DE2753393A1 - METHOD FOR INCREASING THE SPECIFIC MEDIUM PORE DIAMETER OF SILICON DIOXIDE - Google Patents

Description

SHELL INTERNATIONAL RESEARCH MAATSCHAPPIJ BV The Hague, The Netherlands

Process for increasing the specific mean pore diameter of silicon dioxide.

Claimed priority:

Dec. 02, 1976 - Netherlands - No. 7613413

The invention relates to a method for increasing the specific mean pore diameter of silicon dioxide.

Porous silica is widely used, among

as
other desiccant, catalyst, catalyst carrier and as an adsorbent in chromatographic separation. In each of these uses, the specific mean pore diameter of the silicon dioxide plays a more or less important role. In the present application, the specific mean pore diameter is referred to as ρ for the sake of brevity. For more information on ρ and how it is determined , see Dutch patent application no. 72 14 397

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showed in which this catalyst property in detail is described.

Occasionally the problem arises that a silicon dioxide, while being very suitable for a particular application, arises appears, for example, what properties such as particle size, total pore volume and mechanical strength is concerned, but the p-value of the silica is too small for the intended use. In some cases it was possible to eliminate this problem by subjecting the silica to a heat treatment, that is, that the silicon dioxide has been treated with liquid water and / or water vapor at an elevated temperature. For some types of silica this resulted in a considerable increase in size of p, while other properties of the silicon dioxides, such as chemical composition, total pore volume and mechanical strength, remained unchanged.

However, hydrothermal treatment has little or no hydrothermal treatment for a number of types of silica, for reasons not yet understood no effect on p. It has also been found that under certain temperature and pressure conditions the hydrothermal treatment causes a greater increase in ρ for some types of silica than for others. In this context it should be noted that when a silicon dioxide exhibits a significant increase in size due to hydrothermal treatment ρ shows that this generally increases if the conditions

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under which the treatment is carried out, that is, when a higher temperature and / or higher pressure is applied will.

Since the applicant is particularly concerned with the production of catalysts and catalyst supports, in particular for Hydrocarbon treatment processes, such as hydrated desulfurization and demetallization of residual oils, regularly faced with the above problems regarding the effect of hydrothermal treatment on ρ for silica saw, an in-depth investigation was carried out to gain a better understanding of the matter.

The investigation has shown that the effect of the hydrothermal treatment on ρ in the case of silicon dioxide can be considerably improved if the treatment is carried out in the presence of one or more added compounds of the elements Li, K, Na, Cs, Rb, Ca, Sr, Ba, of ! «^ - compounds and / or NH ₃ carries out.

In this context, an improved effect of the treatment after adding the aforementioned compounds is to be understood as that

a) a sufficient increase in ρ is achieved under conditions which, without such an addition, hardly or at all would not be given

b) under the same conditions the magnification of ρ is higher is as without this addition or

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c) under less severe conditions the same increase in ρ is achieved as without this addition.

The finding that the effect of hydrothermal treatment of silicon dioxide can thereby be significantly improved, that this treatment is carried out in the presence of one or more of the above-mentioned compounds becomes very essential believes that this finding broadens the usefulness of the treatment for increasing ρ of silica and, in principle, makes it possible to successfully apply this treatment to all types of silicon dioxide, as well as to any desired Enlargement of ρ can also be achieved under relatively mild conditions.

The present application accordingly relates to a process for increasing ρ of silicon dioxide, in which the silicon dioxide is subjected to a hydrothermal treatment in the presence of one or more added compounds of the elements Li, K, Na, Cs, Rb, Ca, Sr and Ba, of NH * Compounds and / or NH _{3 is} subjected.

In the process according to the invention, the silicon dioxide is subjected to a hydrothermal treatment. This treatment can generally be carried out in two ways, either by treating the silica with liquid water at an elevated temperature or by treating the silica with water vapor at an elevated temperature.

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The hydrothermal treatment of the silicon dioxide takes place with liquid water at elevated temperature, a treatment temperature between 50 and 374 C is generally chosen. The treatment temperatures are preferably between 100 and 350 ° C and especially between 150 ° C and 300 C. If a treatment temperature above 100 ° C is selected, then the treatment can be carried out in a closed vessel under autogenous pressure. The treatment times are generally between 15 minutes and 24 hours. The volume of liquid water is generally chosen so that the silica particles are perfect during the treatment are surrounded by water. When using treatment temperatures below 100 C it is sufficient if the volume of liquid water used substantially corresponds to the volume of the silica particles to be treated. This is also the case, though the treatment at a temperature above 100 ° C in a closed Vessel is made under autogenous pressure, provided that the volume of the closed vessel is equal to the volume of the silica particles to be treated. If the Treatment at a temperature above 100 ° C in a closed The vessel whose volume is considerably larger than that of the silica particles to be treated is a larger one Volume of liquid water required.

If the hydrothermal treatment of the silicon dioxide with water vapor takes place at an elevated temperature, the treatment

mean between 1
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temperature generally between 150 and 500 ° C. The water

partial steam pressure is preferably between 1 and 40 bar. Treatment times can be between 15 minutes and 24 hours. Treatment can either be done by that the silicon dioxide is brought into contact with a certain amount of water vapor in a closed vessel, or that water vapor is continuously passed over the silicon dioxide. In the latter case, a linear one is preferred Speed selected between 1 and 100 cm / hour.

In the process according to the invention, the silicon dioxide is subjected to a hydrothermal treatment in the presence of one or more added compounds of the elements Li, K, Na, Cs, Rb, Ca, Sr, Ba, NH compounds and / or NH ₃ . The way in which the compounds mentioned are added to the silicon dioxide depends on the type of hydrothermal treatment, that is to say whether liquid water or steam is used. If the hydrothermal treatment is carried out with liquid water, the compounds in question can in principle be added in two different ways. Once these compounds can be applied to the silicon dioxide before it is subjected to the hydrothermal treatment. The compounds in question are very advantageously applied to the silicon dioxide by impregnating the silicon dioxide with one or more of the compounds in question, then drying it and, if necessary, calcining it. A possible disadvantage in applying the compounds to the silica prior to hydrothermal treatment could be

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be that a certain proportion of the compounds used remains in the silica after the treatment, which is a could have an adverse effect on the behavior of the silica in subsequent use. A possibility, What is particularly thought of here is the presence of Na compounds in silicon dioxides necessary for use are provided as a catalyst carrier. If the hydrothermal treatment of the silicon dioxide is carried out with liquid water, so the respective compounds can be added in a very suitable manner that one for the hydrothermal Treatment used liquid water adds water-soluble compounds. Compared to the aforementioned impregnation method this method, in which the compounds used are dissolved in the water used for the treatment, has two advantages. First, it has been found that when the compounds are dissolved in the agent to be used for treatment Water considerably lower concentrations, based on the silicon dioxide to be treated, are sufficient to produce a comparable one Result in terms of an increase in ρ. It has also been found that when the connections are dissolved in the water to be used for the treatment of these compounds a much smaller proportion in the hydrothermally treated silica remains. If the hydrothermal treatment is carried out with via steam, the addition can be the connections in question are also made in two ways. Once the relevant connections can be accessed on the Silicon dioxide are applied before this the hydrother-

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paint is subjected to steam treatment. For this The same statements apply as you made above with regard to the impregnation in combination with hydrothermal treatment with liquid water. If the hydrothermal treatment of the silicon dioxide is carried out with water vapor, this can also be carried out in a very suitable manner with NH.-containing water vapor will. If the inventive method by means of a hydrothermal treatment is carried out in which the compounds in question are applied to the silicon dioxide in advance, then Na or K compounds are preferably chosen for this. If the inventive method carried out by means of a hydrothermal treatment, in which the respective compounds in the for the treatment to using water have been dissolved, then preferably Na, K or NH compounds are used for this purpose, with the particular preference is given to the NH compounds.

In all of the previously described embodiments of a hydrothermal treatment according to the invention, the relevant Compounds either incorporated into the silicon dioxide itself prior to the hydrothermal treatment or that of the hydrothermal

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len treatment used liquid water or steam added. However, the hydrothermal treatment according to the invention can also be used successfully by means of a combination of the two addition options be performed. For this purpose, the compounds in question are first applied to the silicon dioxide, and then the silica loaded in this way is at elevated temperature either with liquid water containing the compounds in question have been added or treated with steam containing NH3.

The amount of the compounds in question, which in the invention Procedures should also be used is essentially determined by the following six factors:

1) The increase in p sought after in the treatment;

2) the temperature used in the treatment;

3) The pressure used in the treatment?

4) The proportions present in the silica to be treated on K, Na and Ca;

5) the proportions of Al, Ti and Mg present in the silica to be treated;

6) The manner in which the compounds in question are added.

In general, it can be said that the influence of each of these factors, with the other five remaining constant, is such is that the amount of the compounds in question, which is added in the process according to the invention, the greater to select

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len is when

1) A greater increase in ρ is aimed for in the treatment will;

2) a lower temperature is used in the treatment;

3) a lower pressure is used in the treatment;

4) the proportions of K, Na and Ca present in the silicon dioxide to be treated are smaller and

5) the proportions of Al, Ti and Mg present in the silica to be treated are greater.

Regarding the influence of the type of addition of the compounds in question, it has already been pointed out that the Dissolving the same in the water to be used for the treatment a much smaller amount is sufficient than when the compounds have already been applied to the silicon dioxide beforehand by impregnation. Will the impregnation method applied, the amounts of the compounds in question, which are generally incorporated into the silicon dioxide must be so dimensioned in order to achieve the desired effect that the silicon dioxide to be treated is more than 0.1 g but does not contain more than 5 g of the active element per 100 g.

Once the type of hydrothermal treatment, the temperature and the pressure to be used have been determined for a specific silicon dioxide, the amounts of the compounds in question which must be used to obtain a specific p- I 809823/0748 can be determined

To achieve enlargement, determine by means of simple preliminary tests.

The process according to the invention is of very general importance for the enlargement of P in silicon dioxides. In particular, the process is of importance with regard to the production of silicon dioxide for use as catalysts and catalyst _{supports, in particular for hydrocarbon treatment processes (} such as hydrogenative desulfurization and the demetallization of residual oils.

The invention is explained in detail using the following example:

example

There were 21 different hydrothermal treatments (1 - 21) with two samples of silicon dioxide (I and II) and four samples of silicon dioxide (IA - ID), which are made from silicon dioxide I as the starting material were made. The silicon dioxide samples I and II had an Al content of 0.1 percent by weight, a total pore volume of 0.9 ml / g, a pressure

strength of over 16.7 kg / cm and were in spherical shape with a diameter of 1 - 3 mm. Silicon dioxide I had a p-value of 10 nm and an Na content of 0.1 percent by weight. .Silicon dioxide II had a p-value of 9.5 nm and an Na content of 0.7 percent by weight. The silicon dioxide samples IA, IB and IC were produced by impregnating three parts of silicon dioxide I with an aqueous Na ₃ CO ₃ -

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Solution, subsequent drying at 120 ° C. and calcination for two hours at 400 ° C. The silicon dioxides IA, IB and IC obtained in this way had Na contents of 0.2, 0.35 and 0.6 percent by weight, respectively. Silicon dioxide ID was prepared by impregnating part of silicon dioxide I with an aqueous one. Ca (NO ₃ ) ₂ ~ solution, subsequent drying at 120 ° C. and calcination for two hours at 400 ° C. The silicon dioxide ID obtained in this way had a calcium content of 2 percent by weight.

The different hydrothermal treatments were carried out in the following way:

Treatment 1

A mixture of 15 ml of silica and 19 ml of water was in heated in an autoclave at autogenous pressure to 200 ° C and then kept at this temperature for two hours.

Treatment 2

This treatment was carried out essentially as treatment 1, with the difference that in this case a temperature of 230 ° C. was used.

Treatment 3

15 ml of silicon dioxide were added to steam for one hour at a temperature of 280 ° C, a water vapor pressure of 10 bar and a linear speed of 10 cm / hour. loading

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acts.

Treatment 4

This treatment was carried out essentially as treatment 3, with the difference that in this case a temperature of 350 ° C. and a water vapor pressure of 40 bar are used became.

Treatment 5

This treatment was carried out essentially like treatment 3, with the difference that in this case a temperature of 200 ° C. and a water vapor pressure of 12.5 bar were used
became.

Treatments 6-10

A mixture of 15 ml of silicon dioxide and 19 ml of an aqueous one 2 χ 10 ~ molar Na_CO, solution was taking in an autoclave Autogenous pressure heated to a certain temperature and held at this temperature for two hours. The ones in the treatments 6-10 temperatures used were 190, 210, 225, 230 and 320 ° C, respectively.

Treatments 11-12

A mixture of 15 ml of silicon dioxide and 19 ml of an aqueous 10 'molar Na ₂ CO ₃ solution was heated to a certain temperature in an autoclave under autogenous pressure and then
Maintained at this temperature for two hours. The ones in the

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Treatments 11-13 were temperatures used, respectively 170, 200 and 230 ° C.

Treatments 14-16

A mixture of 15 ml of silica and 19 ml of an aqueous 5 χ 10 ~ molar Na-CO. Solution was taken in an autoclave autogenous pressure heated to a certain temperature and then kept at this temperature for two hours. The ones in the Treatments 14-16 temperatures used were 160, 190 and 230 ° C, respectively.

Treatment 17

A mixture of 15 ml of silicon dioxide and 19 ml of an aqueous 10 molar NaCl solution was heated to 230 ° C. in an autoclave under autogenous pressure and then heated for two hours kept this temperature.

Treatments 18-21

A mixture of 15 ml of silicon dioxide and 19 ml of an aqueous 2 × 10 molar solution of one of the following compounds was heated to 2 30 ° C. in an autoclave under autogenous pressure and then kept at this temperature for two hours. The compounds used in Treatments 18-21 were NaOH, Li ₃ CO ₃ , Cs ₂ CO _3, and NH ₄ OH, respectively.

The results of the investigation are shown in the table below. For the determination of ρ of the silicon dioxide

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the nitrogen adsorption / desorption method as well as the method described in Dutch patent application no. 72 14 397 ^e schrlebene be mercury penetration method is applied.

Tabel

attempt Silicon Hydrothermal ρ of the silica No. dioxide Treatment no. after the thermal No. Treatment in nm A. I. 1 14th B. II 1 115 C. I. 2 18th D. II 2 500 E. I. 3 18th F. II 3 120 G I. 4th 30th H II 4th 1350 1 IA 2 25th 2 IB 2 110 3 IC 2 160 J I. 5 15th 4th IA 5 26th 5 IB 5 45 6th IC 5 50 7th I. 6th 31 8th I. 7th 47 9 I. 8th 57 10 I. 9 65 11 I. 10 1200 12th I. 11 25th 1 3 / I. 12th 67 14th I. 13th 450 15th I. 14th 23 16 I. 15th 55 17th I. 16 950 18th I. 17th 75 19th I. 18th 65 20th I. 19th 85 21st I. 20th 95 22nd I. 21st 60 23 ID 9 950

Of the experiments listed in the table, only numbers 1-23 are experiments according to the invention. The experiments A-J

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are outside the teaching of the invention and are only used for comparison.

The following should be noted about the results listed in the table:

1) A comparison of experiments A, C, E and G with the experiments B, D, F and H each show that the effect of hydrothermal treatment on the p-value of silica increases with increasing natural Na content of the silica will. It has been found that this relationship applies to both hydrothermal treatment with liquid water as also applies to treatment with steam.

2) A comparison of experiments C, 1, 2 and 3 with one another and of experiments J, A, S and 6 with one another shows that the findings made under 1) also apply if the sodium content of the silicon dioxide was previously impregnated with a sodium compound has been raised.

3) A comparison of experiment 13 with experiment Ά and the experiments 10, 14 and 17-19 with experiment C shows that a hydrothermal Treatment with liquid water has a greater effect on the p-value of a silica when a sodium compound is in dissolved in the water. A comparison of experiments 20 - 22 with Experiment C shows that a similar result by solving

I a Li, Ca or NH ₄ compound in the water is obtained.

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4) A comparison of experiments 7-11, 12-14 and 15-19 with one another shows that a hydrothermal Treatment in which a sodium compound has been dissolved in the water has a greater effect on the p-value of a silica if the sodium compound is used in a higher concentration and the treatment contributes at a higher temperature.

5) A comparison of experiment 23 with experiment 10 shows that a hydrothermal treatment with liquid water in which a Na compound has been dissolved, has a greater effect on the p-value of a silica when the Ca content of the silica has been previously increased by impregnation with a Ca compound.

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Claims (11)

Claims 1. A method for increasing the specific mean pore diameter of silicon dioxide, characterized in that the silicon dioxide hydrothermal treatment in the presence of one or more added compounds of the elements Li, K, Na, Cs, Rb, Ca, Sr, Ba, of NH ^ - Compounds and / or NH _{3 is} subjected. 2. The method according to claim 1, characterized in that the hydrothermal treatment of the silicon dioxide at increased Temperature is carried out with liquid water. 3. The method according to claim 1, characterized in that the hydrothermal treatment of the silicon dioxide at elevated temperature carried out with steam. 4. The method according to claims 2 or 3, characterized in that that the compounds in question are applied to the silicon dioxide before this hydrothermal treatment is subjected. 5. The method according to claim 4, characterized in that the application of the compounds in question to the silicon dioxide by impregnating the same with one or more solutions of the compounds in question, then drying and optionally calcining takes place. 809823/0748 6. The method according to claims 4 or 5, characterized in that that sodium or potassium compounds are used. 7. The method according to claim 2, characterized in that the compounds in question for the hydrothermal treatment liquid water used can be added in the form of water-soluble compounds. 8. The method according to claim 7, characterized in that sodium, potassium or, preferably, NH compounds are used will. 9. The method according to claim 3, characterized in that IiH ₃ -containing steam is used. 10. The method according to claims 1-9, characterized in that the compounds in question on the silicon dioxide applied v / ground before this is subjected to the hydrothermal treatment, and that the hydrothermal treatment by treating the silica at elevated temperature either with liquid water containing the compounds in question have been added, or with NH, -containing steam. 11. Use of the silica treated according to claims 1-10 as a catalyst or catalyst support, ins- 809823/0748 especially for use in hydrocarbon treatment processes, such as hydrogenating desulphurisation and demetalli sization of residual oils. 809823/0748