WO2001034539A1

WO2001034539A1 - Method of saturating olefins

Info

Publication number: WO2001034539A1
Application number: PCT/US2000/014512
Authority: WO
Inventors: Jeffrey H. Sherman; James W. Hershberger
Original assignee: Miami University
Priority date: 1999-05-29
Filing date: 2000-05-25
Publication date: 2001-05-17
Also published as: AU4133301A

Abstract

A process for saturating olefins and alkynes in a hydrocarbon stream comprises mixing the hydrocarbon stream with a surfactant, hydrazine and an oxidizer. The resulting mixture is then directed through an ion exchange resin including a catalyst, preferably a copper (II) catalyst. Mixing of the hydrazine and the oxidizer in the presence of the catalyst forms diimide which saturates the olefins and the alkynes in the hydrocarbon stream.

Description

METHOD OF SATURATING OLEFINS

TECHNICAL FIELD

This invention relates generally to a method of olefin saturation, and more

particularly to an uncomplicated, economical, and safe method which achieves total

olefin saturation.

BACKGROUND AND SUMMARY OF THE INVENTION

Hydrocarbons having a carbon-carbon double bond are known as olefins.

Hydrocarbons having a carbon-carbon triple bond are known as alkynes. Olefins and

alkynes are inherently unstable, and when present in lubricating oils, fuels, etc., often

spontaneously polymerize or otherwise react to form sludge and other contaminants.

The process of placmg two hydrogen atoms across a carbon-carbon double bond or four

hydrogen atoms across a carbon-carbon triple bond is known as olefin saturation or

hydrogenation. Hydrogenation changes an olefin and/or an alkyne to an alkane. Since

alkanes are inherently more stable than olefins or alkynes, the saturation of all olefins

and alkynes present in lubricating oils, fuels, etc., is highly desirable.

Olefin and alkyne saturation is also desirable in other circumstances. Ethylene

is the simplest and most prevalent of the olefins. Ethylene is used in the manufacture

of polyethylene which is the most prevalent of the plastics. Following polymerization,

it is desirable to saturate any remaining olefins.

Another circumstance in which olefin saturation is desirable is in the

manufacture of synthetic lubricants, such as polyalphaolefins. In manufacturing

polyalphaolefins, alphaolefins are reacted with each other to form compounds of two or

more alphaolepfins known as oligomers. Once formed, the oligomer often contains a

residual carbon-carbon double bond which must be saturated.

The objective of olefin saturation has been accomplished in the past, but only by

means of complicated, expensive, and inherently dangerous operations. Co-pending application serial no. 09/418,447 filed October 19, 1999, and

assigned to the assignee hereof discloses a method of olefin saturation in which a

hydrocarbon stream including olefins and/or alkynes is treated with hydrazine and

hydrogen peroxide in the presence of a catalyst. Preferably, the catalyst comprises a

copper salt. The method also involves the use of a surfactant which serves to increase

the surface area of the oil/water interface. Following the reaction, the surfactant is

removed.

Although generally successfully in practice, the method of co-pending

application serial no 09/418,447 involves certain difficulties.

Diimide is produce through the interaction of hydrazine with a copper (II) salt

catalyst. Once formed, the diimide is capable of selectively saturating certain multiple

bonds between carbon atoms and between carbon and other atoms. Unfortunately, a

diimide species is also capable of interacting with another diimide species to regenerate

hydrazme and nitrogen. Thus, hydrazine is typically required in much greater than

stoichiometric amounts to ensure adequate reaction of diimide with an olefinic system.

However, the addition of greater amounts of hydrazine is of diminished value as the

occurrence of the undesirable diimide-diimide reaction is rendered more probable. An

alternative to the addition of a large excess of hydrazine is to run the reaction over a

longer period of time by slowly delivering hydrazine into the reaction medium.

The present invention consists of immobilizing the copper catalyst on a cation

exchange resin. While several cation exchange resins are suitable, the preferred resin is a highly cross-linked polymeric resin that has been derivatized to include a large

number of sulfonic acid sites, for example, poly (styrene-divinylbenze) resin. The high

cross-lmking of the resin serves to prevent the resin from swelling in the presence of the

emulsion. The capacity of the resin, that is the number of sulfonic acid exchange sites,

may be varied to ensure proper wetting by the emulsion. Likewise, the strength of the

emulsion may be varied so as to complement the resin capacity to ensure proper wetting.

While the resin maybe simply suspended in solution, the preferred embodiment

of the invention uses a cation exchange resin packed into a column, through which a

preformed emulsion is pumped. The preformed emulsion consists of the organic

medium containing the unsaturated species, water, hydrazine and an inexpensive

surfactant, preferably an anionic surfactant.

Another advantage of our invention over that of the prior art is the ability of the

resin to contain a relatively large amount of the copper catalyst. Larger amounts of the

copper catalyst result in a very short reaction time without suffering the diimide-diimide

reaction problem previously described.

Air or another oxidizing reagent, such as hydrogen peroxide, may be added to

the emulsion. The oxidizing reagent serves to continuously regenerate the copper (II)

catalyst, which is reduced to copper (I) upon the formation of diimide.

Yet another advantage of the invention results from use of the preferred

embodiment of the invention wherein the reaction takes place in a column packed with

the ion exchange resin. In accordance with the preferred embodiment the resin is in the form of beads, ranging in size rom 5 to 100 microns or greater, whi-.h serves to generate

highly turbulent flow in the dehvered emulsion. The turbulent flow allows the superior

contact between the generated diimide and the species to be saturated, resulting in even

faster reaction times. Additionally, the turbulent flow reduces the required amount of

surfactant leading to an emulsion that is easily broken in a clarifier that receives the

emulsion following its residence in the packed column.

After clarification, the aqueous phase of the broken emulsion is recycled for use

with additional organic material contaminated by the unsaturated species, while the

organic phase of the broken emulsion can be processed further, for example by distillation or extraction.

The invention is particularly suited for the recovery of distillate fueis that have

aged and degraded beyond the point of safe utilization. When distillate fuels, especially

those that have not been subjected to refinery processes such as reforming or alkylation,

are stored, contaminants such as olefins, organic peroxides, water and bacteria tend to

collect. If aged fuel is used in an engine, the engine may be severely damaged.

Obviously, this is an undesirable result, especially when the fuel is used in aviation

engines.

Unfortunately, many distillate fuels, especially those destined for military use,

are stored to the point at which they are no longer usable. Removing water and bacteria

from aged fuel is easily accomplished through distillation. However, olefins and organic peroxides that form in aged fuel are not easily removed through the distillation

method.

Subjecting aged fuel to treatment through the saturation method of the present

invention removes organic peroxides, olefins, and alkynes from the fuel. The saturation

methodology is easily practiced in a continuous process prior to the ultimate distillation

of the fuel.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention may be had by

reference to the following Detailed Description when taken in conjunction with the

accompanying Drawings wherein:

FIGURE 1 is a diagrammatic illustration of the formation of diimide from hydrazine and air or oxygen;

FIGURE 2 is a diagrammatic illustration of the formation of diimide from

hydrazine and hydrogen peroxide;

FIGURE 3 is a diagrammatic illustration of the saturation of olefins by diimide;

FIGURE 4 is a diagrammatic illustration of copper (II) absorbed on sulfonated polystyrene to form at cation exchange resin;

FIGURE 5 is a diagrammatic illustration of an apparatus for saturating olefins

and alkynes incorporating the method of the present invention; and

FIGURE 6 is a partial sectional view comprising an enlargement of a portion of

FIGURE 5.

DETAILED DESCRIPTION

As is well known, olefins and alkynes are extremely unstable chemically and are

capable of spontaneous polymerization. The presence of olefins and/or alkynes in

hydrocarbon streams therefore results in the formation of sludge and other undesirable

contaminants. Olefin and alkyne removal is therefore extremely useful in the treatment

of fuels, lubricating oils, and the like, wherein the presence of sludge and similar

contaminants is highly undesirable.

The present invention comprises a method of adding hydrogen across carbon-

carbon double or triple bonds in a large variety of hydrocarbon streams. In this manner,

hydrocarbons of the classes known as olefins or alkynes are transformed into

hydrocarbons of the class known as alkanes. The process of adding hydrocarbons to

olefins or alkynes is known as saturation or hydrogenation, and the present invention is

successful in achieving total saturation of olefins and alkynes.

The process of the invention utilizes hydrazine and an oxidizer in slightly higher

than stoichiometric amounts, and a metallic salt in catalytic quantities. Additionally, the

process employs a small amount of a selected surfactant to generate a weak water-in-oil

emulsion. In the emulsion, the catalyst resides at the oil/water interface, and the reaction

therefore takes place at the oil/water interface.

The present invention further consists of immobilizing the copper catalyst on a

cation exchange resin. While several cation exchange resins are suitable, the preferred

resin is a highly cross-linked polymeric resin that has been derivatized to include a large number of sulfonic acid sites such as poly (styrene-divinylbenzon) resin. The high

cross-linking of the resin serves to prevent the resin from swelling in the presence of the

While the resin may be simply suspended in solution, the preferred embodiment

of the invention uses a cation exchange resin packed into a column through which a

preformed emulsion is pumped. The preformed emulsion consists of the organic

medium containing the unsaturated species, water, hydrazine and an inexpensive

surfactant, preferably an anionic surfactant.

Another advantage of the present invention over that of the prior art is the ability

of the resin to contain a relatively large amount of the copper catalyst. Larger amounts

of the copper catalyst result in a very short reaction time without suffering the diimide-

diimide reaction problem previously described.

Air or another oxidizing reagent, such as hydrogen peroxide, may be added to

catalyst, which is reduced to copper (I) upon the formation of diimide.

Yet another advantage of the invention results from use of the preferred

the ion exchange resin. In accordance with the preferred embodiment of the invention,

the resin is in the form of beads, ranging in size rom 5 to 100 microns or greater, which serves to generate highly turbulent flow in the delivered emulsion. The turbulent flow

allows the superior contact between the generated diimide and the species to be

saturated, resulting in even faster reaction times. Additionally, the turbulent flow

reduces the required amount of surfactant, leading to an emulsion that is easily broken

in a clarifier that receives the emulsion following its residence in the packed column.

with additional organic material contaminated by unsaturated species, while the organic

phase of the broken emulsion can be processed further, for example by distillation or

extraction.

Examples of catalysts which may be utilized in the practice of the invention

include all salts with copper, particularly including copper sulfate and copper chromate,

and salts of iron, ruthenium, osmium, cobalt, and nickel. Examples of oxidizers which

may be utilized in the practice of the invention include hydrogen peroxide, aqueous

hydrogen peroxide in any concentration, organic peroxides including t-butyl

hydroperoxide and peroxybenzoic acid, oxygen, and air.

Examples of surfactants that may be utilized in the practice of the invention

include sodium dodecyl sulfate (SDS), sodium stearate, potassium stearate, lauroyl

ethylenediaminetriacetic acid, salts of ethylenediaminetriacetic acid, all other anionic

surfactants, cetyltrimethylammonium chloride, all other cationic surfactants, all

zwitterionic surfactants including sulfobetaines. Surfactant systems composed of mixtures of two or more surfactants may also be used. The optimum concentration range for a copper salt catalyst is 0.1 - 5.0 ppm

(w/w) where a non-chelating surfactant such as sodium dodecyl sulfate, sodium stearate,

or potassium stearate is employed. Where a chelating surfactant such as lauroyl

ethylenediaminetriacetic acid is employed, the optimum catalyst concentration is in the

range of 10 - 100 ppm. Concentrations as low as 0.001 ppm and as high as 1000 ppm

may be useful, depending on the requirements of particular applications of the invention. In applications of the invention where a cation exchange resin is employed, the catalyst

concentration is substantially equal to the capacity of the resin.

Concentrations of emulsions are optimal for oi water weight ratios in the range

10:90 to 90:10. However, ratios as low as 1 :99 and as high as 99:1 may be used in

particular applications of the invention. The weight percent of surfactant is optimal in

the range 0.01 - 5.0. However, concentrations of surfactant as high as 20 weight percent

or as low as 0.0001 weight percent may be used depending upon the requirements of

particular applications of the invention.

The amount of hydrazine used is determined by the amount of olefin to be

saturated. Mole ratios (hydrazine:olefin) in the range 1.5:1.0 to 10.0:1.0 are optimal,

however ratios as low as 1.0:1.0 and as high as 1000: 1.0 may be used, again depending

on the requirements of particular applications of the invention. The amount of oxidizer

used is determined by the amount of hydrazine used. Mole ratios (oxidizeπhydrazine)

in the range 1.0: 1.0 to 2.0: 1.0 are optimal, but higher ratios may also be used. A more complete understanding of the invention may be had by reference to the

drawings. Figure 1 illustrates the formation of diimide from hydrazine and air for

oxygen. Figure 2 illustrates the formation of diimide from hydrazine and hydrogen

peroxide. Figure 3 illustrates the saturation of olefins by diimide. Figure 4 illustrates

the key to the present invention which is the absorption of copper (II) ions on a

sulfonated polymer, such as polystyrene to form a cation exchange resin.

Referring to Figure 5, a system for recovering aged fuels 10 comprising a

preferred embodiment of the invention is shown. Aged fuel from a source 12 is directed

through a pump 14 and a heater 16 to a first static mixer 18. A surfactant is directed

from a source 22 through a pump 24 to the static mixer 18 wherein it is thoroughly mixed with the aged fuel.

Hydrazine is directed from a source 28 through a pump 30 to a second static

mixer 32. The fuel/surfactant mixture comprising the output from the first static mixer

18 is also directed to the second static mixer 32 wherein the hydrazine is thoroughly

mixed into the fuel surfactant mixture.

An oxidizer such as hydrogen peroxide, an organic peroxide, oxygen, or air is

directed from a source 36 through a pump 38 to a third static mixer 40. The

fuel/surfactant/hydrazine mixture comprising the output of the second static mixer 32

is also directed to the third static mixer 40 wherein the oxidizer is thoroughly mixed into the fuel/surfactant/hydrazine mixture. In heu of the oxidizer source 36, the pump 38, and the ->.atic mixer 40, the

emulsion from the second static mixer 32 may be directed through a micronizer 44

which entrains sub-micron size bubbles of a gaseous oxidizer received from a source 45

into the emulsion. The micronizer 44 may be similar to that disclosed in U.S. patent

number 5,954,925. Other commercially available micronizers may also be used in the

practice of this invention.

Either the emulsion from the third static mixer 40 having the oxidizer from the

source 36 mixed therein or the emulsion from the micronizer 44 having sub-micron size

oxidizer bubbles entrained therein is directed through a column 46 which is packed with

an ion exchange resin including a catalyst. For example, the resin may be copper (II)

absorbed on polystyrene. Other catalysts and other polymers may be used in the

practice of the invention depending upon the requirements of particular applications of

the invention. The ion exchange resin is initially charged and is recharged as necessary

by directing a catalyst solution from a source 46 through a pump 48 through the

polymeric material within the column 46.

The column 46 is further illustrated in Figure 6. The ion exchange resin is

preferably in the form of beads 49. The beads 49 preferably have an average diameter

of between about 5 microns and about 100 microns or larger.

Referring momentarily to Figures 1, 2, and 3, the foregoing steps of the method

of the invention results the formation of diimide, which in turn saturates the olefins and al ynes ^contained in the liquid hydrocarbon. The oxidizer in the emulsion regenerates

the copper (II) catalyst which is reduced to copper (I) upon the formation of the diimide.

Referring again to Figure 5, the fuel/surfactant/hydrazine/oxidizer mixture

comprising the output of the column 46 is directed to a clarifier 50 wherein the fuel is

separated from most of the water, the surfactant, residual hydrazine, and residual

oxidizer agent. The fuel is directed through a pump 52 and a heater 54 to a flash drum

56 which removes any remaining water from the fuel through an outlet 58. From the

flash drum 56 the dehydrated fuel is directed through a pump 62 and a heater 64 to an

evaporation column 66 wherein the fuel is separated into still bottoms which are recovered through an outlet 68 and one or more fuel components which are recovered

through outlets 70, 72, etc. Part of the still bottoms are recirculated through a pump 74

and the heater 64 to the evaporation column 66 while the remainder of the still bottoms

are recovered through an outlet 76 for utilization as an asphalt modifier, etc.

The non-fuel liquid that is removed from the clarifier 50 comprises a mixture of

water, surfactant, residual hydrazine, and residual oxidizer. The no n- fuel mixture is

directed to a reverse osmosis unit 80. The surfactant, residual hydrazine, and residual

oxidizer are directed through a recirculation loop 82 to the second static mixer 32,

thereby substantially reducing the amount of surfactant, hydrazine, and oxidizer that is

necessary in the operation of the system 10. Water is recovered from the reverse

osmosis unit 80 through an outlet 84 and is suitable either for direct discharge or for

further processing, for example, in a water treatment plant. Depending upon the amount of fuel to be processed, the entire system 10 may

be mounted on a truck, trailer, or similar vehicle for transportation from location to

location. Transportability of the system 10 is highly advantageous in that aged fuels

requiring processing are typically stored in finite supplies at multiple locations.

Although preferred embodiments of the invention have been described in the

foregoing Detailed Description, it will be understood that the invention is not limited

to the embodiments disclosed, but is capable of numerous rearrangements,

modifications, and substitutions of parts and elements without departing from the spirit

of the invention.

Claims

Clairns

1. A method of removing contaminants from aged fuel including the steps

of: providing aged fuel;

providing an ion exchange resin including a catalyst;

mixing a surfactant, hydrazine, and an oxidizer with the aged fuel in

accordance with first, second, and third predetermined ratios, respectively, thereby

forming an emulsion;

directing the resulting emulsion through a quantity of the ion exchange

resin; separating water, surfactant, remaining hydrazine, and remaining oxidizer

from the treated fuel; and

distilling the treated fuel to separate still bottoms therefrom.

2. The method according to Claim 1 wherein the mixing step is

characterized by mixing a surfactant selected from the group including anionic, cationic, and zwitterionic surfactants with the aged fuel.

3. The method according to Claim 1 wherein the step of providing an ion

exchange resin including a catalyst is further characterized by providing an ion exchange

resin including a metallic catalyst.

4. The method according to Claim 3 wherein the step of providing an ion

exchange resin including a metallic catalyst is further characterized by providing an ion exchange resin including a copper salt.

5. The method according to Claim 1 wherein the mixing step is

characterized by mixing an oxidizer comprising hydrogen peroxide with the aged fuel.

6. The method according to Claim 1 wherein the mixing step is

characterized by mixing an oxidizer comprising oxygen with the aged fuel.

7. The method according to Claim 1 wherein the mixing step is characterized by mixing an oxidizer comprising air with the aged fuel.

8. The method according to Claim 1 including the additional step of

separating the water from the separated surfactant/hydrazine/oxidizer mixture.

9. The method according to Claim 8 including the additional step of

recycling the surfactant/hydrazine/oxidizer mixture and thereby reducing the amounts

of surfactant, hydrazine, and oxidizer which are required in the practice of the method.

10. The method according to Claim 1 wherein the distillation step is further

characterized by separating the treated fuel into still bottoms and at least one type of

treated fuel.

11. The method according to Claim 1 wherein the mixing step is further

characterized by: mixing the surfactant, hydrazine, and aged fuel to form an emulsion; and

directing the emulsion through a micronizer which entrains sub-micron

size bubbles of oxidizer in the emulsion.

12. A method of recovering aged fuel comprising the steps of: providing aged fuel;

providing an ion exchange resin including a catalyst;

mixing surfactant with the aged fuel in accordance with a first predetermined ratio;

mixing hydrazine with the resulting aged fuel/surfactant mixture in accordance with a second predetermined ratio;

mixing an oxidizer with the resulting aged fuel/surfactant/hydrazine

mixture in accordance with a third predetermined ratio;

directing the aged fuel surfactant/hydrazine/oxidizer mixture through a quantity of the ion exchange resin; and

separating the treated fuel from the surfactant/remaining

hydrazine/remaining oxidizer mixture.

13. The method according to Claim 12 wherein at least one of the mixing steps is carried out in a static mixer.

14. The method according to Claim 12 wherein the aged fuel is heated prior to the first mixing step.

15. The method according to Claim 12 wherein the step of separating the

treated fuel from the surfactant/remaining hydrazine/remaining oxidizer mixture is

carried out in a clarifier.

16. The method according to Claim 12 including the additional step of

direciing the treated fuel through a flash drum and thereby removing any residual water

from the treated fuel.

17. The method according to Claim 16 including the additional step of

directing the dehydrated treated fuel to an evaporator column and thereby separating still bottoms from the treated fuel.

18. The method according to Claim 17 wherein the evaporator column also

separates the treated fuel into light distillate fuel and heavy distillate fuel.

19. The method according to Claim 12 including the additional step of

removing water from the svrfactant/remaining hydrazine/remaining oxidizer mixture.

20. The method according to Claim 19 including the additional step of

mixing the dehydrated surfactant/remaining hydrazine/remaining oxidizer mixture into

the aged fuel surfactant mixture resulting from the first mixing step.

21. The method according to Claim 12 mcluding the additional steps of:

dehydrating the treated fuel;

distilling the dehydrated treated fuel to remove still bottoms therefrom;

dehydrating the surfactant/remaining hydrazine/remaining oxidizer

mixture after the separation of the treated fuel therefrom; and

mixing the dehydrated surfactant/remaining hydrazine/remaining oxidizer

mixture into the aged fuel/surfactant mixture resulting from the first mixing step.

22. The method according to Claim 12 wherein the mixing step is further

characterized by entraining an oxidizer into a mixture comprising aged fuel, surfactant,

and hydrazine.

⁹ . A process for recovery of aged distillate fuels comprising the steps of:

mixing a first predetermined quantity of aged distillate fuel with a second

predetermined quantity of a surfactant, a third predetermined quantity of hydrazine, and

a fourth predetermined quantity of an oxidizer;

directing the aged fuel surfactant hydrazine/oxidizer mixture through an

ion exchange resin including a catalyst and thereby removing olefins, alkynes, and

organic peroxides from the fuel;

directing the foregoing mixture to a clarifier thereby separating water,

surfactant, residual hydrazine, and residual oxidizer from the fuel;

directing the treated fuel to an evaporation column and thereby separating

the treated fuel into still bottoms and at least when usable distillate fuel;

separating water from the surfactant, residual hydrazine, and residual

oxidizers; and reusing the surfactant, residual hydrazine, and residual oxidizer in the

process.

24. The process of Claim 23 wherein the mixing step is further characterized

by entraining sub-micron size bubbles of an oxidizer into a mixture comprising aged

fuel, surfactant, and hydrazine.