CA1179477A - Process for the controlled production of silica by means of flame hydrolysis - Google Patents
Process for the controlled production of silica by means of flame hydrolysisInfo
- Publication number
- CA1179477A CA1179477A CA000344998A CA344998A CA1179477A CA 1179477 A CA1179477 A CA 1179477A CA 000344998 A CA000344998 A CA 000344998A CA 344998 A CA344998 A CA 344998A CA 1179477 A CA1179477 A CA 1179477A
- Authority
- CA
- Canada
- Prior art keywords
- water vapour
- flame hydrolysis
- silica
- flame
- fed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
- C01B33/181—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by a dry process
- C01B33/183—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof by a dry process by oxidation or hydrolysis in the vapour phase of silicon compounds such as halides, trichlorosilane, monosilane
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/22—Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention provides a process for the con-trolled production of silica by means of flame hydrolysis in which the thickening effect can be adjusted independently of the BET surface area of the silica obtained. This is attained by introducing additional water vapour either into the reaction mix-ture or into the reaction flame.
The present invention provides a process for the con-trolled production of silica by means of flame hydrolysis in which the thickening effect can be adjusted independently of the BET surface area of the silica obtained. This is attained by introducing additional water vapour either into the reaction mix-ture or into the reaction flame.
Description
7~
" , , The present invention relates to the production of silica and in particular to the production of silica by flame hydrolysis.
The production of silica by pyrogenic means, for ex-ample, by subjecting silicon tetrachloride to a flame hydrolysis is known. These kinds of silica are, for example, the different silica types marketed under the name of Aerosil ~ They have varying particle sizes ranging from 7 to 40 nm and, therefore can be used in greatly varying fields of application, as for example for the thickening of liquid systems.
The specific surface area, measured in sq m per gram according to BET (not the particle si~e) is usually used as the typical characteristic quantity. Insofar as silicas free from pores are concerned these two quantities are closely correlated.
A characteristic which is just as important is the thickening effect of the different silica types in a liquid system, since most of these silica types are used as thickening and thixo-tropic agents. This characteristic is a function of the BET sur-face area so that in conventional silica types which are produced by means of a flame hydrolysis a specific thickening effect can also be attributed to a specific surface area.
This kind of correlation is shown graphically in Figure 1 of the accompanying drawings, in which:-Figure 1 shows the thickening effect as a function ofthe BET surface area for conventional silicas;
Figure 2 shows the thickening effect as a function of the quantity of added water vapour in correlation to the BET
surface area for silicas produced by means of the process accord-ing to the invention when the additional water vapour is passed in-to the reaction mixture before reaching the combustion chamber;and .~
~79~
Figure 3 shows the thickening effect as a function of the quantity of added water vapour in correlation to the B~T sur-face area for silicas produced by means of the process according to the invention when the additional water vapour is fed into the flame.
In -the known processes of flame hydrolysis of silicon halogen compounds in a hydrogen flame using the hydrolysis of silicon tetrachloride-air or oxygen as an example, hydrogen and silicon tetrachloride are mixed with one another and burned off in such a ratio that the hydrogen can burn completely while form-ing water vapour and that the silicon tetrachloride can react quantitatively with the water vapour formed while forming SiO2.
The reactions which proceed consecutively and concurrently can be represented by the equations 1, 2 and 3:
) 2 H2 2 ~~ 2 H20
" , , The present invention relates to the production of silica and in particular to the production of silica by flame hydrolysis.
The production of silica by pyrogenic means, for ex-ample, by subjecting silicon tetrachloride to a flame hydrolysis is known. These kinds of silica are, for example, the different silica types marketed under the name of Aerosil ~ They have varying particle sizes ranging from 7 to 40 nm and, therefore can be used in greatly varying fields of application, as for example for the thickening of liquid systems.
The specific surface area, measured in sq m per gram according to BET (not the particle si~e) is usually used as the typical characteristic quantity. Insofar as silicas free from pores are concerned these two quantities are closely correlated.
A characteristic which is just as important is the thickening effect of the different silica types in a liquid system, since most of these silica types are used as thickening and thixo-tropic agents. This characteristic is a function of the BET sur-face area so that in conventional silica types which are produced by means of a flame hydrolysis a specific thickening effect can also be attributed to a specific surface area.
This kind of correlation is shown graphically in Figure 1 of the accompanying drawings, in which:-Figure 1 shows the thickening effect as a function ofthe BET surface area for conventional silicas;
Figure 2 shows the thickening effect as a function of the quantity of added water vapour in correlation to the BET
surface area for silicas produced by means of the process accord-ing to the invention when the additional water vapour is passed in-to the reaction mixture before reaching the combustion chamber;and .~
~79~
Figure 3 shows the thickening effect as a function of the quantity of added water vapour in correlation to the B~T sur-face area for silicas produced by means of the process according to the invention when the additional water vapour is fed into the flame.
In -the known processes of flame hydrolysis of silicon halogen compounds in a hydrogen flame using the hydrolysis of silicon tetrachloride-air or oxygen as an example, hydrogen and silicon tetrachloride are mixed with one another and burned off in such a ratio that the hydrogen can burn completely while form-ing water vapour and that the silicon tetrachloride can react quantitatively with the water vapour formed while forming SiO2.
The reactions which proceed consecutively and concurrently can be represented by the equations 1, 2 and 3:
) 2 H2 2 ~~ 2 H20
2) 2 H20 + SiC14 -~ SiO2 + 4 HCl -H2 + 2 + SiC14 ~ Si2 + 4 HCl These equations are also applicable when other silicon halogen compounds are used as starting substances. For this pur-pose vaporizable inorganic halogen compounds and/or organic halo-gen compounds of silicon are used. For example SiHC13, SiC12H2 or SiC14 are useful as inorganie halogen eompounds and CH3SiC13 (CH3)2 SiC12, (CH3)3SiCl, CH3-CH2-SiC13 or (CH3-CH2)3SiC12 as organie halogen compounds.
For earrying out the combustion hydrolysis the compon-ents hydrogen, oxygen or air and silicon tetrachloride are fed, either separately or premixed, to a type of burner sueh as that shown diagrammatieally in the US Patent 2,990,249. The quantity of hydrogen is so ealeulated that, during the formation of water vapour, it is suffieient for a quantitative reaetion of the ehlorine atoms on the silieon atom while forming hydrogen ehloride.
A slight exeess assures that the reaetion proeeeds not only - ~L7~
quantita-tlvely but also exceedingly fast. It is not possible to use an arbitrarily high excess of hydrogen, reiative to the amount of silicon tetrachloride. Quite apart from the fact that this measure would unnecessarily increase the costs of the pro-cess~the hydrogen excess is limited in that not only does this reaction component constitute the component required for the hydrolysis of the chloride but it also supplies the energy. If the increase of the hydrogen excess is too large, the effect would be that the temperature of the flame rises with unfavour-able consequences for the quality of the SiO2 reaction products.
It is also possible to reduce the reaction temperature by adding quantities of air or oxygen which exceed the stoichiometric amount. With this measure the reaction temperature is usually influenced and the fine division or the specific surface area of the reaction products thus is fixed. However, this possibility is limited since the discharge velocity from the burner orifice must move within relatively narrow limits and the increase of the quantity of inert gas is at the expense of the performance of the apparatus.
The known process for producing silicas by means of flame hydrolysis according to the US Patent 2,990,249 has the disadvantage that it is not possihle therewith to change the correlation between specific surface area and thickening pattern and to adjust the thickening effect of the silica independently of the value of the specific surface area.
The present invention provides a process for the con-trolled production of silica by means of flame hydrolysis, char-acterized in that additional amounts of water vapour, which do not result from the combustion of hydrogen or of hydrogen-containing gases required for the flame hydrolysis, are intro-duced into the reaction mixture.
The introduction of the additional water vapour can be ~7~77 carried out in various ways. Thus, the additional water vapour can be passed into the mixing chamber of the burner via a sep-arate conduit. In another preferred embodiment of the process according to the invention the additional water vapour may be fed into the hydrogen or air supply to the burner whereby a mixture of hydrogen and water vapour or a mixture of air and water vapour is fed to the burner. For the mixing with water vapour the hydrogen or the oxygen-containing gas may be passed through a water evaporator at a temperature ranging from 20C
to the boiling temperature of the water.
In a further preferred embodiment the additional water vapour can be admixed with the chloro silicon compound before the latter compound enters the burner. However, the temperature of the mixture from chloro silicon compound must be kept above the dew point in order to avoid separation of silica.
In yet another embodiment of the process according to the invention the additional water vapour can also be fed into the flame, the region of the actual silica formation. This can be done by means of a lance, which is passed axially through the burner and is allowed to project from the burner orifice. How-ever, it is important that the mixing procedure is as fast and homogeneous as possible so that the in~luence of the additional ~-water vapour on the occurrence of the reaction and on the form-tion of the silica can be fully effective since the influence of the partial pressure of the water vapour decreases with the dis-tance from the burner orifice. At the outlet of the so-called flame tube, i.e. a heat exchanger zone, into which the flame gases are usually injected no influence on the formation of pro-perties of the silica upon admixing additional quantities of water vapour is detectable.
The admixed quantity of water vapour may be varied within wide limits.
The wa-ter vapour is preferably added at a temperature from 150 to 250C and at an excess pressure of 10 to 20 atmos-pheres, particularly at a temperature from 185 to 210C and at an excess pressure of 12 to 13~atmospheres.
-,~, c~P~
Any known inorganic/and/or organic silicon h~e~e~
compound can be used as the starting substance.
The ratio of water vapour to starting substance may be from 0.1 to 1 kg of water vapour per kg of starting substance.
In a further embodiment of the invention, e.g. a hydro-carbon, instead of pure hydrogen, may be used as the burner gas.
These hydrocarbons may be for exam le, propane and/or butane.
An apparatus like that described in the US Patent 2,990,249 can be used as the burner. However, a closed burner system, in which no secondary air can penetrate the fîame, may also be usea.
The controllability of the thickening effect is evident from the accompanying drawings.
According to Figure 1 the thickening effect as a func~
tion of the BET surface area is shown graphically for silicas ~0 producèd b~ means of conventional processes. The following values are obtained for the individual silicas:
surface area thickening 130 sq m/g 2000 mPas 150 sq m/g 2700 mPas 200 sq m/g 3100 mPas 300 sq m/g 3500 mPas 380 sq m/g 3000 mPas These thickening values were determined from a polyester reference system.
This poiyester reference system is produced by mixing 80 parts by weight of Ludopal P6 (a trademark) with 11.4 parts by weight of monostyrene and 7 parts by weight of styrene con-,, taining 1 part by weight of paraffin. This system is also used in all the further determinations of the thickening.
According to Figure 2 the entire pattern of properties, particularly the specific surface area and the thickening pattern of the silicas obtained shifts as the amount of water vapour - added increases.
The curve a) thus shows the correlation between the specific BET surface area and the thickening pattern of silicas obtained by means of conventional processes by varying the . .
excess of air. Thus, this measure makes it possible only to - attain the combination of properties of the silicas shown in Figure 1.
;~ However it is evident from the curve b) that as the ' addition of water vapour to the reaction mixture prior to the combustion increases both the thickening pattern and the specific BET surface area first extend far beyond the values known from the conventional silicas according to the curve a) whereupon they substantially decrease with larger quantities o~ water vapour , and new combinations of properties are attained.
;~ 20 For example, it is thus possible to produce silicas ~ having identical BET surface areas but greatly varying patterns ,` of thickening. -` According to Figure 3 the entire pattern of properties ` of the silicas obtained, particularly the specific BET surface area and the pattern of thickening, shifts as the ~uantity of water vapour added increases.
Thus, the curve a) shows the correlation between specific BET surface area and the pattern of thickening in silicas obtained by means of conventional processes by varying i 30 the excess of air. Thus, this measure makes it possible (as shown in Fig. 1 and 2) to attain only a combination of properties in which the thickening effect is a function of the specific BET
surface area.
, However, it is evident from the curve b) that as the addition of water vapour to the flame increases both the pattern - of thickening and the specific BET surface area of the silicas obtained by means of the process according to the invention i follow a path which differs completely from that of the curve a) corresponding to the known silicas, as compared with a basic standard. New combirations of properties can thus be attained.
For example, it is thus possible to produce silicas having identical BET surface areas but greatly varying patterns of thickening.
The process according to the invention is further des-cribed by way of the following Examples.
Example 1 6.2 kg of silicon tetrachloride are evaporated and , mixed with 2.2 cu m of hydrogen and 5.8 cu m of air in the mixing chamber of a burner. The gas mixture burns from the outlet and is sucked into the cooliny system by means of vacuum. After separation from the hydrogen chloride-containing gas mixture 2.2 kg of a highly dispersed silica having a specific surface area of 200 sq m per gram and a thickening of a polyester reference system of 3100 mpascals is obtained.
Example 2 The same procedure as in Example 1 is followed, but in addition to the substances mentioned therein, 0.5 kg of water vapour per hour is injected into the mixing chamber of the burner. The silica obtained has a specific surface of 466 sq m and a thickening value of 3910 mpascals.
Example_3 .
The same procedure as in Example 1, is followed by 1.~
kg of water vapour per hour are additionally added in the manner described in Example 2. The silica has a surface area of 277 sq m per gram and a thickening value of 10~0 mpascals.
~7~477 Example 4 . . _ The same procedure as in Example 1 is followed, but 0.5 kg of water vapour per hour is injected with a probe into the flame axis at a distance of 1 cm from the burner orifice. The silica has a specific surface of 309 sq m per gram and a thicken-ing value of 4040 mpascals.
_xample 5 The same procedure is followed as in Example 1 but with the difference that 3 kg of water vapour are injected into the .
flame axis at a distance of 10 cm from the burner orifice. The BET surface area of the silica is 212 sq per gram and the thick-- ening value 1105 mpascals.
; The values obtained in the above examples of the pro-:' eess according to the invention have been listed in Table I.
The values for the specific surface area and for the thiekening eorrespond to the eurves b) in Figure 2 and 3.
,~
.
, 2~
;' ~
~ ~ 7~77 o . . _ ._ L
L ~> h ,. a .. .Y ~ ~ o~ ~ ~ Lr) N ~D ~D co co CO
h U ~ L' 1-- ~ ~ ('r) ~ o o o ~S rl r~ ; ~I r-l ~1 ~1 ~! r~
.. o ~ a) ~
):~ ~ h ~n .___ , , . __ 41 L' ,~
O .,1 ~
L U Lt~ o In o Ir~ o o Lo ~ o L O u~ ~ D~ o o ~r O .Y (~ O N O ~ 1:~ N O O ~1 ~D r~ O
g ., P~ r N r I N ~ (~ ~ ~) ~ ~1 ~ ~
.~ ,a)~ ~
~" L L
rl O
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---- ~ ~
L ~ S
0~ ~ ~
o a) o ,1 U S-l .
¢1 ~ (~) b) r-l 1-- r~ 1 N
-l~ a) ~ h a~ r o ~1 o ¢ ~ U N O ~ N~r NN~ N~ . :~
o ~ au . h u~ h .~__ =,~
~ 4 4~ O
X ~ O h O r~ h 4~o ~s .~:: a L rl ~ \ h N~Nr~O ~ ~oo~
00~1 ~) ~ ... -......... ....
.~ ~ h ~ ~00000 ON~O
~) U O '1~ ~ ~J
L 1~ h~ ~1 h (~~1 ~ O O
h ~ L
U ~ ~ r1 r~
':U ~ ~) O O . _ , ,,,._____ ~ _ ~ Q
u~ L L' u~
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O rl h \ o~ D
h~ ~ -rl ~ ....... , ., Q ~ ~ E~
L _ . .___ .. ; CO~
. N\ ~NNNNNN NNNN
. ~)~ ~ . . ~ . . . . . . . .
L ~ NNNNNNN NNNN
`:' ~ _ h ~r \ NNNNNNN NNNN
~ rl~ ~.............. ....
O U~ ~ ~ D
., .~._ _,,.. ___ ., ,.
For earrying out the combustion hydrolysis the compon-ents hydrogen, oxygen or air and silicon tetrachloride are fed, either separately or premixed, to a type of burner sueh as that shown diagrammatieally in the US Patent 2,990,249. The quantity of hydrogen is so ealeulated that, during the formation of water vapour, it is suffieient for a quantitative reaetion of the ehlorine atoms on the silieon atom while forming hydrogen ehloride.
A slight exeess assures that the reaetion proeeeds not only - ~L7~
quantita-tlvely but also exceedingly fast. It is not possible to use an arbitrarily high excess of hydrogen, reiative to the amount of silicon tetrachloride. Quite apart from the fact that this measure would unnecessarily increase the costs of the pro-cess~the hydrogen excess is limited in that not only does this reaction component constitute the component required for the hydrolysis of the chloride but it also supplies the energy. If the increase of the hydrogen excess is too large, the effect would be that the temperature of the flame rises with unfavour-able consequences for the quality of the SiO2 reaction products.
It is also possible to reduce the reaction temperature by adding quantities of air or oxygen which exceed the stoichiometric amount. With this measure the reaction temperature is usually influenced and the fine division or the specific surface area of the reaction products thus is fixed. However, this possibility is limited since the discharge velocity from the burner orifice must move within relatively narrow limits and the increase of the quantity of inert gas is at the expense of the performance of the apparatus.
The known process for producing silicas by means of flame hydrolysis according to the US Patent 2,990,249 has the disadvantage that it is not possihle therewith to change the correlation between specific surface area and thickening pattern and to adjust the thickening effect of the silica independently of the value of the specific surface area.
The present invention provides a process for the con-trolled production of silica by means of flame hydrolysis, char-acterized in that additional amounts of water vapour, which do not result from the combustion of hydrogen or of hydrogen-containing gases required for the flame hydrolysis, are intro-duced into the reaction mixture.
The introduction of the additional water vapour can be ~7~77 carried out in various ways. Thus, the additional water vapour can be passed into the mixing chamber of the burner via a sep-arate conduit. In another preferred embodiment of the process according to the invention the additional water vapour may be fed into the hydrogen or air supply to the burner whereby a mixture of hydrogen and water vapour or a mixture of air and water vapour is fed to the burner. For the mixing with water vapour the hydrogen or the oxygen-containing gas may be passed through a water evaporator at a temperature ranging from 20C
to the boiling temperature of the water.
In a further preferred embodiment the additional water vapour can be admixed with the chloro silicon compound before the latter compound enters the burner. However, the temperature of the mixture from chloro silicon compound must be kept above the dew point in order to avoid separation of silica.
In yet another embodiment of the process according to the invention the additional water vapour can also be fed into the flame, the region of the actual silica formation. This can be done by means of a lance, which is passed axially through the burner and is allowed to project from the burner orifice. How-ever, it is important that the mixing procedure is as fast and homogeneous as possible so that the in~luence of the additional ~-water vapour on the occurrence of the reaction and on the form-tion of the silica can be fully effective since the influence of the partial pressure of the water vapour decreases with the dis-tance from the burner orifice. At the outlet of the so-called flame tube, i.e. a heat exchanger zone, into which the flame gases are usually injected no influence on the formation of pro-perties of the silica upon admixing additional quantities of water vapour is detectable.
The admixed quantity of water vapour may be varied within wide limits.
The wa-ter vapour is preferably added at a temperature from 150 to 250C and at an excess pressure of 10 to 20 atmos-pheres, particularly at a temperature from 185 to 210C and at an excess pressure of 12 to 13~atmospheres.
-,~, c~P~
Any known inorganic/and/or organic silicon h~e~e~
compound can be used as the starting substance.
The ratio of water vapour to starting substance may be from 0.1 to 1 kg of water vapour per kg of starting substance.
In a further embodiment of the invention, e.g. a hydro-carbon, instead of pure hydrogen, may be used as the burner gas.
These hydrocarbons may be for exam le, propane and/or butane.
An apparatus like that described in the US Patent 2,990,249 can be used as the burner. However, a closed burner system, in which no secondary air can penetrate the fîame, may also be usea.
The controllability of the thickening effect is evident from the accompanying drawings.
According to Figure 1 the thickening effect as a func~
tion of the BET surface area is shown graphically for silicas ~0 producèd b~ means of conventional processes. The following values are obtained for the individual silicas:
surface area thickening 130 sq m/g 2000 mPas 150 sq m/g 2700 mPas 200 sq m/g 3100 mPas 300 sq m/g 3500 mPas 380 sq m/g 3000 mPas These thickening values were determined from a polyester reference system.
This poiyester reference system is produced by mixing 80 parts by weight of Ludopal P6 (a trademark) with 11.4 parts by weight of monostyrene and 7 parts by weight of styrene con-,, taining 1 part by weight of paraffin. This system is also used in all the further determinations of the thickening.
According to Figure 2 the entire pattern of properties, particularly the specific surface area and the thickening pattern of the silicas obtained shifts as the amount of water vapour - added increases.
The curve a) thus shows the correlation between the specific BET surface area and the thickening pattern of silicas obtained by means of conventional processes by varying the . .
excess of air. Thus, this measure makes it possible only to - attain the combination of properties of the silicas shown in Figure 1.
;~ However it is evident from the curve b) that as the ' addition of water vapour to the reaction mixture prior to the combustion increases both the thickening pattern and the specific BET surface area first extend far beyond the values known from the conventional silicas according to the curve a) whereupon they substantially decrease with larger quantities o~ water vapour , and new combinations of properties are attained.
;~ 20 For example, it is thus possible to produce silicas ~ having identical BET surface areas but greatly varying patterns ,` of thickening. -` According to Figure 3 the entire pattern of properties ` of the silicas obtained, particularly the specific BET surface area and the pattern of thickening, shifts as the ~uantity of water vapour added increases.
Thus, the curve a) shows the correlation between specific BET surface area and the pattern of thickening in silicas obtained by means of conventional processes by varying i 30 the excess of air. Thus, this measure makes it possible (as shown in Fig. 1 and 2) to attain only a combination of properties in which the thickening effect is a function of the specific BET
surface area.
, However, it is evident from the curve b) that as the addition of water vapour to the flame increases both the pattern - of thickening and the specific BET surface area of the silicas obtained by means of the process according to the invention i follow a path which differs completely from that of the curve a) corresponding to the known silicas, as compared with a basic standard. New combirations of properties can thus be attained.
For example, it is thus possible to produce silicas having identical BET surface areas but greatly varying patterns of thickening.
The process according to the invention is further des-cribed by way of the following Examples.
Example 1 6.2 kg of silicon tetrachloride are evaporated and , mixed with 2.2 cu m of hydrogen and 5.8 cu m of air in the mixing chamber of a burner. The gas mixture burns from the outlet and is sucked into the cooliny system by means of vacuum. After separation from the hydrogen chloride-containing gas mixture 2.2 kg of a highly dispersed silica having a specific surface area of 200 sq m per gram and a thickening of a polyester reference system of 3100 mpascals is obtained.
Example 2 The same procedure as in Example 1 is followed, but in addition to the substances mentioned therein, 0.5 kg of water vapour per hour is injected into the mixing chamber of the burner. The silica obtained has a specific surface of 466 sq m and a thickening value of 3910 mpascals.
Example_3 .
The same procedure as in Example 1, is followed by 1.~
kg of water vapour per hour are additionally added in the manner described in Example 2. The silica has a surface area of 277 sq m per gram and a thickening value of 10~0 mpascals.
~7~477 Example 4 . . _ The same procedure as in Example 1 is followed, but 0.5 kg of water vapour per hour is injected with a probe into the flame axis at a distance of 1 cm from the burner orifice. The silica has a specific surface of 309 sq m per gram and a thicken-ing value of 4040 mpascals.
_xample 5 The same procedure is followed as in Example 1 but with the difference that 3 kg of water vapour are injected into the .
flame axis at a distance of 10 cm from the burner orifice. The BET surface area of the silica is 212 sq per gram and the thick-- ening value 1105 mpascals.
; The values obtained in the above examples of the pro-:' eess according to the invention have been listed in Table I.
The values for the specific surface area and for the thiekening eorrespond to the eurves b) in Figure 2 and 3.
,~
.
, 2~
;' ~
~ ~ 7~77 o . . _ ._ L
L ~> h ,. a .. .Y ~ ~ o~ ~ ~ Lr) N ~D ~D co co CO
h U ~ L' 1-- ~ ~ ('r) ~ o o o ~S rl r~ ; ~I r-l ~1 ~1 ~! r~
.. o ~ a) ~
):~ ~ h ~n .___ , , . __ 41 L' ,~
O .,1 ~
L U Lt~ o In o Ir~ o o Lo ~ o L O u~ ~ D~ o o ~r O .Y (~ O N O ~ 1:~ N O O ~1 ~D r~ O
g ., P~ r N r I N ~ (~ ~ ~) ~ ~1 ~ ~
.~ ,a)~ ~
~" L L
rl O
' ~ U
---- ~ ~
L ~ S
0~ ~ ~
o a) o ,1 U S-l .
¢1 ~ (~) b) r-l 1-- r~ 1 N
-l~ a) ~ h a~ r o ~1 o ¢ ~ U N O ~ N~r NN~ N~ . :~
o ~ au . h u~ h .~__ =,~
~ 4 4~ O
X ~ O h O r~ h 4~o ~s .~:: a L rl ~ \ h N~Nr~O ~ ~oo~
00~1 ~) ~ ... -......... ....
.~ ~ h ~ ~00000 ON~O
~) U O '1~ ~ ~J
L 1~ h~ ~1 h (~~1 ~ O O
h ~ L
U ~ ~ r1 r~
':U ~ ~) O O . _ , ,,,._____ ~ _ ~ Q
u~ L L' u~
,1 O ~
O rl h \ o~ D
h~ ~ -rl ~ ....... , ., Q ~ ~ E~
L _ . .___ .. ; CO~
. N\ ~NNNNNN NNNN
. ~)~ ~ . . ~ . . . . . . . .
L ~ NNNNNNN NNNN
`:' ~ _ h ~r \ NNNNNNN NNNN
~ rl~ ~.............. ....
O U~ ~ ~ D
., .~._ _,,.. ___ ., ,.
Claims (10)
PROPERTY OR PRIVELEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In the production of silica by flame hydrolysis of a chloro silicon compound, a process for changing the correlation of specific surface and thickening characteristics, the thicken-ing effect of the silica being adjusted independently of the value of the specific surface, the improvement in which the additional amounts of water vapour which do not result from the combustion of hydrogen required for the flame hydrolysis are fed into the reaction mixture and the mixing operation is carried out as rapidly and homogeneously as possible so that the influence of the additional water vapour on the reaction and the formation of silica is fully effective.
2. A process as claimed in Claim 1 in which the addit-ional water vapour is passed into a mixing chamber of a burner with which the flame hydrolysis is effected.
3. A process as claimed in Claim 1 in which the addit-ional water vapour is fed to a hydrogen or air supply in a burner effecting the flame hydrolysis.
4. A process as claimed in Claim 1 in which the addit-ional water vapour is admixed with reactant chloro silicon compound in the flame hydrolysis fed to a burner.
5. A process as claimed in Claim 1 in which the addit-ional water vapour is fed to the flame of the flame hydrolysis and into the hydrolysis region.
6. A process as claimed in Claim 5 in which the addit-ional water vapour is fed axially into the flame by means of a lance.
7. A process as claimed in Claim 1, 2 or 3 in which the additional water vapour is added at a temperature from 150°C
to 250°C at an excess pressure of 10 to 20 atmospheres.
to 250°C at an excess pressure of 10 to 20 atmospheres.
8. A process as claimed in Claim 1, 2 or 3 in which the additional water vapour is added at a temperature from 185°C
to 210°C at an excess pressure of 12 to 18 atmospheres.
to 210°C at an excess pressure of 12 to 18 atmospheres.
9. A process as claimed in Claim 1, 2 or 3 in which the flame hydrolysis is effected on a halogen silicon compound selected from SiHCl3, SiCl2H2 and SiCl4.
10. A process as claimed in Claim 1, 2 or 3 in which the flame hydrolysis is effected on a chloro silicon compound selected from CH3SiCl3, (CH3)2 SiCl2, (CH3)3SiCl, CH3-CH2-SiCl3 and (CH3-CH2)3 SiCl2.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2904199.4-41 | 1979-02-05 | ||
| DE19792904199 DE2904199A1 (en) | 1979-02-05 | 1979-02-05 | METHOD FOR THE GUIDED PRODUCTION OF SILICON BY MEANS OF FLAME HYDROLYSIS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1179477A true CA1179477A (en) | 1984-12-18 |
Family
ID=6062146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000344998A Expired CA1179477A (en) | 1979-02-05 | 1980-02-04 | Process for the controlled production of silica by means of flame hydrolysis |
Country Status (14)
| Country | Link |
|---|---|
| EP (1) | EP0015315B1 (en) |
| JP (1) | JPS55104912A (en) |
| AT (2) | ATE4303T1 (en) |
| BE (1) | BE881534A (en) |
| BR (1) | BR8000517A (en) |
| CA (1) | CA1179477A (en) |
| CH (1) | CH642931A5 (en) |
| DE (2) | DE2904199A1 (en) |
| FR (1) | FR2447887A1 (en) |
| GB (1) | GB2044738B (en) |
| IT (1) | IT7969244A0 (en) |
| LU (1) | LU81909A1 (en) |
| NL (1) | NL7908270A (en) |
| SE (1) | SE8000877L (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3016010C2 (en) * | 1980-04-25 | 1985-01-10 | Degussa Ag, 6000 Frankfurt | Process for the pyrogenic production of silica |
| DE3028364C2 (en) * | 1980-07-26 | 1983-07-21 | Degussa Ag, 6000 Frankfurt | Process and apparatus for the pyrogenic production of silicon dioxide |
| JPS5788020A (en) * | 1980-11-14 | 1982-06-01 | Ube Ind Ltd | Manufacture of very finely grained anhydrous silica |
| GB8905966D0 (en) * | 1989-03-15 | 1989-04-26 | Tsl Group Plc | Improved vitreous silica products |
| DE10163939A1 (en) * | 2001-12-22 | 2003-07-10 | Degussa | Layer obtained from an aqueous dispersion containing flame-hydrolytically produced silicon-titanium mixed oxide powder |
| DE10312970A1 (en) * | 2003-03-24 | 2004-10-14 | Degussa Ag | Fumed silica powder and dispersion thereof |
| DE10326049A1 (en) * | 2003-06-10 | 2004-12-30 | Degussa Ag | Flame hydrolytically produced silicon dioxide, process for its production and use |
| DE102005001408A1 (en) * | 2005-01-12 | 2006-07-20 | Degussa Ag | Pyrogenic silica powder |
| EP3390303B1 (en) | 2015-12-18 | 2024-02-07 | Heraeus Quarzglas GmbH & Co. KG | Production of quartz glass bodies with dewpoint control in a melting furnace |
| TWI840318B (en) | 2015-12-18 | 2024-05-01 | 德商何瑞斯廓格拉斯公司 | Quartz glass body, light guide, illuminant, formed body, and process for preparing the same, and use of silicon component |
| TWI794149B (en) | 2015-12-18 | 2023-03-01 | 德商何瑞斯廓格拉斯公司 | Quartz glass grain, opaque formed body and process for preparing the same |
| EP3390290B1 (en) | 2015-12-18 | 2023-03-15 | Heraeus Quarzglas GmbH & Co. KG | Production of an opaque quartz glass body |
| EP3390296B1 (en) | 2015-12-18 | 2024-09-04 | Heraeus Quarzglas GmbH & Co. KG | Production of a quartz glass body in a multichamber furnace |
| KR20180095622A (en) | 2015-12-18 | 2018-08-27 | 헤래우스 크바르츠글라스 게엠베하 ＆ 컴파니 케이지 | Manufacture of Silica Glass Products from Molten Crucibles Made of Refractory Metals |
| TWI808933B (en) | 2015-12-18 | 2023-07-21 | 德商何瑞斯廓格拉斯公司 | Quartz glass body, silicon dioxide granulate, light guide, illuminant, and formed body, and process for preparing the same |
| US11492285B2 (en) | 2015-12-18 | 2022-11-08 | Heraeus Quarzglas Gmbh & Co. Kg | Preparation of quartz glass bodies from silicon dioxide granulate |
| EP3390308B1 (en) | 2015-12-18 | 2024-08-28 | Heraeus Quarzglas GmbH & Co. KG | Glass fibres of quartz glass with low oh, cl and al contents |
| KR20180095879A (en) | 2015-12-18 | 2018-08-28 | 헤래우스 크바르츠글라스 게엠베하 ＆ 컴파니 케이지 | Treating the carbon-doped silica granules at elevated temperatures to reduce the alkaline earth metal content of the silica granules |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1967235A (en) * | 1931-09-08 | 1934-07-24 | Karl A Ferkel | Method and apparatus for production of metal oxides |
| CH221309A (en) * | 1941-12-03 | 1942-05-31 | Hans Dr Preis | Process and device for the production of a finely divided oxide of those elements of group IVa of the periodic table which are capable of forming volatile chlorides. |
| US2488440A (en) * | 1946-11-30 | 1949-11-15 | Du Pont | Titanium dioxide pigment production |
| US3130008A (en) * | 1949-11-23 | 1964-04-21 | Cabot Corp | Method of preparing metallic oxides by hydrolysis of metallic halides |
| DE974723C (en) * | 1950-10-02 | 1961-04-13 | Albrecht-Wolf Mantzel | Vehicle wheel with ring-shaped, elastic intermediate links |
| BE508951A (en) * | 1951-02-07 | |||
| DE952891C (en) * | 1954-01-23 | 1956-11-22 | Degussa | Process for the production of finely divided metal oxides and mixtures thereof |
| US2990249A (en) * | 1958-10-09 | 1961-06-27 | Degussa | Process of preparing finely divided oxides by hydrolysis |
| GB1211702A (en) * | 1966-12-08 | 1970-11-11 | Unilever Ltd | Fine particles |
| US3660025A (en) * | 1970-07-01 | 1972-05-02 | Cities Service Co | Manufacture of pigmentary silica |
| BE790704A (en) * | 1971-10-28 | 1973-02-15 | Degussa | PROCESS FOR THE MANUFACTURE OF OXIDES FINE |
| CH569670A5 (en) * | 1972-09-15 | 1975-11-28 | Lonza Ag |
-
1979
- 1979-02-05 DE DE19792904199 patent/DE2904199A1/en not_active Withdrawn
- 1979-11-12 NL NL7908270A patent/NL7908270A/en not_active Application Discontinuation
- 1979-11-19 LU LU81909A patent/LU81909A1/en unknown
- 1979-11-20 IT IT7969244A patent/IT7969244A0/en unknown
- 1979-12-04 AT AT79104898T patent/ATE4303T1/en not_active IP Right Cessation
- 1979-12-04 DE DE7979104898T patent/DE2966007D1/en not_active Expired
- 1979-12-04 EP EP79104898A patent/EP0015315B1/en not_active Expired
-
1980
- 1980-01-03 FR FR8000062A patent/FR2447887A1/en active Granted
- 1980-01-28 BR BR8000517A patent/BR8000517A/en unknown
- 1980-02-04 CH CH88680A patent/CH642931A5/en not_active IP Right Cessation
- 1980-02-04 SE SE8000877A patent/SE8000877L/en not_active Application Discontinuation
- 1980-02-04 BE BE6/47072A patent/BE881534A/en not_active IP Right Cessation
- 1980-02-04 GB GB8003648A patent/GB2044738B/en not_active Expired
- 1980-02-04 AT AT0060480A patent/ATA60480A/en not_active IP Right Cessation
- 1980-02-04 CA CA000344998A patent/CA1179477A/en not_active Expired
- 1980-02-05 JP JP1215780A patent/JPS55104912A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ATA60480A (en) | 1984-08-15 |
| DE2904199A1 (en) | 1980-08-07 |
| JPS55104912A (en) | 1980-08-11 |
| IT7969244A0 (en) | 1979-11-20 |
| FR2447887A1 (en) | 1980-08-29 |
| ATE4303T1 (en) | 1983-08-15 |
| BE881534A (en) | 1980-08-04 |
| FR2447887B1 (en) | 1984-09-07 |
| EP0015315A1 (en) | 1980-09-17 |
| JPS6335567B2 (en) | 1988-07-15 |
| DE2966007D1 (en) | 1983-09-01 |
| GB2044738A (en) | 1980-10-22 |
| BR8000517A (en) | 1980-10-14 |
| GB2044738B (en) | 1983-05-11 |
| CH642931A5 (en) | 1984-05-15 |
| SE8000877L (en) | 1980-08-06 |
| EP0015315B1 (en) | 1983-07-27 |
| NL7908270A (en) | 1980-08-07 |
| LU81909A1 (en) | 1980-04-22 |
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| MKEX | Expiry |