Modified lignin surfactant, environment-friendly compound emulsifier, and preparation method and application of modified lignin surfactant and environment-friendly compound emulsifier

Abstract

The invention discloses a modified lignin surfactant, an environment-friendly compound emulsifier and a preparation method and application thereof. The modified lignin surfactant disclosed by the invention is obtained by sequentially reacting acid-degraded phenolated modified lignin with raw materials including epoxy haloalkane and polyhydric alcohol, and is marked as a modified lignin surfactant A; or the modified lignin surfactant is obtained by reaction of raw materials including acid-degraded phenolated modified lignin and long-chain acid, and is marked as a modified lignin surfactant B. And uniformly mixing the modified lignin surfactant A and the modified lignin surfactant B to obtain the environment-friendly compound emulsifier. The environment-friendly composite emulsifier can be applied to the inverse emulsion synthesis process of an acrylamide polymer and can well emulsify and stabilize a polymerization reaction system, and after the acrylamide polymer is injected underground, a phenylpropane structure of lignin can well emulsify crude oil, so that emulsification and extraction of the crude oil are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of emulsifiers. Further, it relates to modified lignin surfactants, environmentally friendly composite emulsifiers, and their preparation methods and applications. Background Art

[0002] In the future, the manufacturing industry of bulk oilfield chemicals will mainly develop towards the direction of efficient resource utilization, diversified raw materials, high-value products, and low-carbon and green processes. Compared with traditional petrochemical refining and chemical synthesis methods, biomanufacturing has the characteristics of being green, efficient, mild, low-carbon, and sustainable, which conforms to the strategic development plan of "carbon peak and carbon neutrality". It has become a global strategic emerging industry and shows a rapid growth trend.

[0003] Lignin has the second largest reserves in nature after cellulose and 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.

[0004] 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 types of bonds have small molecular polarity and high bond energy, making them 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 reactivity. 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

[0005] To solve the problems in the prior art, the present invention provides modified lignin surfactants, environmentally friendly composite emulsifiers, and their preparation methods and applications. The composite emulsifier of the present invention comprises modified lignin surfactant A and modified lignin surfactant B. Among them, modified lignin surfactant A is obtained by first degrading lignin to improve its activity and then reacting with epichlorohydrin and polyols; modified lignin surfactant B is obtained by first degrading lignin to improve its activity and then modifying it with long-chain alkyl groups.

[0006] The environmentally friendly 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, all of which 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.

[0007] When the environmentally friendly composite emulsifier of the present invention is used in the process of inverse emulsion synthesis of acrylamide polymers, 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. 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 modified lignin surfactant, which is obtained by reacting raw materials including acid-degraded phenolic-modified lignin with epihalohydrin and polyol in sequence, denoted as modified lignin surfactant A; or,

[0009] The modified lignin surfactant is obtained by reacting raw materials including acid-degraded phenolic-modified lignin and long-chain acid, denoted as modified lignin surfactant B.

[0010] Another purpose of the present invention is to provide a preparation method of a modified lignin surfactant, including the following steps:

[0011] The preparation method of modified lignin surfactant A includes the following steps:

[0012] Step (A): Add acid-degraded phenolic-modified lignin into water, adjust the pH, add epihalohydrin and carry out a heating reaction to obtain lignin ether;

[0013] Step (B): Carry out a contact reaction between lignin ether and polyol in water to obtain a modified lignin surfactant;

[0014] Or,

[0015] The preparation method of modified lignin surfactant B includes the following steps:

[0016] Under the action of an alkylation catalyst, add raw materials including acid-degraded phenolic-modified lignin and long-chain acid into water and carry out a closed heating reaction to obtain modified lignin surfactant B.

[0017] In the preparation method of the modified lignin surfactant of the present invention, preferably,

[0018] In step (A) of the preparation method of the modified lignin surfactant A,

[0019] the epoxy haloalkane is selected from epichlorohydrin; and / or,

[0020] adjust the pH value to 12.5 - 13.5; and / or,

[0021] Based on the total mass of water, acid - degraded phenolic - modified lignin, and epoxy haloalkane added in this step being 100%,

[0022] the addition amount of acid - degraded phenolic - modified lignin is 40 - 60 wt%;

[0023] the addition amount of epoxy haloalkane is 2 - 5 wt%; the rest is water; and / or,

[0024] the temperature of the heating reaction is 60 - 70 °C; and / or,

[0025] the time of the heating reaction is 2 - 8 h.

[0026] In the preparation method of the modified lignin surfactant of the present invention, preferably,

[0027] In step (B) of the preparation method of the modified lignin surfactant A,

[0028] the polyol is selected from at least one of pentaerythritol and glycerol; and / or,

[0029] Based on the total mass of water, lignin ether, and polyol added in this step being 100%,

[0030] the addition amount of lignin ether is 40 - 60 wt%;

[0031] the addition amount of polyol is 1 - 3 wt%; the rest is water; and / or,

[0032] the temperature of the contact reaction is 30 - 45 °C; and / or,

[0033] the time of the contact reaction is 1 - 4 h.

[0034] In the preparation method of the modified lignin surfactant of the present invention, preferably,

[0035] In the preparation method of the modified lignin surfactant B, the alkylation catalyst is selected from solid superacids; preferably, the alkylation catalyst is selected from at least one of SO4 2- / ZrO2, WO3 / ZrO2; preferably, the ZrO2 content is 80 - 90 wt%; and / or,

[0036] The long-chain acid is selected from long-chain acids with 12 to 18 carbon atoms; preferably, the long-chain acid is selected from at least one of oleic acid, stearic acid, palmitic acid, and lauric acid; and / or,

[0037] Based on the total mass of the alkylation catalyst, acid-degraded phenolic lignin, long-chain acid, and water added in this step being 100%,

[0038] the addition amount of the alkylation catalyst is 1-3 wt%;

[0039] the addition amount of the long-chain acid is 0.5-2.5 wt%;

[0040] the addition amount of the acid-degraded phenolic lignin is 15-30 wt%; the balance is water; and / or,

[0041] the temperature of the heating reaction is 150-200 °C; and / or,

[0042] the time of the heating reaction is 4-8 h.

[0043] In the preparation method of the modified lignin surfactant described in the present invention, preferably,

[0044] the preparation method of the acid-degraded phenolic modified lignin includes:

[0045] Under airtight 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 modified phenolic lignin;

[0046] Preferably,

[0047] the lignin is selected from at least one of alkali lignin and enzymatically hydrolyzed lignin; and / or,

[0048] the phenolic modifier is selected from at least one of phenol and hydroquinone; and / or,

[0049] the degradation catalyst is selected from strong acids, preferably selected from at least one of permanganic acid, hydrochloric acid, and sulfuric acid.

[0050] In the preparation method of the modified lignin surfactant described in the present invention, preferably,

[0051] Based on the total mass of the lignin, phenolic modifier, degradation catalyst, and water added in this step being 100%,

[0052] the addition amount of the lignin is 15-30 wt%;

[0053] the addition amount of the degradation catalyst is 0.005-0.02 wt%;

[0054] The addition amount of the phenolic modifier is 15 - 25 wt%; the balance is water; and / or,

[0055] The temperature of the contact reaction is 65 - 80 °C; and / or,

[0056] The contact reaction time is 1.5 - 3 h; and / or,

[0057] The temperature of the continued heating reaction is 95 - 125 °C; and / or,

[0058] The time of the continued heating reaction is 1.5 - 4 h.

[0059] The third object of the present invention is to provide an environmentally friendly composite emulsifier, and the environmentally friendly composite emulsifier includes a modified lignin surfactant A and a modified lignin surfactant B;

[0060] The modified lignin surfactant A and the modified lignin surfactant B are selected from the modified lignin surfactants described in the first object of the present invention.

[0061] In the environmentally friendly composite emulsifier described in the present invention, preferably,

[0062] In the environmentally friendly composite emulsifier,

[0063] The content of the modified lignin surfactant A is 20 - 40 wt%;

[0064] The content of the modified lignin surfactant B is 60 - 80 wt%;

[0065] Preferably,

[0066] The content of the modified lignin surfactant A is 30 - 35 wt%;

[0067] The content of the modified lignin surfactant B is 65 - 70 wt%.

[0068] The fourth object of the present invention is to provide a preparation method of the environmentally friendly composite emulsifier described in any one of the third objects of the present invention, including the following steps:

[0069] Mix the modified lignin surfactant A and the modified lignin surfactant B evenly to obtain the environmentally friendly composite emulsifier.

[0070] The fifth object of the present invention is to provide an acrylamide polymer emulsion, which is prepared by inverse emulsion synthesis using raw materials including the environmentally friendly composite emulsifier, monomer, initiator, and chelating agent described in any one of the third objects of the present invention to obtain the acrylamide polymer emulsion.

[0071] A sixth object of the present invention is to provide a method for preparing an acrylamide polymer emulsion, comprising forming an oil solution from the environment-friendly composite emulsifier and an organic solvent; the environment-friendly composite emulsifier is selected from the environment-friendly composite emulsifiers described in any one of the fourth objects of the present invention;

[0072] Mixing a vinyl monomer, optionally a sulfonic acid monomer, a chelating agent, a partial initiator and water to form an aqueous solution;

[0073] Mixing the oil solution and the aqueous solution to form a water-in-oil emulsion;

[0074] After deoxygenating the water-in-oil emulsion, adding the remaining initiator for polymerization reaction to obtain an acrylamide polymer emulsion;

[0075] Preferably, it is used for preparing the acrylamide polymer emulsion described in the fifth object of the present invention.

[0076] In the method for preparing the acrylamide polymer emulsion described in the present invention, preferably,

[0077] The organic solvent is selected from at least one of white oil and kerosene; and / or,

[0078] The mass ratio of the organic solvent to the environment-friendly composite emulsifier is 1:0.05 - 0.2; and / or,

[0079] The vinyl monomer is selected from at least one of acrylamide, acrylic acid, and N-isopropylacrylamide; and / or,

[0080] The sulfonic acid monomer is selected from at least one of 2-acrylamido-2-methylpropanesulfonic acid and 2-acryloyloxy-2-methylpropanesulfonic acid; and / or,

[0081] The chelating agent is selected from at least one of disodium ethylenediaminetetraacetate and trisodium ethylenediaminetetraacetate; and / or,

[0082] 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,

[0083] In the aqueous solution,

[0084] The content of the vinyl monomer is 37 - 50 wt%;

[0085] The content of the sulfonic acid monomer is 0 - 50 wt%;

[0086] The content of the chelating agent is 0.008 - 0.1 wt%;

[0087] The content of the partial initiator added is 0.004 - 0.1 wt%; and / or,

[0088] The mass ratio of the partial initiator to the remaining initiator is 1 - 4:1; and / or,

[0089] The mass ratio of the aqueous solution to the oil solution is 1 - 3:1; and / or,

[0090] 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,

[0091] The time of the polymerization reaction is 2 - 6 h.

[0092] The seventh object of the present invention is to provide an application of an acrylamide polymer emulsion as described in the fifth object of the present invention or an acrylamide polymer emulsion prepared by the method described in any one of the sixth objects of the present invention in oil exploitation.

[0093] In the present invention, preferably, the acid-degraded phenolic modified lignin is prepared by the following method: under certain temperature and airtight conditions, lignin is subjected to a dynamic and 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, which is separated, washed, and dried to obtain highly active lignin (i.e., acid-degraded phenolic modified lignin); preferably, the organic solvent can be a conventional organic reagent that can dissolve lignin and is insoluble in water, and is selected from at least one of petroleum ether, ethyl acetate, diethyl ether, and acetone.

[0094] 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, and oxalic acid; the basic substance is sodium hydroxide, potassium hydroxide, etc.

[0095] In the present invention, the purification method can be a conventional purification method in the art.

[0096] In the present invention, there is no particular limitation on the mixing of the modified lignin surfactant A and the modified lignin surfactant B, and it is only necessary to mix them evenly.

[0097] In the present invention, the endpoints and any values within the disclosed ranges are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values 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.

[0098] Compared with the prior art, the present invention has the following advantages:

[0099] The present invention provides an environmentally friendly composite emulsifier, a preparation method thereof and an application. The environmentally friendly composite emulsifier in 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 reacting with an epoxy haloalkane (such as epichlorohydrin) and a polyol; the modified lignin surfactant B is obtained by first degrading lignin to improve its activity and then modifying it with a long-chain alkyl group. 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 phenolization modifier, the content of phenolic hydroxyl groups in lignin can be greatly increased, further improving the conversion rate of lignin in subsequent modification. When the environmentally friendly 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.

[0100] Both the modified lignin surfactant A and the modified lignin surfactant B of the present invention are non-ionic surfactants. Compared with conventional petroleum-based small molecule emulsifiers, they have good emulsifying performance, hard water resistance and low foaming property. The aromatic ring structure of lignin itself is similar to the structure of asphaltenes in heavy oil, and it has an oil washing effect after being injected underground. The two macromolecular modified lignins synergistically enhance each other to form an emulsifying system with a complex three-dimensional structure, improving the stability and efficiency of the emulsifying system. Detailed Embodiments

[0101] 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 for further illustration of the present invention and cannot be construed 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.

[0102] In addition, it should be noted that in the following detailed embodiments, the various specific technical features described can be combined in any suitable way without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0103] In addition, any combination can be made between different embodiments 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 disclosure of this specification and also fall within the protection scope of the present invention.

[0104] Source of raw materials:

[0105] Enzymatic lignin was purchased from Shandong Lonli Biological Technology Co., Ltd., and the effective lignin content was 94.8 wt%.

[0106] Alkali lignin was purchased from J&K Scientific Ltd.

[0107] The catalyst WO3 / ZrO2 was purchased from Beijing Innochem Science & Technology Co., Ltd.;

[0108] The catalyst SO4 2- / ZrO2 was purchased from Beijing Innochem Science & Technology Co., Ltd.;

[0109] Other raw materials of the present invention are all conventional commercially available products.

[0110] Testing method:

[0111] Molecular weight test:

[0112] The intrinsic viscosity was measured 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.

[0113] Determination of residual monomer content:

[0114] The residual monomer content was measured according to the method for determining the residual acrylamide content in polyacrylamide in GB 12005.3 - 1989.

[0115] Testing method for dissolution time:

[0116] The viscosity was measured every minute, and the time when the viscosity reached 80% of the final viscosity was taken as the dissolution time.

[0117] Example 1

[0118] (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 enzymatic lignin was added with 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 added continuously, the temperature of the system was raised to 115 °C, and the system was sealed and stirred and reacted for another 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 (i.e., acid - degraded phenolic - modified lignin) was obtained through centrifugal separation, washing, and vacuum drying.

[0119] (2) Preparation of modified lignin surfactant A: Dissolve 48.0 g of high-activity lignin in 48.4 g of water, add sodium hydroxide to adjust the pH value of the reaction system to 13.2, and stir until completely dissolved; heat the system to 68 °C, add 3.6 g of epichlorohydrin, stop the reaction after reacting for 6 h, cool the system to room temperature, and separate and purify to obtain an etherification product; take 5 g of the etherification product and add it to 4.84 g of water, heat the system to 40 °C, add 0.16 g of glycerol, stop the reaction after reacting for 2.5 h, cool the system to room temperature, 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 to a high-pressure reaction kettle with polytetrafluoroethylene 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.

[0121] (4) Mix 2.56 g of modified lignin surfactant A and 5.44 g of modified lignin surfactant B evenly to obtain an environmentally friendly composite emulsifier.

[0122] Form an oil solution by mixing 10 g of the environmentally friendly composite emulsifier with 90 g of white oil; dissolve 80 g of acrylamide and 20 g of AMPS (2-acrylamido-2-methylpropanesulfonic acid) in 100 g of water, adjust the pH to 7, then add 0.02 g of disodium ethylenediaminetetraacetate and 0.013 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 emulsion containing acrylamide polymers.

[0123] The gel content of the emulsion product obtained by the above method is 0.6 wt%, the dissolution time is 1 min, it layers after storing at room temperature for 160 days, the viscosity-average molecular weight of the polymer is 19.8 million, and the residual monomer content is 0.06 wt%.

[0124] Example 2

[0125] (1) Preparation of highly active lignin: Add 54.995 g of water and 0.005 g of concentrated hydrochloric acid (concentration 36 wt%) into a polytetrafluoroethylene high-pressure reactor, and stir evenly; then, add 30 g of alkali lignin under 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.

[0126] (2) Preparation of modified lignin surfactant A: Dissolve 48.0 g of highly active lignin in 48.4 g of water, add sodium hydroxide to adjust the pH value of the system to 13.2, and stir until completely dissolved; heat the system to 68 °C, add 3.6 g of epichlorohydrin, stop the reaction after reacting for 6 h, cool the system to room temperature, and separate and purify to obtain the etherification product; take 5 g of the etherification product and add it to 4.84 g of water, heat the system to 40 °C, add 0.16 g of glycerol, stop the reaction after reacting for 2.5 h, cool the system to room temperature, and separate and purify to obtain modified lignin surfactant A.

[0127] (3) Preparation of modified lignin surfactant B: Add 24.5 g of highly active lignin into a high-pressure reactor with polytetrafluoroethylene 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, wash, and dry to obtain modified lignin surfactant B.

[0128] (4) Mix 2.56 g of modified lignin surfactant A and 5.44 g of modified lignin surfactant B evenly to obtain an environmentally friendly composite emulsifier.

[0129] Use the environmentally friendly 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 0.9 wt%, the dissolution time is 2 min, it stratifies after storing at room temperature for 155 days, the viscosity-average molecular weight of the polymer is 19 million, and the residual monomer content is 0.09 wt%.

[0130] Example 3

[0131] (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 reactor, 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 of highly active lignin through centrifugal separation, washing, and vacuum drying.

[0132] (2) Preparation of modified lignin surfactant A: Dissolve 60.0 g of highly active lignin in 38.0 g of water, add sodium hydroxide to adjust the pH value of the system to 12.5, and stir until completely dissolved. Heat the system to 60 °C, add 2 g of epichlorohydrin, stop the reaction after 2 h, cool the system to room temperature, and separate and purify to obtain the etherification product. Take 6 g of the etherification product and add it to 3.9 g of water, heat the system to 40 °C, add 0.1 g of pentaerythritol, stop the reaction after 1 h, cool the system to room temperature, and separate and purify to obtain modified lignin surfactant A.

[0133] (3) Preparation of modified lignin surfactant B: Add 24.5 g of highly active lignin into a high-pressure reactor with polytetrafluoroethylene 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, wash, and dry to obtain modified lignin surfactant B.

[0134] (4) Mix 2.56 g of modified lignin surfactant A and 5.44 g of modified lignin surfactant B evenly to obtain an environmentally friendly composite emulsifier.

[0135] Use the environmentally friendly 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 3 min, it stratifies after storing at room temperature for 145 days, the viscosity-average molecular weight of the polymer is 18.8 million, and the residual monomer content is 0.1 wt%.

[0136] Example 4

[0137] (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 autoclave, 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.

[0138] (2) Preparation of modified lignin surfactant A: Dissolve 48.0 g of highly active lignin in 48.4 g of water, add sodium hydroxide to adjust the pH value of the system to 13.2, and stir until completely dissolved; heat the system to 68 °C, add 3.6 g of epichlorohydrin, stop the reaction after 6 h, cool the system to room temperature, and separate and purify to obtain the etherification product; take 5 g of the etherification product and add it to 4.84 g of water, heat the system to 40 °C, add 0.16 g of glycerol, stop the reaction after 2.5 h, cool the system to room temperature, and separate and purify to obtain modified lignin surfactant A.

[0139] (3) Preparation of modified lignin surfactant B: Add 30.0 g of highly active lignin into a polytetrafluoroethylene autoclave containing 68.5 g of water, and 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, wash, and dry to obtain modified lignin surfactant B.

[0140] (4) Mix 2.56 g of modified lignin surfactant A and 5.44 g of modified lignin surfactant B evenly to obtain an environmentally friendly composite emulsifier.

[0141] Use the environmentally friendly 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 0.8 wt%, the dissolution time is 2 min, it stratifies after storing at room temperature for 152 days, the viscosity-average molecular weight of the polymer is 19.5 million, and the residual monomer content is 0.08 wt%.

[0142] Example 5

[0143] Conduct experiments according to the method of Example 1, except that

[0144] Mix 2 g of modified lignin surfactant A and 8 g of modified lignin surfactant B evenly to obtain an environmentally friendly composite emulsifier.

[0145] When an environmentally friendly composite emulsifier is used in the process of synthesizing acrylamide polymers by inverse emulsion, the gel content of the resulting emulsion product is 0.7 wt%, the dissolution time is 1 min, it stratifies after storage at room temperature for 165 days, the viscosity-average molecular weight of the polymer is 17.4 million, and the residual monomer content is 0.09 wt%.

[0146] Example 6

[0147] The experiment was carried out according to the method of Example 1, except that

[0148] 4 g of modified lignin surfactant A and 6 g of modified lignin surfactant B were mixed evenly to obtain an environmentally friendly composite emulsifier.

[0149] When the environmentally friendly composite emulsifier is used in the process of synthesizing acrylamide polymers by inverse emulsion, the gel content of the resulting emulsion product is 1.2 wt%, the dissolution time is 3 min, it stratifies after storage at room temperature for 130 days, the viscosity-average molecular weight of the polymer is 20.9 million, and the residual monomer content is 0.12 wt%.

[0150] Comparative Example 1

[0151] The experiment was carried out according to the method of Example 1, except that enzymatically hydrolyzed lignin was replaced by sodium lignosulfonate. The gel content of the resulting emulsion product was 6.9 wt%, the dissolution time was 6 min, it stratifies after storage at room temperature for 24 days, the viscosity-average molecular weight of the polymer was 13.4 million, and the residual monomer content was 0.4 wt%.

[0152] Comparative Example 2

[0153] The experiment was carried out according to the method of Example 1, except that 20.5 g of phenol was replaced by the same mass of water. The gel content of the resulting emulsion product was 17.5 wt%, the dissolution time was 27 min, it stratifies after storage at room temperature for 5 days, the viscosity-average molecular weight of the polymer was 14.2 million, and the residual monomer content was 0.54 wt%.

[0154] Comparative Example 3

[0155] The experiment was carried out according to the method of Example 1, except that 2.56 g of modified lignin surfactant A was replaced by the same mass of modified lignin surfactant B.

[0156] When the environmentally friendly composite emulsifier is used in the process of synthesizing acrylamide polymers by inverse emulsion, the gel content of the resulting emulsion product is 12.5 wt%, the dissolution time is 25 min, it stratifies after storage at room temperature for 3 days, the viscosity-average molecular weight of the polymer is 4.5 million, and the residual monomer content is 0.14 wt%.

[0157] Comparative Example 4

[0158] The experiment was conducted according to the method of Example 1, except that 5.44 g of modified lignin surfactant B was replaced with an equal mass of modified lignin surfactant A.

[0159] When the environmentally friendly composite emulsifier was used in the process of synthesizing acrylamide polymers by inverse emulsion, the gel content of the obtained emulsion product was 45.2 wt%, it could not be dissolved, and it immediately stratified at room temperature. The viscosity-average molecular weight of the polymer was 2.9 million, and the residual monomer content was 2.55 wt%.

[0160] Comparative Example 5

[0161] The experiment was conducted according to the method of Example 1, except that 5.44 g of modified lignin surfactant B was replaced with an equal mass of Span 80. The gel content of the obtained emulsion product was 3.7 wt%, the dissolution time was 5 min, it stratified after being stored at room temperature for 32 days, the viscosity-average molecular weight of the polymer was 16.2 million, and the residual monomer content was 0.16 wt%.

[0162] Comparative Example 6

[0163] The experiment was conducted according to the method of Example 1, except that 5.44 g of modified lignin surfactant B was replaced with an equal mass of acid-degraded phenolic-modified lignin.

[0164] The gel content of the obtained emulsion product was 38.1 wt%, it could not be dissolved, and it immediately stratified at room temperature. The viscosity-average molecular weight of the polymer was 5.9 million, and the residual monomer content was 2.41 wt%.

[0165] Comparative Example 7

[0166] The experiment was conducted according to the method of Example 1, except that 2.56 g of modified lignin surfactant A was replaced with an equal mass of acid-degraded phenolic-modified lignin.

[0167] The gel content of the obtained emulsion product was 8.9 wt%, the dissolution time was 60 min, it stratified after being stored at room temperature for 12 days, the viscosity-average molecular weight of the polymer was 10.8 million, and the residual monomer content was 1.56 wt%.

[0168] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but 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 and implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

[0169] 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 of ordinary skill in the art. In case of conflict, the definitions in this specification shall prevail.

[0170] When materials, substances, methods, steps, devices, or components, etc. are introduced in this specification by the phrase "known to those of ordinary skill in the art", "prior art", or similar expressions, the subject matter introduced by such phrases covers those commonly used in the art at the time of filing of this application, but also includes those that are not commonly used currently, yet will become recognized in the art as suitable for similar purposes.

[0171] In the context of this specification, any matter or thing not mentioned, other than what is expressly stated, shall directly apply those known in the art without any modification.

Claims

1. A modified lignin surfactant, characterized in that: The modified lignin surfactant is obtained by reacting raw materials including acid-degraded phenolic modified lignin with epihalohydrin and polyol in sequence, denoted as modified lignin surfactant A; or, The modified lignin surfactant is obtained by reacting raw materials including acid-degraded phenolic modified lignin and long-chain acid, denoted as modified lignin surfactant B.

2. A preparation method of the modified lignin surfactant according to claim 1, characterized in that: The preparation method of modified lignin surfactant A includes the following steps: Step (A): Add acid-degraded phenolic modified lignin into water, adjust the pH, add epihalohydrin and carry out a heating reaction to obtain lignin ether; Step (B): Carry out a contact reaction between the lignin ether and polyol in water to obtain the modified lignin surfactant; Or, The preparation method of modified lignin surfactant B includes the following steps: Under the action of an alkylation catalyst, add raw materials including acid-degraded phenolic modified lignin and long-chain acid into water and carry out a sealed heating reaction to obtain modified lignin surfactant B.

3. According to the preparation method of the modified lignin surfactant described in claim 2, characterized in that: In step (A) of the preparation method of modified lignin surfactant A, The epihalohydrin is selected from epichlorohydrin; and / or, Adjust the pH value to 12.5 - 13.5; and / or, Based on the total mass of water, acid-degraded phenolic modified lignin, and epihalohydrin added in this step being 100%, The addition amount of acid-degraded phenolic modified lignin is 40 - 60 wt%; The addition amount of epihalohydrin is 2 - 5 wt%; and / or, The temperature of the heating reaction is 60 - 70 °C; and / or, The time of the heating reaction is 2 - 8 h.

4. According to the preparation method of the modified lignin surfactant described in claim 2, characterized in that: In step (B) of the preparation method of modified lignin surfactant A, The polyol is selected from at least one of pentaerythritol and glycerol; and / or, Based on the total mass of water, lignin ether, and polyol added in this step being 100%, The addition amount of lignin ether is 40 - 60 wt%; The addition amount of polyol is 1 - 3 wt%; and / or, The temperature of the contact reaction is 30 - 45 °C; and / or, The time of the contact reaction is 1 - 4 h.

5. According to the preparation method of the modified lignin surfactant described in claim 2, characterized in that: In the preparation method of modified lignin surfactant B, The alkylation catalyst is selected from solid superacids; preferably, the alkylation catalyst is selected from at least one of SO4 2- / ZrO2 and WO3 / ZrO2; and / or, The long-chain acid is selected from long-chain acids with C12 - C18; preferably, the long-chain acid is 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 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 acid-degraded phenolic 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.

6. The preparation method of the modified lignin surfactant according to claim 2, wherein: The preparation method of the acid-degraded phenolic modified lignin includes: 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 raised for reaction, and then post-treatment is carried out to obtain acid-degraded phenolic 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 at least one of permanganic acid, hydrochloric acid, and sulfuric acid.

7. The preparation method of the modified lignin surfactant according to claim 6, wherein: 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%; 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 contact reaction time is 1.5-3 h; and / or, The temperature for further heating and reaction is 95-125 °C; and / or, The time for further heating and reaction is 1.5-4 h.

8. An environment-friendly composite emulsifier, wherein: The environment-friendly composite emulsifier includes modified lignin surfactant A and modified lignin surfactant B; The modified lignin surfactant A and modified lignin surfactant B are selected from the modified lignin surfactant according to claim 1 or the modified lignin surfactant prepared by the method according to any one of claims 2-7.

9. The environment-friendly composite emulsifier according to claim 8, wherein: In the environment-friendly composite emulsifier, The content of modified lignin surfactant A is 20-40 wt%; The content of modified lignin surfactant B is 60-80 wt%; Preferably, The content of modified lignin surfactant A is 30-35 wt%; The content of modified lignin surfactant B is 65-70 wt%.

10. A preparation method of the environment-friendly composite emulsifier according to any one of claims 8-9, characterized in that, It includes the following steps: Mix modified lignin surfactant A and modified lignin surfactant B evenly to obtain the environment-friendly composite emulsifier.

11. An acrylamide polymer emulsion, characterized in that, Using the raw materials including the environment-friendly composite emulsifier according to any one of claims 8-9, monomer, initiator, and chelating agent for inverse emulsion synthesis to obtain an acrylamide polymer emulsion.

12. A preparation method of an acrylamide polymer emulsion, wherein: Form an oil solution by mixing the environment-friendly composite emulsifier with an organic solvent; the environment-friendly composite emulsifier is selected from the environment-friendly composite emulsifier according to any one of claims 8-9; Mix a vinyl monomer, optionally a sulfonic acid monomer, a chelating agent, a part of the initiator, and water to form an aqueous solution; Mix the oil solution and the aqueous solution to form a water-in-oil emulsion; After deoxygenating the water-in-oil emulsion, add the remaining initiator for polymerization reaction to obtain an acrylamide polymer emulsion; Preferably, it is used for preparing the acrylamide polymer emulsion according to claim 11.

13. The preparation method of the acrylamide polymer emulsion according to claim 12, characterized in that: 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 environment-friendly 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 37 - 50 wt%; The content of the sulfonic acid monomer is 0 - 50 wt%; The content of the chelating agent is 0.008 - 0.1 wt%; The content of the partial initiator added is 0.004 - 0.1 wt%; and / or, The mass ratio of the partial 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.

14. The application of the acrylamide polymer emulsion according to claim 11 or the acrylamide polymer emulsion prepared by the method according to any one of claims 12 - 13 in oil exploitation.