DE2608169A1 - REMOVAL OF HYDROGEN FLUID FROM GASEOUS MIXTURES - Google Patents

Description

Pennwalt Building, Three Parkway, Philadelphia, Pa. 19102,

V. St. A.

Removal of hydrogen fluoride from gaseous mixtures

The invention relates to the removal of hydrogen fluoride gas (HF) from gaseous mixtures containing up to about 20 % HF, based on the weight of the gaseous mixture, and other gases inert to alkaline earth fluorides, in the absence of water. The gaseous mixture is brought into contact with particulate, non-aqueous alkaline earth chloride in the absence of water. The non-aqueous alkaline earth chloride is preferably fluorinated by contact with a dry, gaseous mixture which, with the exception of a smaller proportion of HF, is inert to alkaline earth chloride . On the other hand, a dry gas containing at least a larger proportion of HP or a dry fluorine gas can also be used to obtain the particulate, non-aqueous alkaline earth fluoride used in the method according to the invention.

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After absorption of HF gas in an amount up to the absorption capacity of the respective non-aqueous alkaline earth metal fluoride, the gas mixture flow is switched off or derived and the absorbed EF removed from the alkaline earth fluoride, preferably by means of desorption Warmth. The regenerated alkaline earth fluoride is then reused in the RF removal process. Liquids that don't are aqueous are tolerable in the gaseous mixture as long as they are not in the process vessels in such Collect quantities that substantial areas of the surface of the absorbent material have been covered.

If the term "absorption" is used below to describe the present process, this term includes as used here, chemisorption, adsorption, and absorption.

The alkaline earth compounds for the purposes of the invention are the calcium, barium or strontium chlorides and fluorides in their non-aqueous form. The preferred alkaline earth metal is calcium and the invention will be discussed further in FIG For the sake of brevity, mainly on the basis of calcium. The non-aqueous forms of alkaline earth chlorides are obtained by the hydrates are dried at temperatures suitable for removing water of hydration.

The gaseous mixtures for the purposes of the invention which contain up to about 20% HF, based on the weight of the gaseous mixture, and other gases inert to alkaline earth fluorides include mixtures of HF # hydrogen chloride (KCl) and volatile organic gases, as they occur in various manufacturing processes, HF and HCl mixtures that are essentially free of other gases, HF and fluorine gas with and without other inert gases, dry air that contains traces of HF, exhaust gases from petroleum alkylation processes that involve of non-aqueous HF, exhaust gases from the aluminum metal and ceramics industries, the traces of HF

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hold, etc.

The method according to the invention is particularly suitable for the treatment of gaseous hydrogen chloride contaminated with HF, such as occurs as a by-product in the synthesis of fluorocarbons. In technical processes for the production of fluorinated hydrocarbons (such as CCl ^ F, CCl ₂ F ₂ , CClF ₅ , CHCl ₂ F, CHClF ₂ , CHF ₅ , CH ₅ CClF ₂ , CH ₅ CCl ₂ F, CH ₅ CF ₅ , CCl ₂ FCClF ₂ , CClF ₂ CClF ₂ and the like, i.e. products that are suitable as refrigerants, blowing agents and aerosol propellants), which under fluorination of chlorinated hydrocarbons, such as CCI4, CHCl ₅ , CH ₅ CCl ₅ and CCl ₂ -CCl ₂ , run with HF, a significant amount of hydrogen chloride, which contains varying but substantial proportions of hydrogen fluoride, as a by-product, the hydrogen chloride by-product cannot be discarded for obvious economic and ecological reasons. However, this contaminated hydrogen chloride must be purified so that the HCl can be used for technical purposes, e.g. B. in oxychlorination reactions, in food processing, in pickling of steel and in the treatment of salt solution, which is used in the electrolytic chlorine production; the presence of HF in such systems cannot be tolerated.

US Pat. No. 3,140,916 recommends a method for removing HF contamination in which a gaseous mixture of hydrogen chloride and hydrogen fluoride is passed through an aqueous calcium chloride solution, whereby the hydrogen fluoride reacts with the calcium chloride in solution to form calcium fluoride as a precipitated solid, - which can be obtained by filtration. This multi-step aqueous technique has several serious disadvantages resulting from the problems involved in handling an aqueous system formed by HCl, CaCl ₂ and CaF ₂ . This mixture is highly corrosive and the mixture of precipitated CaF ₂ in water forms a slurry giving rise to strong abrasive forces; both conditions are very disadvantageous for apparatus. In

609842/0863

The patent rift also mentions that alumina is used as a Absorbent has been used to remove HF from HCl.

A simple and economical method of removal of HF contamination from a gaseous mixture of hydrogen chloride is disclosed in U.S. Patent Application Serial No. 35 ^ 715 which is based on United States patent application Serial Uo. 153 * 839 (DT-OS 2,229,571) decreases. With the procedure described there becomes gaseous HGl, which contains HF, with essentially non-aqueous, solid, particulate! Calcium chloride brought in contact. It has been shown that the calcium fluoride, which is obtained there by way of the conversion of CaClp in situ, has the ability to up to something absorb over 50% of its own weight in HF. In addition this calcium fluoride keeps the size, the shape, the appearance, the free flow and other easy handling Resulting characteristics of the precursor calcium chloride at.

VL Colvin describes * in the "AEG Beport K ΛΛΛψ ^1" the use of calcium fluoride as a sorbent for hydrogen fluoride, the calcium fluoride being produced by the birefluorination of calcium sulphate. However, only a very small load was obtained for the level breakthrough of HF According to the invention, an average load of about 20 % HF is achieved on GaFU ^fee i normal operation.

Colvin also mentions a surface area of 129 m / g for his material. The calcium fluoride material used according to the invention has a much smaller surface area, such as from about to 17 m / g. The method according to the invention thus gives that unexpected result of removing more HP per unit weight of absorbent with considerably less surface area.

609842/0883

Laboratory tests have shown that naturally occurring calcium fluoride is not capable of producing an essential Amount of HF to absorb. Naturally occurring calcium fluoride could only be about 5 to 6 wt.% HF before the breakthrough absorb, while the calcium fluoride produced by the reaction of calcium chloride and HF about 20 wt.% HF before breakthrough able to absorb under the same flow, temperature and pressure conditions.

The term "breakthrough ¹¹ corresponds to the following in the meaning used here: '

Venn HF by passing a gas containing HF therethrough is absorbed by an absorption medium, then applies to the HF concentration in the exiting gas that it is in general is fairly steady or increasing slowly. If the exit concentration of HF in the gas is rapid (im Comparison with the previous speeds) begins to increase, the "breakthrough" has occurred.

Table I summarizes measurements of the surface area and RF absorption for calcium fluoride (CaFp) by passage of non-aqueous HF through a layer of non-aqueous calcium chloride (CaClp) in the absence of water until transfer of the CaClp in CaFp as determined by analysis of the solids. The absorbed HF was then through Desorbed heat and air purge.

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tab 4th Specific upper * 1.8 2608169 IR-2051 e 1 1 e I area, m2 / g +) Physical parameters 13.5 2.0 link 16.5 sample HF,%, on CaF ₂ CaF ₂ absorbed I. CaFp 40 II CaFo (more natural 40 III Fluorspar) CaCl ₂ (not 10 IV aqueous)

+) determined by the American BET method

Chemical Societies (Brunauer, Emmet & Teller)

These results show a marked change in the physical structure of the compound CaClp when it reacts with HF to form CaF ₂ . Sample III also includes natural fluorskid, CaF ₂ , the surface of which is in the order of magnitude of that of CaCl ₂ . The fluorspar absorbs only 10% HF under the same conditions as samples I and II.

The HF absorbed by the "synthetic" calcium fluoride obtained in the manner described above can be stripped off with appropriate heating devices; _{the CaF 2} regenerated in this way can then again serve as an absorbent for further HF present in the gaseous mixture.

That treated to effect RF removal according to the invention HF-containing, gaseous mixture can contain 0.3 to about 20% by weight of HF, based on the total weight of the gaseous Mixture. The regenerative circulatory system according to However, the invention is particularly suitable for the 'mixtures containing massive amounts of HF, e.g. B. from about 0.5 to 6.0 wt%. In an even more valuable application of the process

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Rens can be mixed with a gaseous hydrogen chloride mixture containing EF up to about 70, but preferably up to about 60% by weight, based on the total weight of the gaseous mixture, of one or more volatile halogenated hydrocarbons , ie chlorofluorocarbons, chlorofluorocarbons and fluorocarbons, e.g. B- CCl ₄ , CCl ₃ E, CCl ₂ F ₂ , CClE ₃ , CHCl ₂ F, CHClF ₂ , CHF ₃ , CHCl ₃ , CH ₃ CClF ₂ , CH ₃ CCl ₂ F, CCl ₂ FCClF ₂ , CClF ₂ CClF ₂ and CCIoCCl ₂ , and the like. Such volatile halogenated hydrocarbons do not interfere with the HF absorption and are not subject to any noticeable change _{through contact with the CaF 2.} The product HCl can be separated from these organics by distillation to obtain a non-aqueous HCl gas or by absorption in water to obtain an aqueous HCl solution. In the latter technique, the small amount of organic matter absorbed in the aqueous acid can be easily removed by blowing with air or other gas, or by absorption on activated carbon or molecular sieves.

The absorption tower used to carry out the process according to the invention can initially be charged with an appropriate bed or a layer of particulate CaF _{2 which} has been prepared as described above from the essentially non-aqueous calcium chloride, or is, according to the preferred embodiment, with the non-aqueous CaCl ₂ , which is then converted into the CaF ₂ in the normal manner when the feed stream of HF-containing, gaseous HCl is brought into contact with it or passed through it. The particulate calcium fluoride can range from powdery to granular grades to pellets, that is, have an average particle size in the broad range of 0.06 to 1.0 cm (0.025 to 0.375 inches). In the preferred embodiment, however, the calcium fluoride is in pellet form, e.g. B. a particle size of about 0.6 to 1.0 cm (about 0.25 to 0.375 inches).

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The temperature at which bringing the gaseous hydrogen chloride mixture with the particulate CaF ₂ ⁱⁿ Eontakt may range from about 15 to 55 ° C (about 60 to 130 ° F), with a range of about 21 to 4- 5 ° C (about 70 to 115 ° F) is preferred. The contact temperature is expediently kept above the dew point of the gaseous mixture in order to prevent any organic substances present in it from condensing in the reactor column. Pressures can range from substantially atmospheric up to about 18 atmospheres depending on other process conditions. (about 250 psig) are enough. Since the system is essentially non-aqueous, no special materials are required, and the absorption tower and associated piping and equipment can be made of ordinary mild steel, and corrosion thereof does not pose an abnormal problem.

In the sense used here, "non-aqueous ^11" is to be understood as meaning a substance which contains less than 1000 and preferably less than 200 parts by weight of water per million parts of substance (ppm). Correspondingly, the term "in the absence of water" a process carried out with a gas that contains less than 1000 ppm of water

One with the present invention about simplicity of operation and low labor cost, advantage obtained is the overall effectiveness of RF absorption at even relatively high throughputs. For example, after treatment, the product gas contains a gaseous mixture of HCl and organic Substances which have an initial HF content of about 18%, according to the invention usually less than 0.5% by weight of HF, although the feed gas flow rates are in the range of about 0.05 to 50 g / hour per cm (about 1.0 to 100 pounds / square foot) of the particulate CaF ~ can vary, measured under normal conditions of 1 ata pressure and 21 ° C. In other words, the above results regarding HF absorption is achieved using contact times of the gaseous HCl mixture with the particulate calcium

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fluoride (also known as residence time) from about 20 to 600 s received. Of course, these flow velocities have a certain influence on the quality of the product gas (Amount of HF contamination).

The supply of the dry, gaseous mixture to the layer of the particulate CaF ₂ is continued until a corresponding amount of HF has been absorbed therein. This amount can have a maximum of about 50% of the CaF ^ weight, but a factor influencing the absorption efficiency is naturally the amount of free surface remaining in the CaFp solids, so that the HCl gas supply or the supply of material is ended to a fresh tower before the CaFo has absorbed the maximum amount if a comparatively purer HCl product is desired. The so-called "used" CaFp solid is then desorptively regenerated, ie absorbed HF is stripped from the solids. This can be conveniently accomplished using a number of conventional methods: 1. by externally heating the absorption column to about 107 to 177 ° C (about 225 to 350 ° F), 2. by heating the column to 93 ° C (200 ° F) or above and bubbling an inert gas such as nitrogen, air, or non-aqueous HF through the solids, 3 · bubbling an inert gas heated to 177 ° σ (350 ° F) or higher through the solids. The desorbed HF is recovered and can be used in hydrofluorination processes.

The "regenerated" CaF ^ solids layer becomes after cooling used for a further cycle of the treatment HF-containing, gaseous mixture, and after reaching the desired With the value of the RF absorption (as discussed above), the regeneration cycle is repeated. The number of full Cycles for which a given CaF ^ charge can be used is due to actual physical breakdown of the batch is limited due to the heating and cooling cycles. The number of cycles is therefore due to the acceptable pressure drop

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of the system. When this point is reached, the absorption CaF _{2 should be} replaced by a fresh layer or the like or, preferably in the. Substantial non-aqueous, particulate CaCl _{2 are} replaced. The used CaF ₂ -Jfpeststoff (which may have lost its good physical properties due to physical degradation) is obtained from the tower floor. It can be used as raw material for the production of plus acid in a H ^ O. reactor furnace are used.

The following examples serve to further illustrate the invention.

example 1

A gaseous mixture obtained as a by-product of the hydrofluorination of chloroform - formed by hydrogen chloride with a content of about 60% of organic substances (halogenated hydrocarbons, mainly CHClP ₂ and smaller amounts of CHCl ₂ P, CHCl-, and CHP ^) and 10, 3% hydrogen fluoride, based on the weight of the HCl present - was passed through a steel column 2.54 cm in diameter with a 1.01 m filling of particulate calcium fluoride at 1.06 ata and 32 ° C., the gas surface velocities were in the range from 0.05 to 0.5 m / min, which is equivalent to residence times in the order of magnitude of 110 to 330 s. The CaP ₂ had a particle size of 4.8 to 6.4 mm and was obtained from a procedure in which non-aqueous CaCl _{2 of} this particle size range was contacted with a stream of material of essentially the same composition as above in the absence of water.

The HP content of the gaseous HCl mixture was 10.3 0.38%, based on the HCl content, is reduced, which is an efficiency is equivalent to the HP removal of 96.4%. All in all were passed through the bed to an HF absorption therein of 14% by weight of 10.2 L of the feed gas. That

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Calcium fluoride was regenerated by heating the column with an electrical heating tape to 177 ° C (stripping off absorbed HF). The CaF ₂ was then available to treat additional amounts of the HCl feed gas mixture in the same manner.

Example 2

A gaseous mixture obtained as a by-product in the hydrofluorination of methyl chloroform - formed by HCl with a content of about 54 % of volatile halogenated hydrocarbons (mainly CH ₅ CClF ₂ and smaller amounts of CH ₅ CCl ₂ E and CH ₅ CF ₅ ) and 18 % HF, based on the HCl weight - was passed through a steel column with a diameter of 5i1 cm which, according to the invention, had a 0.79 m layer of CaF ₂ . The CaF ₂ was prepared by bubbling the above gaseous mixture through non-aqueous CaCl ₂ in the form of pellets 3.2 to 6.4 mm in diameter. After the CaCl _{2 had been completely converted} into CaF ₂ , the absorbed HF was driven off in an appropriate manner, whereupon the CaFp was ready for reuse as an absorbent. Typical working conditions were a pressure of 0.14 atm and a contact temperature of about 38 ° C. The system was used in four working cycles, with the CaF _{2 being} regenerated between the cycles according to the procedure of the previous example. Results:

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Tabel

II

. cycle
No. ι
ro
I. Treat
tes loading
kungsgas, 1 HP,%,
in the
HOl loading
dispatch In the product
mixture, Effect
degree of
RF distance
tion, % Gasge
dizzy
ability,
m / min Contact
Time,
S. On CaP ₂
absorbed
HB ¹ ,%, am
end of
Cycle _H CD
CD
OD
cn J ^
CD 1 30.3 18th 0.4 98 0.06 780 No. 1
J ro 2 71.1 18th 1.4 92.2 0.73 65 7 q 3 172.3 18th 4-, 7 74 0.40 120 16 4th 182.4 18th 10.1 44 0.50 95 18th Ϊ860Ϊ -> »
ο
co
σ>

IE-2051 ^1Ο

At the end of the fourth cycle, the CaF _{2 was} removed from the column, and it turned out to be a free-flowing solid which did not show any noticeable change in size, shape or appearance.

Example 4

A similar gaseous HCl mixture as in Example 2 was passed through a column 0.61 m in diameter, which had a 1.37 m layer of particulate CaF ₂ , which was produced by passing the gaseous HCl mixture (similar to that in Example 2 used) by non-aqueous CaCl ₂ until the complete conversion of the CaCl ₂ into CaF ₂ and then driving off the absorbed HF in an appropriate way while leaving the CaFp behind. The column was operated at 38 ° C. and 10.9 atmospheres. The gas flow was 57 l / min at a speed of about 0.18 m / min and a contact time of 450 s. The test extended to two cycles, the CaF ^ between the cycles by heating the column from the outside to 204 ° C and passing hot purge nitrogen at 177 C through which CaFp was regenerated to drive off absorbed HF. Results:

Table III

cycle HF in a HCl mixture Product,
% Efficiency to end of the cycle No. Loading
kung, % 2 _t 3
9.3
4th the HF Ent
distance, % on
tes CaF
HF, _o absorbent
H 1
2
at 15.6
15.6
game 85
40 3
10

The following table shows the results of a series of absorption tests using a column 15.2 cm in diameter with a CaFp layer 1.58 m deep, which was made with a mixture of HF, HCl and CH, CC1F _2, together with smaller amounts

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other chlorofluorocarbon compounds or a mixture of HF, HCl and CHClF _{2 was operated in} addition to smaller amounts of other chlorofluorocarbon compounds. All absorption tests were carried out on the same CaFp batch.

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Table IV

cn

CD CO ■ Ρ · »KJ

Ver
search
No.. Gas flow
mung,
l / min Speed
age
m / min Contact
Time,
S. Working
pressure,
atü Stratified
temperature,
⁰ C (Avg
cut) HR,%, in
the HCl
Loading
kung Effect
degree of
RF distance
tion, % average
first layer
loading,
% HF on CaF ₂ 1 22.7 1.22 82.5 3.5 61 19.69 47.23 17.0 2 5.4 0.28 306.9 10.5 49 16.87 61.18 21.0 3 9.1 0.48 207.5 3.9 49 18.75 62.37 17.0 .4 14.7 0.79 126.9 10.9 52 18.12 33.72 19.0 5 20.4 1.10 91.7 3.5 38 18.75 25.00 31.8 6th 5.4 0.28 306.9 10.5 35 • 14.69 12.00 38.0

OO _ *, σ} vn

CD O OO

DG CD

The values given in the table for the HF content of gases and solids were determined according to standard analysis techniques. The layer samples were obtained by "core removal ¹ " from the layer.

Example 5

The following table shows the results of a series of absorption tests using a 0.61 m column Diameter with a CaFp layer 1.37 m deep, which was operated with the gases described in Example 4-. All Absorption tests were carried out on the same batch of CaFp.

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Table V

Ver
search
No. Gas flow
mung,
l / min Speed
age
m / min Contact
Time,
S. Working
pressure,
atü Stratified
temperature,
⁰ C (Avg
cut) HR,%, in
the HCl
Loading
kung effect
degree of
RF distance
tion,% average
first layer
loading,
% HF on CaF ₂ H
Ψ 1 167.9 0.58 142.1 7.0 32 18.75 50.00 13.0 I. 2 351.4 1.20 68.4 3.7 21 20.63 49.09 14.5 VJl 3 137.6 0.47 174.2 10.9 34 13.13 59.52 9.0 4th 56.9 0.20 421.9 10.9 38 15.63 59.60 8.0 5 136.8 0.16 500.0 3.9 35 19.69 59.05 • 7.0 6th 47.9 0.16 500.0 6.0 35 15.94 44.71 3.0 7th 135.1 0.46 177.6 10.5 44 15.38 36.00 35.0

CD CD CO

Example 6

_{The Cai "2} used in the test series of Example 5 was regenerated as follows:

1. The layer with a diameter of 0.61 m was heated to 177 ° C. by supplying heat to the outside of the column with a diameter of 0.61 m. Then dry nitrogen was heated to 204 ° C. with a tube heater and passed through the layer at 3.0 l / min (based on normal conditions) per dm layer area. The HF on the CaF ₂ underwent desorption and was collected in a refrigerated container. The CAFo ^Wai% then completely desorbed while remaining less than 0.5% HF on the CaF. ₂ This method was used in most of the experiments for regeneration.

Another regeneration method is as follows:

2. The CaFg layer with a diameter of 0.61 m was heated to 177 ° C. by supplying heat to the outside of the column with a diameter of 0.61 m. A vacuum corresponding to a residual pressure of about 125 mm Hg was then applied to the layer with a diameter of 0.6 l. The HF underwent desorption from the CaF ₂ and was collected in a cooled receiver. The residual amount of HF on the CaF ₃ was less than 0.5 wt. This method was used in the last two experiments of Example 5. In both cases, the desorption took place in the same direction as the original HF adsorption on the CaF ₂ , ie in the same direction as the absorption flow.

Example 7

_{The CaF 2} in the 15.2 cm diameter column was regenerated as follows:

The column of 15 »2 cm in diameter was" jacketed " provided that the action of water vapor of 10.5 atü

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from the outside of the container. The absorbed HF containing CAFP layer ^wu * de heated to about 177 ° C, followed by air at about 66 ° C with a 0.76 to 3 l / min depending on a varying speed dm CAFP-layer surface (relative to normal conditions) is introduced became. The air was guided in the opposite direction to the direction of the HF absorption, ie in the case of HP absorption from the organic material flow by guiding it from the bottom to the top of the CaF ^ layer, the desorption air was then guided from the top to the bottom of the CaFp layer. The CaJ ^ layer was desorbed to less than 0.5% HF, based on the CaF ^ weight.

Example 8

Barium chloride dihydrate (BaCIg.2HgO) was mixed with calcium chloride dihydrate (CaCIg.2HpO) mixed in a ratio of 9: 1. A wet cake of this mixture was made at a hydraulic

A pressure of 211 kg / cm is pressed into a billet, which then Was dried at 149 ° C for 16 h. The sticks were then crushed and sifted; Fines below 6.4 mm were discarded.

The 6.4 mm pieces were put into a steel tube of 5j1 cm inside diameter and 61.0 cm length, which was set up for sampling at 20.3 and 40.6 cm length and at the exit. 655 grams of the above mixture was added to the tube. That Tube was placed in the gas stream of a chlorofluorocarbon compound containing approximately 3 vol. 1% HF, 36 vol.% HCl and 61 Contained vol% organic matter. After 45 hours that became Tube removed and analyzed. The residence time was about 200 s and the analysis after 45 h showed an absorption of 29.6 wt.% HF on the solid. Analysis of the solid showed the absence of residual chlorides (i.e. complete Conversion).

The following table shows the percentage of the gas flow at different times (starting at 2 hours

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and "up to 45 hours) of removed hydrogen fluoride

Table VI

hours HF, ppm Distant HR, entry exit % 2 12,000 71 99 Λ 5 12,500 84 99.3 8th 13,500 1.620 87.5 18th 16,000 1.710 89.3 24 17,400 1,200 93.0 37 12,300 7,800 36.6 40 12,300 12,000 2.5 45 13,000 11,400 12.0

Dwell time: 200 s
Sample, g: 655 (as BaCl ₂ + CaCl ₂ ) Sample, g: 546.3 (as BaF ₂ + CaF ₂ ) Absorbed HF: 161.7 E Removed HF: 301.6 g (total)

The barium fluoride pellets prepared in the above manner can be prepared according to one of the procedures of Example 6 or 7 be regenerated. The non-aqueous barium fluoride can then used in absorption experiments as in Example 4 or 5.

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609842/08

Claims (16)

Patent applications 1. Process for removing hydrogen fluoride from a gaseous mixture containing up to about 20% of hydrogen fluoride, based on the weight of the gaseous mixture, and other gases inert to alkaline earth fluorides contains, characterized in that the gaseous mixture is in contact with particulate !, non-aqueous Alkaline earth fluoride, obtained by fluorinating particulate, non-aqueous. Alkaline earth chloride in the absence of water, conducts and thereby works in the absence of water and thereby on hydrogen fluoride absorption the non-aqueous alkaline earth fluoride. 2. The method according to claim 1, characterized in that calcium is used as the alkaline earth metal. 3 · The method according to claim 1, characterized in that one works with barium as the alkaline earth metal. 4. The method according to claim 1, characterized in that the fluorination of non-aqueous alkaline earth metal chloride by Reaction of non-aqueous alkaline earth chloride and hydrogen fluoride causes, as a component in a gaseous Mixture with others, compared to the alkaline earth chloride inert gases are present. 5. The method according to claim 4-, characterized in that a gaseous mixture is used, the hydrogen chloride contains. 6. The method according to claim 5 »characterized in that a gaseous mixture is used which contains volatile, halogenated hydrocarbons. - 21 609842/0863 IR-2051 7. The method according to claim 6, characterized in that one works with calcium as an alkaline earth metal. 8. The method according to claim 1, characterized in that the non-aqueous alkaline earth fluoride with hydrogen fluoride absorbed on this is periodically regenerated by removing the hydrogen fluoride absorbed on it and the regenerated, non-aqueous alkaline earth fluoride is used again for the absorption of hydrogen fluoride from the gaseous mixture which is in contact with it . 9. The method according to claim 8, characterized in that a gaseous mixture is used, the hydrogen chloride contains. 10. The method according to claim 9, characterized in that a gaseous mixture is used which contains volatile, halogenated hydrocarbons. 11. The method according to claim 10, characterized in that the fluorination of the particulate, non-aqueous Caused alkaline earth chloride by reacting the same with the hydrogen fluoride present in the gaseous mixture. 12. The method according to one or more of claims 8 to 11, characterized in that calcium is used as the alkaline earth metal. 13. The method according to claim 10, characterized in that one works with calcium as the alkaline earth metal and uses non-aqueous calcium fluoride, its average Particle size for the largest dimension of the particles in the Range from 0.06 to 1.0 mm. 14 ·· The method according to claim 13 »characterized in that the gaseous mixture with the non-aqueous calcium fluoride at a temperature in the range of about 15 his - 22 609842/0863 IR-2051 55 ° C brings together. 15. The method according to claim I ¹ I, characterized in that the gaseous mixture is brought together with the non-aqueous calcium fluoride at a pressure of about atmospheric pressure up to about 18 ata. 16. The method according to claim I _3, characterized in that the non-aqueous alkaline earth chloride is formed by dehydrating the alkaline earth chloride hydrate before the fluorination to give the alkaline earth fluoride. · - 23 - 609842/0863