CA1291860C - Water scavengers for hydrochloric acid streams - Google Patents
Water scavengers for hydrochloric acid streamsInfo
- Publication number
- CA1291860C CA1291860C CA000532331A CA532331A CA1291860C CA 1291860 C CA1291860 C CA 1291860C CA 000532331 A CA000532331 A CA 000532331A CA 532331 A CA532331 A CA 532331A CA 1291860 C CA1291860 C CA 1291860C
- Authority
- CA
- Canada
- Prior art keywords
- water
- sic14
- hcl
- stream
- chloride
- 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 - Fee Related
Links
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 title claims abstract description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 27
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 12
- 239000010703 silicon Substances 0.000 claims abstract description 12
- 229910052751 metal Inorganic materials 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims abstract description 8
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 8
- 239000007787 solid Substances 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 5
- 239000007789 gas Substances 0.000 description 22
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 20
- 239000002516 radical scavenger Substances 0.000 description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 14
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 9
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 235000012431 wafers Nutrition 0.000 description 5
- 230000002378 acidificating effect Effects 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- 238000006116 polymerization reaction Methods 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 150000002736 metal compounds Chemical class 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- CHRJZRDFSQHIFI-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;styrene Chemical compound C=CC1=CC=CC=C1.C=CC1=CC=CC=C1C=C CHRJZRDFSQHIFI-UHFFFAOYSA-N 0.000 description 2
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 2
- 229910010066 TiC14 Inorganic materials 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000003446 ligand Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 150000003377 silicon compounds Chemical class 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- KPZGRMZPZLOPBS-UHFFFAOYSA-N 1,3-dichloro-2,2-bis(chloromethyl)propane Chemical compound ClCC(CCl)(CCl)CCl KPZGRMZPZLOPBS-UHFFFAOYSA-N 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- YSVZGWAJIHWNQK-UHFFFAOYSA-N [3-(hydroxymethyl)-2-bicyclo[2.2.1]heptanyl]methanol Chemical compound C1CC2C(CO)C(CO)C1C2 YSVZGWAJIHWNQK-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 229920001429 chelating resin Polymers 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000003100 immobilizing effect Effects 0.000 description 1
- ZUBZATZOEPUUQF-UHFFFAOYSA-N isopropylhexane Natural products CCCCCCC(C)C ZUBZATZOEPUUQF-UHFFFAOYSA-N 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- -1 polyvinyl alcohol Chemical compound 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- FDNAPBUWERUEDA-UHFFFAOYSA-N silicon tetrachloride Chemical class Cl[Si](Cl)(Cl)Cl FDNAPBUWERUEDA-UHFFFAOYSA-N 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/26—Drying gases or vapours
- B01D53/28—Selection of materials for use as drying agents
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B7/00—Halogens; Halogen acids
- C01B7/01—Chlorine; Hydrogen chloride
- C01B7/07—Purification ; Separation
- C01B7/0706—Purification ; Separation of hydrogen chloride
- C01B7/0718—Purification ; Separation of hydrogen chloride by adsorption
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Drying Of Gases (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Catalysts (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Treating Waste Gases (AREA)
Abstract
WATER SCAVENGERS FOR HYDROCHLORIC ACID STREAMS
Abstract of the Disclosure The water content of an HC1 gas stream is reduced to less than 1 ppm by contacting the gas stream with a chloride of silicon or a metal having a valence of at least four.
Abstract of the Disclosure The water content of an HC1 gas stream is reduced to less than 1 ppm by contacting the gas stream with a chloride of silicon or a metal having a valence of at least four.
Description
8h'0 This invention relates to a process for the removal of trace amounts of water from gaseous hydrochloric acid. This invention especially relates to the use of certain chlorides as scavengers to reduce the water content of HCl gas streams to less than one part per million (ppm).
The process of this invention for reducing the water con-tent of HCl gas streams to less than one part per million com-prises contacting the HCl gas stream with a chloride of sili-con or a metal having a valence of at least four. The chlo-ride is preferably immobili~ed on a solid support.
Ordinarily it is difficult to remove trace amounts ofwater from HCl, since HCl is more reactive than water and is hygroscopic. However, silicon and certain high valency metals react more easily with oxide ligands than with chloride ligands. Such metals include, for example, Ti, Zr and W.
Typical reactions include the following:
WC16 + 3~2 ~~~ WO3 + 6HCl (1>
SiC14 + 2H20 --- SiO2 + 4HCl (2) Other suitable chlorides include, but are not limited to, TiC14 and ZrC14.
In some applications it will be advantageous to use the scavengers of this invention at a low temperature that is above the boiling point of HCl. The equilibrium constants will be larger for the removal of water if the temperature is low. This effect i9 important for scavengers having a low equilibrium constant at room temperatu.e, e.g., WC16.
Another effect of low temperature is the lowering of the lZ918~
- Z -vapor pressure of liquid scavengers such as SiC14 and TiC14, which have a high vapor pressure at room temper-ature. The high vapor pressure may lead to the emission of metal or silicon compounds into the purified HCl stream.
Solid scavengers such as WC16 and ZrC14 can be adsorbed on a solid support such as a macroreticulate styrene-divinylbenzene polymer to increase the surface area of the scavenger.
The vapor pressure of liquid chloride scavengers may be decreased without lowering the temperature below room temper-ature by immobilizing the chloride on a solid support having free -OH groups or OM' groups on its surface, where M~ is an alkali or alkaline earth metal. Such supports include high surface area inorganic supports such as alumina and silica.
Polymers containing a functional group that is reactive with the chloride, e.g., polyvinyl alcohol, may also be used as the support. The immobilization takes place according to the following reaction, using SiC14 as an example:
SiC14 + HOMO3 --- C13SiOMO3 + HCl (3) where HOMO3 represents a metal oxide or hydroxide surface.
SiC14 immobilized on alumina is the preferred scavenger.
The liquid chloride scavengers can be reacted with the solid support directly, or they can be heated to vaporize them be-fore contact with the support. If the support is treated with a gaseous chloride, the support with the immobilized chloride on its surface should subsequently be treated with hot HCl gas to drive off any loosely bound chloride.
For applications in which the emission of metal or sili-con compounds into the purified HCl stream would be detri-mental, it is advisable to heat the alumina with the immobi-lized chloride on its surface to a temperature of about 190C
for 17 hours under nitrogen before contact with the HCl stream. This heat treatment will drive off any weakly bound metal or silicon chlorides. The capacity of the chloride-lZ91~fiO
alumina scavenger is typically about 2 liters of water vaporper liter of bed. The purified gas stream can subsequently be passed through a post-trap containing activated alumina to remove any remaining traces of silicon or metal compounds.
5 For example, after passing through a heat-treated SiC14/
A1203 scavenger and an activated alumina post-trap, the level of silicon in the purified HCl stream is typically less than 0.05 ppm (measured by atomic adsorption after passing the HCl stream through 100 ml water). The alumina used in the post-trap is preferably heated in a stream of nitrogen at about 190C for 17 hours and cooled before use.
The water content of the purified gas stream is less than one ppm, and preferably less than 0.5 ppm.
The removal of moisture from an HCl gas stream to mini-mize oxidation reactions is important in the semiconductorindustry. For example, moisture-free HCl is needed for clean-ing ovens used in the manufacture of semiconductor wafers to prevent subsequent contamination of wafers, and for the etch-ing of silicon wafers to prevent the formation of oxides on the surface of the wafers. Anhydrous gaseous HCl is used for the conversion of ferrosilicon (FeSi) to HSiC13, which in turn is used for the manufacture of silicon wafers. The pre-vention of corrosion of tubing used for transporting HCl is also an important consideration.
Example 1 Acidic A1203 (WoelmR A, Akt.l, manufactured by Woelm Pharma GmbH & Co.) is packed into a stainless steel 150 ml sample cylinder. The alumina is dried under a stream of N2 at 200C for 10 hours.
A silicon tetrachloride-functionalized A12O3 scaven-ger is prepared as follows. The bed of dried A1203 is flooded with a 30 volume percent solution of SiC14 in hexane and the SiC14 is left in contact with the bed for at least one hour. The bed is then washed with four bed volumes of sparged hexane. The sample is dried at 65C under a stream ~ f;~
of N2 to drive off the hexane. The functionalized alumina is then held at 190C for 17 hours to drive off volatile component 6 .
An aliquot of the heat-treated scavenger is placed in a 4" polymerization tube. N2 is passed through the sample.
No acidity is detected with tricolor pH paper. N2 i8 then bubbled through water in a 4" polymerization tube and the water-laden gas is passed through the scavenger. The off-gas becomes acidic, indicating that the SiC14 is capable of re-moving moisture from the gas stream according to equation (2).
Example 2 A silicon tetrachloride-functionalized A1203 scaven-ger is prepared and tested as described in Example 1, except that the dried alumina is flooded with neat SiC14 rather than a solution of SiC14 in hexane. The reaction mixture is allowed to stand for at least one hour before heating to drive off volatile components.
Example 3 Acidic alumina is packed into a one-gallon stainless steel reactor. The alumina is dried overnight under a stream of N2 at 190C.
A silicon tetrachloride-functionalized aluminia scavenger is prepared as follows. Silicor, tetrachloride (250 ml) is transferred via a cannula into a bubbler heated to a tempera-ture of 57C. Nitrogen is passed through the heated SiC14until all of the SiC14 has evaporated and has passed through the alumina in the reactor. ~Cl gas that has been heated by passing through a preheating coil is then passed through the SiC14-functionalized alumina for five hours to drive off any loosely bound SiC14. The scavenger is then held at a temperature of 190C under a stream of nitrogen for at least eight hours to remove excess ~Cl.
Ij ~, _ 5 _ ~ O
Example 4 The capacity of SiC14-functionalized alumina scavengers to remove water from a gas stream is measured by the following procedure. N2 is bubbled through water held at 24OC. The vapor pressure of water at this temperature is 24 mm Hg. The wet N2 is passed at a rate of 200 ml per minute through a 30 ml sample of the scavenger in a polymerization tube. The off-gas from the tube containlng the scavenger is passed through 200 ml of water. The gas is fed through a Teflon tube since a stainless steel line produces grounding problems with the pH electrode. The H+ concentration of the water is measured with a pH meter as a function of time. The flow rate of the wet N2 is 0.302 standard liters per minute. Knowing the volume of the water trap, the volume of the bed and the final proton concentration of the water trap, the capacity of the bed can be calculated. The capacities of the various forms of the SiC14/A12O3 scavengers are as follows:
Scavenger Capacity (liters H20 vapor/liter of bed) SiC14 in hexane 1.95 20 SiC14 in hexane, 2.6 heat treated Neat SiC14 5.5 Neat SiC14, heat 2 treated Example 5 A stream of dry HCl gas is mixed with nitrogen contain-ing a known amount of moisture so that the HCl stream con-tains 5 ppm water. The HCl stream is then passed under one atmosphere pressure through a 500 ml column containing the heat-treated SiC14/A1203 scavenger prepared as described lZ31i~
in Example 1. The flow rate of the HCl gas through the column is 160 volumes of gas per volume of bed per hour and the pro-cess is carried out at room temperature The moisture level of the exit gas is measured at 1/2 hour intervals for a two hour period. This procedure is repeated using HCl ga~ streams containing 13 and 37 ppm water. The procedure is again re-peated using a gas stream containing 20 ppm water, except that the flow rate is increased to 760 volumes of ~Cl per volume of bed per hour. In each case the moisture content of the HCl stream at the end of the two hour period is less than 0.1 ppm. The moisture content of the HCl stream was measured as described in Flaherty et al., Anal. Chem. 1986, 58, 1903-1904.
~xample 6 15 Macroreticulate styrene/divinylbenzene (PSDVB) polymer (Amberlite XAD4, manufactured by Rohm and ~aas) is washed with water and the fines are removed by decantation. The polymer is washed in turn with 3 bed volumes of water, metha-nol, isopropyl alcohol and hexane. Air is passed through the bed for about two hours to remove the bulk of the solvents.
The air-dried resin is packed into a stainless steel reactor and dried under a stream of nitrogen at llO~C for 10-12 hours.
A supported WC16 scavenger is prepared as follows.
The dried PSDVB (25 g) is mixed with WC16 (2.52 g) in 50 ml sparged toluene. A nitrogen stream is passed through the mixture at 110C overnight to remove toluene.
PSDVB having WC16 adsorbed on its surface is trans-ferred to a buret for testing. Dry nitrogen is passed through the PSDVB-WC16 scavenger. No acidity is detected with tri-color pH paper. N2 is then bubbled through water in a 4"
polymerization tube and the water-laden gas is passed through the scavenger. The off-gas becomes acidic, indicating that the WC16 is capable of removing moisture from the gas stream according to equation (1).
X
The process of this invention for reducing the water con-tent of HCl gas streams to less than one part per million com-prises contacting the HCl gas stream with a chloride of sili-con or a metal having a valence of at least four. The chlo-ride is preferably immobili~ed on a solid support.
Ordinarily it is difficult to remove trace amounts ofwater from HCl, since HCl is more reactive than water and is hygroscopic. However, silicon and certain high valency metals react more easily with oxide ligands than with chloride ligands. Such metals include, for example, Ti, Zr and W.
Typical reactions include the following:
WC16 + 3~2 ~~~ WO3 + 6HCl (1>
SiC14 + 2H20 --- SiO2 + 4HCl (2) Other suitable chlorides include, but are not limited to, TiC14 and ZrC14.
In some applications it will be advantageous to use the scavengers of this invention at a low temperature that is above the boiling point of HCl. The equilibrium constants will be larger for the removal of water if the temperature is low. This effect i9 important for scavengers having a low equilibrium constant at room temperatu.e, e.g., WC16.
Another effect of low temperature is the lowering of the lZ918~
- Z -vapor pressure of liquid scavengers such as SiC14 and TiC14, which have a high vapor pressure at room temper-ature. The high vapor pressure may lead to the emission of metal or silicon compounds into the purified HCl stream.
Solid scavengers such as WC16 and ZrC14 can be adsorbed on a solid support such as a macroreticulate styrene-divinylbenzene polymer to increase the surface area of the scavenger.
The vapor pressure of liquid chloride scavengers may be decreased without lowering the temperature below room temper-ature by immobilizing the chloride on a solid support having free -OH groups or OM' groups on its surface, where M~ is an alkali or alkaline earth metal. Such supports include high surface area inorganic supports such as alumina and silica.
Polymers containing a functional group that is reactive with the chloride, e.g., polyvinyl alcohol, may also be used as the support. The immobilization takes place according to the following reaction, using SiC14 as an example:
SiC14 + HOMO3 --- C13SiOMO3 + HCl (3) where HOMO3 represents a metal oxide or hydroxide surface.
SiC14 immobilized on alumina is the preferred scavenger.
The liquid chloride scavengers can be reacted with the solid support directly, or they can be heated to vaporize them be-fore contact with the support. If the support is treated with a gaseous chloride, the support with the immobilized chloride on its surface should subsequently be treated with hot HCl gas to drive off any loosely bound chloride.
For applications in which the emission of metal or sili-con compounds into the purified HCl stream would be detri-mental, it is advisable to heat the alumina with the immobi-lized chloride on its surface to a temperature of about 190C
for 17 hours under nitrogen before contact with the HCl stream. This heat treatment will drive off any weakly bound metal or silicon chlorides. The capacity of the chloride-lZ91~fiO
alumina scavenger is typically about 2 liters of water vaporper liter of bed. The purified gas stream can subsequently be passed through a post-trap containing activated alumina to remove any remaining traces of silicon or metal compounds.
5 For example, after passing through a heat-treated SiC14/
A1203 scavenger and an activated alumina post-trap, the level of silicon in the purified HCl stream is typically less than 0.05 ppm (measured by atomic adsorption after passing the HCl stream through 100 ml water). The alumina used in the post-trap is preferably heated in a stream of nitrogen at about 190C for 17 hours and cooled before use.
The water content of the purified gas stream is less than one ppm, and preferably less than 0.5 ppm.
The removal of moisture from an HCl gas stream to mini-mize oxidation reactions is important in the semiconductorindustry. For example, moisture-free HCl is needed for clean-ing ovens used in the manufacture of semiconductor wafers to prevent subsequent contamination of wafers, and for the etch-ing of silicon wafers to prevent the formation of oxides on the surface of the wafers. Anhydrous gaseous HCl is used for the conversion of ferrosilicon (FeSi) to HSiC13, which in turn is used for the manufacture of silicon wafers. The pre-vention of corrosion of tubing used for transporting HCl is also an important consideration.
Example 1 Acidic A1203 (WoelmR A, Akt.l, manufactured by Woelm Pharma GmbH & Co.) is packed into a stainless steel 150 ml sample cylinder. The alumina is dried under a stream of N2 at 200C for 10 hours.
A silicon tetrachloride-functionalized A12O3 scaven-ger is prepared as follows. The bed of dried A1203 is flooded with a 30 volume percent solution of SiC14 in hexane and the SiC14 is left in contact with the bed for at least one hour. The bed is then washed with four bed volumes of sparged hexane. The sample is dried at 65C under a stream ~ f;~
of N2 to drive off the hexane. The functionalized alumina is then held at 190C for 17 hours to drive off volatile component 6 .
An aliquot of the heat-treated scavenger is placed in a 4" polymerization tube. N2 is passed through the sample.
No acidity is detected with tricolor pH paper. N2 i8 then bubbled through water in a 4" polymerization tube and the water-laden gas is passed through the scavenger. The off-gas becomes acidic, indicating that the SiC14 is capable of re-moving moisture from the gas stream according to equation (2).
Example 2 A silicon tetrachloride-functionalized A1203 scaven-ger is prepared and tested as described in Example 1, except that the dried alumina is flooded with neat SiC14 rather than a solution of SiC14 in hexane. The reaction mixture is allowed to stand for at least one hour before heating to drive off volatile components.
Example 3 Acidic alumina is packed into a one-gallon stainless steel reactor. The alumina is dried overnight under a stream of N2 at 190C.
A silicon tetrachloride-functionalized aluminia scavenger is prepared as follows. Silicor, tetrachloride (250 ml) is transferred via a cannula into a bubbler heated to a tempera-ture of 57C. Nitrogen is passed through the heated SiC14until all of the SiC14 has evaporated and has passed through the alumina in the reactor. ~Cl gas that has been heated by passing through a preheating coil is then passed through the SiC14-functionalized alumina for five hours to drive off any loosely bound SiC14. The scavenger is then held at a temperature of 190C under a stream of nitrogen for at least eight hours to remove excess ~Cl.
Ij ~, _ 5 _ ~ O
Example 4 The capacity of SiC14-functionalized alumina scavengers to remove water from a gas stream is measured by the following procedure. N2 is bubbled through water held at 24OC. The vapor pressure of water at this temperature is 24 mm Hg. The wet N2 is passed at a rate of 200 ml per minute through a 30 ml sample of the scavenger in a polymerization tube. The off-gas from the tube containlng the scavenger is passed through 200 ml of water. The gas is fed through a Teflon tube since a stainless steel line produces grounding problems with the pH electrode. The H+ concentration of the water is measured with a pH meter as a function of time. The flow rate of the wet N2 is 0.302 standard liters per minute. Knowing the volume of the water trap, the volume of the bed and the final proton concentration of the water trap, the capacity of the bed can be calculated. The capacities of the various forms of the SiC14/A12O3 scavengers are as follows:
Scavenger Capacity (liters H20 vapor/liter of bed) SiC14 in hexane 1.95 20 SiC14 in hexane, 2.6 heat treated Neat SiC14 5.5 Neat SiC14, heat 2 treated Example 5 A stream of dry HCl gas is mixed with nitrogen contain-ing a known amount of moisture so that the HCl stream con-tains 5 ppm water. The HCl stream is then passed under one atmosphere pressure through a 500 ml column containing the heat-treated SiC14/A1203 scavenger prepared as described lZ31i~
in Example 1. The flow rate of the HCl gas through the column is 160 volumes of gas per volume of bed per hour and the pro-cess is carried out at room temperature The moisture level of the exit gas is measured at 1/2 hour intervals for a two hour period. This procedure is repeated using HCl ga~ streams containing 13 and 37 ppm water. The procedure is again re-peated using a gas stream containing 20 ppm water, except that the flow rate is increased to 760 volumes of ~Cl per volume of bed per hour. In each case the moisture content of the HCl stream at the end of the two hour period is less than 0.1 ppm. The moisture content of the HCl stream was measured as described in Flaherty et al., Anal. Chem. 1986, 58, 1903-1904.
~xample 6 15 Macroreticulate styrene/divinylbenzene (PSDVB) polymer (Amberlite XAD4, manufactured by Rohm and ~aas) is washed with water and the fines are removed by decantation. The polymer is washed in turn with 3 bed volumes of water, metha-nol, isopropyl alcohol and hexane. Air is passed through the bed for about two hours to remove the bulk of the solvents.
The air-dried resin is packed into a stainless steel reactor and dried under a stream of nitrogen at llO~C for 10-12 hours.
A supported WC16 scavenger is prepared as follows.
The dried PSDVB (25 g) is mixed with WC16 (2.52 g) in 50 ml sparged toluene. A nitrogen stream is passed through the mixture at 110C overnight to remove toluene.
PSDVB having WC16 adsorbed on its surface is trans-ferred to a buret for testing. Dry nitrogen is passed through the PSDVB-WC16 scavenger. No acidity is detected with tri-color pH paper. N2 is then bubbled through water in a 4"
polymerization tube and the water-laden gas is passed through the scavenger. The off-gas becomes acidic, indicating that the WC16 is capable of removing moisture from the gas stream according to equation (1).
X
Claims (2)
1. In a process for reducing the water content of an HCl gas stream, the improvement comprising reducing the water content to less than 1 ppm by contacting the gas stream with a chloride of silicon or a chloride of a metal having a valence of at least four that is immobilized on a solid support.
2. The process of claim 1 wherein the chloride of silicon is SiC14 and the support is alumina.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US84144086A | 1986-03-19 | 1986-03-19 | |
| US841,440 | 1986-03-19 | ||
| US868387A | 1987-01-29 | 1987-01-29 | |
| US008,683 | 1987-01-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1291860C true CA1291860C (en) | 1991-11-12 |
Family
ID=26678469
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000532331A Expired - Fee Related CA1291860C (en) | 1986-03-19 | 1987-03-18 | Water scavengers for hydrochloric acid streams |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPH0753221B2 (en) |
| KR (1) | KR950006513B1 (en) |
| CA (1) | CA1291860C (en) |
| DE (1) | DE3709084C2 (en) |
| FR (1) | FR2595958B1 (en) |
| GB (1) | GB2188043B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4853148A (en) * | 1987-03-24 | 1989-08-01 | Advanced Technology Materials, Inc. | Process and composition for drying of gaseous hydrogen halides |
| JPH11139805A (en) | 1997-07-29 | 1999-05-25 | Millipore Corp | Composition and method for removing water content from hydrogen halide |
| US5958356A (en) * | 1997-11-05 | 1999-09-28 | Air Products And Chemicals, Inc. | Method for removal of moisture from gaseous HCl |
| AU6512200A (en) * | 1999-08-17 | 2001-03-13 | Dow Chemical Company, The | Production of anhydrous hydrogen chloride from byproduct or waste chlorinated materials |
| US6221132B1 (en) | 1999-10-14 | 2001-04-24 | Air Products And Chemicals, Inc. | Vacuum preparation of hydrogen halide drier |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD150736A1 (en) * | 1980-04-14 | 1981-09-16 | Gerhard Appel | METHOD FOR DRYING CHLORINE HYDROGEN AND CHLORINE |
| JPS57104995A (en) * | 1980-12-22 | 1982-06-30 | Casio Computer Co Ltd | Keyboard circuit for adding touch response |
-
1987
- 1987-03-18 GB GB8706444A patent/GB2188043B/en not_active Expired
- 1987-03-18 CA CA000532331A patent/CA1291860C/en not_active Expired - Fee Related
- 1987-03-19 FR FR878703824A patent/FR2595958B1/en not_active Expired - Fee Related
- 1987-03-19 KR KR1019870002469A patent/KR950006513B1/en not_active Expired - Fee Related
- 1987-03-19 JP JP62065518A patent/JPH0753221B2/en not_active Expired - Fee Related
- 1987-03-19 DE DE3709084A patent/DE3709084C2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0753221B2 (en) | 1995-06-07 |
| GB8706444D0 (en) | 1987-04-23 |
| GB2188043A (en) | 1987-09-23 |
| GB2188043B (en) | 1989-11-15 |
| KR870008782A (en) | 1987-10-20 |
| KR950006513B1 (en) | 1995-06-16 |
| JPS62254822A (en) | 1987-11-06 |
| FR2595958A1 (en) | 1987-09-25 |
| DE3709084A1 (en) | 1987-09-24 |
| DE3709084C2 (en) | 1995-09-21 |
| FR2595958B1 (en) | 1991-06-14 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |