Method of production of hydrophobic silica

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

 

The invention relates to the field of organic and physical chemistry, and in particular to methods of chemical modification of solid surfaces highly dispersed amorphous silica to impart hydrophobic properties and can be used in the oil and gas industry, production of construction materials.

The use of chemically modified silicas (KMK) with hydrophobic properties when processing bottom-hole zones can improve the filtration properties of the manifold, leading, ultimately, to increase oil production. In ceramics, wood, paper, fabric, metals, brick, concrete and other building materials the use of such silica increases their resistance to external influences and improves performance. Hydrophobic KMK can be used as fillers for rubbers and resins, thickeners greases, components, adhesives and so on.

To give amorphous silica hydrophobic properties developed numerous ways to modify the surface using haloalkylthio formula Hal4-nSiRn.

A method of obtaining a hydrophobic dispersion comprising the surface treatment of the source of silica, a hydroxide or carbonate of sodium, potassium or ammonium and subsequent chemical is massive modification on copper or brass grids ferry organosilicon compounds particularly clear when 70-120°and the thickness of the layer of material on the grid of 0.5-3 mm, or a mixture of water vapor and silicon compounds in the ratio of (1-5):1 at 100-110° /patent RF №2066297, IPC 7 01 33/18, publ. 10.09.1996/.

Describes a method for dispersed hydrophobic material based on silicon dioxide or a metal oxide, comprising activating the surface of the oxide solid carbonates of alkali metals, drying to a moisture content of not more than 1 wt.%, modification of ORGANOMETALLIC compound of the General formula Cl4-nSiRnwhere n=1-3, R=H, methyl-, ethyl-, Cl -, methyl-, phenyl-, with subsequent additional processing tetraalkoxysilane. Activation and modification is carried out at 20-200°C for 30-120 min/patent RF 2089499, IPC 7 01 33/18, 09 With 1/28, 3/12, publ. 10.09.1997/.

Closest to the claimed invention is a method of obtaining a hydrophobic silica, comprising three stages:

1. pre-hydroxylation of the original silica water vapor (water ratio of 0.05-1) at 105-110°C;

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

3. the surface modification gidrauxilirovannogo silica compounds of the General formula R4-nSiR′nor R′4Si, or R4-nSin-mHalmRn-mwhere n=1-3; m=1-2; R=H, methyl, ethyl, Cl-methyl, propyl, phenyl; ′ =Co3OS2H5; Hal=Cl, Br, I; R=vinyl, allyl, methoxy, ethoxy; in the presence of 0.5-1.5 wt.% volatile acids /Patent RF 2152967, CL 09 With 3/12, 01 33/159, publ. 20.07.2000/.

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

1. the selection process corrosive gaseous hydrogen chloride, destroying the equipment;

2. the need for inclusion in the technological scheme of the process equipment for purification and decontamination of gaseous hydrogen chloride;

3. the relatively high cost of modifying agents;

4. a multi-stage process.

The present invention is to eliminate the factors leading to the corrosive effect on equipment and pollution reduction obtained by this method of the final product and simplifying the process.

This task is solved by a method of obtaining a hydrophobic material based on silica, including chemical modification of the surface of the organic compounds at elevated temperatures. Moreover, the modification of the lead compound selected from the group of higher α-olefins C10-C16within 3-10 hours at the mixing ratio wt.%, α-olefin:disperse silica (17-95):(5-83) sootvetstvenno is. The method may further include drying or degidroksilirovanie silica at 120-300°within 2 hours.

As the source of silica used Aerosil 200, 300 (GOST 14922-77), white carbon BS-120 with the source specific surface 187 m2/g, 293 m2/g 120 m2/g respectively (concise encyclopedia of chemical. Publishing house "Soviet encyclopedia", Moscow, v.4, s).

Used to modify α-olefins meet THE 38.402-69-76-89 (C8-C10), THE 38.402-69-69-89 (C12-C14), THE 38.402-69-73-89 (C16-C18).

The modification reaction is carried out in a reactor with mechanical stirring and boiling point of the modifying agent. If necessary, drying or degidroksilirovanie carried out in the same reactor immediately before the modification. After modification, the reaction mixture is a clear, homogenous mass of gel-like consistency to a viscosity of 50 mm2with the content of the modified silica 7-99% wt. depending on the ratio of initial components. The reaction mixture is soluble in aromatic and aliphatic hydrocarbons.

Data on the chemical modification of silica highest α-olefins and achievable value of hydrophobicity in the table.

Examples of specific performance.

Example 1. In components of the new reactor, equipped with stirrer, reflux condenser, thermometer download 12g (12 %) of Aerosil 200 and 88 g (88 %) α-olefin fraction With14H24. The temperature in the reactor is raised to boiling point α-olefin 250°C. the Reaction is carried out at a stirring for 5 hours. The ready to use product is unloaded from the reactor. To investigate the composition, evaluation of hydrophobicity and removing the IR spectra of 20 g of the reaction mixture is precipitated with 100 ml of acetone, the precipitate is filtered off on a vacuum and dried at 100°C for 2 hours. The carbon content in the composition of 31%.

In the IR spectrum of the modified silica recorded the bands of stretching vibrations of CH2-, CH3groups frequency 2915 and 2975 cm-1and strip deformation vibrations of CH2groups with a frequency of 1645 cm-1. In the IR spectrum there are no bands of stretching vibrations of CH-groups of the olefin with the frequency 3020 cm-1and stretching vibrations of-C=C - C frequency 1650 cm-1. These features of the IR spectrum, as well as significant carbon indicate that the adsorption process is completed thermally initiated polymerization reaction.

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

Example 2. Charged to the reactor 40g (40%) of Aerosil 200 and under slow stirring and heated to 120°in the course is 2 hours without water circulation in the refrigerator. Then, the reactor serves 60 g (60%) α-olefin C14H28increase heat to boiling point α-olefin 250°C and maintained under stirring for 3 hours.

The ready to use product is unloaded from the reactor. To study the properties of 10 g of the product 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 the modified silica recorded the bands of stretching vibrations of CH2-, CH3groups frequency 2915 and 2975 cm-1and strip deformation vibrations of CH2groups with a frequency of 1645 cm-1. In the IR spectrum there are no bands of stretching vibrations of CH-groups of the olefin with the frequency 3020 cm-1and stretching vibrations of-C=C - C frequency 1650 cm-1. These features of the IR spectrum, as well as significant carbon indicate that the adsorption process is completed thermally initiated polymerization reaction.

The hydrophobicity of the modified silica was 98,3% 99,0%.

Example 3. Charged to the reactor 50 g of Aerosil 300 and, with slow stirring, heated to 300°C for 2 hours without water circulation in the refrigerator. Then, the reactor serves 50 g α-olefin With10H20increase heat to boiling point α-olefin 170°and incubated at paramasivan is 7 hours. The ready to use product is unloaded from the reactor. To study the properties of 10 g of the product 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 the modified silica recorded the bands of stretching vibrations of CH2-, CH3groups frequency 2915 and 2975 cm-1and strip deformation vibrations of CH2groups with a frequency of 1645 cm-1. In the IR spectrum there are no bands of stretching vibrations of CH-groups of the olefin with the frequency 3020 cm-1and stretching vibrations of-C=C - C frequency 1650 cm-1. These features of the IR spectrum, as well as significant carbon indicate that the adsorption process is completed thermally initiated polymerization reaction.

The hydrophobicity of the modified silica was $ 97.6% and 98.5 per cent.

Examples 4-12 carried out similarly to examples 1-3, varying conditions in accordance with the invention.

To remove the adsorbed moisture and activate the surface of the silica a series of experiments was performed with silica, previously subjected to drying, or degidroksilirovanie in the temperature range 120-300°C.

The study of the composition and structure of modified silica was performed on samples isolated from the reaction mass by presidenial in warm acetone d is I remove excess α -olefin, followed by drying at 100°within 2 hours.

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

In parallel, the efficiency of waterproofing was determined by the method involving boiling in water sample perezajennogo modified silica (m). This hydrophobic product, forming a resistant mist is separated from the aqueous layer, dried, and weighed (m2). The aqueous layer is evaporated and the residue is weighed (m1). The effectiveness of waterproofing is determined by the formula:or.

Raman spectra were shot on IR Fourier spectrometer Thermo Nicolet.

The results show that the effectiveness of hydrophobization of silica of different brands and high amounts of 97.6-99.6 percent. Moreover, when using Aerosil 200 effectiveness of waterproofing does not depend on pre-drying of the source of silica. The process of waterproofing single-stage, non-waste derived modified silica can be used for RA what personal goals without isolation from the reaction mixture, because the presence in the reaction mass excess of a-olefins only facilitates the combination of the modified silica with gidrofobizirovannym material.

In addition, the cost of silica modified by alkylchloro silane is 500-580 RUR/kg In the amount of the cost of the silica - 190 rubles/kg, other costs, primarily associated with the cost alkylchlorosilanes and maintenance costs quickly correlating equipment and the cost of environmental protection measures. The cost of the proposed modified silica with regard to energy consumption is not more than 300 rubles/kg, as the cost of α-olefins just 10-12 rubles/kg

/tr>
Table.

Reaction conditions and characterization of modified silica samples isolated from the reaction mass
no experienceComposition, % wt.Surface preparation, °CThe reaction temperature, °The reaction time of the modification, hThe carbon content, % wt.Specific surface, after modification, m2/g Hydrophobicity %Hydrophobicity %
Amorphous silicaα-olefin
1.Aerosil 200 12C14H28< / br>
88
Without drying2505312/98,999,6
2.Aerosil 200 40C14H28< / br>
60
1202503173/98,399,0
3.Aerosil 300 50C10H20< / br>
50
3001707177/97,698,5
4.Aerosil 200

25
With12H24< / br>
75
12017010184/97,898,5
5.Aerosil 200

5
C12H24< / br>
95
Without drying2206203/98,399,0
6.Aerosil 200 10With16H32< / br>
90
Without drying2805292/98,999,6
7.Aerosil 200 40C14H28< / br>
60
12025010292/98,999,5
8.Aerosil 300 83With14H28< / br>
17
3002509156/9899,4
9.Aerosil 300

12
With16H32< / br>
88
12028010286/9899,5
10.BS - 120

20
C14H28< / br>
80
1202506262/98,399,0
11.BS - 120

10
With14H28< / br>
90
3002508252/98,399,2
12.BS - 120

35
With16H32< / br>
75
3002805322/98,399,6

1. A method of obtaining a hydrophobic material based on silica, including chemical modification of the surface of the organic compounds at elevated temperature, characterized in that the modification of the lead compound selected from the group of higher α-olefins C10-C16within 3-10 hours at the mixing ratio wt.%, α-olefin: disperse silica (17-95):(5-83) are appropriate to estwenno.

2. The method according to claim 1, characterized in that the starting silica previously subjected to drying, or degidroksilirovanie when 120-300°C for 2 hours



 

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