Title of Invention	A CATALYST COMPOSITION FOR CONVERTING ETHYLENE TO LIGHT ALPHA OLEFINGS
Abstract	ABSTRACT 1071/MAS/97 The present invention relates to a catalyst for oligomerizing ethylene into light a-olefins. A zirconium compound is mixed with an acetal or ketal and a chlorine or bromine containing aluminium compound at a temperature ranging from 0 to 80"C in an atmosphere of ethylene or inert gas.

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This Invention relates to a catalyst composition I The products obtained with the above catalytic formulations are mainly constituted by alpha olefins having a chain length between C10 and C18. These ■Ixtures are suitable for uses hitherto allocated to oll§oners, plastlclzers and detergents. The expert known that most of these catalysts lead to the formation, In addition to the desired alpha olefins, of varying quantities of high molecular weight polymers, which considerably interfere with working. The present invention has found that the catalysts obtained by mixing a zirconium compound with at least one organic compound chosen from within the class of acetals of aldehydes and ketals of ketones and with at least one particular aluminium compound, which have an unexpected selectivity for the formation of lower ol igomers, mainly l-butene, 1—hexene, 1-octene and I-decene, which are used as comonomers with ethylene in the production of the linear low density polyethylene or as a starting base for synthetic lubricating oils. Apart from the improvement of the selectivity for light alpha olefins, the catalysts described in the present invention also aim at reducing the byproduct polymer to a very smaI I amount. The zirconium compounds used in the invention comply with the general formula ZrXx Yy Ox , in wh i ch X is a chlorine or bromine atom and Y is a radical chosen from among RO- a I koxy, RzN-amido or RCOO- carboxylate groups, R being a hydrocarbyl and preferably alkyl radical having 1 to 30 carbon atoms, whi 1st x and y can assume integral values of 0 to 4 and z is equal to 0 or 0.5, the sum x+y+2z being equal to 4. In exemplified manner reference can be made to zirconium ha I ides such as zirconium tetrachloride ZrCl4, zirconium-tetrabromide ZrBr4, alkoxides such as zirconium tetra-propylate Zr(0C3H7)4. zirconiurn• tetrabutyI ate Zr The organic compounds chosen from among the class of acetals and ketals used in the invention result from the condensation of an aldehyde or a ketone with a monoaIcohoI or a polyaicohol , e.g. a glycol . They comply with the following general formula: R2'^ ^0-R2 in which Rt • and R2 • are constituted by a hydrogen atom or a hydrocarbyl radical having I to 30 carbon atoms and Ri and R2 are hydrocarbyl radicals having 1 to 30 carbon atoms. The two radicals Ri* and R2 ' and the two radicals Ri and R2 can be the same or different and can also form part of a cycle. The foilow ing examples are given: diethoxy methane, di isopropoxy methane, diethoxy-1,l-ethane, di isobutoxy-l,)-ethane, dimethoxy- 1,1-decane, 2-nony1 - 1 ,3-di0x0 I an, dimethoxy-2,2- propane, dibutoxy-2,2-propane, dioctoxy-2,2-propane, dimethoxy-2,2-octane dimethoxy-1 , 1-eye Iohexane and di(ethy1-2-hexyloxy)-2,2-propane. The aluminium compounds used in the invention are represented by the general formula AIR"nX3-n, in R" is a hydrocarbyl radical, preferably a I kyI , which has I to 6 carbon atoms, X is a chlorine or bromine ^tom and preferably a chlorine atom and n is a number between 1 and 2 and can also in particular be I, 1,5 or 2. In exemplified manner reference is made to chloro-diethyl aluminium, dieh I oroethy I aluminium, ethyl aluminium sesquichI oride or mixtures thereof. The catalyst components can be contacted in a random order within a hydrocarbon, e.g. a saturated hydrocarbon such as hexane or heptane and/or an aromatic hydrocarbon such as toluene and/or one or more oIigomerization byproducts such as higher oligomers. Preferably, the zirconium compound is firstly mixed with acetal or ketal and then the aluminium compound is added thereto. The molar ratio between the acetal or ketal and the zirconium compound is approximately 0.1:1 to 5:1 and is preferably approximately 0.5:1 to 2:1. The molar ratio between the aluminium compound and the z i rcon i um compound is approx i mate Iy 1:1 to 100: 1 . preferably approximately 5:1 to 50:1. The zirconium concentration in the thus prepared catalytic solution is advantageously between I0-* and 0.5 mole per litre and preferably between 2»10-3 and 0.1 mole per litre. The temperature at which the three components are mixed is normally between -10 and +150°C, preferably between 0 and +80"C and e.g. equal to ambient temperature (15 to 300C). Mixing can take place under ethylene or an inert gas atmosphere. The thus obtained catalytic solution can be used as it is or can be diluted by adding products of the react i on. In an embodiment of the discontinuous performance of the oIigomerization catalytic reaction, a chosen volume of the catalytic solution prepared in the manner described hereinbefore is introduced into a reactor equipped with conventional stirring and cooling systems, followed by pressurization with ethylene to a pressure generally between 0.5 and 15 MPa and prefer¬ably between 1 and 10 MPa. The temperature is gener¬ally maintained at between 20 and 180 °C, preferably between 40 and ISO^C. The ol igomerization reactor is supplied with ethylene at constant pressure until the total liquid volume produced represents between 2 and 50 times the volume of the initially introduced catalytic solution. The catalyst is then destroyed, e.g. by adding water, followed by the removal and separation of the products of the reaction and any solvent. In the case of continuous operation, the procedure is preferably as follows. The cataIytic so Iution is injected at the same time as the ethylene into a ■reactor stirred with conventional mechanical means or by an external recirculation. It is also possible to separately inject the components of the catalyst into the reaction medium, e.g. the interaction product of the zirconium compound with the acetal (or ketal) on the one hand and the hydrocarby I-a I urninium ha I ide on the other. The temperature is maintained at between 20 and I800C, preferably between 40 and 1 500C and the pressure is generally adjusted between 0.5 and 15 MPa. By means of an expansion valve, which keeps the pressure constant, there is an outflow of part of the reaction mixture at a mass flow equal to that of the fluids introduced. The thus expanded fluid is fed into a distillation column system making it possible to separate the oligomers from the ethyl«n« on the one hand, whereby said ethylene can be returned to the reactor, and then the individual ol igomers on the other. The heavy products containing the catalyst can be i nc i nerated. Accordingly, tlie present invention provides a catalyst composition for the conversion of ethylene into liglit alpha olefins, comprising (i) a zinconium compound of the formula ZrXxYyO^, in wliich X is a chlorine or bromine atom, Y is a radial selected from the group consisting of RO-, (R)2N- and RCOO- groups, in which R is a hydrocarbyl radical havmg 1 to 30 carbon atoms, x and y are 0 or an integer of 1 to 4, and z is 0 or 0.5, the sum x+y+2z being equal to 4, (ii) an organic acetal or ketal compound of fomiula R-i' 0—-R "^^^Z 0 R C/5 m I in which Ri' and R2' are independently a hydrogen atom or a hydrocarbyl radical having 1 to 30 carbon atoms and Ri and R2 aie independently hydrocarbyl radicals having 1 to 30 carbon atoms, and (iii) an aluminium compound of the formula AIR",^3.j, in which R" is a hydrocarbyl radical having 1 to 6 carbon atoms, X is a clilorine or bromine atom and n is a number of JQom 1 to 2, such tliat tlie molar ratio of the acetal or ketal compound to the zinconium compound is approximately 0.1:1 to 5.: 1 and tlie molai- ratio of the aluminium compound to tlie zirconium compound is approximately 1:1 to 100:1, wherein said zirconium compound, said organic acetal or ketal and said aluminium compound are mixed at 0°C to 80°C under ethylene or inert gas atmosphere. llie following examples illustrate the invention witliout limiting its scope. j,«i3 EXAMPLE 1 Into a stainless steel autoclave having a useful volume of 250 ml and equipped v^ith a double envelope making it possible to regulate the temperature by circulation of water, is introduced in successive manner and under an argon atmosphere and at ambient temperature: 0.2 x 10-3 mole of the complex C The temperature is then raised to 750C, whi 1st introducing ethylene into the autoclave so as to main¬tain a constant pressure of 6 MPa. After reacting for 2 hours, ethylene introduction is stopped and the catalyst destroyed by injecting 2 ml of water under pressure. in alI, 71 g of ethylene have been consumed. The composition of the products is given in Table I. In addition, 0.2 X by weight of solid polymer, based on the ethylene consumed, is collected. EXAMPLE 2 (COMPARATIVE) Using the same equipment as that in example 1 and under the same conditions, except that the dimethoxy-2,2-propane was omitted, there was a consumption of 96.5 g of ethylene after 15 minutes of reaction. The composition of the products obtained, given in Table 1, shows the beneficial effect of the presence of the ketal in the catalyst on the light alpha olefin selectivity. in addition, collection took place of 8.4X of sol id polymer, based on the ethylene consumed, i.e. much more than in example 1. EXAMPLE 3 Into a 100 ml spherical glass flask placed under an inert atmosphere was transferred so as to be pro¬tected from humidity 2 x 10-3 mole of sublimated zir¬conium tetrachloride, fol lowed by the injection by means of a hypodermic syringe of 45 ml of dried, de-aerated toluene. The white suspension was stirred at ambient temperature by means of a bar magnet and to the flask was added 2 x 10-3 mole of dimethoxy-1 ,1-decane in solution in 5 ml of toluene. After a few minutes, the zirconium chloride dissolved and the colouring of the thus obtained homogeneous solution evolves from pale ye I low, to orange and then to deep red, indicating the formation of a complex. Into the same autoclave as that described in example I successive introduction takes place under an argon atmosphere and at ambient temperature of 5 ml of the complex solution prepared hereinbefore, i.e. 0.2 X 10-3 mole of zirconium, 50 ml of heptane and then 1.2 X 10-3 mole of ethyl aluminium sesquich1 oride A2Et3Cl3 in solution in 10 ml of heptane. The temperature was then raised to 95°C whi1st introducing ethylene into the autoclave, so as to main¬tain a constant pressure of 6 MPa. Following 2 hours reaction, ethylene introduction was stopped and the catalyst destroyed by the injection under pressure of 2 ml of water. In a I I , 51 g of ethylene were consumed. The composition of the products is given in Table I . On ly traces of solid polymer were collected and namely in quantities too smaI I to be accurately measured. EXAMPLE 4 Using the same equipment and the same operating procedure as described in example I, except that the dimethoxy-1,I-decane was replaced by di isopropoxy methane in the same proportions, the oli gomer i za t i on reaction consumed 98.3 g of ethylene in I hour. The composition of the products is given in Table 1. Only traces of solid polymer were col Iected. EXAMPLE 5 Using the same equipment and the same operating procedure as described in example 3, except that the dimethoxy-1,1-decane was replaced by dimethoxy-Z,2-propane in the same proportions, the ol igomerization reaction consumed 77.3 g of ethylene in I hour. The composition of the products is given in Table I. Only traces of solid polymer were collected. EXAMPLE 6 Using the same equipment and with the same operating procedure as described in example 3, except that dimethoxy—I,1-decane was replaced by dioctoxy-2,2-propane in the same proportions, the ol igomerization reaction consumed 88.5 g of ethylene in 1 hour. The composition of the products is given in Table 1, Only traces of solid polymer wer e collected. EXAMPLE 7 In the same equipment and with the same operating procedure as described in example 3, except that the dimethoxy-l,l-decane was replaced by a double molar quantity of dimethoxy-2,2-octane (i.e. 0.4 x 10-3 mole of ketaI for 0.2 x 10-3 mole of zirconium used), the oligomerization reaction consumed 39.3 g of ethylene in 3 hours. The composition of the products is given in Table I. Only traces of solid polymer were collected. EXAMPLE 8 Using the same equipment and the same operating procedure as described in example I, except that the dimethoxy-I,1-decane was replaced by dibutoxy-2,2-propane in the same proportions and that the oligo-merization reaction temperature was fixed at 650C instead of 950C, said reaction consumed 44 g of ethylene in 2 hours. The composition of the products is given in Table 1. Only traces of solid polymer were collected. EXAMPLE 9 Using the same equipment and with the same operating procedure as described in example 3, except that the dimethoxy-2,2-decane was replaced by dioctoxy-2,2-propane in the same proportions and that intro¬duction took place of 2.4 x 10-3 mole of chIorodiethy I-aluminium in place of 1.2 x 10-3 mole of ethyl aluminium sesquichI or ide, the oI igomerization reaction consumed 83.4 g of ethylene in 30 minutes. The composition of the products is given in Table I. Collection also took place of 0.47 % by weight of sol id polymer, based on the ethylene consumed. EXAMPLE 10 Using the same equipment and the same operating procedure as described in example 9, except that a double quantity of dioctoxy-2,2-propane was used (i.e. 0.4 x 10-3 mole of ketal for 0.2 x 10-3 mole of zir¬conium), the oli gomer ization reaction consumed 58.9 g of ethylene in 2 hours. The composition of the products is given in Table I. Collection also took place of 1.35 % by weight of solid polymer, based on the ethylene consumed. EXAMPLE 1 1 Using the same equipment and the same operating procedure as described in example 3, except that the d i me thoxy-2 , 2--decane was replaced by diisopropoxy methane in the same proportions and that 2.4 x 10-3 mole of chIorodiethy I aluminium was introduced in place of 1.2 X 10-3 mole of ethyl aluminium sesquichloride and that the oligomerization reaction was performed at 700C instead of 950C, said reaction consumed 69 g of ethylene in 1 hour. The composition of the products is given in Table 1. Collection also took place of 0.86 *A by weight of solid polymer, based on the ethylene consumed. EXAMPLE 12 (COMPARATIVE) Using the same equipment and the same operating procedure as described in example 3, except that di¬me thoxy- 1 , 1 -decane was not introduced (so that the zirconium tetrachloride was introduced in suspended state into the autoclave), the reaction consumed 32.8 g of ethylene in 4 hours. The composition of the products given in Table 1 shows a poor selectivity for light alpha olefins. A large amount of polymer, equal to 15 % by weight, based on the ethylene consumed, was col lected. This example iIlustrates the double improvement resulting from the introduction of an acetal with respect to the selectivity for light alp ha olefins and the reduction of the byproduct polymer level. This patent application is divided out of our cope.nding Indian Patent Application 448/MAS/93 which claims a process for the production of liyht alpha olefins by oligomerisation of ethylene using the catalyst composition claimed in this specification. This application has been divided out of Indian Patent AppHcation No. 448/MAS/93 (180021), which relates to a process for producing light alpha olefins from ethylene comprising oligomerising etliylene in the presence of a catalyst composition consisting of a mixture of zirconium compound of formula ZrX^Yy O^ in which X is a chlorine or bromine atom. Y is a radical chosen from witlun the group formed by RO- alkoxy, RiN-amido and RCOO- carboxylate groups, in which R is a hydrocarbyl radical having 1 to 30 carbon atoms, x and y has an integral values of 0 to 4 and z is equal to 0 or 0.5, tlie sum x+y+2z being equal to 4, (2) an organic compound of formula in which R1' and R2' are a hydrogen atom or a hydrocarbyl radical having 1 to 30 carbon atoms and R1 and R2 hydrocarbyl radicals having 1 to 30 carbon atoms and (3) an aluminium compound of fonnula .AJR"„Xj.„ in which R" is a hydrocarbyl radical g^ having 1 to 6 carbon atoms, X is a clilorine or bromine atom and n is a number ' 1^ between 1 and 2 and recovering the alpha olefins from tlie reaction product in a m known mamier. WE CLAIM: 1. A catalyst composition for tlie conversion of ethylene into light alplia olefins, comprising (i) a zinconium compound of tlie formula ZrXxYyO^, in wliich X is a chlorine or bromine atom, Y is a radial selected from the group consisting of RO-, (R)2N- and RCOO- groups, in which R is a hydrocarbyl radical having 1 to 30 carbon atoms, x and y are 0 or an integer of 1 to 4, and z is 0 or 0.5, tlie sum x+Y+2z being equal to 4, (ii) an organic acetal or ketai compound of formula in which R1' and R2' are independently a hydrogen atom or a hydrocarbyl radical having 1 to 30 carbon atoms and R1 and R2 are independently hydrocarbyl radicals having 1 to 30 carbon atoms, and (iii) an aluminium compound of the formula AlR"nX3.n m which R" is a hydrocarbyl radical having 1 to 6 carbon atoms, X is a chlorine or bromine atom and n is a number of from 1 to 2, such tliat tlie niolai" ratio of the acetal or ketal compound to tlie zinconium compound is approximately 0.1:1 to 5:1 and the molar ratio of the aluminium compound to the zirconium compound is approximately 1:1 to 100:1, wherein said zirconium compound, said organic acetal or ketal and said aluminium compound are mixed at 0°C to 80°C under ethylene or inert gas atmosphere. n ! and mixture thereof

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