Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PRODUCTION OF LOW FINE SEDIMENT
HIGH Tl3N PHENATE STEARATE
5 The present invention relates to the production of highly overbased
phenate stearate.
BACKG~OUND OF THE INVENTION
10 The present invention con1es out of work in the production of phenate
stearate having a high Total 13ase Number (TBN). That production is
hampered by the creation of .~ fine sediment. The fine sediment is virtually
os~ le to remove from th~ product by means common to the manufacture
of phenate, such as filtration.
EPO 0,094,814 A2 teach~s improving the stability of an overbased
phenate by treating the phenate with a carboxylic acid having a Cl0 to Cz4
Ul ILI ~1 I.,B ed segment, such as stearic acid.
WO 88/03944 and 88/03~45 teach an overbased phenate having a TBN
of more than 300. This high 1-BN is achieved by using an additional
co",~,,an~"l. either a carboxylic acid, such as stearic acid, or a di- or poly
carboxylic acid having from 36 to 100 carbon atoms, or an anhydride, add
chloride, or ester thereof.
SUMMARY OF THE INVENTION
The present invention provides a process that produces an overbased
sulfurized phenate stearate ~vithout producing fine sediments. That process
controls the degr~e of a~itation and the ratio of ethylene glycol to water
durirlg the overbasing process to prevent the fonmation of fine sediments.
In this process, a mixture having a sulfurized phenate, a metal stearate
(such as calcium stearate), ~t least one solvent, calcium hydroxide, and
water is o ~, L,ased by conta~ting the mixture with carbon dioxide in the
presence of an alkyl polyhydric alcohol. Throughout the overbasing step, the
level of agitation is sufficiently high so that all solids are suspended over the
length of the overbasing step. After the overbasirlg step, the overbased
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mixturQ is stripped io produce an overbased phel1ate stearate having less
than 0.10 vol.% fine sediment~3.
Preferably, the polyhydric alcohol to water ratio is " Idil ddil l~d sufficiently
5 high so that the ratio is at least 4:1 at the end of the overbasing step. Morepreferably, the polyhydric alcohol to water ratio is " ,~.;. I~dil ,ed suffidently high
so that the ratio is at least 9:1 at the end of the overbasing step. Preferably,the overbased phenate stearate has less than 0.05 vol.% fine sediments.
10 The alkyl group of the alcohol has from one to five carbon atoms.
Preferably, the alkyl polyhydric alcohol is ethylene glycol.
The sulfurized phenate to be overbased can comprise a partially
o~u.udsed sulfurized phenate.
BRIEF DESCfi.. I I~N OF THE D~AWINGS
In order to assist the " ,d~rald"-Ji"g of this invention, reference will now
be made to the appended drawings. The drawings are exemplary only, and
20 should not be construed as limiting the invention.
Figure 1 shows how fine ~;ediment varies as a function of degree of
agitation and the weight ratio of ethylene glycol to water at the end of the
Cdl L,~nd~iu,, step in the process, in a reactor operating with poor agitation.
Figure 2 shows how the fine sediment varies as a function of the weight
ratio of ethylene glycol to wa~er at the end of the ,dl Lol~aliol1 step in the
process, in a reactor operating with good agitation.
DETAILED Di-~SCh,. I ION OF THE INVENTION
In its broadest aspect, the present i~vention involves a process for
producing an u ~_, I,ased phenate stearate without the production of fine
se.li",~)la. That process comprises overbasing a mixture that comprises
35 sulfurized phenate, metal st~arate, at least one solvent, calcium hydroxide,
and water, by contacting the mixture with carbon dioxide in the presence of
an alkyl polyhydric alcohol, and strlpping the overbased mixture to produce
an overbased phenate stearate having less than 0.10 vol.% fine sediments.
_ .. . . . . _ _ _
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In order to achieve less th,3n 0.10 vol.% fine sediments, one must
maintain the level of agitation sufficiently high so that all solids are
suspended over the lengih of the u l~. Ldail ,~ step. Preferably, one should
also Maintain a polyhydric alcohol to water ratio surficiently high so that the
5 ratio is at least 4:1 at the end of the overbasing step.
In order to achieve less than 0.05 vol.% fine sediments, one should
maintain a polyhydric alcohol to water ratio suffficiently high so that the ratio
is at least 9:1 at the end of th~ overbasing step.
The alkyl group of the alk~l polyhydric alcohol should have from one to
five carbon atoms. One such useful alkyl polyhydric alcohol is ethylene
glycol. The stearate can calcium stearate, and the sulfurized phenate can
comprises an sulfurized phenate that has been previously overbased.
FINE SEDIMENTS CONTENT
The fine sediment was dele" "i"ed by following a " lo~iri~dliul l of the
ASTM Test Method D 2273 ( Standard Test Method for Trace Sediment in
20 Lubricating Oils). The modified test method consists of filling a centrifuge
tube to the 75 ml mark with n3ptha and adding sufficient final, stripped and
filtered sample to fill the tube to the 100 ml mark. A stopper is placed in the
tube and it is shaken until th~ filtered sample co",~ ,t~ly dissolves in the
naptha. The tube is then pla~ed in a oentrifuge operating at 4000 RPM's.
25 The sample is spun for 15 minutes at 4,000 RPM and then the volume of the
ce"' iCu~d solids at the bottom of the tube is read. The fine sediment in the
sample is calculated as follows:
Volume % Fine = 4 x (ml of sediment read in centrifuge tube).
Sediment in Sample
During the process to produce the high TBN o;~.Lased phenate stearate,
two factors strongly affect th~ quality of the high TBN overbased phenate
s~earate. These factors are:
(1 ) how well the c3rbon dioxide gas is dispersed into the reaction
medium during t~le overbasing step, and
(2) the ratio of the weight percent of ethylene glycol to water in the
reactor at the end of the overbasing step.
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The degree to which the carbon dioxide gas is dispersed, or mixed, into
the reaction depends on the eFfectiveness of the gas-liquid mixing in a
particular reactor. [nyi"ee, i"y analysis of the gas-liquid mixing occuring
during overbasing revealed that one contributing factor to the formation of
5 this fine sediment was localized overoverbasing or inadequate gas-liquid
mixing. During Cdl uu, latiul~, adequate gas-liquid mixing is necessary to
prevent the formation of a fine sediment.
~-GITATION LEVEL
The e~r~uti~ eas of gas-liquid mixing for a specific reactor can be
~,u, t,ssed as an Agitation Scale Level (ASL) value, a term often used in the
industry. Tha ASL value for a given reactor is a function oF reactor diameter,
liquid volume, impeller diame~er, number of impeller blades, impeller blade
15 pitch, impeller blade height, liquid density, liquid viscosity, impeller RPM and
gas flow rate. The ASL scale ranges between 0 and 10 and can be broken
into four groups:
ASL Desuiption
0 Indicates a floaded impeller.
1-2 Provides no, ,n~,u.led impeller con~itions for coarse dispersion
of gas. Typica~:,, ' ' )i are ones in which mass transfer
or gas dispersion is not critical.
3-5 Drives fine bu~bles uulll~ ,~ly to vessel wall and
recirculation of dispersed bubbles back into the impeller.
Gas di~ iu,~ is cul~aid~l~d moderate.
6-10 Provides maximum interfacial area and recirculation of
dispersed bubl~les back into impeller. C~ldld~ ris~ic of gas-
liquid reaction~i where rapid mass transfer is required.
35 We have found that an agitation scale level of 3 would be sufficient to
suspend all solids over the l~ngth of the overbasing step.
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POLYHYDRIC ALCOHOL TO WATER RATIO
During the o:~, Ldsi"~ steps of the reaction, polyhydric alcohol, such as
ethylene slycol, is present in the reactor to aid in reactions taking place.
5 Also during the reaction, wateir is produced by the neutralization reactions
between the calcium hydroxid3 and the alkylphenol and stearic acid and also
between the reaction of calcium hydroxide with cdrbon dioxide. In general,
the bulk of this water is removed during the reaction. As the water is
removed from the reactor, it r~moves some of the ethylene glycol from the
10 reactor as well teven though, in theory, the reactor temperature and pressur~is such that ethylene glycol should not be distilling). This removal of the
ethylene glycol is also increased during the overbasing step if inefficient gas-liquid mixing is present. Also, if good vacuum control is not " ,~,;, lldil ,e~
during the reaction (a~u~ ' lly too high a vacuum is " Idil ,la;. ,ed), too muchwater and ethylene glycol can be removed from the reaction which can result
in the formation of this fine sediment. Consequently, it has been found that
their is an optimum ratio of th~3 weight percent ethylene glycol to water that
should be present in the reacl'or at the end of the overbasing step that
prevents the formation of the fine sediment. The weight percent ethylene
20 glycol and water present in the reactor is d~tt:l",i"ed by removing a sample
of the reactor contents and subjecting the sample to an d~t:Ytl u,uic distillation
using Xylene and collecting t~le distillate which ~herl contains the ethylene
glycol and water as a separate phase. The amount of ethylene glycol
present in this separate phas 3 is d~l~l " ,i"ed by refractive index.
EXAMPLES
The invention will be further illustrated by following examples, which set
forth particularly advantageous method ~",~odi",e"~ .. While the Examples
30 are provided to illustrate the l~resent invention, they are not intended to
limit it.
EXAMPLE 1
To a clean 4,0û0 gallon ( 15,151 liters) reactor equipped with a variable
speed agitator, operating to provide a sufficiently high level of agitation so
that all solids are suspended over the length of the overbasing step, were
charged 3,654 pounds (1,657 kilograms) of diluent oil, 7,435 pounds
.. . . .. ... _ .. ~ . .. , . . _ = _ _ _
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(3,372 kilograms) of decyl alcohol, 483 pounds ~219 kilograms) of ethylene
glycol, 4,825 pounds (2,188 ~ilograms) of dodecyl phenol, 2,760 pounds
(1,251 kilograms) of calcium hydroxide, and 150 pounds (68 kilograms) of
calciurrl chloride dihydrate with the agitator tumed on at ~,.,u, UAil I ,..t~,ly 75F
5 (24 C). To this mixture was then added 3,100 l~ounds (1,406 kilograms) of
solid stearic acid. The contents of the reactor wers heated to 150 F (65 C).
When the raactor t~""~e, ' ~e reached 150 F i 10 F (65 C i 5 C), an
additional 2,760 pounds (1,251 kilograms) of calcium hydroxide was charged
to the reactor. The reactor pressure was then " ,~ dil ,ed at 4.0 i 0.2 psia
10 (0.28 ~ 0.014 kg/cm2) of vacl~um with the sour gas system.
The reactor was heated to 290 F i 5 F (143 C i 2 C) over 1.5 i 0.25
hours. When the reactor realched 290 F ~ 5F, 803 pounds (364 kilograms)
of liquid sulfur was charged ~o the reactor and allowed to mix for 1û - 2û
15 minutes to ensure complete tl l~,UI ~UUI elLiul~ of the sulfur into the reactor. The
reactor was then heated to 300 F (148 C). When the reactor conlents
reached 300 F i 5 F (148 C i 2 C), 58û pounds (263 kilograms) of
ethylene glycol was added over 1.5 hours while the reactor was heated to
350 Fi 5 F (176 C i 2 C). When the reactor reached 350 Fi 5 F, 1,802
20 pounds (817 kilo5rarns) of carbon dioxide was added at a rate of
9.68 pounds/minute (4.39 hiloy~ a/~ ute) sirnultaneoulsy while adding
1,152 pounds (522 kilogram.~) of ethylene glycol at a rate of
6.4 pounds/minute (2.9 kiloy, ~, lla/~ l lil "~te) over 3 hours. When the carbondioxide and ethylene glycol ~3dditon was complete, 468 pounds
25 (212 kilograms) of carbon di~xide was added at a rate of 3.9 pounds/minute
(1.8 hil~yl~",~ "i"~te) over 2 hours. At the end of the overbasing step, a
1 quart (0.946 liter) sample ~vas removed from the reactor and the water and
ethylene glycol In a 100 gram aliquot of this sample was subjected to
ullu,l~ic distillation to afford 2.6 mls of azeotrope. The ethylene glycol
30 content of this azeotrope was d~ l ",i"ed by refractive index to be 90.0 %, or
2.3 grams of ethylene ylycal. The remaining mass of the azeotrope,
0.30 grams, I~,ult:a~ d the water content of the azeotrope. The ethylene
glycol to water weight ratio, therefore, was 9Ø At the end of this second
carbon dioxide addition, rerr~aining water, produced from the neutralization
35 reactions between alkylpherlol and stearic acidl with calcium hydroxide and
the reaction of calcium hydr~xide with carbon dioxide, and remaining
ethylene glycol was remove~d by vacuum distillation. This was acc~" ,,uali~l ,edby reducing the vacuum in tl,le reactor to 5.9 psia i 1 psia (0.41 i 0.007
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21 8390S
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kglcm2) gradually over a peric~d of 30 minutes while " Id;l Itdil lil ,g the
temperature at 350 F i 5 F ~176 C i 2 C). Following this removal of the
water and ethylene glycol, the raactor distillation recaiver was changed and
the decyl alcohol solvent, and residual ethylene glycol, was removed from the
reaction by further vacuum distillation. To ~r~ C~ 11 this, the reactor
vacuum was reducad to 0.5 - 1.5 psia (0.035 - 0.11 kg/cm2) gradually over 30
minutes while heating the real,tor temperature to 425 F i 5 F
(218 C i 2 C) . When the reactor reached 425 F i 5 F and 0.5 - 1.5 psia,
it was held for 1.5 hours.
Following this second distillation, the reactor vacuum was broken with
purge nitrogen and the reactar was cooled to 350 Fi 5 F (176 C i 2 C),
and the contents of the reactc~r (18,603 pounds or 8,438 kilograms) was
pumped to a storage tank. F~llowing this, 718 pounds (325 kilograms) of
diluent oil was flushed throug~ the reactor and pump into the storage tank.
The product in the storag~ tank was then filtered through a Schenk filter
with the aid of a filter aid to afford a prduct with the following average
~,u,u~,l;as. TBN = 387, Ca = 14.3 %, S = 2.15 %, C02 = 10.3 %, SlCa = 0.15,
C02/Ca = 0.72, Viscosity = 377 cSt (100 C) and sediment 0.02 Vol. %.
EXANIPLE 2
Referring to Figure 1, a series of runs were made to show how fine
25 sediment varies as a function of degree of agitation and the weight ratio of
ethylene glycol to water (EG/H2O) at the end of the Cdl l,or,dliu,~ step in the
process, in a reactor operatir g with poor agitation (an Agitation Scale Level
of be~ween 1 and 2). Figure 1 shows that as the EG/H20 ratio increases; the
level of fine sediment decreases dldll. - 1l~. For example, at an EG/H20
30 ratio of 4.7, a hne sediment content of 5.9 volume % is observed while at an
EG/H20 ratio of 9.0, an average fine sediment of 0.026 volume % is observed
(average of three different re~ctions showing O.û2, 0.02 and 0.04 volume %
fine sediment).
35 Figure 2 shows how the fine sediment varies as a function of the weight
ratio of ethylene glycol to wa~er (EG/H2O) at the end of the C,dl bUI IdliUn step
in the process, in a reactor operating with good agitation (an Agitation Scale
Level of between 3 and 4). Figure 2 shows that as the EGIH20 ratio
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increases; the level of fine sediment cle,,, ~:ases but not as ~I dl I IdliWIIy as
when an the reactor is operatin3 at a low ASL level (between 1 and 2 - see
Figure 1). For example, Fig-lre 2 shows that with an EG/H20 ratio oF 4.0, the
flne water.sedime~t content is 0.14 volume % while at an EG/H20 ratio of 7.3,
5 a 0.04 volume % fine sediment is observed.
While the present inventicn has been described with reference to speciflc
bo.li~ ,ts, this ,, ' " , is intended to cover those various changes
and s~ ti~ns that may be made by those skilled in the art without
10 departing from the spirit and scope of the appended claims.
