Polyethyleneimine modified lignin demulsifier as well as preparation method and application thereof

Abstract

The invention discloses a polyethyleneimine modified lignin demulsifier which takes lignin and derivatives thereof as a matrix, and the surface of the matrix is sequentially subjected to epoxy group functionalization and polyethyleneimine modification. The lignin containing a large number of benzene rings is sequentially subjected to epoxy group and polyethyleneimine grafting modification, the wettability of the lignin can be effectively improved, the lignin has excellent interfacial activity, the demulsification temperature is effectively reduced, and the demulsification efficiency is effectively improved; the polyethyleneimine modified lignin demulsifier has the advantages of low demulsifying temperature, less agent dosage, short demulsifying time, high demulsifying efficiency, no toxic or side effect, easiness in degradation, wide applicability, environmental friendliness and the like; the preparation method is simple, mild in reaction condition and suitable for popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemicals, and particularly relates to a polyethyleneimine modified lignin demulsifier, a preparation method and an application thereof. Background Art

[0002] The extraction process of crude oil is usually accompanied by a large amount of formation water, which eventually exists in the form of an emulsion. The most common emulsion is water-in-oil, which is extremely detrimental to oil industry production. Natural active components in crude oil, such as asphaltenes, colloids, crystalline waxes, and clay particles, are adsorbed at the oil-water interface and form a strong viscoelastic interfacial film. The presence of this film inhibits or delays the coalescence of emulsified water droplets and makes it difficult to separate them from the emulsion. Due to the stability of water-in-oil emulsions, they can exist for minutes to years. Therefore, it is essential to dehydrate and separate water-in-oil emulsions through reliable and efficient demulsification technology.

[0003] The demulsification methods of oil-in-water emulsions are generally divided into three types: physical, biological and chemical. Chemical demulsification is widely used because of its advantages such as rapidity, high efficiency and low cost. The key to chemical demulsification is to add a demulsifier to the oil-in-water emulsion. Existing chemical demulsifiers mainly include polymer surfactants, nanoparticles and ionic liquids, such as ethylene oxide-propylene oxide (EO-PO) block copolymers, silicone polyethers, dendrimers, biodegradable polymer surfactants and nanoparticle-based demulsifiers. However, these demulsifiers have many problems, such as complex preparation process, low demulsification efficiency, high demulsification temperature, long demulsification time, non-renewable petrochemical raw materials, high cost, and potential pollution risks to the environment. Seeking new demulsifiers with excellent demulsification performance and low cost remains a huge challenge in the future. Summary of the Invention

[0004] The main purpose of the present invention is to provide a polyethyleneimine modified lignin demulsifier to address the problems and shortcomings of the existing technology, so as to solve the technical difficulties of the existing technology such as complex demulsifier preparation process, low demulsification efficiency, long demulsification time, high demulsification temperature, high raw material cost, and potential pollution risk to the environment.

[0005] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0006] A polyethyleneimine-modified lignin demulsifier is obtained by taking lignin and its derivatives as a matrix and sequentially performing epoxy functionalization and polyethyleneimine modification on the surface.

[0007] In the above scheme, the epoxy functionalization step includes: adding lignin to an alkaline solution, adding a phase transfer catalyst, ultrasonically dispersing, and adding an epoxidation reagent to carry out a grafting reaction to obtain epoxy functionalized lignin.

[0008] In the above scheme, the epoxidation reagent can be selected from one or more substances having both halogen elements and epoxy groups, such as epichlorohydrin, epibromohydrin, and epibromobutyl.

[0009] In the above scheme, the polyethyleneimine modification step includes: adding epoxy functionalized lignin into an organic solvent and dispersing it evenly, adding polyethyleneimine, and performing a ring-opening reaction to obtain the polyethyleneimine-modified lignin demulsifier.

[0010] In the above solution, the molecular weight of the polyethyleneimine is 300-10000.

[0011] Preferably, the molecular weight of the polyethyleneimine is 300-1800.

[0012] In the above scheme, the lignin and its derivatives are one or more of lignin, sodium lignin sulfonate, calcium lignin sulfonate, etc.

[0013] The preparation method of the polyethyleneimine modified lignin demulsifier comprises the following steps:

[0014] 1) Epoxy functionalization;

[0015] Lignin is added to an alkaline solution, a phase transfer catalyst is added, ultrasonic dispersion is performed, an epoxidation reagent is added for grafting reaction, and epoxy groups are grafted onto the lignin through a Williamson etherification reaction to obtain epoxy-functionalized lignin;

[0016] 2) Polyethyleneimine modification;

[0017] The epoxy functionalized lignin is added to an organic solvent and dispersed uniformly, polyethyleneimine is added to carry out a ring-opening reaction, and the polyethyleneimine is grafted onto the lignin by utilizing the ring-opening reaction between the amino group and the epoxy group to obtain the polyethyleneimine modified lignin demulsifier.

[0018] In the above scheme, the alkali solution is one or more of sodium hydroxide solution, potassium hydroxide solution, and potassium carbonate solution; and the concentration is 20-50 wt%.

[0019] In the above scheme, the phase transfer catalyst can be selected from one or more of benzyltriethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, etc., and its usage is 0.1-5% of the total mass of the reactants (lignin and epoxidation reagent).

[0020] In the above scheme, the mass ratio of the lignin and its derivatives, the alkali solution, and the epoxidation reagent is 1:(5-10):(5-10).

[0021] In the above solution, the organic solvent can be selected from one or more aprotic solvents such as tetrahydrofuran, dioxane, acetone, etc.

[0022] In the above scheme, the mass ratio of the epoxy functionalized lignin to the organic solvent is 1:(10-20).

[0023] Preferably, the mass ratio of the epoxy functionalized lignin to polyethyleneimine is 1:(2-5).

[0024] In the above scheme, the grafting reaction temperature in step 1) is 50-100° C. and the time is 10-24 hours; the ring-opening reaction temperature in step 2) is 50-100° C. and the time is 10-24 hours.

[0025] Application of the polyethyleneimine modified lignin demulsifier in demulsification of crude oil emulsion.

[0026] In the above solution, the crude oil emulsion is a water-in-oil type crude oil emulsion.

[0027] In the above solution, the application temperature of the polyethyleneimine modified lignin demulsifier is 50-70°C.

[0028] In the above solution, the pH value of the crude oil emulsion is 2-12, preferably 4-10.

[0029] In the above solution, the salinity of the crude oil emulsion is 0-50000 mg / L.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The polyethyleneimine-modified lignin demulsifier of the present invention is a demulsifier that effectively improves the wettability of lignin by sequentially grafting epoxy groups and polyethyleneimine onto lignin containing a large number of benzene rings, thereby imparting excellent interfacial activity. Lignin can undergo π-π interactions with natural surfactants such as colloids and asphaltene in crude oil, causing it to adsorb at the oil-water interface and replace the colloids and asphaltene, thereby reducing the stability of the interfacial film and inducing demulsification. In addition, the grafted polyethyleneimine can also promote its penetration through the interfacial film, reducing the oil-water interfacial tension and weakening the interfacial film strength. Grafting polyethyleneimine can improve the dispersibility and interfacial activity of the demulsifier in the oil phase, facilitate the diffusion and adsorption of the demulsifier, further reduce the demulsification temperature, and enhance the demulsification efficiency.

[0032] 2) The polyethyleneimine modified lignin demulsifier of the present invention has a low demulsification temperature, a small amount of agent, a short demulsification time, a high demulsification efficiency, no toxic side effects, is easy to degrade, and has no pollution to the environment; it is particularly suitable for environments such as strong acids, strong bases, and high salts, and has a wide range of applications;

[0033] 3) The preparation method of the demulsifier of the present invention is relatively simple, the reaction conditions are mild, and it is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of the polyethyleneimine modified lignin demulsifier prepared in Example 1. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] Example 1

[0037] A polyethyleneimine modified lignin demulsifier, the preparation method of which comprises the following steps:

[0038] 1) 2 g of sodium lignin sulfonate was added to 10 g of a 50 wt% NaOH solution, followed by the addition of 0.02 g of tetrabutylammonium bromide. After ultrasonic dispersion, 10 g of epichlorohydrin was added dropwise. After the addition was complete, the mixture was reacted at 70° C. for 20 h, and then distilled under reduced pressure. The product was then washed with alcohol and dried to obtain epoxy-functionalized lignin.

[0039] 2) 2 g of epoxy-functionalized lignin was added to 30 ml of tetrahydrofuran, and after uniform dispersion, 6 g of polyethyleneimine with a molecular weight of 600 was added. The mixture was reacted at 70° C. for 10 h. After the solvent was removed by vacuum distillation, the product was washed with water to remove unreacted polyethyleneimine, thereby obtaining a polyethyleneimine-modified lignin demulsifier.

[0040] Figure 1 This is a schematic structural diagram of the polyethyleneimine modified lignin demulsifier prepared in Example 1.

[0041] Example 2

[0042] A polyethyleneimine modified lignin demulsifier, the preparation method of which comprises the following steps:

[0043] 1) 2 g of sodium lignin sulfonate was added to 15 g of a 30 wt% NaOH solution, followed by the addition of 0.02 g of tetrabutylammonium bromide. After ultrasonic dispersion, 15 g of epibromopropane was added dropwise. After the addition was complete, the mixture was reacted at 80° C. for 20 h, and then distilled under reduced pressure. The product was then washed with alcohol and dried to obtain epoxy-functionalized lignin.

[0044] 2) 2 g of epoxy-functionalized lignin was added to 30 ml of tetrahydrofuran, and after uniform dispersion, 8 g of polyethyleneimine with a molecular weight of 300 was added. The mixture was reacted at 70° C. for 10 h. After the solvent was removed by vacuum distillation, the product was washed with water to remove unreacted polyethyleneimine, thereby obtaining a polyethyleneimine-modified lignin demulsifier.

[0045] Example 3

[0046] A polyethyleneimine modified lignin demulsifier, the preparation method of which comprises the following steps:

[0047] 1) 2 g of sodium lignin sulfonate was added to 10 g of a 50 wt% NaOH solution, followed by the addition of 0.02 g of tetrabutylammonium chloride. After ultrasonic dispersion, 20 g of epichlorohydrin was added dropwise. After the addition was complete, the mixture was reacted at 70° C. for 20 h, and then distilled under reduced pressure. The product was then washed with alcohol and dried to obtain epoxy-functionalized lignin.

[0048] 2) 2 g of epoxy-functionalized lignin was added to 30 ml of tetrahydrofuran, and after uniform dispersion, 6 g of polyethyleneimine with a molecular weight of 1800 was added. The mixture was reacted at 70° C. for 10 h. After the solvent was removed by vacuum distillation, the product was washed with water to remove unreacted polyethyleneimine, thereby obtaining a polyethyleneimine-modified lignin demulsifier.

[0049] Example 4

[0050] A polyethyleneimine modified lignin demulsifier, the preparation method of which comprises the following steps:

[0051] 1) 2 g of sodium lignin sulfonate was added to 10 g of a 50 wt% NaOH solution, followed by the addition of 0.02 g of tetrabutylammonium chloride. After ultrasonic dispersion, 20 g of epichlorohydrin was added dropwise. After the addition was complete, the mixture was reacted at 70° C. for 20 h, and then distilled under reduced pressure. The product was then washed with alcohol and dried to obtain epoxy-functionalized lignin.

[0052] 2) 2 g of epoxy-functionalized lignin was added to 30 ml of tetrahydrofuran, and after uniform dispersion, 6 g of polyethyleneimine with a molecular weight of 10,000 was added. The mixture was reacted at 70° C. for 10 h. After the solvent was removed by vacuum distillation, the product was washed with water to remove unreacted polyethyleneimine, thereby obtaining a polyethyleneimine-modified lignin demulsifier.

[0053] Comparative Example 1

[0054] A lignin demulsifier, the preparation method of which comprises the following steps:

[0055] 1) 2 g of sodium lignin sulfonate was added to 10 g of a 50 wt% NaOH solution, followed by the addition of 0.02 g of tetrabutylammonium chloride. After ultrasonic dispersion, 20 g of epoxy bromobutane was added dropwise. After the addition was complete, the mixture was reacted at 70° C. for 20 h, and then distilled under reduced pressure. The product was then washed with alcohol and dried to obtain epoxy-functionalized lignin.

[0056] Comparative Example 2

[0057] A polyethyleneimine demulsifier is provided, wherein polyethyleneimine with a molecular weight of 1800 is directly used as the demulsifier.

[0058] Comparative Example 3

[0059] A polyethyleneimine modified cellulose demulsifier, the preparation method of which comprises the following steps:

[0060] 1) adding 2 g of microcrystalline cellulose to 10 g of a 50 wt% NaOH solution, then adding 0.02 g of tetrabutylammonium bromide, and ultrasonically dispersing the mixture. Then, adding 10 g of epichlorohydrin dropwise, reacting at 70° C. for 20 h, and distilling under reduced pressure. The product was then washed with alcohol and dried to obtain epoxy-functionalized microcrystalline cellulose;

[0061] 2) 2 g of epoxy-functionalized microcrystalline cellulose was added to 30 ml of tetrahydrofuran, and after uniform dispersion, 6 g of polyethyleneimine with a molecular weight of 600 was added. The mixture was reacted at 70° C. for 10 h. After the solvent was removed by vacuum distillation, the product was washed with water to remove unreacted polyethyleneimine, thereby obtaining a polyethyleneimine-modified microcrystalline cellulose demulsifier.

[0062] Application Example 1

[0063] The demulsifiers obtained in Examples 1-4 and Comparative Examples 1-3 were applied to crude oil emulsion demulsification, and the specific steps included:

[0064] 1) 150 parts by weight of crude oil was added to 350 parts by weight of deionized water, stirred, heated to 60° C., and then stirred at 11,000 rpm for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0065] 2) A certain amount of the demulsifiers provided in Examples 1-4 and Comparative Examples 1-3 was added to 20 parts by weight of water to prepare a demulsifier solution with a mass fraction of 0.3%, corresponding to Experimental Groups 1-7;

[0066] 3) 1 part by volume of the obtained demulsifier solution was added to 20 parts by volume of the above water-in-oil emulsion, shaken thoroughly to mix evenly, and allowed to stand at 50° C. for 2 h. The dehydration rate was then measured. The results are shown in Table 1.

[0067] Table 1

[0068] Group Demulsifier dosage (mg / L) Demulsification efficiency (%) Experimental Group 1 150 95.1 Experimental Group 2 150 92.6 Experimental Group 3 150 88.7 Experimental Group 4 150 75.1 Experimental Group 5 150 0 Experimental Group 6 150 0 Experimental Group 7 150 10.5

[0069] As shown in Table 1, the polyethyleneimine-modified lignin demulsifiers prepared in Examples 1-3 all have very good demulsification performance, but the demulsification efficiency varies depending on the preparation conditions. The lignin demulsifier prepared in Comparative Example 1 has low interfacial activity and cannot interact with natural interfacial active substances to destroy the interfacial film. The pure polyethyleneimine in Comparative Example 2 also has no demulsification performance. The demulsifier obtained in Comparative Example 3 has poor amphiphilicity and interfacial activity, and low demulsification efficiency.

[0070] Application Example 2

[0071] The polyethyleneimine modified lignin demulsifier provided in Example 1 was used to characterize the application effect of crude oil emulsion demulsification at different concentrations. The specific steps included:

[0072] 1) 150 parts by weight of crude oil was added to 350 parts by weight of deionized water, stirred, heated to 60° C., and then stirred at 11,000 rpm for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0073] 2) Different weight portions of the polyethyleneimine-modified lignin demulsifier prepared in Example 1 were added to water to prepare polyethyleneimine-modified lignin demulsifier solutions with mass fractions of 0.5%, 0.4%, 0.3%, 0.2%, and 0.1%, respectively. The obtained samples were recorded as experimental groups 5-9; the blank group was 0%, and the sample was recorded as experimental group 10;

[0074] 3) 1 part by volume of each of the experimental groups 5-10 was added to 20 parts by volume of the crude oil emulsion and then thoroughly shaken to mix. The mixture was then transferred to a 50°C water bath and allowed to stand for 2 hours. The dehydration rate was measured. The results are shown in Table 2.

[0075] Table 2

[0076] Group Demulsifier dosage (mg / L) Demulsification efficiency (%) Experimental Group 5 250 95.3 Experimental Group 6 200 95.3 Experimental Group 7 150 95.1 Experimental Group 8 100 87.1 Experimental Group 9 50 72.9 Experimental group 10 0 0

[0077] As shown in Table 2, the polyethyleneimine modified lignin demulsifier provided by the present invention has good demulsification performance, and can achieve a demulsification efficiency of 95.1% at a concentration of 150 mg / L.

[0078] Application Example 3

[0079] The polyethyleneimine modified lignin demulsifier provided in Example 1 was used to characterize the demulsification performance at different temperatures and times. The specific steps included:

[0080] 1) 150 parts by weight of crude oil was added to 350 parts by weight of deionized water, stirred, heated to 60° C., and then stirred at 11,000 rpm for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained.

[0081] 2) A certain amount of the demulsifier provided in Example 1 was added to 20 parts by weight of water to prepare a demulsifier solution with a mass fraction of 0.3%, which was recorded as experimental groups 11-14;

[0082] 3) 1 part by volume of the above experimental groups 11-14 was added to 20 parts by volume of the crude oil emulsion and then thoroughly shaken to mix. The mixture was then transferred to a water bath at a set temperature and allowed to stand for 2 hours. The dehydration rate was measured. The results are shown in Table 3.

[0083] Table 3

[0084]

[0085] As shown in Table 3, the polyethyleneimine modified lignin demulsifier provided by the present invention can achieve a demulsification efficiency of 95.1% at 50°C for 1 hour, 97.9% at 60°C for 60 minutes, and 98.5% at 70°C for 30 minutes.

[0086] Application Example 4

[0087] The polyethyleneimine modified lignin demulsifier provided in Example 1 was used to characterize the demulsification performance under different pH conditions. The specific steps included:

[0088] 1) adding 150 parts by weight of crude oil to 350 parts by weight of deionized water, stirring and mixing, heating to 60° C., adjusting the pH by adding hydrochloric acid or sodium hydroxide, and then stirring at 11,000 rpm for 20 minutes. Repeat this process three times until a stable water-in-oil emulsion is obtained;

[0089] 2) A certain amount of the demulsifier provided in Example 1 was added to 20 parts by weight of water to prepare a demulsifier solution with a mass fraction of 0.3%, which was recorded as experimental groups 15-19;

[0090] 3) 1 part by volume of the above experimental groups 15-19 was added to 20 parts by volume of the crude oil emulsion and then thoroughly shaken to mix. The mixture was then transferred to a 50°C water bath and allowed to stand for 2 hours. The dehydration rate was measured. The results are shown in Table 4.

[0091] Table 4

[0092] Group pH Demulsification efficiency (%) Experimental group 15 4 96.3 Experimental group 16 6 95.8 Experimental group 17 7 95.1 Experimental group 18 8 92.6 Experimental Group 19 10 90.5

[0093] As shown in Table 4, the polyethyleneimine modified lignin demulsifier provided by the present invention still has a high demulsification efficiency within the pH range of strong acid and strong base.

[0094] Application Example 5

[0095] The polyethyleneimine modified lignin demulsifier provided in Example 1 was used to characterize the demulsification performance under different salinity conditions. The specific steps included:

[0096] 1) 150 parts by weight of crude oil was added to 350 parts by weight of deionized water, stirred and mixed, heated to 60° C., salinity was adjusted by adding sodium chloride, and then stirred at 11,000 rpm for 20 minutes. This process was repeated three times until a stable water-in-oil emulsion was obtained;

[0097] 2) A certain amount of the demulsifier provided in Example 1 was added to 20 parts by weight of water to prepare a demulsifier solution with a mass fraction of 0.3%, which was recorded as experimental groups 20-25;

[0098] 3) 1 part by volume of the experimental groups 20-25 was added to 20 parts by volume of the crude oil emulsion and thoroughly shaken to mix. The mixture was then transferred to a 50°C water bath and allowed to stand for 2 hours. The dehydration rate was measured. The results are shown in Table 5.

[0099] Table 5

[0100]

[0101]

[0102] It can be seen from Table 5 that the polyethyleneimine modified lignin demulsifier provided by the present invention can have a stable demulsification efficiency under high salinity conditions, indicating that the demulsifier has high salt resistance.

[0103] The demulsifier provided by the present invention has the advantages of small dosage, low demulsification temperature, short demulsification time, high demulsification efficiency, no toxic side effects, easy degradation, no pollution to the environment, etc., and is suitable for a wide pH range and has high salt tolerance.

[0104] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A polyethyleneimine modified lignin demulsifier, characterized in that, The composite material is obtained by using lignin and its derivatives as the matrix, and sequentially performing epoxy functionalization and polyethyleneimine modification on the surface.

2. The polyethyleneimine modified lignin demulsifier according to claim 1, characterized in that The epoxy functionalization step comprises: adding lignin into an alkaline solution, adding a phase transfer catalyst, ultrasonically dispersing, and adding an epoxidation reagent to carry out a grafting reaction to obtain epoxy functionalized lignin.

3. The polyethyleneimine modified lignin demulsifier according to claim 2, characterized in that The epoxidation reagent contains both halogen elements and epoxy groups.

4. The polyethyleneimine modified lignin demulsifier according to claim 1, characterized in that The polyethyleneimine modification step comprises: adding epoxy functionalized lignin into an organic solvent and dispersing the mixture uniformly, adding polyethyleneimine, and performing a ring-opening reaction to obtain the polyethyleneimine modified lignin demulsifier.

5. The polyethyleneimine modified lignin demulsifier according to claim 4, characterized in that The molecular weight of the polyethyleneimine is 300-10000.

6. The polyethyleneimine modified lignin demulsifier according to claim 1, characterized in that The lignin and its derivatives are one or more of lignin, sodium lignin sulfonate and calcium lignin sulfonate.

7. The method for preparing the polyethyleneimine modified lignin demulsifier according to any one of claims 1 to 6, characterized in that: The steps include: 1) Epoxy functionalization; The lignin is added to an alkaline solution, a phase transfer catalyst is added, ultrasonic dispersion is performed, and an epoxidation reagent is added to carry out a grafting reaction to obtain epoxy-functionalized lignin; 2) Polyethyleneimine modification; The epoxy functionalized lignin is added into an organic solvent and dispersed uniformly, and polyethyleneimine is added to carry out a ring-opening reaction to obtain the polyethyleneimine modified lignin demulsifier.

8. The preparation method according to claim 7, characterized in that The mass ratio of the lignin and its derivatives, the alkali solution and the epoxidation reagent is 1:(5-10):(5-10).

9. The preparation method according to claim 7, characterized in that The mass ratio of the epoxy functionalized lignin to polyethyleneimine is 1:(2-5).

10. Application of a polyethyleneimine modified lignin demulsifier in demulsifying crude oil emulsion.

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