WO2022042277A1

WO2022042277A1 - Method and extraction agent for methanol to olefins wash water system antifouling

Info

Publication number: WO2022042277A1
Application number: PCT/CN2021/111498
Authority: WO
Inventors: Fei XIA
Original assignee: Ecolab Usa Inc.
Priority date: 2020-08-28
Filing date: 2021-08-09
Publication date: 2022-03-03
Also published as: CN114105323A

Abstract

Methods and compositions are described for removing solids from an aqueous medium in an olefin production process. The methods and compositions may also prevent or reduce fouling in the olefin production process. The method may include adding a composition to the aqueous medium, and the composition may include a cationic polymer and an ammonium salt. The cationic polymer may include acrylamide and a cationic monomer.

Description

METHOD AND EXTRACTION AGENT FOR METHANOL TO OLEFINS WASH WATER SYSTEM ANTIFOULING

BACKGROUND 1. Field of the Invention

The present disclosure generally relates to preventing or reducing fouling in a methanol-to-olefins (MTO) wash water system. More particularly, the disclosure pertains to compositions and methods to prevent or reduce hydrocarbon foulants in the MTO wash water system.

2. Description of the Related Art

The MTO process converts methanol to other commodity products, such as olefins and gasoline. The methanol used in the MTO process can be made from coal-derived synthetic gas ( “syngas” ) or natural gas feedstock. Methanol can be produced from the catalytic conversion of hydrogen and carbon monoxide in coal-derived syngas. MTO processes utilize zeolite catalysts to make the conversion of methanol to olefins economically feasible. The MTO process includes feeding crude methanol into a reactor containing catalyst where the methanol is converted into olefins. The reaction products exit the reactor and are fed into a quench or stripping tower. The gas exiting the quench or stripping tower may then proceed to further processing and purification units, such as a demethanizer, an acetylene saturator, or a dryer to produce pure ethylene, propylene, or other olefins.

Olefin formation from methanol proceeds through a complex network of chemical reactions potentially resulting in the formation of multiple byproducts or unwanted species. The byproducts or unwanted species and catalyst fines exit the reactor in the reaction gas. The reaction gas from the MTO reactor carries the catalyst fines and byproducts, such as poly-methylbenzene, into the quench or stripping tower. The byproducts or unwanted species become entrained in the water, and will cause fouling in the quench water loop and/or the wash water loop, especially in heat exchangers.

The MTO process converts methanol into olefins using a catalytic reactor. The reaction product stream may also contain catalyst fines and reaction byproducts, such as poly-methylbenzene, that become entrained in quench or wash water. The catalyst fines and reaction byproducts entrained in the process water foul downstream process equipment. For example, heat exchanger tubes can become significantly fouled leading to a loss in heat transfer and process efficiency. Fouling causes an increase in the frequency of offline cleaning using high pressure washing, and heat exchanger efficiency often cannot be recovered after mechanical cleaning. Furthermore, fouling can disrupt operation of quench water tower, wash water tower, cyclone hydraulic separators, waste water stripper, and anywhere in the process water loop. Sometimes, the fouling is so severe that the MTO plant must be shut down and cleaned manually.

BRIEF SUMMARY

A method of treating an aqueous medium of an MTO process is disclosed. The method may include adding a composition to MTO process water, wherein the composition may include a cationic polymer and an ammonium salt.

In some aspects, the cationic polymer may be a copolymer of acrylamide and a cationic monomer.

In some aspects, the cationic monomer may be selected from dimethylaminoethylmethacrylate benzyl chloride salt (DMAEM. BCQ) , dimethylaminoethylacrylate benzyl chloride salt (DMAEA. BCQ) , dimethylaminoethylacrylate methyl chloride salt (DMAEA. MCQ) , dimethylaminoethylacrylate methyl chloride salt (DEAEA. MCQ) , dimethylaminoethylmethacrylate methyl chloride salt (DMAEM. MCQ) , dimethylaminoethylmethacrylate methyl sulfate salt (DMAEM. MSQ) , dimethylaminoethylacrylate methyl sulfate salt (DMAEA. MSQ) , methacrylamidopropyltrimethylammonium chloride (MAPTAC) , acrylamidopropyltrimethylammonium chloride (APTAC) , and any combination thereof.

In some aspects, the cationic monomer may be DMAEA. MCQ.

In some aspects, the cationic polymer is a terpolymer of acrylamide, DMAEA. MCQ, and DMAEA. BCQ.

In some aspects, the ammonium salt is ammonium sulfate.

In some aspects, the cationic polymer is a terpolymer of acrylamide, DMAEA. MCQ, and DMAEA. BCQ and the ammonium salt is ammonium sulfate.

In some aspects, the cationic polymer is linear or structured.

In some aspects, the method further includes removing polymethyl-benzene from the MTO process water.

In some aspects, the composition further includes a cationic coagulant, the cationic coagulant being aluminum chlorohydrate.

In some aspects, the composition may be added to the MTO process water in an amount ranging from about 1 ppm to about 1000 ppm.

In some aspects, the composition may be added to the MTO process water in an amount ranging from about 1 ppm to about 200 ppm.

In some aspects, the composition may be added to the MTO process water in an amount ranging from about 10 ppm to about 500 ppm.

In some aspects, the composition is added to the MTO process water in an amount of about 30 ppm.

In some aspects, the composition may further include a solvent. In some aspects, the solvent may be water, an alcohol, or any combination thereof.

In some aspects, the method may include removing solids from the MTO process water. In some aspects, the solids may comprise polymethylbenzene.

In some embodiments, the method may further include further comprising feeding the MTO process water treated with the composition into a cyclone hydraulic separator or separator tank.

In some embodiments, a use of a composition for treating an aqueous medium of a MTO process is disclosed. The composition may include a settling aid selected from a cationic polymer and an ammonium salt.

The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter that form the subject of the claims of this application. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other embodiments for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent embodiments do not depart from the spirit and scope of the disclosure as set forth in the appended claims.

DETAILED DESCRIPTION

Various embodiments are described below. The relationship and functioning of the various elements of the embodiments may better be understood by reference to the following detailed description. However, embodiments are not limited to those illustrated below. In certain instances, details may have been omitted that are not necessary for an understanding of embodiments disclosed herein.

The present disclosure describes methods and compositions for removing solids from an aqueous medium in an olefin production process. The methods and compositions may also prevent or reduce fouling in the olefin production process.

A method is disclosed for treating an aqueous medium of an MTO process. The method may include adding a composition to MTO process water, wherein the composition may include a cationic polymer and an ammonium salt.

As used herein “MTO process” refers to a process that converts methanol to other commodity products, such as olefins and gasoline. The methanol used in the MTO process can be derived from coal-derived synthetic gas or natural gas feedstock. Methanol can be produced from the catalytic conversion of hydrogen and carbon monoxide in coal-derived syngas. MTO processes utilize zeolite catalysts to make the conversion of methanol to olefins economically feasible. The MTO process includes feeding crude methanol into a reactor containing catalyst where the methanol is converted into olefins. The reaction products exit the reactor and are fed into a quench or stripping tower. The gas exiting the quench or stripping tower may then proceed to further processing and purification units, such as a demethanizer, an acetylene saturator, or a dryer to produce pure ethylene, propylene, or other olefins.

An aqueous medium is generally used in the quench or stripping tower to remove impurities from the desired olefins stream. In some aspects, the aqueous medium is MTO process water. As used herein “MTO process water” refers to water that has contacted or will contact the reaction product stream from the MTO reactor. The MTO process water may contact the reaction product stream in the quench or stripping tower, for example.

The cationic polymer may be a homopolymer of a cationic monomer or a copolymer of two or more monomers. In some aspects, the cationic polymer is a terpolymer comprising three chemically distinct monomer units.

As used herein “copolymer” refers to a polymer containing at least two polymerizable monomers. Copolymers may include random copolymers, block copolymers, or graft copolymers. Copolymers may include, but are not limited to, linear, branched, hyperbranched, star, and dendritic structures.

In some aspects, the cationic polymer may be a linear polymer. In other aspects, the cationic polymer may be a branched polymer. As used herein “branched polymers” refers to polymers where at least one substituent on the polymer chain, for example hydrogen, is replaced by a covalently bonded polymer.

In some aspects, the cationic polymer may be a network polymer. As used herein “network polymer” refers to cross-linked linear or branched polymers. The cross-links between polymers may be covalent.

As used herein “monomer” refers to any polymerizable molecule, for example polymerization may proceed via radical initiation and propagation or by condensation reactions.

In some aspects, the cationic polymer includes acrylamide or methacrylamide monomer and a cationic monomer.

In some embodiments, the cationic monomer may be any positively charged acrylate or methacrylate monomer. Examples of cationic monomers include, but are not limited to, dimethylaminoethylmethacrylate benzyl chloride salt (DMAEM. BCQ) , dimethylaminoethylacrylate benzyl chloride salt (DMAEA. BCQ) , dimethylaminoethylacrylate methyl chloride salt (DMAEA. MCQ) , dimethylaminoethylacrylate methyl chloride salt (DEAEA. MCQ) , dimethylaminoethylmethacrylate methyl chloride salt (DMAEM. MCQ) , dimethylaminoethylmethacrylate methyl sulfate salt (DMAEM. MSQ) , dimethylaminoethylacrylate methyl sulfate salt (DMAEA. MSQ) , methacrylamidopropyltrimethylammonium chloride (MAPTAC) , or acrylamidopropyltrimethylammonium chloride (APTAC) . In some aspects, the cationic monomer may be DMAEA. MCQ. In some aspects, the cationic monomer may be DMAEA. BCQ.

The cationic polymer may include a single cationic monomer or a mixture of different cationic monomers. In some aspects, the cationic polymer is a copolymer of acrylamide and DMAEA. MCQ. In some aspects, the cationic polymer is a copolymer of acrylamide and DMAEA. BCQ. In some aspects, the cationic polymer is a terpolymer of acrylamide, DMAEA. MCQ, and DMAEA. BCQ.

The RSV of the cationic polymer may be about 1 dL/g to about 40 dL/g. In some aspects, the RSV may range from about 3 dL/g to about 26 dL/g, about 3 dL/g to about 10 dL/g, about 10 dL/g to about 15 dL/g, about 16 dL/g to about 26 dL/g. RSV can be determined using a viscometer. The RSV can be determined at a temperature of about 25 ℃ and at a concentration of about 25 wt%, about 5 wt%to 15 wt%, about 15 wt%to about 25 wt%, or about 35 wt%to about 45 wt%.

In some aspects, the cationic polymer may include acrylamide or methacrylamide in an amount ranging from about 5 mol%to about 85 mol% relative to any other co-monomer in the cationic polymer. In some aspects, the amount of acrylamide in the cationic monomer may be about 35 mol%, about 40 mol%, about 45 mol%, about 50 mol%, about 55 mol%, about 60 mol%, or about 65 mol%.

In some aspects, the amount of cationic monomer in the cationic polymer may range from about 10 mol%to about 90 mol%. In some embodiments, the amount of cationic monomer in the cationic polymer may range from about 20 mol%to about 90 mol%, about 50 mol%to about 90 mol%, about 60 mol%to about 90 mol%, or about 70 mol%to about 90 mol%. The mol%refers to the relative amount of monomer in the cationic polymer relative to other polymers. The mol%of cationic monomer in a cationic polymer can also be characterized as the charge of the polymer.

In other aspects, the composition may consist of a cationic polymer, an ammonium salt, and a solvent. In some aspects, the composition may include a cationic coagulant. In some aspects, the composition may include a cationic polymer. In some aspects, the composition may consist of a cationic polymer. In some aspects, the composition may consist essentially of a cationic polymer and an ammonium salt.

In some aspects, the cationic polymer may be added to the aqueous medium in an amount ranging from about 1 ppm to about 1000 ppm. In some aspects, the cationic polymer may be added to the aqueous medium in an amount ranging from about 1 ppm to about 200 ppm, about 1 ppm to about 50 ppm, about 10 ppm to about 50 ppm, about 5 ppm to about 20 ppm, about 30 ppm to about 50 ppm, about 10 ppm to about 20 ppm, or about 35 ppm to about 45 ppm. In some aspects, the amount of cationic polymer added to the aqueous medium may be about 15 ppm, about 20 ppm, about 30 ppm, or about 40 ppm.

The ammonium salt in the composition is not particularly limited. Examples of suitable ammonium salts include, but are not limited to, ammonium sulfate, ammonium carbonate, ammonium chloride, and ammonium nitrate. In some aspects, the ammonium salt is ammonium sulfate.

In some aspects, the ammonium salt may be added to the aqueous medium in an amount ranging from about 1 ppm to about 1000 ppm. In some aspects, the ammonium salt may be added to the aqueous medium in an amount ranging from about 1 ppm to about 200 ppm, about 1 ppm to about 50 ppm, about 10 ppm to about 50 ppm, about 5 ppm to about 20 ppm, about 30 ppm to about 50 ppm, about 10 ppm to about 20 ppm, or about 35 ppm to about 45 ppm. In some aspects, the amount of ammonium salt added to the aqueous medium may be about 15 ppm, about 20 ppm, about 30 ppm, or about 40 ppm.

In some aspects, the composition may further include a cationic coagulant such as an aluminum compound. Examples of aluminum compounds include, but are not limited to, aluminum chlorohydrate. The cationic coagulant may be added to the aqueous medium in an amount ranging from about 10 ppm to about 1000 ppm. In some aspects, the cationic coagulant may be added to the aqueous medium in an amount ranging from about 10 ppm to about 500 ppm, about 50 to about 500 ppm, about 100 ppm to about 500 ppm, about 100 ppm to about 400 ppm, about 100 ppm to about 300 ppm, or about 100 ppm to about 250 ppm. In some aspects, the amount of cationic coagulant added to the aqueous medium may be about 200 ppm, about 180 ppm, or about 150 ppm.

In some aspects, the composition may further include a solvent. Examples of solvents include, but are not limited to, water, alcohol, or any combination thereof.

In some aspects, the method may include removing solids from the aqueous medium. The solids may include catalyst fines or other organic material. In some embodiments, the solids may include aluminosilicophosphate.

The method may include reducing the chemical oxygen demand (COD) of the MTO process water as a result of treating the water with the composition. In some aspects, the COD may be reduced by about 50%. In some aspects, the COD may be reduced by about 20%to about 50%.

In some aspects, the method may include removing solids from the aqueous medium using a cyclone hydraulic separator or separator tank. The aqueous medium may first be treated with the composition and then the aqueous medium would be fed to the cyclone hydraulic separator or separator tank. Cyclone hydraulic separators may be downstream of the quench water tower, and may be used to remove solids that have aggregated as a result of the composition. Some solids in the aqueous medium have a particle size that is too small to be removed by cyclone hydraulic separators or separation tank. Without being bound by theory, the compositions disclosed herein cause aggregation of suspended solids in the aqueous medium. The compositions may cause an increase in particle size from an un-removable size to a size that can be removed using cyclone hydraulic separators or separation tank. If the catalyst fines are not removed, fouling can occur in the quench water loop and/or wash water loop, especially in heat exchangers.

An MTO process may include olefin recovery units and several purifying units, such as, but not limited to, a quench tower, a wash water tower, an alkaline washing tower, a drying tower, and high pressure depropane tower. The MTO process may be a dimethyl ether/methanol to olefins (DMTO) process.

The compositions disclosed herein may be added to any process unit in the MTO process that contacts an aqueous medium. In some aspects, the composition may be added to a quench tower, a wash water tower, an alkaline washing tower, and/or a heat exchanger. The compositions may be added to the aqueous medium after passing through a quench tower and before entering a cyclone hydraulic separator.

Process units used in the process may include, but are not limited to, a quench water tower, a wash water tower, cyclone hydraulic separators, and a waste water stripper. The method may include adding a composition to the process unit to remove suspended solids. The process unit may be a heat exchanger, for example. The composition may be any composition described in the present application. In some aspects, the process unit may include an aqueous medium.

In some aspects, the aqueous medium may be process water, such as, but not limited to, quench water, wash water, and other water in the process water loop.

In some embodiments, the method may further include dispersing the foulant, wherein the foulant may comprise organic matter and/or inorganic matter. The inorganic matter portion of the foulant may comprise, for example, aluminosilicophosphate. The organic portion of the foulant may comprise, for example, polymethylbenzene. In some embodiments, the foulant may comprise aluminosilicophosphate and polymethylbenzene.

The composition may be added to an aqueous medium that enters the process unit. The manner in which the composition is added to the aqueous medium is not critical. The cationic polymer and the ammonium salt can be added to the aqueous medium in any order or simultaneously, for example, the cationic polymer may be mixed with the ammonium salt prior to adding them to the aqueous medium or the cationic polymer may be added before or after adding the ammonium salt to the aqueous medium.

The compositions can optionally include one or more additives. Suitable additives include, but are not limited to, corrosion inhibitors, scale inhibitors, water clarifiers, dispersants, emulsion breakers, pH modifiers, surfactants, solvents, and combinations thereof.

Suitable corrosion inhibitors include, but are not limited to, amidoamines, quaternary amines, amides, phosphate esters, and combinations thereof.

Suitable scale inhibitors include, but are not limited to, phosphates, phosphate esters, phosphoric acids, phosphonates, phosphonic acids, polyacrylamides, salts of acrylamido-methyl propane sulfonate/acrylic acid copolymer (AMPS/AA) , phosphinated maleic copolymer (PHOS/MA) , salts of a polymaleic acid/acrylic acid/acrylamido-methyl propane sulfonate terpolymer (PMA/AMPS) , and combinations thereof.

Suitable water clarifiers include, but are not limited to, inorganic metal salts such as alum, aluminum chloride, aluminum chlorohydrate, iron sulfate, iron chloride, and polyferric sulfate or organic polymers such as acrylic acid based polymers, acrylamide based polymers, polymerized amines, alkanolamines, thiocarbamates, cationic polymers such as diallyldimethylammonium chloride (DADMAC) , and combinations thereof.

Suitable pH modifiers include, but are not limited to, alkali hydroxides, alkali carbonates, alkali bicarbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, alkaline earth metal bicarbonates and mixtures or combinations thereof. Exemplary pH modifiers include NaOH, KOH, Ca (OH) ₂, CaO, Na ₂CO ₃, KHCO ₃, K ₂CO ₃, NaHCO ₃, MgO, and Mg (OH) ₂.

Suitable surfactants include, but are not limited to, anionic surfactants, cationic surfactants, nonionic surfactants, and combinations thereof. Anionic surfactants include alkyl aryl sulfonates, olefin sulfonates, paraffin sulfonates, alcohol sulfates, alcohol ether sulfates, alkyl carboxylates and alkyl ether carboxylates, and alkyl and ethoxylated alkyl phosphate esters, and mono and dialkyl sulfosuccinates and sulfosuccinamates, and combinations thereof. Cationic surfactants include alkyl trimethyl quaternary ammonium salts, alkyl dimethyl benzyl quaternary ammonium salts, dialkyl dimethyl quaternary ammonium salts, imidazolinium salts, and combinations thereof. Nonionic surfactants include alcohol alkoxylates, alkylphenol alkoxylates, block copolymers of ethylene, propylene and butylene oxides, alkyl dimethyl amine oxides, alkyl-bis (2-hydroxyethyl) amine oxides, alkyl amidopropyl dimethyl amine oxides, alkylamidopropyl-bis (2-hydroxyethyl) amine oxides, alkyl polyglucosides, polyalkoxylated glycerides, sorbitan esters and polyalkoxylated sorbitan esters, and alkoyl polyethylene glycol esters and diesters, and combinations thereof. Also included are betaines and sultanes, amphoteric surfactants such as alkyl amphoacetates and amphodiacetates, alkyl amphopropripionates and amphodipropionates, alkyliminodiproprionate, and combinations thereof.

In the aspects where the surfactants are added separately, each surfactant may be added at the same location or at a different location in the process. The surfactants may be added simultaneously at the same or different locations, or at different times in the same or different locations.

In some aspects, the composition may not include an ethoxylated alcohol, a 2-nitro-4-alkylphenol polyethoxy ether, or alkylphenol polyethoxy ether sodium sulfate.

EXAMPLES

Example 1

Samples of quench water were obtained from a water used in an MTO process. The quench water contained polymethylbenzene (PMB) and organic material.

In the lab evaluations, a turbidity measurement was used for candidate screening. The turbidity test showed that the compositions disclosed herein can remove suspended oil drop and/or solids effectively. However, the turbidity method cannot fully prove whether those chemicals can remove the hydrocarbon fouling substances in the wash water or not. Hence, a COD test was further applied to show if the disclosed compositions can remove hydrocarbon targets in the wash water.

Table 1 shows the additives tested for their ability to lower the COD of the water which is related to the amount of PMB removed from the water. The RSV for each polymer was calculated according to the following formula RSV = [ (η /η ₀ ) ] /c, where η is the viscosity of the polymer solution, η ₀ is the viscosity of the solvent, and c is the concentration of the polymer solution. The RSV for the polymers in Table 1 was determined at a temperature of about 25 ℃. The RSV for Additive 1 was calculated at a concentration of about 15 to about 25 wt%, Additive 2 was calculated at about 5 to about 15 wt%, and Additive 3 was calculated at a concentration of about 35 to about 45 wt%.

Table 1. Additives and their active ingredients

About 40 grams of wash water sample was added to a flask and heated to a temperature of about 90 ℃. The turbidity (T ₀) was then measured along with the COD (C ₀) . The additives were added to and mixed with the wash water and the turbitity and COD were again measured to determine a T ₁ and C ₁. The removal rate of solids (for example catalyst fines) was calculated by comparing the turbidity of the quench water with and without additive (COD Removal rate%= (C ₀-C ₁) /C ₀*100%.

Table 2 shows the change in COD for Additives listed in Table 1. The lab results indicate that Additive 1 and Additive 2 reduce turbidity. It can be seen that Additive 1 can reduce turbidity at a lower dosage compared to the other Additives. The COD was measured for water treated with Additive 1, Additive 3, and a mixture of Additive 4 and 3.

The result shows that Additive 3 and Additive 1 can reduce both the turbidity and the COD. It means they can both remove the suspended solids such as soluble organic material.

Table 2. Solid removal rates for various additives

Any composition disclosed herein may comprise, consist of, or consist essentially of any of the compounds /components disclosed herein. In accordance with the present disclosure, the phrases “consist essentially of, ” “consists essentially of, ” “consisting essentially of, ” and the like limit the scope of a claim to the specified materials or steps and those materials or steps that do not materially affect the basic and novel characteristic (s) of the claimed invention.

As used herein, the term "about" refers to the cited value being within the errors arising from the standard deviation found in their respective testing measurements, and if those errors cannot be determined, then "about" refers to within 10%of the cited value.

All of the compositions and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While this invention may be embodied in many different forms, there are described in detail herein specific preferred embodiments of the invention. The present disclosure is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. In addition, unless expressly stated to the contrary, use of the term “a” is intended to include “at least one” or “one or more. ” For example, “a polymer” is intended to include “at least one polymer” or “one or more polymers. ”

Any ranges given either in absolute terms or in approximate terms are intended to encompass both, and any definitions used herein are intended to be clarifying and not limiting. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges (including all fractional and whole values) subsumed therein.

Furthermore, the invention encompasses any and all possible combinations of some or all of the various embodiments described herein. It should also be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims

A method of treating an aqueous medium of a methanol to olefins (MTO) process, comprising:

adding a composition to MTO process water, wherein the composition comprises a cationic polymer and an ammonium salt.
The method of claim 1, wherein the cationic polymer is a copolymer of acrylamide and a cationic monomer.
The method of claim 2, wherein the cationic monomer is selected from

dimethylaminoethylmethacrylate benzyl chloride salt (DMAEM. BCQ) ,

dimethylaminoethylacrylate benzyl chloride salt (DMAEA. BCQ) ,

dimethylaminoethylacrylate methyl chloride salt (DMAEA. MCQ) ,

dimethylaminoethylacrylate methyl chloride salt (DEAEA. MCQ) ,

dimethylaminoethylmethacrylate methyl chloride salt (DMAEM. MCQ) ,

dimethylaminoethylmethacrylate methyl sulfate salt (DMAEM. MSQ) ,

dimethylaminoethylacrylate methyl sulfate salt (DMAEA. MSQ) ,

methacrylamidopropyltrimethylammonium chloride (MAPTAC) ,

acrylamidopropyltrimethylammonium chloride (APTAC) , and any combination thereof.
The method of any one of claims 2-3, wherein the cationic monomer is DMAEA. MCQ.
The method of any one of claims 1-3, wherein the cationic polymer is a terpolymer of acrylamide, DMAEA. MCQ, and DMAEA. BCQ.
The method of any one of claims 1-5, wherein the ammonium salt is ammonium sulfate.
The method of any one of claims 1-3, wherein the cationic polymer is a terpolymer of acrylamide, DMAEA. MCQ, and DMAEA. BCQ and the ammonium salt is ammonium sulfate.
The method of any one of claims 1-7, wherein the cationic polymer is linear or structured.
The method of any one of claims 1-8, further comprising removing polymethylbenzene from the MTO process water.
The method of any one of claims 1-9, wherein the composition further comprises a cationic coagulant, the cationic coagulant being aluminum chlorohydrate.
The method of any one of claims 1-10, wherein the composition is added to the MTO process water in an amount ranging from about 1 ppm to about 1000 ppm.
The method of any one of claims 1-11, wherein the composition is added to the MTO process water in an amount ranging from about 1 ppm to about 200 ppm.
The method of any one of claims 1-12, wherein the composition is added to the MTO process water in an amount of about 30 ppm.
The method of any one of claims 1-12, wherein the composition is added to the MTO process water in an amount ranging from about 10 ppm to about 500 ppm.
The method of any one of claims 1-14, wherein the composition further comprises a solvent.
The method of claim 15, wherein the solvent is water, an alcohol, or any combination thereof.
The method of any one of claims 1-16, further comprising removing solids from the MTO process water.
The method of any one of claims 1-17, further comprising feeding the MTO process water treated with the composition into a cyclone hydraulic separator or separator tank.
The method of any one of claims 17-18, wherein the solids comprise polymethylbenzene.
The method of any one of claims 1-19, wherein the cationic polymer has an RSV ranging from about 1 dL/g to about 30 dL/g.