Lignin-based polyether, lignin-based composite emulsifier and preparation method and application thereof

Abstract

The invention discloses lignin-based polyether, a lignin-based composite emulsifier and a preparation method and application of the lignin-based polyether and the lignin-based composite emulsifier. The lignin-based composite emulsifier comprises a modified lignin surfactant A and a modified lignin surfactant B. The modified lignin surfactant A is prepared by degrading lignin to improve activity and then modifying by alkoxy to obtain lignin-based polyether; the modified lignin surfactant B is prepared by degrading lignin to improve the activity and then modifying by long-chain alkyl to obtain hydrophobically modified lignin. The lignin-based composite emulsifier can be applied to the inverse emulsion synthesis process of acrylamide polymers, and can well emulsify and stabilize a polymerization reaction system. The emulsification system expands the raw material source of the surfactant, all the surfactants belong to natural surfactants, are high in safety and biodegradable, and after the acrylamide polymer is injected underground, the phenylpropane structure of the lignin can well emulsify crude oil, so that the emulsification and extraction of the crude oil are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of emulsifiers for synthesizing acrylamide polymers by inverse emulsion polymerization. Further, it relates to lignin-based polyethers, lignin-based composite emulsifiers, and their preparation methods and applications. Background Art

[0002] As clay stabilizers, oil displacement agents, fluid loss control agents, thickeners, etc., acrylamide polymers have been widely used in drilling, fracturing, oil displacement, and water plugging, and are extremely important oilfield chemicals. There are mainly two types of acrylamide polymers: powder and emulsion. Among them, the emulsion is prepared by inverse emulsion polymerization, that is, in the aqueous phase dissolved with monomers, it is dispersed into a water-in-oil (W / O) type through an emulsifier for polymerization.

[0003] Emulsifiers belong to surfactants, which are substances that can form micelles and play an important role in emulsion polymerization. The types and amounts of emulsifiers and the selection of the emulsion system directly affect the stability of the inverse emulsion and are necessary conditions for a successful polymerization reaction.

[0004] The reserves of lignin in nature are second only to cellulose, and it is the second largest natural organic matter. Industrial lignin is rich in sources and low in price, and can be used as a raw material for producing oilfield chemicals. With the rising price of petrochemical raw materials and the increasing environmental protection requirements, green chemicals using low-cost natural renewable resources such as lignin as raw materials have become an international hot research and development direction.

[0005] Natural lignin is a natural polyaromatic macromolecular compound composed of hydrophobic non-polar groups with a phenylpropane skeleton and hydrophilic polar groups such as phenolic groups. The main connection methods between the structural main bodies of lignin are ether bonds and carbon-carbon bonds. These two bonds have low molecular polarity and high bond energy and are difficult to react. Moreover, the methoxy content is high, the hydroxyl content is low, and the steric hindrance on the benzene ring is large, resulting in significantly insufficient reaction activity. For commercially available industrial by-product lignin, due to the condensation reaction after chemical treatment, its reaction sites are even fewer. Therefore, although lignin has certain surface activity, due to its poor performance, it is not ideal to be directly used as an emulsifier, and its application market is greatly restricted. However, using lignin as a raw material for preparing emulsifiers can turn waste into treasure and significantly reduce the cost of emulsifiers. Summary of the Invention

[0006] To solve the problems in the prior art, the present invention provides a lignin-based polyether, a lignin-based composite emulsifier, and their preparation methods and applications. The lignin-based composite emulsifier of the present invention is composed of a modified lignin surfactant A and a modified lignin surfactant B. Among them, the modified lignin surfactant A is obtained by first degrading lignin to improve its activity and then subjecting it to alkoxy modification; the modified lignin surfactant B is obtained by first degrading lignin to improve its activity and then subjecting it to long-chain alkyl modification.

[0007] This lignin-based composite emulsifier can be applied to the inverse emulsion synthesis process of acrylamide polymers, and can emulsify and stabilize the polymerization reaction system well. This emulsification system expands the raw material sources of surfactants. They all belong to natural surfactants, with high safety, biodegradability, and after being injected into the ground with acrylamide polymers, the phenylpropane structure of lignin can emulsify crude oil well, which is beneficial to the emulsification and production of crude oil. When the lignin-based composite emulsifier is used in the process of inverse emulsion synthesis of acrylamide polymers, the obtained emulsion products have the characteristics of low gel content, higher molecular weight, better long-term storage stability, lower residual monomer content, and faster dissolution rate. This emulsification system reduces the production cost of acrylamide polymer emulsions, can meet the performance and economic requirements of on-site construction, and has high practicability.

[0008] One of the purposes of the present invention is to provide a lignin-based polyether, which is prepared by reacting raw materials including acid-degraded phenolic-modified lignin and epoxides.

[0009] Another purpose of the present invention is to provide a preparation method of the lignin-based polyether, which includes the following steps:

[0010] Add raw materials including acid-degraded phenolic-modified lignin and epoxides into water and mix. After adjusting the pH, heat and react to obtain the lignin-based polyether;

[0011] Preferably, it is used to prepare the lignin-based polyether described in one of the purposes of the present invention.

[0012] In the preparation method of the lignin-based polyether of the present invention, preferably,

[0013] The epoxide is selected from at least one of ethylene oxide and propylene oxide; and / or,

[0014] Adjust the pH value to 10.5 - 11.5; and / or,

[0015] Based on the total mass of the acid-degraded phenolic-modified lignin, epoxide, and water added in this step being 100%,

[0016] The addition amount of the acid-degraded phenolic-modified lignin is 15 - 30 wt%;

[0017] The addition amount of the epoxy compound is 0.15 - 3 wt%; the balance is water; and / or,

[0018] The temperature of the heating reaction is 50 - 65 °C; and / or,

[0019] The time of the heating reaction is 0.5 - 1.5 h; and / or,

[0020] The pressure of the heating reaction is (-0.1) - (-0.2) MPa; and / or,

[0021] After the heating reaction, the pH value is adjusted to 6.5 - 7.5 before the purification treatment.

[0022] In the present invention, under certain temperature and certain pressure, in an alkaline system, highly active lignin and an epoxy compound are brought into contact reaction for a period of time to obtain lignin-based polyether; after the reaction is completed, the system is cooled to room temperature, the pH is adjusted to neutral, and then separated and purified to obtain lignin-based polyether, denoted as modified lignin surfactant A.

[0023] The third object of the present invention is to provide a lignin-based composite emulsifier, and the lignin-based composite emulsifier comprises modified lignin surfactant A and modified lignin surfactant B;

[0024] The modified lignin surfactant A is selected from the lignin-based polyether described in the first object of the present invention or the lignin-based polyether prepared by the method described in any one of the second objects of the present invention;

[0025] The modified lignin surfactant B is selected from the hydrophobic modified lignin prepared by reacting raw materials including acid-degraded phenolic modified lignin and long-chain acid.

[0026] Both the lignin-based polyether and the hydrophobic modified lignin of the present invention are nonionic surfactants. Compared with conventional petroleum-based small molecule emulsifiers, they have good emulsifying performance, hard water resistance and low foaming property. The two macromolecular modified lignins have synergistic effects to form an emulsifying system with a complex three-dimensional structure, improving the stability and efficiency of the emulsifying system.

[0027] In the lignin-based composite emulsifier of the present invention, preferably,

[0028] In the lignin-based composite emulsifier,

[0029] The content of the modified lignin surfactant A is 10 - 35 wt%;

[0030] The content of the modified lignin surfactant B is 65 - 90 wt%;

[0031] Preferably,

[0032] The content of the modified lignin surfactant A is 20 - 30 wt%.

[0033] The content of the modified lignin surfactant B is 70 - 80 wt%.

[0034] In the lignin-based composite emulsifier of the present invention, preferably,

[0035] The preparation method of the modified lignin surfactant B includes:

[0036] Under the action of an alkylation catalyst, raw materials including acid-degraded phenolic-modified lignin and long-chain acid are heated and reacted in water to obtain hydrophobically modified lignin.

[0037] In the lignin-based composite emulsifier of the present invention, preferably,

[0038] The alkylation catalyst is selected from solid superacids; preferably selected from at least one of SO4 2- / ZrO2, WO3 / ZrO2, and further preferably the ZrO2 content is 80 - 90 wt%; and / or,

[0039] The long-chain acid is selected from long-chain acids of C12 - C18; preferably selected from at least one of oleic acid, stearic acid, palmitic acid, lauric acid; and / or,

[0040] Based on the total mass of the alkylation catalyst, acid-degraded phenolic-modified lignin, long-chain acid, and water added in this step being 100%,

[0041] The addition amount of the alkylation catalyst is 1 - 3 wt%;

[0042] The addition amount of the long-chain acid is 0.5 - 2.5 wt%;

[0043] The addition amount of the acid-degraded phenolic-modified lignin is 15 - 30 wt%; the rest is water; and / or,

[0044] The temperature of the heating reaction is 150 - 200 °C; and / or,

[0045] The time of the heating reaction is 4 - 8 h.

[0046] In the lignin-based composite emulsifier of the present invention, preferably,

[0047] The preparation method of the acid-degraded phenolic-modified lignin is:

[0048] Under closed conditions, after the raw materials including lignin and degradation catalyst are subjected to a contact reaction in water, a phenolic modifier is added and the temperature is further increased for reaction, and then post-treatment is carried out to obtain acid-degraded phenolic-modified lignin;

[0049] Preferably,

[0050] The lignin is selected from at least one of alkali lignin and enzymatically hydrolyzed lignin; and / or,

[0051] The phenolic modifier is selected from at least one of phenol and hydroquinone; and / or,

[0052] The degradation catalyst is a strong acid, preferably selected from at least one of permanganic acid, hydrochloric acid, and sulfuric acid; and / or,

[0053] Based on the total mass of lignin, phenolic modifier, degradation catalyst, and water added in this step being 100%,

[0054] The addition amount of lignin is 15 - 30 wt%;

[0055] The addition amount of the degradation catalyst is 0.005 - 0.02 wt%; and / or,

[0056] The addition amount of the phenolic modifier is 15 - 25 wt%; the balance is water; and / or,

[0057] The temperature of the contact reaction is 65 - 80 °C; and / or,

[0058] The time of the contact reaction is 1.5 - 3 h; and / or,

[0059] The temperature of the continued heating reaction is 95 - 125 °C; and / or,

[0060] The time of the continued heating reaction is 1.5 - 4 h.

[0061] In the present invention, highly active lignin (acid - degraded phenolic - modified lignin) is prepared by the following method: under certain temperature and airtight conditions, lignin is subjected to dynamic contact reaction with a degradation catalyst and a phenolic modifier for a period of time; after the reaction is completed, the system is cooled to room temperature, an organic solvent is added to completely dissolve the mixture, and then water is added to precipitate the modified product, and the highly active lignin is obtained by separation, washing, and drying.

[0062] The fourth object of the present invention is to provide a preparation method of the lignin - based composite emulsifier according to any one of the third objects of the present invention, including the following steps:

[0063] The modified lignin surfactant A and the modified lignin surfactant B are mixed uniformly to obtain the lignin - based composite emulsifier.

[0064] The fifth object of the present invention is to provide an acrylamide - based polymer emulsion, which is prepared by inverse emulsion synthesis using raw materials including the lignin - based composite emulsifier, monomer, initiator, and chelating agent according to any one of the third objects of the present invention to obtain the acrylamide - based polymer emulsion.

[0065] The sixth object of the present invention is to provide a method for preparing an acrylamide polymer emulsion, comprising forming an oil solution from a composite emulsifier and an organic solvent; the composite emulsifier is selected from the lignin-based composite emulsifiers described in any one of the third objects of the present invention;

[0066] Mixing a vinyl monomer, optionally a sulfonic acid monomer, a chelating agent, a partial initiator and water to form an aqueous solution;

[0067] Mixing the oil solution and the aqueous solution to form a water-in-oil emulsion;

[0068] After deoxygenating the water-in-oil emulsion, adding the remaining initiator for a polymerization reaction to obtain an acrylamide polymer emulsion;

[0069] Preferably, the method is used for preparing the acrylamide polymer emulsion described in the fifth object of the present invention.

[0070] In the method for preparing the acrylamide polymer emulsion according to the present invention, preferably,

[0071] the organic solvent is selected from at least one of white oil and kerosene; and / or,

[0072] the mass ratio of the organic solvent to the composite emulsifier is 1:0.05 - 0.2; and / or,

[0073] the vinyl monomer is selected from at least one of acrylamide, acrylic acid, and N-isopropylacrylamide; and / or,

[0074] the sulfonic acid monomer is selected from at least one of 2-acrylamido-2-methylpropanesulfonic acid and 2-acryloyloxy-2-methylpropanesulfonic acid; and / or,

[0075] the chelating agent is selected from at least one of disodium ethylenediaminetetraacetate and trisodium ethylenediaminetetraacetate; and / or,

[0076] the initiator is selected from at least one of redox initiators (such as ammonium persulfate - sodium bisulfite) and azo initiators (such as VA-044); and / or,

[0077] In the aqueous solution,

[0078] the content of the vinyl monomer is 40 - 60 wt%;

[0079] the content of the sulfonic acid monomer is 0 - 50 wt%;

[0080] the content of the chelating agent is 0.01 - 0.1 wt%;

[0081] the content of the partial initiator added is 0.01 - 0.1 wt%; and / or,

[0082] The mass ratio of the partial initiator to the remaining initiator is 1 - 4:1; and / or,

[0083] The mass ratio of the aqueous solution to the oil solution is 1 - 3:1; and / or,

[0084] The temperature of the polymerization reaction does not exceed 40°C; preferably, the temperature of the polymerization reaction does not exceed 35°C; and / or,

[0085] The time of the polymerization reaction is 2 - 6 h.

[0086] In the present invention, for the preparation of the acrylamide polymer emulsion by using the lignin - based composite emulsifier in the reverse - phase emulsion synthesis, specifically: forming an oil solution by mixing the lignin - based composite emulsifier with an organic solvent; forming an aqueous solution by mixing an acrylamide - type monomer, a chelating agent, a partial initiator and water; mixing the oil solution with the aqueous solution to form a water - in - oil emulsion; after deoxidizing the water - in - oil emulsion, adding the remaining initiator to carry out the polymerization reaction of the water - in - oil emulsion.

[0087] The seventh object of the present invention is to provide an application of the acrylamide polymer emulsion prepared by the method as described in any one of the sixth objects of the present invention to the seventh object of the present invention in oil exploitation.

[0088] In the present invention, the lignin, the catalyst and the phenolic modification agent can all be obtained commercially;

[0089] In the present invention, the method for adjusting the pH is a method commonly used in the art. Preferably, the pH is adjusted by adding an acidic substance or a basic substance. The acidic substance can be at least one of hydrochloric acid, sulfuric acid, acetic acid, oxalic acid, etc.; the basic substance is sodium hydroxide, potassium hydroxide, etc.

[0090] In the present invention, the purification method can be a conventional purification method in the art. For example, the mixture solution obtained after the reaction is centrifuged, then washed repeatedly, and finally dried under vacuum.

[0091] In the ranges and any values disclosed in the present invention, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. In the following text, in principle, the various technical solutions can be combined with each other to obtain new technical solutions, which should also be regarded as specifically disclosed herein.

[0092] Compared with the prior art, the present invention has the following advantages:

[0093] The present invention provides a lignin-based composite emulsifier, a preparation method thereof and an application. The lignin-based composite emulsifier in this patent includes a modified lignin surfactant A and a modified lignin surfactant B. Among them, the modified lignin surfactant A is obtained by first degrading lignin to improve its activity and then carrying out alkoxy modification; the modified lignin surfactant B is obtained by first degrading lignin to improve its activity and then carrying out long-chain alkyl modification. The inventors of the present invention unexpectedly found in the research that by carrying out a contact reaction between lignin and a degradation catalyst, not only can the molecular weight of lignin be reduced, the steric hindrance of the reaction be reduced, but also the relative content of active functional groups such as hydroxyl groups in lignin can be increased, greatly improving the reaction activity of lignin; after the degraded lignin contacts with a phenolic modifier, the phenolic hydroxyl group content of lignin can be greatly increased, further improving the conversion rate of lignin in subsequent alkoxy modification and long-chain alkyl modification. When the lignin-based composite emulsifier is used in the process of synthesizing acrylamide polymers by inverse emulsion, the obtained emulsion product has the characteristics of low gel content, higher molecular weight, better long-term storage stability, lower residual monomer content and faster dissolution rate. Detailed implementation manners

[0094] The present invention will be specifically described below in conjunction with specific embodiments. It is necessary to point out here that the following embodiments are only used for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the content of the present invention still fall within the protection scope of the present invention.

[0095] In addition, it should be noted that among the various specific technical features described in the following detailed implementation manners, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0096] In addition, any combination can be made between various different implementation manners of the present invention as long as it does not violate the idea of the present invention. The technical solutions formed thereby belong to a part of the original public content of this specification and also fall within the protection scope of the present invention.

[0097] Source of raw materials:

[0098] Enzymatic hydrolysis lignin is purchased from Shandong Longli Biotechnology Co., Ltd., and the effective lignin content is 94.8 wt%.

[0099] Alkali lignin is purchased from J&K Scientific Ltd.

[0100] The catalyst WO3 / ZrO2 is purchased from Beijing Innochem Science & Technology Co., Ltd.;

[0101] Catalyst SO4 2- / ZrO2 was purchased from Beijing InnoChem Science & Technology Co., Ltd.;

[0102] Other raw materials of the present invention are all conventional commercially available products.

[0103] Testing method:

[0104] Molecular weight test:

[0105] The intrinsic viscosity was determined according to the method for determining the intrinsic viscosity of polyacrylamide in GB 12005.1-1989, and the molecular weight was calculated based on the intrinsic viscosity.

[0106] Determination of residual monomer content:

[0107] The residual monomer content was determined according to the method for determining the residual acrylamide content in polyacrylamide in GB 12005.3-1989.

[0108] Testing method for dissolution time:

[0109] The viscosity was tested every minute, and the time when the viscosity reached 80% of the final viscosity was taken as the dissolution time.

[0110] Example 1

[0111] (1) Preparation of highly active lignin: 60.98 g of water and 0.02 g of concentrated sulfuric acid (96 wt%) were added to a polytetrafluoroethylene autoclave and stirred evenly; then, 18.5 g of enzymatically hydrolyzed lignin was added under stirring, the temperature of the system was raised to 75 °C, and the system was sealed and reacted for 2.5 h; 20.5 g of phenol was further added, the temperature of the system was raised to 115 °C, and the system was sealed and continuously stirred and reacted for 3 h; after the reaction was completed, petroleum ether was added to precipitate the product, and water was added to precipitate the modified product, and the product highly active lignin was obtained by centrifugal separation, washing, and vacuum drying.

[0112] (2) Preparation of modified lignin surfactant A: 26.0 g of highly active lignin was added to a polytetrafluoroethylene autoclave containing 64.6 g of water and stirred evenly, and sodium hydroxide was added to adjust the pH value of the system to 11.2; the temperature of the system was raised to 63 °C, and the pressure was reduced to a vacuum degree of -0.15 MPa (the autoclave carried out a negative pressure reaction, just connect a vacuum pump), 2.6 g of propylene oxide was added, and the reaction was stopped after 1 h. After the system was cooled to room temperature, hydrochloric acid was added to adjust the pH of the reaction system to 7.0, and the modified lignin surfactant A was obtained by separation and purification.

[0113] (3) Preparation of Modified Lignin Surfactant B: Add 24.5 g of highly active lignin into a polytetrafluoroethylene high-pressure reactor containing 70.9 g of water, and stir evenly; add 2.5 g of catalyst WO3 / ZrO2 and 2.1 g of oleic acid, heat the system to 170 °C, stop the reaction after reacting for 6 h, cool the system to room temperature, and separate and purify to obtain modified lignin surfactant B.

[0114] (4) Mix 2.5 g of modified lignin surfactant A and 7.5 g of modified lignin surfactant B evenly to obtain a lignin-based composite emulsifier.

[0115] Form an oil solution by mixing 8 g of the lignin-based composite emulsifier with 80 g of white oil; dissolve 90 g of acrylamide in 70 g of water, adjust the pH to 7 with hydrochloric acid, then add 0.02 g of disodium ethylenediaminetetraacetate and 0.01 g of ammonium persulfate and dissolve completely to form an aqueous solution; mix the oil solution and the aqueous solution, and emulsify at high speed to form a water-in-oil emulsion; after deoxygenating the water-in-oil emulsion, slowly drop in 1 g of a 1 wt% aqueous solution of sodium bisulfite to carry out a polymerization reaction on the water-in-oil emulsion, control the reaction temperature not to exceed 35 °C, and stop the reaction when the system no longer continues to heat up; obtain an acrylamide-based polymer emulsion.

[0116] The gel content of the emulsion obtained by the above method is 0.8 wt%, the dissolution time is 1 min, it stratifies after storing at room temperature for 150 days, the viscosity-average molecular weight of the polymer is 21.5 million, and the residual monomer content is 0.05 wt%.

[0117] Example 2

[0118] (1) Preparation of Highly Active Lignin: Add 54.995 g of water and 0.005 g of concentrated hydrochloric acid (36 wt%) into a polytetrafluoroethylene high-pressure reactor, and stir evenly; then, add 30 g of alkali lignin with stirring, heat the system to 65 °C, and react in a closed system for 1.5 h; continue to add 15 g of hydroquinone, heat the system to 90 °C, and continue to stir and react in a closed system for 1.5 h; after the reaction is completed, add petroleum ether to precipitate the product, add water to precipitate the modified product, and obtain the product highly active lignin through centrifugal separation, washing, and vacuum drying.

[0119] (2) Preparation of Modified Lignin Surfactant A: Add 26.0 g of highly active lignin into a polytetrafluoroethylene high-pressure reactor containing 64.6 g of water, stir evenly, and add sodium hydroxide to adjust the pH value of the system to 11.2; heat the system to 63 °C, reduce the pressure to a vacuum degree of -0.15 MPa, add 2.4 g of propylene oxide, stop the reaction after reacting for 1 h, cool the system to room temperature, then add hydrochloric acid to adjust the pH to 7.0, and separate and purify to obtain modified lignin surfactant A.

[0120] (3) Preparation of modified lignin surfactant B: Add 24.5 g of high-activity lignin into a polytetrafluoroethylene autoclave containing 70.9 g of water, and stir evenly; add 2.5 g of catalyst WO3 / ZrO2 and 2.1 g of oleic acid, heat the system to 170 °C, stop the reaction after 6 h, cool the system to room temperature, and separate and purify to obtain modified lignin surfactant B.

[0121] (4) Mix 2.5 g of modified lignin surfactant A and 7.5 g of modified lignin surfactant B evenly to obtain a lignin-based composite emulsifier.

[0122] Use the lignin-based composite emulsifier in the process of inverse emulsion synthesis of acrylamide polymers by the same method as in Example 1. The gel content of the obtained emulsion product is 1.1 wt%, the dissolution time is 3 min, it stratifies after storing at room temperature for 130 days, the viscosity-average molecular weight of the polymer is 21 million, and the residual monomer content is 0.06 wt%.

[0123] Example 3

[0124] (1) Preparation of high-activity lignin: Add 60.98 g of water and 0.02 g of concentrated sulfuric acid (96 wt%) into a polytetrafluoroethylene autoclave, and stir evenly; then, add 18.5 g of enzymatically hydrolyzed lignin with stirring, heat the system to 75 °C, and react in a closed system for 2.5 h; continue to add 20.5 g of phenol, heat the system to 115 °C, and continue to stir and react in a closed system for 3 h; after the reaction is completed, add petroleum ether to precipitate the product, add water to precipitate the modified product, and obtain the product high-activity lignin by centrifugal separation, washing, and vacuum drying.

[0125] (2) Preparation of modified lignin surfactant A: Add 30.0 g of high-activity lignin into a polytetrafluoroethylene autoclave containing 63.35 g of water, stir evenly, and add sodium hydroxide to adjust the pH value of the system to 10.5; heat the system to 50 °C, reduce the pressure to a vacuum of -0.1 MPa, add 0.15 g of propylene oxide, stop the reaction after 0.5 h, cool the system to room temperature, and then add hydrochloric acid to adjust the pH to 6.5, and separate and purify to obtain modified lignin surfactant A.

[0126] (3) Preparation of modified lignin surfactant B: Add 24.5 g of high-activity lignin into a polytetrafluoroethylene autoclave containing 70.9 g of water, and stir evenly; add 2.5 g of catalyst WO3 / ZrO2 and 2.1 g of oleic acid, heat the system to 170 °C, stop the reaction after 6 h, cool the system to room temperature, and separate and purify to obtain modified lignin surfactant B.

[0127] (4) Mix 2.5 g of modified lignin surfactant A and 7.5 g of modified lignin surfactant B evenly to obtain a lignin-based composite emulsifier.

[0128] Use the lignin-based composite emulsifier in the process of inverse emulsion synthesis of acrylamide polymers in the same method as in Example 1. The gel content of the obtained emulsion product is 1.0 wt%, the dissolution time is 2 min, it stratifies after storing at room temperature for 135 days, the viscosity-average molecular weight of the polymer is 20.8 million, and the residual monomer content is 0.07 wt%.

[0129] Example 4

[0130] (1) Preparation of highly active lignin: Add 60.98 g of water and 0.02 g of concentrated sulfuric acid (96 wt%) into a polytetrafluoroethylene high-pressure reaction kettle, and stir evenly; then, add 18.5 g of enzymatically hydrolyzed lignin under stirring, heat the system to 75 °C, and react in a closed system for 2.5 h; continue to add 20.5 g of phenol, heat the system to 115 °C, and continue to stir and react in a closed system for 3 h; after the reaction is completed, add petroleum ether to precipitate the product, add water to precipitate the modified product, and obtain the product highly active lignin through centrifugal separation, washing, and vacuum drying.

[0131] (2) Preparation of modified lignin surfactant A: Add 26.0 g of highly active lignin into a polytetrafluoroethylene high-pressure reaction kettle containing 64.6 g of water, stir evenly, and add sodium hydroxide to adjust the pH value of the system to 11.2; heat the system to 63 °C, reduce the pressure to a vacuum of -0.15 MPa, add 2.6 g of propylene oxide, stop the reaction after 1 h, cool the system to room temperature, and then add hydrochloric acid to adjust the pH to 7.0, and separate and purify to obtain modified lignin surfactant A.

[0132] (3) Preparation of modified lignin surfactant B: Add 30.0 g of highly active lignin into a polytetrafluoroethylene high-pressure reaction kettle containing 68.5 g of water, stir evenly; add 1.0 g of catalyst SO4 2- / ZrO2 and 0.5 g of stearic acid, heat the system to 150 °C, stop the reaction after 4 h, cool the system to room temperature, and separate and purify to obtain modified lignin surfactant B.

[0133] (4) Mix 2.5 g of modified lignin surfactant A and 7.5 g of modified lignin surfactant B evenly to obtain a lignin-based composite emulsifier.

[0134] The lignin-based composite emulsifier was used in the process of inverse emulsion polymerization to synthesize acrylamide polymers in the same way as in Example 1. The gel content of the obtained emulsion product was 1.2 wt%, the dissolution time was 3 min, the emulsion was stratified after being stored at room temperature for 140 days, the viscosity-average molecular weight of the polymer was 20 million, and the residual monomer content was 0.08 wt%.

[0135] Example 5

[0136] The experiment was carried out according to the method of Example 1. The difference was that 2 g of modified lignin surfactant A and 8 g of modified lignin surfactant B were mixed evenly to obtain an environmentally friendly emulsifier.

[0137] The gel content of the obtained emulsion product was 0.83 wt%, the dissolution time was 2 min, the emulsion was stratified after being stored at room temperature for 145 days, the viscosity-average molecular weight of the polymer was 21 million, and the residual monomer content was 0.08 wt%.

[0138] Example 6

[0139] The experiment was carried out according to the method of Example 1. The difference was that

[0140] 3.5 g of modified lignin surfactant A and 6.5 g of modified lignin surfactant B were mixed evenly to obtain an environmentally friendly emulsifier.

[0141] The gel content of the obtained emulsion product was 1.14 wt%, the dissolution time was 2 min, the emulsion was stratified after being stored at room temperature for 140 days, the viscosity-average molecular weight of the polymer was 21.8 million, and the residual monomer content was 0.09 wt%.

[0142] Comparative Example 1

[0143] The experiment was carried out according to the method of Example 1. The difference was that enzymatically hydrolyzed lignin was replaced by sodium lignosulfonate. The gel content of the obtained emulsion product was 8.8 wt%, the dissolution time was 7 min, the emulsion was stratified after being stored at room temperature for 15 days, the viscosity-average molecular weight of the polymer was 16.5 million, and the residual monomer content was 0.35 wt%.

[0144] Comparative Example 2

[0145] The experiment was carried out according to the method of Example 1. The difference was that 20.5 g of phenol was replaced by the same mass of water. The gel content of the obtained emulsion product was 21.5 wt%, the dissolution time was 6 min, the emulsion was stratified after being stored at room temperature for 8 days, the viscosity-average molecular weight of the polymer was 15 million, and the residual monomer content was 0.4 wt%.

[0146] Comparative Example 3

[0147] The experiment was carried out according to the method of Example 1, except that 7.5 g of modified lignin surfactant B was replaced with 7.5 g of Span 80 of the same mass. The gel content of the obtained emulsion product was 3.0 wt%, the dissolution time was 4 min, it was stratified after being stored at room temperature for 25 days, the viscosity-average molecular weight of the polymer was 14.2 million, and the residual monomer content was 0.22 wt%.

[0148] Comparative Example 4

[0149] The experiment was carried out according to the method of Example 1, except that 2.5 g of modified lignin surfactant A was replaced with modified lignin surfactant B.

[0150] The gel content of the obtained emulsion product was 3.1 wt%, the dissolution time was 10 min, it was stratified after being stored at room temperature for 18 days, the viscosity-average molecular weight of the polymer was 12 million, and the residual monomer content was 1.26 wt%.

[0151] Comparative Example 5

[0152] The experiment was carried out according to the method of Example 1, except that 7.5 g of modified lignin surfactant B was replaced with modified lignin surfactant A.

[0153] The gel content of the obtained emulsion product was 56.2 wt%, it could not be dissolved, it was stratified immediately at room temperature, the viscosity-average molecular weight of the polymer was 1.8 million, and the residual monomer content was 11.21 wt%.

[0154] Comparative Example 6

[0155] The experiment was carried out according to the method of Example 1, except that 7.5 g of modified lignin surfactant B was replaced with 7.5 g of acid-degraded phenolic modified lignin of the same mass.

[0156] The gel content of the obtained emulsion product was 42.3 wt%, it could not be dissolved, it was stratified immediately at room temperature, the viscosity-average molecular weight of the polymer was 3.6 million, and the residual monomer content was 3.98 wt%.

[0157] Comparative Example 7

[0158] The experiment was carried out according to the method of Example 1, except that 2.5 g of modified lignin surfactant A was replaced with 2.5 g of acid-degraded phenolic modified lignin of the same mass.

[0159] The gel content of the obtained emulsion product was 5.1 wt%, the dissolution time was 40 min, it was stratified after being stored at room temperature for 28 days, the viscosity-average molecular weight of the polymer was 12.1 million, and the residual monomer content was 2.09 wt%.

[0160] The present invention has been described in detail above in connection with specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions of the present invention and their implementation manners, and these all fall within the scope of the present invention. The protection scope of the present invention shall be subject to the appended claims.

[0161] All publications, patent applications, patents, and other references mentioned in this specification are hereby incorporated by reference in their entirety. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0162] When this specification uses prefixes such as "known to those skilled in the art", "prior art", or similar terms to introduce materials, substances, methods, steps, devices, or components, etc., the objects introduced by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become recognized by the art as suitable for similar purposes.

[0163] In the context of this specification, any matters or things not mentioned, except as explicitly stated, shall directly apply those known in the art without any change.

Claims

1. A lignin-based polyether, characterized in that: The lignin-based polyether is prepared by reacting raw materials including acid-degraded phenolic-modified lignin and an epoxide.

2. A preparation method of lignin-based polyether, characterized in that, It includes the following steps: Adding raw materials including acid-degraded phenolic-modified lignin and an epoxide into water for mixing, adjusting the pH, and then heating and reacting to obtain the lignin-based polyether; Preferably used for preparing the lignin-based polyether described in claim 1.

3. The preparation method of the lignin-based polyether according to claim 2, characterized in that: The epoxide is selected from at least one of ethylene oxide and propylene oxide; and / or, Adjust the pH value to 10.5 - 11.5; and / or, Based on the total mass of the acid-degraded phenolic-modified lignin, epoxide, and water added in this step being 100%, The addition amount of the acid-degraded phenolic-modified lignin is 15 - 30 wt%; The addition amount of the epoxide is 0.15 - 3 wt%; and / or, The temperature of the heating reaction is 50 - 65 °C; and / or, The time of the heating reaction is 0.5 - 1.5 h; and / or, The pressure of the heating reaction is (-0.1) - (-0.2) MPa.

4. A lignin-based composite emulsifier, characterized in that: The lignin-based composite emulsifier includes modified lignin surfactant A and modified lignin surfactant B; The modified lignin surfactant A is selected from the lignin-based polyether described in claim 1 or the lignin-based polyether described in any one of claims 2 - 3; The modified lignin surfactant B is a hydrophobic modified lignin prepared by reacting raw materials including acid-degraded phenolic-modified lignin and a long-chain acid.

5. The lignin-based composite emulsifier according to claim 4, characterized in that: In the lignin-based composite emulsifier, The content of the modified lignin surfactant A is 10 - 35 wt%; The content of the modified lignin surfactant B is 65 - 90 wt%; Preferably, The content of the modified lignin surfactant A is 20 - 30 wt%; The content of the modified lignin surfactant B is 70 - 80 wt%.

6. The lignin-based composite emulsifier according to claim 4, characterized in that: The preparation method of the modified lignin surfactant B includes: Under the action of an alkylation catalyst, heating and reacting raw materials including acid-degraded phenolic-modified lignin and a long-chain acid in water to obtain a hydrophobic modified lignin.

7. The lignin-based composite emulsifier according to claim 6, characterized in that: The alkylation catalyst is selected from solid superacids; preferably selected from at least one of SO4 2- / ZrO2 and WO3 / ZrO2, and more preferably the ZrO2 content is 80-90 wt%; and / or, The long-chain acid is selected from long-chain acids with C12 - C18; preferably selected from at least one of oleic acid, stearic acid, palmitic acid, and lauric acid; and / or, Based on the total mass of the alkylation catalyst, acid-degraded phenolic-modified lignin, long-chain acid, and water added in this step being 100%, The addition amount of the alkylation catalyst is 1 - 3 wt%; The addition amount of the long-chain acid is 0.5 - 2.5 wt%; The addition amount of the acid-degraded phenolic-modified lignin is 15 - 30 wt%; and / or, The temperature of the heating reaction is 150 - 200 °C; and / or, The time of the heating reaction is 4 - 8 h.

8. The lignin-based composite emulsifier according to claim 4, wherein: The preparation method of the acid-degraded phenolic modified lignin is as follows: Under a closed condition, after the raw materials including lignin and a degradation catalyst are subjected to a contact reaction in water, a phenolic modifier is added and the temperature is further increased for reaction, and then post-treatment is carried out to obtain the acid-degraded phenolic modified lignin; Preferably, The lignin is selected from at least one of alkali lignin and enzymatically hydrolyzed lignin; and / or, The phenolic modifier is selected from at least one of phenol and hydroquinone; and / or, The degradation catalyst is selected from strong acids, preferably selected from at least one of permanganic acid, hydrochloric acid, and sulfuric acid; and / or, Based on the total mass of lignin, phenolic modifier, degradation catalyst, and water added in this step being 100%, The addition amount of lignin is 15-30 wt%; The addition amount of the degradation catalyst is 0.005-0.02 wt%; and / or, The addition amount of the phenolic modifier is 15-25 wt%; and / or, The temperature of the contact reaction is 65-80 °C; and / or, The time of the contact reaction is 1.5-3 h; and / or, The temperature of the further temperature increase reaction is 95-125 °C; and / or, The time of the further temperature increase reaction is 1.5-4 h.

9. A preparation method of the lignin-based composite emulsifier according to any one of claims 4-8, characterized in that, It includes the following steps: The modified lignin surfactant A and the modified lignin surfactant B are mixed evenly to obtain the lignin-based composite emulsifier.

10. An acrylamide polymer emulsion, characterized in that, Using the raw materials including the lignin-based composite emulsifier, monomer, initiator, and chelating agent described in any one of claims 4-8 for inverse emulsion synthesis to obtain an acrylamide polymer emulsion.

11. A preparation method of an acrylamide polymer emulsion, wherein: The composite emulsifier is formed into an oil solution with an organic solvent; the composite emulsifier is selected from the lignin-based composite emulsifier described in any one of claims 4-8; The vinyl monomer, optionally a sulfonic acid monomer, a chelating agent, a part of the initiator, and water are mixed to form an aqueous solution; The oil solution and the aqueous solution are mixed to form a water-in-oil emulsion; After the water-in-oil emulsion is deoxygenated, the remaining initiator is added for polymerization reaction to obtain an acrylamide polymer emulsion; Preferably, this method is used to prepare the acrylamide polymer emulsion described in claim 10.

12. The preparation method of the acrylamide polymer emulsion according to claim 11, wherein: The organic solvent is selected from at least one of white oil and kerosene; and / or, The mass ratio of the organic solvent to the composite emulsifier is 1:0.05-0.2; and / or, The vinyl monomer is selected from at least one of acrylamide, acrylic acid, and N-isopropylacrylamide; and / or, The sulfonic acid monomer is selected from at least one of 2-acrylamido-2-methylpropanesulfonic acid and 2-acryloyloxy-2-methylpropanesulfonic acid; and / or, The chelating agent is selected from at least one of disodium ethylenediaminetetraacetate and trisodium ethylenediaminetetraacetate; and / or, The initiator is selected from at least one of redox initiators and azo initiators; and / or, In the aqueous solution, The content of the vinyl monomer is 40-60 wt%; The content of the sulfonic acid monomer is 0-50 wt%; The content of the chelating agent is 0.01 - 0.1 wt%; The content of the added part of the initiator is 0.01 - 0.1 wt%; and / or, The mass ratio of the part of the initiator to the remaining initiator is 1 - 4:1; and / or, The mass ratio of the aqueous solution to the oil solution is 1 - 3:1; and / or, The temperature of the polymerization reaction does not exceed 40°C; preferably, the temperature of the polymerization reaction does not exceed 35°C; and / or, The time of the polymerization reaction is 2 - 6 h.

13. Application of an acrylamide polymer emulsion as described in claim 10 or an acrylamide polymer emulsion prepared by the method as described in any one of claims 11 - 12 in oil exploitation.