RU2293057C2 - Method of production of hydrophobic silica - Google Patents

Abstract

FIELD: organic and physical chemistry; chemical modification of solid surfaces of highly dispersed amorphous silica for imparting hydrophobic properties; oil and gas industry; manufacture of building materials.

SUBSTANCE: proposed method consists in production of silica by chemical modification of surface with the aid of organic compounds at elevated temperature. Modification reaction is conducted in reactor at mechanical mixing and at boiling point of modifying agent. Modification of surface is performed with the aid of compound selected from group of higher α-olefins C₁₀-C₁₆ at elevated temperature; the procedure is continued for 3-10 h at the following ratio of mixture components, mass-%: α-olefin : dispersed silica (17-95) : (5-83), respectively. Proposed method may additionally include drying or dehydroxylation of silica at temperature of 120-300°C for 2 h.

EFFECT: avoidance of corrosion of equipment; enhanced ecological safety; low cost of final product.

2 cl, 1 tbl, 12 ex

Description

The invention relates to the field of organic and physical chemistry, and in particular to methods of chemical modification of hard surfaces of highly dispersed amorphous silicas to give them hydrophobic properties, and can be used in the oil and gas industry, in the production of building materials.

The use of chemically modified silicas (KHMK) with hydrophobic properties in the treatment of the bottom-hole formation zone allows to increase the filtration properties of the reservoir, ultimately leading to an increase in oil production. For products made of ceramics, wood, paper, fabric, metals, bricks, concrete and other building materials, the use of such silicas increases their resistance to external influences and improves operational characteristics. Hydrophobic CMCs can be used as fillers for rubbers and rubbers, thickeners for greases, components of adhesives, etc.

To give hydrophobic properties to amorphous silicas, numerous methods have been developed for modifying their surface using haloalkylsilanes of the formula Hal _4-n SiR _n .

A known method of producing a hydrophobic dispersion, including surface treatment of the initial silica with hydroxide or carbonate of sodium, potassium or ammonium and subsequent chemical modification on copper or brass gratings with steam of an organosilicon compound, in particular dimethyldichlorosilane at 70-120 ° C and a layer thickness of the material on the lattice of 0.5 -3 mm or a mixture of water vapor and organosilicon compounds in the ratio (1-5): 1 at 100-110 ° C / RF patent No. 2066297, IPC 7 C 01 B 33/18, publ. 09/10/1996 /.

A method for producing a hydrophobic dispersed material based on silicon dioxide or metal oxide is described, including activation of the surface of oxides with solid alkali metal carbonates, drying to a moisture content of not more than 1 wt.%, Modification with an organorganic compound of the general formula Cl _4-n SiR _n , where n = 1 -3, R = H, methyl-, ethyl-, Cl-methyl-, phenyl-, followed by further treatment with tetraalkoxysilane. Activation and modification is carried out at 20-200 ° C for 30-120 min / RF patent 2089499, IPC 7 C 01 B 33/18, C 09 C 1/28, 3/12, publ. 09/10/1997 /.

Closest to the claimed invention is a method for producing hydrophobic silica, comprising three stages:

1. preliminary hydroxylation of the starting silica with water vapor (hydromodule 0.05-1) at 105-110 ° C;

2. subsequent drying at 125-150 ° C to a residual moisture content of not more than 0.9-1 wt.%;

3. surface modification of hydroxylated silica with compounds of the general formula R _4-n SiR ′ _n , or R ′ ₄ Si, or R _4-n Si _nm Hal _m R " _nm , where n = 1-3; m = 1-2; R = H, methyl, ethyl, Cl-methyl, propyl, phenyl; R ′ = OCH ₃ , OC ₂ H ₅ ; Hal = Cl, Br, I; R "= vinyl, allyl, methoxy, ethoxy; in the presence of 0.5-1.5 wt.% volatile acids / Patent RF 2152967, cl. С 09 С 3/12, С 01 В 33/159, publ. 07/20/2000 /.

The disadvantages of this method and, in General, methods using chlorine-containing alkyl (alkoxy) silanes as modifiers are:

1. the allocation in the process of corrosive gaseous hydrogen chloride, destroying the equipment;

2. the need to include in the technological scheme of the process equipment for the capture and deactivation of gaseous hydrogen chloride;

3. the relatively high cost of modifying agents;

4. multi-stage process.

The objective of the present invention is to eliminate factors that lead to corrosive effects on equipment and environmental pollution, reduce the cost of the final product obtained by this method and simplify the process.

This problem is solved by a method of producing a hydrophobic material based on silica, including chemical surface modification with organic compounds at elevated temperatures. Moreover, the modification is carried out by a compound selected from the group of higher α-olefins C ₁₀ -C ₁₆ for 3-10 hours at a ratio of the components of the mixture, wt.%, Α-olefin: dispersed silica (17-95) :( 5-83) respectively. The method may further include drying or dehydroxylation of silica at 120-300 ° C for 2 hours.

Aerosil 200, 300 (GOST 14922-77), white soot BS-120 with an initial specific surface of 187 m ² / g, 293 m ² / g, 120 m ² / g, respectively, were used as the initial silica (Brief Chemical Encyclopedia. in "Soviet Encyclopedia", Moscow, v.4, p.732).

The α-olefins used for modification correspond to TU 38.402-69-76-89 (C ₈ -C ₁₀ ), TU 38.402-69-69-89 (C ₁₂ -C ₁₄ ), TU 38.402-69-73-89 (C ₁₆ -C ₁₈ ).

The modification reaction is carried out in a reactor with mechanical stirring and the boiling point of the modifying agent. If necessary, drying or dehydroxylation is carried out in the same reactor immediately before modification. After modification, the reaction mixture is a homogeneous transparent mass from a gel-like consistency to a viscosity of 50 mm ² / s with a content of modified silica of 7-99% wt. depending on the ratio of the starting components. The reaction mixture is well soluble in aromatic and aliphatic hydrocarbons.

Data on the conditions for the chemical modification of silicas by higher α-olefins and the achieved hydrophobicity are given in the table.

Examples of specific performance.

Example 1. In a thermostated reactor equipped with a stirrer, reflux condenser, thermometer load 12 g (12%) of Aerosil 200 and 88 g (88%) of α-olefin fraction With ₁₄ H ₂₄ . The temperature in the reactor was raised to a boiling point of α-olefin of 250 ° C. The reaction is carried out with stirring for 5 hours. The resulting ready-to-use product is discharged from the reactor. To study the composition, evaluate the hydrophobicity, and take the IR spectra, 20 g of the reaction mixture was precipitated with 100 ml of acetone, the precipitate was filtered off under vacuum and dried at 100 ° С for 2 hours. The carbon content of 31%.

In the IR spectrum of modified silica, bands of stretching vibrations of CH ₂ -, CH ₃ groups with a frequency of 2915 and 2975 cm ^-1 and a band of deformation vibrations of CH ₂ groups with a frequency of 1645 cm ^{-1 are} recorded. In the IR spectrum there are no bands of stretching vibrations of CH-groups of olefin with a frequency of 3020 cm ^-1 and stretching vibrations -С = С- with a frequency of 1650 cm ^-1 . These features of the IR spectrum, as well as a significant carbon content indicate that the adsorption process is completed by a thermally initiated polymerization reaction.

The hydrophobicity of modified silica, determined by two methods, was 98.9%; 99.6%.

Example 2. 40 g (40%) of Aerosil 200 is loaded into the reactor and heated to 120 ° C for 2 hours with slow stirring without circulating water in the refrigerator. Then, 60 g (60%) of the α-olefin C ₁₄ H ₂₈ are fed into the reactor, the heating is increased to the boiling point of the α-olefin 250 ° C and kept under stirring for 3 hours.

The resulting ready-to-use product is discharged from the reactor. To study the properties, 10 g of the product is precipitated with 100 ml of acetone, the precipitate is filtered off and dried at 100 ° C for 2 hours. The carbon content of 17% wt.

In the IR spectrum of modified silica, bands of stretching vibrations of CH ₂ -, CH ₃ groups with a frequency of 2915 and 2975 cm ^-1 and a band of deformation vibrations of CH ₂ groups with a frequency of 1645 cm ^{-1 are} recorded. In the IR spectrum there are no bands of stretching vibrations of CH-groups of olefin with a frequency of 3020 cm ^-1 and stretching vibrations -С = С- with a frequency of 1650 cm ^-1 . These features of the IR spectrum, as well as a significant carbon content indicate that the adsorption process is completed by a thermally initiated polymerization reaction.

The hydrophobicity of modified silica was 98.3% and 99.0%.

Example 3. 50 g of Aerosil 300 are loaded into the reactor and heated to 300 ° C. with slow stirring for 2 hours without circulating water in the refrigerator. Then, 50 g of the α-olefin C ₁₀ H ₂₀ are fed into the reactor, the heating is increased to the boiling temperature of the α-olefin 170 ° C, and it is kept under stirring for 7 hours. The resulting ready-to-use product is discharged from the reactor. To study the properties, 10 g of the product is precipitated with 100 ml of acetone, the precipitate is filtered off and dried at 100 ° C for 2 hours. The carbon content of 17% wt.

In the IR spectrum of modified silica, bands of stretching vibrations of CH ₂ -, CH ₃ groups with a frequency of 2915 and 2975 cm ^-1 and a band of deformation vibrations of CH ₂ groups with a frequency of 1645 cm ^{-1 are} recorded. In the IR spectrum there are no bands of stretching vibrations of CH-groups of olefin with a frequency of 3020 cm ^-1 and stretching vibrations -С = С- with a frequency of 1650 cm ^-1 . These features of the IR spectrum, as well as a significant carbon content indicate that the adsorption process is completed by a thermally initiated polymerization reaction.

The hydrophobicity of modified silica was 97.6% and 98.5%.

Examples 4-12 are carried out analogously to examples 1-3, varying the conditions in accordance with the claims.

To remove adsorbed moisture and activate the surface of silica, a series of experiments were carried out with silicas previously dried or dehydroxylated in the temperature range 120-300 ° C.

A study of the composition and structure of modified silica was carried out on samples isolated from the reaction mass by reprecipitation in warm acetone to remove excess α-olefin, followed by drying at 100 ° C for 2 hours.

The hydrophobization efficiency was evaluated as the ratio of the difference between the specific surfaces of the original and after hydrophobization to the original specific surface. The specific surface was determined by the adsorption of methyl red according to the method of Shapiro / Shapiro I., Kolthoff I.M. Studies on aging of precipitates and coprecipitation. Thermal aging of precipitated silica (silica gel) // J. Am. Chem. Soc, - 1950. - V.72. - P.776 /.

или

.In parallel, the efficiency of hydrophobization was determined by the method, including boiling in water of a sample of reprecipitated modified silica (m). For this, the hydrophobic product, forming an non-wettable suspension, is separated from the aqueous layer, dried and weighed (m ₂ ). The aqueous layer was evaporated and the residue was weighed (m ₁ ). The effectiveness of hydrophobization is determined by the formula:

or

.

Raman spectra were recorded on a Thermo Nicolet IR Fourier spectrometer.

From the results obtained, it is seen that the hydrophobization efficiency of silicas of various grades is high and amounts to 97.6-99.6%. Moreover, when using Aerosil 200, the hydrophobization efficiency does not depend on the preliminary drying of the initial silica. The hydrophobization process is a one-stage, waste-free, obtained modified silica can be used for various purposes without isolation from the reaction mixture, since the presence of an excess of a-olefins in the reaction mass only facilitates the combination of the modified silica with hydrophobizable material.

In addition, the cost of silica modified with alkylchlorosilanes is 500-580 rubles / kg. In this amount, the cost of silica is 190 rubles / kg, the remaining costs are mainly related to the cost of alkylchlorosilanes and the costs of maintaining quickly correlating equipment and the costs of environmental protection measures. The cost of the proposed modified silica, taking into account energy costs, is not more than 300 rubles / kg, since the cost of α-olefins is only 10-12 rubles / kg.

Table.
Reaction conditions and characterization of modified silica samples isolated from the reaction mass Experience number Composition,% wt. Surface preparation, ° C The reaction temperature, ° C Modification reaction time, hour The carbon content,% wt. Specific surface, after modification, m ² / g Hydrophobicity,% Hydrophobicity,% Amorphous silica α-olefin one. Aerosil 200 12 C ₁₄ H ₂₈
88 No drying 250 5 31 2 / 98.9 99.6 2. Aerosil 200 40 C ₁₄ H ₂₈
60 120 250 3 17 3 / 98.3 99.0 3. Aerosil 300 50 C ₁₀ H ₂₀
fifty 300 170 7 17 7 / 97.6 98.5 four. Aerosil 200
25 C ₁₂ H ₂₄
75 120 170 10 eighteen 4 / 97.8 98.5 5. Aerosil 200
5 C ₁₂ H ₂₄
95 No drying 220 6 twenty 3 / 98.3 99.0 6. Aerosil 200 10 C ₁₆ H ₃₂
90 No drying 280 5 29th 2 / 98.9 99.6 7. Aerosil 200 40 C ₁₄ H ₂₈
60 120 250 10 29th 2 / 98.9 99.5 8. Aerosil 300 83 C ₁₄ H ₂₈
17 300 250 9 fifteen 6/98 99,4 9. Aerosil 300
12 C ₁₆ H ₃₂
88 120 280 10 28 6/98 99.5 10. BS - 120
twenty C ₁₄ H ₂₈
80 120 250 6 26 2 / 98.3 99.0 eleven. BS - 120
10 C ₁₄ H ₂₈
90 300 250 8 25 2 / 98.3 99,2 12. BS - 120
35 C ₁₆ H ₃₂
75 300 280 5 32 2 / 98.3 99.6

Claims (2)

1. A method of producing a hydrophobic material based on silica, including chemical surface modification with organic compounds at elevated temperature, characterized in that the modification is carried out by a compound selected from the group of higher α-olefins C ₁₀ -C ₁₆ for 3-10 hours at a ratio of components mixtures, wt.%, α-olefin: dispersed silica (17-95) :( 5-83), respectively. 2. The method according to claim 1, characterized in that the initial silica is preliminarily dried or dehydroxylated at 120-300 ° C for 2 hours