CA1228190A - Scavengers for the removal of impurities from inert fluids - Google Patents

Abstract

SCAVENGERS FOR THE REMOVAL OF IMPURITIES FROM INERT FLUIDS
Abstract of the Disclosures Disclosed are macroreticulate polymers which are useful in scavenging Lewis acid and oxidant impurities from inert fluids. The macroreticulate polymers of this invention con-tain a plurality of metallated functional groups or mixtures of metallated functional groups where the function groups correspond to the general formula:

where Ar is an aromatic hydrocarbon radical containing from one to three rings; R is selected from the group consisting of alkyl hydrocarbon radicals, benzophenone radicals, salts of benzophenone, fluorenone radicals and salts of fluorenone;
and M is selected from the group consisting of lithium, po-tassium, sodium, alkyl magnesium, and alkyl zinc. Impurities are readily removed from such inert fluids by contacting the fluids with the macroreticulate polymer and then separating the fluids from the scavenger.

Description

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This invention relates to organo-metallic polymers used to scavenge oxidants and Lewis acids from inert fluids (both liquids and gases), and their use.
In numerous products and processes the purity of fluids is of critical importance Often, the presence of even small amounts of Lewis acid or oxidant impurities will dramatically reduce the utility of a fluid.
Among the known methods for purification of inert fluids is the use of scavengers. With this method, a fluid is passed over a scavenger that reacts with and removes impurities without affecting the fluid itself. For example, the fluid may be passed through a bed or column containing the scavenger.
US. Patents 3,079,428 and 3,316,223 disclose processes for scavenging acidic impurities from organic liquids by contacting the liquids with an insoluble polymeric anionic material.
However, there is a continuing need for new and better ways of purifying such fluids. Among the properties that are desired in a good scavenger are the ability to remove a wide variety of impurities and to insure that the remaining level of impurities is low, and the capacity to remove high levels of impurities. Furthermore, it is desirable that a scavenger should be effective not only when swollen by the liquid to be purified, but also that it should be effective with liquids and gases that cannot swell the scavenger. For many applications, it is also desirable that the scavenger should have "uniform loading", that is, some of its reactive sites should not be more reactive than others. If a scavenger does not have uniform loading, it will not behave consistently throughout its lifetime, thereby making it difficult to I

predict how the scavenger will perform at any particular time. It is also desirable that the scavenger should have good thermal stability, and that it should change color as it becomes exhausted, so that the need for replacement is readily determinable.
Cross-linked polymers that remain porous even in the absence of swelling solvents are known, for instance, from Chemical and Engineering News, November 15, 1982, p. 15, which discloses that "functionalized" polystyrene divinely-Bunsen, including lithiated polystyrene divinylbenzene, maybe used as a catalyst support. Taylor, macromolecules, 14, (1981), pp. 135 138, discloses also the treatment of swollen polystyrene divinylbenzene with n-butyl lithium to form an intermediate in the preparation and halogenation of silylated polystyrene. Bates et at., Macromolecules, 14, (1981), pp.
881-883 discloses the treatment of a divinylbenzene gel with n-butyl lithium to detect the presence of vinyl groups in the gel. None of these references discloses means for removing acidic and oxidant impurities from fluids through the use of porous or "macro reticulate" polymers.
According to the invention, all of the desirable properties for a scavenger, discussed above, are found in macro reticulate polymers containing mutilated functional groups, that are characterized in that the functional groups correspond to the general formula:

-Ar-lCH-CH2-R
M

where An is an aromatic hydrocarbon radical containing from one to three rings, R is selected from the group consisting of alkyd hydrocarbon radicals containing from 1 to 12 carbon Lo atoms, benzophenone radicals, alkali or alkaline earth metal salts of benzophenone, fluorenone radicals and alkali or at-Kline earth metal salts of fluorenone; and M it selected from the group consisting of lithium, potassium, sodium, at-Kyle magnesium, and alkyd zinc, where the alkyd groups are at-Kyle hydrocarbon radicals containing from 1 to 12 carbon atoms.
Also according to the invention, a process for the purification of inert fluids containing Lewis acid and oxidant impurities by contacting the liquids with an insoluble polymeric anionic material is characterized in that it comprises contacting the fluid with the macro reticulate polymer according to the invention, and then separating the fluid from the scavenger.
In the preferred polymers according to the invention, the aromatic hydrocarbon radical containing from one to three rings, which may be phenylene, naphthylene, fluorethylene and the like, is preferably phenylene.
R can be an alkyd hydrocarbon radical containing from 1 to 12 carbon atoms. Typical alkyd hydrocarbon radicals in-elude methyl, ethyl, and the various isomers of propel, bottle, ponytail, Huxley, octal, decal and dodecyl. The prefer-red alkyd hydrocarbon radicals are bottle radicals.
Alternatively, R can be either a radical of benzophenone, one of its alkali or alkaline earth metal salts, a radical of fluorenone or one of its alkali or alkaline earth metal salts.
M is a metal or organometal chosen from the group con-sitting of lithium, sodium, potassium, alkyd magnesium or at-Kyle zinc, where the alkyd group is an alkyd hydrocarbon fad-teal containing from about 1 to 12 carbon atoms. The nature of the metal-functional group bond varies depending on the choice of M. where M is potassium, the bond is highly ionic, LO

whereas where M is an alkyd zinc the bond is much more cove-lent. The other possible M's fall somewhere between these two extremes. The greater the ionic nature of the bond, the greater the carbanion character of the functionality. It has been found that the greater the carbanion character, the more reactive the functionality and the more intense the color of the scavenger. Only where M is alkyd zinc is the scavenger not intensely colored.
The polymeric backbone may be any polymer which is both macro reticulate and inert to the mutilated functional groups. The baclcbone must be macro reticulate, i.e., it must possess a porous reticulate structure in the absence of a solvent. generally, the pore size will be in the range of 500 to 1000 nanometers. Such a structure ensures that the scavenger is not adversely effected by the inert fluid, for when the backbone is macro reticulate, the scavenger will not dissolve or swell to an appreciable extent in the fluid.
moreover, because the backbone is macro reticulate r the sun-face area of the scavenger is sufficiently large so that the scavenger is effective in purifying gases and liquids which do not swell the scavenger. The polymeric backbone must not react with the mutilated functional groups for a functional group which reacts with the backbone is not available to scavenge impurities.
The preferred polymer backbone is macro reticulate polystyrene).

In some embodiments it is the most reactive and most in-tensely colored scavenger that will be desired. There are other embodiments, however, where less reactivity is sought and in these situations less reactive mutilated functional groups or mixtures of mutilated functional groups will be employed. The particular mutilated functional group or mix-lure of mutilated functional group best suited for a specie lie application will be readily ascertained by one skilled in the art without undue experimentation following the teachings of their specification.
The loading of the polymer backbone is an indication of the number of functional groups present and is expressed in milli-equivalents of functional groups per milliliter of scavenger. The greater the loading, the greater the capacity of the scavenger. The optimal loading for a particular scat-enter will depend on the polymer backbone, the mutilated functional group, the impurities to be removed and the par-titular application. The proper loading for a particular scavenger will be readily ascertained by one skilled in the art. In general, the loading will be from about 0.01 to about 3.0 and preferably from about 0.05 to about 2.5 Millie equivalents of functional group per milliliter of scavenger.
The scavengers of this invention are stable at tempera-lures as high as 72C for prolonged periods of time and stable at temperatures as high as 135C for short periods of time.
The scavenger of this invention is preferably Cynthia-sized by mutilating macro reticulate polymers having pendant aromatic vinyl groups. The preferred macro reticulate polymer is commercially available macro reticulate polystyrene-divinylbenzene) (hereinafter referred to as PSDVB). This material has the requisite pendant groups.
The terminal double bonds of the macro reticulate polymer are mutilated with an organometallic compound such as an ~LZ2~L9~

alkyd lithium, alkyd sodium, alkyd potassium, dialkyl magnet slum, alkyd magnesium halide or dialkyl zinc, where the alkyd group is an alkyd hydrocarbon radical containing from about 1 to 12 carbon atoms; or with a salt of a benzophenone radical-anion or dianion or a salt of a fluorenone radical-anion or dianion. The preferred organometallic compounds are left-bottle lithium, dibutyl magnesium and sodium/potassium salts of the benzophenone radical-anion or dianion.
Mutilation reactions are well known in the art. The mutilation can be achieved simply by contacting the macro-reticulate polymer starting material with a solution contain-in the organometallic compound. Typical solvents for the organometallic compound include aliphatic hydrocarbons, art-matte hydrocarbons and ethers. The contacting is carried out at ambient temperature and pressure. The time for the con-tatting is typically in the range of from 10 minutes to 10 hours. Other methods of synthesis of the scavenger will be known to those skilled in the art.
The mutilated polymer scavenger of this invention is used to purify any material which is a gas or liquid at the conditions under which it is contacted with the scavenger and which is inert to the scavenger's mutilated functionalities.
Representative of the fluids which may be treated are elf-phatic hydrocarbons, including methane, ethanes propane, butane, pontoon, hexane, Hutton, octane, decant, dodecane and the like; olefins including ethylene, propylene, l-butene and the like, (but not those olefins which would react with the mutilated functionalities such as, those having an adja-cent aromatic group including styrenes those having a coinage-grated double bond, including 1, 3-butadiene and those con-twining acidic protons including allele and cyclopentadiene);
and inert gases including nitrogen, argon, helium, xenon, hydrogen and carbon tetrafluoride.

I

The mutilated polymers effectively scavenge a wide variety of impurities such as oxidants and Lewis acids. A
Lewis acid is a compound which can accept a pair of elect irons. Representative impurities include oxygen, water, alcohols, phenols, aldehydes, kittens, carboxylic acids, car-bun dioxide, carbon monoxide; alpha-acetylenes, allele, con-jugated dines, peroxides, sulfur compounds and the like.
Apparently the mutilated functional group is capable of no moving impurities by at least three mechanisms: oxidation, deprotonation and mutilation.
The macro reticulate polymer can be contained in any de-vice comprising a chamber which is impermeable to the fluid to be purified and having an inlet port and an outlet port to allow the impure fluid to enter mid chamber and the purified fluid to exit respectively. Preferably, the device is trays-lucent so that any loss of color of the scavenger can be ox-served. Such devices are known in the art. Typical devices include beds and columns. The precise configuration of a de-vice will depend upon the scavenger, the fluid and the impure flies. The optimal size and configuration for a particulars will be readily determinable by one skilled in the art without undue experimentation. In some embodiments it will be desirable to initially pack the device with unmetallated PSDVB and then carry out the above described mutilation react lion using the device as the reaction vessel. because the scavengers are largely insensitive to swelling in the inert fluids, columns can be packed to full volume without concern for large volume changes.
The impurities are removed in accordance with the pro-cuss of this invention by passing the fluid containing impure flies over the macro reticulate polymer, for example, by past sing the impure fluid through a bed or column containing the mutilated polymer. The time required will depend on the scavenger, the inert fluid and the composition and concentra-lion of the impurities. The -time required for a particular situation will be readily ascertained by one skilled in the art.

I Lo To determine if the proper conditions have been chosen for a particular situation, one need only to take an Alcott of the fluid after it has been passed through the scavenger and test for the presence of impurities using any appropriate analytic method. A particularly useful method is simply to pass the fluid though an indicator solution after the fluid has been passed through the scavenger.
There is an additional benefit in using a scavenger where the metal-functional group bond has ionic character.
Such scavengers are intensely colored. As the mutilated functional group reacts with impurities, the metal-functional group bond is destroyed and consequently the scavenger loses - its intense color and turns white. When the color is gone, the scavenging power has been depleted, so that the absence of color serves as an indication that the scavenger needs to be replaced.
This also means that scavengers which have a metal-functional group bond having sufficient ionic character may be used as indicator for the various Lewis acid and oxidant impurities with which they react. A color change indicates that these impurities are present, whereas when there is no change in color, the fluid is free from the impurities The following examples are to further illustrate the invention and not to limit it.
Example 1 Lithiated polystyrenedivinylbenzene (Hereinafter revered to as PSDVB) is prepared in the following manner. Macro-reticulate PSDVB polymer (Amberlite~XAD4 manufactured by Room & Hays) is washed with three bed volumes of water, then moth-anon, then isopropanol and finally hexane. One bed volume is equal to the volume of the unfilled bed. The polymer is placed in a reaction vessel and for about two hours dried us-don a stream of nitrogen at 120C. The reaction vessel is then flooded with 2 molar tert-butyl lithium. The mixture is agitated occasional for two hours.

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The resulting polymer reaction product is then washed with hexane and dried with nitrogen at room temperature. The no-suiting product is a lithiated polymer of this invention, which is dark red and turns white upon reaction with impurities.
The lithiated polymer is used to fill a 500 ml. glass column. Nitrogen, containing the impurities listed below is passed through the bed at a flow rate of 40 volumes of gas per volume of bed per hour. In order to determine if any imp purities remain in the nitrogen after it is passed therewith bed; the nitrogen is passed through an indicator soul-lion. The indicator solution consists of 5 ml. of diglyme which contains 2.5 micro moles of sodium anthracene. The anthracene will decolonize if any impurities are left in the nitrogen. It is found that the lithiated polymer scavenger removes oxygen (41 micro moles), isopropanol (50 micro moles), carbon dioxide (41 micro moles), and acetone (54 micro moles).
A 30 ml. serum vial containing about 3 ml. of the lithe-axed polymer is pressurized to 10 prig with nitrogen. One ml. of carbon monoxide is added. Within three minutes, there is no detectable carbon monoxide present in the nitrogen gas.
Example 2 Butylmagnesium polystyrenedivinylbenzene is prepared in the following manner. The procedure of Example 1 is followed except that the clean PSDVB polymer is flooded with 0.7 M
Bu2Mg and reacted at room temperature for one hour. The resulting product is a macro reticulate polymer of this invent lion which is yellow and turns white upon reaction with impurities.
Example 3 Potassium benzophenone polystyrenedivinylbenzene is pro-pared in the following manner. Sixty ml. of PSDVB polymer is placed in one side of a vessel having two 250-ml. round-bottom flasks joined by a coarse Fritz 4~2 g. benzophenone in 75 ml. tetrahydrofuran is added to the other side.

ISSUE

Then sodium/potassium alloy is added to the benzophenone solution. The solution immediately turns blue. When the solution becomes purple, the thus formed potassium buoyancy phenone dianion solution is transferred to the side contain-in the polymer. The solution is then returned back to thesodium/potassium alloy side and an additional 75 ml. of tetrahydrofuran is added. After one-half hour the solution is transferred back to the side containing polymer and left overnight. The product is washed with 400 ml. tetrahydro-Furman, then 300 ml. hexane and finally nitrogen dried. The product a macro reticulate polymer of this invention, which is black to reflected light and when crushed under an inert at-misfire is blue-purple and turns white upon reaction with impurities.
Example 4 In a crown capped vessel is placed 400 ml. of purified hexane delineate and a Teflon covered magnetic stir bar. The delineate is then sparred with purified nitrogen for about 50 minutes. The vessel is placed in a constant temperature bath at 50C. Then, the vessel is attached to a propylene manic fold and flushed with propylene for several minutes in order to remove the nitrogen.
To the hexane delineate is added 1.2 ml. of a 1.36 M dip ethyl aluminum chloride in hexane and then 0.3 moles of Tokyo. The propylene is polymerized at a temperature of 65C under 30 prig propylene pressure for 2.5 hours.
The polymerization is repeated following the same prove-dune except that the propylene gas is first purified by past sing it through a 400 ml. column, packed with a lithiated polystyrenedivinylbenzene prepared as outlined in Example 1.
Without purification, the yield of insoluble polymer is 4.0 g. and the percent insoluble yield is 97%. With purify-cation, the yield of insoluble polymer is 5.0 g. and the per-cent insoluble yield is 98%.

Claims (21)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A macroreticulate polymer, useful as a scavenger for Lewis acid and oxidant impurities, containing a plurality of functional groups or mixtures of functional groups where the functional groups correspond to the general formula:

where Ar is an aromatic hydrocarbon radical containing from one to three rings; R is selected from the group consisting of alkyl hydrocarbon radicals containing from 1 to 12 carbon atoms, benzophenone radicals, alkali or alkaline earth metal salts of benzophenone; fluorenone radicals and alkali or al-kaline earth metal salts of fluorenone; and M is selected from the group consisting of lithium, potassium, sodium, al-kyl magnesium, and alkyl zinc where the alkyl groups are hy-drocarbon alkyl radicals containing from 1 to 12 carbon atoms.

2. The macroreticulate polymer of claim 1 wherein M is lithium and R is a tert-butyl radical.

3. The macroreticulate polymer of claim 1 wherein M is butyl magnesium and R is a butyl radical.

4. In a device for the purification of fluids compris-ing a chamber which is impermeable to the fluid to be puri-fied, an inlet port at one end of the chamber, an outlet port at the other end of said chamber and where the chamber is filled with a scavenger, the improvement wherein the scaven-ger is the macroreticulate polymer of claim 1.

5. The device of claim 4 wherein the scavenger is the macroreticulate polymer of claim 2.

6. The device of claim 4 wherein the scavenger is the macroreticulate polymer of claim 3.

7. A process for the purification of inert fluids con-taining Lewis acid and oxidant impurities which comprises contacting the fluid with a macroreticulate polymer contain-ing a plurality of functional groups or a mixture of func-tional groups corresponding to the general formula:

where Ar is an aromatic hydrocarbon radical containing from one to three rings; R is selected from the group consisting of alkyl hydrocarbon radicals containing from 1 to 12 carbon atoms, benzophenone radicals, alkali or alkaline earth metal salts of benzophenone; fluorenone radicals and alkali or al-kaline earth metal salts of fluorenone; and M is selected from the group consisting of lithium, potassium, sodium, al-kyl magnesium, or alkyl zinc where the alkyl groups are hydrocarbon alkyl radicals containing from 1 to 12 carbon atoms and then separating the thus contacted fluid from the macroreticulate polymer.

8. The process of claim 7 wherein M is lithium and R is a tert-butyl radical.

9. The process of claim 7 wherein M is butyl magnesium and R is a butyl radical.

10. The process of claim 7 wherein the inert fluid is an aliphatic hydrocarbon.

11. The process of claim 7 wherein the inert fluid is an olefin.

12. The process of claim 11 where the inert fluid is ethylene.

13. The process of claim 11 where the inert fluid is propylene.

14. The process of claim 7 wherein the inert fluid is selected from the group consisting of nitrogen, argon, heli-um, zenon, hydrogen and carbon tetrafluoride.

15. The process of claim 14 where the inert fluid is hydrogen.

16. The proccess of claim 15 where the inert fluid is nitrogen.

17. The process of making a macroreticulate polymer con-taining a plurality or metallated functional groups compris-ing contacting a macroreticulate polymer having pendent aro-matic vinyl groups with a metallating agent selected from the group consisting of alkyl lithium, alkyl sodium, alkyl potas-sium, dialkyl magnesium, alkyl magnesium halide and dialkyl zinc, where the alkyl group is an alkyl hydrocarbon radical containing from about 1 to 12 carbon atoms; alkaline or alka-line earth metal salts of benzophenone and alkali or alkaline earth metal salts of fluorenone.

18. The process of claim 17 wherein the macroreticulate polymer is macroreticulate poly(styrene-divinylbenzene).

19. The process or claim 18 wherein the metallating agent is tert-butyl lithium.

20. The process of claim 18 wherein the metallating agent is dibutyl magnesium.

21. The process of claim 18 wherein the metallating agent is an alkali salt of benzophenone.