CN108456300A - A kind of catalyst and preparation method thereof of controllable polyethylene glycol oxide molecular weight - Google Patents

Abstract

The invention relates to a catalyst capable of regulating the molecular weight of polyethylene oxide and a preparation method thereof. The ammonia-calcium complex solution is formed by reacting liquid ammonia and metallic calcium at a low temperature of -80°C to -10°C for 0.5h to 4h, and adding the The modifying agent composed of oxypropane and azo compounds continues to react in the solvent for 0.5h to 4h, and undergoes deamination and aging treatment by raising the temperature to obtain the catalyst. Compared with the prior art, the catalyst prepared by the present invention has the advantages of high activity, high stability, adjustable polymer molecular weight, etc., and can be prepared in the ring-opening polymerization of ethylene oxide (English abbreviation: EO). Produce a series of polyethylene oxide products with a molecular weight between 100,000 and 2 million.

Description

A catalyst capable of regulating the molecular weight of polyethylene oxide and its preparation method

technical field

The invention relates to a catalyst, in particular to a method for preparing a catalyst for catalyzing the ring-opening polymerization of ethylene oxide to generate polyethylene oxide, which can synthesize a series of polyethylene oxide with a molecular weight of 100,000 to 2 million.

Background technique

Polyethylene oxide (PEO) is a linear polymer formed by heterogeneously catalyzed ring-opening polymerization of ethylene oxide. It is a crystalline, thermoplastic, and water-soluble polymer with low chemical toxicity. Depending on the degree of polymerization, the molecular weight of polyethylene oxide can vary from 100,000 to 8 million. In addition to the above properties, PEO also has a series of other excellent properties at different molecular weights, and can act as a dispersant, flocculant, thickener, hydraulic drag reducer, etc. It is widely used in many fields such as medicine and industrial engineering. In recent years, with the increasing application range of polyethylene oxide, the application of low molecular weight polyethylene oxide has been further expanded, and the market demand has gradually increased.

The key technology of polyethylene oxide synthesis is the development of high-efficiency catalysts. Currently common polyethylene oxide catalyst systems include metal alkyl catalyst systems, metal alkoxide catalyst systems and alkaline earth metal amide catalyst systems. The molecular weight of polyethylene oxide prepared by catalysts of different systems is also different. The U.S. patent (US2006036066) mentions the blending of organoaluminum compounds and alkali metal oxides or hydroxides, and the obtained catalyst can prepare polyethylene oxide with a molecular weight of 20,000 to 200,000. However, the process is complicated and involves high-pressure operation. Equipment requirements are high. Chinese patent (CN 1306023A) is a catalyst synthesized by dissolving metal calcium in liquid ammonia, adding modifiers and aluminum oxide and other carriers. The catalyst has the characteristics of low temperature, high activity and high yield. The prepared polyoxygen The molecular weight of ethylene reaches 8 million, which is not suitable for the preparation of low molecular weight PEO products. Shanghai Research Institute of Chemical Industry has a number of patents (CN101392053A, CN 101407579A, etc.) for the synthesis of medium and low molecular weight polyethylene oxide. The catalysts reported are mainly alkaline earth metal-ammonia-modifier systems, wherein the alkaline earth metals are calcium and strontium Etc., the modifier is alkylene oxide, organic nitrile or organic amine, or the catalyst is supported on nano-silica or mesoporous molecular sieve carrier, and the synthesized catalyst is stable. But the catalytic stability of the catalyst mentioned in the patent CN 101392053A is relatively poor, and the polymerization yield of ethylene oxide fluctuates between 60%～98%; The catalyst mentioned in the patent (CN 101407579A) can only prepare molecular weight is 80 Polyethylene oxide between 10,000 and 3 million cannot be synthesized with lower molecular weight polyethylene oxide. Chinese patent (CN 103539931 A) reported alkaline earth metal calcium-ammonia-modifier catalyst system, the modifier is composed of propylene oxide and acetonitrile, and aging treatment is carried out to the suspension catalyst, and the prepared molecular weight is between 600,000 PEO between 1.6 million and 1.6 million, but the catalyst prepared by this patent cannot synthesize PEO with molecular weight between 100,000 and 600,000.

Based on the ammonia-calcium catalyst system, the present invention develops a new modifier formula composed of azo compounds and propylene oxide by adjusting the type of modifier, and prepares an ammonia-calcium catalyst with adjustable polymer molecular weight, and can By changing the type and amount of azo compounds to adjust the activity of the catalyst, a series of low and medium molecular weight polyethylene oxides with a molecular weight between 100,000 and 2,000,000 were synthesized.

Contents of the invention

The object of the present invention is to provide a catalyst capable of regulating the molecular weight of polyethylene oxide and a preparation method thereof in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions: a method for preparing a catalyst capable of regulating the molecular weight of polyethylene oxide, characterized in that the method comprises the following steps: reacting liquid ammonia and metal calcium at low temperature to generate calcium ammonia The complex solution is added with a modifying agent composed of propylene oxide and azo compounds, then continues to react in a solvent, and undergoes deamination and aging treatment to obtain the catalyst.

The volume-to-mass ratio of the liquid ammonia to metallic calcium is: (75-100): 1ml/g;

The mass ratio of propylene oxide and azo compounds in the modifier is (0.1-30):1;

The mass ratio of the ammonia-calcium complex to the modifier is (0.1-20): 1;

The volume-to-mass ratio of the solvent and the modifying agent is (20-100): 1ml/g.

The low temperature condition is between -80°C and -10°C, the time for the ammonia-calcium complex solution to react to form the ammonia-calcium complex solution is 0.5h-4h, and the reaction time after adding the modifier is 0.5h- 4h.

The azo compounds include: azobisisoheptanonitrile, azobisisobutyronitrile, azobisisovaleronitrile, azodimethylvaleronitrile, azobiscyclohexanenitrile, azobisisobutyronitrile Dimethyl azodicarboxylate, diisopropyl azodicarboxylate, diethyl azodicarboxylate, dimethyl azodicarboxylate, di-tert-butyl azodicarboxylate, azobenzene-4,4'-dicarboxylic acid One or more of dimethyl ester, dibenzyl azodicarboxylate, azodicarbonamide, N,N-diisopropyl azodicarbonamide, and azodicarbonyldimorpholine.

The reaction solvent includes one or more mixtures of n-hexane, cyclohexane, n-heptane, petroleum ether, No. 6 solvent oil, No. 120 solvent oil, and No. 180 solvent oil.

The temperature required for the deamination treatment is in the range of -10°C to 30°C.

The aging treatment temperature is between 40°C and 150°C, and the aging treatment time is between 0.5h and 4h, wherein the aging temperature is preferably within the range of 40°C to 100°C.

During the whole process of catalyst synthesis, the reaction system is always under the protection of inert gas and strictly carried out in an anhydrous and oxygen-free environment.

The polyethylene oxide prepared by the catalyst in catalyzing the ring-opening polymerization of ethylene oxide is a white particle, which can regulate the molecular weight of polyethylene oxide in a wide range, and is especially suitable for the synthesis of low molecular weight PEO. The obtained polyethylene oxide The viscosity average molecular weight is between 100,000 and 2 million.

Compared with the prior art, the modifier used in the catalyst provided by the invention is a mixed solution of azo compounds and propylene oxide, and the activity of the catalyst can be adjusted by changing the type and amount of the azo compounds. The catalyst synthesized by the invention has the characteristics of high activity and high stability, can convert 400g of ethylene oxide per gram of catalyst (calculated as metal), and its polymerization yield is stable above 96%.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

(1) Synthesis of catalyst:

Under the protection of high-purity argon, collect 150ml-200ml of liquid ammonia in a 2000ml four-necked flask at -60°C. Under magnetic stirring, add 2g Ca in the flask, obtain ammoniacal calcium complex after reacting 1h; 2.90g propylene oxide and 1.220g azobicyclohexyl nitrile composition modifying agent are dissolved in 300ml n-hexane, then It is added to the above-mentioned ammonia-calcium complex and reacted for 1 hour; heated to raise the reaction temperature to 0°C to volatilize excess liquid ammonia; finally, raise the reaction temperature to 60°C for aging treatment for 1 hour to obtain a white slurry Catalyst. The whole reaction system was carried out under the protection state of high-purity argon.

(2) Ethylene oxide polymerization reaction:

The above-mentioned slurry catalyst was added to a well-sealed 2L reaction kettle filled with argon with mechanical stirring, and then 300ml of n-hexane and 200g of ethylene oxide were added to the reaction kettle. The polymerization reaction is carried out at 20°C to 30°C for 6h to 12h. The prepared polyoxyethylene is white powdery particles with uniform particle size, the viscosity-average molecular weight of the synthesized PEO is 500,000, and the polymerization yield is 99.6%.

Example 2

(1) Synthesis of catalyst:

The amount of azobicyclohexanenitrile was changed to 0.630g, and other operating procedures were the same as in Example 1.

(2) Ethylene oxide polymerization reaction:

The polymerization operation process is identical with the polymerization operation process of embodiment 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 250,000, and the polymerization yield is 99.8%.

Example 3

(1) Synthesis of catalyst:

The modifying agent is a mixed solution of azobisisobutyronitrile and propylene oxide, and the amount of azobisisobutyronitrile is 0.835 g. Other operating procedures are the same as in Example 1.

(2) Ethylene oxide polymerization reaction:

The polymerization operation process is identical with the polymerization operation process of embodiment 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 440,000, and the polymerization yield is 99.9%.

Example 4

(1) Synthesis of catalyst:

The reaction time of calcium ammonia is 3 hours, and the modifier is a mixed solution of azodimethylvaleronitrile and propylene oxide. Take 1.920 g of azodimethylvaleronitrile, and the aging temperature is 100 ° C. Other operating procedures and examples 1 is the same.

(2) Ethylene oxide polymerization reaction:

The polymerization operation process is identical with the polymerization operation process of embodiment 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 850,000, and the polymerization yield is 100%.

Example 5

(1) Synthesis of catalyst:

The aging condition was set at 60° C. for 3 h, and other operating procedures were the same as in Example 5.

(2) Ethylene oxide polymerization reaction:

The polymerization operation process is identical with the polymerization operation process of embodiment 1. The prepared polyethylene oxide has a viscosity-average molecular weight of 430,000 and a polymerization yield of 99.9%.

Example 6

(1) Synthesis of catalyst:

The modifier is a mixed solution of dimethyl azodicarboxylate and propylene oxide, the amount of dimethyl azodicarboxylate is 1.461g, the aging temperature is 60°C, and the aging time is 4h. Other operations are the same as Example 1 is the same.

(2) Ethylene oxide polymerization reaction:

The polymerization operation process is identical with the polymerization operation process of embodiment 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 140,000, and the polymerization yield is 100%.

Example 7

(1) Synthesis of catalyst:

A mixed solution of dimethyl azodicarboxylate and propylene oxide was selected, and the amount of dimethyl azodicarboxylate was 0.731 g, and other operating procedures were the same as in Example 1.

(2) Ethylene oxide polymerization reaction:

The polymerization operation process is identical with the polymerization operation process of embodiment 1. The prepared polyethylene oxide has a viscosity-average molecular weight of 190,000 and a polymerization yield of 99.1%.

Example 8

(1) Synthesis of catalyst:

The modifier is a mixed solution of N,N-diisopropyl azodicarbonamide and propylene oxide, and the amount of N,N-diisopropyl azodicarbonamide is 0.895g. Other operations and implementation Example 1 is the same.

(2) Ethylene oxide polymerization reaction:

During the polymerization operation, the amount of ethylene oxide added was 400g, and the amount of n-hexane was 600ml. Other polymerization operations were the same as in Example 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 1.13 million, and the polymerization yield is 98.9%.

Example 9

(1) Synthesis of catalyst:

The operating process of the catalyst preparation is the same as that of the catalyst in Example 8.

(2) Ethylene oxide polymerization reaction:

During the polymerization operation, the amount of ethylene oxide added was 600g, the amount of n-hexane was 900ml, and the polymerization reactor was selected from a 10L reactor. Other polymerization operations were the same as in Example 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 1.68 million, and the polymerization yield is 100%.

Example 10

(1) Synthesis of catalyst:

The operating process of the catalyst preparation is the same as that of the catalyst in Example 8.

(2) Ethylene oxide polymerization reaction:

During the polymerization operation, the amount of ethylene oxide added was 800g, the amount of n-hexane was 1200ml, and the polymerization reactor was selected from a 10L reactor. Other polymerization operations were the same as in Example 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 1.92 million, and the polymerization yield is 96%.

Example 11

(1) Synthesis of catalyst:

Select dibenzyl azodicarboxylate azo compounds and propylene oxide as modifiers, take the amount of dibenzyl azodicarboxylate as 2.307g, get 400ml of solvent, the aging temperature is 40°C, and the aging time is 3h, other operating processes are the same as in Example 1.

(2) Ethylene oxide polymerization reaction:

The polymerization operation process is identical with the polymerization operation process of embodiment 1. The viscosity-average molecular weight of the prepared polyethylene oxide is 200,000, and the polymerization yield is 99.6%.

Table 1. Performance table of each embodiment

Example Activity (g-EO/g-Ca) Molecular weight/10,000 Polymerization yield Example 1 100 50 99.6% Example 2 100 25 99.8% Example 3 100 44 99.9% Example 4 100 85 100% Example 5 100 43 99.9% Example 6 100 14 100% Example 7 100 19 99.1% Example 8 200 113 98.9% Example 9 300 168 100% Example 10 400 192 96.1% Example 11 100 20 99.6%

It can be seen from the above examples that the catalyst provided by the present invention has the advantages of high activity, high stability and adjustable polymer molecular weight, and can efficiently prepare polyethylene oxide series products with a molecular weight between 100,000 and 2 million.

Example 12

A method for preparing a catalyst capable of regulating the molecular weight of polyethylene oxide, the method comprising the following steps: under the protection of high-purity helium, reacting liquid ammonia and metal calcium at a low temperature of -10°C for 4 hours to generate ammonia-calcium complexation After adding a modifying agent consisting of propylene oxide and azo compounds, the reaction was continued in the solvent for 0.5 h, deamination treatment at -10° C., and aging treatment at 40° C. for 4 h to obtain the catalyst.

Wherein, the volume-to-mass ratio of the liquid ammonia to metallic calcium is: 75:1ml/g; the mass ratio of propylene oxide and azo compounds in the modifier is 0.1:1; the ammonia-calcium The volume-mass ratio of the complex to the modifier is 0.1:1; the mass ratio of the solvent to the modifier is 20:1.

The azo compound is azobisisoheptanonitrile. Described solvent is n-heptane.

Example 13

A method for preparing a catalyst capable of regulating the molecular weight of polyethylene oxide, the method comprising the following steps: under the protection of high-purity helium, reacting liquid ammonia and metallic calcium at a low temperature of -80°C for 0.5h to generate an ammonia-calcium complex compound solution, adding a modifying agent composed of propylene oxide and azo compounds and continuing to react in the solvent for 4 hours, deamination treatment at 30°C, and aging treatment at 150°C for 0.5h to obtain the catalyst.

Wherein, the volume-to-mass ratio of the liquid ammonia to metallic calcium is: 100:1ml/g; the mass ratio of propylene oxide and azo compounds in the modifier is 30:1; the ammoniacal calcium The volume-mass ratio of the complex compound to the modifier is 20:1; the mass ratio of the solvent to the modifier is 100:1.

The azo compound is azodicarbonyldimorpholine. Said solvent includes n-heptane.

Claims (10)

1. a preparation method of a catalyst capable of regulating the molecular weight of polyethylene oxide, characterized in that the method comprises the following steps: reacting under low temperature conditions by liquid ammonia and metallic calcium to generate ammonia-calcium complex solution, adding propylene oxide After reacting with a modifying agent composed of azo compounds in a solvent, the catalyst is obtained through deamination and aging treatment. 2. The method for preparing a catalyst capable of regulating the molecular weight of polyethylene oxide according to claim 1, wherein the volume-to-mass ratio of the liquid ammonia to metallic calcium is: (75-100): 1ml/g; The mass ratio of propylene oxide and azo compounds in the modifier is (0.1-30):1; The mass ratio of the ammonia-calcium complex to the modifier is (0.1-20): 1; The volume-to-mass ratio of the solvent and the modifying agent is (20-100): 1ml/g. 3. the preparation method of the catalyst that can regulate the molecular weight of polyethylene oxide according to claim 1, is characterized in that, described azo compound comprises: azobisisoheptanonitrile, azobisisobutyronitrile, azo Diisovaleronitrile, azodimethylvaleronitrile, azobicyclohexylnitrile, dimethyl azobisisobutyrate, diisopropyl azodicarboxylate, diethyl azodicarboxylate, azobis Dimethyl formate, Di-tert-butyl azodicarboxylate, Dimethyl azobenzene-4,4'-dicarboxylate, Dibenzyl azodicarboxylate, Azodicarbonamide, N,N-Diisopropyl One or more of azodicarbonylamide and azodicarbonyldimorpholine. 4. the preparation method of the catalyzer of adjustable polyethylene oxide molecular weight according to claim 1 is characterized in that, described reaction solvent is low-carbon saturated alkane, is normal hexane, hexanaphthene, normal heptane, petroleum One or more mixtures of ether, No. 6 solvent oil, No. 120 solvent oil, and No. 180 solvent oil. 5. The method for preparing a catalyst capable of regulating the molecular weight of polyethylene oxide according to claim 1, wherein the low temperature condition is between -80°C and -10°C, and the ammonia-calcium complex solution reacts to generate ammonia The time for the calcium complex solution is 0.5h to 4h, and the reaction time after adding the modifying agent is 0.5h to 4h. 6. The method for preparing a catalyst capable of regulating the molecular weight of polyethylene oxide according to claim 1, wherein the reaction temperature required for the deamination treatment is between -10°C and 30°C, and the aging treatment The temperature is between 40°C and 150°C, and the aging treatment time is between 0.5h and 4h. 7 . The method for preparing a catalyst capable of regulating the molecular weight of polyethylene oxide according to claim 6 , wherein the aging temperature is in the range of 40° C. to 100° C. 8. the preparation method of the catalyzer of adjustable polyoxyethylene molecular weight according to claim 1 is characterized in that, in the whole process of catalyzer synthesis, reaction system is under the protection of inert gas all the time, carries out strictly in anhydrous and oxygen-free environment . 9. the preparation method of the catalyzer that can control polyoxyethylene molecular weight according to claim 1, is characterized in that, described catalyzer is white particle in the polyoxyethylene prepared by catalytic ethylene oxide ring-opening polymerization, can be in The molecular weight of polyethylene oxide can be adjusted within a wide range, especially suitable for the synthesis of low molecular weight PEO, and the viscosity-average molecular weight of the obtained polyethylene oxide is between 100,000 and 2 million. 10. A catalyst capable of regulating the molecular weight of polyethylene oxide, characterized in that the catalyst is prepared by the method of claim 1.