PREPARATION OF POLIOXITETRAMETILENG ICOL The present invention relates to a process for the preparation of copolymers of tetrahydrofuran (THF) and but-2-in-l, 4-diol by the catalytic polymerization of THF. The present invention relates particularly to a process for the preparation of polyand I rame i lengl icol. Polyethylene glycol, also known as polyhydrofuran (PTHF), is produced on a worldwide scale and serves as an intermediate product for the preparation of polyurethane, polyester and polyamide elastomers for the preparation of which a component is used. dial The incorporation of PTHF into these polymers makes them soft and flexible, and PTHF is therefore known as the soft segmented component for these polymers. The cationic polymerization of tetrahydrofuran (THF) with the aid of catalysts was described by Meerwein et al. (Angew, Chem. 72 (19? &0; 0), 927). They are either used as catalysts, pre-formed catalysts, or the catalysts are produced in situ in the reaction mixture. This is achieved by producing ions or ions on the reaction medium with the help of strong acids, such as boron trifluoride, aluminum chloride, tin tetrachloride, antimony pentachloride, iron (III) chloride. either pentaf phosphorus luoride, or by means of Brünsted acids such as, for example, acid
perchloric acid, tetrafluorobolic acid, fluorosulfonic acid, chlorosulfonic acid, hei acid < chlorostat (IV), iodic acid, hexacloraantimonic acid (V) or tetrachloroferric acid (III), and with the aid of reactive compounds known as promoters, such as, for example, alkylene oxides, for example ethylene oxide, propylene oxide , epichlorohydrin, esters of ortho acids, acetals, alpha-halaethers, acetyl chloride, carboxylic anhydrides, thienyl chloride or phosphoryl chloride, said oxonium ions initiating the polymerization of THF. Among the large number of these catalyst systems, however, only a few have achieved industrial importance since some of them are highly corrosive and / or cause colorless PTHF products in the PTHF preparation which have only limited uses. Accordingly, many of these catalyst systems do not have the catalytic action in the true sense of the word but must be used in stoichiometric amounts, based on the macromolecule to be prepared, and consumed during polymerization. US-A-3 358 042 describes the preparation of PTHF using fluorosulfonic acid as a catalyst, a particular disadvantage of the use of halogen-containing catalyst compounds is that they cause the formation of halogenated byproducts during the preparation of PTHF,
said by-products are very difficult to separate from pure PTHF and have a negative effect on their properties. In the preparation of PTHF in the presence of the established promoters, these promoters are incorporated into the PTHF molecule such that the primary product of the polymerization of THF is not PTHF but a derivative of PTHF. For example, alkali oxides are incorporated. The copolymers are formed as comonomers in the polymer with the result that THF / alkylene oxide copolymers are formed which have properties, particularly performance characteristics, that differ from the properties of PTHF. The use of carbohydrate anhydrides as promoters results primarily in the formation of PTHF diesters, from which PTHF must be released in an additional reaction, for example, by hydrolysis or by transesterification (see US-A document). -2 499 725 and DE-A 27 60 272). In accordance with US-A-5 149 862, zirconium dioxide with sulfate impurities is used as a heterogeneous acidic polymerization catalyst which is insoluble in the reaction medium. In order to accelerate the polymerization, a mixture of acetic acid and acetic anhydride is added to the reaction medium since the polymerization is carried out only very slowly in the presence of these promoters and, for example,
a conversion of only 64 / is achieved. during a period of 19 hours. This process results in the formation of PTHF diacetates that have to be converted to THF by hydrolysis or by transesterification. JP-A 83 028/1983 discloses the polymerization of THF in the presence of an acyl halide or carboxylic anhydride, using either heterapal or co-catalyst. PTHF diesters which have to be hydrolyzed in PTHF are formed in the same way. PTHF diesters are also formed in the polymerization of THF chemically pretreated with bleach-earth catalysts in the presence of carbaxyl anhydrides, for example acetic anhydride, according to EP-A-0 003 112. A major disadvantage of this process Polymerization THF is related to the costs for the use of acetic anhydride and its elimination of the PTHF derivative (methyl ester) formed as the primary product. On the other hand, if polymerization of THF is carried out using water as telogen (substance terminating a chain), PTHF is formed directly. In accordance with US-A-4 120 903, PTHF can be prepared from THF and water with the aid of afian (P) superacid ion exchange resins. The disadvantage of this process is the high molecular weight of the resulting PTHF, which is about 10,000 daltons. Such high weight PTHF
molecular to date has no industrial relevance. US-A-4 568 775 and US-A-4 658 065 describe, respectively, a process for the preparation of PTHF and the copolymerization of THF with a polyol, heteropolysates being used as catalysts. The heteropoly acids are soluble to a certain extent in the polymerization mixture and in the polymer and, since they cause the discoloration of the PTHF product, they must be removed therefrom by expensive technical measures - addition of a hydrocarbon for the presentation of the heteropoly acid. , removal of the precipitated heterapolid and removal of the ag ree oil. In US-A-4 303 782, zeolites are used for the preparation of PTHF, however, the polymers of PTHF that can be obtained by means of this process have extremely high average molecular weights - in Mn = 250,000 to 500,000 Daltons - and could not be used for the aforementioned intended uses. Therefore, this process does not present industrial importance either. A further important disadvantage of this process is the low spatial performance (for example 4 * 1 of PTHF in 24 hours) that is achieved with the zeolites used there. All the aforementioned processes for the direct preparation of PTHF have, especially in the case of PTHF within the range of molecular weights of 500 to 3,500
daltons, which has an industrial interest, the disadvantage of low time-to-time yields in heterogeneous catalysis or the disadvantage of a costly removal of the catalyst in homogeneous catalysis. It is an object of the present invention to provide a process that makes it possible to obtain PTHF in high space-time yields, that is, with high selectivity in combination, with high conversion of THF, and with simple removal of the catalyst. We have found that this object is achieved, surprisingly by the polymerization of tetrahydrofuran in a strongly acidic heterogeneous catalyst in the presence of but-2-in-l, 4-diol and then by catalytic hydrogenation of the polymethyl tetramethyl glycols containing triple CC links to provide the polyoxitetra ethylene glycol. The course of the reaction can be written by the following equation, only one of the possible copolymers is indicated as a product of the reaction of THF with but-2-in-l, 4-diol
The present invention therefore relates to a process for the preparation of pal io? tetramethyl glycols or copolol of THF and but-2-in-l, 4-diol by
catalytic polymerization of THF, the polymerization being carried out in a heterogeneous acid catalyst having acid centers of an acidity pKa <; +2 in a concentration of at least 0.005 mmol / g catalyst in the presence of but-2-in-l, 4-diol. The present invention relates in particular to a process for the preparation of polyoxytetra and ethylene glycol, the copal polymers of THF and but-2-in-l, 4-diol or polylactic tefrac and the glycols, prepared in accordance with the present invention and which contain triple bonds, with a hydrogenation catalyst being carried in the presence of hydrogen at a temperature comprised between 20aC and 300 * C and under a pressure of 1 to 300 bars. In the sub-ranges indicating ions, preferred embodiments of the invention are defined. In accordance with the present invention, supported catalysts comprising an oxide carrier, contain oxygen-containing compounds of molybdenum or tungsten or mixtures of other compounds as catalytically active compounds and, if desired, can additionally receive sulphate or phosphate groups, they are preferably used as polymerization catalysts. For the conversion into its catalytically active form, the supported catalysts are subjected to calcination at a temperature comprised between 500 [deg.] C. and 1000 [deg.] C. after the precursors of the molybdenum compounds and / or
Oxygen-containing, catalytically active tungsten have been applied to the vehicle, the vehicle and the precursor compound with the use of catalysts that can be used in accordance with the present invention. Suitable oxide vehicles are, for example, zirconium dioxide, titanium dioxide, hafnium oxide, yttrium oxide, iron (III) oxide, alumina, tin oxide (IV), silica, zinc oxide and mixtures thereof. oxides. Zirconium dioxide and / or titanium dioxide are particularly preferred. The catalysts which can be used in accordance with the present invention generally contain from 0.1 to 50, preferably from 1 to 30, particularly from 5 to 20 * /, by weight of the catalytically active molybdenum or tungsten compounds containing oxygen. or of the mixtures of the catalytically active compounds of these oxygen-containing metals, based in each case on the total weight of the catalyst and, since the chemical structure of the catalytically active compounds containing oxygen, molybdenum and / or tungsten does not it is known precisely to date but can only be bleached, for example, from the data of the IR spectra of the catalysts which can be used according to the invention, is calculated in each case as Mo03 or W03.
In principle, in addition to containing the catalytically active molybdenum and / or tungsten containing oxygen compounds, the novel catalysts can also have impurities of 0.05 to 10, preferably 0.1 to 5, particularly 0.25 to 3% by weight in basis in each case to the total weight of the catalyst containing oxygen-containing sulfur and / or phosphorus-containing compounds. Since the chemical form in which these sulfur or phosphorus containing compounds are present in the prepared catalyst is also unknown, the contents of these groups in the catalyst are calculated together as S04 or P04. For the preparation of the novel catalysts, hydroxides of the relevant carrier components are used as starting materials as a general rule. When these hydroxides are commercially available, commercially available hydroxides or initial materials for the preparation of the oxide vehicles can be used, but preferably the oxide vehicles are prepared using freshly precipitated hydroxides which, after their precipitation, they are generally dried at a temperature of between 20 and 350 ° C, preferably of 50 to 150 ° C, particularly of 1000 to 120 ° C, under atmospheric or reduced pressure. In general, the water-soluble or hydrolysable salts of
the elements constituting the vehicle, for example its halides, preferably its substrates or carboxylates, particularly its acetates, are used as initial compounds for the preparation of these hydroxides. Suitable starting compounds for the precipitation of these hydroxides are, for example, zirconyl chloride, γ-irconyl nitrate, titanyl chloride, titanyl nitrate, yttrium nitrate, yttrium acetate, aluminum nitrate, aluminum acetate, iron nitrate. (III), tin halides (IV), and par- ticularly tin (IV) chloride, zinc nitrate or zinc acetate. The corresponding hydroxides are precipitated from the solutions of these salts, preferably by means of a solution of aqueous ammonia. Alternately, the hydrides can be obtained by the addition of dilute or weak acids, such as for example acetic acid, to water-soluble hydroxo complexes of the relevant metals up to the pre-ipitation of the relevant hydroxide. The hydroxides can also be obtained by hydrolysis of organometallic compounds, for example the alcoholates of the relevant metals such as, for example, zirconium tetraethylate, zirconia tetraisopropylate, titanium tetramethyl, titanium tetra isopropylate, etc. In general, a gelatinous precipitate forms during the precipitation of these hydroxides, said precipitate
provides an amorphous powder to the X-rays after drying. It is possible that these amorphous X-ray precipitates are composed not only of the hydroxides of the relevant metals but additionally of a large number of other hydroxide-containing compounds, for example hydrated oxides, hydroxo complexes and water-soluble, etc. However, since the exact chemical composition of these precipitates can not be determined, for the purposes of this application it will be considered for simplicity that they are the hydrogens of the established metals. For the purposes of this application, the term "hydroxides" is therefore generally used to qualify hydrated containing precipitates obtained in the aforementioned precipitation methods. When silica is used as the oxide carrier, the initial material used for the preparation of the catalysts which can be used in accordance with the present invention is preferably freshly precipitated silica, which can be obtained, by acidifying a water glass solution, and which is preferably dried before further processing, in accordance with what is described above for the hydroxide precipitates. The precursor compounds of the catalytically active, oxygen-containing molybdenum and / or tungsten compounds are applied to the hydrides of the carrier or vehicle components.
the silica, which are prepared in this way and also known as vehicle precursors in this application, the application being achieved preferably by impregnation with an aqueous solution of these precursor compounds. For example, the water-soluble salts of tungstic acid (H2W04), as formed, for example, by the dissolution of tungsten trioxide in aqueous ammonia, ie, onotungstates, and isopolystates formed therefrom with acidification, for example, paratungstates or metatungstates, and water-soluble salts of molybdic acid (H2Ma04), as formed, for example, by dissolving molybdenum trioxide in aqueous ammonia and isopol imol ibdates formed from there, upon acidification, particularly the metadata ibdates and ibulates, can be used as water-soluble precursor compounds of the catalytically active, oxygen-containing tungsten or malbdenium compounds. Preferably, the ammonium salts of these tunstico and molybdic acids are applied as precursor compounds to the hydroxides of the carrier or to the silica components by impregnation. As regards the nomenclature, preparation composition of the moldata, isbpol imol ibdates, tungstates and isotungstates, reference is made to Ro pps Chemie-Le? Ikon, 8th edition, volume 4, pages 2659-2660, Francksche Verlagsbuchhandlung, Stuttgart, 1985; Rb pps Chemie-Lexikon,
8th edition, volume 6, pages 4641-4644, Stuttgart 1988, and Co prehensive Inorganic Chemistry, edition, Volume 3, pages 738-741 and 766-768, Perganon Press, New York, 1973. Instead of the precursor compounds of molybdenum and tungsten, respectively, it is also possible to employ molybdenum and tungsten heteropolides, with, for example, 12-tungstatosylic acid (H4 (Si (W12040)), 26H2D ) either 12-mol ibdatose 1 iic acid, or its water soluble salts, preferably its ammonium salts, to apply the molybdenum or tungsten to the hydroxide, i.e., a hydroxide-containing carrier precursor. The hydroxides of the particular carrier components employed having hydroxides used in this manner, and the impregnated silica are generally dried at a temperature between 80 and 350 ° C, preferably 90 to 150 ° C, under atmospheric pressure or reduced pressure. It is also possible to introduce the established precursor compounds of the catalytically active molybdenum or tungsten containing oxygen compounds into the subsequently obtained catalyst by a complete mixture with one or more of the indicated hydroxides. The calcination of the vehicle precursors, which have been treated in this way, to provide the catalysts that can be employed in accordance with the present invention is carried
performed in the same manner as for vehicle precursors impregnated with these precursor compounds. However, the impregnation method is preferably used for the preparation of the catalysts that can be used according to the present invention. The catalyst precursors impregnated and dried in this way are converted into finished catalysts by calcination in the air at a temperature comprised between 500 and 1000 * C- preferably between 550 to 900 ° C, especially between 600 and 800 ° C. In the course of the calcination, the hydroxides of the vehicle components and the silica becomes the oxide vehicle, and the precursor compounds of the catalytically active molybdenum or tungsten containing oxygen compounds, which have been applied on these impregnation vehicles are converted into catalytically active components. Calcination at these high temperatures is critical to achieve a high conversion and therefore a high space-time yield in the polymerization of THF. At lower calcining temperatures, the catalysts also produce THF polymerization, but only with low non-economic conversions. Based on the IR investigations of catalysts prepared in this way, Yinyan et al., Pare Metals 11 (1992), 185, assumes that, in the case of catalysts supported on
zirconium with tungsten impurities, the catalytically active, oxygen-containing tungsten compound precursor compound, said precursor compound has been applied onto the zirconium hydroxide by impregnation, forms a chemical bond with the hydroxide groups of the vehicle precursor in the high calcination temperatures employed, resulting in the formation of the catalytically active, oxygen-containing tungsten compound, which differs substantially in its chemical structure and in its chemical activity, particularly in terms of its catalytic properties, from the compounds of tungsten containing oxygen only adsorbed on the vehicle of zirconium dioxide. This situation is also considered for molybdenum-containing supported catalysts which can be used according to the invention. As previously stated, supported catalysts which, apart from molybdenum and / or tungsten, are further contaminated with sulfur and / or phosphorus-containing compounds can be used advantageously in the novel process. These catalysts are prepared in a manner similar to that described above for catalysts containing only molybdenum and / or tungsten compounds, sulfur and / or phosphorus-containing compounds being applied only by impregnation on the hydroxides of the
vehicle components, prepared in a similar way, or on silica. The sulfur and / or phosphorus compounds can be applied to the vehicle simultaneously with the application of the molybdenum and / or tungsten component, or afterwards. The sulfur and / or phosphorus compounds are preferably prepared by impregnation of the hydroxides of the carrier components or the silica with an aqueous solution of a compound containing the sulphate or phosphate groups, for example sulfuric acid or phosphoric acid. . Solutions of water-soluble sulphates or phosphates can also be used for impregnation purposes, particularly ammonium sulphates or ammonium phosphates. A further method for the application of the phosphorus-containing precursor compounds together with the precursor compounds containing molybdenum or tungsten on the hydroxide carrier precursor is the treatment of the hydroxide carrier precursors with heteropoxy acids containing phosphorus by the methods described above. Examples of such heteropolides are 12-tungstatofosphoric acid (H3PW12Q40.H20) and 12-mai ibdatofosfórico acid (H3PMol2040.xH20). Heteropol, molybdenum or tungsten with organic acids of phosphorus, for example phosphonic oxides, can also be used for this purpose. Heteropolysacids can also be used
for this purpose in the form of its salts, preferably ammonium salts. During the calcination under the above-mentioned conditions, the heteropolotides are decomposed into the catalytically active molybdenum or tungsten containing oxygen compounds. Some of the catalysts that can be used according to the present invention are known and their preparation is described, for example, in JP-A 288 339/1989, JP-A 293 375/1993, J. Chem. Soc., Chem. Co mun. (1987), 1259, and Rare Metals 11 (1992), 185. The catalysts have been used to date only in petrochemical processes, for example as catalysts for alkylations, ions and for the catalytic thermocracking of chains. hydrocarbon, that is, processes not related to the novel process. In addition to the aforementioned zirconium dioxides containing tungsten and molybdenum, zirconium dioxides contaminated with sulphate can be used as polymerization catalysts. The properties and the preparation of zirconium dioxides doped with sulfate are described, for example, in M. Hiño and K. Arata, J. Chem. Soc., Chem. Camm. (1980), 851. Bleaching earths can also be used as
polymerization catalysts in the novel process. In mineralogical terms, the whitening lands or lands of Fuller belong to the class of montmori lonitas. These are hydrated aluminum hydrates that occur naturally and in which some of the aluminum ions may have been replaced by iron, magnesium or other alkali metals or alkaline earth metals. The ratio between silica and oxides of divalent or trivalent metals in these minerals is generally 4: 1. Commercial products, which have been generally activated by acid treatment and have a water content of 4 to 8 * by weight, based on total weight, are used in large quantities to refine edible oils, fats and mineral oils and with adsorbents and fillers. The bleaching soils which can be obtained under the trade name Tonsil (mr) of types K 10 KSF-0, KO and KS from Süd-Che ie AG, Munich, are used in a particularly preferred manner in the novel process. It is also possible to employ zeolites as polymerization catalysts in the novel process. Zeolites are defined as a class of aluminum silicates that, due to their particular chemical structure, form three-dimensional networks that have pores and channels defined in the crystal. According to its composition, in particular the relationship
molar SY02-A1203, and its crystalline structure which is determined not only by the established atomic ratio but also by the separation method of the zeolites, a distinction is made between several types of zeolites, some of their names being attributable to minerals of zeolites that occur naturally in composition and similar structure, for example faujasites, mordenites and clones, or that receive acronyms when there are no specific analogs in nature for the zeolites synthesized or when these zeolites form a structural subclass of the zeolites occurring in nature, for example zealites Y and X belonging to the type of faujasite or zeolites having a pentasyl structure, such as for example ZSM-5, ZSM-11 or ZBM-10. Summaries of the chemical composition of zeolites, their three-dimensional and chemical structure and their method of preparation appear, for example, in DWBreck, Zeolite Molecular Sieves, iley, New York, 1974. Zeolites suitable for the novel process have a molar ratio YES02 / A1203 from 4: 1 to 100: 1, preferably from 6c 1 to 90: 1, particularly from 10: 1 to 80: 1. The primary crystals of these zeolites have a particle size of up to 0.5 μm, preferably up to 0.1 μm, particularly up to 0.05 μm. The zeolites that can be used as catalysts of
Polymerization in the novel process is employed in the H form. In this form, acidic OH groups are present in the zeolite. If the zeolites are not obtained in the form H in their preparation, they can easily be converted to the catalytically active form H, for example by treatment with, for example, mineral acids, such as for example hydrochloric acid, sulfuric acid or phosphoric acid, or or by thermal treatment of suitable precursor zeolites containing, for example, ammonium ions, for example by heating at a temperature comprised between 450 and 600 ° C, preferably between 500 and 550 ° C. All zeolites that meet the aforementioned requirements can be used as polymerization catalysts in the novel process. Examples of these zeolites are zeolites from the group of mordenites and zeolites from the group of faujasites, particularly the X and Y zeolites synthesized. Aluminophosphates or silicoaluminophosphates having a zeolite structure can also be used. Zeolites having a pentasyl structure, such as for example ZSM-5, ZSM-11 and ZBM-10, are especially preferred. Among these zeolites of the pentacyl group, the zeolites which in turn have particularly advantageous properties are the zeolites which were prepared in such a way that they are substantially free of organic compounds.
alkali metals, ie, that their alkali metal content is generally below 50 ppm by weight. The preparation of non-alkaline ZBM-10 zeolites is described in EP-A-0 007 081, and a method for the preparation of substantially non-alkaline ZSM-5 zeolites is described by Müller et al. in Occelli, Robson (Eds.)., Zeolite Synthesis, A.C.S. Sy p. Series 398 (1989), 346. The zeolites prepared by these methods are present in the H form after a heat treatment, for example, at a temperature comprised between 500 and 600 ° C. In addition to the zeolites, polymers containing groups of alpha-fluarosulfonic acid can also be used as polymerization catalysts Perfluorinated copolymers containing alpha-fluorosulfonic acid groups and are available, for example under the name afian (mr) of EI du Pont de Nemours and Company are preferred. which can be used in accordance with the invention can be used in the novel process in powder form, for example when the process is carried out by means of the subscription process, or with advantage as molds, for example in the form of cylinders, spheres, rings, spirals or flakes, particularly in fixed bed arrangement of the catalyst, said arrangement is preferred when, for example, they are used loop reactors
or when the process is carried out by continuous methods. In principle, any desired THF can be used as a monomer. Commercial THF or THF purified by acid treatment (see EP-A-0 003 112) or by distillation are preferably used. According to the invention, but-2-in-l, 4-diol is used as telogen, that is, as a substance which achieves the chain termination in the polymerization reaction. The polymer is preferably fed to the polymerization in the form of a solution in THF. Since telogen stops polimerization, the average molecular weight of the unsaturated PTHF copolymer can be controlled by the amount of telogen used. The greater the amount of telogen contained in the reaction mixture, the lower the average molecular weight of the unsaturated PTHF polymer. Depending on the telogen content of the polymerization mixture, the relevant PTHF copolymers having average molecular weights of 250 to 10,000 can be prepared in a controlled manner. The novel process is preferably used to prepare relevant PTHF copolymers having average molecular weights of 500 to 5000, preferably from 650 to 3500, daltons. For this purpose, the telogen is added in amounts of 0.04 to 17, preferably 0.2 to 8, and particularly 0.4 to%.
molar, based on the amount of THF used. The polymerization is generally carried out at a temperature between 0 and 100 ° C, preferably 25 ° C up to the boiling point of THF. The pressure used in general terms is not a critical factor for the result of the polymerization and the process is therefore carried out generally at atmospheric pressure or under the autogenous pressure of the polymerization system. In order to avoid the formation of ether peroxides, the polymerization is preferably carried out under an inert gas atmosphere. The inert gases which may be used are, for example, nitrogen, hydrogen, carbon dioxide or noble gases, preferably nitrogen. The polymerization step of the novel process can be carried out batchwise or continuously, generally preferring the continuous process for economic reasons. In the batch process, reactive THF and but-2-in-l, 4-diol and the catalyst generally react in a loop reactor or stirred vessel at set temperatures until the desired conversion of THF is achieved. The reaction time may be from 0.5 to 40, preferably from 1 to 30 hours, depending on the aggregate amount of catalyst. For the polymerization ion, the catalysts are added in
General in an amount of 1 to 90, preferably 4 to 70, and particularly 8 to 60% by weight, based on the weight of the THF employed. For the preparation, in the case of the batch process, the mixture of the discharged reaction is separated from the catalyst suspended therein, preferably by filtration, decantation or centrifugation. The discharged polymerization mixture released from the catalyst is usually prepared by distillation, diethyl THF being preferably distilled in a first step. In a second purification step, one can, if desired, separate the low molecular weight PTHF from the polymer by distillation under reduced pressure and said PTHF can be recycled to the reaction. Automatically, volatile THF oligomers can be depolarized, for example, by the process of DE-A 30 42 960, and can be recycled to the reaction in this way. In a preferred embodiment of the invention, the conversion of the copolymers containing triple C-C bonds and comprising THF and but-2-in-l, 4-diol into PTHF is carried out by means of catalytic hydrogenation. When the hydrogenation is carried out, the layers containing triple C-C bonds and the hydrogen react in a hydrogenation catalyst in general under a pressure of from 1 to 300, preferably from 20 to 250, and particularly from
40 to 200 bar and at a temperature comprised between 20 and 300 [deg.] C., preferably 60 to 200 [deg.] C., particularly 100 to 160 [deg.] C., to provide polyoxy tetramethylglycol. The hydrogenation can be carried out without solvent or, preferably, in the presence of an inert solvent under the conditions of the reaction. Such solvents can be, for example, ethers, such as, for example, tetrahydrofuran, methyl tert-butyl methyl ether, di-n-butyl ether, alcohols, such as methanol, ethanol, propanol, oroprapanol, butanol, isobutanol. or tert-butanol, hydrocarbons, such as for example n-hexane, n-heptane or n-octane, and N-alquillactams, such as, for example, N-met i iprol idona or N-actilpirral idona. A preferred solvent is tetrahydrofuran. The reacted polymerization mixtures obtained after separation of the polymerization catalyst are particularly preferably hydrogenated. In general, all catalysts suitable for the hydrogenation of triple C-C bonds can be used as hydrogenation catalysts in the novel process. The catalysts The hydrogenation catalysts which are dissolved in the reaction stage to provide a haemogeneous solution, as described, for example in Hauben-Weyl, Methoden der Organischen Cheie, Volume IV / lc, pages 16 to 26, can be used
However, heterogeneous hydrostatic catalysts, that is to say, hydrogenation catalysts essentially insoluble in the reaction medium, are preferably used in the novel process. In principle, virtually all heterogeneous hydrogenation catalysts can be used for the hydrogenation of the triple C-C bonds of the copolymers on single C-C bonds. Among these hydrogenation catalysts, those containing one or more elements of group Ib, VI Ib and VI Ib of the Periodic Table of the Elements, particularly nickel, copper and / or palladium, are preferred. In addition to these components, and, if required, a vehicle, these catalysts may contain one or more other elements such as, for example, chromium, tungsten, molybdenum, manganese and / or rhenium. According to the preparation, the catalysts can also contain oxidized phosphorous compounds, such as for example phosphate. Heterogeneous hydrogenation catalysts consisting of metals in finely divided, activated form having a large surface area, such as for example Raney nickel, Raney copper or palladium sponge can be used in the novel process. For example, precipitated catalysts can also be used in the novel process. Such catalysts can be prepared by
pre-testing their catalytically active components from their salt solutions, particularly from the solutions of their nitrates and / or acetates, for example by adding hydroxide of alkali metals and / or alkali metal hydroxides and / or carbonate solutions such as, for example, slightly soluble hydroxides, hydrated oxides, basic salts or carbonates, then drying the obtained precipitates and then converting them by calcination in general at a temperature comprised between 300 and 700 ° C, particularly from 400 to 700 ° C. 600ßC, in the relevant oxides, mixed oxides and / or mixed valence oxides, reduced by treatment with hydrogen or with a gas containing hydrogen to, in general terms, a temperature between 100 and 700 ° C, particularly in 150 and 400ßC, in metals and / or
, relevant oxide compounds of low oxidation state and become the truly catalytically active form.
As a general rule, the reduction continues until no more water is formed. In the preparation of precipitated catalysts containing a vehicle, the precipitation of the catalytically active components can be carried out in the presence of the relevant vehicle. However, the alitically active components can also be precipitated with the simulataneous benefit of the vehicle from the
relevant salt solutions. In addition, conventionally prepared supported catalysts containing one or more of the aforementioned catalytically active elements can also be used as heterogeneous hydrogenation catalysts in the novel process. Such supported catalysts are advantageously prepared by impregnating the vehicle with a metal salt solution of the relevant elements, followed by drying and calcination in general at a temperature between 300 and 700 ° C, preferably between 400 and 600 ° C. , and by reducing a stream of hydrogen-containing gas. The impregnated carrier is generally dried at a temperature between 20 and 200 ° C, preferably at a temperature between 50 and 150 ° C, under atmospheric pressure or reduced pressure. Higher drying temperatures can also be used. The reduction of the catalytically active catalyst components is generally carried out under the conditions stated above for the precipitated catalysts. In general, the oxides of alkaline earth metals, aluminum and titanium, zirconium dioxide, silica, kieselguhr, silica gel, aluminas, silicates, such as for example magnesium silicate or aluminum silicate, barium sulfate or carbon activated can be used as vehicles.
The preferred vehicles are zirconium dioxide, alumina, silica and activated carbon. Of course, it is also possible to use mixtures of different vehicles with the vehicle for catalysts which can be used in the novel process. Hydrogenation catalysts which are preferably used in the novel process are Raney nickel, Raney copper, palladium sponge, impregnated supported catalysts such as palladium on activated carbon, palladium on alumina, palladium on silica, palladium on calcium oxide, palladium in barium sulfate, nickel in alumina, nickel in silica, nickel in zirconium dioxide, nickel in titanium dioxide, nickel in activated carbon, copper in alumina, copper in silica, copper in zirconium dioxide, copper in dioxide titanium, copper in activated carbon or nickel and copper in silica, and precipitated catalysts containing vehicle, such as Ni / Cu in zirconium dioxide, Ni / Cu in alumina or Ni / Cu in titanium dioxide. Raney nickel, the aforementioned palladium supported catalysts, particularly palladium in alumina or palladium in a vehicle comprising alumina and calcium oxide, and nickel and copper in precipitated catalysts containing a carrier, particularly nickel and copper catalysts in Zirconium dioxide is particularly preferably used in the hydrogenation process
fifty
novel for the preparation of polytetrahydrofuran. The palladium supported catalysts generally contain from 0.2 to 10, preferably from 0.5 to 5 * 4 by weight, calculated as Pd and based on the total weight of the catalyst, of palladium. The alumina / calcium oxide carrier for the palladium supported catalysts can generally contain up to 50, preferably up to 30 * / * by weight, based on the weight of the vehicle, of calcium oxide. Additional preferred supported catalysts are nickel and copper in silica catalysts having a nickel content in general from 5 to 40, preferably from 10 to 30% by weight, calculated as NiO, a copper content in general from 1 to 15, preferably from 5 to 10 * / by weight, calculated as CuO and an SiO2 content in general from 10 to 90, preferably from 30 to 80% by weight based in each case on the total weight of the non-reduced oxide catalyst. These catalysts may additionally contain from 0.1 to 5 * 4 by weight, calculated as Mn304, from manganese and from 0.1 to 5 '/ by weight, calculated as H3P04, of phosphorus, based on each case on the total weight of the catalyst. rust not reduced. Obviously, the aforementioned contents of catalyst components add up to a total content of 100% by weight of these companers in the catalyst. These catalysts are advantageously prepared by impregnating the silica mold with salt solutions of
the active catalytic components, for example, with solutions of their nitrates, acetates or sulfates, and then drying the impregnated vehicles at a temperature between 20 and 200 [deg.] C., preferably 100 to 150 [deg.] C., under atmospheric pressure or reduced pressure, calcining them at a temperature comprised between 400 and 600 * C, preferably from 500 to 600 * C, and reducing them with gases containing hydrogen. Such catalysts are presented, for example, in EP-A-295 435. The precipitated catalysts which comprise nickel and copper in zirconium dioxide can generally contain from 20 to 70, preferably from 40 to 60% by weight, calculated as NiO, nickel, in general from 5 to 40, preferably from 10 to 35% by weight, calculated as CuO, from copper and in general from 25 to 45% by weight of zirconium dioxide, based on each case in the total weight of the non-reduced oxide catalyst. Furthermore, these catalysts may contain from 0.1 to 5% by weight, calculated as Mo03 and based on the total weight of the non-reduced oxide catalyst, molybdenum. Such catalysts and their preparation are presented in US-A-5 037 793 which is incorporated herein by reference. The precipitated catalysts as well as the supported catalysts can also be activated in situ in the reaction mixture by the hydrogenate present there. In a preferred embodiment of the invention, however, the
catalysts are reduced with hydrogen at a temperature comprised between 20 and 300 ° C, preferably 80 to 250 ° C, before being used. The hydrogenation step of the novel process can be carried out either continuously or in batches. In the continuous process it is possible to use, for example, tube reactors in which the catalyst is advantageously arranged in the form of a bed on which the reaction mixture can pass through the liquid phase method or the method of runoff bed. In the batch process, either simple stirred reactors or, advantageously, loop reactors can be used. When loop reactors are used, the catalyst is preferably arranged in the form of a fixed bed. Hydrogenating in the novel process is preferably carried out in the liquid phase. The hydrogenation product, poly and tetrahydrofuran (PTHF), is generally isolated from the hydrogenation mixture discharged in a conventional manner, for example, by distilling off the solvent contained in said hydrogenation mixture and any other low molecular weight compound present. The novel process provides polytetrahydrofuran having a very low color number in high time yields and with simple catalyst removal. At the same time, the
Polytetrahydrofuran prepared in accordance with the present invention has a molecular weight of 500 to 3500, a range that is interesting from an industrial perspective. In a further embodiment of the present invention, the triple CC bonds of THF and but-2-1,4-diol copolymers are converted to CC double bonds by partial hydrogenation, resulting in a polymer corresponding to a Copal was THF / but-2-in-l, 4-dial in its chemical structure. Such copolymers THF / but-2-in-l, 4-diol are used, for example, as diol components for the preparation of radiation curable polyurethane and polyester finishes. The catalysts proposed above for the hydrogenation of the CC triple bonds in CC single bonds can be used for the hydrogenation of the triple CC bonds in CC double bonds, but in general it must be ensured that the amount of hydrogen used for the partial hydrogenation does not exceed the stoichiometric amount of hydrogen required for the partial hydrogenation of the triple CC bonds in CC double bonds. The partial hydrogenation of the C-C triple bonds in C-C double bonds is preferably carried out using poisoned partial hydrogenation catalysts, for example palladium lindlar which can be prepared by impregnating a vehicle, for example, carbonate.
calcium, with a water soluble palladium compound, for example Pd (N03) 2, by reducing the palladium compound applied with, for example, hydrogen to provide a palladium metal and by subsequent partial poisoning of the palladium supported catalyst resulting with a lead compound, for example lead acetate (II). Such Lindlar catalysts are commercially available. Other preferred partially poisoned palladium catalysts are the catalysts described in German Patent Application No. P 43 33 293.5 and which can be prepared by first successive gas-phase deposition of the palladium and after the lead and / or cadmium on a wire cloth of metal woven or a metal sheet. The partial hydrogenation of the triple CC bonds of the tetrahydrofuran / but-2-in-1, 4-dial cappolymers in CC double bonds is generally carried out at a temperature comprised between 0 and 100 ° C, preferably from 0 to 50 ° C, in particular from 10 to 30 ° C, and at a pressure of 1 to 50, preferably 1 to 5 and in particular 2 to 3 bar Hydrogen is preferably used in the stoichiometric amount required for the partial hydrogenation of the CC triple bonds. If the hydrogenation of all triple CC bonds in double bonds is not contemplated, hydrogen can also be introduced in an amount
less than the stoichiometric amount. The hydrogenation can be carried out either in batches, for example in stirred vessels using suspended catalysts, or in a continuous manner, for example in tube reactors with a fixed bed catalyst. The following examples illustrate the invention and constitute preferred embodiments of the invention. Preparation of catalysts Catalyst A: Bleaching earths K 10 powder (montmorillonite treated with Süd-Chemie acid) which was further calcined for 2 hours at a temperature of 350 * C was used as catalyst A. Catalyst B: A soil of K10 powder whitening from Süd-Chemie was used in the same way as starting material for catalyst B and was molded to provide 2.5 mm e-products and then calcined at a temperature of 350 * 0. Catalyst C: Catalyst C was prepared by the addition of 2600 g of zirconium hydroxide to 2260 g of a 26.5% by weight Mo03 solution in 12% ammonia. This solution was kneaded for 30 minutes and then dried for 16 hours at a temperature of 120 * C. The dried material was kneaded with 40
56
g of 75% phosphoric acid and 1.4 1 of water for 30 minutes. Subsequently, the drying was carried out for 2 hours at a temperature of 120 ° C. The powder formed after sieving was formed into pellets and the resulting pellets were then calcined at a temperature of 600 ° C for 2 hours. The catalyst had a molybdenum content of 20% by weight, calculated as molybdenum dioxide, and a phosphorus content of 1% by weight, calculated as P04, based on the total weight of the catalyst. Catalyst D: Catalyst D was prepared by the addition of 26O0 g of zirconium hydroxide to a solution of 640 g of tungstic acid (H2 04) in 3470 g of a 25% ammonia solution. This mixture was kneaded for 30 minutes and then dried for 2 hours at a temperature of 120 ° C. The powder formed after sieving was formed into pellets and the resulting pellets (3 x 3 m) were then calcined at 625 ° C. The catalyst had a tungsten content of 20% by weight, calculated as tungsten trioxide and based on the total catalyst weight Catalyst E: Catalyst E was prepared by adding 1600 g of zirconium hydroxide to a solution of 425 g of tungstic acid and 200 g of ammonium sulfate in 3470 g of a 25% ammonia solution. This mixture was kneaded during
minutes and then dried for 2 hours at a temperature of 120 ° C. The powder formed after sieving was formed into pellets and the resulting pellets were then calcined at a temperature of 850 ° C for 2 hours. The catalyst had a tungsten content of 18% by weight, calculated as tungsten trioxide, and a sulfur content of 7% by weight, calculated with S04, based on the total weight of the catalyst. Catalyst F: Catalyst F was prepared by a method of preparation due to M. Hiño and K. Arata, J. Chem. Soc., Chem. Camm. (1980), 851, zirconium hydroxide precipitating from an aqueous zircanyl nitrate solution by the addition of ammonia. The precipitated zirconium hydroxide was dried at a temperature of 100 ° C, kneaded with IN sulfuric acid and then molded to provide 3 x 3 mm pellets. The pellets were dried at 100 ° C and calcined at 550 ° C for 2 hours. The catalyst had a sulfur content of 6% by weight, calculated as S04 and based on the total weight of the catalyst. Determination of the acidity of the catalysts The acidity of the catalysts A to F was determined in accordance with that described by K. Tanabe in Catalysis: Science and Technology (ed., JR Anderson and M. Bondart), Spri nger-Verlag, Berlin, 1981, Vol. 2, chapter 5,
.8
pages 235 et seq., by titration of n-butylamine against Hammet indicator 2-amino-5-azotoluene (pKa = +2.0). The catalysts were dried beforehand at a temperature of 200'C and under a pressure of 0.01 mbar. The solvent used was benzene. For the determination of its acidity, the particulate catalyst was suspended in benzene and titrated with n-butylamine in the presence of the indicator. The indicator is yellow in its basic form and changes color to red (acid form) as soon as it is adsorbed on the surface of the catalyst. The title of n-buti sheet that refers to restore the yellow color of the indicator is a measurement of the concentration of the acid acid centers pKa <; +2 in the catalyst, expressed in mmol / g of catalyst or my equivalent (mval) / g of catalyst, and consequently of its acidity. Determination of molecular weights The average molecular weights (Mn) of the copolymers of THF / butindiol and PTHF were determined by analysis of terminal groups by 1 H-NMR spectroscopy. Mn is defined by the equation in which "ci" is the concentration of the individual polymer species in the polymer mixture obtained and where Mi is the molecular weight of the individual polymer species. Mn = ECi / Eí Mi)
The copolymers of THF / bu indiol obtained by polymerization of THF in the presence of but-2-in-l, 4-dioi show the following signals in the spectrum of 1 H-NMR (the chemical shift data refer to the maximum of the signal; solvent: CDC13): signal at: 4.3 ppm; b: 4.2 ppm; c: 3.6 ppm; d: 3.5 ppm; e: 3.4 ppm; ft 1.6 ppm. As shown in formula I, these signals can be assigned to the indicated protons. The areas of signals a, c and e were used to determine molecular weight. HO-CHVCHf2-CHf2-CHe2-O -...- 0-CHe2-CHf2 Mf2-CHd2-0-CHb2-C-C-CHYOH (I)
EXAMPLES Polymerization of THF in batch in the presence of but-2-in-l, 4-diol Example 1 In this example, catalyst A having an acidity (pKa < +2) of 0.17 mmol acid centers / g was used in this example. of catalyst 10 g of catalyst A in powder form which had been dried beforehand for 20 hours at a temperature of
180 aC and a pressure of 0.3 mbar to remove the adsorbed water were added to 20 g of peroxide-free THF containing 1.6 wt% of but-2-in-l, 4-dio and 30 wppm of water under an atmosphere of gaß of argon in a 100 ml glass flask with a reflux condenser. The
suspension was stirred for 20 hours at a temperature of 50 * C. After this time, the cooled reaction mixture was filtered and the catalyst powder was washed with three times 20 g of THF. The filtrates were combined and evaporated at a temperature of 70 ° C / 20 mbar in a rotary operator and then treated for 1 hour in a bulb tube at 150 ° C / 0.3 mbar. 3.8 g of a colorless copolymer of THF / butyndiol was obtained in the form of a distillation residue (yield: 19%, based on the THF used). The polymer had an average molecular weight Mn of 1850. Examples 2 to 6 Examples 2 to 6 were carried out in accordance with that described in example 1, the various catalysts B to F being used. The average molecular weights Mn resulting from the THF / butenediol copolymers, the yields achieved and the acidities of the catalysts used that were determined by means of Hammet titration, appear in the list in Table 1. TABLE 1
Ex. Catalyst Type of Acidity (pKa yield Mn catalyst <+2) (mmol / g of (1H-NMR) of copolymer catalyst (%) 2 B ground white- 0.07 15.9 2500
queadora 3 C Mo03-Zr02-P04 0.10 14.2 720
4 D W03 ~ Zr02 0.12 13.2 1700
^ E W03-Zr02-S042- 0.12 18.0 1200 6 F ZrP2 ~ S042- 0.13 16.8 950
Polymerization of THF in batches in the presence of butan-1,4-diol Comparison example 1 (comparison with example 4) In accordance with that described in example 1, 20 g of THF containing 0.15% by weight of butan-1,4-diol and 30 ppm of water at a temperature of 50 ° C for 20 hours with 10 g of catalyst D in the form of 3 × 3 mm pellets which had been dried from the forehead for 20 hours at a temperature of 180 C and at a pressure of 0.3 mbar After the removal of the catalyst and evaporation of the filtrate under reduced pressure according to that described in example 1, a polymeric evaporation residue was obtained in a yield of only 4.1%, based on the THF used The molecular weight of PTHF was 1700. Continuous polymerization of THF in the presence of but-2-in-l, 4-diol Example 7 A 250 ml fixed bed reactor was filled under an atmosphere of argon, with 352 g (250 ml) of catalyst F
Zr02 / S04 dried for 24 hours at a temperature of 180 ° C and under a pressure of 0.3 mbar. The polymerization apparatus was filled with THF containing but-2-in-l, 4-diol (1.5% by weight of but-2-in-i, 4-dial). This reaction mixture was first pumped into the catalyst for 24 hours at a reactor temperature of 50 ° C. Then, THF containing additional but-2-yl, 4-dial (1.5 wt.% But-2-in-l, 4-diol) was fed continuously at a catalyst space velocity of 0.04 kg. THF per 1 catalyst per hour. The ion / feed ion ratio was about 40 and the reactor temperature was 50 ° C. The discharged polymerization mixture (730 g) obtained during an operating time of 72 hours was prepared. After the distillation of unconverted THF and after the residue obtained had been subjected to molecular distillation at a temperature of 150 ° C / 0.3 mbar, the resulting distillation residue comprised 80 g of a copolymer of THF / butindiol which, according to the 1 H-NMR spectrum, had an average molecular weight Mn of 970 Daltones. The average yield over time of the 72-hour reaction was 11%. A space-time yield of 4.4 g of THF / butyndiol 970 copolymer per 1 catalyst per hour was obtained. Capol continuous monitoring of THF in the presence of butan-1,4-diol
Comparison Example 2 (comparison with Example 7): A 250 ml fixed bed reactor was filled, under an argon atmosphere, with 372 g (220 ml) of the dried catalyst MoQ3-Zr02 for 24 hours at a temperature of 180 * C / 0.3 mbar. The polymerization apparatus was filled with THF containing butan-1,4-diol (0.4% by weight of butan-1,4-diol). This reaction mixture was pumped first into the catalyst for 24 hours at a reactor temperature of 50 ° C. Then, THF containing additional butan-1,4-diol (0.4% butan-1, 4-dial enp) was fed continuously at a catalyst space velocity of 0.04 kg THF per liter of catalyst per hour. The reacted polymerization mixture (725 g) obtained during a 72 hour experiment time was prepared according to that described in example 7, by distilling off the non-converted THF and carrying out a molecular distillation. 49 g of PTHF were obtained which, according to the 1 H-NMR spectrum, had an average molecular weight M n of 980 daltons. The yield was 6.8%. A spatial yield of only 2.5 g of PTHF 980 per 1 catalyst per hour was obtained. Continuous polymerization of THF in the presence of but-2-in-l, 4-diol E p plo 8 A fixed bed reactor of 250 ml was filled, under
Argon atmosphere, with 333 g (250 ml) of the W03-Zr02 catalyst dried for 24 hours at a temperature of 180 ° C / 0.3 mbar. The polymerization apparatus was filled with THF containing but-2-1,4-diol (0.9% by weight of but-2-1,4-diol). This reaction mixture was pumped first into the catalyst for 24 hours at a reactor temperature of 50 ° C. Then, THF containing additional but-2-in-l, 4-dial (0.9 wt.% But-2-in-l, 4-diol) was fed continuously at a catalyst space velocity of 0.32 kg. THF per liter of catalyst per hour. The circulation / feed ratio was about 10 and the reactor temperature was 50 ° C. The discharged polymerization mixture (1.9 kg) obtained during a 24 hour experiment time was prepared according to that described in example 7, by distilling off the non-converted THF and carrying out a molecular distillation. 185 g of a THF / butyndiol copolymer were obtained which, according to the 1 H-NMR spectrum, had an average molecular weight M n of 2500 daltons. The yield was 10%. A space-time yield of 32 g of THF / butindiol 2500 capitol was obtained per liter of catalyst per hour. Example 9 The continuous polymerization of THF described in the plo axis 8 and carried out in the catalyst D continued under the conditions of
otherwise identical reaction with a feed containing 2.0 wt% of but-2-ynyl, 4-diol in THF, at a catalyst space velocity of 0.16 kg of THF per 1 of catalyst per hour. After the stabilization of the THF conversion, the mixture of the discharged reaction (2.9 kg) obtained during a 72-hour experiment time was collected. After preparation and molecular distillation according to that described in example 7, 210 g of THF / bu indiol copolymer was isolated, said copolymer had an average molecular weight Mn of 1180 in accordance with • -spectrum 1H-NMR. The yield was 7% based on the THF used. A space-time yield of 11 g of THF / butyndiol 1180 copolymer per liter of catalyst per hour was obtained. EXAMPLE 10 The continuous polymerization of THF described in Example 9 and carried out in catalyst D was continued under otherwise identical reaction conditions with a feed containing 1.5% by weight of butne-2-in-l, 4-dial in THF, at a catalyst space velocity of 0.16 kg THF per liter of catalyst per hour. After the stabilization of the THF conversion, the mixture of the discharged reaction (2.0 kg) obtained during an experiment time of 72 hours was collected. After preparation and molecular distillation in accordance with that described in
Example 7, 280 g of THF / butyndiol copolymer was isolated, said copal had an average molecular weight Mn of 1620 in accordance with the 1 H-NMR spectrum. The yield was 10% based on the THF used. A space-time yield of 16 g of THF / butyndiol 1620 copolymer per liter of catalyst per hour was obtained. As shown in the previous examples, the novel process leads to a substantially higher space-time performance, in combination with higher THF conversions than a conventional process in which butan-1,4-diol is used as telogen instead of butan-2-1,4-diol. EXAMPLES OF HYDROBENATION Hydrogenation in batches of THF / butyndiol copolymers in PTHF Example 11 In a 50 ml metal autoclave, 5 g of a THF / butyndiol copolymer prepared according to Example 1, in 10 g of tetrahydrofuran, were hydrogenated with hydrogen using 2 g of Rapey nickel at a temperature of 100 ° C and under a pressure of 40 bar for 6 hours. After removal of the catalyst and distillation of the solvent under reduced pressure, 4.8 g of residue was obtained. This residue was further subjected to distillation in a bulb tube at a temperature of
150ßC / 0.3 mbar. The obtained distillation residue was a colorless polytetrahydrofuran which, according to the 1H-NMR spectrum, did not contain any triple C-C bond. The PTHF obtained in this way had an average molecular weight Mn of 1900. EXAMPLE 12 10 g of a THF / butyndiol copolymer prepared in a similar manner to Example 6 and dissolved in 10 g of tetrahydrofuran were hydrogenated with hydrogen using 4 g of a supported catalyst containing nickel and copper (prepared in accordance with US-A-5 037 793, nickel content 50%, calculated as NiO, copper content 17%, calculated as CuO, molybdenum content 2%, calculated as Mo03; vehicle: Zr02 31% by weight, catalyst form: 6 x 3 mm pellets) at a temperature of 120 ° C and under a pressure of 40 bar for 6 hours. The catalyst had been activated in advance in a stream of hydrogen at a temperature of 200 ° C for 2 hours. The preparation and molecular distillation of the bicarbonate hydrogenation mixture was carried out in accordance with that described in Example 11. 9.2 g of colorless poly-tetrahydrofuran were obtained which, according to the 1 H-NMR spectrum, contained no triple bond CC and whose residual double bond content was < 0.5% The PTHF obtained in this way had an average molecular weight Mn of 1020.
EXAMPLE 13 In accordance with that described in Example 11, 10 g of a copolymer of THF / butindiol prepared in a manner similar to Example 2 and dissolved in 20 g of tetrahydrofuran were hydrogenated with hydrogen in 4 g of a supported catalyst of palladium in alumina containing calcium (prepared by impregnation of a vehicle of A1203 / Ca0, obtained by wet kneading of A1203 and CaO, drying at a temperature of 120 * C and calcination at 550 ° C, with a solution of aqueous palladium nitrate; palladium content : 0.6% by weight, calculated as Pd, calcium content: 20% by weight, calculated as CaO, 79.4% by weight of A1203); in the form of 4 mm extruded aterials at a temperature of 120 ° C and under a pressure of 40 bar for 8 hours. The preparation and distillation were carried out in accordance with that described in example 11. 9.1 g of colorless PTHF having an average molecular weight Mn of 2600 was obtained. According to the 1H-MR spectrum, the product did not contain any triple CC link and the residual content of the CC double bonds was < 3%. EXAMPLE 14 In accordance with that described in example 11, 5 g of a copolymer of THF / butindiol prepared in a manner similar to example 4, in 10 g of tetrahydrofuran, were hydrogenated with hydrogen using 2 g of a palladium catalyst in
alumina (prepared by impregnating extruded particles of A1203 with an aqueous palladium nitrate solution, drying at 120 ° C and calcination at 440 ° C; Palladium content: 0.5% by weight, calculated as Pd; 99.5% by weight of A1203) in the form of 4 mm extruded particles at a temperature of 140 ° C and under a pressure of 40 bar for 6 hours. The catalyst had been activated in advance in a hydrogen stream for 2 hours at a temperature of 150 ° C. The preparation and distillation in bulb tube of the hydrogenac mixture. The discharged ion was carried out in accordance with that described in Example 11. 4.5 g of colorless PTHF were obtained which, according to the 1 H-NMR spectrum, did not contain any CC triple bonds and had a residual double bond content lower than 2%. The molecular weight Mn was 1750.