Preparation method and application of polyacrylamide derivative

Abstract

The invention relates to the technical field of chemical synthesis, in particular to a preparation method and application of a polyacrylamide derivative, and the preparation method comprises the following step: reacting polyacrylamide with aldehyde to obtain the polyacrylamide derivative. The prepared polyacrylamide derivative can be used as a desulfurizing agent to reduce sulfur-containing pollutants of crude oil, dry hydrocarbon gas, wet hydrocarbon gas, wastewater, liquid hydrocarbon, gaseous hydrocarbon, asphalt, drilling fluid and the like, the efficiency of removing hydrogen sulfide and mercaptan is high, and the problem that the efficiency of removing hydrogen sulfide and mercaptan is generally low in the existing desulfurizing agent is solved; the catalyst has thermal degradation resistance and can maintain the stability of desulfurization; in addition, the preparation method is simple in process, low in cost, green, environmentally friendly and suitable for large-scale production and application.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and in particular to a preparation method and application of a polyacrylamide derivative. Background Art

[0002] Hydrogen sulfide (H2S) and mercaptans are ubiquitous in the drilling, completion, production, transportation, storage, and processing of crude oil and natural gas, including in wastewater associated with crude oil and natural gas production, and in the storage of residual fuel oil. The presence of H2S and mercaptans can lead to oil product instability and out-of-specification conditions, pose serious health risks, and are highly corrosive to storage tanks, pipelines, and equipment. Oilfield operators have invested significant expense and effort over the years to reduce H2S and mercaptans to safe levels. While various desulfurization agents, such as glyoxal, triazines, metal-based scavengers, and other amines, have been developed, these traditional H2S desulfurization agents not only have low mercaptan removal efficiency but also often suffer from scaling and solids formation issues. Acrolein is a well-known desulfurization agent that effectively removes H2S and mercaptans from oil-based systems and mixed production systems, but it is also toxic and hazardous to handle. Current desulfurization agents suffer from limitations such as low reactivity, corrosiveness, reversibility, temperature instability, thermal degradation, ineffective mercaptan removal, and high cost.

[0003] Hydrogen sulfide and mercaptans are common contaminants in crude oil and refined oil products, with mercaptan concentrations ranging from 0 to 1000 ppm. Removal of mercaptans is particularly challenging and beneficial. Compared with H2S, mercaptans have lower acidity. For example, the pKa of H2S at 25°C is 7.0, while the acidity of C1 to C4 mercaptans is basically the same, with a pKa above 10 at 25°C (methyl mercaptan pKa: 10.4, ethyl mercaptan pKa: 10.6), which is much lower than the acidity of H2S. The weak acidity leads to the low efficiency of most desulfurization agents in removing mercaptans. To date, the choice of desulfurization agents is very narrow between efficiency and economy. Therefore, in order to simultaneously remove hydrogen sulfide and mercaptans in liquid hydrocarbon systems and mixed production to mitigate the negative impact on crude oil and finished product properties, improved desulfurization methods and innovative desulfurization agent compositions are needed.

[0004] Prior art records of amide desulfurizers include: US Patent No. 11584879B1, which discloses anionic linear polyacrylates, polyacrylamide, acrylamidomethylpropane sulfonate / acrylic acid copolymers, polymaleic acid / acrylic acid / acrylamidomethylpropane sulfonate terpolymers, and combinations thereof. Adding 0.6-10% of anionic linear polymers to a mixture of 30-60% hydroxyethyl triazine and 5-20% formaldehyde improves desulfurization efficiency by 10-30%. US Patent No. 10538710B2 discloses compounds based on tertiary amines or hydroxytertiary amines and hemiacetals, derivatives of which contain amide and urea groups. These compounds can significantly improve the gas desulfurization efficiency of hemiacetals. US Patent No. 4569766A discloses desulfurization by reacting the olefinic bonds of maleimides with hydrogen sulfide and mercaptans to form stable and harmless sulfide compounds. Patent CN115364640B discloses a ceramic membrane prepared by sintering diatomaceous earth and mullite and modifying starch with N-(2-amino-2-oxoethyl)-2-acrylamide. The ceramic membrane is used for the pretreatment of SO2-containing waste gas, and then treated with a composite desulfurizer, and the resulting waste gas has a high desulfurization efficiency. Patent CN118308134A discloses an oilfield anti-scaling desulfurizer and its preparation method. Chitosan is modified with p-methoxybenzaldehyde, grafted with acrylamide, and then hyperbranched and polymerized with diethylenetriamine terminal amino groups to obtain a polyamino compound. Activated carbon modified with this compound can significantly improve the desulfurization effect of the desulfurizer. In summary, existing patents cover polyacrylamide, maleimide, modified starch containing acrylamide groups, and modified chitosan grafted with acrylamide. There is no record of using polyacrylamide derivatives alone as desulfurizers.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method and application of a polyacrylamide derivative, which solves the problem that the current desulfurizers generally have low efficiency in removing hydrogen sulfide and mercaptans.

[0007] A first aspect of the present invention provides a method for preparing a polyacrylamide derivative, comprising the following steps: reacting polyacrylamide with aldehyde to obtain the polyacrylamide derivative.

[0008] Preferably, the method further comprises the step of reacting the obtained polyacrylamide derivative with a hydroxyl-containing compound. The addition of the hydroxyl-containing compound not only further produces the polyacrylamide derivative but also serves as a reaction solvent to dilute the reaction raw materials, reduce the surface tension of the solution, and improve reaction efficiency. Furthermore, the incompletely reacted aldehyde can be further converted into a non-toxic acrylamide derivative, thus contributing to environmental protection.

[0009] Taking the reaction of polyacrylamide, formaldehyde and methanol as an example, the specific reaction is shown in formula (I):

[0010]

[0011] Preferably, the polyacrylamide includes at least one of anionic polyacrylamide, cationic polyacrylamide and nonionic polyacrylamide.

[0012] Preferably, the aldehyde includes at least one of formaldehyde, formaldehyde hemiacetal, formaldehyde acetal, paraformaldehyde, acetaldehyde, acrolein, trioxymethylene, glyoxal, propionaldehyde, butyraldehyde, malondialdehyde, glutaraldehyde, glyoxal, and benzaldehyde.

[0013] Preferably, the molar ratio of the amide group of the polyacrylamide to the aldehyde is controlled in the range of 2:1 to 1:2.

[0014] Preferably, the hydroxyl-containing compound is an alcohol compound.

[0015] Preferably, the alcohol compound is a primary alkanol, and the molar ratio of the amide group of the polyacrylamide to the primary alkanol is controlled to be 20:1 to 1:20. The primary alkanol contains 1 to 20 carbon atoms, and the primary alkanol includes but is not limited to methanol, ethanol, propanol, isopropanol, 1-butanol, isobutanol, ethylene glycol, glycerol, 2-butoxyethanol (EGBE), etc.

[0016] Preferably, the alcohol compound is a polyol, and the molar ratio of the amide group of the polyacrylamide to the polyol repeating unit is controlled at 2:1 to 1:2. Polyol refers to an organic compound containing multiple hydroxyl groups, and the polyol includes but is not limited to polyethylene oxide, polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol, polyether polyol, acrylic polyol, acrylate polyol, polyester polyol, etc.

[0017] The second aspect of the present invention provides a polyacrylamide derivative prepared by the above-mentioned preparation method, wherein the polyacrylamide derivative has one or both structures shown in formula (II) or formula (III):

[0018]

[0019] wherein R1 represents a hydrogen atom, an alkyl group, an alkene group, an alkyne group (these groups may be linear, branched, cyclic or acyclic) or a combination thereof;

[0020] R2 represents a hydrogen atom, an alkanol, an alkylamine, an alkylamide, an alkyl ether, an alkyl ester, an alkyl carboxylic acid, an alkyl carbonate, an alkyl ketone, an alkoxy group, an alkyl halide, an aryl group, an alkyl group, an alkene, an alkyne (these groups may be linear, branched, cyclic or acyclic) or a combination thereof.

[0021] In one embodiment, R1 comprises a C1 to C20 carbon chain and R2 comprises a hydroxymethyl group.

[0022] In another embodiment, R1 comprises a C1 to C20 carbon chain and R2 comprises a methoxymethyl group.

[0023] The polyacrylamide derivative of the present invention achieves desulfurization effect by contacting with substances containing hydrogen sulfide and / or mercaptan. The desulfurization agent is water-soluble and effective in a wide range of pH and SH concentration.

[0024] The desulfurization agent of the present invention reduces or removes the above-mentioned sulfides by reacting with the sulfides, and the reactants partially or completely convert the sulfides into stable reaction products or products that may still remain but no longer have adverse effects on gas, water and hydrocarbon substrates.

[0025] The polyacrylamide derivatives of the present invention can reduce corrosion and scale formation when used as additives under certain conditions. In addition, the low reactivity of acrylamide and its derivatives makes them more suitable for use in combination with other additives.

[0026] Compared with conventional sulfide scavengers (such as triazines), the polyacrylamide derivative desulfurizer of the present invention has stronger reactivity in removing hydrogen sulfide and mercaptans in liquid hydrocarbons.

[0027] The third aspect of the present invention provides the use of the above-mentioned polyacrylamide derivative as a desulfurizing agent to reduce the concentration of sulfur-containing pollutants.

[0028] Preferably, the desulfurization scope includes but is not limited to crude oil, dry hydrocarbon gas, wet hydrocarbon gas, liquid hydrocarbons, gaseous hydrocarbons, asphalt, drilling fluids, wastewater systems, mixed production systems, etc.

[0029] For example: desulfurization in the production, transportation, storage and separation of crude oil, desulfurization and flocculation in wastewater treatment, desulfurization and viscosity increase of drilling fluids, etc.

[0030] Specifically, the sulfur pollutants contained include hydrogen sulfide, mercaptans and mixtures thereof.

[0031] Specifically, the liquid hydrocarbons include, but are not limited to, petroleum, refined products, residual fuels, crude oil, and asphalt; hydrocarbon molecules may contain heteroatoms such as oxygen, nitrogen, and sulfur.

[0032] Specifically, the wastewater includes but is not limited to wastewater from self-drilling, transportation, storage and municipal wastewater treatment facilities.

[0033] Specifically, the gaseous hydrocarbons include but are not limited to dry hydrocarbon gas, wet hydrocarbon gas, natural gas and coal gas.

[0034] Specifically, the drilling fluids are available from saltwater and freshwater drilling fluid systems, oil-based drilling fluid systems, and synthetic-based drilling fluid systems. Polyacrylamide derivatives, as hydrogen sulfide and mercaptan scavengers, improve the performance of drilling fluids by preventing degradation of fluid properties due to hydrogen sulfide and mercaptan leakage, effectively increasing drilling efficiency and overall operational success rates.

[0035] Of course, the application of the polyacrylamide derivatives of the present invention is not limited to the above fields. For example, the desulfurizer of the present invention can also be used to treat gases, water and hydrocarbons containing pollutants such as mercaptan carboxylic acids (RCO-SH), dithioacids (RCS-SH) and related compounds.

[0036] The desulfurizing agent of the present invention can be used as a single component or mixed with other additives.

[0037] The present invention has at least the following beneficial effects:

[0038] The polyacrylamide derivative prepared by the present invention can be used as a desulfurizer to reduce sulfur-containing pollutants in crude oil, dry hydrocarbon gas, wet hydrocarbon gas, wastewater, liquid hydrocarbons, gaseous hydrocarbons, asphalt, drilling fluid, etc., and has high efficiency in removing hydrogen sulfide and mercaptans, thus solving the problem of low efficiency of hydrogen sulfide and mercaptans removal generally seen in current desulfurizers. The polyacrylamide derivative also has resistance to thermal degradation and can maintain stable desulfurization performance. In addition, the preparation method of the present invention is simple in process, low in cost, and environmentally friendly, making it suitable for large-scale production applications. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular also includes the plural. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0041] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] AF307 (anionic polyacrylamide) and NF201 (nonionic polyacrylamide) used in the following examples are products of SNF Inc.

[0043] Example 1

[0044] This example provides a method for preparing a polyacrylamide derivative. The specific steps are as follows: 98.04 g of deionized water, 0.68 g of anionic polyacrylamide (AF307), and 1.17 g of a 37% aqueous formaldehyde solution are added to a three-necked round-bottom flask equipped with an electric heating mantle, a magnetic stirrer, a thermocouple, and a condenser, according to the raw material ratios listed in Table 1. Stirring is initiated, and an aqueous sodium hydroxide solution is added dropwise. The pH is adjusted to 10-11. The temperature is raised to 50°C and maintained at 50°C for 3 hours. The resulting polyacrylamide derivative has the following repeating unit structure:

[0045]

[0046] Table 1 Raw material ratio

[0047] raw material weight,% water 98.04 Anionic polyacrylamide (AF307) 0.68 Formaldehyde aqueous solution (37%) 1.18 Sodium hydroxide aqueous solution (25%) 0.10 total 100.00

[0048] Example 2

[0049] This example provides a method for preparing a polyacrylamide derivative. The specific steps are as follows: To a three-necked round-bottom flask equipped with an electric heating mantle, a magnetic stirrer, a thermocouple, and a condenser, 74.40 g of deionized water, 19.00 g of ethanol, 1.50 g of nonionic polyacrylamide (NF201), and 5.00 g of a 37% aqueous formaldehyde solution are added according to the raw material ratios shown in Table 2. Stirring is initiated, and an aqueous sodium hydroxide solution is added dropwise. The pH is adjusted to 10-11. The temperature is raised to 50°C and maintained at 50°C for 3 hours. The chemical structure of the prepared polyacrylamide derivative comprises the following repeating units:

[0050]

[0051] Table 2 Raw material ratio

[0052] raw material weight,% water 74.40 ethanol 19.00 Nonionic polyacrylamide (NF201) 1.50 Formaldehyde aqueous solution (37%) 5.00 Sodium hydroxide aqueous solution (25%) 0.10 total 100.00

[0053] Example 3

[0054] This example provides a method for preparing a polyacrylamide derivative. The specific steps are as follows: To a three-necked round-bottom flask equipped with an electric heating mantle, a magnetic stirrer, a thermocouple, and a condenser, 93.73 g of deionized water, 1.23 g of nonionic polyacrylamide (NF201), and 5.04 g of a 40% aqueous solution of glyoxal are added according to the raw material ratios listed in Table 3. Stirring is initiated, and an aqueous sodium hydroxide solution is added dropwise. The pH is adjusted to 10-11. The temperature is raised to 50°C and maintained at 50°C for 3 hours. The resulting polyacrylamide derivative has the following repeating unit structure:

[0055]

[0056] Table 3 Raw material ratio

[0057] raw material weight,% water 93.63 Nonionic polyacrylamide (NF201) 1.23 Glyoxal aqueous solution (40%) 5.04 NaOH (25%) 0.10 total 100.00

[0058] Test Example: Performance evaluation of hydrogen sulfide and mercaptan desulfurizers was conducted in accordance with ASTM D5707 and UOP163.

[0059] Nitrogen gas containing 10% hydrogen sulfide was bubbled through crude oil at room temperature for two hours. The headspace hydrogen sulfide concentration was then measured every 30 minutes using a Drager hydrogen sulfide detector until the reading stabilized. To 500 ml of sulfur-containing crude oil was added 2500 ppm of each of the following components: a 37% aqueous formaldehyde solution, a 1.5% aqueous nonionic polyacrylamide (NF201) solution, and samples from Examples 1, 2, and 3. The five samples were shaken on an orbital shaker at 100 RPM for one hour, allowed to stand for 24 hours, and then tested. Performance data are shown in Table 4. As shown in Table 4, the polyacrylamide derivatives of Examples 1-3, as desulfurization agents, effectively reduced the levels of hydrogen sulfide and mercaptans in crude oil.

[0060] Table 4 Desulfurization performance of hydrogen sulfide and mercaptan

[0061]

[0062]

[0063] Thermal degradation of hydrogen sulfide and mercaptan desulfurizers in oilfield applications has always been a huge challenge, and thermal degradation leads to a significant reduction in desulfurization efficiency. Table 5 shows a performance comparison of Example 1 before and after thermal degradation treatment. In Table 5, Sample 1A Example 1 was stored at room temperature for 5 days. Sample 1B is Example 1 stored at 70°C for 5 days. 2500ppm of Sample 1A and Sample 1B were added to the sulfur-containing crude oil, shaken on a gyroscopic oscillator at 100RPM for one hour, and tested after 24 hours. It can be seen from Table 5 that the desulfurizer based on polyacrylamide derivatives has resistance to thermal degradation. After thermal degradation treatment, the performance of hydrogen sulfide removal is improved, the performance of mercaptan removal is not significantly reduced, and the stable performance of desulfurization can be maintained.

[0064] Table 5 Comparison of hydrogen sulfide and mercaptan removal performance after thermal degradation of Example 1

[0065]

[0066] The desulfurizer of the present invention has been proven to be effective in high-sulfur crude oil systems, especially for removing mercaptans. The desulfurizer can be used in a variety of applications, including but not limited to crude oil, wastewater systems, mixed production systems, liquid hydrocarbons, asphalt, and drilling fluids.

[0067] In summary, the polyacrylamide derivative prepared by the present invention can be used as a desulfurizer to reduce sulfur-containing pollutants in crude oil, dry hydrocarbon gas, wet hydrocarbon gas, wastewater, liquid hydrocarbons, gaseous hydrocarbons, asphalt, drilling fluids, and mixed production systems, and has high efficiency in removing hydrogen sulfide and mercaptans, solving the problem of low desulfurization efficiency of current desulfurizers. It also has resistance to thermal degradation and can maintain stable desulfurization performance. In addition, the preparation method of the present invention is simple, low-cost, green and environmentally friendly, and is suitable for large-scale production applications.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polyacrylamide derivative, characterized in that: The method comprises the following steps: reacting polyacrylamide with aldehyde to obtain a polyacrylamide derivative.

2. The method for preparing the polyacrylamide derivative according to claim 1, characterized in that: The method further comprises the following step: further reacting the obtained polyacrylamide derivative with a hydroxyl-containing compound.

3. The method for preparing the polyacrylamide derivative according to claim 1, characterized in that: The polyacrylamide includes at least one of anionic polyacrylamide, cationic polyacrylamide and nonionic polyacrylamide.

4. The method for preparing a polyacrylamide derivative according to claim 1, wherein: The aldehyde includes at least one of formaldehyde, formaldehyde hemiacetal, formaldehyde acetal, paraformaldehyde, acetaldehyde, acrolein, trioxymethylene, glyoxal, propionaldehyde, butyraldehyde, malondialdehyde, glutaraldehyde, glyoxal, and benzaldehyde.

5. The method for preparing a polyacrylamide derivative according to claim 1, wherein: The molar ratio of the amide group of the polyacrylamide to the aldehyde is controlled in the range of 2:1 to 1:

2.

6. The method for preparing the polyacrylamide derivative according to claim 2, characterized in that: The hydroxyl-containing compound is an alcohol compound.

7. The method for preparing a polyacrylamide derivative according to claim 6, characterized in that: The alcohol compound is a primary alkanol, and the molar ratio of the amide group of the polyacrylamide to the primary alkanol is controlled to be 20:1 to 1:

20.

8. The method for preparing a polyacrylamide derivative according to claim 6, characterized in that: The alcohol compound is a polyol, and the molar ratio of the amide group of the polyacrylamide to the polyol repeating unit is controlled in the range of 2:1 to 1:

2.

9. A polyacrylamide derivative, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8, the polyacrylamide derivative has one or both structures shown in formula (II) or formula (III): wherein R1 represents a hydrogen atom, an alkyl group, an alkene group, an alkyne group or a combination thereof; R2 represents a hydrogen atom, an alkanol, an alkylamine, an alkylamide, an alkyl ether, an alkyl ester, an alkyl carboxylic acid, an alkyl carbonate, an alkyl ketone, an alkoxy group, an alkyl halide, an aryl group, an alkyl group, an alkene, or an alkyne.

10. The use of the polyacrylamide derivative according to claim 9, characterized in that: It is used as a desulfurizing agent to reduce the concentration of sulfur-containing pollutants.

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