ANIONIC POLYMERIZATION OF SILOXANES
20240124654 ยท 2024-04-18
Assignee
Inventors
- Andreas WENNG (Haar, DE)
- Alexander HOFER (Benediktbeuern, DE)
- Gunther Duschek (Benediktbeuern, DE)
- Dirk Sielemann (Wolfratshausen, DE)
Cpc classification
B01J35/50
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
The invention relates to a catalyst pellet for anionic polymerization of organosiloxanes and/or for equilibration of organopolysiloxanes, comprising at least one (earth) alkali metal oxide, its preparation, as well as a method for polymerization of organosiloxanes and/or for equilibration of organopolysiloxanes by means of the catalyst pellet.
Claims
1. A catalyst pellet for the anionic polymerization of organosiloxanes and/or for the equilibration of organopolysiloxanes comprising (i) at least one (earth) alkali metal oxide, in particular selected from sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide or barium oxide, and (ii) optionally at least one binding agent, in particular selected from phyllosilicate, such as bentonite, sodium silicate, sodium aluminate, aluminosilicate, silicic acid and its esters or at least one carrier material, in particular selected from aluminum oxide, zirconium oxide, silicon dioxide, titanium oxide, titanium dioxide, metal phosphate, such as hydroxyapatite, cerium oxide, carbon, and mixed oxides such as SiO.sub.2Al.sub.2O.sub.3, SiO.sub.2TiO.sub.2, ZrO.sub.2Al.sub.2O.sub.3 or mixtures of two or more of these materials, wherein the CO.sub.2 desorption enthalpy of the catalyst pellet is 25-350 kJ/mol, preferably 50-300 kJ/mol, measured by temperature programmed desorption of CO.sub.2.
2. The catalyst pellet according to claim 1, wherein the (earth) alkali metal oxide (i) has an mean pore radius of 2-130 nm, preferably 2-65 nm, measured according to DIN-66134, and/or has a specific pore volume of 0.2-1.2 ml/g, preferably 0.2-0.6 ml/g, more preferably 0.2-0.45 ml/g, measured according to DIN66134, and/or a mass-specific surface area of 35-400 m.sup.2/g, preferably 75-375 m.sup.2/g, measured according to DIN ISO 9277.
3. The catalyst pellet according to claim 1, wherein the (earth) alkali metal oxide of component (i) is obtainable by calcining the respective (earth) alkali hydroxide, (earth) alkali carbonate, (earth) alkali nitrate, (earth) alkali sulfate, (earth) alkali acetate, (earth) alkali oxalate, (earth) alkali phosphate, in particular the respective (earth) alkali hydroxide, wherein the calcination preferably takes place at 300-900? C., more preferably at 350-650? C., and preferably continues for 10-240 min, more preferably for 60-210 min, even More preferably for 90-150 min, and wherein the calcination preferably takes place under an air, oxygen or inert gas atmosphere.
4. The catalyst pellet according to claim 1, further comprising, (iii) at least one oxide of an element of the 3.sup.rd to 12.sup.th main groups or of the lanthanides, preferably in a proportion by weight of 1-50 wt %, more preferably 5-30 wt % and most preferably 5-25 wt % based on the (earth) alkali metal oxide of component (i).
5. A method of producing a catalyst pellet according to claim 1, comprising: a) providing an (earth) alkali hydroxide, an (earth) alkali carbonate, an (earth) alkali nitrate, an (earth) alkali sulfate, an (earth) alkali acetate, an (earth) alkali oxalate, an (earth) alkali phosphate or a mixture thereof and optionally at least one hydroxide, carbonate, nitrate, sulfate, acetate, oxalate or phosphate of an element of the 3.sup.rd to 12.sup.th main groups or of the lanthanides as a starting material, b) b1) optionally applying the starting material to a carrier material, or b2) optionally mixing the starting material with at least one binding agent, c) providing the starting material or the mixture obtained after b1) or b2) as a pellet precursor, e.g. by extrusion or 3D printing, d) optionally drying of the pellet precursor obtained after c) and e) calcining the pellet precursor obtained after c) or d) to produce the catalyst pellet, wherein the calcining is carried out, for example, under air, oxygen or inert gas atmosphere, preferably at 300-900? C., more preferably at 350-650? C., and preferably lasts for 10-240 min, more preferably for 60-210 min.
6. A catalyst pellet obtainable by a method according to claim 5.
7. A method using the catalyst pellet according to claim 1 for anionic polymerization, in particular for polymerization of cyclic and linear organosiloxanes, and/or for equilibration of organopolysiloxanes.
8. A method for the anionic polymerization of organosiloxanes and/or for equilibration of organopolysiloxanes by converting (A) organocyclosiloxanes of general formula (I) ##STR00022## in particular octamethylcyclotetrasiloxane, and/or linear block organopolysiloxanes of general formula (H), ##STR00023## and linear, random or alternating organopolysiloxanes having the molecular formula of general formula (II) in particular hexamethyldisiloxane, and optionally a compound of general formula (III) ##STR00024## in particular (3-aminopropyl)dimethoxyrnethylsilane, 3-aminopropyl)trimethoxymethylsilane, [N-(2-aminoethyl)-3-aminopropyl)dimethoxymethylsilane, [N-(2-aminoethyl)-3-aminopropyl)trimethoxymethylsilane, with (B) an initiator of general formula (IV) ##STR00025## in particular butanol or trimethylsilanol, wherein R independently of each other is a monovalent, optionally substituted C.sub.1-C.sub.30 hydrocarbon residue, R.sup.1 independently of each other is a monovalent, optionally substituted C.sub.1-C.sub.30 hydrocarbon residue or a polyether residue, f is an integer from 1 to 10, preferably an integer from 1 to 4, in particular 2, g is 0 or 1, h is 0 or an integer from 1 to 1000, preferably from 5 to 800, I is 0 or an integer from 1 to 1000, preferably from 5 to 800, j is 0 or 1, with the proviso that at least one of g, h, i, or j?0 R.sup.2 is a hydroxy group or OR.sup.3, R.sup.3 is a monovalent C.sub.1-C.sub.30 hydrocarbon residue, R.sup.4 for k?1 is a monovalent C.sub.1-C.sub.30 hydrocarbon residue or R.sup.1 and for k?1 is independently of each other a monovalent C.sub.1-C.sub.30 hydrocarbon residue, R.sup.5 is a hydrogen or a monovalent C.sub.1-C.sub.30 hydrocarbon residue, X independently of each other is a monovalent C.sub.1-C.sub.30 hydrocarbon residue or a functionalized residue, K is an integer from 1 to 500, preferably from 1 to 400, more preferably from 1 to 300, R.sup.6 is R or hydrogen, R.sup.7 is R or hydrogen, l is 0 or 1, with the proviso that when l=0, R.sup.6 and/or R.sup.7 must be a hydrogen and when l?0, R.sup.7 must be a hydrogen and R.sup.6 must be R, and m is 0 or an integer front 1 to 100, in particular from 5 to 80 (C) in the presence of at least one catalyst pellet according to claim 1, (D) optionally in the presence of a solvent, preferably xylene, toluene, cyclohexane, heptane, octane, nonane or mixtures thereof, and (E) optionally in the presence of a phase transfer catalyst, in particular benzyltriethylammonium chloride, crown ether, polyethylene glycol diethyl ether or tertiary amines such as 4-dimethylaminopyridine or N,N-dimethylcyclohexylamine.
9. The method according to claim 8, wherein the method is performed continuously.
10. The method according to claim 8, wherein the catalyst (C) is present in an immobilized state.
11. The method according to claim 8, wherein the polyether moiety is selected from a block polyether of general formula (V): ##STR00026## wherein R.sup.8 is a monovalent, optionally substituted, C.sub.1-C.sub.30 hydrocarbon residue, n is 0 or an integer from 2-30, o is 0 or an integer between 1-50, p is 0 or an integer from 1-50, and q is 0 or an integer from 1-50, and a random or alternating polyether having the molecular formula of general formula (V).
12. The method according to claim 8, wherein a functionalized residue X is selected from general formula (VI): ##STR00027## wherein R.sup.9 is R, a hydrogen or an acyl residue; preferably a hydrogen, R.sup.10 is R or a hydrogen, preferably hydrogen, R.sup.11 is R, a hydrogen or an acyl residue, preferably hydrogen. r is an integer from 2-3 s is an integer from 1-3 t is 0 or an integer from 1 to 4, preferably 0 to 1.
13. The method according to claim 8, wherein the molar ratio of the initiator of general formula (IV) to compounds of formula (I) and/or (II) is between 0.003-1:1.
14. The method according to claim 8, wherein the conversion is carried out in a. tubular reactor, fixed bed reactor or loop reactor, preferably in a temperature range of 60-200? C., and preferably with a weight hourly space velocity in the range of 1-30 h.sup.?1.
15. An organopolysiloxane obtainable by a method according to claim 8.
Description
BRIEF DESCRIPTION OF DRAWINGS
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EMBODIMENTS
1. Preparation of the Catalyst
1.1 Preparation of the Powdered Catalyst
[0178] 10 g of powdered magnesium hydroxide was weighed into a crucible and dried at 80 and 120? C. for 1 hour each. The dried magnesium hydroxide was then calcined under static air at a temperature range of 400 to 700? C. for a period of 10 to 240 minutes. The magnesium oxide thus obtained was stored under airtight conditions.
1.2 Preparation of the Catalyst Pellets
[0179] 7.5 g of sodium bentonite was blended with 135 g of demineralized water and suspended with a dispersion disk at 2000 rpm for 2 hours. 142.5 g of magnesium hydroxide was added to the suspension. Using an anchor stirrer, the mixture was processed to a homogeneous paste. By extrusion, the paste was processed to extrudates having diameters of 3 mm. These were then dried at 80 and 120? C. for 1 hour each. A sieve fraction in the range of 2-5 mm in the length of the particles was obtained by crushing and sieving the dried extrudates. The sieve fraction thus obtained was then calcined at a temperature range of 300 to 700? C. for a time period of 5 to 180 minutes under static air. The calcined extrudates thus obtained were stored in an airtight manner.
[0180] Beside the extrudates of Mg(OH).sub.2, pellets were formed from a mixture of Mg(OH).sub.2 and La(OH).sub.3. The weight ratio of the oxides La.sub.2O.sub.3:MgO was 1:9. The amount of inorganic binding agent sodium bentonite was 10% based on the starting material La(OH).sub.3 and Mg(OH).sub.2. The extrudates were prepared as described above. Calcination was carried out under static air for 180 minutes at 500? C. In the following, the catalyst pellets produced in this way are referred to as MgLaONaBe500.
1.3 Effect of Calcination
[0181] In order to examine the impact of calcination on the catalytic ability of metal oxides towards the polymerization and/or equilibration of siloxanes, untreated magnesium oxide was compared with calcined magnesium oxide. The used magnesium oxide had a purity of 99.995%. Calcination was carried out at 600? C. for 3 h under static air (MgO600). In the following, the untreated and the calcined magnesium oxide were dried at 80? C. and then at 120? C. for 1 h each. In each case, 0.5 g of the magnesium oxide samples were weighed into a reaction vessel, mixed with 0.5 g of demineralized water and 50 g of octamethylcyclotetrasiloxane, and stirred. The reaction temperature was 100? C. After 2 h, the conversion control was made by determining the dry substance The conversions obtained were 0.22% for the untreated MgO and 17.35% for MgO600 (
2. Characterization of the Powdered Catalyst
[0182] Powdered magnesium oxide was prepared according to 1.1. The magnesium oxide was calcined at 400, 500, 600 and 700? C. In each case, the calcination time was 3 h. The catalysts thus prepared were referred to as MgO400, MgO500, MgO600 and MgO700 according to their calcination temperature.
2.1 Pore Size Distribution and Pore Volume
[0183] The pore size distribution (total pore volume TPV) and the pore volume were determined via N.sub.2 physisorption with a Nova 4000e analyzer from Quantachrome Instruments. After weighing the catalyst into the measuring cell, the sample was degassed for 3 h at 120? C. under vacuum. Subsequently, the adsorption and desorption isotherms were measured at a constant temperature of 77 K with the aid of liquid nitrogen. The pore size distribution and the pore volume were calculated by using the Barett, Joyner and Halenda (BJH) method (DIN 66134).
[0184] The impact of the calcination temperature on the pore size distribution (total pore volume TPV) and the pore volume is shown in
2.2 Mass Specific Surface
[0185] The determination of the mass specific surface area (Sm) was carried out via N.sub.2 physisorption using a Nova 4000e analyzer from Quantachrome Instruments. After weighing the catalyst into the measuring cell, the sample was degassed for 3 h at 120? C. under vacuum. Subsequently, the adsorption isotherm was measured at a constant temperature of 77 K with the aid of liquid nitrogen. The Brunauer-Emmett-Teller (BET) method (DIN ISO 9277) was used to measure and calculate the mass-specific surface area.
[0186] The results are shown in
2.3 Production of Magnesium Oxide as a Function of Calcination Time
[0187] The effect of calcination time on magnesium hydroxide at a calcination temperature of 400? C. was examined via infrared measurement. The bands of pure and for 1, 2 and 3 h calcined magnesium hydroxide are shown in
2.4. Conversion
[0188] In order to test the activity of the prepared magnesium oxide powders as catalysts for the polymerization and/or equilibration of organosiloxanes, in a first step the powders prepared according to 1.1. were dried at 120? C. for 2 h. This provided for a uniform water content of 0.3%, which served as initiator. Next, 0.5 g of magnesium oxide was mixed with 75 g of octamethylcyclotetrasiloxane (OMCTS) and stirred at 100? C. After 2 h, the magnesium oxide was filtered off and the conversion was determined via the dry substance.
[0189] Surprisingly, the highest conversions were obtained with magnesium oxide calcined at 400 and at 500? C. (
3. Characterization of the Catalyst Pellets
[0190] The used catalyst pellets were prepared according to 1.2. The pellets were calcined at 400, 500 and 600? C. In each case, the calcination time was 3 h. The catalyst pellets thus prepared were referred to as MgNaBe400, MgNaBe500 and MgNaBe600 according to their calcination temperature.
3.1 Mass Specific Surface
[0191] The determination of the mass specific surface area (Sm) was carried out via N.sub.2 physisorption using a Nova 4000e analyzer from Quantachrome Instruments. After weighing the catalyst pellets into the measuring cell, the samples were degassed for 3 h at 120? C. under vacuum. Subsequently, the adsorption isotherm was measured at a constant temperature of 77 K with the aid of liquid nitrogen. The Brunauer-Emmett-Teller (BET) method (DIN ISO 9277) was used to measure and calculate the mass-specific surface area.
[0192] Mass specific surface areas of 71.99 m.sup.2/g for MgNaBe400, 64.40 m.sup.2/g for MgNaBe500 and 44.82 m.sup.2/g for MgNaBe600 could be measured.
3.2 Pore Size Distribution and Pore Volume
[0193] The pore volume and pore size distribution were determined by mercury porosimetry according to DIN 66133. Before measurement, the extrudates were dried for 1 h at 120? C. and cooled to room temperature in a desiccator.
[0194] Pore volumes of 0.758 ml/g for MgNaBe400, 0.827 ml/g for MgNaBe500 and 0.746 ml/g for MgNaBe600 could be determined. The mean pore radius was 0.217 ?m for MgNaBe400, 0.220 ?m for MgNaBe500 and 0.201 ?m for MgNaBe600.
3.3. Temperature-Programmed Desorption of CO.SUB.2 .as a Measure of Base Strength
[0195] Via CO.sub.2 adsorption, the base strength of the catalyst pellets prepared in 1.2. was examined. First, the samples were baked out under a helium atmosphere. The bake-out temperature was based on the calcination temperature. For the pellets calcined at 500 and 600? C., respectively, the bakeout temperature was 480? C., whereas for the pellets calcined at 400? C., the bakeout temperature was 400? C. In the following, CO.sub.2 adsorption was carried out in a 100% CO.sub.2 atmosphere at room temperature, followed by a purging process in order to remove lightly adsorbed CO.sub.2 from the surface. Over a temperature ramp of 10? C./min, the desorption of CO.sub.2 was now determined by a downstream gas chromatography.
[0196] The results for the pellets prepared in 1.2. are shown in
[0197] By use of the Arrhenius and Kissinger equations (see Leon et al.), the CO.sub.2 desorption enthalpies were determined. These were 59 kJ/mol for a bakeout temperature at 100? C., 90 kJ/mol at 175? C., and 200 kJ/mol at 450? C.
4. Fixed Bed Reactor
[0198] In order to test the catalyst characterized in item 2. under continuous reaction conditions, it was brought into pellet form as described under 1.2. in order to avoid an increased pressure loss in the fixed bed. The used sodium bentonite did not show catalytic activity towards the polymerization and/or equilibration of siloxanes, so that magnesium oxide can be assumed as the catalytic species.
[0199] The used reactor consisted of 4 modular stainless steel tubes connected in series having an inner diameter of 1.2 cm and a height of 50 cm, which corresponds to a total reaction volume of 56 cm.sup.3 per column. The catalyst volume corresponded to a total of 50 cm.sup.3 per column. The fixed bed could be heated via a heating jacket in a temperature range of 25 to 200? C. The reaction temperature was 80 to 160? C. and the WHSV was varied in a range from 10 to 30 h.sup.?1. The educt solution of different compositions was fed into the reactor via a gear pump.
EXAMPLE 1
[0200] A reactant solution consisting of 483.6 g of octamethylcyclotetrasiloxane with 16.4 g of 1-butanol was continuously pumped into the fixed bed with a WHSV of 3 h.sup.?1. As the fixed bed, 10 g of the catalyst MgONaBe600 prepared in 1.2 was used. The temperature of the fixed bed was maintained at 140? C. The product was concentrated on the rotary evaporator at 140? C. and 5 mbar. A clear colorless oil having a viscosity of 150 mPas at 25? C. was obtained and corresponded to a silicone of the following formula according to the results of the .sup.29Si and .sup.1H-NMR spectrum (
##STR00010##
EXAMPLE 2
[0201] A reactant solution consisting of 270 g of octamethylcyclotetrasiloxane, 30 g of 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane and 6.12 g of trimethylsilanol was continuously pumped into the fixed bed with a WHSV of 6 h.sup.?1. As the fixed bed, 10 g of the catalyst MgONaBe600 prepared in 1.2 was used. The temperature of the fixed bed was maintained at 140? C. A clear colorless oil having a viscosity of 130 mPas at 25? C. was obtained and corresponded to a silicone of the following formula according to the results of a .sup.29Si and .sup.1H-NMR spectrum:
##STR00011##
EXAMPLE 3
[0202] A reactant solution consisting of 117 g of octamethylcyclotetrasiloxane, 12 g of a 3-aminopropyldiethoxysilane and 110 g of an ?,?-dihydroxypolydimethylsiloxane was continuously pumped into the fixed bed with a WHSV of 6 h.sup.?1. As the fixed bed, 10 g of the catalyst MgONaBe600 prepared in 1.2 was used. The temperature of the fixed bed was maintained at 140? C. The product is a clear colorless oil having a viscosity of 130 mPas at 25? C. and corresponds to a silicone of the following formula according to the results of a .sup.29Si and .sup.1H-NMR spectrum:
##STR00012##
EXAMPLE 4
[0203] A reactant solution consisting of 483.6 g of octamethylcyclotetrasiloxane, 16.4 g of 1-butanol and 10 g of dimethyl sulfoxide were continuously pumped into the fixed bed with a WHSV of 3 h.sup.?1. As the fixed bed 10 g of the catalyst MgONaBe600 prepared in 1.2 was used. The temperature of the fixed bed was maintained at 140? C. It was found that by using dimethyl sulfoxide, the residence time could be reduced by 30% compared to Example 1. The product thus obtained was concentrated on the rotary evaporator at 140? C. and 5 mbar. A clear colorless oil having a viscosity of 150 mPas at 25? C. was obtained and corresponded to a silicone of the following formula according to the results of the .sup.29Si and .sup.1H-NMR spectrum:
##STR00013##
The proportion by weight of dimethyl sulfoxide in the product after distillation was less than 0.05%.
EXAMPLE 5
[0204] An educt solution, as in Example 1, consisting of 483.6 g of octamethylcyclotetrasiloxane with 16.4 g of 1-butanol was provided. As the fixed bed, 10 g of the catalyst MgLaONaBe500 prepared in 1.2. was used. The temperature of the fixed bed was maintained at 140? C. The WHSV at which the input stream was pumped into the fixed bed could be increased from 3 to 6 h.sup.?1 compared to Example 1 to still obtain the same conversions as in Example 1. The product was concentrated on the rotary evaporator at 140? C. and 5 mbar. A clear colorless oil having a viscosity of 150 mPas at 25? C. was obtained and corresponded to a silicone of the following formula according to the results of the .sup.29Si and .sup.1H-NMR spectrum:
##STR00014##
EXAMPLE 6
[0205] In order to determine the contribution of condensation reactions to the polymerization reactions, a pure ?,?-dihydroxypolydimethylsiloxane was passed through the fixed bed. Due to the hydroxy groups at the terminal ends of the siloxane, water would be cleaved off during polycondensation.
[0206] By means of Karl Fischer titration the water content of the undistilled product was analyzed.
[0207] For this purpose, a reactant solution consisting of 500 g of an ?,?-dihydroxypolydimethylsiloxane was provided. The water content of the reactant solution, determined according to ISO 760, was 0.16%. As a fixed bed, 10 g of the catalyst MgONaBe600 prepared in 1.2. was used. The temperature of the fixed bed was maintained at 80? C. The WHSV at which the input stream was pumped into the fixed bed was 3 h.sup.?1. An undistilled, clear colorless oil was obtained, which had a water content of 0.07%. It corresponded to a silicone of the following formula according to the results of the .sup.29Si and .sup.1H-NMR spectrum:
##STR00015##
[0208] From the reduced amount of water in the final product, it can be concluded that part of the water acted as an initiator, but essentially no condensation reaction occurred.
[0209] The present invention is defined by the following items: [0210] 1. A catalyst pellet for anionic polymerization of organosiloxanes and/or for equilibration of organopolysiloxanes comprising [0211] (i) at least one (earth) alkali metal oxide and [0212] (ii) optionally at least one binding agent or at least one carrier material, characterized in that the CO.sub.2 desorption enthalpy of the catalyst pellet is 25-350 kJ/mol, preferably 50-300 kJ/mol and particularly preferably from 50-200 kJ/mol, measured by temperature programmed desorption of CO.sub.2. [0213] 2. The catalyst pellet according to item 1, wherein the (earth) alkali metal oxide (i) is sodium oxide, potassium oxide, rubidium oxide, cesium oxide, beryllium oxide, magnesium oxide, calcium oxide, strontium oxide or barium oxide, in particular calcium oxide or magnesium oxide, particularly preferred magnesium oxide. [0214] 3. The catalyst pellet according to any one of the preceding items, wherein the (earth) alkali metal oxide (i) has a mean pore radius of 2-130 nm, preferably 2-65 nm, more preferably 2-35 nm, measured according to DIN 66134. [0215] 4. The catalyst pellet according to any one of the preceding items, wherein the (earth) alkali metal oxide of component (i) has a specific pore volume of 0.2-1.2 ml/g, preferably 0.2-0.6 ml/g, more preferably, 0.2-0.45 ml/g, measured according to DIN 66134. [0216] 5. The catalyst pellet according to any one of the preceding items, wherein the (earth) alkali metal oxide of component (i) has a mass specific surface area of 35-400 m.sup.2/g, preferably 75-375 m.sup.2/g, more preferably 125-350 m.sup.2/g, measured according to DIN ISO 9277. [0217] 6. The catalyst pellet according to any one of the preceding items, wherein the proportion by weight of component (i) based on the total weight of the catalyst pellet is 0.1-100 wt %, preferably 1-100 wt %, more preferably 10-100 wt %, even more preferably 20-99.9 wt %, and most preferably 50-99.9 wt %. [0218] 7. The catalyst pellet according to item 2, wherein the (earth) alkali metal oxide magnesium oxide in an X-ray diffraction pattern (Cu-K.sub.?: 0.154056 nm) has the five strongest signals at 2?=37?, 43?, 62?, 75? and 78?, and the (earth) alkali metal oxide calcium oxide in an X-ray diffraction pattern (Cu-K.sub.?: 0.154056 nm) has the six strongest signals at 2?=32?, 37?, 53?, 64?, 67? and 79?. [0219] 8. The catalyst pellet according to any one of the preceding items, wherein the (earth) alkali metal oxide of component (i) is obtainable by calcination of the respective (earth) alkali hydroxide, (earth) alkali carbonate, (earth) alkali nitrate, (earth) alkali sulfate, (earth) alkali acetate, (earth) alkali oxalate, (earth) alkali phosphate, in particular the respective (earth) alkali hydroxide. [0220] 9. The catalyst pellet according to item 8, wherein calcination takes place at 300-900? C., preferably at 350-650? C., more preferably at 375-550? C., and preferably continues for 10-240 min, more preferably for 60-210 min, even more preferably for 90-150 min. [0221] 10. The catalyst pellet according to item 8 or 9, wherein calcination takes place under air, oxygen or inert gas atmosphere. [0222] 11. The catalyst pellet according to any one of the preceding items, wherein the binding agent of component (ii) is selected from organic or inorganic binding agents, preferably layered silicate, such as bentonite, sodium silicate, sodium aluminate, aluminosilicate, silica and esters thereof, as well as brines or colloidal solutions of silicon dioxide and, in a preferred embodiment, is catalytically inert. [0223] 12. The catalyst pellet according to any one of the preceding items, wherein the carrier material of component (ii) is selected from aluminium oxid, zirconium oxide, silicon dioxide, titanium oxide, titanium dioxide, metal phosphate such as hydroxyapatite, cerium oxide and carbon, and mixed oxides such as, for example, SiO.sub.2Al.sub.2O.sub.3, SiO.sub.2TiO.sub.2, ZrO.sub.2SiO.sub.2, ZrO.sub.2Al.sub.2O.sub.3 or mixtures of two or more of these materials. [0224] 13. The catalyst pellet according to any one of the preceding items, wherein the binding agent of component (ii) constitutes 0-40 wt %, preferably 0-20 wt %, more preferably 0.1-15 wt %, and more preferably 2-10 wt % based on the total weight of the catalyst pellet. [0225] 14. The catalyst pellet according to any one of the preceding items, wherein the carrier material of component (ii) constitutes 0-99.9 wt %, more preferably 0-80 wt %, and further preferably 0-50 wt % based on the total weight of the catalyst pellet. [0226] 15. The catalyst pellet according to any one of the preceding items, further comprising [0227] (iii) at least one oxide of an element of 3.sup.rd to 12.sup.th main groups or of the lanthanides, preferably in a proportion by weight of 1-50%, more preferably 5-30% and most preferably 5-25%, based on the (earth) alkali metal oxide of component (i). [0228] 16. The catalyst pellet according to any one of the preceding items, wherein the water content is 0.01-0.5 wt % based on the total weight of the catalyst pellet. [0229] 17. A method for preparing a catalyst pellet according to any one of items 1-16, comprising the steps: [0230] a) providing an (earth) alkali hydroxide, an (earth) alkali carbonate, an (earth) alkali nitrate, an (earth) alkali sulfate, an (earth) alkali acetate, an (earth) alkali oxalate, an (earth) alkali phosphate or a mixture thereof and optionally at least one hydroxide, carbonate, nitrate, acetate, oxalate, phosphate or sulfate of an element of the 3.sup.rd to 12.sup.th main groups or of the lanthanides as a starting material, [0231] b) [0232] b1) optionally, applying the starting material to a carrier material, or [0233] b2) optionally, mixing the starting material with at least one binding agent, [0234] c) providing the starting material or the mixture obtained after step b1) or b2) as a pellet precursor, [0235] d) optionally, drying of the pellet precursor obtained after step c) and [0236] e) calcining the pellet precursor obtained after step c) or d) in order to produce the catalyst pellet. [0237] 18. The method according to item 17, wherein the pellet precursor comprises [0238] 1-100 wt % starting material, [0239] 0-20 wt % binding agent or [0240] 0-99 wt % carrier material, [0241] based on the total weight of the pellet precursor. [0242] 19. The method according to item 17 or 18, wherein the amount of solvent after step b) is 0-99 wt %, preferably 10-90 wt %, based on the total weight of the mixture. [0243] 20. The method according to any one of items 17-19, wherein step (c) is carried out by means of granulating, pressing, extruding, 3D printing, tabletting and spray drying the mixture obtained according to b). [0244] 21. The method according to any one of items 17-20, wherein the solvent content after step c) or d) is 0-10 wt % based on the total weight of the pellet precursor. [0245] 22. The method according to any one of items 17-21, wherein calcination in step e) is carried out at 300-900? C., preferably at 350-650? C., more preferably at 375-550? C., and preferably continues for 10-240 min, more preferably for 60-210 min, even more preferably for 90-150 min. [0246] 23. The method according to any one of items 17-22, wherein step e) is carried out under an air, oxygen, or inert gas atmosphere. [0247] 24. The catalyst pellet obtainable by a method according to any one of items 17-23. [0248] 25. The use of a catalyst pellet according to any one of items 1-16 or 24 for anionic polymerization of organosiloxanes and/or for equilibration of organopolysiloxanes. [0249] 26. A method for the anionic polymerization of organosiloxanes and/or for the equilibration of organopolysiloxanes by converting [0250] (A) organocyclosiloxanes of general formula (I)
##STR00016## and/or linear block organopolysiloxanes of general formula (II)
##STR00017## and linear, random or alternating organopolysiloxanes having the molecular formula of general formula (II), [0251] and optionally a compound of general formula (III)
##STR00018## [0252] with [0253] (B) an initiator of general formula (IV)
##STR00019## wherein [0254] R independently of each other is a monovalent, optionally substituted C.sub.1-C.sub.30 hydrocarbon residue, [0255] R.sup.1 independently of each other is a monovalent, optionally substituted C.sub.1-C.sub.30 hydrocarbon residue or a polyether residue, [0256] f is an integer from 1 to 10, preferably an integer from 1 to 4, in particular 2, [0257] g is 0 or 1, [0258] h is 0 or an integer from 1 to 1000, preferably from 5 to 800, [0259] i is 0 or an integer from 1 to 1000, preferably from 5 to 800, [0260] j is 0 or 1, [0261] with the proviso that at least one of g, h, i, or j?0. [0262] R.sup.2 is a hydroxy group or OR.sup.3, [0263] R.sup.3 is a monovalent C.sub.1-C.sub.30 hydrocarbon residue, [0264] R.sup.4 for k=1 is a monovalent C.sub.1-C.sub.30 hydrocarbon residue or R.sup.1, and [0265] for k?1 is independently of each other a monovalent C.sub.1-C.sub.30 hydrocarbon residue, [0266] R.sup.5 is a hydrogen or a monovalent C.sub.1-C.sub.30 hydrocarbon residue, [0267] X independently of each other is a monovalent C.sub.1-C.sub.30 hydrocarbon residue or a functionalized residue, [0268] k is an integer from 1 to 500, preferably from 1 to 400, more preferably from 1 to 300, [0269] R.sup.6 is R or hydrogen, [0270] R.sup.7 is R or hydrogen, [0271] l is 0 or 1, [0272] with the proviso that when l=0, R.sup.6 and/or R.sup.7 must be a hydrogen and when l?0, R.sup.7 must be a hydrogen and R.sup.6 must be R, and [0273] m is 0 or an integer from 1 to 100, in particular from 5 to 80 [0274] (C) in the presence of at least one catalyst pellet according to any one of items 1-16 or 24, [0275] (D) optionally in the presence of a solvent, and [0276] (E) optionally in the presence of a phase transfer catalyst. [0277] 27. The method according to item 26, wherein the method is carried out continuously. [0278] 28. The method according to any one of items 26-27, wherein the catalyst (C) is present in a different aggregate state than components (A), (B), and (D). [0279] 29. The method according to any one of items 26-28, wherein the catalyst (C) is present in an immobilized state. [0280] 30. The method according to any one of items 26-29, wherein the polyether residue is selected from a block polyether of general formula (V):
##STR00020## wherein [0281] R.sup.8 is a monovalent, optionally substituted C.sub.1-C.sub.30 hydrocarbon residue, [0282] n is 0 or an integer from 2-30, [0283] o is 0 or an integer between 1-50, [0284] p is 0 or an integer from 1-50, and [0285] q is 0 or an integer from 1-50, [0286] and a random or alternating polyether having the molecular formula of general formula (V). [0287] 31. The method according to any one of items 26-30, wherein a functionalized residue X is selected from general formula (VI):
##STR00021## wherein [0288] R.sup.9 is R, a hydrogen or an acyl residue, preferably a hydrogen, [0289] R.sup.10 is R or a hydrogen, preferably hydrogen, [0290] R.sup.11 is R, a hydrogen or an acyl residue, preferably hydrogen, [0291] r is an integer from 2-3 [0292] s is an integer from 1-3 [0293] t is 0 or an integer from 1 to 4, preferably 0 to 1. [0294] 32. The method according to any one of items 26-31, wherein the organocyclosiloxane of general formula (I) is octamethylcyclotetrasiloxane. [0295] 33. The method according to any one of items 26-32, wherein the organopolysiloxane of general formula (II) is preferably polydimethylsiloxane, e.g. hexamethyldisiloxane. [0296] 34. The method according to any one of items 26-33, wherein a compound of general formula (III) is (3-aminopropyl)dimethoxymethylsilane, (3-aminopropyl)trimethoxymethylsilane, [N-(2-aminoethyl)-3-aminopropyl)dimethoxymethylsilane, [N-(2-aminoethyl)-3-aminopropyl)trimethoxymethylsilane. [0297] 35. The method according to any one of items 26-34, wherein the initiator of general formula (IV) is butanol or trimethylsilanol. [0298] 36. The method according to any one of items 26-35, wherein the molar ratio of the initiator of general formula (IV) to compounds of formula (I) and/or (II) is between 0.003-1:1. [0299] 37. The method according to any one of items 26-36, wherein the solvent (D) is a non-polar organic solvent, preferably xylene, toluene, cyclohexane, heptane, octane, nonane or mixtures thereof. [0300] 38. The method according to any one of items 26-37, wherein the phase transfer catalyst (E) is benzyltriethylammonium chloride, crown ether, polyethylene glycol diethyl ether, or tertiary amines such as 4-dimethylaminopyridine or N,N-dimethylcyclohexylamine. [0301] 39. The method according to any one of items 26-38, wherein the conversion is carried out in a tubular reactor, fixed bed reactor, or loop reactor. [0302] 40. The method according to any one of items 26-39, wherein the conversion is carried out in a temperature range of 60-200? C., preferably 80-180? C. [0303] 41. The method according to any one of items 26-40, wherein the reaction is carried out at a weight hourly space velocity in the range of 1-30 h.sup.?1, preferably 3-30 h.sup.?1, more preferably 3-24 h.sup.?1. [0304] 42. An organopolysiloxane obtainable by a method according to any one of items 26-41.