CN101544735B - Three-element comb type copolymer, preparation method and application thereof - Google Patents

Abstract

The present invention relates to a kind of ternary comb copolymer and its preparation method and application. The preparation process is divided into two steps: firstly, utilize the method of free radical polymerization to make α-olefin and maleic anhydride monomer copolymerize, through in the polymerization process Add styrene monomer to obtain terpolymer of α-olefin, maleic anhydride and styrene; then, add primary alcohol or primary amine to react with acid anhydride to obtain non-polar alkyl side chain, It is also a ternary comb copolymer containing polar carboxylic acid and aromatic groups. The degree of hydrophobicity, Polarity and the content of aromatic groups in the copolymer. Experimental results show that after adding the ternary comb copolymer of the present invention to various crude oils, the yield stress of these crude oils at low temperatures is significantly reduced, and the wax crystal size becomes smaller, and the effect of pour point and viscosity reduction is obvious.

Description

A kind of ternary comb copolymer and its preparation method and application

technical field

The invention relates to a polymer and its preparation method and application, in particular to preparing a ternary comb copolymer by free radical solution polymerization and applying it to pipeline transportation of crude oil and deep sea oil recovery.

Background technique

More than 80% of the crude oil produced in my country is waxy crude oil, and there is also a considerable amount of waxy crude oil in the crude oil produced by various countries in the world. Waxy crude oil has a high freezing point and complex rheology (the flow characteristics of non-Newtonian fluids such as thixotropy, yield stress, viscoelasticity, and dependence on shear history and thermal history at room temperature and pressure), which give rise to crude oil production, Storage and transportation have brought many problems and difficulties, such as high energy consumption for oil transportation and potential safety hazards in pipeline operation. Especially in the winter in the north and the oil pipelines laid on the seabed, the temperature is too low, the wax group in the crude oil is analyzed and deposited, causing frequent pipeline blockages, which brings serious troubles to oil transportation. Since the water temperature in the deep sea is often only about 4°C, this problem is even more serious during subsea oil production and transportation.

At home and abroad, physical and chemical methods are often used to deal with the problem of solid deposition pipe plugging during low-temperature transportation of high-wax crude oil. Physical methods are mainly heating along the way and mechanical pigging. The former consumes a lot of energy, while the latter requires high investment in technical equipment. The chemical method is to change the crystalline form of wax in crude oil through additives, such as size and shape, so that the wax is not easy to form a cross-linked three-dimensional space network structure at low temperature, so as to achieve the purpose of depressing the point point and improving the low-temperature fluidity of crude oil. This method has the advantages of simple operation, less investment in equipment, and does not require post-treatment of crude oil, and has been widely used at home and abroad.

There are many types of pour point depressants for crude oil. Based on the research on pour point depressants at home and abroad since 1931, the pour point depressants with better effect on crude oil pour point depressants mainly include the following two types: (1) EVA and its modified products . Mainly use the third monomer to modify EVA by grafting or copolymerization, such as styrene and acrylate, but the disadvantage is that the overall effect needs to be improved, and it needs to be used in conjunction with other types of pour point depressants; (2) poly(formazine) base) acrylate series. There are mainly C18-22 alkyl poly(meth)acrylates, complexes of C14-22 alkyl (meth)acrylate-olefin copolymers, and copolymers of (meth)acrylates and other monomers. Its disadvantage is that the effect is relatively single, and it usually needs to be used in combination. In addition, there have been some reports about maleic anhydride copolymer pour point depressants in recent years, but the ternary comb copolymer designed and synthesized by the present invention is different from all previous reports.

Due to the difference in origin, the composition of various crude oils varies greatly. However, most polymer pour point depressants currently available on the market are limited to interact with a single component in crude oil due to their relatively single chemical structure, so there are still many defects in terms of versatility. The present invention realizes the introduction of non-polar long chains, polar groups and aromatic groups in the polymer chain segment through the free radical copolymerization method, and these groups are driven by hydrophobic association and polar group coupling. The assembly of crude oil interacts with the non-polar wax components in crude oil and the polar components and aromatic components in asphaltenes and colloids, thereby effectively preventing the fusion of wax crystals and the agglomeration of asphaltene and colloids. To a certain extent, the versatility of the polymer pour point depressant is improved.

Contents of the invention

The purpose of the present invention is to overcome the defect of poor versatility of most commercially available pour point depressants, and develop a polymer pour point depressant which is applicable to most crude oils and has strong versatility. After consulting a large number of documents, and based on years of experience in crude oil pour point depressant research, the present invention develops a new method for preparing ternary comb copolymer crude oil low temperature flow modifier by free radical copolymerization.

The process of preparing said ternary comb copolymer is as follows:

Among them, 7<m<24, 0<n<21.

The preparation of this ternary comb copolymer is divided into two steps, as follows:

(1) Terpolymer prepared by free radical solution polymerization

Put 50ml of solvent (xylene), first monomer (maleic anhydride), second monomer (α-olefin) and initiator (such as azobisisobutyronitrile, benzoyl peroxide) into a 250ml three-necked flask middle. The feeding amount of the first monomer is 0.06mol, the feeding amount of the second monomer is equivalent to 100-200mol% of the first monomer, and the feeding amount of the initiator is equivalent to 1-3mol% of the first monomer. After fully dissolving, nitrogen gas was pumped and filled 3 to 5 times, so that the reaction system was placed under strict nitrogen protection. After the temperature rises rapidly to 100-120° C., the polymerization reaction is carried out for 0.5-2 hours. Lower the system temperature to 70-90°C, slowly add the third monomer (styrene), and add a small amount of initiator (such as azobisisobutyronitrile, benzoyl peroxide) and solvent. The addition amount of the third monomer is equivalent to 0-100 mol% of the first monomer, the amount of added initiator is equivalent to 0.1-0.3 mol% of the first monomer, and the dropping rate is controlled at 5-10 drops/minute . Continue to react at 70-90° C. for 4-8 hours to finally obtain a terpolymer of the first monomer, the second monomer and the third monomer.

Due to the influence of the reactivity ratio between the first monomer and the second monomer, the amount of the second monomer should be more than that of the first monomer, otherwise the content of the second monomer in the copolymer will decrease , the number of non-polar long-chain side groups it contains is also correspondingly reduced, which eventually leads to a decrease in the interaction with the non-polar wax components in crude oil, and weakens the pour point depressing effect. In addition, the dosage of the initiator needs to be moderate. If the dosage is too small, the polymerization reaction speed will be slow and the polymerization time will be long; if the dosage is too high, the molecular weight of the copolymer will decrease and the molecular weight distribution will widen. In view of the fact that the copolymerization reaction of the first monomer and the second monomer has consumed most of the initiator, a small amount of initiator needs to be added when adding the third monomer. In addition, it should be noted that since the reactivity ratio between the third monomer and the first monomer is higher than that of the second monomer, the feeding time of the third monomer should not be too early, and the dropping rate should not be too fast, otherwise it is easy to get the third monomer. Alternating copolymers of monomers and first monomers or homopolymers by themselves.

(2) Chemical modification (esterification or amination) of terpolymers to prepare ternary comb copolymers

The terpolymer obtained in the first step can be treated and purified to take out the second step reaction, or directly carry out the second step reaction. Add the first modifier (any one of dodecyl alcohol to stearyl alcohol) or the second modifier (any one of dodecylamine to octadecylamine) into the reaction system, and the amount of feed is equivalent to the first 100-200mol% of the monomer. React at 100-120°C for 8-15 hours to finally obtain a chemically modified (esterified or aminated) ternary copolymer, that is, a ternary comb-shaped copolymer. The degree of esterification or degree of amination can be controlled by adjusting the feeding amount of the first modifier or the second modifier, so that ternary comb copolymers with different polarities can be obtained.

The chemical structure of the ternary comb copolymer was analyzed by hydrogen nuclear magnetic resonance ( ¹ H NMR), and the degree of esterification or amination of the ternary comb copolymer was calculated by using the spectrum peak integral value of different hydrogen atoms . The degree of esterification or amination here refers to the number of a maleic anhydride group in the polymer that is finally transformed into an ester group or an amide group, and the size is between 0 and 2. Since the chemical shift of the hydrogen atom on the _CH3 at the alkyl end is 0.88ppm, and the chemical shift of the hydrogen circle of the CH group on the maleic anhydride is 3.28ppm, the following formula can be used to calculate the degree of esterification or amination (f) .

$\frac{{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; CH</span>}}}{{\mathrm{<span\; class="notranslate">\; A</span>}}_{{\mathrm{<span\; class="notranslate">\; CH</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; f</span>}}$ $\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{{\mathrm{<span\; class="notranslate">\; CH</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}}{{\mathrm{<span\; class="notranslate">\; 3</span>}\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; CH</span>}}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}$

The range of the degree of esterification or amination calculated by this formula is between 1.0 and 1.3, which means that about every two maleic anhydride groups have an esterification or amination reaction, forming an ester group (or amide group) and a carboxylic acid group.

In addition, the molecular weight of the ternary comb copolymer was tested by gel permeation chromatography (GPC), and the molecular weight of the ternary comb copolymer ranged from 5000 to 20000 g/mol.

Add ternary comb copolymers to different crude oils, such as crude oils from Changqing Oilfield and Shengli Oilfield, use rheometer to test their yield stress changes at low temperatures before and after adding, and find that after adding 0.05-0.5wt% ternary After the comb copolymer, the yield stress of various crude oils is significantly reduced, generally by one order of magnitude, and up to four orders of magnitude. The morphology and distribution of their wax crystals at low temperature were observed with a polarizing microscope, and it was found that the size of the wax crystals was significantly smaller, the dispersion increased, and the low-temperature fluidity of crude oil was significantly improved. Its mechanism of action is: non-polar alkyl side chains self-assemble into nuclei or produce eutectics with wax components in crude oil, polar groups interact with asphaltenes and polar components in colloids to form micelles, and The benzene ring in the polystyrene unit interacts with the aromatic components in crude oil, thereby preventing the fusion of wax crystals in crude oil and the agglomeration of asphaltenes and colloids.

Description of drawings

Fig. 1 is a comparison chart of yield stress of crude oil before and after adding ternary comb copolymer (0°C);

Fig. 2 is a polarized light microscope photograph (0° C.) of crude oil (part a) and crude oil (part b) after adding 0.05 wt % ternary comb copolymer.

Detailed ways

Below, further illustrate the present invention with embodiment, but protection scope of the present invention is not limited to embodiment. Other changes and modifications made by those skilled in the art without departing from the spirit and protection scope of the present invention are still included in the protection scope of the present invention.

Embodiment 1 free radical solution polymerization prepares ternary comb copolymer

Put 50ml of o-xylene, 5.96g of maleic anhydride, 21.56g of octadecene and 0.25g of benzoyl peroxide into a 250ml three-necked flask. Pump nitrogen 3 to 5 times, after fully dissolving, react at 110°C for 1 hour. After the temperature dropped to 75°C, 3.12g of styrene, 0.03g of benzoyl peroxide and 15ml of o-xylene were slowly dropped into the reaction system, and the reaction was continued at 75°C for 8 hours to obtain a terpolymer. Finally, 14.84 g of dodecylamine was added and reacted at 110° C. for 15 hours to complete the amination reaction, and finally a ternary comb copolymer was obtained.

Embodiment 2 free radical solution polymerization prepares ternary comb copolymer

Put 50ml o-xylene, 5.96g maleic anhydride, 19.60g tetradecene and 0.20g benzoyl peroxide into a 250ml three-necked flask. Pump nitrogen 3 to 5 times, fully dissolve, and react at 120°C for 1 hour. After the temperature dropped to 85°C, 4.16g of styrene, 0.02g of benzoyl peroxide and 15ml of o-xylene were slowly dropped into the reaction system, and the reaction was continued at 85°C for 6 hours to obtain a terpolymer. Finally, 21.56 g of octadecylamine was added and reacted at 120° C. for 8 hours to complete the amination reaction, and finally a ternary comb copolymer was obtained.

Embodiment 3 free radical solution polymerization prepares ternary comb copolymer

Put 50ml o-xylene, 5.96g maleic anhydride, 11.76 dodecene and 0.25g benzoyl peroxide into a 250ml three-neck flask. Pump nitrogen 3 to 5 times, fully dissolve, and react at 100°C for 2 hours. After the temperature dropped to 75°C, 4.16g of styrene, 0.02g of benzoyl peroxide and 15ml of o-xylene were slowly dropped into the reaction system, and the reaction was continued at 75°C for 8 hours to obtain a terpolymer. Finally, 26.57 g of hexadecylamine was added, and the amination reaction was completed at 100° C. for 24 hours to obtain a ternary comb copolymer.

Claims (3)

1. the preparation method of a three-element comb type copolymer is characterized in that, comprises the steps:

(1) free radical solution polymerization prepares terpolymer:

Add first monomer, second monomer, initiator and solvent in reactor, stirring is fully dissolved it, reacts 0.5～2 hour under nitrogen protection and 100～120 ℃ of conditions; System temperature is reduced to 70～90 ℃, slowly adds the 3rd monomer then, and add a small amount of initiator and solvent, rate of addition is controlled at 5～10 droplets/minute; Continuation finally can obtain terpolymer 70～90 ℃ of reactions 4～8 hours;

Wherein, the consumption mol ratio is first monomer: second monomer: the 3rd monomer: initiator=1: 1～2: 0～1: 0.01～0.03, and the amount of adding initiator is equivalent to described first monomeric 0.1～0.3mol%;

(2) the chemically modified terpolymer prepares three-element comb type copolymer:

With the reaction system of first properties-correcting agent or second properties-correcting agent adding step (1), reacted 8～24 hours down at 100～120 ℃, obtain esterification or aminating terpolymer at last, i.e. three-element comb type copolymer;

Wherein, the consumption of first properties-correcting agent or second properties-correcting agent is equivalent to described first monomeric 100～200mol%;

Described initiator is benzoyl peroxide or Diisopropyl azodicarboxylate, and described solvent is p-Xylol or o-Xylol, and described first monomer is a maleic anhydride, described second monomer is an alpha-olefin, described the 3rd monomer is a vinylbenzene, and described first properties-correcting agent is primary alconol, and described second properties-correcting agent is primary amine;

Described alpha-olefin can be any in laurylene～octadecylene, and used primary alconol or primary amine can be any in lauryl alcohol～stearyl alcohol or the amino dodecane～stearylamine; The molecular weight of described three-element comb type copolymer is 5000～15000, and the gamma value of described terpolymer esterification or aminate or amination degree are 1.0～1.3.

2. the three-element comb type copolymer that obtains of the preparation method of claim 1.

3. the application of the three-element comb type copolymer of claim 2 is characterized in that, recovers the oil in the pipeline transportation or the deep-sea that are used for crude oil.

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