WO2007039083A1

WO2007039083A1 - A process for breaking emulsions or preventing emulsion formation

Info

Publication number: WO2007039083A1
Application number: PCT/EP2006/009059
Authority: WO
Inventors: Peter Ernst Froehling
Original assignee: Dsm Ip Assets B.V.
Priority date: 2005-09-20
Filing date: 2006-09-18
Publication date: 2007-04-12

Abstract

Process for contacting a mixture of water and oil with a hyperbranched polyester. In the process the formation of an emulsion is prevented. If before the contacting an emulsion was formed, the emulsion is broken. The process is very suitable to be applied during the winning or transportation of crude oil.

Description

A PROCESS FOR BREAKING EMULSIONS OR PREVENTING EMULSION

FORMATION

The invention relates to a process for breaking emulsions containing oil and water, and also the prevention of the formation of such emulsions.

In many types of industrial processes the unintended formation of emulsions presents a major problem. Undesired emulsions may arise in e.g. liquid- liquid extractions, processes for organic synthesis, wastewater treatment, biotechnological fermentations and the production of mineral oil. Emulsions can be disadvantageous in e.g. technical, economical or ecological aspect. They may have a viscosity, which is much higher than those of the component phases, which necessitates an increased energy need in pumping or mixing. Corrosion of transport lines or storage vessels may occur due to the presence of e.g. emulsified salt water. Ecological problems may arise due to the presence of emulsified organic components in waste water. Product losses due to emulsification can be an economic disadvantage. Emulsions contain two phases: a continuous phase and a dispersed phase. One component phase is always water, which may contain other dissolved compounds such as salts, solvents or other water-soluble entities. The other phase is often denoted as "oil", and is immiscible with water. Examples of "oil" in this sense are: natural petroleum, liquid hydrocarbons, chloro- and fluorohydrocarbons, silicones and vegetable or animal oils or fats. When the continuous phase of the emulsion consists of water, the emulsion is known as an oil-in-water emulsion. When the continuous phase consists of oil, the emulsion is called a water-in-oil emulsion. The relative volume fraction of oil in an emulsion can vary between less than 1 % to over 99 %. Undesirable emulsions can be separated into their component phases by a number of methods. The separation process is generally known as "emulsion breaking". Examples of emulsion breaking methods are centrifugation, filtration, heating or cooling. For example, these methods are described in the book "Emulsions, theory and practice" by P. Becher (Oxford University Press, 2001). An especially relevant method to break an emulsion is contacting a polymeric compound, which can cause emulsion breaking with the mixture of water and oil. It is also possible to contact a mixture of water and oil with a demulsifier, which mixture is not an emulsion. In this case the formation of the emulsion is prevented. Such polymers are known as "demulsifiers". Examples of demulsifiers in current industrial use are e.g. block copolymers of polyethylene glycol and polypropylene glycol, polyethoxylated alkylphenols, ethoxylated alkylphenol-formaldehyde resins, polyvinylalcohol derivatives and cationic or anionic polyelectrolytes. Mixtures of different types of polymers are also used. However, conventional demulsifiers have certain disadvantages. They can be non-biodegradable, which hinders their application e.g. in wastewater treatment or in offshore oilfield applications. Another disadvantage of certain phenolic demulsifiers is their suspected interference with the human endocrine system. Other demulsifiers are toxic against water organisms. Moreover, there exists no general solution for industrial emulsion problems, and there is a continuous need for new products, which can be active as emulsion breakers.

Accordingly, it is the object of the present invention to provide a process for contacting a mixture of water and oil with a demulsifier, to break the emulsion or to prevent the formation of the emulsion, which process does not possess the above-named disadvantages. The object has been accomplished according to the present invention with a process of contacting a hyperbranched polyesteramide, which is a polycondensate of a di-or trialkanolamine and a cyclic anhydride, with a mixture of water and oil.

Surprisingly it has been found that the process according to the present invention is very effective and can be excecuted with low amounts of non-toxic hyperbranched polyesteramides.

One aspect of the present invention is to provide a process in which hyperbranched polyesteramides are used to break a water/oil emulsion. Another aspect of the present invention is to provide a process in which hyperbranched polyesteramides are used to prevent emulsion formation.

According to a preferable example of the present invention, the mixture may comprise an emulsion of water and oil, and the emulsion is broken into water and oil phases when the emulsion contacts with the hyperbranched polyesteramide. According to a preferable example of the present invention, the hyperbranched polyesteramide may be added to the emulsion of water and oil.

According to another preferable example of the present invention, the hyperbranched polyesteramide may be added to the water or the oil phase, before the water and the oil phase are mixed. The hyperbranched polyesteramide is a polycondensate of a di-or trialkanolamine and a cyclic anhydride.

The cyclic anhydride may be preferably selected from the group consisting of succinic anhydride, Ci-Ci₈ alkylsuccinic anhydrides, Ci-Ci₈ alkenylsuccinic anhydrides, polyisobutenylsuccinic anhydride, phthalic anhydride, cyclohexyl-1 ,2- dicarboxylic anhydride, cyclohexen-3,4-yl-1 ,2-dicarboxylic anhydride or a mixture of two or more thereof.

Examples of alkanolamines are di-or trialkanolamines for example diethanolamine, di-isopropanolamine, 2-amino-2-ethyl-1 ,3-propanediol, tris(hydroxymethyl)aminomethane. According to the preferable example of the invention, the emulsion may be an oil-in-water emulsion or a water-in-oil emulsion.

In case the emulsion is an oil-in-water emulsion, the hyperbranched polyesteramide may be preferably a water-soluble hyperbranched polyesteramide.

The hyperbranched polyesteramide may be preferably a water soluble hyperbranched polyesteramide prepared by polycondensating a di-or trialkanolamine and a cyclic anhydride selected from the group consisting of succinic anhydride, Ci-Ci₈ alkylsuccinic anhydrides, CrCi₈ alkenylsuccinic anhydrides, and a mixture of two or more thereof.

In case the emulsion is a water-in-oil emulsion, the hyperbranched polyesteramide may be preferably an oil soluble hyperbranched polyesteramide.

The hyperbranched polyesteramide may be preferably an oil soluble hyperbranched polyesteramide prepared by polycondensating a di-or trialkanolamine and a cyclic anhydride selected from the group consisting of phthalic anhydride, cyclohexyl-1 , 2-dicarboxylic anhydride, cyclohexen-3,4-yl-1 ,2-dicarboxylic anhydride, polyisobutenylsuccinic anhydride or a mixture of two or more thereof.

Preferable the hyperbranched polyesteramide is added to the mixture of water and oil in a concentration from 1 ppm to 10,000 ppm, more preferably in a concentration from 1 ppm to 1 ,000 ppm, and most preferably in a concentration from 1 to 500 ppm. Hyperbranched polymers are polymers, which contain a large number of branching sites. Contrary to conventional linear polymers which only contain two end groups, hyperbranched polymers possess a large number of end groups, for example on average at least 5 end groups, preferably on average at least δ end groups.

The hyperbranched polyesteramides according to the present invention are described in European Patent Publication Nos. EP1036106 and EP1306401 , and International Patent Publication Nos. WO 00/58388 and WO 00/56804. The production of the hyperbranched polyesteramides according to the present invention can be done by polycondensation of alkanolamines and cyclic anhydrides with optional modification of the end groups, as described in above cited patents

The chemistry of the polyesteramides allows the introduction of a variety of functionalities, which make these polymers useful as demulsifiers. Preferred functional end groups are -OH, -COOH, -NR₁R₂, where R₁ and R₂ can be equal or different alkyl groups from C₁ to C₂₂, -OOC-R or -COOR, where R is an alkyl or aralkyl group. Other possible end groups are derived from polymers, e.g. polyethylene glycol, polypropylene glycol, silicones or fluoropolymers. Still other end groups are derived from cyclic compounds, e.g. morpholine, piperidine or derivatives of piperazine. Especially preferred are -OH, alkyl, and polyethylene glycol end groups. The above cited patent publications describe several methods to produce hyperbranched polyesteramides with these functionalities.

It is possible, and often even desirable, to combine a number of different end group functionalities in a single hyperbranched polyesteramide molecule in order to obtain desirable properties of the polymer i.e., as a demulsifier.

Another possibility to vary the properties of a hyperbranched polyesteramide is by variation of the cyclic anhydride, which is used to build up the polymer structure. Preferred cyclic anhydrides with different functionalities are succinic anhydride, alkylsuccinic anhydrides (where the length of the alkyl chain can vary from C₁ to C₁₈), alkenylsuccinic anhydrides (where the length of the alkenyl chain can vary from C₁ to C₁₈), polyisobutenylsuccinic anhydride, phthalic anhydride, cyclohexyl-1 ,2- dicarboxylic anhydride, cyclohexen-3,4-yl-1 ,2-dicarboxylic anhydride and other cyclic anhydrides. Especially preferred are succinic anhydride and dodecenyl succinic anhydride. It is possible to combine more than one type of anhydride to produce a hyperbranched polyesteramide with the desired properties e.g. as a demulsifier.

The structure and properties of the polyesteramides according to the present invention can be varied over a broad range of e.g. polarities, solubilities and interfacial activities. This makes the hyperbranched polyesteramides applicable to solve a variety of emulsion problems. Oil-in-water emulsions can be broken by appropriate water-soluble hyperbranched polyesteramides, while water-in-oil emulsions can be broken by appropriate oil-soluble hyperbranched polyesteramides. A man skilled in the art can choose the optimal properties and components needed to provide a demulsifier, which gives the best solution to break an emulsion.

The concentration of hyperbranched polyesteramides added to the emulsion mixture may be preferably 1 ppm to 10,000 ppm, more preferably 1 to 1 ,000 ppm, and most preferably 1 to 500 ppm. Another aspect of the present invention is the use of the hyperbranched polyesteramides to prevent emulsion formation. This can be realized by adding the hyperbranched polyesteramide to the water or the oil phase before the water and the oil phase are mixed. In a system which is expected to form an oil-in- water emulsion, a water soluble demulsifier polymer is selected which is to be added to the aqueous phase in order to prevent emulsion formation. In the case of a- water-in-oil emulsion, an oil soluble demulsifier polymer can be added to the oil phase in order to prevent emulsion formation.

In the use of preventing the formation of emulsions, the concentration of hyperbranched polyesteramide may vary from 1 ppm to 10,000 ppm, more preferably from 1 to 1,000 ppm, and most preferably from 1 to 500 ppm.

The process according to the present invention may for example use one or more hyperbranched polyesteramides in combination or may use formulations comprising other active ingredients as necessitated by specific applications. Examples of other ingredients with specific activity are corrosion inhibitors, antifoaming agents, biocides, detergents, rheology modifiers, demulsifiers, flow assurance chemicals and other functions as made necessary by the application. Application of the hyperbranched polyesteramide in the process according to the invention may be as solid or liquid, or dissolved in a solvent which can be chosen by those skilled in the art and as determined by the properties of the specific emulsion. The invention is further illustrated with the following examples.

Preparation of Hyperbranched Polvesteramide 1

A water soluble hyperbranched polyesteramide was synthesized by the polycondensation at 180 °C of 412 grams of diisopropanolamine, 206 grams of dodecenylsuccinic anhydride and 181 grams of succinic anhydride. The number- average molecular weight of the polymer is about 1500. A stock solution of this hyperbranched polyesteramide 1 was prepared by dissolving 1.4 grams of the polymer in 30.1 grams of water.

Preparation of Hyperbranched Polvesteramide 2 An oil soluble hyperbranched polyesteramide was synthesized by the polycondensation at 180 ⁰C of 118 grams of diisopropanolamine, 301 grams of cyclohexane-1 ,2-dicarboxylic anhydride and 436 grams of polyethyleneglycol monomethylether, containing 7 ethylene oxide groups. The number-average molecular weight of the polymer was 6500.

Preparation of Emulsion A

An emulsion is prepared by mixing 8 grams of n-hexane, 2 grams of water and 0.2 grams of ethoxylated laurylalcohol containing 23 ethylene oxide groups. This resulted in a highly viscous and stable hexane-in-water emulsion.

Preparation of Emulsion B

An emulsion is prepared by mixing 20 grams of n-hexane, 20 grams of water and 0.2 grams of ethoxylated laurylalcohol containing 23 ethylene oxide groups as emulsifier. This resulted in a highly viscous and stable hexane-in-water emulsion.

Example 1

The stock solution of Hyperbranched Polyesteramide 1 was further diluted with water to a concentration of 1.82 mg/ml. 25 microliters of this dilute solution were added to 5 ml of Emulsion A (corresponding to about 9 ppm of polymer in the mixture). This resulted in a fast and complete separation of the emulsion into two clear and sharply defined liquid phases.

Example 2

The procedure for preparing Emulsion B was prepared, but 10 microliters of the dilute aqueous solution of Hyperbranched Polyesteramide 1 was added to the water before mixing hexane, water and emulsifier (corresponding to about 1 ppm of polymer in the mixture). When the components were mixed, no emulsion was formed. When the mixing stopped, the components immediately separated into two clear and sharply defined liquid phases.

Example 3

A crude oil of 15 API gravity, containing 57 % by volume emulsified salt water, was treated with a xylene solution of the Hyperbranched Polyesteramide 2, so that the polymer content was 150 ppm. After 5 hours, more than 95 % of the water content had dropped out of the oil.

Claims

1. A process of contacting a hyperbranched polyesteramide, which is a polycondensate of a di- or trialkanolamine and a cyclic anhydride, with a mixture of water and oil.

2. The process according to claim 1 , wherein the mixture comprises an emulsion of water and oil, and the emulsion is broken into water and oil phases when the emulsion contacts with the hyperbranched polyesteramide.

3. The process according to anyone of claims 1-2, wherein the hyperbranched polyesteramide is added to the emulsion of water and oil

4. The process according to anyone of claims 1-2, wherein the hyperbranched polyesteramide is added to the water or the oil phase before the water and the oil phase are mixed.

5. The process according to any one of claims 2-4, wherein the emulsion is an oil-in-water emulsion or a water-in-oil emulsion.

6. The process according to anyone of claims 2-5, wherein the emulsion is an oil- in-water emulsion and the hyperbranched polyesteramide is a water-soluble hyperbranched polyesteramide.

7. The process according to anyone of claims 2-5, wherein the emulsion is a water-in-oil emulsion and the hyperbranched polyesteramide is an oil soluble hyperbranched polyesteramide

8. The process according to any one of the claims 1-7, wherein the cyclic anhydride is selected from the group consisting of succinic anhydride, C₁-Ci₈ alkylsuccinic anhydrides, C₁-C₁₈ alkenylsuccinic anhydrides, polyisobutenylsuccinic anhydride, phthalic anhydride, cyclohexyl-1 ,2- dicarboxylic anhydride, cyclohexen-3,4-yl-1 ,2-dicarboxylic anhydride or a mixture of two or more thereof.

9. The process according to claim 6, wherein the water soluble hyperbranched polyesteramide is prepared by polycondensating a di- or trialkanolamine and a cyclic anhydride selected from the group consisting of succinic anhydride, C₁- C₁₈ alkylsuccinic anhydrides, C₁-C₁₈ alkenylsuccinic anhydrides, or a mixture of two or more thereof.

10. The process according to claim 7, wherein oil soluble hyperbranched polyesteramide is prepared by polycondensating a di- or trialkanolamine and a cyclic anhydride selected from the group consisting of phthalic anhydride, cyclohexyl-1 ,2-dicarboxylic anhydride, cyclohexen-3,4-yl-1 ,2-dicarboxylic anhydride, polyisobutenylsuccinic anhydride or a mixture of two or more thereof.

11. The process according to any one of the claims 1-10, wherein the hyperbranched polyesteramide is added to the mixture in a concentration from 1 ppm to 10,000 ppm.

12. The process according to claim 11 , wherein the hyperbranched polyesteramide is added to the mixture in a concentration from 1 ppm to 1 ,000 ppm.