DE2549411A1 - PROCESS FOR PREPARING SPHERICAL SILICON DIOXIDE PARTICLES AND USE OF THE PARTICLES PRODUCED BY THIS PROCESS - Google Patents

Description

SHELL INTERNATIONAL RESEARCH MAATSCHAPPIJ B.V. The Hague, Netherlands

"Process for making spherical silica particles and use of those made by this process Particle ".

Priority: November 6, 1974, UK No. 47991/74

The invention relates to a method for producing spherical Silica particles with high water resistance and high breaking strength. The invention also relates to Use of the particles produced by this process.

Silica particles are used on a large scale e.g. as catalysts, Catalyst support materials, adsorbents, desiccants and ion exchangers are used. For most of the Above-mentioned uses are preferably spherical Particles of the same shape with high breaking strength

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used. A convenient way of making such particles is the well-known So1 gel process. According to this Process creates a silica hydrosol by mixing

/ with / an aqueous solution of an alkali metal silicate / an aqueous solution of an acid. The hydrosol is converted into droplet form and the droplets are gelled in a water-immiscible liquid. After reducing the alkali metal content of the spherical silica hydrogel particles in an aqueous medium to less than 1 percent by weight, based on the dry substance, the particles are dried and calcined.

The term "particles with high breaking strength" means in the present patent specification particles with a breaking strength

2
strength of at least 12 kg / cm. According to the sol-gel method, silica particles having such a high breaking strength are easily obtained. However, the particles produced by the above method are poor in water resistance. This is a serious disadvantage when the silica particles are to be used for applications in which they must be contacted with water, such as in the preparation of silica-based catalysts by impregnating the silica particles with an aqueous solution of compounds of catalytically active metals. When silicon dioxide particles with low water resistance come into contact with water, cracks or cracks occur in a considerable part of the particles or the partial

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to disintegrate.

The term "particles with high water resistance" in the present specification means particles with a Water resistance of at least 80 percent. The water resistance of the spherical silica particles is shown in determined by a standard test method in which 100 of the spherical Silica particles 5 minutes at room temperature with five times the volume of water of the volume of the 100 spherical Silica particles are contacted. Then the particles are examined to determine the amount of particles, that have cracks or have disintegrated. The water resistance of the spherical silica particles is expressed as the percentage expressed in terms of particles that have not been damaged on contact with water.

It has now been found that spherical silica particles having high water resistance can be produced according to the sol-gel process if at least 25 percent of the water contained in the silica hydrogel particles is removed from these particles by evaporation before their alkali metal content is reduced. It is extremely surprising that a water removal step at this point in the process leads to an improvement in the water resistance of the silicon dioxide particles obtained as the product ,, and. this all the ¹¹ ^ h * t as at this stage, a water removal

This is followed by a process stage carried out in an aqueous medium and

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since the manufacturing process already has a water removal stage as the last process stage. It has been found to be essential found that the water removal step is carried out prior to reducing the alkali metal content of the particles, and that the beneficial effect of this water removal step on the water resistance of the product silica particles is not adversely affected by the subsequent treatment of the particles in an aqueous medium.

The expression "water removal by evaporation" is used in the present specification to distinguish those according to the invention Water removal treatment used by other treatments that remove water from the silica hydrogels is separated as in the treatment of the silica hydrogel particles with an aqueous ammonia solution. It has been found that the latter treatment also improves the water resistance of the spherical silica particles obtained as the product, but not this sufficiently increased beyond the required 80 percent. A The serious disadvantage of this treatment, which makes it completely unsuitable for the present purpose, is that this treatment increases the breaking strength of the particles considerably

2 is reduced to values well below the required 12 kg / cm lie.

The invention accordingly relates to a process for the production of spherical silicon dioxide particles with high water resistance.

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ORIGINAL INSPECTED

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ability and high breaking strength, which is characterized in that it is carried out in the following process stages:

(a) mixing an aqueous solution of an alkali metal silicate with an aqueous solution of an acid to form a silica hydrosol;

(b) converting the hydrosol to droplet form;

(c) Gelling the droplets in a water immiscible Liquid;

(d) evaporating at least 25 percent of that in the hydrogel particles contained water;

(e) reducing the alkali metal content of the hydrogel particles in an aqueous medium to less than 1 percent by weight, based on the dry substance; and

(f) drying and calcining the spherical silica particles.

In addition to the possibility of producing spherical silicon dioxide particles with high water resistance by means of the sol-gel process leads to the introduction of the invention Water removal step leads to a cost saving, since the volumes of the materials are smaller in the subsequent process steps need to be handled.

In the process of the present invention, a silica hydrosol is first used prepared by mixing an aqueous solution of an alkali metal silicate with an aqueous solution of an acid.

ORIGINAL INSPECTED

This can be carried out particularly expediently by separately feeding the starting solution into a mixing chamber, in which the mixing of the solutions is carried out with stirring. The alkali metal silicate and the acid are sodium silicate and Sulfuric acid used particularly expediently. After the silica hydrosol is made, it becomes droplet form transferred and gelled in a liquid immiscible with water. This can be particularly expedient by introducing of the hydrosol through a small opening in the bottom of the mixing chamber into the upper end of a vertically arranged / filled with oil Pipe. Gelling takes place during the downward movement of the hydrosol droplets through the oil. At the Bottom of the tube can put the spherical hydrogel particles in water collected, e.g. separated from the water by filtration, with

/ Treatment in the /

Washed water and then subjected to the / water removal step will. However, it is also possible to carry out the water removal step in the same oil in which the gelation took place Has.

In the water removal step of the present invention, at least 25 and preferably at least 50 percent of that is in the hydrogel particles contained water removed from this by evaporation. This water removal step can be carried out in a number of ways For example, the water can be removed from the hydrogel particles by contacting the particles with a dry gas stream, such as with a stream of dry air, optionally at elevated temperatures. The water can also come from the hydro

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ORIGINAL INSPECTED

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gel particles by heating the particles at atmospheric pressure or be separated at reduced or increased pressures. Further, the water can be removed from the hydrogel particles by contacting the Particles with an inert liquid at temperatures above 100 ° C or by contacting the particles at elevated temperatures

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Ren be removed with steam or / or steam-containing gas stream. Examples of measures that may be expedient to remove at least 25 percent of the water contained in the hydrogel particles are used, are described below:

(a) Heat treating the hydrogel particles at temperatures of about 100 C at reduced pressures;

(b) heat treating the hydrogel particles at temperatures above

100 ° C in a stream of air;

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(c) Heat treating the hydrogel particles at temperatures / approx

100 C at reduced pressures and subsequent heat treatment the particles at temperatures of about 500 ° C in a stream of air;

(d) Contacting the hydrogel particles with a hydrocarbon at temperatures above 100 ° C;

(e) heat treating the hydrogel particles at temperatures above 100 C in an autoclave at autogenous pressures; and

(f) heating the hydrogel particles in a stream of air and steam.

After the water separation stage where at least 25 percent of the water contained in the hydrogel particles have been separated therefrom by evaporation, the alkali metal content becomes the

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ORIGINAL INSPECTED

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Hydrogel particles in an aqueous medium to less than 1 percent by weight, based on the weight of the dry material. This alkali metal removal can be particularly expedient by treating the hydrogel particles with an aqueous one Ammonium nitrate solution until the desired low level is reached Alkali metal content can be carried out.

Finally, the hydrogel particles are dried and calcined. The drying and calcining of the hydrogel particles can be accomplished, for example, by heating the particles to temperatures over a period of time from 100 to 200 ° C or 450 to 550 ° C.

If desired, a small amount of filler can be used in accordance with the invention can be added to the silica particles. The addition of a filler can be advantageous for a number of reasons. First can thereby reduce the porosity of the silicon dioxide particles obtained as a product to be influenced. In addition, in various uses of the silica particles, the presence of, e.g. Alumina filler may be beneficial. It is also possible reduce the manufacturing cost of the silica particles by blending an inexpensive filler. The addition of the filler to the silicon dioxide particles can be made particularly expedient by admixing the filler to the aqueous solution of the alkali metal silicate and / or to the aqueous solution of the acid from which the hydrosol is produced by mixing will. Examples of suitable fillers are kaolin, Montmoril.lonit, Bentonite, precipitated silicon dioxide fillers, aluminum oxides,

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Zeolites and amorphous precipitated silica-alumina.

Regarding the amount of filler that can be added to the silica particles prepared according to the present invention, has been found that the presence of a filler in the silica particles obtained as a product increases the breaking strength of the Particle decreases, and that this effect with increasing filler content the particle becomes stronger. However, since the sol-gel process usually results in spherical silica particles with very high breaking strength, plays a small degradation this breaking strength is irrelevant, and a filler-containing spherical silica particles that meet the requirements

changes of a breaking strength of at least 12 kg / cm by far can be easily manufactured, provided that they have a filler content of 25 percent or less the amount of silica present in hydrosol form from which the silica particles are made. Adding a larger amount of filler to the silica particles leads to the risk of silica particles being entrained

a breaking strength below 12 kg / cm, and is accordingly does not constitute a measure according to the invention.

The spherical silica particles made in accordance with the present invention can be used, for example, as catalysts, catalyst support materials, adsorbents, desiccants and ion exchangers will. In particular, they are suitable as support materials for one or more catalytically active metals-containing catalysts

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ORIGINAL INSPECTED

analyzers. Silica particles made in accordance with the invention Catalysts containing carrier material can be used in various processes in the chemical and petroleum industries will. The production of the catalysts can be carried out by means of any desired method for producing a support material containing catalysts, such as by impregnating the spherical silica particles with an aqueous, salts of the subject solution containing catalytically active metals and subsequent drying and calcining of the mixture obtained, be performed. In an advantageous method for producing these catalysts, the catalytically active metals applied to the carrier material in an early stage of the catalyst carrier material production, e.g. when the carrier material is still in hydrogel form. This not only influences the porosity of the catalyst obtained as a product Rather, this manufacturing process also offers the advantage that the additional, required after each impregnation Drying and calcination steps become superfluous.

Spherical silicon dioxide particles produced according to the invention are particularly suitable as support materials for catalysts, which are used for the hydrogenative demetallization of heavy hydrocarbon oils and for the epoxidation of olefinically unsaturated ones Compounds with an organic hydroperoxide can be used.

Hydrogen demetallizing of heavy hydrocarbon oils represents a well-known process in the petroleum industry

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ORIGINAL INSPECTED

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industry and is used, among other things, to reduce the metal content of heavy hydrocarbon oils used as a feed for catalytic treatment processes, such as for the hydrogenating Desulfurization, or catalytic conversion processes,

/ are / are used in the same way as for hydrocracking and catalytic cracking / demetallization results in a lengthening of the catalysts used in the subsequent treatment or conversion processes. Hydrogen demetallizing is carried out by contacting the heavy hydrocarbon oil at elevated temperatures and pressures and in the presence of hydrogen with a catalyst. For this purpose, catalysts containing one or more metals from the group consisting of nickel], cobalt, molybdenum, tungsten and vanadium on a silicon dioxide carrier material are preferably used. In particular, catalysts containing at least one metal from the group nickel and cobalt and at least one metal from the group molybdenum, tungsten and vanadium, such as the metal combinations nickel / vanadium, nickel / molybdenum and cobalt / molybdenum, are used on a silicon dioxide carrier material. Spherical silica particles produced according to the invention are preferably carrier materials used for the aforementioned catalysts.

The epoxidation of olefinically unsaturated compounds with an organic hydroperoxide is well known Process in the chemical industry represents and is used, among other things, for the production of propylene oxide and epichlorohydrin from propylene or allyl chloride is used. The epoxidation of olefinically un-

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ORIGINAL INSPECTED

saturated compounds with an organic hydroperoxide is preferably increased by contacting the reactants Temperatures and pressures carried out with a catalyst. The preferred organic hydroperoxide is ethylbenzene hydroperoxide is used because the methylphenylcarbinol obtained as a by-product in the reaction is easily valuable Styrene can be converted. Preferably at least one metal from the group molybdenum, tungsten, Titanium, zirconium and vanadium on a silicon dioxide carrier containing catalysts used. In particular, titanium is contained on a silicon dioxide carrier material Catalysts used for this purpose. Spherical silica particles prepared in accordance with the present invention are preferably support materials used for the aforementioned catalysts.

The examples illustrate the invention.

Comparative example A

An aqueous, 12 weight percent silica and a molar ratio of Na _? Sodium waterglass solution containing 0 / Si0 ₂ of 0.3 is continuously mixed in a mixing chamber with an aqueous, 1.2N sulfuric acid solution in a volume ratio of acid solution to waterglass solution of 0.75. After a residence time in the mixing chamber of a few seconds, the hydrosol obtained is converted into droplet form, and the hydrosol droplets are passed through a vertically arranged cylindrical tube with a length of

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ORIGINAL INSPECTED

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1.8 m fall that with a paraffinic hydrocarbon oil is filled with a temperature of 25 C. The droplets gel as they fall through the tube. The formed spherical Hydrogel particles are collected at the bottom of the tube in water at 25 ° C. After separating the spherical hydrogel particles they are washed with water by filtration. The water content of these spherical hydrogel particles is in one Standard test method determined, according to which a sample is heated from room temperature to 600 C within 3 hours and then is held at 600 ° C for one hour. The water content of the hydrogel particles is 90 percent by weight. The water content of the silica hydrogel particles in the examples below have each been determined using the standard test method described above.

Comparative example B

Part of the silica hydrogel particles with a water content of 90 percent by weight, which have been prepared according to Example A, is mixed with an aqueous 0.1 M ammonium nitrate solution treated at room temperature until the sodium content of the particles has fallen to 0.2 percent by weight, based on the dry substance is. After drying for 2 hours at 100 ° C. and for 3 hours Calcining at 500 C have the spherical shape obtained in this way Silica particles have a water resistance of 30 percent and a crush strength greater than 16.7 "kg / cm

2
(16.7 kg / cm is the maximum value that can be measured using the method used to determine the breaking strength of the particles.

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ORIGINAL INSPECTED

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example 1

A portion of the silica hydrogel particles prepared according to Example A. with a water content of 90 percent by weight is dried for 2 hours at 100 ° C under reduced pressure. To after this treatment the water content of the hydrogel particles is 18% by weight. Then the hydrogel particles with an aqueous ammonium nitrate solution and dried and dried in the same manner as the hydrogel particles in Example B calcined. The spherical silica particles thus obtained show a water resistance of 95 percent

2 and a breaking strength above 16.7 kg / cm.

Example 2

A portion of the silica hydrogel particles prepared according to Example A. with a water content of 90 percent by weight is dried for 3 hours at 120 C in a stream of air. After this Treatment, the water content of the hydrogel particles is 14 percent by weight. Then the Ilydrogelpartchen with an aqueous ammonium nitrate solution and dried and dried in the same manner as the hydrogel particles in Example B calcined. The spherical silica particles thus obtained had a water resistance of 93 percent and a breaking strength above 16.7 'kg / cm'.

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ORIGINAL INSPECTED

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Example 3

A portion of the silica hydrogel particles prepared according to Example A. with a water content of 90 percent by weight

Dried for 2 hours at 100 ° C under reduced pressure and then Calcined in a stream of air at 500 ° C. for 3 hours. After this treatment, the water content of the particles is

3 percent by weight. The particles then ground in the same way as in Example B with an aqueous ammonium nitrate solution treated, dried and calcined. The spherical silica particles thus obtained have a Water resistance of 95 percent and a breaking strength above 16.7 kg / cm.

Example 4

A portion of the silica hydrogel particles prepared according to Example A. with a water content of 90 percent by weight is with a paraffinic hydrocarbon oil at 150 C for 6 hours contacted. After this treatment, the particles have a water content of 12 percent by weight. Then the Particles in the same way as the hydrogel particles in Example B, treated with an aqueous ammonium nitrate solution,

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dries and calcined. The / silica pieces made in this way I have a water resistance of 96 percent

ο and a breaking strength above 16.7 kg / cm.

Example 5

Some of the silicon dioxide parts produced according to Example A

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ORIGINAL INSPECTED

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Chen with a water content of 90 percent by weight is heated to 185 ° C. in an autoclave at autogenous pressure for 1 1/2 hours. After this treatment, the water content of the hydrogel particles is 15 percent by weight. The hydrogel particles / like the hydrogel particles in Example B _{f are then} treated with an aqueous ammonium nitrate solution, dried and calcined. The spherical silica particles thus obtained had a water resistance of 94 percent and a

Breaking strength above 16.7 kg / cm.

Example 6

This example is carried out in practically the same way as Example 1, except that in the present case the aqueous Sodium water glass solution 12 g powdery kaolin filler per liter (which corresponds to 10 percent of the amount of silicon dioxide in the sol). The spherical silica particles obtained as the final product show a water resistance of 91 percent

and a breaking strength of 15 kg / cm.

Example7

A portion of the silica particles prepared according to Example A. With a water content of 90 percent by weight, the mixture is heated to 120 ° C. in an autoclave at autogenous pressure for 4 hours. After this treatment, the water content of the hydrogel particles is 60 percent by weight. Then the hydrogel particles, as described in Example B, treated with an aqueous ammonium nitrate solution, dried and calcined. That way

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ORIGINAL INSPECTED

spherical silica particles obtained have water resistance of 98 percent and a breaking strength of

2
above 16.7 kg / cm.

Comparative Example C

This example is performed in practically the same manner as Example 1 carried out, in the present case, however, the aqueous sodium waterglass solution contains 72 g of powdered kaolin filler each Liters (which corresponds to 60 percent of the amount of silica in the sol), The spherical silica particles obtained as the end product exhibit a water resistance of 85 percent and a

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Breaking strength of 10 kg / cm.

Comparative Example D.

A portion of the silica hydrogel particles prepared according to Example A. with a water content of 90 percent by weight is 16 hours at room temperature with an aqueous, 25 percent by weight Covered solution containing ammonia. After this treatment, the water content of the hydrogel particles is 30 percent by weight. The hydrogel particles are then, as described in Example B, with an aqueous ammonium nitrate solution treated, dried and calcined. The spherical silica particles thus obtained have water resistance of 45 percent and a breaking strength of 5 kg / cm.

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ORIGINAL INSPECTED

Comparative example E.

A portion of the silica particles prepared according to Example A. with a water content of 90 percent by weight is half an hour in an autoclave at an autogenous pressure of 120.degree heated. After this treatment, the water content of the hydrogel particles is 72 percent by weight. Then the Hydrogel particles as described in Example B, treated with an aqueous ammonium nitrate solution, dried and calcined. The spherical silica particles thus obtained have a water resistance of 50 percent and a

Breaking strength of 8 kg / cm.

Claims

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ORiQiNAL INSPECTED

Claims (11)

2 b 4 9 4 I! Claims 1. A method of producing spherical silica particles having high water resistance and high breaking strength, characterized in that it is carried out in the following process stages:. (a) mixing an aqueous solution of an alkali metal silicate with an aqueous solution of an acid to form a silica hydrosol; (b) converting the hydrosol to droplet form; (c) Gelling the droplets in a water immiscible Liquid; (d) evaporating at least 25 percent of that in the hydrogel particles contained water ;. (e) reducing the alkali metal content of the hydrogel particles in an aqueous medium to less than 1 percent by weight,
based on dry matter; and (f) drying and calcining the spherical silica particles. 2. The method according to claim 1, characterized in that in process step (d) at least 50 percent of that in the hydrogel particles contained water is removed by evaporation. 3. The method according to claim 1 or 2, characterized in that ORIGINAL INSPECTED that the water is separated from the hydrogel particles by contacting the particles with a dry gas stream. 4. The method according to claim 1 or 2, characterized in that the water is removed from the hydrogel particles by heating the particles is separated. 5. The method of claim 1 or 2, characterized in that the water is separated off from the hydrogel particles by contacting the particles with an inert liquid at temperatures above 100 ^0C. 6. The method according to claim 1 or 2, characterized in that that the water is removed from the hydrogel particles by contacting the particles at elevated temperatures with steam or a steam containing gas stream is separated. 7. The method according to claim 1 to 6, characterized in that an amount of filler of at most 25 percent of the amount of silicon dioxide is incorporated into the silica particles in the hydrosol from which the silica particles are made. 8. Use of the spherical prepared according to claim 1 to 7 Silica particles as a support material for catalysts containing one or more metals with catalytic activity. 0-3 820/1023 9. Embodiment according to claim 8, characterized in that that the silicon dioxide particles are used as a carrier material for catalysts, in their production the catalytically active metals have been applied to the support material in an early stage of the catalyst production. 10. Embodiment according to claim 8 and 9, characterized in that that the silica particles are used as a support material for catalysts for the hydrodemetallization of heavy hydrocarbon oils can be used in the heavy hydrocarbon oil at elevated temperatures and pressures and in the presence of hydrogen with at least one metal from the group consisting of nickel and cobalt and at least one metal from the group Molybdenum, tungsten and vanadium as catalytically active metals-containing catalyst is contacted. 11. Embodiment according to claim 8 and 9, characterized in that that the silicon dioxide particles as a carrier material for catalysts for the epoxidation of olefinically unsaturated compounds be used with an organic hydroperoxide, in which the reactants with a titanium as the catalytically active Metal containing catalyst are contacted. 609820/1023