CN108641010B - Preparation method of modified welan gum - Google Patents
Preparation method of modified welan gum Download PDFInfo
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- CN108641010B CN108641010B CN201810660307.2A CN201810660307A CN108641010B CN 108641010 B CN108641010 B CN 108641010B CN 201810660307 A CN201810660307 A CN 201810660307A CN 108641010 B CN108641010 B CN 108641010B
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B37/00—Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof
- C08B37/006—Heteroglycans, i.e. polysaccharides having more than one sugar residue in the main chain in either alternating or less regular sequence; Gellans; Succinoglycans; Arabinogalactans; Tragacanth or gum tragacanth or traganth from Astragalus; Gum Karaya from Sterculia urens; Gum Ghatti from Anogeissus latifolia; Derivatives thereof
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Abstract
The invention discloses a preparation method of modified welan gum, which comprises the step of reacting welan gum with citrate in the presence of an acidifier, a phase transfer catalyst and a reaction solvent to obtain the modified welan gum. The modified welan gum prepared by the method of the invention has the advantages of increasing the crosslinking performance, solving the problem of poor solubility of welan gum, obviously enhancing the viscosity of welan gum and increasing the viscosity compared with unmodified welan gum.
Description
Technical Field
The invention relates to a modification method of microbial polysaccharide, in particular to a preparation method of modified welan gum.
Background
Petroleum is a non-renewable energy source, and China has a huge demand on petroleum. However, the water content of the oil field in China basically enters the middle and later periods of exploitation, and the reduction of the permeability of an oil layer becomes a main problem in the oil exploitation. Fracturing and crack-making are common means for improving the permeability of an oil well, improving the oil extraction efficiency and increasing the yield. And water-based fracturing is a fracturing construction method which is the most mature in technology and the greatest in cost advantage. The traditional fracturing fluid takes guar gum as a thickening agent, the fluid preparation speed is slow, and the construction efficiency is low.
Welan gum is a high molecular polysaccharide polymer, generally prepared by taking corn starch as a raw material and performing microbial fermentation. The molecular structure of welan gum is similar to that of guar gum, and the welan gum has good thickening property, thermal stability, acid-base stability, salt resistance and the like. But the viscosity of the fracturing fluid is not high, the water solubility is low, and the dissolution speed is slow, so that the fracturing fluid is an important factor influencing the use of the fracturing fluid as a thickening agent.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the technical problems in the prior art, the invention provides a preparation method of modified welan gum.
The invention also aims to provide the modified welan gum prepared by the preparation method of the modified welan gum.
The technical scheme is as follows: the preparation method of the modified welan gum comprises the step of reacting welan gum with citrate in the presence of an acidifier, a phase transfer catalyst and a reaction solvent to obtain the modified welan gum.
The citrate is sodium salt or potassium salt of citric acid, preferably monosodium citrate or trisodium citrate dihydrate. The molar ratio of welan gum to citrate is 6: 7-3: 28, preferably 1: 1.2-3.5, and more preferably 1: 1.5-2.5.
The acidifying agent is hydrochloric acid, the concentration is 1-6 mol/L, and 1mol/L is preferable.
The phase transfer catalyst is a quaternary ammonium salt phase transfer catalyst, the quaternary ammonium salt phase transfer catalyst is preferably one or more of benzyltriethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride and trimethyloctadecylammonium chloride, and the trimethyloctadecylammonium chloride has the best suspension effect. The mass ratio of the welan gum to the phase transfer catalyst is (1-2) to 1, and the preferred mass ratio is 1 to 1.
The reaction solvent is one or more of aromatic hydrocarbon, halogen substituted aromatic hydrocarbon and water.
Preferably, the reaction solvent is one or more of benzene, toluene, xylene, chlorobenzene, dichlorobenzene and water, and more preferably toluene and water.
The reaction temperature is 80-120 ℃, and preferably 80 ℃. The reaction time is 6-12 h, preferably 6-8 h, and more preferably 6 h.
The reaction is carried out under the stirring condition, and the stirring speed is 450-550 rpm, preferably 500-550 rpm.
The reaction pressure was normal pressure.
Preferably, the preparation method of the modified welan gum comprises the following steps:
(1) firstly, adjusting the pH value of a citrate aqueous solution to 2-4 by using an acidifying agent to obtain an acidified citrate aqueous solution;
(2) and (2) forming a suspension of welan gum and a second reaction solvent through a phase transfer catalyst, and then adding the acidified citrate aqueous solution obtained in the step (1) into the suspension for reaction to obtain the modified welan gum.
And (2) adding the acidified citrate aqueous solution obtained in the step (1) into the suspension within 10-60 min, and then carrying out modification reaction under reaction conditions, so that the water solubility and viscosity of the finally obtained modified welan gum can be further improved.
In step (1), preferably, the pH of the aqueous citrate solution is first adjusted to 3 with an acidifying agent.
In the step (1), the concentration of the citrate aqueous solution is 0.02-0.07 g/mL, preferably 0.03-0.05 g/mL.
In the step (2), the second reaction solvent is one or more of benzene, toluene, xylene, chlorobenzene and dichlorobenzene, and toluene is preferred. The mass volume ratio of the welan gum to the second reaction solvent is 60-70g/L, and preferably 62.5 g/L. Accordingly, the first reaction solvent is water in step (1).
The post-treatment method of the reaction comprises the following steps: collecting reaction liquid, pouring the reaction liquid into an organic solvent in which the citrate modified welan gum is insoluble to separate out a product, performing suction filtration, drying and crushing to obtain the modified welan gum.
The citrate modified welan gum insoluble organic solvent is ethanol.
The drying temperature is 50-70 ℃, and preferably 60 ℃. The drying time is 12-30 h.
The modified welan gum prepared by the method is also within the protection scope of the invention.
The modifier used in the present invention is citrate.
The IR spectra of welan gum before and after modification are shown in fig. 1 and fig. 2, respectively. The carboxylation modification of welan gum is that-C (CH) is added on the basis of the original structure2COOH)2OH, this structure. At 3400cm-1The left and right are the peak of stretching vibration of-OH, and the obvious peak in figure 2 is strengthened, which shows that-OH is increased; the modified welan gum is 2400cm-1The left and right appear, corresponding to the asymmetric expansion of carboxyl on the citric acid, the molecular structure of the surface citric acid is added into the modified product; at 1600cm-1The stretching vibration peak of C ═ O is shown in the left and right, and the peak is clearly strengthened in fig. 2, indicating that C ═ O is increased.
Has the advantages that: the modified welan gum prepared by the method of the invention has the advantages of increasing the crosslinking performance, solving the problem of poor solubility of welan gum, obviously enhancing the viscosity of welan gum and increasing the viscosity compared with unmodified welan gum.
Drawings
FIG. 1 is a welan gum IR spectrum.
FIG. 2 is an IR spectrum of a modified welan gum of the present invention.
Detailed Description
In the following examples, the viscosity was measured as follows:
0.6g of the product was taken and dissolved in 100g of water to prepare a 0.6 wt% solution. The temperature of the thermostatic water bath is controlled at 25 ℃, and the viscosity of the thermostatic water bath is measured by a viscometer.
Example 1:
2.414g trisodium citrate dihydrate (8.208mmol, 3.04eq) is dissolved in 50mL water, and the pH is adjusted to about 3 by 1mol/L hydrochloric acid to prepare solution I; in a three-neck flask, 5g of welan gum (2.7mmo1) and 5g of trimethyloctadecyl ammonium chloride are mixed in 80ml of toluene under the condition of stirring to prepare 62.5g/L suspension, and the solution I is slowly added into the suspension and stirred at the rotating speed of 450rpm to be fully dissolved; reacting for 8h under the stirring conditions of normal pressure, 80 ℃ and 450rpm, taking out reaction liquid, pouring into a large amount of absolute ethyl alcohol to separate out a product, washing, filtering, and drying for 24h at 60 ℃ to obtain the modified welan gum product. The product was dissolved in 400mL of 2 wt% KCl solution over 2 h. The product was taken out and prepared as a 0.6 wt% aqueous solution, and the viscosity was 0.0494pa.s as measured using a six-speed rotational viscometer model ZNN-D6 at a rotational speed of 300 r/min.
Example 2:
dissolving 0.87g monosodium citrate (4.104mmol, 1.52eq) in 30mL water, and adjusting pH to about 3 with 1mol/L hydrochloric acid to prepare solution I; in a three-neck flask, 5g of welan gum (2.7mmol) and 5g of trimethyloctadecyl ammonium chloride are mixed in 80ml of toluene under the condition of stirring to prepare 62.5g/L suspension, the solution I is slowly added into the suspension, and the suspension is stirred at the rotating speed of 450rpm to be fully dissolved; reacting for 6h under the stirring conditions of normal pressure, 80 ℃ and 550rpm, taking out reaction liquid, pouring into a large amount of absolute ethyl alcohol to separate out a product, washing, filtering, and drying for 24h at 60 ℃ to obtain the modified welan gum product. The product was dissolved in 400mL of 2 wt% KC1 solution over 2 h. The product was taken out and prepared as a 0.6 wt% aqueous solution, and the viscosity was measured at 300r/min using a six-speed rotational viscometer model ZNN-D6 at 0.0532pa.s.
Example 3:
dissolving 1.39g (2.43eq) of monosodium citrate in 30mL of water, and adjusting the pH value to about 3 by using 1mol/L hydrochloric acid to prepare a solution I; in a three-neck flask, 5g of welan gum and 5g of trimethyloctadecyl ammonium chloride are mixed in 80ml of toluene under the stirring condition to prepare 62.5g/L suspension, the solution I is slowly added into the suspension, and the suspension is stirred at the rotating speed of 450rpm to be fully dissolved; reacting for 6h under the conditions of normal pressure, 80 ℃ and 500rpm stirring, taking out reaction liquid, pouring into a large amount of absolute ethyl alcohol to separate out a product, washing, filtering, and drying for 24h at 60 ℃ to obtain the modified welan gum product. The product was dissolved in 400mL of 2 wt% KCl solution over 2 h. The product was taken out and prepared as a 0.6 wt% aqueous solution, and the viscosity was 0.0535pa.s as measured using a six-speed rotational viscometer model ZNN-D6 at a rotational speed of 300 r/min.
Example 4:
as in example 1, the only difference is:
the phase transfer catalyst is benzyltriethylammonium chloride, and the mass ratio of the welan gum to the phase transfer catalyst is 1.5: 1. The reaction solvent is dimethylbenzene, and the mass volume ratio of welan gum to the reaction solvent is 60 g/L. The molar ratio of welan gum to citric acid is 6: 7. Citric acid was added to the suspension of welan gum and reaction solvent within 10 min. The reaction temperature is 120 ℃, and the reaction time is 12 h. Stirring at 500rpm to obtain modified welan gum.
Example 5:
as in example 1, the only difference is:
the phase transfer catalyst is tetrabutylammonium bromide, and the mass ratio of welan gum to the phase transfer catalyst is 2: 1. The reaction solvent is chlorobenzene, and the mass volume ratio of welan gum to the reaction solvent is 70 g/L. The molar ratio of welan gum to citric acid is 3: 28. Citric acid was added to the suspension of welan gum and reaction solvent within 60 min. The reaction stirring speed is 550rpm, and the modified welan gum product is prepared.
Comparative example 1:
the unmodified welan gum is dissolved in 400mL of 2 wt% KCl solution and can not be dissolved within 2 h. Unmodified welan gum is prepared into 0.6 weight percent aqueous solution, and the viscosity is 0.0415pa.s when the viscosity is measured by using an ZNN-D6 type six-speed rotary viscometer under the condition of the rotating speed of 300 r/min.
Claims (9)
1. A preparation method of modified welan gum is characterized in that welan gum and citrate react in the presence of an acidifier, a phase transfer catalyst and a reaction solvent to obtain the modified welan gum.
2. The method according to claim 1, wherein the citrate is a sodium salt or a potassium salt of citric acid, and the molar ratio of welan gum to citrate is 6:7 to 3: 28.
3. The method of claim 1, wherein the acidifying agent is hydrochloric acid.
4. The method according to claim 1, wherein the phase transfer catalyst is one or more of benzyltriethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride and trimethyloctadecylammonium chloride, and the mass ratio of welan gum to the phase transfer catalyst is (1-2): 1.
5. The method according to claim 1, wherein the reaction solvent is one or more of aromatic hydrocarbon, halogen-substituted aromatic hydrocarbon and water, the reaction temperature is 80-120 ℃, and the reaction time is 6-12 h.
6. The method of claim 1, wherein the reaction solvent is one or more of benzene, toluene, xylene, chlorobenzene, dichlorobenzene and water.
7. The method of claim 1, wherein the reaction is carried out under stirring conditions at a speed of 450 to 550 rpm.
8. The method of claim 1, comprising the steps of:
(1) firstly, adjusting the pH value of a citrate aqueous solution to 2-4 by using an acidifying agent to obtain an acidified citrate aqueous solution;
(2) and (2) forming a suspension of welan gum and a reaction solvent through a phase transfer catalyst, and then adding the acidified citrate aqueous solution obtained in the step (1) into the suspension for reaction to obtain the modified welan gum.
9. The method according to claim 8, wherein in the step (1), the concentration of the citrate aqueous solution is 0.02-0.07 g/mL.
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|---|---|---|---|---|
| CN103570844A (en) * | 2013-11-20 | 2014-02-12 | 南京工业大学 | Preparation method for carboxyethyl welan gum |
| CN104151443A (en) * | 2014-08-13 | 2014-11-19 | 南京工业大学 | Preparation method of modified welan gum |
| CN105586026A (en) * | 2015-07-28 | 2016-05-18 | 陕西太昱科技发展有限公司 | Biologically recyclable biogum oil well fracturing fluid and preparation method thereof |
| CN110498867A (en) * | 2018-05-17 | 2019-11-26 | 中国石油化工股份有限公司 | Modified welan gum and preparation method thereof and aqueous fracturing fluid composition and aqueous fracturing fluid |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2071711A1 (en) * | 1991-06-28 | 1992-12-29 | Todd Talashek | Enhanced solubility of welan gum in ethylene glycol |
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Patent Citations (4)
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|---|---|---|---|---|
| CN103570844A (en) * | 2013-11-20 | 2014-02-12 | 南京工业大学 | Preparation method for carboxyethyl welan gum |
| CN104151443A (en) * | 2014-08-13 | 2014-11-19 | 南京工业大学 | Preparation method of modified welan gum |
| CN105586026A (en) * | 2015-07-28 | 2016-05-18 | 陕西太昱科技发展有限公司 | Biologically recyclable biogum oil well fracturing fluid and preparation method thereof |
| CN110498867A (en) * | 2018-05-17 | 2019-11-26 | 中国石油化工股份有限公司 | Modified welan gum and preparation method thereof and aqueous fracturing fluid composition and aqueous fracturing fluid |
Non-Patent Citations (3)
| Title |
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| Optimal experimental conditions for Welan gum production by support vector regression and adaptive genetic algorithm;Li zhongwei等;《PLOS ONE》;20171009;第12卷(第10期);第1-15页 * |
| Two-step economical welan gum production by Sphingomonas sp. HT-1 from sugar industrial by-products;Xiaoliu Liu等;《Carbohydrate Polymers》;20180201;第181卷;第412-418页 * |
| 相转移催化法合成羟丙基瓜尔胶;熊蓉春等;《北京化工大学学报》;20051231;第32卷(第1期);第43-50页 * |
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