1. 1
Industrial preparation of Demulsifiers
Chandran Udumbasseri, Technical consultant
cudumbasseri@yahoo.co.in.
Theory and applications
Demulsifier is a chemical used to break emulsions and separate into two phases.
Water is separated from crude oil by dozing demulsifier and breaking the
emulsion.
The emulsion of water in crude oil is thermodynamically unstable but kinetically
very stable. Natural surfactants, wax and solids (inorganic salts, zinc, iron,
aluminum sulfate, calcium carbonate, silica and iron sulfide) stabilize such
emulsions.
Asphaltene compounds were found to be one of the contributing materials to the
stability of crude oil. Asphaltenes are condensed aromatic rings containing
saturated carbon chains and naphthenic rings as substituents along with hetero
atoms and metals. Asphaltenes are capable of cross linking at the water drop oil
interface and preventing water droplets from coalescence. They are surface
active agents present in the oil water interface.
Emulsifiers:
When two liquids are Immiscible then mixing and making visibly homogenous
pseudo phase formation is difficult. If water and vegetable oil are mixed after
sometime it can be seen that oil floats on the water surface. If mixed and
allowed to stand, the oil droplets entrapped in the water body slowly moves
upwards and join to form floating oil layer. The substance used to stop the
separation into two layers is called emulsifiers
An emulsifier molecule has two ends: one side water loving (hydrophilic end)
and the other end water hating (hydrophobic), the water loving part bonds with
water using hydrogen bonds while water hating part bonds with oil molecule
using Vander Waals forces.
Emulsifier molecules
The hydrophilic 'head' dissolves in the water and the hydrophobic 'tail' dissolves
in the oil. The water and oil droplets become unable to separate out and the
mixture formed is called an emulsion. There are two types of emulsion, water in
oil emulsion and oil in water emulsion.
Demulsifiers
Demulsifiers are surfactants similar to emulsifiers but functions in the reverse
direction, they break the emulsion formed by emulsifiers. As explained above an
emulsifier that formed oil in water can function in the reverse direction. Such

2. 2
emulsifiers can break the emulsion of water in oil type. If the surfactants can
make oil in water emulsion, maybe they can remove water from water in oil
emulsions. So any emulsifier with definite structural properties can be
considered as emulsification and demulsification agent.
Demulsifiers reduce surface tension at the water-oil interface. Demulsifiers are
polymers that act as surfactants. The polymers have both hydrophilic and
hydrophobic groups. The polymeric surfactant, when added to the crude
emulsion locates itself in the interface between water and oil molecules. The
hydrophilic groups orient themselves towards water while the hydrophobic ones
orient themselves towards the oil. At the interface the demulsifier either replaces
the emulsifying surfactant or it provides additional steric forces within the film
interface. In either case, this absorption causes a random film thickness
fluctuation. This random film thickness fluctuation results in an increase in the
film surface area and also results in a localized decrease in the absorbed
stabilizing emulsifier. Hence causing a local increase in interfacial surface tension
and thinning of the film.
The following process takes place during the absorption of the demulsifier at the
interface:
1. The demulsifier absorbs the stabilizing emulsifier at the water liquid interface
and decreases the film forming capability of the emulsifying additives.
2. The demulsifier may render the additives soluble in the water phase and
hence less surface active.
3. The demulsifier may mix with the emulsifying additive and reduce the
interfacial tension at the water oil interface, there by creating less stable water
dispersion.
The demulsifiers used for water separation from crude oil are a combination of
compounds having demulsifying activity and compounds that assist
demulsification but without demulsifying activity.
1. Compounds with demulsifying activity.
1.1. Polyethylene imine alkoxylate.
1.2. Mono or oligo-amine alkoxylate.
1.3. Alkoxylated alkylphenol formaldehyde resin.
1.4. Alkoxylated amine modified alkyl phenol formaldehyde resin.
1.5. Co or ter polymers of alkoxylated acrylates or methacrylates with
vinyl compounds.
1.6. Condesates of mono- or oligo- amine alkoxylates, dicarboxylic acids
and alkylene oxide block polymers (may be quaternized at nitrogen).
1.7. Cros linked products of 1 to 6.
2. Compounds acting as demulsifying assistant.
2.1. Poly alkylene glycol ethers
2.1.1. General Formula, [R’(OA1
)a ..OH]n , R’ = C7 to C20 alkyl group, phenyl
group, alkyl phenyl group: A1
,A2
,A3
= 1,2 alkylene group with 2 to 4
carbon atoms, phenyl ethyl group ( there should be one 1,2 alkylene
group with 4 carbon atoms); a = 1 to 50; n = 1 to 10.
2.1.2. General Formula H-(OA1
)b-(OA2
) c-(OA3
) d-OH (where b, c and d each
has value from 0 to 50 and b+c+d is >3).

3. 3
Demulsifier functioning
The demulsifier tend to act on the emulsion by:
 Flocculation of oil droplets.
 Dropping of water.
 Coalescence of the water droplets.
 The speed and efficiency at which this occurs can be improved by process
equipment design and operating condition (e.g.: Increasing the
temperature, separator design, etc.).
The components of the demulsifier formulation are characterized according to
their primary function. But components can provide multipurpose function in a
particular crude oil. Also inclusion of surface wetters can assist in the treating of
emulsion problem.
Function of different demulsifiers
Oxyalkylated Phenolic Resins
High molecular weight phenolic resin oxyalkylates have been found to be highly
effective as crude oil emulsion breakers. Resins are used on emulsions of the
water-in-oil type and work by counteracting the stabilizing influence of naturally
present emulsifying agents.
They are classified as nonionic surface-active organic chemicals that will not
interact with ionic type chemicals.
Applications
phenolic resin oxyalkylates are generally used in dilute form in aromatic solvent
or blended with chemicals of different generic structures to give synergistic
formulas which may have greater efficiency.
Polyalkylene Glycols
Polyalkylene glycols are non-ionic in character. Polyols work by counteracting
naturally occurring emulsifiers. Polyols have been found to be particularly
effective when used in low salt water brine or in fresh water emulsions. In these
cases, polyols are often formulated with sulfonates or used as is.
Polyols are stable to hydrolysis. Polyols exhibit exceptional ability to lower
interfacial tension and, as a result, have a high degree of wetting activity. For
this reason, polyols can effectively disperse or deflocculate solids.
Applications
Polyalkylene glycols can be used with effectiveness in synergistic blends with
oxyalkylated phenolic resins or with sulfonic acid salts, or in blends of all three,
to break crude oil emulsions of the water in oil type.
Polymeric Elastomers
Polymeric elastomers are used in a variety of geographical locations in standard
emulsion breakers. Rapid penetration through the oil phase to finely emulsified
water droplets has made them indispensable in many areas. This penetration is
vividly demonstrated by the rapid blackening of cream colored emulsions and
the quick brightening of water-hazed emulsions. Being extremely oil soluble in
nature, polymeric elastomers exhibit great tenacity for finishing the dehydration
of crudes where more water-soluble compounds can “wash out” with the water
phase of a partially resolved emulsion.

4. 4
Applications
Polymeric elastomers may require blending with other emulsion breaker
intermediates to achieve complete treatment of water-in-oil emulsion. Polymeric
elastomers can be formulated in toluene, xylene, or heavy aromatic solvent, and
are compatible with other emulsion breaker intermediates. If necessary, alcohols
can be used as brightening or stabilizing agents in these field strength blends.
Polymerized Polyols
Polymerized polyol intermediates are used in a variety of geographical locations
in standard emulsion breakers. Rapid penetration through the oil phase to finely
emulsified water droplets has made them indispensable in many areas. This
penetration is vividly demonstrated by the rapid blackening of cream-colored
emulsions and the quick brightening of water-hazed emulsions.
They are extremely oil soluble in nature and exhibit great tenacity for finishing
the dehydration of crudes where more water-soluble compounds can “wash out”
with the water phase of a partially resolved emulsion.
Applications
Polymerized polyols typically require blending with other emulsion breaker
intermediates to achieve complete treatment of water-in-oil emulsion.
Polymerized polyols can be formulated in toluene, xylene, or heavy aromatic
solvent, and are compatible with other emulsion breaker intermediates. If
necessary, alcohols can be used as brightening or stabilizing agents in these field
strength blends.
Polyol Esters
Polyol esters are a reaction product of a polyalkylene oxide block polymer and a
polyfunctional organic acid. Polyol esters are particularly effective on fresh-water
emulsions and tend not to cause emulsion inversion or oil-in-water emulsions.
Polyol esters act, as do most emulsion breakers, by counteracting the effect of
naturally occurring emulsifiers.
Applications
Polyol esters are an effective emulsion breaker when used separately or in
blends with oxyalkylated phenolic resins. This high molecular weight chemical is
non-ionic in character.
Resin Esters
Resin ester intermediates are reaction products of an oxyalkylated phenolic resin
and an organic carboxylic acid. Resin esters are unusually effective when used
as a detergent or as a wetting agent in emulsion breaker formulations.
Applications
Despite resin ester’s high detergency, they do not cause inversion to oil-in-water
emulsion. Resin esters have also been used in limited applications as a desalting
chemical and in treating slop oils.
Sulfonates
Sulfonates have outstanding characteristics that include low cost and a
resistance to “burning” or “overtreating” when used in formulations to treat

5. 5
crude oil emulsions of the water-in oil type. Sulfonates aid in emulsion breaking
by counteracting naturally occurring emulsifiers and are extremely effective in
resolving loose water emulsions stabilized by solids. Sulfonates are often used in
treating refinery “slop” emulsions as well as tank bottoms.
Applications
Sulfonate intermediates are generally used in conjunction with oxyalkylated
phenolic resins and with polyglycols. The solubility characteristics of sulfonates
enable them to work at the oil/water interface where they are extremely
effective in resolving loose water emulsion stabilized by solids.
Classification
Water droppers
Water droppers coalesce water droplets in the crude oil and release free water.
Predominant type is based on alkyl phenol formaldehyde resins with low levels of
addition of ethylene oxide or propylene oxide. These demulsifiers also show
excellent desalting properties.
Treaters
The primary function of these compounds is to flocculate the large number of
sub-micron water droplets dispersed in the crude oil. Water droplets are thus
concentrated at the base of the oil column prior to coalescence and the crude is
dehydrated above the settling level of the flocs. This can be noticed by the
brightening of the top oil in contrast to its dull appearance when the water
dispersion existed.
The predominant type is based on high molecular poly propylene glycol
molecules with hydrophilic ‘tips’ which solvate into the water droplets and
facilitate gathering.
Hybrids
These compounds incorporate a balance of molecular design features such that
both ‘dropping’ and ‘treating’ characteristics are exhibited. Hybrids are more cost
effective than blends of droppers and treaters.
Desalters
The emulsions coming along the crude to the desalting stage have low amounts
of water and are less stable. Some of the naturally occurring emulsion stabilizers
have been removed at the 1st
stage demulsification process. The droplet size is
not very small. High potential electric field applied coalesce these polar salt
water droplets. A good desalter demulsifier would achieve rapid water separation
at low level addition rates.
Preparation of demulsifier bases
The methods of preparation of demulsifiers are taken from various U.S. Patents
that were developed in their laboratories.
Initially the intermediate product, resin (alkyl phenol formaldehyde resin,
Polyalkylene poly imine resin, Polyalkylene resin, intermediate amine,
polyoxyalkylene glycol, polyoxyalkylene glycol-diglycidyl ether condensate,
polyamidoamine, vinyl polymers) is prepared. This product is then condensed

6. 6
with ethylene oxide, propylene oxide or butylenes oxide or their mixture to make
oxyalkylate. As the number of molecules of ethylene oxide increases the
solubility of the resin in water increases. By increasing other oxides of propylene
and butylenes the solubility of the resin in water is reduced. Depending on the
requirement of degree of solubility in oil/water the ratio of resin to alkylene
oxide is varied.
Most important process in demulsifier preparation is alkoxylation – ethoxylation
and propoxylation.
Alkoxylation by loop reactor
The alkoxylates are produced by batch reaction in SS reactors. The reaction is
carried out at 130-180o
C and the catalyst used was sodium hydroxide (0.1-1%)
solution.
The water is removed by vacuum or by nitrogen stripping. The following reaction is
taking place during this drying step. Water used for solution making and water of
reaction are stripped to make the raw material mix dry.
RXH + M+
OH-
RX-
+ M+
+ H2O

7. 7
Raw material work up
The raw material work up has the following steps
a. Charging the raw material to reactor
b. Vacuum /nitrogen stripping of air and moisture
c. Heating the mixture
d. Charging the catalyst solution
e. Removing water (dilution water and water of reaction) by vacuum stripping
f. Taking a sample and checking moisture content by KF method
g. Heating the mixture to reaction temperature
h. Transferring the heated raw material mixture to loop reactor
1. The raw material is fed to the work up vessel in 15 minutes. The raw material
is subjected to vacuum to remove air and oxygen
2. The catalyst solution (NaOH solution) is then added
3. The raw material mixture is then heated to 90-105o
C by pre-heater
4. All the water (dilution water and water of reaction) is removed by rotary screw
vacuum pump (< 5 torr) (= 1mm Hg). The force in the jet mixer flashes out the
gas ad removed by vacuum. Light components in the raw material are also
removed (2 – 50kg) by this stripping
5. After vacuum drying a sample is drown and checked for moisture content by
KF method
6. If the moisture is within the spec limit, then the catalyzed raw material is
heated to 160-170o
C
7. The heated material is transferred to loop reactor
Reaction
Initiation of polymerization
RX¯ + CH2CH2O RXCH2CH2O-
Polymerization
RXCH2CH2O-
+ CH2CH2O RX(CH2CH2O)CH2CH2O-
+nCH2CH2O
nCH2CH2ORX (CH2CH2O) CH2CH2O-

8. 8
Reaction steps
a. Charging the dry raw materials to the loop reactor
b. Adjust the pressure and temperature of reaction, heat exchanger adjustment
c. Conducting reaction by feeding alkylene oxides
d. Post reaction
e. Transferring to the final treatment vessel (neutralization)
1. The dry raw material mixture is transferred to the loop reactor. The pumping
pressure should be above the existing nitrogen pressure.
2. When all the raw material is charged to, then start loop reactor pump
3. The loop reactor consists of reactor, external loop pump, external heat
exchanger and jet mixer
4. The catalyzed raw material is pumped through an external heat exchanger to
the jet mixer at the top head. The nozzle acts as educator
5. When the catalyzed material passes through the draft tube, impact zone and
diffuser of the jet mixer intimate gas liquid contact takes place
6. The reaction takes place in the impact zone
7. The remaining gas/liquid reaction takes place in the bubble column reaction
zone. At the exit of the jet mixer the un-reacted gas and nitrogen pass into the
head space of the loop reactor. From there the gas is re-circulated by the
suction from the jet mixer

9. 9
8. Once the nitrogen pressure is set around 30-45psi and reaction temperature
is set between 160-170o
C (120o
C), the alkylene oxide is introduced in to the
suction chamber of jet mixer
9. The temperature setting 160-170o
C is for ethoxylates, 120o
C for long chain
propoxylates and 160o
C for shot chain propoxylates
10.The liquid alkylene oxides first comes into contact with nitrogen atmosphere
and then gets pulled in to the liquid flow (raw material)
11.EO/PO is fed at >175 psi
12.After feeding the stoichiometric amount of reactants the feed line is closed
and feed line is buffered with nitrogen (nitrogen pressure is set at a higher
pressure).
13.After this the temperature in the loop reactor is increased by 10o
C
14.Any residual EO/PO is reacted by this process (20 minutes for ethoxylates
(<1ppm) and 1.5-2 hours for propoxylates (50ppm))
15.After this the loop pump is stopped and the catalyzed product is discharged to
the final treatment
Final treatment
RX (CH2CH2O)n CH2CH2O¯ + H+
RX(CH2CH2O)n + 1H
a. Charging the catalyzed product to final treatment vessel
b. Cooling down the mixture to room temperature
c. Adding the neutralizing acid
d. Taking a sample and checking pH
e. Applying vacuum to degas the neutralized product
f. Cooling to room temperature
g. Discharging to the filter or to storage tank

10. 10
1. The treatment vessel consists of a stirred vessel with external circulating
pump and a heat exchanger. The vessel is connected with vacuum of 50psi
and temperature 200o
C
2. The catalyzed product is cooled to 100oC, neutralized, degassed and further
cooled down
3. The acid (acetic acid/lactic acid for ethoxylates and phosphoric acid for
propoxylates) Is metered to neutralize
4. After neutralizing a sample is taken and pH checked. The cloud point of the
sample is also checked
5. If necessary OH value should be checked for longer reaction time products
6. After completing quality check, the batch is further cooled to storage
temperature and the product degassed by vacuum at <20torr
7. If the product needs PO value of <5ppm, then strip the product with nitrogen
or steam through the jet mixer
8. If bleaching is required then H2O2 may be used. Feed the peroxide through jet
mixer
9. Transfer the quality checked product to storage facility.
10.If any salt is found in the product then filter using M-type filter.

11. 11
Dr. Muller filter

12. 12
High molecular weight alkoxylates
Higher molecular weight alkoxylates can be produced in one step process by using
two loops. Addition of 30 to 45 EO/PO molecules is possible by using two loops.
Other types of catalysts used are
1. Strontium hydroxide/ calcium hydroxide/aluminum hydroxide
2. Magnesium hydroxide
3. Antimony chlorides
4. Rare earths

13. 13
Etherified resin polypropylene glycol alkoxylate
Procedure for the preparation of a new type of demulsifier is given below. More
products will be added now and then.
Product A- Condensation of Phenol and Formaldehyde
1. Phenol…………………….94.1g (1mole)
NaOH (50%) ………… 03.1g
2. Place above materials in a flask which can be fitted with stirrer, thermometer,
distillation, etc
3. Heat the flask with contents to 55-60o
C
4. Formaldehyde (35% )……………..171g (2mole)
5. Add formaldehyde slowly to keep the temperature at 55-60 o
C
6. When the formaldehyde was added completely heat to 70 o
C until free from
formaldehyde is < 2%
Product B- Alkoxylation of polypropylene glycol
7. Polypropylene glycol (Mol Weight 2000)…. 400g (0.2Mole)
KOH (85%)……………………………………… 2.5g
8. Dry the PPG with KOH at 110 o
C for 2hrs
9. Ethylene oxide (EO) 240g (240x100/400 =60% of PPG) (5.45mole)
10.Meter EO at 130 o
C -140 o
C
Condensation of product A &B- Etherification
11.A……………………..80g (0.3mole)
B……………………640g (0.2mole)
12.Mix A and B with stirring
13.Neutralize with DDBSA
14.Mole ratio A to B is 1.5:1
15.Reduce vacuum to 2000mPa (0.015mmHg) at 80-85 o
C
16.Distill out water under vacuum.
17.The mixture is etherified by increasing the temperature to 140 o
C
18.Remove water
Oxypropylation of etherified condensate
19.Condensate (etherified product)……………..325g
KOH (85%) ……………………………………………3.8g
20.Heat the mixture to 100-120 o
C

14. 14
21.Dry the mixture at a vacuum of 2000mPa (0.05mmHg) for 2hrs
22.PO…………………630g (194g epoxide per 100g condensate)
23.Meter PO at 120-130 o
C and pressure 50-500kPa (7-72psi) for 3hrs
24.Final product is dark liquid
25.Dilute to 50% by Xylene
Require raw materials:
1. Phenol
2. NaOH/KOH
3. Formaldehyde (35%)
4. Polypropylene glycol (mol weight: 2000)
5. Dodecyl benzene sulfonic acid
6. Ethylene oxide
7. Propylene oxide