NO822880L - REMOVAL OF HYDROCARBON COMPOSITIONS. - Google Patents

Description

This application is a continuation-in-part application in the United States of

U.S. Serial No. 06/221,295, filed December 30, 1980.

The present invention relates to a technique for removing hydrocarbons, including substituted hydrocarbons, from liquid or gas or mixed liquid-gas streams, by bringing the streams into physical contact with an elastomer that will sorb the hydrocarbons that are sought to be removed. Hydrocarbons can be selectively removed from hydrocarbon mixtures or from air-hydrocarbon or aqueous-hydrocarbon mixtures.

Many different methods can be used for separating hydrocarbon compositions from mixtures of several hydrocarbons or aqueous or air mixtures containing hydrocarbons. Examples of such techniques include solvent extraction, fractional distillation, steam cracking, biodegradation and the use of various additives, e.g. activated carbon. Hydrocarbons are known to have the ability to be absorbed by rubber.

The ASTM D471-72 test for change in properties of elastomeric vulcanizates resulting from immersion in liquids measures e.g. the change in weight or volume of the elastomeric test specimen caused by immersion in a liquid. The test is predictive in nature and its purpose is to measure the deleterious effect of a particular fluid on a particular elastomer. It does not recognize the fact that an elastomer is useful as a means of removing hydrocarbon compounds from hydrocarbon-containing liquid and gas mixtures.

An article by L.B. Westover, J.J. Tou and J.H. Mark, entitled "Novel Mass Spectrometics Sampling Device — Hollow Fiber Probe", 46 Analytical Chemistry 568 (April 1974), describes the use of a probe consisting of a hollow fiber of silicone rubber which allows certain hydrocarbons to penetrate to the interior of the fiber, where they can be detected spectrometrically. An article by Patrick R. Jones and Shen K. Yang, entitled "A Liquid Chromatograph/Mass Spectrometer Interface", 47 Analytical Chemistry, 1000 (June 1975), describes a similar use of a silicone rubber membrane separator which allows certain hydrocarbons to pass through the membrane. These statements do not relate to the ability of the silicone rubber to sorb hydrocarbons, but rather to its ability to allow hydrocarbons to pass through.

The present invention builds on the selective sorption phenomenon of elastomers to allow the removal of hydrocarbons from other hydrocarbons or from aqueous mixtures or mixtures with air. "Hydrocarbons" as used herein include aliphatic, and aromatic hydrocarbons, saturated and olefinic, and substituted hydrocarbons including halogenated, sulfonated, oxygenated and nitrated hydrocarbons. Substituents can be other organic radicals, OH, carboxyl, nitrile, sulphonate and others. Hydrocarbons can be removed from organic solutions in which they are present as dissolved solids, from aqueous-organic mixtures and from organic-organic mixtures, in liquid, gaseous or mixed liquid-gaseous states such as air-vapor streams. Depending on the properties of the chosen elastomer, hydrocarbons can be promoted selectively or non-selectively. The procedure is concentration-gradient driven and requires . not the presence of heat (although heat may be helpful to the process in some cases). The process can be carried out at ambient pressure or at any pressure at which the mixture is present. The method also allows for recovery of most removed hydrocarbon compounds.

The method is carried out by bringing the mixture into contact with an elastomer which sorbs the hydrocarbon compounds. The degree of removal of the hydrocarbons from a mixture depends primarily on the amount and type of elastomer, the type of hydrocarbon and the contact time between the mixture and the elastomer. Then the hydrocarbons can, in most cases, be removed by desorbing them from the elastomer. Desorption can be achieved using a number of different methods, e.g. by exposing the elastomer to a vacuum or by displacing the hydrocarbon from the elastomer with a solvent that is more readily absorbed by the elastomer. Since absorption is concentration-gradient driven, simply contacting the elastomer with a gaseous or liquid stream lacking the absorbed molecule will usually desorb it. Heating such a splitting medium promotes desorption.

Many, but not all, elastomers absorb the more aromatic hydrocarbons more readily than the less aromatic hydrocarbons. One embodiment of the invention comprises the removal of aromatic hydrocarbon compositions from a mixed hydrocarbon stream containing both aliphatic and aromatic hydrocarbon compositions. Another embodiment involves the reverse, ie removal of aliphatic hydrocarbons from aliphatic-aromatic mixtures using an elastomer selected for its higher affinity for aliphatics than aromatics. A third embodiment of the invention comprises the removal or selective removal of hydrocarbon compounds from aqueous streams, e.g. wastewater. A fourth embodiment removes or selectively removes hydrocarbons from air streams. A fifth embodiment involves using the absorption capacity of an elastomer to change the relative concentrations among hydrocarbons contained in the same stream.

Other specific embodiments are described herein and further applications of the present method will be readily understood by one skilled in the art.

The invention is particularly useful for treating a number of different industrial process streams. It can e.g. are used to remove, recover and concentrate aromatic hydrocarbons having high octane values from mixed hydrocarbon refinery streams. Various gas streams containing hydrocarbons, e.g. hydrogen gas streams, can be purified while maintaining their pressure by means of the present method. The process allows the removal of hydrocarbons, including aliphatic, saturated and unsaturated hydrocarbons, and aromatic and substituted aromatic hydrocarbons, e.g. benzene, toluene, naphthalene, anthracene, phenols, nitrophenols and toxic halogenated hydrocarbons, including halogenated benzenoid structures including pesticides, insecticides, etc, from waste water without the necessity of heating, activated charcoal or biodegradation. The halogenated forms of many hydrocarbons are more readily absorbed than their non-halogenated forms.

The present invention can be used for the removal and recovery, if desired, of a number of different hydrocarbon compositions which are defined as hydrocarbons and hydrocarbon mixtures including hydrocarbons that have been nitrated, sulphonated, oxygenated and/or halogenated, and other substituted hydrocarbons. Aromatic hydrocarbon compounds are more easily sorbed by many elastomers than olefinic compounds. Examples of unsaturated hydrocarbon ring structures include those of the benzenoid series, naphthalene and anthracene. Saturated and paraffinic hydrocarbons are selectively sorbed by some elastomers as will be seen

in the examples below.

The removal of a hydrocarbon composition is achieved by its sorption on or in an elastomer. For the purposes of the invention, unless otherwise indicated, it does not matter whether the elastomer absorbs or adsorbs the hydrocarbon composition. The terms sorption, absorption and adsorption are used to denote an uptake of a hydrocarbon composition by the elastomer. 'Any elastomer that can sorb the hydrocarbon composition that is sought to be removed from a mixture can be used as long as it satisfies the requirement that it is not easily dissolved or otherwise degraded by the mixture. The elastomer can be a polymer of natural, regenerated, vulcanized or synthetic rubber. Synthetic elastomers have the advantage that they are usually more chemically inert to the mixture being treated and the hydrocarbons being sorbed. However, natural rubber has a high sorption capacity. Reclaimed rubber such as from tires or other scrap sources is often preferred when large volumes of elastomer are required due to the economics involved. Most of the regenerated rubber from tires is a mixture of both saturated and unsaturated synthetic elastomers and natural rubber.

In one embodiment of the invention, aromatic hydrocarbon compositions, including substituted aromatic hydrocarbon compositions, are removed from hydrocarbon mixtures containing both aromatic and aliphatic hydrocarbons and from aqueous mixtures and air or gas streams containing aromatic compounds and aliphatic hydrocarbon compositions. The mixtures may be in a gaseous phase, a liquid phase or a combination of gaseous and liquid phases, and may contain dissolved hydrocarbon solids. The technique can be applied to any such sorbable composition which is not corrosive to or a solvent for the elastomer used to sorb the aromatic hydrocarbon composition.

Examples of useful classes of synthetic elastomer include styrene-butadiene rubber, butyl rubber, nitrile rubber, ethylene-propylene copolymers, fluoroelastomers, polyacrylates, etc. Examples of specifically suitable synthetic elastomers for the selective sorption of aromatics include H -1262 (manufactured by Mercer Rubber Co. of Trenton, N.J.),

which is a mixture of hycar rubber (polyacrylic rubber) and styrene-butadiene rubber; and JH-21 (manufactured by Mercer Rubber Co.), an acrylonitrile elastomer. When the aromatic hydrocarbon compound sought to be removed is benzene, Neoprene (a polychlorobutadiene) and Hypalon (a chlorosulfonated polyethylene elastomer) are not as effective as other synthetic

elastomers insofar as they are partially dissolved by benzene.

The particular synthetic elastomer used in a method will depend on the mixture being treated and the hydrocarbon compositions being removed. Different elastomers may exhibit differences in the degree of absorption among particular hydrocarbons including aromatic hydrocarbons. Furthermore, the sorption capacity of an elastomer is often more selective towards some hydrocarbons than others in the same mixture. For example, when both olefins and aromatics are present, some elastomers will more readily sorb aromatic hydrocarbons compared to olefinic hydrocarbons. Moreover, such elastomers will more easily sorb the aromatic compounds which are more aromatic in character. This is discussed above.

Although the elastomer has the ability to sorb hydrocarbons at atmospheric pressure, the process can also take place under negative pressure or at positive pressure. The pressure at which a particular process is carried out depends on the mixture being treated, e.g. whether it is a gas or a liquid phase. Furthermore, the pressure will be a function of the process economy. The higher the pressure, the more expensive a process becomes. The pressure for a particular sorption process may be the same pressure at which such a process stream normally operates for economic reasons. A gaseous mixture can easily be treated at pressures somewhat greater than atmospheric pressure to the maximum attainable. For example, a hydrogen stream pressurized to 140.6 kg/cm could easily be treated in a manner to maintain the pressure loading of the gas. A liquid mixture is usually processed under a pressure of less than 42.18 kg/cm 2 .

The temperature at which the process is carried out is not critical and can vary over a fairly wide range. For the sake of expediency and for economic reasons, process

the stream's normal temperature is used. As mentioned before

absorption is concentration-gradient driven and as long as the concentration gradient favors the elastomer's absorption, heat tends to enhance the sorption process. Low-quality waste heat can often be used to achieve desired temperature increases.

The degree and rate at which the elastomer has previously been impregnated with a hydrocarbon will also influence its ability to sorb and desorb this or another hydrocarbon. An elastomer that is reused to sorb a hydrocarbon after the hydrocarbon has been desorbed therefrom will often be more effective in terms of

to sorb the hydrocarbon than when it was fresh. Furthermore, an elastomer which has had the opportunity to sorb more of one hydrocarbon than another, e.g. because the sorption has been carried out at a higher temperature, one will desorb at a faster rate than the other, even though desorption of both elastomers is carried out at the same temperature. Temperatures for both sorption and desorption up to between approx. 150 and 260°C, and preferably between approx. 150 and 205°C, for both sorption and desorption effectively increases the elastomer's effectiveness.

The elastomer can be used in the form of sheets, coupons, strips or in another appropriate way. Generally, granular form is preferred, the size of the grains being determined on the basis of process parameters such as acceptable pressure drop in the system and concentration.

After the elastomeric material has contacted the mixture and it has sorbed the hydrocarbon compounds, the elastomeric material can usually be regenerated for further use by desorbing the hydrocarbons therefrom. Subsequently, the desorbed hydrocarbons can usually be easily recovered. Any technique that allows for desorption of the elastomeric material can be used. E.g. the hydrocarbons can usually be desorbed by exposing the elastomeric material to a vacuum or to a heated inert gas, air and/or steam, or a heated carrier gas or water vapour. The hydrocarbon composition desorbed from the elastomeric material can be processed through a condenser to obtain a liquid product or to obtain a more concentrated gas product. The desorption can also take place using a solvent which will remove the hydrocarbon compositions from the elastomeric material or using a displacing agent which will be sorbed by the elastomeric material to thereby displace the hydrocarbon composition which has been removed from the mixture. Other conventional techniques known to those skilled in the art for desorption of the hydrocarbon compositions from the elastomeric material may also be used.

In cases where the hydrocarbon is not readily desorbed or where there is no economic incentive to do so, the enriched elastomer may be burned to recover its heating value or simply encapsulated by appropriate means and buried. Where highly toxic hydrocarbons have been sorbed, desorption may not be desired.

Not only is the present process useful for removing hydrocarbons from hydrocarbon streams or mixtures, it is also useful for removing such compositions from air, gas, vapor or aqueous streams. Waste water from industrial processes containing hydrocarbons including substituted hydrocarbons and such exhibiting water solubility can be purified by bringing the waste water into contact with an elastomer. The process is useful for removing aromatic substances such as benzene, toluene and anthracenes from wastewater and for removing phenols, chlorinated benzenes, nitrophenols, pesticides, insecticides, other toxic substances such as PCBs, and a wide range of other hydrocarbon types. The process can also be used to clean air streams and exhaust gases from industrial processes.

An elastomer can also be used to change the relative concentrations of hydrocarbons in a hydrocarbon stream or mixture. Many elastomers more readily sorb aromatic hydrocarbons that have a greater aromatic character compared to those with less aromatic character, other parameters such as substituents being held constant. Thus, by allowing an aromatic hydrocarbon mixture to come into physical contact with such an elastomer for a very short period of time, the more aromatic hydrocarbons can be selectively sorbed. For the purposes of this discussion, benzene is considered to have the most aromatic character. The aromaticity of an aromatic hydrocarbon decreases as the number of rings increases; thus naphtha is less aromatic in character than benzene, but more aromatic than anthracene. The closer a hydrocarbon compound is in its structure and properties to benzene, the more aromatic its character. Generally, aromaticity also decreases with alkylation. Thus, toluene is less aromatic than benzene and xylene is less aromatic than toluene. It should of course be understood that these are only general principles and that preliminary testing to determine the sorption capacity of the particular elastomer to be used for the particular hydrocarbon composition to be removed under varying conditions of time, pressure, temperature and other parameters should be carried out prior to the present method get specific applications, and such testing may reveal exceptions to the above general principles. Examples of such preliminary test methods are those described in applicant's concurrent application U.S. Pat. Serial No. 06/054,690 directed to "Measuring The Aromatic Reactivity Of A Hydro-carbon Composition". Many hydrocarbon compounds are more readily sorbed than benzene, including but not limited to several halogenated hydrocarbons, several mono-ketones, ethers, amines, aldehydes, amides, nitro compounds, and nitrogen and sulfur heterocyclics. As certainly as the examples herein illustrate, certain generalizations can be made in correlating various properties of hydrocarbons with sorbability. For example, in each hydrocarbon class, molecular weight generally correlates with weight gain inversely for liquids and directly for gases. Where such generalizations apply, process parameters for specific applications can be calculated. Otherwise, preliminary testing to determine the sorption capacity of the particular elastomer for the particular hydrocarbon should be done before the present method is used for specific applications.

When the elastomer used has a greater ability to sorb saturated or olefinic, aliphatic compounds, it can of course be used for the selective removal of these compounds from mixtures that also contain aromatic substances and thereby increase the mixture's relative aromatic content. Silicone rubber exhibits e.g. a higher affinity for aliphatic saturated compounds than for aromatic substances.

The method according to the present invention can be carried out as a batch operation or continuous operation. The contact time between the mixture being treated and the elastomer is dependent on a number of parameters including the surface area of the elastomer, the allowable system pressure drop, the volume, concentration and processing rate of the mixture being treated, the particular aromatic hydrocarbons and/or aliphatic hydrocarbons being removed, the sorbents of the elastomer -ability of the aromatic or aliphatic hydrocarbon being removed, the particular mixture being treated, including the presence of the solvent which may promote the ability of a particular hydrocarbon to be sorbed by a particular elastomer, and the process economics. All these parameters are associated with a specific process design.

When certain elastomers have less affinity for a particular type of hydrocarbon compound than another, such as those with the most affinity for aromatic compounds, a lesser affinity for olefinic compounds, and the least affinity for saturated compounds, hydrocarbons can be removed from the same mixture using more elastomer and a longer period of time for the process than used for the removal of only aroma

f- "i

tical hydrocarbons. In such cases, it is preferred to use a method which brings the mixture into contact with fresh elastomer more than once. Such a process has the ability to remove the aromatic hydrocarbons first using more than one cycle as needed. Subsequently, the olefinic hydrocarbons may likewise be removed and saturated compounds may be left in the mixture or finally removed depending on the elastomer selected.

Since certain elastomers selectively remove certain types of hydrocarbons, many process combinations will be apparent to those skilled in the art for using different elastomers to sequentially remove different hydrocarbon types, thereby selectively recovering such hydrocarbons or changing the relative proportions of hydrocarbons in the remaining mixture.

Certain solvents promote the ability of hydrocarbons to be sorbed by special elastomers. The ability of solid hydrocarbons to be sorbed is particularly dependent on the solvent in which the solid hydrocarbon is dissolved. Furthermore, certain combinations of hydrocarbons are more easily sorbable than each hydrocarbon alone. E.g. benzene-acetone mixtures are more easily sorbed than each hydrocarbon alone, and ethanol is more easily sorbed as a 75% by volume solution in benzene than alone or in smaller concentrations in the benzene. Such synergistic effects, when discovered by testing, can be easily incorporated into the present method to increase the efficiency of the process.

The method according to the invention can be used to improve the economic conditions of water-alcohol separation as an alternative to distillation. In addition to the synergistic effect for benzene in ethanol removal, certain elastomers such as copolymers of vinylidene fluoride and hexafluoropropylene have been found to be effective for the selective removal of methanol. Other examples of alcohol removal are shown in the examples herein.

Another embodiment of the present invention involves its application to the removal of hydrocarbons from oil shale retort processes, particularly the modified in situ process. Some of the hydrocarbons present in such process water

are very difficult to remove by other means, but are easily sorbed with certain elastomers.

The method according to the invention is useful for recovery

and regeneration of valuable hydrocarbons that would otherwise escape to the environment. For example, when filling tanks with liquid hydrocarbons, vapors present in the empty tank are pushed out. Certain vapors can be sorbed by elastomers such as scrap rubber, and as the liquid level in the tank decreases due to removal of the liquid, the vapors will desorb. In this way, the loss of valuable hydrocarbons can be prevented.

The following examples illustrate the method according to the invention and will suggest other specific applications for the person skilled in the art.

Example 1

Rubber coupons were prepared from samples of H-1262 synthetic elastomer having a thickness between 0.635 and 3.175 mm and divided into strips with a width of 12.7 mm and a length such that each coupon had a weight between 0.7 and 1.0 g. Exactly 25 ml of each liquid to be tested was placed

in separate, numbered 250 ml Erlenmeyer flasks. The numbers on the flasks correspond to the numbers given to the coupons. To each flask a corresponding elastomeric coupon was added, a stopper was tightly fitted and the flask was lightly swirled and set aside for a period of 2 hours at a temperature of 18.33-23.89°C and at ambient pressure. At exactly two hours for each sample and within 30 seconds, the cap was removed, the liquid was discarded, the coupon was shaken out on a paper towel, dried, and the weight of the coupon was obtained to the nearest 0.1 mg. The weight increase for each coupon was calculated as a percentage increase from the original weight. The

liquids tested were 100% n-decane, 100% benzene and varying mixtures of these two liquids. The sorption capacity of the H-1262 elastomer was measured by the amount of weight gain of each elastomer coupon. The results are shown in Table 1.

Example 2

The same techniques as in example 1 were used with the exception that the liquids tested were iso-octane, benzene and mixtures of these two liquids. The elastomeric coupons used were of JH-21 synthetic rubber. The data are set out in Table 2.

Example 3

Using the technique of Example 1, the ability of H-1262 elastomer to sorb various hydrocarbons was measured. The results are given below in table 3.

Example 4

Using the technique of Example 1, 1.60 mm thick silicone rubber coupons from Dupont of Chicago, Illinois (No. SS-5550, 50 duro) were tested for their ability to sorb benzene and iso-octane and various mixtures thereof. The results are shown in table 4.

Example 5

Using the technique of Example 1, various synthetic and natural elastomers were tested for their ability to sorb six liquids. For comparison, each elastomer was also tested for percent weight gain using water. Results are shown in table 5.

Example 6

Using the technique of Example 1, various halogen-substituted aromatic, olefinic and aliphatic hydrocarbons were tested for their ability to be sorbed by JH-21. Results are shown in table 6.

Example 7

Using the technique of Example 1 except that the exposure time of the elastomer was varied as indicated, the sorption capacity of JH-21 for benzene was tested. The results are shown in table 7.

Example 8

Two flasks were prepared, each containing 100 mL of 5.0% by volume benzene in iso-octane. • About 5 g of JH-21 coupons were placed in flask 1, and about 10 g of JH-21 coupons were placed in flask 2. The amount of absorbed benzene was checked after different intervals of elapsed time. Results are shown in table 8.

Example 9

Using the technique of Example 1 except that the exposure time of the elastomer was varied as indicated, various named "mixture components" ("cutters") were tested for their ability to be sorbed by H-1262. "Mixture components" are process distillation fractions in a certain boiling range, which are sold as solvents.

Example 10

Using the technique of Example 1, the sorption capacity of JH-21 for decane and iso-octane was tested. Results are shown in table 10.

Example 11

Two coupons of JH-21 were exposed to 100% benzene for 2 hours, coupon 7#. 1 at 21°C and coupon ?¥ 2 at 48.9°C. At the end of two hours, coupon #1 showed a weight gain of 120.60% and coupon #2 showed a weight gain of 13 6.80% over their original weights. Coupon #1 was then desorbed at 48.9°C and Coupon #2 was desorbed at 21°C, and percent weight gain or loss over the original coupon weights was checked at varying intervals. Results are shown in table 11.

Example 12

Deionized water was saturated with benzene by adding equal parts

of the water and the benzene are in contact with each other for 30

days, with daily mixing, until the calculated solution concentration for benzene was 0.0858 g per 50 ml (1948 ppmv). Coupon #1, a JH-21 coupon, weighing 0.9830 g, was exposed to the saturated benzene solution for varying periods of time, and Coupon #2, a JH-21 coupon weighing 0.9797 g, was exposed to deionized only water for a similar period of time at the same temperature (21°C). At the end of approximately 312 days, coupons #1 and #2 were replaced with coupon #3, weighing 1.1398 g, and coupon #4, weighing 1.1283 g, in benzene and pure water solutions, respectively, to test for complete removal of benzene from water. Results are shown in table 12.

Example 13

To test an elastomer's capacity for growing benzene sorption, coupons 1 through #5, consisting of JH-21, were first allowed to sorb benzene from solutions of varying benzene concentrations. Each coupon was then placed, without desorption, in contact with a 100% benzene solution for two hours, after which benzene was desorbed from each coupon by exposure to air for 36 hours. Results are shown in table 13.

Example 14

The benzene sorption and desorption capacities of JH-21 and H-1262 were tested using coupons of each elastomer against solutions of varying benzene concentrations at ambient temperature, and testing the percent weight gain of each after varying periods of time. Two coupons of each elastomer were used for each benzene concentration. The coupon pairs were then separately desorbed by exposure to air at 21°C and 60°C, respectively, for 2 hours. Results are shown in table 14.

Example 15

The capacity of scrap rubber for reuse in successive sorption-desorption cycles was tested using ground scrap material from a tire-treading operation. This rubber has a high styrene-butadiene content. Particles with a size of +4 mesh (US standard sieve) and particles with a size from 4 to +10 mesh were tested separately. 1 g of each size was soaked in benzene in a stoppered flask for 2 hours and the absorption determined by reweighing. Desorption was carried out by exposure to the air and was controlled at varying intervals. The material was then air-dried for 24 hours before the next cycle was started. Results are shown in table 15.

Example 16

A coupon of H-1262 synthetic elastomer was tested for its ability to be reused in successive sorption-desorption cycles. The method of Example 15 was followed, with the exception that a coupon was used instead of ground and sieved particles of the elastomer. Results are shown in table 16.

Example 17

A coupon of JH-21 synthetic elastomer was tested following the method of Example 16. Results are shown in Table 17.

Example 18

A coupon of Dupont SS-5550 silicone synthetic elastomer was tested following the method of Example 16. Results are shown in Table 18.

Example 19

A coupon of Kirkhill 250B280 Neoprene synthetic elastomer was tested following the method of Example 16. Results are shown in Table 19.

Example 20

A coupon of Kirkhill 550C1958 styrene-butadiene-rubber synthetic elastomer was tested following the method of Example 16. Results are shown in Table 20.

Example 21

A coupon of Kirkhill 560C2935 styrene-butadiene-rubber synthetic elastomer was tested following the method of Example 16. Results are shown in Table 21.

Example 22

Conditions under which polychlorinated biphenyls (PCBs) are sorbed were tested using coupons of JH-21. Pyranol, an askarel-type PCB manufactured by General Electric Company, was contacted as a 100% solution

and as a 50/50 pyranol-benzene mixture at varying temperatures for 2 hours, then desorbed by exposure to air. After 26 hours of desorption in test 3, the temperature was lowered from 110°C to 24°C. Results are shown in table 22.

Example 23

Retort water from a modified in situ oil shale retort was filtered and then passed through a 2.54 cm diameter absorption column containing 10 mesh (US standard sieve) ground tire scrap rubber to a depth of 68.58 cm, the rubber having a total weight of 103.5 g. The surface velocity through the column was approximately 7.11 cm per minute. The benzene aromatic equivalent (BAE) test (according to the method in US serial no. 06/273,850) and a method 502A gravimetric freon extraction were carried out on feed seal water after filtration and on the product water. Results are shown in table 23.

Example 24

The effect of different solvents on the sorbability of several solid chemicals dissolved therein, as measured by the benzene aromatic equivalent (BAE) of each mixture, was tested by mixing the solid chemicals and solvents in the proportions shown in Table 24. Results are shown in table 24.

Example 2 5

The effect of different solvents on the sorbability of a liquid (Dalton mixture component), thus mixtures, as measured by the benzene aromatic equivalent (BAE) of each mixture, was tested by mixing the Dalton mixture component with the solvents in those in table 25 indicated quantity ratios. Results are shown in table 25.

Example 26

Certain combinations of chemicals give rise to synergistic effects on absorbability. Several combinations were tested following the method in Example 25. Results, expressed as percent weight gain and BAE, are given in Table 26.

Example 27

To test the ability of various elastomers to sorb hydrocarbons in the gaseous phase, coupons of various elastomers were suspended in a corked Erlenmeyer flask. Hydrocarbon gas was pumped into the flask through a tube that passed through an inlet in the cork and stretched to the bottom of the flask. An outlet in the cap allowed venting of gas to the outside. The coupons were removed and weighed at intervals as indicated in Table 27. The test method was varied in the case of pentane. In this case, the coupon was suspended in the vapor space above the surface of 25 mL of liquid pentane. The pentane vapor was in equilibrium with air at 21°C and barometric pressure 628.52 mm Hg. For comparison, coupons were also immersed in liquid pentane. Results are shown in table 27.

Example 28

The effects of pre-leaching on an elastomer's ability to sorb different hydrocarbon types were tested by pre-leaching certain elastomers with different solvents, and the percent capacity increase was calculated. Results are shown in table 28.

Example 29

The potential for pre-leaching with certain solvents to increase the sorption and desorption capacity of JH-21 for various hydrocarbon types was tested as shown in Table 29. Solvents showing air desorption weight loss from original were considered to have high potentials. Results are shown in table 29.

Example 30

To test the ability of various elastomers to sorb and desorb gasoline vapors displaced from storage or fuel tanks during filling, 1.0 g coupons of various elastomers that had been pre-leached with pentane were exposed to vapors from a leaded regular gasoline of summer quality that had been stored in an atmospherically aerated jerry can for 6 months. For comparison, coupons of each elastomer were also exposed to the liquid gasoline. Results are shown in Table 30. From the above it is clear that the method according to the present invention for removing hydrocarbons can be used in a large number of specific applications, including purification of process streams, separation of hydrocarbons, change of relative hydrocarbon concentrations, recovery of hydrocarbons which will otherwise be lost to the surroundings; safe disposal of toxic hydrocarbons, and other uses that will be apparent to the person skilled in the art.

Claims (22)

1. Method for removing at least one hydrocarbon composition from a mixture containing said hydrocarbon composition, characterized in that the mixture is brought into contact with at least one elastomer at least once under conditions which cause the elastomer to sorb at least part of the hydrocarbon composition. 2. Method according to claim 1, characterized in that the elastomer used is selected from the group consisting of natural rubber, scrap rubber and synthetic elastomers. 3. Method according to claim 1, characterized in that the hydrocarbon composition is desorbed from the elastomer. 4. Method according to claim 1, characterized in that the hydrocarbon composition is not desorbed. 5. Method according to claim 3, characterized in that the elastomer is used again in at least two successive sorption-desorption cycles. 6. Method according to claim 3, characterized in that the desorbed hydrocarbon composition is recovered. 7. Method according to claim 1, characterized in that substantially all of at least one hydrocarbon composition is removed from the mixture, which results in a mixture that has been purified of the hydrocarbon composition (e). 8. Method according to claim 1, characterized in that the relative concentration of different hydrocarbons in a mixture containing said hydrocarbons is changed by bringing the mixture into contact with an elastomer under conditions which cause the elastomer to selectively sorb at least a part of at least one of the hydrocarbons present in the mixture and the resulting altered mixture is recovered. 9. Method according to claim 1, characterized in that the hydrocarbon mixture comprises at least two different hydrocarbon compositions selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, olefinic hydrocarbons and saturated hydrocarbons, and that at least part of one of said hydrocarbon compositions is removed. 10. Method according to claim 1, characterized in that the hydrocarbon composition that is removed is a substituted hydrocarbon composition. 11. Method according to claim 1 or claim 6, characterized in that the hydrocarbon composition that is removed is an alcohol. 12. Method according to claim 1 or claim 7, characterized in that the hydrocarbon composition that is removed is a toxic substance. 13. Method according to claim 1, characterized in that the mixture containing the hydrocarbon composition (é) is in the liquid phase. 14. Method according to claim 1, characterized in that the mixture containing the hydrocarbon composition (e) is in the gaseous phase. 15. Method according to claim 1, characterized in that at least one hydrocarbon composition is a solid, and that the mixture contains a solvent for said solid. 16. Method according to claim 1, characterized in that a selected solvent in a selected quantity is added to the hydrocarbon mixture in order to maximize the ability of the hydrocarbon composition to be sorbed by the elastomer. 17. Method according to claim 13, characterized in that the mixture containing the hydrocarbon compositions is waste water from an oil shale retort process. 18. Method according to claim 1, characterized in that the composition of another hydrocarbon mixture is changed by selectively extracting desired hydrocarbons from the first hydrocarbon mixture and adding said extracted hydrocarbons to said second hydrocarbon mixture to change its composition. 19. Method according to claim 18, characterized in that the octane number of the second hydrocarbon mixture is increased by selectively extracting aromatic hydrocarbons from the first hydrocarbon mixture and adding said aromatic hydrocarbons to said second hydrocarbon mixture to increase its octane number. 20. Method according to claim 1, characterized in that the hydrocarbon composition comprises vapors that are displaced from a tank during filling of the tank with a liquid hydrocarbon. 21. Method according to claim 1, characterized in that the elastomer is prewashed with at least one solvent chosen to increase its capacity to adsorb at least one hydrocarbon composition before it is used for this. 22. Method according to claim 1 or claim 21, characterized in that the sorption and/or desorption is carried out at a temperature between approx. 150°C and approx. 260°C to increase the sorption and/or desorption rate.