WO1991017953A1

WO1991017953A1 - Simplified process for making expandable stratified silicates

Info

Publication number: WO1991017953A1
Application number: PCT/EP1991/000582
Authority: WO
Inventors: Britta Liesenfeld; Hans Dolhaine; Heinz Müller; Claus-Peter Herold; Stephan Von Tapavicza; Willi WÜST; Joseph Wollmann
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1990-05-17
Filing date: 1991-03-26
Publication date: 1991-11-28
Also published as: DE4015857A1; JPH05507054A

Abstract

The description relates to a simplified process for making expandable stratified silicates of the smectite type by the hydrothermal pressure treatment of mixtures and/or co-precipitates of the stratified silicate forming components in the presence of excess water and free bases. The novel process is distinguished in that a reaction mixture is placed in the hydrothermal reaction stage, the excess bases of which are made up at least partly of volatile organic amine compounds, the mineral solid phase formed is freed of the aqueous-basic part of the reaction mixture and, if necessary, residual parts of the organic amine compounds are evaporated out of the solid phase. The organic amine compounds are preferably primary, secondary and/or especially tertiary amines with a limited carbon content. It is also preferable to operate with at least preponderantly oxidic and/or hydroxidic reactants so that the reaction mixture is substantially free of non-volatile foreign components.

Description

"Simplified process for the production of swellable layered silicates (II)"

The invention relates to a simplified synthesis process for the production of water-swellable smectite clays and, in particular, describes a possibility in a simple manner to master the difficulties which arise in the production of highly swellable hectorites, saponites and / or saponite-hectorite hybrids.

The synthesis of phyllosilicates, especially hectorites, has been widely described in the literature (H. Strese and U. Hoffmann, Z. Aπorg. Allg. Chem. 247 (1941) 65-95; WI Grandquist and SS Pollack in " Clays and Clay Minerals "Natl. Acad. Sci., Natl. Res. Council Publ. 8 (1960) 150-169; DE-AS 1 667 502). A recent literature entry deals in detail with the knowledge available today on the structure, genesis and production of hectorite, cf. Karl-Heinz Bergk et al. Chem. Techn. 41 vol., Issue 6, 245-251.

Highly swellable layered silicates of the S ectit type (in particular hectorites, saponites and / or saponite-hectorite hybrids) are widely used, for. B. in the fields of cosmetics, paints, paints, wastewater treatment and rinsing liquids. The pronounced swelling capacity of the representatives of this class of compounds in water is used in almost all applications. The use of naturally occurring materials of the type concerned here often stands in the way of their limited purity, so that the synthesis of corresponding materials with predeterminable material properties is of great importance. In practice, hydrothermal synthesis at high temperatures is of paramount importance in practice. Details of the synthesis can be found in particular in the last-mentioned reference Karl-Heinz Bergk et al., Cf. here in particular the flow diagrams from Figures 3 and 4 on page 247 op

An industrially significant application area of highly swellable synthetic layered silicates of the type concerned here is their use as a viscosity-building agent in aqueous drilling fluid and borehole treatment agents in the exploration and development of deposits of, for example, petroleum and natural gas, but also in geothermal drilling, in water drilling, in the Execution of geoscientific drilling and drilling in the mining area. From the relevant literature, EP-A 260538 in particular should be mentioned here. The use of selected synthetic swellable layer silicates of the hectorite and / or saponite type for such water-based drilling fluid systems is described here. The last-mentioned literature reference describes in its example 1 a typical process for the production of the synthetic sheet silicates of the hectorite type to be used there. An aqueous suspension is prepared from magnesium sulfate, sodium hydroxide solution, sodium silicate solution and lithium carbonate, which is then reacted for about 4 hours at 180 ° C. in a stirred autoclave. The resulting product must then be filtered off from the mother liquor and the filter cake thus obtained must be washed with deionized water before the material is dried. These crucial steps of filtering a primarily formed hectorite slurry with subsequent washing of the separated solid phase are also integral components of the flow diagrams 3 and 4 from the literature reference Karl-Heinz Bergk et al. op. page 247 method shown. This filtering and washing is necessary to separate foreign constituents which are introduced into the reactor via the reactants and / or reaction aids used. tion raw mixture have been introduced. As a rule, these are water-soluble salts such as sodium sulfate, sodium carbonate or sodium chloride and the excess of free alkali used in the hydrothermal synthesis.

This apparently simple step of separating off the aqueous phase containing dissolved salts and then washing the synthetic smectite clay brings considerable difficulties for the practical process. This is immediately understandable from the following: the highly swellable layered silicate formed stubbornly holds at least portions of the aqueous reaction phase and requires special intensity for the subsequent cleaning by water washing. The economic efficiency of the overall process is unduly burdened by the processing steps mentioned here. This is where the object of the invention begins.

The invention has set itself the task of designing the known process for the production of synthetic and in particular highly swellable smectite clays in such a way that purification of the crude reaction product by filtration and subsequent washing no longer causes the previously known difficulties.

In a particular embodiment, the invention intends to make it possible to obtain high-purity smectite clays of a given structure and swellability by simply drying up the crude reaction product obtained primarily in the hydrothermal reaction, without intensive washing of the crude reaction product being necessary.

To achieve this object technically, the invention provides two main elements: the formation of the basic environment for the hydrothermal implementation, which acts as a reaction aid via the If smectite clay stoichiometrically required amount of alkali metal hydroxide is introduced into the reaction, certain bases will also be used if certain bases are used. In a preferred embodiment, the reactant mixture for the hydrothermal layered silicate-forming reaction should furthermore be free or practically free of those constituents which form non-volatile reaction by-products, in particular corresponding salts, in the course of the reaction.

The invention accordingly relates to a process for the production of swellable sheet silicates of the smectite type by hydrothermal pressure treatment of mixtures and / or coprecipitates of the sheet silicate-forming components in the presence of an excess of water and free bases. The new process is characterized in that a reaction mixture is introduced into the hydrothermal reaction stage, the base excess of which is at least partially and preferably at least predominantly formed by driftable organic amine compounds, that the mineral solid phase formed is made up of the aqueous-basic portion frees the reaction mixture and, if desired, drives off residual portions of the organic amine compounds from the solid phase.

The strippable bases used according to the invention are, in particular, sufficiently volatile organic amine compounds. Here, primary, secondary and / or tertiary amines and in particular corresponding unsubstituted aliphatic amines are the preferred reaction auxiliaries. The last-mentioned tertiary amines can be particularly suitable auxiliaries for adjusting the basic reaction environment. According to the invention, liquid amines in particular are used with sufficient volatility used that their separation from the crude reaction product via the gas phase together with the aqueous reaction medium and / or separated therefrom is possible without particular difficulty. Corresponding amines contain, for example, up to about 20 C atoms, preferably up to about 15 C atoms in the molecule. Amines with up to about 10 carbon atoms in the molecule can be of particular importance. Lower aliphatic amines, each having 2 to 6 carbon atoms in the alkyl radical, are of particular importance in the course of the inventive step. Lower tertiary aliphatic amines with, for example, 2 to 4 carbon atoms in each of the alkyl radicals are preferred auxiliaries for the purposes of the action according to the invention.

In an important embodiment, reaction mixtures containing at least predominantly oxidic and / or hydroxide reactants are used as the starting material for the hydrothermal reaction. These mixtures are essentially free of non-volatile foreign components, i. H. the amount of the non-volatile foreign matter is not more than 5% by weight, preferably not more than 1% by weight. The feed mixtures contain, as volatile mixture components, the water required for hydrothermal synthesis and the volatile bases for setting the basic reaction environment.

Highly swellable smectite clays of the type concerned according to the invention contain sodium in their layer lattice as alkali metal components and optionally at most approximately equal proportions of lithium, which are incorporated in oxidic form. In the conventional synthesis of such sheet silicates, as described, for example, in EP-A 260538 cited at the beginning, the sodium hydroxide is used in excess. This is necessary for two reasons: If salts are used in the layered silicate synthesis - For example, of the type of magnesium chloride and / or lithium carbonate - introduced, the acid components of these salts equivalent amounts of sodium hydroxide are required to form the appropriate neutral salts to be water-soluble and finally separated from the layered silicate. On the other hand, by setting the excess sodium hydroxide during the synthesis stage, the basic environment of the reaction mixture and thus the formation of a highly swellable layered silicate clay with a pronounced crystal structure should be guaranteed.

In contrast, the process according to the invention proposes a novel way: the base excess of the reaction mixture required in the stated sense should not be formed by sodium hydroxide as before, but by the use of selected organic amine compounds, as previously defined. This makes an independent and previously unknown process of the synthesis accessible:

Within the framework of the known conditions of hydrothermal synthesis, a highly crystalline layered silicate material forms as the primary reaction product, but initially has only limited swellability in the aqueous reaction phase. As a rule, the primary reaction products in the process of the invention are suspensions of a non-or only slightly swollen, finely divided sheet silicate of the desired formula, which is separated from the accompanying liquid phase by simple separation operations, in particular by filtration, and, if desired, also further cleaning operations. in particular can be subjected to a water wash. The sheet silicate isolated and purified in this way shows the presence of Nitrogen, although the bound base amounts in the

Are usually very low. By means of a suitable aftertreatment, preferably an aqueous-thermal treatment, these small bound proportions of the basic amine compounds used in the synthesis can be driven off. The extent to which the amine compounds are stripped off converts the swelling capacity of the layered silicate formed, and ultimately the desired highly swellable mineral material is formed. To facilitate the stripping off of the basic amine compounds, the use of very limited amounts of free alkali metal hydroxide and in particular sodium hydroxide can be advantageous. Accordingly, in a preferred embodiment, the process according to the invention provides that a primarily formed mineral solid phase of limited swellability is separated from the aqueous-basic portion of the reaction mixture by phase separation, in particular by filtration, if desired the washed mineral material is washed and the amine residue 1 by means of a stronger base, in particular by means of aqueous alkali hydroxide. The treatment of the primary mineral material with limited swellability and its residual proportion of bound organic amine bases is preferably carried out at elevated temperatures, for example in the temperature range around 100 ° C., in particular in the temperature range from about 60 to 150 ° C. In a preferred embodiment, the process is carried out at normal pressure or even at slightly reduced pressures in order to promote the stripping of the organic amine compounds. They can be separated off by distillation, in a particular embodiment of the process according to the invention the removal of these residual amine portions is combined with the drying of the swellable layered silicate now formed. But steaming out with superheated steam can also be an effective measure in In terms of the final cleaning and formation of the desired swelling assets. Here too, alkali hydroxide, in particular aqueous NaOH, is preferably introduced beforehand and / or simultaneously into the layered silicate product. In order to adjust the fully developed swellability of the product, alkali hydroxide amounts are generally required which correspond at least approximately to the ion exchange capacity of the respective layered silicate. In terms of quantity, these are very small amounts. For example, about 1 to 1.3 mmol of NaOH per g of layered silicate correspond to the stoichiometric amount required for amine exchange on hectorites. Accordingly, it is preferred according to the invention to use the alkali metal hydroxide to drive off the amine in this amount range, it being preferred to work with 2-3 times the amount of the stoichiometrically required amount.

The intermediate formation of a primary mineral reaction product of the required type, but with only limited swellability, can result in considerable simplifications in the purification of defined, highly swellable materials. The accompanying reaction products which are also formed, for example sodium chloride and / or sodium carbonate, can be freed from the primary reaction product without any practical difficulties in washing the primary reaction product obtained. The very limited proportions of the abortable amine compounds, which are retained in the primary reaction product and limit its swellability at this stage, can then be easily removed from the mineral material in the described manner in a secondary processing step and thus separated off. The process according to the invention is of particular importance for the production of synthetic swellable sheet silicates, as described in EP-A 260 538 and are accordingly characterized by the following general formula (I)

MgO. aMA. bAl2θ3. cSiθ2. nH2θ (I)

in the mean

M = Na ⁺ and / or Li ⁺ with a Na / Li ratio equal to or greater

1

A = F-, OH "and / or 1/20 ^2_ as well as a, b, c and n numbers are according to a = 0.1 to 0.6 b = 0 to 0.3 c = 1.2 to 1.7 n = 0 to 3.0.

In the approach for hydrothermal synthesis, in the preferred embodiment described above, the reactants containing magnesium, aluminum and silicon are introduced as oxidic and / or hydroxide reaction components. The same applies to sodium and possibly lithium, unless the fluoride ion has to be introduced here. Mixed compounds, such as sodium silicate and / or sodium aluminate, can be added to the reaction mixture in a manner known per se. It is essential for the invention in this preferred embodiment that the use of disruptive amounts of foreign constituents, such as are introduced into the reaction mixture, for example when magnesium salts are used, for example of the type of magnesium sulfate or magnesium chloride, and thus is dispensed with the subsequent separation and purification of the crude reaction product.

After the hydrothermal reaction phase has ended and the residual portions of the basic amine compounds have been driven off, the swellable layered silicates formed can be freed of residual water by simple drying. This drying can be carried out at normal pressure and / or at reduced pressure and can be accelerated by using elevated temperatures. The portions of the reaction mixture which are driven off via the vapor phase can, if desired, be condensed and used in whole or in part in circulation for further reaction mixtures. The drying of the product and / or the removal of the free volatile base can take place, for example, at temperatures up to 300 ° C., preferably in the range between 50 and approximately 250 ° C., with particular temperatures in the range from approximately 80 to 180 ° C. Significance can come.

As already stated, not only the water, but in particular also the residues of the volatile basic compound used for controlling the reaction can be driven off with this drying stage in the process according to the invention. This process step can be carried out in one or more stages in the sense of a joint removal of water and volatile base or a gradual separation of these volatile reaction aids.

In some cases, however, it has proven to be expedient to subject the reaction product formed to a time-limited thermal treatment in this final drying stage. The previously specified temperature areas are measures for suitable working conditions. It may be particularly expedient to carry out such a final temperature treatment - with simultaneous expulsion of remaining portions of water and / or volatile base - in the temperature range from about 100 to 150 ° C.

The time period for such a final drying and / or temperature treatment results primarily from the time period required to drive off the volatile constituents. In general, this period will not exceed 1 to 2 hours. The temperature treatment can be in the range of a few minutes, i.e. H. for example 5 minutes to about 45 minutes.

The solid reaction product obtained is expediently ground into a fine powder. All suitable grinding devices, for example toothed disk mills, are suitable for this.

To carry out the basic reaction under the conditions of hydrothermal synthesis in detail, the extensive information of the referenced prior art applies, provided that they do not conflict with the teaching of the invention. Thus, in the preferred embodiment, magnesium hydroxide or magnesium oxide can be used as the magnesium-containing compound; in particular, amorphous silicic acid, for example precipitated silicic acid, diatomaceous earth, but also proportionally but also water glass can be used as the silicon-containing compound, with the proviso that the content registered at the same time of sodium hydroxide does not or does not significantly exceed the stoichiometrically desired proportion. Aluminum hydroxide, so-called aluminum moist hydrate or aluminate lye can be used as the aluminum-containing compound, taking into account the restriction given previously for the water glass. A suitable one lithium-containing compound is, for example, lithium hydroxide. If fluoride ions are to be introduced into the reaction product, appropriate proportions of sodium and / or lithium fluoride are particularly suitable.

The amount of the abradable amine base to be used in each case can be in a relatively wide range and - based on the magnesium oxide present in the reaction mixture - can be, for example, in the range from 0.1 to 5 mol of the base per mol of magnesium oxide. It will generally be preferred to limit the amount of this basic component as much as possible, so that preferred addition amounts of the base to the reaction mixture for the hydrothermal reaction are in the range of about 0.2 to 2 moles of the amine base per mole of magnesium oxide in the reaction mixture lie.

The information in the prior art also applies to the choice of the process parameters of the hydrothermal reaction. Accordingly, the reaction is carried out in particular under the autogenous pressure of the reaction mixture at process temperature. The process temperatures in particular are the ranges from approximately 150 to 300 ° C., advantageously from approximately 200 to 270 ° C. The reaction time is in the range of 1 to 100 hours, preferably between about 1 and 20 hours. The reaction has usually progressed to such an extent after about 2 to 8 hours that the workup can be carried out in the sense of the drying treatment according to the invention.

The solids contents during the hydrothermal reaction phase are in the usual range. For example, the solids content can be increased by up to about 40% (mass fraction) in the aqueous / basic reaction mixture. However, preference is given to worked lower solids contents, which is in the range up to about 15% (mass fractions) and in particular below about 10% (mass fractions). In detail cf. the details of the cited printed prior art, for example in Karl-Heinz Bergk et al. aaO Also in the final aqueous-thermal treatment to drive off the amine residues with formation of the highly swellable nature of the mineral phase, corresponding mixing ratios are preferred.

In further refinements, the invention relates to the swellable smectite clays produced by the process according to the invention and to their use in particular in the context of water-based drilling fluid systems, as described in detail in EP-A 260 538.

B e i s p i e l e

example 1

To carry out the hydrothermal synthesis in a reaction autoclave, the reactants specified below are combined:

41.1 g MgO, 98% 3.9 g LiOH, 98% 77.5 g sodium water glass 37/40 (HENKEL company, Si02 molar ratio

: Na2Ö = 3.46: 1, total solids 34.9% by weight) 73.8 g precipitated silica FK 320 (DEGUSSA company) 204.4 g triethylamine, 99% 2104.0 g distilled water

The mixture of reactants in this approach corresponds to the following molar ratios:

1 MgO: 1.5 SiO 2: 0.08 L12O: 0.1 a2 O: 2 ^ 5) 3 ^ 120 H ₂ 0

The details are as follows:

Magnesium oxide was suspended in approx. 1700 g of water on the Pendraulik stirrer, lithium hydroxide was dissolved in it and the mixture of water glass, approx. 400 g of water and precipitated silica was added. After stirring for 5 minutes, the suspension is added to the autoclave, into which the amine was added after sealing.

Crystallization conditions: 4 hours at 250 ° C. The cooled suspension is divided into a plurality of partial amounts. A first portion is dried in the convection oven at 120 ° C and ground without the addition of sodium hydroxide solution. In further batches, sodium hydroxide solution is added to the respective suspension sample in different amounts. The respective

The mixture is stirred vigorously for 2 minutes and then dried in a convection oven at 120 ° C and ground.

The X-ray diffraction analysis of the primary reaction product shows a well-defined crystalline nature. From the individual dried and ground material samples

2.5% suspensions made in distilled water. Their viscosity is determined after 24 hours. The viscosity values of the individual samples are summarized below.

The table shows that the formation of the swellability in the aftertreatment with about 1 mmol NaOH / g layered silicate sets in clearly and under the specified test conditions when using twice the amount of NaOH with 6.7 Pas a qualitatively and quantitatively high-quality result is achieved. These two last defined numerical values for the additional amount of sodium hydroxide solution correspond to approximately 1-2 times the stoichiometric amount of the ion exchange capacity of the layered silicate formed.

Example 2

The following reaction batch is subjected to the hydrothermal reaction in the pressure vessel at 22 bar and 193 ° C. for 6 hours:

92.7 g sodium water glass 37/40 (HENKEL) 88.3 g precipitated silica FK 320 (DEGUSSA) 2516.6 g demineralized water 244.7 g triethylamine, 99% 8.6 g LiOH, 56% 49, 2 g MgO, tech.

The solid suspension obtained can be filtered comparatively effectively on the Seitz filter. The following details apply here:

Pressure: 1 bar

Filter paper: gray tape, 7.4 microns

Filtration time: the first 5 min. 380 ml then approx. 20 ml in 25

Min. Weighing filter cake: 350 g Weighing filtrate: 352 g

The conversion of the highly crystalline primary product by treatment with NaOH in the sense of the information in Example 1 leads to a highly swellable synthetic sheet silicate.

Claims

Patent claims

1. A process for the production of swellable layered silicates of the smectite type by hydrothermal pressure treatment of mixtures and / or coprecipitates of the layered silicate-forming components in the presence of an excess of water and free bases, characterized in that one in the hydrothermal reaction stage Introduces the reaction mixture, whose base excess is at least partially and preferably at least predominantly formed by abradable organic amine compounds, that the mineral solid phase formed is freed from the aqueous-basic portion of the reaction mixture and, if desired, residual portions of the organic amine compounds from the solid phase drives out.

2. The method according to claim 1, characterized in that primary, secondary and / or in particular tertiary amines with preferably up to 15 carbon atoms in the molecule, in particular with up to 10 carbon atoms in the molecule, are used as drivable amine compounds.

3. Process according to Claims 1 and 2, characterized in that a primarily formed mineral solid phase with limited swelling capacity is separated from the aqueous-basic portion of the reaction mixture by phase separation, in particular filtration, washed if desired and the residual amine portion is non-volatile , preferably stronger base, in particular alkali hydroxide, with the use of sodium hydroxide being preferred.

4. Process according to Claims 1 to 3, characterized in that the remaining portion of the organic base by treating the aqueous / mineral slurry at elevated temperatures, preferably with the use of aqueous sodium hydroxide, for. B. in the temperature range from about 60 to 150 ° C and preferably separated by distillation from the mineral solid, wherein the amount of the non-volatile base preferably corresponds at least approximately to the stoichiometric ion exchange capacity of the layered silicate formed.

5. Process according to Claims 1 to 4, characterized in that the removal of the amine residues is combined with the drying of the swellable layered silicate.

6. Process according to Claims 1 to 5, characterized in that a reaction mixture containing at least predominantly oxidic and / or hydroxide reactants, which is essentially free of non-volatile foreign substances, is introduced into the hydrothermal reaction.

7. The method according to claims 1 to 6, characterized in that, in the presence of substantially volatile components in the crude reaction mixture, at least on an intensive washing of the raw reaction product.

8. Process according to Claims 1 to 7, characterized in that the sheet silicates are freed from water and / or basic components or their remaining quantities by drying, preferably at normal pressure and / or reduced pressures, and, if appropriate, a finely powdered solid product after comminution wins, being Drying temperatures up to about 300 ° C, preferably those in the range of 50 to 250 ° C may be preferred.

9. Process according to Claims 1 to 8, characterized in that synthetic swellable sheet silicates of the following general formula (I) are prepared

MgO. aMA. bAl2θ3. cSiθ2 • nH ₂ 0 (I)

in the mean

M = Na ⁺ and / or Li ⁺ with a Na / Li ratio equal to or greater than 1

A = F-, OH "and / or.1 / 20 ² " as well as a, b, c and n numbers are according to a = 0.1 to 0.6 b = 0 to 0.3 c = 1.2 to 1 , 7 n - 0 to 3.0.

10. The method according to claims 1 to 9, characterized in that one carries out the hydrothermal reaction at the autogenous pressure of the reaction system under reaction conditions.

11. The method according to claims 1 to 10, characterized in that the hydrothermal reaction at temperatures of about 150 to 300 ° C, preferably from about 200 to 270 ° C with reaction times between 1 and 20 hours, preferably between 2 and 8 Hours.

12. The method according to claims 1 to 11, characterized in that the volatile bases in amounts of 0.1 to 5 mol, preferably in amounts of 0.2 to 2 moles, based in each case on moles of magnesium oxide in the reaction mixture.