaction zone. Prior to the present invention, it was known that the sub-hexavalent molybdenum oxides were catalysts for the polymerization of ethylene to give normally solid polymers only when supported on the three hardly reducible metal oxides: alumina. gamma, titanium oxide, zirconia.

   In the presence of alkali metals, Group 6a metal oxide catalysts can be used not only on alumina, titanium oxide or zirconia supports, but also on a wide variety of other supports for the polymerization of metal. ethylene and / or propylene to form normally solid polymers, for example on silica supports, such as silica gel, kieselguhr, diatomaceous earth; lasilica-alumina, aluminosilicates, such as various clays and bleaching earths; and even on absorbent carbon, which is however not preferred.

   In the practical process, it is preferable to provide a hardly reducible metal oxide for the group 6a metal oxide catalyst, for example gamma alumina.

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 EMI4.1
 king-0 The proportion of alkali metal used can vary between about 0.001 and about 2 parts by weight per part by weight of catalyst
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 metal oxide (total weight of solid catalyst). The activity of tauy, in promoting the reaction of metaoys, increases with increasing atomic weight.

   One can easily determine, in the particular cases, the optimum proportions by simple tests on a reduced scale with the particular charges, the liquid reaction medium, the reaction medium / catalyst ratio, the nature of the catalyst, the temperature and the nature of the product you want. Generally, sodium is used in proportions of from about 0.01 to about 2 parts by weight per part by weight of molybdenum catalyst with ratios of from about 5 to about 3,000 volumes, or more, of liquid medium per part.
 EMI4.3
 part by weight of metal oxide catalyst.



   The relative proportions of the support to the metal oxide catalyst are not critical and can be varied over a relatively wide range such that each component is present in an amount of at least about 1% by weight. The usual oyyde ratios
 EMI4.4
 metal / support are between approximately 1:20 and 1.1 or approximately lsl0o The Applicant uses metal oxide catalysts on conditioned alumina, consisting of an alumina-gamma base. containing in-
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 about 1 to 8%, preferably about 5 to 35%, or about 10, of a catalytic metal oxide supported by this base.



   The supports consisting of alumina-gamma, titanium oxide and zirconia for the catalysts in accordance with the invention can be prepared in any known manner and, likewise, it is possible to incorporate into the support or deposit on the support. in any known manner oxides
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 of molybdenum or of another metal of group 6ao d9-e'YCellent results have been obtained with molybdic anhydride-alumina, chromalumina oxide and tungstic anhydride-alumina catalysts which can be catalysts of
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 type used for performing hydroforming, the word hydroforming "being used to represent processes of the type described in
 EMI4.8
 U.S. Patents Nos. 2,320,147 of September 13, 1939, 203,536 of July 26, 1940, 2a357a332 of March 30, 1940, etc.



   Molybdic anhydride or other oxygenated compounds of molybdenum, such as cobalt molybdate, can - be incorporated into the
 EMI4.9
 base of the catalyst in any known manner, by ereoeple by impregnation, co-precipitation, co-formation of a gel, and / or absorption, and the base of the catalyst and / or the catalyst in the final state can be stabilized by heat by any of the known methods heretofore used in the preparation of hydroforming or hydrofiningo catalysts. Cobalt molybdate catalysts can be prepared as described in US Patents.
 EMI4.10
 United States of America n.2393.288 of July 6, 1943, 204860361 of October 20, 1944, etc ...

   It is also possible to use cobalt, calcium, nickel and copper salts, chromic, tungstic and uranic acids, with or without a support.



   The catalyst can be stabilized by silica (U.S. Patents 204370532 of August 8, 1944 and 204370533 of August 8, 1944) or by aluminum orthophosphate (U.S. Patents
 EMI4.11
 No. 2ott, 0o236 resulting from two patent applications filed on May 3, 1944 and February 12, 1946, and 2,441,297 on May 3, 1944) or by other known stabilizers or modifiers.

   The catalyst may contain 1.51 ode of calcium (US Patents 2,422,172 of July 28, 1942 and 2,447,043 of August 24, 1944) or the base may consist of
 EMI4.12
 zinc aluminate spinel (US Pat. No. 2oltl, 70016 of March 2, 1948) and may contain appreciable amounts of zirconia or titanium omide (US Pat. rique n 204370531 due 24 December 1942 and 204370532 dated 8 August 1944).

   Oyides of other metals, such as magnesium, nickel, zinc, vanadium, thorium, iron, etc., may be present in smaller amounts, less than 10% by weight.

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 total catalyst weight,
Although, as mentioned above, there is no need to reduce the metal oxide catalysts when they are used in the presence of an alkali metal, it is preferable in the industrial process to carry out a reduction or conditioning treatment.

   The conditioning or reduction treatment of the oxide of the hexavalent metal of group 6a is preferably carried out by means of hydrogen, although other reducing agents, such as carbon monoxide, carbon monoxide, mixtures of hydrogen and carbon monoxide (water gas, air gas, etc ...), sulfur dioxide, hydrogen sulphide, dehydrogenatable hydrocarbons, etc ..., can be used. Hydrogen can be used as a reducing agent at temperatures between about 350 ° C and about 8500 ° C, although temperatures between 450 and 650 ° C are more often used.

   The partial pressure of hydrogen in the reducing or conditioning operation can be varied from pressures below atmospheric pressure, for example as low as 0.007 kg / cm (absolute pressure) to relatively low pressures. The simplest reduction operation can be carried out with hydrogen simply at a pressure close to atmospheric pressure, up to 210 kg / cm2 or even more.



   The partial reduction of the metal oxide catalyst in which the metal is present in its hexavalent condition can be carried out in the presence of the alkaline activator or promoter before contacting the combination of catalysts with ethylene. The Applicant has sometimes found that it is possible to eliminate or substantially reduce a period of induction before the polymerization of ethylene by sending hydrogen under pressure into the reactor containing the solvent, the ethylene, the catalyst. - metal oxide and alkali metals, for example under relative hydrogen pressures of between about 0.7 and about 63 kg / cm2, preferably 7 to 28 kg / cm2; under these conditions, a small proportion of the ethylene is reduced to ethane.



   Lithium aluminum hydride, an exceptionally active reducing agent, conditions and activates catalysts containing oxides of a Group 6a metal in the hexavalent state and at temperatures as low as 35 ° C, although In general, temperatures of between about 100 and about 300 ° C are used. In practice, for example, a catalyst containing free or chemically combined MoO3 (eg combined in the compound Como04) is treated with a suspension of LiAlH4 in a liquid hydrocarbon solvent with ratios of from about 0.01 to about 1 part in. weight of LialH4 per part by weight of solid catalyst.

   Sodium hydride (or sodium and molecular hydrogen) is effective in reducing and conditioning Group 6a metal oxide catalysts in the hexavalent state, such as MoO3, at temperatures greater than about 1800C and can be used in the same proportions as LiAlH4.



   The conditioning and reduction treatment of the oxide of the metal of group 6a can be followed and controlled by analysis with a solution of sulfuric acid and ceric sulphate, which makes it possible to determine in a manner specifies the average valence in the catalyst of the oxide of molybdenum or another metal. When determining the average valency of metals, such as molybdenum, in catalysts such as partially reduced MoO3 supported on hard-reducing metal oxides, such as gamma-alumina, it is necessary to consider know the total molybdenum content and the number of milli-equivalents of a standard oxidizing reagent required to reoxidize partial molybdic anhydride to Mo03

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 reduced.

   A suitable oxidation process is to weigh approximately 1gr of finely ground and freshly reduced catalyst into a 250 cc glass-top Erlenmeyer flask and add 25 cc of a decinormal solution of ceric sulfate and 25 cc of sulfuric acid 1: 1. This mixture is stored at laboratory temperature for four days with frequent stirring. This time was originally chosen in an arbitrary manner, but was later found to be more than sufficient for oxidation to take place. The solid residue is then separated by filtration and the excess of ceric solution is determined by the addition of an excess of standard ferrous solution which is, in turn, titrated with a standard ceric solution, using as indicator the orthophenanthroline error. .

   The total molybdenum in the sample is determined by dissolving this sample in a solution of sulfuric acid and phosphoric acid, the molybdenum is reduced in a Jones reducing agent, the solution reduced in ferric alum is absorbed and titrated. resulting ferrous ion with a standard ceric sulfate solution. The oxidation state of molybdenum can be determined from the values obtained. -
The partial reduction of molybdenum oyide or other trioyide of a Group 6a metal is carried out to such an extent that the average valence state of the catalytic metal in the catalyst is between about 5.5 and about 2, preferably between about 3.0 and about 5.0.



   The conditioning treatment described above is required not only for the fresh catalyst, but also for the catalyst which has become relatively inactive in the polymerization process. As will be described below, the polymer formed in the polymerization reaction should be continuously or intermittently removed from the catalyst particles, preferably by means of solvents, and it is generally necessary or desirable to condition the surface of the catalyst. catalyst which has thus been liberated to some degree of the polymer before it can be used again to effect polymerization.

   When it is no longer possible to make the catalyst sufficiently active by simply removing the polymer and conditioning with a reducing gas, as described above, it can be regenerated by extraction with water, with ammonium salts. or with dilute aqueous acids, with subsequent combustion of the combustible deposits which are on it by means of oxide, this combustion being followed by the conditioning operation o Detoxification of the catalysts can be carried out by treatment with dilute aqueous solutions of per-acids , such as permolybdic, pervanadic or pertungstic acids, followed by hydrogen conditioning of the catalysts.



   The catalysts can be used in various sizes, for example in the form of powder, granules, micro-spheres, filter cake fragments, lumps or pellets having a determined configuration. A suitable form in which the catalysts can be used are granules the size of which is approximately between 8 and 40 meshes / cm.



   The raw material for the polymerization process according to the present invention preferably comprises essentially ethylene.



  Ethylene-based feeds can contain hydrogen and hydrocarbons as in refinery gas streams, for example methane, ethane, propane, etc. However, it is preferable to use feeds of ethylene as pure and concentrated as it is possible to obtain.



  When the feeds contain propylene as well as ethylene, these two olefins can contribute to obtaining resinous products of high molecular weight.

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 It is desirable to minimize or avoid the introduction of oxygen, carbon dioxide, water or sulfur compounds in contact with the catalyst.



   In general, the polymerization according to the process according to the invention can be carried out at temperatures between about 75 ° C. and about 325 ° C. The polymerization in the present process is generally carried out at temperatures between about 110 and about. 275 C or in the preferred narrower range limited by about 220 to about 260 Ce The use of polymerization temperatures of from about 230 to about 260 C and a liquid hydrocarbon reaction medium, such as benzene, xylenes, decalin, or methyl decalines, are highly desirable to produce polymers of ethylene having specific viscosities (y 105)

     averaging between about 10,000 and about 300,000 in continuous operations with relatively long operating times and active catalysts.



   It has been found that the process according to the present invention can be used for the production at relatively low temperatures of ethylene heteropolymers and homopolymers having relatively high molecular weights. The process of the present invention can be carried out to some extent even at atmospheric pressure.

   The upper limit of the relative partial pressure of ethylene in the process is dictated by economic considerations and by equipment limitations and can be 700 kg / cm2, 1400 kg / cm2 or even more. relative economically desirable ethylene ranges from about 14 to about 350 kg / cm2, preferably from about 35 to about 105 kg / cm2. for example about 70 kg / cm2.



   The contact time or volumetric rate used in the polymerization process is chosen according to the other process variables, the catalysts, the particular type of product desired and the extent of ethylene conversion desired for any given passage through. the catalyst.

   In general, this variable can be easily adjusted to obtain the desired results.
In operations where the ethylene feed must flow continuously to come into contact with the solid catalyst and thereafter to leave that contact, suitable hourly volumetric rates for the liquid are usually from about 0.1 to about 10. volumes, preferably about 0.5 to about 5, or about 2 volumes of ethylene solution in a liquid reaction medium which is usually an aromatic hydrocarbon, such as benzene, xylenes or tetralin, or a cycloaliphatic hydrocarbon, such as decalin (decahydronaphthalene).

   The amount of ethylene in such solutions can range from about 2 to about 50% by weight, preferably from about 2 to about 10% by weight or, for example, from about 5 to 10% by weight. The Applicant has found that when the concentration of ethylene in the liquid reaction medium is reduced to a value less than 2% by weight, the molecular weight and the viscosity at the time of melting of the polymer products drop suddenly. The rate of polymerization of ethylene tends to decrease with increasing concentration of ethylene in the liquid reaction medium.

   However, the rate of polymerization of ethylene to form normally solid high molecular weight polymers should not be such that such solid polymers are formed in amounts which substantially exceed the solubility thereof in said medium. liquid reaction under operating conditions, usually up to about 5-7% by weight, not including the amounts of polymeric products which are selectively adsorbed by the catalyst.

   Although ethylene concentrations exceeding 10% by weight in the medium can be used.

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 reaction liqud, solutions of ethylene polymer in the reaction medium exceeding 5 to 10% become very viscous and unwieldy and cracking where severe stripping of particles or fragments of solid metal oxide catalyst may occur, which can result in severe stripping of particles or fragments of solid metal oxide catalyst. which has the effect that the catalyst is entrained as fines with the solution of the polymerization products and a subsequent significant loss of the catalyst from the reactor.



   In batch operations (in separate batches), operating periods of between about half an hour, and about 10 hours, preferably between about 1 and about 4 hours, are used and the autoclave where the reaction takes place is charged. with ethylene as the pressure drops as a result of the ethylene conversion reaction.

   The solvent / catalyst weight ratio can be varied in the range of about 5 to about 3000, or even more for continuous flow systems (continuous operation) o The use of very high solvent / catalyst ratios, which is possible by the presence of an alkali metal in the reaction zone, is very important to obtain high yields of polymer.
Ethylene can be polymerized in the gas phase and in the absence of a liquid reaction medium by contacting an alkali metal and Group 6a metal oxide catalysts.

   When the desired polymerization reaction is complete, it is then possible to treat the solid catalyst to extract the solid polymerization products, for example by extraction with suitable solvents, however, to obtain increased ethylene conversion rates and to obtain higher ethylene conversion rates. To continuously extract the solid conversion products from the catalyst, it is desirable to effect the conversion of ethylene in the presence of suitable liquid reaction media.

   The liquid reaction medium can also be used as a means of contacting ethylene with the catalyst by preparing an ethylene solution in the liquid reaction medium and contacting the resulting solution with the polymerization catalyst. Reaction liquid works as a solvent to remove some of the normally solid product from the catalyst surface.

   Different classes of hydrocarbons or their mixtures can be used which are liquid and substantially inert under the conditions of the polymerization reaction according to the present process. Members of the aromatic hydrocarbon series can be used, particularly the mono-nuclear aromatic hydrocarbons. , for example benzene, toluene, xylene, mesitylene, and -sylene-p-cymene mixtures.



  It is also possible to use tetrahydronaphthalene. In addition, aromatic carbides can be used, such as ethylbenzene, isopropylbenzene, n-propylbenzene, sec-butylbenzene, tert-butylbenzene, ethyltoluenes, ethyllyylenes, hemimellitene, pseudocumene, phrenitene, isodurene, diethylbenzenes, isoamylbenzene, etcooo - Suitable aromatic hydrocarbon fractions can be obtained by selective extraction of aromatic naphtha, from hydroforming operations in the form of distillates or still bottoms, from fractions of recycling feedstock from cracking operations, etc ...



   It is also possible to use certain alkyl naphthalenes which are liquid under the conditions of the polymerization reaction, for example 1-methylnaphthalene, 2-isopropylnaphthalene, 1-n-amylnaphthalene, etc., or fractions obtained industrially and containing these hydrocarbons.



  Certain classes of aliphatic hydrocarbons can also be used as the liquid hydrocarbon reaction medium in the present process. Thus, various saturated hydrocarbons (alkanes and cycloalkanes) which are liquid under the conditions of the reaction can be used o Either alkanes or cycloalkanes can be used pure or industrially available mixtures free of poisons for the catalyst. For example, naphthas or straight-run kerosines containing al-.

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 kanes and cycloalkanes.

   Particularly, liquid or liquefied alkanes can be used, such as n-pentane, n-hexane, 2,3-dimethyl-butane, n-octane, liso-octane (2,2,4-trimethylpentane ), n-decane, n-dodecane, cyclohexane, methylcyclohexane, dimethylcyclopentane, ethylcyclohexane, decalin, methyldecalines, dimethyldecalines, etc ...



   It is also possible to use a liquid hydrocarbon reaction medium comprising liquid olefins, for example n-hexenes, cycloheven, 1-octane, heyadecenes, and so on.
The normally solid polymerization products which are retained on the surface of the catalyst or the polymers of ethylene having the appearance of a fat may themselves play the role at some degree of reaction medium. liquid hydrocarbon, but it is highly desirable to add thereto in the reaction zone a viscosity reducing hydrocarbon, such as those mentioned above.



   The liquid hydrocarbon reaction medium must be freed of poisons by acid treatment, for example anhydrous p-toluenesulphonic acid, sulfuric acid or by equivalent treatments, for example with aluminum halides or other Friedel-Grafts catalysts, maleic anhydride, calcium, calcium hydride, sodium or other alkali metals, alkali metal hydrides, lithium aluminum hydride, l 'hydrogen and hydrogenation catalysts (hydrofining), by means of filtration through a column of copper filings or of a group 8 metal,

       etc ... or by combining such treatments
The Applicant has purified chemically pure pylons by reflux treatment with a mixture of catalyst No03-A1203 and LiAlH4 (50cm3 of yylene - 1 g of catalyst - 0.2 g of LiA1H4) at atmospheric pressure, operation followed by a distillation of yylenes. A further more efficient purification of the solvent can be achieved by heating it to about 225-250 ° C with either sodium and hydrogen or NaH in a pressure vessel.



   Temperature control can be easily achieved during the ethylene conversion process by the presence in the reaction zone of a large liquid mass having a relatively high heat capacity. liquid hydrocarbon reaction medium by heat exchange inside or outside the reaction zone It should be noted, however, that in some cases the solvent may be present as a phase consisting of by denseo gas
When using solvents such as xylenes, some alkylation thereof by ethylene may occur under the conditions of the reaction. Propylene is a much more reactive alkylating agent than ethylene and when propylene is present in the load,

   it is desirable to use a non-alkylatable solvent, such as decalin.



  The alkylate is removed with grease in the process according to the present. invention; it can be separated from the fat by fractional distillation and, if desired, it can be returned to the polymerization zone.
There is shown in the accompanying drawing a flow diagram given by way of example, indicating a method for carrying out the invention.
The olefinic feed, consisting of ethylene or an ethylene-propylene mixture, is passed through a compressor 10 in which the pressure of the feed is brought to a suitable value, for example between 35 and 140 kg / cm2;

   from there, the charge passes into chamber 11 which

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 is provided with a suitable de-oxygenating agent, such as metallic copper at 150 G, then in chamber 12 which is provided with a dehydrating reagent, such as adsorbent alumina, anhydrous calcium sulfate, silica gel, or equivalent drying reagents. The dried feed is passed from chamber 12 into chamber 13 where carbon dioxide is removed from the feed. The chamber 13 comprises a suitable reagent, for example caustic soda deposited on asbestos, or any other effective decarbonation reagent. The load can then be dried again if necessary after it leaves chamber 13.

   The feed thus purified usually contains less than 50 parts of oxygen per million and has a dew point of less than -45 ° C. The purified feed then arrives in an absorber 14 where it meets the solvent against the current. The solvent or the liquid reaction medium can be introduced into the absorber and into the circulation scheme by the pump 15 through the pipe 16 provided with a valve and the heat exchanger 17 in which it is brought to. a suitable temperature for absorption, generally between about 15 and about 35 ° C, although higher or lower temperatures can be used.



   Recycle solvent from line 61 can also be sent to the absorber, or this recycle solvent can be used as the sole absorption medium. In the absorber 14, a solution is formed containing between 2 and about 30% of olefin, for example 7% by weight of ethylene, and this solution is withdrawn by means of line 18 provided with a valve to convey it. in a holding chamber 19 for final purification o The holding chamber may contain an active metal or a metal hydride, for example sodium or another alkali metal, @ an alkaline earth metal, an alkali hydride or an alkaline earth hydride .



    Calcium hydrate is a preferred product for use in the holding chamber. The retaining chamber can operate at temperatures between about 1000C and about 280C. If the charge is of sufficient purity, it is possible to avoid passing through the retaining chamber (by pipelines not shown) and introducing the charge directly into the chamber. reactor 25.



   The ethylene and the solvent are discharged from the holding chamber 19 into the pipe 20 and, from there, thanks to the pump 21, they reach the heater 22 in which they are brought to the polymerization temperature included, for example, between about 200 and about 275 Co From heater 22, the charge passes through line 23 and from there through line 24 arrives at the bottom of reaction chamber 250 While a certain amount can be used number of suitable reactors, there is shown in the accompanying drawing an autoclave divided into an upper part and a lower part by means of a partition 26. A stirrer device 27 projects into the lower part of the reactor and suitable partitions 28 are arranged. on the walls.

   The stirring mechanism can rotate at speeds between about 20 and about 1000 revolutions per minute, for example 650 revolutions per minute. It is seen, therefore, that a very intimate mixture between the catalyst, the alkali metal, the olefinic product and the liquid reaction medium is carried out in the lower part of the reactor 25. The reactor 25 may be initially charged with a Group 6a metal oxide catalyst and with alkali metal through interlocked hopper devices or equivalent devices and additional amounts of metal oxide catalyst and alkali metal may be added intermittently during of the reaction, as desired, by suitable means.



   If desired, a fraction of the pre-dried solvent can be passed through the pipe 29 provided with a valve and the heater 30, in which this fraction is brought to a temperature between about 150 C and about 300 C, in a contacting chamber 31 for

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 view of a partition 32, of a stirring device 33 and of an inlet 34 for the alkali metal A dispersion or: intimate solution of alkali metal in the solvent is produced in the contacting chamber 31 and is withdrawn this dispersion or solution from the upper relatively calm zone of the chamber 31 by means of a pipe 35 provided with a valve to bring it into the pipe 24 and discharge it by a pump 36 into the reactor
25.

   A very interesting method and constituting a variant of the above method for purifying the solvent in the contacting chamber 31 is to treat this solvent with an alkali hydride, generally NaH, and an oxide of a metal of the metal. group-6a on a support, for example 10% by weight of MoO3 on gamma-alumina using about 3 to about 10 parts by weight of metal oxide on a support per part by weight of hydride of alkali metal, at a temperature between approximately
135 and about 270 C and at hourly volumetric liquid velocities between about 0.5 and about 10.



   In reactor 25, the polymerization of ethylene or the copolymerization of ethylene with other products is carried out to give polymers such as propylene and at suitable temperatures and pressures. The usual concentration of ethylene in the reactor is carried out. solvent entering the reactor is about 10% by weight and the product leaving the reactor generally consists of a 2-5% by weight solution of solid polymer in the solvent. When it is desired to prepare a homopolymer of the solvent. ethylene having a viscosity at the time of melting of between about 2 x 105 and about 5 y 106 poises,

   preferred temperatures are from about 230 to about 2750 The reaction period can be varied from about 10 to about 100 minutes.
It is understood that instead of using a reactor, it is possible to use several reactors arranged in parallel or in series.

   When using reactors in series, variations in temperature and pressure, in olefin concentration in the solvent and in catalyst concentration become possible, so that greater control can be exerted on the reactor. average molecular weight and the range of molecular weights of the product, as well as the extent of conversion in each stage. Likewise, it is possible, by the use of a number of line branched reactors, to and suitable valves, to shut down any reactor in the device to allow cleaning and repair.
The upper part of the reactor 25 constitutes a calm settling zone,

   in which the fine particles of catalyst and alkali metal settle out of the solution of the polymer product in the reaction solvent and return, under the effect of gravity, to the agitated lower zone of the reactor o The relatively clear solution of the products of The reaction in the solvent is withdrawn from the upper part of the reactor 25 through line 37 and the expansion valve 38 in which the relative pressure can drop to a value between about 1 and about 17.5 kg / cm 2.

   The mixture constituting the product obtained leaves the valve 38 tangentially to reach the separator, for example a cyclone separator 39, in which a temperature of at least 150 Co is maintained. The separator 39 is withdrawn via the pipe 40 fitted with a valve. , gas comprising a significant proportion of ethylene without inclusion of poison Solvent can be introduced at high temperature into separator 39 through line 51 to prevent the separation of the polymer on the walls of the separator o It is withdrawn from separator 39, through line 41 'with a valve, the polymer solution in the solvent (maximum percentage of polymer close to 5% by weight)

   to direct it towards the filter 42 thanks to which all the fine particles of catalyst which could be entrained are separated and withdrawn by the pipe 43 provided with a valve. If desired, the polymer solution can be subjected to the ac-

 <Desc / Clms Page number 12>

 tion of ultrasonic vibrations which effect the coagulation of the very fine particles of catalyst, so that they can be easily filtered.



   The polymeric product solution is withdrawn from filter 42, through line 44, into condenser 45, where its temperature is brought to a value between about 90 ° C and about 20 ° C, and is removed. then sends, through line 46, to filter 47. The solid polymer product is removed from filter 47 at 48 and the solvent or reaction medium is withdrawn through line 49 from where a portion can be discharged from the device by the pipe 50 provided with a valve, another portion can arrive, through the pipe 51 provided with a valve, the pump 52 and the heater 53, in the separator 39 and the remainder can be brought, by a pipe 54 provided with a valve, in the fractionation device 55.



   The polymer can be induced to precipitate from solution in line 44 by the addition of anti-solvents, such as low-boiling hydrocarbons, such as propane, alcohols, ketones (acetone), etc. The polymeric product of the present process, which was removed at 48, can be subjected to various treatments to prepare it for conversion into a finished industrial product. Thus, it can be subjected to different treatments to remove the solvent which imbibes it, it can be shredded or extruded to form particles in the form of laces, it can be dried, etc.



   In the fractionator 55, the solvent or the liquid reaction medium is vaporized and exits at the top through the line 56; from this pipe, a fraction of the solvent can be removed from the device through the pipe 57 provided with a valve, but it preferably passes, through the pipe 58 fitted with a valve, into a condenser 59, in which its temperature is brought to a value between approximately 20 C and approximately 80 C, from where it arrives in a pump 60. The pump 60 delivers the solvent through the pipe 61 provided with a valve and the heat exchanger 17 to send it to absorber 14 to prepare a solution of the fresh ethylene feed for the polymerization process.



  A portion of the solvent is also delivered by the pump 60 in the pipe 62 provided with a valve to reach the upper part of the absorber 63o The recycled gases from the separator 39 and from the pipe 40 follow a pipe 64 fitted with a valve, pass through a compressor 65 and reach, through a pipe 66, the lower part of the absorber 63 in which the ethylene is selectively absorbed in the solvent to produce a solution having a concentration of between about 2 and about 10% by weight of ethylene,

   which is withdrawn from the absorber 63 by the pipe 67 fitted with a valve to reach the pipe 20 through which it arrives at the reactor 25 The unabsorbed gases are evacuated from the absorber 63 by the pipe 68 fitted with a valve
Liquid reaction products having the distillation range of the solvent medium can be discharged from the fractionator 55 and the process through line 69 with a valve, but are preferably delivered through the valve. pipe 70 provided with a valve, in a second fractionation device 71.

   A by-product generated in a relatively small volume in the polymerization process object of the present invention, when an alkylatable aromatic hydrocarbon, such as xylene, is used as the solvent, is constituted by a. alkylate produced by the reaction of said alkylatable aromatic hydrocarbon and ethylene (or propylene when the latter is used as a component of the feed) o The alkylated aromatic hydrocarbon products are vaporized and fractionated in tower 71 and they are discharged from this turn through line 72. It is generally desirable to recycle at least a fraction of the alkylate through line 73 provided with a valve to line 41 for its use as a solvent on filter 42.

 <Desc / Clms Page number 13>

 



   The remainder of the alkylate can be removed from the process through line 74 fitted with a valve, or it can be recycled, for use as a partial component of the liquid reaction medium, in reactor 25.



   Relatively low proportions of low molecular weight, fat-like polymers of ethylene are produced in the polymerization process. The products having the appearance of a grease are withdrawn in the form of bottom fractions of the tower 71 by the line 75 provided with a valve.



   A variant of the operating process consists, following the filtration of the fine catalyst particles on the filter 42, in introducing the dilute solution of ethylene polymers in the reaction solvent, for example benzene, in a tower containing boiling water or a mixture of liquid water and vapor at temperatures sufficient to instantaneously distill the solvent (or an azeotrope of solvent and water) from the solution and to produce an aqueous slurry of the polymer solid containing from about 1 to about 5% by weight of polymer.

   The aqueous polymer slurry can be concentrated by the usual procedures to obtain a paste containing about 10 to 15% polymer, which can then be centrifuged to give a polymer containing a lower fraction of water and which can be dried completely. in usual equipment. The solvent going overhead in the flash distillation operation can be condensed, separated from a liquid bottom layer of water, redistilled to dry again and finally it can be completely dried with desiccators, such as silica gel. or alumina gel, before recycling to storage or to the polymerization reaction zone.



     Some non-limiting examples will now be given to illustrate the present invention. Unless otherwise indicated, the general process which was used in batch operations was as follows: the catalyst had dimensions corresponding to sieves of 8-34 mesh / cm, and it had 8% by weight of MoO3 on an alumina-gamma support * The molybdic anhydride catalyst having been pre-reduced unless otherwise indicated. The pre-reduction of the molybdic anhydride catalyst was carried out by means of dry hydrogen at atmospheric pressure passing through the catalyst with a flow rate of around 5 liters per hour for 1 to 10 g of catalyst and this for 16 hours at 480. vs.



  The reactions were carried out in a pressure vessel having a capacity of 100 cc and provided with a magnetically controlled stirring device. The reactor was charged with 50 cc of slovant and then with pre-reduced molybdic anhydride catalyst. When 100 cc of solvent was used, a 250 cc autoclave was used. The free space for gases in the reactor was then filled with nitrogen.

   The alkali metal in particulate form was then added to the reaction vessel, and the cover was disposed while maintaining a stream of nitrogen to ensure the absence of air in the apparatus. When unreduced catalyst was loaded into the reaction vessel, it was simply poured without using nitrogen. Residual air was removed from the reaction vessel during pressure withstand tests with hydrogen. The final component, ethylene, was charged to the reaction vessel after the latter was heated to the reaction temperature. The magnetically driven stirrup stirring device was alternately lifted and dipped through the solution at a rate sufficient to maintain the catalyst in suspension.

   Ethylene was introduced from time to time during the operation in order to maintain the reaction pressure. It is possible to superimpose on the ethylene pressure a lower partial pressure of hydrogen, of the order of about 7 to 14 kg / cm2 (relative pressure) when the reaction

 <Desc / Clms Page number 14>

 tion does not start easily The po @ grès of an opera- tion under pressure can be obtained by plotting the sum of the times in abeissas and the sum of the pressures in ordinates. In many cases, we could have obtained much higher yields. high if it had been arranged to introduce a greater proportion of solvents into the reaction zone,

   since one of the reasons for terminating an operation was the blockage of the agitation device due to the formation of a high molecular weight polymer in the reaction zone in an amount exceeding its solubility in the liquid reaction medium under the reaction conditions.



   The important influences of the alkali metal promoters according to the invention will be better appreciated if the following are taken into account. In operations carried out without any promoter, using the operating method which has just been described and using the catalyst with 8% molybdenum oxide 1 reduced on alumina-gamma and a chemically pure xylenes / catalyst ratio of 5 cm / g, only 0.5 g of solid ethylene polymer was obtained per gram of catalyst at 230 ° C. and under an initial relative ethylene pressure of 70 kg / cm 2.



   Alkali metal promoters allow the use of very high solvent / catalyst ratios, while maintaining relatively high polymerization rates which in turn ensure continuous process and long catalyst life, and which also result in relatively high polymerization rates. The result is much higher solid polyethylene yields for the same weight of metal oxide catalyst used.



    BOARD.
 EMI14.1
 
<tb>
<tb>



  Exem- <SEP> Cataly- <SEP> Metal <SEP> al- <SEP> Tempera- <SEP> Pressure <SEP> Solvent <SEP> Efficiency <SEP> in <SEP> polyple <SEP> sor <SEP> calin < SEP> gr. <SEP> ture <SEP> C <SEP> relative <SEP> cm3 <SEP> mother <SEP> solid <SEP> grs / gr
<tb> gr. <SEP> (1) <SEP> (2) <SEP> in <SEP> kg / cm2 <SEP> (4) <SEP> of <SEP> catalyst <SEP> so-
<tb> (3) <SEP> read
<tb> 1 <SEP> 0.5 <SEP> 0.5 <SEP> 230 <SEP> 71 <SEP> 150X <SEP> 7.1
<tb> 2 <SEP> 1 <SEP> 0.5 <SEP> 230 <SEP> 70 <SEP> 140X <SEP> 6, <SEP> 66 <SEP>
<tb> 3 <SEP> 0.1 <SEP> 0.1 <SEP> 230 <SEP> 70 <SEP> 50X <SEP> 6.7
<tb> 4 <SEP> 0.1 <SEP> 0.1 <SEP> 233 <SEP> 75 <SEP> 100X <SEP> 49.6
<tb> 5 <SEP> 0.1 <SEP> 0.1 <SEP> 232 <SEP> 49/27 <SEP> 100X <SEP> 51.8
<tb> 6 <SEP> 0.5 <SEP> 0.2 <SEP> 230 <SEP> 35 <SEP> 100X <SEP> 8.6
<tb> 7 <SEP> 3.0 <SEP> 0.3 <SEP> 180 <SEP> 17 / 5.6 <SEP> 150X <SEP> 1.06
<tb> 8 <SEP> 1.0 <SEP> 0,

  1 <SEP> 277 <SEP> 70/7 <SEP> 50D <SEP> 5.85
<tb> 9 <SEP> 1.0 <SEP> 0.1 <SEP> 255 <SEP> 67.5 / 7 <SEP> 100D <SEP> 6
<tb> 10 <SEP> 1.0 <SEP> 0.1 <SEP> 325 <SEP> 66.5 / 8 <SEP> 100D <SEP> 7.3
<tb> 11 <SEP> 1.0 <SEP> 0.1 <SEP> 283 <SEP> 56/7 <SEP> 50X <SEP> 4.25
<tb> 12 <SEP> 1.0 <SEP> 0.1 <SEP> 275 <SEP> 43.5 / 31 <SEP> 50B <SEP> 7.0
<tb> 13 <SEP> 1.0 <SEP> 0.1 <SEP> 276-282 <SEP> 35/39 <SEP> 50B <SEP> 4.6
<tb> 14 <SEP> 1.0 <SEP> 0.05 <SEP> 255 <SEP> 65/9 <SEP> 50X <SEP> 5.36
<tb> 15 <SEP> 1.0 <SEP> 0.1 <SEP> 270 <SEP> 67 / 5.6 <SEP> 100T <SEP> 6.36
<tb> 16 <SEP> 1.0 <SEP> 0.1 <SEP> 232 <SEP> 66/6 <SEP> 50X <SEP> 2.28
<tb> 17 <SEP> 1.0 <SEP> 0.1 <SEP> 232 <SEP> 65/7 <SEP> 95X <SEP> 4.38
<tb> 18 <SEP> 1.0 <SEP> 0.1 <SEP> 233 <SEP> 60/11 <SEP> 45X <SEP> 4.02
<tb>
 

 <Desc / Clms Page number 15>

 BOARD. (after) .
 EMI15.1
 
<tb>
<tb>



  Exem- <SEP> Catalyst <SEP> Metal <SEP> al- <SEP> Temp- <SEP> Pressure <SEP> Solvent <SEP> Efficiency <SEP> in
<tb> ple <SEP> gr. <SEP> (1) <SEP> hug <SEP> gr. <SEP> erasure <SEP> relative <SEP> cm3 <SEP> polymer <SEP> solid
<tb> (2) <SEP> C <SEP> in <SEP> kg / cm2 <SEP> (4) <SEP> of <SEP> grs / gr <SEP> of <SEP> ca- <SEP>
<tb> (3) <SEP> solid <SEP> analyzer
<tb>
 
 EMI15.2
 ----- --....------------------------------------- .. ... ---- ...---------
 EMI15.3
 
<tb>
<tb> 19 <SEP> 1.0 <SEP> 0.1 <SEP> 230 <SEP> 63/7 <SEP> 100X <SEP> 8.51
<tb> 20 <SEP> 1.0 <SEP> 0.1 <SEP> 230 <SEP> 63/8 <SEP> 50X <SEP> 4.10
<tb> 21 <SEP> 1.0 <SEP> 0.1 <SEP> 100-199 <SEP> 27-56 <SEP> 50D <SEP> 0.08
<tb> 0.7-5.3
<tb> 22 <SEP> 3.0 <SEP> 1.0 <SEP> 256 <SEP> 64.7 <SEP> 100X <SEP> 2.41
<tb> 23 <SEP> 0.5 <SEP> 0.2Li <SEP> 253 <SEP> 61 <SEP> 100X <SEP> 29.8
<tb> 24 <SEP> 1.0 <SEP> 0,

  1K <SEP> 254 <SEP> 58 <SEP> 100X <SEP> 1.96
<tb> 25 <SEP> 0.1 <SEP> 0.32 <SEP> 230 <SEP> 42 <SEP> 50B <SEP> 30.0
<tb> 26 <SEP> 0.1 <SEP> 0.64 <SEP> 230 <SEP> 42 <SEP> 50B <SEP> 21
<tb> 27 <SEP> 5.0 <SEP> 0.6 <SEP> 200 <SEP> 42 <SEP> 30D <SEP> 0.62
<tb> 28 <SEP> 2.0 <SEP> 0.5 <SEP> 150-203 <SEP> 72 <SEP> 50D <SEP> 1.45
<tb> (W)
<tb> 29 <SEP> 2.0 <SEP> 0.5 <SEP> 148 <SEP> 31/35 <SEP> 30D <SEP> 0.34
<tb> (W)
<tb> 30 <SEP> 5.0 <SEP> 0.5 <SEP> 233 <SEP> 67 <SEP> 50X <SEP> 0.26
<tb> (Cr)
<tb>
 

 <Desc / Clms Page number 16>

   TABLE (continued)
 EMI16.1
 Example 7 visco-Viscosi- Pelli- 10 "'y density
 EMI16.2
 
<tb>
<tb> specific <SEP> site <SEP> ty <SEP> to <SEP> mo- <SEP> cule <SEP> of the <SEP> polymer <SEP> Remarks
<tb> fique <SEP> ment <SEP> of <SEP> or <SEP> solid
<tb> (5) <SEP> the <SEP> fusion <SEP> movie
<tb> in <SEP> poises <SEP> (7)
<tb> (6)

  
<tb> 1 <SEP> Ins. <SEP> 67 <SEP> TF <SEP> 9756-9858
<tb> 2 <SEP> 41.9-58.8 <SEP> TF <SEP> 9650-9900 <SEP> Initial <SEP> quantity <SEP> of
<tb> solvento <SEP> Several
<tb> batches. <SEP> Quantity
<tb> total <SEP> of <SEP> solvent
<tb> 2500 <SEP> cm3
<tb> 3 <SEP> 64.6 <SEP> TF <SEP> 9673
<tb> 4 <SEP> TF <SEP> 9615-9776
<tb> 5 <SEP> 44.7-68.5 <SEP> TF <SEP> 9441-9597
<tb> 6 <SEP> 69 <SEP> TF <SEP> 9570
<tb> 7 <SEP> Ins.

   <SEP> 1,2 <SEP> 8 <SEP> TF <SEP> 9475
<tb> 8 <SEP> 19.3 <SEP> 2.45 <SEP> S1.TF <SEP> 9671
<tb> 9 <SEP> 25.3 <SEP> 3.76 <SEP> TF <SEP> 9676
<tb> 10 <SEP> 4.1 <SEP> B
<tb> 11 <SEP> 8.6 <SEP> 2.94 <SEP> B <SEP> 9686
<tb> 12 <SEP> 38 <SEP> 7.96 <SEP> TF <SEP> 9515
<tb> 13 <SEP> 13.5 <SEP> 1.335 <SEP> B <SEP> 9695
<tb> 14 <SEP> 23.7 <SEP> 1.496 <SEP> TF <SEP> 9634
<tb> 15 <SEP> 27.5 <SEP> 1.556 <SEP> TF <SEP> 9643
<tb> 16 <SEP> 63 <SEP> 2.95 <SEP> TF <SEP> 9538 <SEP> Alumina <SEP> and <SEP> molybdenum
<tb> reduced <SEP> to <SEP> 50% <SEP> by <SEP> H2-
<tb> 17 <SEP> 50 <SEP> 1,057 <SEP> TF <SEP> 9557 <SEP> Addition <SEP> of <SEP> 5 <SEP> cm3 <SEP> of
<tb>
 
 EMI16.3
 2-ethyl-1-herene
 EMI16.4
 
<tb>
<tb> 18 <SEP> 62.4 <SEP> 1,237 <SEP> TF <SEP> 9547 <SEP> Addition <SEP> of <SEP> 5 <SEP> cm3 <SEP> of
<tb> 2-methyl -? - butene
<tb>
 
 EMI16.5
 19 29.8 3,

  9 TF 9581 Catalyst g CoMo04
 EMI16.6
 
<tb>
<tb> 20 <SEP> 62.3 <SEP> 7.27 <SEP> TF <SEP> 9598 <SEP> Reduction <SEP> of catalyst <SEP>
<tb> 21 <SEP> to <SEP> 7000C <SEP> by <SEP> H2; <SEP> load <SEP>: <SEP> propylene;
<tb> Catalyst <SEP> COMo04
<tb> 22 <SEP> 22 <SEP> 6.85 <SEP> TF <SEP> 9670 <SEP> Bomb <SEP> heated <SEP> at <SEP> the
<tb> 23 <SEP> 12.6 <SEP> 6.54 <SEP> S1.T <SEP> 9651 <SEP> tempo <SEP> of <SEP> reaction.
<tb>
 
 EMI16.7
 



  24 16, z ¯ / 1 TF 9789 454 kg H2 for 1 h.
 EMI16.8
 
<tb>
<tb> 25 <SEP> 3.26
<tb> 26 <SEP> 3.26
<tb>
 

 <Desc / Clms Page number 17>

 TABLE (Continued)
 EMI17.1
 
<tb>
<tb> Eyemple <SEP> 102y <SEP> visco- <SEP> Viscosi- <SEP> Pelli- <SEP> 104 <SEP> y <SEP> density
<tb> specific <SEP> site <SEP> ty <SEP> to <SEP> mo- <SEP> cule <SEP> of the <SEP> polymer <SEP> Remarks
<tb> fique <SEP> ment <SEP> of <SEP> or <SEP> solid
<tb> (5) <SEP> the <SEP> fusion <SEP> movie
<tb> in <SEP> poises <SEP> (7)
<tb> (6)
<tb>
 
 EMI17.2
 -----------------------------------------------.-- ----
 EMI17.3
 
<tb>
<tb> 27 <SEP> 41, <SEP> 6 <SEP> 6.66 <SEP> TF <SEP> 9440 <SEP> Addition <SEP> of <SEP> 30 <SEP> cm3
<tb> of <SEP> 2- <SEP> butene
<tb> 28 <SEP> 113.0 <SEP> 1.8 <SEP> TF <SEP> 9377 <SEP> Addition <SEP> of <SEP> 20 <SEP> cm3
<tb> of <SEP> 2-butene
<tb> 29 <SEP> 113,

  6 <SEP> 9381 <SEP> Addition <SEP> of <SEP> propylene.
<tb>
 
 EMI17.4
 



  CH2 / CH3 22.



  OH2 / cli = 221,
 EMI17.5
 
<tb>
<tb> 30 <SEP> 1.35 <SEP> Reduced <SEP> catalyst
<tb> in <SEP> H2 <SEP> to <SEP> 375 C.
<tb>
 
 EMI17.6
 



  (1) Cr represents a chromium oyide-altsmin catalyst containing 31% by weight of chromium oxide; W represents a tungstic anhydride catalyst having the composition by weight of WO 3-8C% ZrO2.



   (2) Metallic sodium unless otherwise indicated.



   (3) When a pressure is simply given, this is the initial partial pressure of ethylene. When two pressures are given, the number on the right represents the initial partial pressure of the hydrogen.
 EMI17.7
 



  (4) Y represents xylenes, B benzenes, D decalin, T tetralin.
 EMI17.8
 (5) The specific acosity is (relative viscosity -1) and the relative viscosity is the ratio of the duration of flow out of the screw-
 EMI17.9
 cosimeter of a solution of 0.125 gr of polymer in 100 am3 of yylenes G.F. at 11000. and the flow time of 100 cm3 of -alenes C.P. at 110IC. (6) As determined by the method of Diennes and Klemm, J.Appl.
 EMI17.10
 Phys. 17, 458-71 (1946). The higher index refers to the assumption of 10 times the given number.



   (7) TF stands for tough and flexible. B means fragile.



   Sl means slightly.



   Although the results of the various examples are generally easy to understand, a brief interpretation of the various examples and some comparisons will be given below.



    The higher polyethylene yields shown in some examples have been and can be reproduced at will. Other examples indicating lower yields have nevertheless been introduced to illustrate particular aspects of the invention, although it appears that in such cases the usual adjustments required are generally not required.
 EMI17.11
 were carried out to obtain the highest possible polymer yields. From an industrial point of view, the processes described above can easily be carried out to produce at least 50 parts by weight of solid polyethylene per part by weight of metal oxide catalyst.

 <Desc / Clms Page number 18>

 



   In Example 4, it can be noted that the use of carefully purified xylene, even with the extremely high ratio of 1000 cm3 per gram of catalyst, resulted in a very high yield of polymer which could take the form of a hard and flexible film. The product was fractionated to provide a polymer having a melt viscosity of 5.6 x 107 poises and a specific viscosity x 105 equal to 98,600, and a second polymer having a melt viscosity of 4.0. x 108 poises.



   It is possible to compare with Example 4, Examples 1 and 2 in which the solvent / catalyst ratios were respectively 300 and 2500 cm3 / gr.



   Various solvents were used to carry out the polymerizations, the results of which are shown in the Tables. Thus, xylene was used in many examples, such as Examples 4 and 5. Benzene was used, for example in Examples 12, 13 , 25 and 26; decalin was used in a series of examples (8, 9 and 10) at increasing temperatures and in other examples (21, 27, 28 and 29) o Tetralin was used as the liquid reaction medium in example 15.



   The sodium / catalyst weight ratio has been varied in a number of successful examples: 0.05 in Example 14, 0.33 in Example 22, 0.1 in many examples (such as Examples 15 and 19), 0.5 in Example 2 and 1.0 in Examples 1, 4, 5 as well as in other examples. Good yields of solid polymer (30 grams and 21 grams respectively per gram of metal oxide catalyst) were obtained in Examples 25 and 26 in which the Na / metal oxide ratio was 3.2 and 6.4.



   In Example 17, 5 cc of 2-ethylhexene was used and it can be noted that the polymer was characterized by specific and, at the time of melting, high viscosities and by producing a hard and flexible film. Similar results were obtained in Example 18 in which 5 cm3 of 2-methyl-butene was added during the operation.



   The copolymerization of ethylene with propylene is illustrated in event 29 in which the catalyst consisted of 20% by weight of tungstic anhydride on zirconia, reduced by hydrogen at 450 Co The polymer was soft and rubbery and did not even melt at 300 ° C. The same catalyst was used in Example 28 to produce a hard flexible polymer from ethylene and 2-butene. In Example 27, the results were obtained from the copolymerization of ethylene with 2-butene in decalin in the presence of an 8% molybdic anhydride filter cake on alumina, which was pre-reduced with hydrogen to 480 Co at atmospheric pressure.



   An example of the polymerization of propylene is given in Example 21 in which a cobalt molybdate catalyst was used.



  It can be noted, by examining the yield of solid polymer, that propylene polymerizes with a much slower rate than ethylene in the process according to the invention.



   In Example 16, a molybdic anhydride catalyst pre-reduced to 50% by weight on an alumina-gamma support was used for the polymerization of ethylene and in Example 19, it was likewise successfully employed a cobalt molybdate catalyst. Tungstic anhydride catalysts were used in Examples 28 and 29 and chromium oxide in Example 30.



   Metallic lithium was shown to be an active promoter of ethylene polymerization in Example 23. Potassium was also shown to be a satisfactory promoter (Example 24) when used.

 <Desc / Clms Page number 19>

 reads in a small proportion relative to the whole molybdiqqe-alumina anhydride.



   While most of the examples were carried out at a temperature in the region of 230 ° C., much lower temperatures were studied, as can be seen on examination of Examples 7 and 21 and also higher temperatures. , as can be seen by examining Examples 13 and 10. In general, raising the reaction temperature while maintaining the other reaction variables at a constant value tends to reduce the specific viscosity of the solid polymer somewhat (compare Examples 9, 8 and 10), whereas lowering the reaction temperature from the optimum value in a given case reduces the rate of polymerization.



   In Example 20, a relatively high temperature was used to reduce the molybdic anhydride-alumina catalyst (700 ° C.).



   The addition of hydrogen to the reactor has been cited in numerous examples.



   Example 2 consisted of an operation in several batches rather than a single batch operation, the catalyst was kept inside the reactor, while a solution of the product was drawn off from time to time in the lenes. and that it was replaced by a solution of ethylene in xylenes. Before the end of the implementation of the process of this example, approximately 2500 cm 3 of solvent was contacted with the same catalyst charge.



   EXAMPLE 31.



   The process according to the invention has also been carried out successfully in a continuous operation, using a one liter autoclave comprising a stirrer of the type shown in the accompanying drawing. In the continuous operation, one passes a 9% by weight solution of ethylene in benzene through a retention reactor containing calcium hydride at 199 ° C. and from there to the autoclave (with a stirrer) containing 35 grams of a compound consisting of 8% by weight of pre-reduced molybdic anhydride and gamma-alumina and 16 gr. sodium.



  The reaction temperature was 243 ° C., the relative pressure 112 kg / cm2, the sodium / catalyst weight ratio 0.46 and the operating period was 15 hours. The conversion of ethylene to solid polymer was 10.9 g. per gram of catalyst. The following products are finally obtained: 380 g of solid ethylene polymer, 7.7 g of an ethylene polymer having the appearance of a grease and 4.2 g of benzene alkylation products, representing a convension of 97.9% by weight of ethylene in solid polymer. The percent conversion, based on the ethylene used, was 36.2. The solid polyethylene had a viscosity at the time of melting of 2.28 x 106 poises.



   Oxide catalysts of a Group 5a metal may be used in place of the oxides of a Group 6a metal in the process, i.e., oxides of vanadium, columbium and tantalum, the process remaining otherwise unchanged in all respects. essential aspects.



   The polymers produced by the process of the present invention can be subjected to such further processing as may be deemed desirable to suit the particular applications or to impart desired properties. Thus, the polymers can be extruded, mechanically ground, transformed into films, cast or converted into a sponge or network.



  Antioxidants, stabilizers, fillers, diluents, plasticizers, pigments, insecticides, fungicides, etc. etc. Polyethylenes can be used as

 <Desc / Clms Page number 20>

 coating, as binders, etc. on an even larger scale than the polyethylenes obtained by the prior processes.



   Polymers produced by the process of the present invention, particularly polymers having high specific viscosities, can be blended with lower molecular weight polyethylenes to give them stiffness or flexibility, or other desired properties. Likewise, the solid resin products obtained by the process of the present invention can be mixed in any desired proportions with hydrocarbon oils, waxes, such as paraffin or petrolatum, with ester waxes, with polybutylenes of high molecular weight and other organics.

   Small proportions of between about 0.01 and about 1% by weight of the various ethylene polymers obtained by the process of the present invention can be dissolved or dispersed in hydrocarbon lubricating oils to increase their viscosity index and to decrease oil consumption when compounded oils are used in engines; larger quantities of polyethylene can be mixed with oils of various kinds and for various reasons.



   The products having a molecular weight of 500,000 or more obtained by the present invention can be used in small proportions to substantially increase the viscosity of fluid liquid hydrocarbon oils and as gel forming agents for such oils.



  Dissolving approximately 1 g of ethylene polymer obtained by the present invention, having a specific viscosity x 105 close to 500,000, in approximately one liter of yylenes at a temperature close to the boiling point gives rise to an extremely viscous solution. .



   The polymers obtained by the present process can be subjected to chemical modification treatments, such as halogenation, halogenation followed by dehalogenation, sulfohalogenation, for example by treatment with sulfuryl chloride, sulfonation and other reactions to which the hydrocarbons can be subjected.



   CLAIMS
1. Process for preparing a normally solid hydrocarbon product, in which a normally gaseous olefin, selected from the class consisting of ethylene, propylene and mixtures containing ethylene and propylene, is contacted with an alkali metal and an oxide of a metal of Group 6a of the Mendeleef Periodic Table at a reaction temperature of from about 75 Co to about 325 Co and the normally solid hydrocarbon product thus produced is separated.


    

Claims (1)

2. The method of claim 1, wherein the oxide is partially pre-reduced before use. A process according to claims 1 or 2, wherein a smaller amount of hydrogen is introduced relative to the amount of olefin before substantial polymerization of that olefin has taken place, in order to rapidly and substantially initiate the reaction. polymerization of said olefin 4. A process according to claims 1, 2 or 3, wherein the reaction takes place in the presence of a liquid hydrocarbon reaction medium. 5. The method of claim 4, wherein the liquid hydrocarbon reaction medium is a saturated hydrocarbon. 6. The method of claim 4, wherein the liquid hydrocarbon reaction medium is a monocyclic aromatic hydrocarbon. <Desc / Clms Page number 21> 7. A process according to any preceding claim, wherein the oxide is that of a metal selected from the group consisting of chromium, molybdenum and tungsten. 8. A process for the production of a normally solid resinous hydrocarbon product, wherein ethylene is contacted in a concentration of from about 2% by weight to about 10% by weight in a liquid hydrocarbon reaction medium with. an alkali metal and an oxide of a metal of group 6a of the Mendeleef periodic table at a reaction temperature of between about 230 C and about 275 Co and at a relative reaction pressure of at least about 14 kg / cm2 , and the normally solid resinous hydrocarbon product thus obtained is separated. 9. A process for the production of a normally solid resinous hydrocarbon product, wherein ethylene is contacted in a concentration of from about 2% by weight to about 10% by weight in a liquid hydrocarbon reaction medium with. an alkali metal and a catalyst comprising a small proportion of an oxide of a metal selected from the group consisting of chromium, molybdenum and tungsten supported on a higher proportion of a metal oxide which is difficult to reduce at a reaction temperature of between about 230 Co and about 275 Co and under a relative reaction pressure of between about 14 and about 70 kg / cm 2, and the normally solid resinous hydrocarbon product thus obtained is separated. 10.Process according to claims 8 or 9, wherein the alkali metal consists of sodium, the liquid reaction medium consists of an aromatic hydrocarbon, the metal wave is a pre-reduced molybdenum oxide and the ratio sodium / molybdenum oxide is from about 0.001 to about 10. 11. The method of claims 8 or 9, wherein the alkali metal is sodium, the liquid reaction medium is benzene and the metal oxide consists of pre-reduced molybdenum oxide disposed on a support of. alumina-gamma. 12. The method of claims 8 or 9, wherein the alkali metal is lithium, the liquid reaction medium is benzene and the metal oxide is a pre-reduced molybdenum oxide disposed on an alumina-gamma support. 13. The process of claims 8 or 9, wherein the catalyst comprises a large proportion of a hardly reducible metal oxide and a lower proportion of a partially pre-reduced molybdenum oxide having an average valence of between about 2 and about. 5.50 14. The method of claim 13, wherein the liquid hydrocarbon reaction medium consists of benzene, the molybdenum oxide is disposed on an alumina-gamma support and the sodium / molybdenum catalyst ratio is between approximately 0.001 and about 10 by weight. 15.A process for the preparation of a resinous copolymer from ethylene and propylene, in which ethylene and propylene are simultaneously contacted with a liquid hydrocarbon reaction medium, an alkali metal and a catalyst comprising a strong proportion of a hardly reducible metal oxide and a small proportion of a partially reduced trioxide of a metal of group 6a of the Mendeleef periodic table at a reaction temperature of between about 75 and about 325 Co and the polymerization product is separated off normally solid thus obtained <Desc / Clms Page number 22> 16. The method of claim 15, wherein the oxide of the Group 6a metal is molybdic anhydride. 17. Process for the preparation of a hard resinous hydrocarbon product, from ethylene and propylene, characterized in that ethylene and propylene are simultaneously brought into contact with decalin and sodium. , a partially pre-reduced molybdenum trioxide, disposed on an alumina support, and having an average valence state of between about 2 and about 5.5, the weight ratio of sodium to -molybdenum trioyide disposed on a support being between about 0.001 and about 10 at a reaction temperature of between about 75 Co and about 325 ° C. and separating the hard resinous hydrocarbon product thus obtained. 180 A preparation process in which ethylene is contacted with an alkali metal and a catalyst comprising essentially an oxide of a metal from group 6a of the Mendeleef periodic table, at a reaction temperature of between about 75 C and about 325 C. and separated as the final product, solid polyethylenes having a specific gravity of between about 0.95 and 0.99 and a specific viscosity of between about 0.13 and about 1.1 when determined on a solution. of 1.25 g of these solid polyethylenes in 100 cm3 of -xylenes at 110 C. 19. The method of claim 18, wherein the contacting is carried out in the presence of a liquid hydrocarbon reaction medium. In appendix 1 drawing