U.S. patent application number 10/850537 was filed with the patent office on 2005-11-24 for dispersant material for mitigating crude oil fouling of process equipment and method for using same.
Invention is credited to Baxter, C. Edward JR., Dickakian, Ghazi B., Truong, Jeffrey Quoc.
Application Number | 20050261440 10/850537 |
Document ID | / |
Family ID | 35376067 |
Filed Date | 2005-11-24 |
United States Patent
Application |
20050261440 |
Kind Code |
A1 |
Dickakian, Ghazi B. ; et
al. |
November 24, 2005 |
Dispersant material for mitigating crude oil fouling of process
equipment and method for using same
Abstract
An improved dispersant material for mitigating crude oil fouling
comprises a reaction product of a polyamine and a polyisobutylene
succinyl anhydride made with a polyisobutylene having a vinylidene
double bond content of at least 50%. The reaction product has an
active nitrogen atom content of at least about 2% by weight. The
reaction product is prepared by thermally reacting the
polyisobutylene with maleic anhydride to produce said
polyisobutylene succinyl anhydride and thereafter reacting the
polyisobutylene succinyl anhydride with a polyamine having 5 to 7
active nitrogen atoms.
Inventors: |
Dickakian, Ghazi B.;
(Kingwood, TX) ; Baxter, C. Edward JR.; (League
City, TX) ; Truong, Jeffrey Quoc; (Houston,
TX) |
Correspondence
Address: |
STINSON MORRISON HECKER LLP
ATTN: PATENT GROUP
1201 WALNUT STREET, SUITE 2800
KANSAS CITY
MO
64106-2150
US
|
Family ID: |
35376067 |
Appl. No.: |
10/850537 |
Filed: |
May 20, 2004 |
Current U.S.
Class: |
525/333.7 |
Current CPC
Class: |
C08F 8/32 20130101; C10L
1/2383 20130101; C10L 10/04 20130101; C08F 10/10 20130101; C08F
8/32 20130101; C10L 1/221 20130101; C10L 10/06 20130101 |
Class at
Publication: |
525/333.7 |
International
Class: |
C08F 010/00 |
Claims
We claim:
1. A dispersant material for mitigating crude oil fouling
comprising a reaction product of a polyamine and a polyisobutylene
succinyl anhydride made with a polyisobutylene having a vinylidene
double bond content of at least 50%, said reaction product having
an active nitrogen atom content of at least about 2% by weight.
2. A dispersant material as set forth in claim 1, wherein said
reaction product is prepared by thermally reacting said
polyisobutylene with maleic anhydride to produce said
polyisobutylene succinyl anhydride and thereafter reacting the
polyisobutylene succinyl anhydride with a polyamine having 5 to 7
active nitrogen atoms.
3. A dispersant material as set forth in claim 1, wherein said
reaction product has a number average molecular weight which ranges
from about 400 to about 5000.
4. A dispersant material as set forth in claim 3, wherein said
reaction product has a number average molecular weight which ranges
from about 500 to 2500.
5. A dispersant material as set forth in claim 1, wherein the
active nitrogen atom content thereof is at least about 4% by
weight.
6. A dispersant material as set forth in claim 1, wherein the
active nitrogen atom content thereof is at least about 6% by
weight.
7. A dispersant material as set forth in claim 2, wherein said
reaction product is prepared by reacting said polyisobutylene
succinyl anhydride with a polyamine at a molar ratio within the
range of from about 0.5:1 to about 5:1.
8. A dispersant material as set forth in claim 1, further
comprising one or more of a second dispersant material, an
antioxidant, an antipolymerant, a metal chelating chemical, a
hydrocarbon solvent and an oxygen, nitrogen, sulfur or chlorine
containing solvent.
9. A crude oil composition wherein fouling has been mitigated
comprising crude oil and an anti-fouling amount of a dispersant
material as set forth in claim 1 dispersed in said crude oil.
10. A crude oil composition as set forth in claim 9, comprising
from about 1 ppm to about 500 ppm of said dispersant material.
11. A crude oil composition as set forth in claim 9, comprising
from about 5 ppm to about 200 ppm of said dispersant material.
12. A crude oil composition as set forth in claim 9, comprising
from about 10 ppm to about 150 ppm of said dispersant material.
13. A method for mitigating crude oil fouling comprising: providing
a dispersant material comprising a reaction product of a polyamine
and a polyisobutylene succinyl anhydride made with a
polyisobutylene having a vinylidene double bond content of at least
50%, said reaction product having an active nitrogen atom content
of at least about 2% by weight; dispersing said dispersant material
in crude oil wherein fouling is to be mitigated; and subjecting
said crude oil to processing in an environment conducive to the
occurrence of fouling.
14. A method as set forth claim 13, wherein said reaction product
is prepared by thermally reacting said polyisobutylene with maleic
anhydride to present said polyisobutylene succinyl anhydride, and
thereafter reacting the polyisobutylene succinyl anhydride with a
polyamine having 5 to 7 nitrogen atoms.
15. A method as set forth in claim 13, wherein said reaction
product has a number average molecular weight which ranges from
about 400 to about 5000.
16. A method as set forth in claim 15, wherein said reaction
product has a number average molecular weight which ranges from
about 500 to 2500.
17. A method as set forth in claim 13, wherein said dispersant
material has an active nitrogen atom content of at least about 4%
by weight.
18. A method as set forth in claim 13, wherein said dispersant
material has an active nitrogen atom content of at least about 6%
by weight.
19. A method as set forth in claim 14, wherein said reaction
product is prepared by reacting said polyisobutylene succinyl
anhydride with a polyamine at a molar ratio within the range of
from about 0.5:1 to about 5:1.
20. A dispersant material for mitigating crude oil fouling
comprising a reaction product of a polyisobutylene succinyl
anhydride and a polyamine, wherein said polyisobutylene succinyl
anhydride is characterized by having been prepared by thermally
reacting a polyisobutylene with maleic anhydride, said reaction
product having an active nitrogen content of at least about 2% by
weight.
21. A dispersant material as set forth in claim 20, wherein said
polyamine has from 5 to 7 nitrogen atoms.
22. A dispersant material as set forth in claim 20, wherein said
reaction product has a number average molecular weight which ranges
from about 400 to about 5000.
23. A dispersant material as set forth in claim 22, wherein said
reaction product has a number average molecular weight which ranges
from about 500 to 2500.
24. A dispersant material as set forth in claim 20, wherein the
active nitrogen atom content thereof is at least about 5% by
weight.
25. A dispersant material as set forth in claim 20, wherein the
active nitrogen atom content thereof is at least about 6% by
weight.
26. A dispersant material as set forth in claim 21, wherein said
reaction product is prepared by reacting said polyisobutylene
succinyl anhydride with a polyamine at a molar ratio within the
range of from about 0.5:1 to about 5:1.
27. A dispersant material as set forth in claim 20, further
comprising one or more of second dispersant material, an
antioxidant, an antipolymerant, a metal chelating chemical, a
hydrocarbon solvent and an oxygen, nitrogen, sulfur or chlorine
containing solvent.
28. A crude oil composition wherein the tendency for fouling has
been mitigated comprising crude oil and an antifouling amount of a
dispersant material as set forth in claim 20 dispersed in said
crude oil.
29. A crude oil composition as set forth in claim 28, comprising
from about 1 ppm to about 500 ppm of said dispersant material.
30. A crude oil composition as set forth in claim 28, comprising
from about 5 ppm to about 200 ppm of said dispersant material.
31. A crude oil composition as set forth in claim 28, comprising
from about 10 ppm to about 150 ppm of said dispersant material.
32. A method for mitigating crude oil fouling comprising: providing
a dispersant material comprising a reaction product of a polyamine
and a polyisobutylene succinyl anhydride made with a
polyisobutylene having a vinylidene double bond content of at least
50%, said reaction product having an active nitrogen atom content
of at least about 2% by weight; and dispersing said dispersant
material in a crude oil wherein fouling is to be mitigated.
33. A method for mitigating crude oil fouling as set forth in claim
32, wherein said polyisobutylene succinyl anhydride is
characterized by having been made by a thermal process.
34. A dispersant material as set forth in claim 1, wherein said
reaction product is prepared by thermally reacting said
polyisobutylene with maleic anhydride to present said
polyisobutylene succinyl anhydride.
35. A dispersant material as set forth in claim 20, wherein the
active nitrogen atom content thereof is at least about 3% by
weight.
36. A dispersant material as set forth in claim 20, wherein the
active nitrogen atom content thereof is at least about 4% by
weight.
37. A dispersant material as set forth in claim 1, wherein the
active nitrogen atom content thereof is at least about 3% by
weight.
38. A dispersant material as set forth in claim 1, wherein the
active nitrogen atom content thereof is at least about 5% by
weight.
39. A dispersant material as set forth in claim 1, wherein said
polyisobutylene succinyl anhydride is made with a polyisobutylene
having a vinylidene double bond content of at least 60%.
40. A dispersant material as set forth in claim 1, wherein said
polyisobutylene succinyl anhydride is made with a polyisobutylene
having a vinylidene double bond content of at least 70%.
41. A dispersant material as set forth in claim 1, wherein said
polyisobutylene succinyl anhydride is made with a polyisobutylene
having a vinylidene double bond content of at least 80%.
42. A dispersant material as set forth in claim 1, wherein said
polyisobutylene succinyl anhydride is made with a polyisobutylene
having a vinylidene double bond content of at least 90%.
43. A dispersant material as set forth in claim 1, wherein said
polyisobutylene succinyl anhydride is made with a polyisobutylene
having a vinylidene double bond content that is greater than
90%.
44. A method for mitigating crude oil fouling as set forth in claim
32, wherein said reaction product has an active nitrogen atom
content greater than 4.8% by weight.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] None
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to dispersant materials useful
for mitigating and/or inhibiting fouling of equipment used for
handling and/or treating liquid hydrocarbons such as crude oil and
the like, and particularly to improved antifoulant materials based
on a reaction product of a hydrocarbon long chain such as
polyisobutylene (PIB), a bridging agent such as maleic anhydride
and a substance having a polar group such as a polyamine (PAM).
Such products are sometimes referred to generically as PIBSA-PAMs.
The invention also relates to methodology useful for mitigating the
fouling tendencies of crude oils and the like which includes the
addition of an improved fouling mitigating and/or inhibiting
dispersant material thereto. Furthermore, the invention relates to
improved crude oil compositions wherein fouling tendencies have
been mitigated by the presence therein of improved fouling
mitigating and/or inhibiting dispersant materials.
[0004] 2. Background of the Invention
[0005] Crude oil is complex mixture composed of many components
which vary greatly in their chemical and physical properties. The
basic components of crude oils include saturated hydrocarbons,
naphthenes, resins, aromatics and macromolecular asphaltenes. Crude
oils are classified as naphthinic, aromatic or paraffinic,
depending upon the relative concentrations of these ingredients.
Asphaltenes are present in most crude oils; however, the
concentration thereof may vary from about 0.1 wt % to as much as 12
wt %, depending on the origin of the crude. Asphaltenes are highly
aromatic conglomerates with very high molecular weights, and the
same may generally be characterized as alkyl aromatics consisting
of polycondensed aromatics of six or more rings. Asphaltenes are at
least partially soluble in aromatics. However, the same are
generally insoluble in saturated hydrocarbons, and, as a result,
asphaltenes usually exist in crude oils in the form of a suspension
that is stabilized by the resin fraction which acts as a natural
dispersant.
[0006] As is well known in the petrochemical industry, in order to
beneficiate crude oils and produce valuable commercial products
therefrom, it is generally necessary to subject the crude oil
materials to distillation and/or cracking operations, or the like,
wherein the crude oil materials are subjected to high temperatures.
However, when crude oils, and particularly those that are deficient
in aromatics and/or resins, are subjected to the high temperatures
needed for processing, the asphaltenes and other undesirable
carbonaceous materials become incompatible with the liquid phase
and tend to flocculate and/or precipitate so as to deposit and
accumulate on hot metal internal surfaces of processing equipment.
This accumulation of undesirable carbonaceous materials on the
internal surfaces of process equipment is often referred to as
"fouling." And fouling often causes serious operational problems
such as reduced heat transfer efficiency and increased pressure
drop characteristics. In fact, in some cases fouling is of
sufficient magnitude to totally block flow through the equipment.
Moreover, fouling often may be the cause of increased metal
corrosion.
[0007] Needless to say, the fouling of process equipment such as
heat exchangers and/or furnace tubes, for example, is a costly
problem in refineries and petrochemical plants and the like, since
the fouled equipment must be dismantled, cleaned and reassembled.
Such cleaning operations are not only tedious and costly, but
result in a large amount of "downtime" during which the units are
not functioning.
[0008] It is known that certain dispersants of specific chemical
structure can mitigate and/or inhibit fouling of process equipment
by crude oils and the like. Such dispersants generally function to
disperse and suspend in the liquid phase undesirable carbonaceous
materials such as asphaltene macromolecules that form during
heating of the crude oil. Thus, these dispersants inhibit and/or
prevent the accumulation of undesirable carbonaceous materials on
the internal surfaces of the equipment. Generally speaking, these
known dispersants have polar atoms which may function to chelate
with the undesirable carbonaceous materials to thereby assist in
the dispersion of the same in the liquid phase. Accordingly, the
undesirable carbonaceous materials are kept in suspension and not
allowed to flocculate out for accumulation on the internal surfaces
of the process equipment.
[0009] Known dispersants for mitigating fouling during processing
of crude oils and the like often include a long chain hydrocarbon
portion to provide solubility of the dispersant in oil and a polar
functionality group providing an active site capable of chelation
with undesirable carbonaceous materials such as asphaltene
macromolecules, whereby the latter are kept in a suspended,
dispersed condition in the crude oil. These polar functionality
groups often include oxygen and/or nitrogen atoms which facilitate
efficient chelation and the resultant dispersion of the asphaltene.
Known dispersants may also desirably have low viscosity and good
thermal stability to appropriately withstand the hostile
environment in which the same are utilized.
[0010] Polyisobutylene succinyl anhydride-polyamine compounds,
which are often referred to as PIBSA-PAM compounds, are well known
and have been used for many years as dispersants, both for
dispersing oxygenated sludge in automotive engines and mitigating
fouling during crude oil processing operations. The commercially
available PIBSA-PAM compounds generally have a number average
molecular weight (MN) within the range of from about 500 to about
2000, a nitrogen atom content within the range of from about 1.0 to
about 4.0 weight % and a total base number within the range of from
about 40 to about 60 mg KOH per gram of PIBSA-PAM compound. In the
past, these commercially used PIBSA-PAM compounds have been made by
reacting a conventional PIB with maleic anhydride or the like using
a chlorine facilitated process to produce a polyisobutylene
succinyl anhydride (PIBSA). That is to say, the known PIBSA-PAM
compounds are generally produced by first reacting a conventional
PIB with maleic anhydride at elevated temperatures in the presence
of chlorine gas. The PIBSA so produced is then condensed with a
polyamine (PAM) having a plurality of polar nitrogen atoms.
[0011] The production of PIBSA using conventional PIB takes place
as follows: 1
[0012] Conventional PIB products are generally produced using an
AlCl.sub.3 catalyst, and about 65% of the molecules of the
polymeric product have double bonds that are 1,2,2-trisubstituted.
The remainder of the molecules of the polymeric product have double
bonds that are highly substituted, internal, and relatively
non-reactive. The 1,2,2-trisubstituted double bonds are somewhat
reactive in a thermal, chlorine facilitated reaction with maleic
anhydride, whereas the highly substituted internal double bonds are
essentially non-reactive with maleic anhydride. The PIBSA products
are generally of low quality with high color and considerable char.
Active PIBSA yields are generally less than 70%. Moreover, when
reacting conventional PIB with maleic anhydride using a
conventional "ene" reaction mechanism, it is possible to attach
only one maleic anhydride group to each PIB molecule. This limits
the number of polar nitrogen atoms that can be incorporated into
each molecule of a conventional PIBSA-PAM dispersant. As a
consequence of these things, the efficiency of the conventional
dispersants for purposes of inhibiting and/or mitigating fouling is
limited. Methodology for producing PIBSA-PAM products where the
PIBSA is prepared by reacting conventional PIB with maleic
anhydride in the presence of chlorine is described in U.S. reissue
patent no. Re. 26,330 (the "'330 reissue patent").
[0013] More recently, processes have been developed for producing
what has become known as highly reactive polyisobutylene (HR-PIB).
In HR-PIB, a predominant portion of the molecules of the polymeric
product have double bonds which are in a vinylidene terminal
(alpha) position. Generally speaking, in commercial grades of
HR-PIB, about 83 to 85% of the double bonds are in a vinylidene
position. These vinylidene double bonds react readily with maleic
anhydride under thermal reaction conditions to produce PIBSA
products, and in general, PIBSA yields are 10 to 15% greater than
when conventional PIB is utilized. Methodology for preparing PIBSA
using HR-PIB as a reactant is described in European patent
application no. 0 355 895 (EP '895), which also discusses the use
of such PIBSA to make PIBSA-PAM. However, EP '895 does not discuss
the use of the PIBSA-PAM as a dispersant for inhibiting or
mitigating fouling of process equipment used for processing crude
oils or the like. Moreover, the nitrogen content of the PIBSA-PAM
described in EP '895 is quite low and in each case is far less than
2%.
SUMMARY OF THE INVENTION
[0014] A principal object of the invention is to provide an
improved dispersant material for inhibiting and/or mitigating crude
oil fouling of process equipment. In particular it is an object of
the invention to provide an improved dispersant having a chemical
makeup which facilitates the incorporation therein of an increased
number of polar sites capable of chelating with undesirable
carbonaceous materials contained in crude oils and the like.
Furthermore, it is an object of the invention to provide an
improved high quality PIBSA-PAM material which is produced from a
clean, high quality PIBSA made using a PIB having a significant
concentration of vinylidene double bonds. In the sense of the
invention, a clean PIBSA is one which is relatively clear, has a
light color and contains essentially no char or chlorine.
[0015] The problems inherent in the prior art are minimized, if not
eliminated completely, and the foregoing objects are achieved, as a
result of the present invention which provides a PIBSA-PAM
dispersant material for mitigating crude oil fouling in chemical
process equipment comprising a reaction product of a polyamine and
a polyisobutylene succinyl anhydride made with a polyisobutylene
having a vinylidene double bond content of at least 50%. Desirably
the reaction product has an active nitrogen atom content of at
least about 2% by weight. In accordance with the concepts and
principles of the invention, the dispersant material may
advantageously be prepared by thermally reacting the
polyisobutylene with maleic anhydride to produce polyisobutylene
succinyl anhydride. The polyisobutylene succinyl anhydride may
thereafter desirably be reacted with a polyamine having 5 to 7
nitrogen atoms to produce PIBSA-PAM. In further accordance with the
invention, the reaction product may have an MN which desirably
ranges from about 400 to about 5000, and preferably ranges from
about 500 to 2500. In further accordance with the invention, the
active nitrogen atom content of the dispersant may desirably be in
the range of from about 2% to about 12% by weight, and may
advantageously be at least about 3%, 4%, 5%, 6% or more, by weight.
In still further accordance with the invention, the PIBSA-PAM
reaction product may beneficially be prepared by reacting the
polyisobutylene succinyl anhydride with a polyamine at a molar
ratio of polyisobutylene succinyl anhydride to polyamine desirably
within the range of from about 1:1 to about 5:1 and preferably
within the range of from about 2:1 to about 2.5:1. Ideally, the
dispersant material of the invention may include one or more of a
second dispersant material, an antioxidant, an antipolymerant, a
metal chelating chemical, a hydrocarbon solvent and an oxygen,
nitrogen, sulfur or chlorine containing solvent.
[0016] In accordance with another desirable aspect of the
invention, the same provides a crude oil composition wherein
fouling has been mitigated comprising crude oil and an anti-fouling
amount of the improved dispersant material described above
dispersed in the crude oil. In further accordance with this aspect
of the invention, the crude oil composition may desirably include
from about 1 ppm to about 500 ppm (wt) of said dispersant material,
may preferably include from about 5 ppm to about 200 ppm (wt) of
said dispersant material and ideally may include from about 10 ppm
to about 150 ppm (wt) of said dispersant material.
[0017] In another important aspect, the invention provides a method
for mitigating crude oil fouling of chemical process equipment
which includes providing a dispersant material comprising a
reaction product of a polyamine and a polyisobutylene succinyl
anhydride made with a polyisobutylene having a vinylidene double
bond content of at least 50%, said reaction product having an
active nitrogen atom content of at least about 2% by weight; and
dispersing the dispersant material in a crude oil wherein fouling
properties are to be mitigated.
[0018] In another important aspect, the invention provides a
dispersant material for mitigating crude oil fouling in process
equipment comprising a reaction product of a polyamine and a
polyisobutylene succinyl anhydride, wherein the polyisobutylene
succinyl anhydride is made by a thermal process, and the reaction
product has an active nitrogen content of at least about 2% by
weight. Preferably, in accord with this aspect of the invention,
the polyamine has from 5 to 7 nitrogen atoms. The dispersant of
this aspect of the invention preferably has an active nitrogen atom
content of at least about 5% by weight and ideally has an active
nitrogen atom content of at least about 6% by weight.
[0019] In accordance with yet another aspect of the invention, a
crude oil composition is provided wherein the fouling
characteristics thereof are mitigated. In accordance with this
aspect of the invention, the composition comprises crude oil and an
anti-fouling amount of an improved dispersant material as described
above dispersed in the crude oil. In further accord with this
aspect of the invention, the crude oil composition preferably
comprises from about 1 ppm to about 200 ppm (wt) of the dispersant
material, desirably comprises from about 5 ppm to about 100 ppm
(wt) of the dispersant material and ideally comprises from about 10
ppm to about 25 ppm (wt) of the dispersant material.
[0020] In yet another important aspect, the invention provides a
method for mitigating crude oil fouling comprising providing a
dispersant material comprising a reaction product of a
polyisobutylene succinyl anhydride and a polyamine, said
polyisobutylene succinyl anhydride characterized by having been
made by a thermal process, said reaction product having an active
nitrogen atom content of at least about 2% by weight, desirably
greater than about 4.8% by weight, preferably at least about 5% by
weight, and ideally at least about 6% by weight; and dispersing
said dispersant material in a crude oil wherein fouling is to be
mitigated.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] As mentioned above, the present invention provides an
improved dispersant material for mitigating crude oil fouling of
process equipment. In particular the invention provides an improved
dispersant having a chemical makeup which facilitates the
incorporation therein of an increased number of polar sites capable
of chelation with undesirable carbonaceous materials such as
asphaltenes contained in crude oils and the like. Furthermore, the
invention provides an improved high quality PIBSA-PAM antifoulant
dispersant material which is produced from a clean, high quality
PIBSA produced from a PIB having a significant concentration of
vinylidene double bonds. In the sense of the invention, a clean
PIBSA is one which is relatively clear, has a light color, and
contains essentially no char or chlorine.
[0022] Valuable PIB compositions having significant concentrations
of vinylidene double bonds that are highly useful in connection
with the present invention are fully described in U.S. Pat. No.
6,562,913 (the "'913 patent"). Other valuable PIB compositions
having utility in connection with the present invention are fully
described in United States patent publication no. U.S. 2002/0197497
A1 (the "'497 patent publication"). The entireties of the
disclosures of the '913 patent and the '497 patent publication are
hereby incorporated into the disclosure of the present application
by this specific reference thereto. The '895 European patent
application mentioned above also describes PIB compositions having
significant concentrations of vinylidene double bonds that are
useful in connection with the present invention.
[0023] In accordance with the concepts and principles of the
present invention, the methodology used for preparing the PIB
compositions useful in connection with the present invention is not
critical. The only critical feature of the PIB compositions is that
the same should include significant concentrations of polymeric
molecules having vinylidene double bonds. Preferably, the molar
concentration of molecules of having vinylidene double bonds in the
overall PIB composition should be at least 50%, and desirably and
ideally, this concentration may be 60%, 70%, 80%, 90% or even
greater, without deviating from the overall purposes and objects of
the invention. Moreover, the PIB compositions useful in accordance
with the invention should preferably have an MN in the range of
from about 350 to about 5000, more preferably in the range of from
about 600 to about 4000, desirably in the range of from about 700
to about 3000, even more desirably in the range of from about 800
to about 2000, and ideally in the range of from about 900 to about
1050. In a highly preferred form of the invention, the PIB
composition may have an M.sub.N of about 950.
[0024] Generally, and in further accordance with the concepts and
principles of the invention, the PIB compositions described above
may desirably be reacted with maleic anhydride to form PIBSA
products. The production of PIBSA using HR-PIB and a 1:1 molar
ratio or slight excess of maleic anhydride takes place according to
the following reaction scheme: 2
[0025] Desirably the PIBSA forming reaction follows a "thermal"
route such as is described in EP '895, where the PIB and the maleic
anhydride are simply mixed and heated together. Such a process
minimizes the opportunity for chlorine residues to be present in
the PIBSA. When PIB products that include significant
concentrations of polymeric molecules having vinylidene double
bonds are reacted with maleic anhydride using a "thermal" route,
the maleic anhydride is used very efficiently, resulting in
products of high quality which are clear, have a light color and
contain essentially no char. Overall PIBSA yields are 10 to 15%
greater than when conventional PIB is utilized.
[0026] When PIB products which include significant concentrations
of polymeric molecules having vinylidene double bonds are reacted
with a substantial excess of maleic anhydride (molar ratio of
maleic anhydride to PIB of say 1.5:1 or greater), the PIBSA may be
caused to include a significant concentration of a di-maleated
product. That is to say, more than one molecule of maleic anhydride
can be incorporated into the PIBSA product for each molecule of
PIB. This facilitates the incorporation of a greater amount of
polyamine into the product, whereby to increase the overall
nitrogen content of the PIBSA-PAM product when the di-maleated
PIBSA is reacted with a polyamine. The di-maleated PIBSA product is
believed to have the following molecular configuration: 3
[0027] With reference to the foregoing, it has been noted in
accordance with the present invention that the ability of a
dispersant material to mitigate and/or inhibit crude oil fouling of
process equipment may be enhanced by incorporating therein a larger
number of polar sites capable of chelating with the undesirable
carbonaceous materials contained in crude oils and the like.
Needless to say, di-maleated PIBSA products have twice as many
locations as conventional PIBSA where the same are reactive with
polar nitrogen containing polyamines. Accordingly, the capacity of
the PIBSA for taking on polar sites by reaction with polyamines is
substantially enhanced. However, it is to be understood that in
accordance with the broad aspects of the invention, it is not
necessary for the PIBSA product to be di-maleated in order to
achieve the benefits of the invention. Accordingly, the molar ratio
of polyamine to PIB in the PIBSA of the invention may desirably
range from 0.5:1 or less to as much as a theoretical value of 2:1
if the PIBSA is made from a PIB wherein 100% of the double bonds
are vinylidene and each PIB molecule is di-maleated. More
conveniently, the molar ratio of polyamine to PIB in the PIBSA of
the invention should be in the range of from about 1:1 to about
1.5:1. With further reference to the foregoing, and in further
accordance with the invention, the average number of maleic
anhydride groups per molecule of PIB in the PIBSA should desirably
range from about 0.5:1 to about 2:1. And ideally should range from
about 1:1 to about 1.5:1.
[0028] In further accordance with the concepts and principles of
the invention, the PIBSA materials discussed above are reacted with
polyamines to form PIBSA-PAM substances. A great number of
potentially suitable polyamine compounds are discussed in the '330
reissue patent identified above; however, the preferred amines for
purposes of the present invention are the ethylene amines such as
triethylenetetramine, tetraethylenepentamine and
pentaethylenehexamine. A particularly valuable ethylene amine
material for use in accordance with the invention is a commercially
available product of Dow Chemical Company which is known as Heavy
Polyamine X (HPA-X). HPA-X is a complex mixture of linear,
branched, and cyclic ethyleneamines, the principal components of
which include triethylenetetramine (<2.0 wt %),
tetraethylenepentamine (2-25 wt %), pentaethylenehexamine (15-55 wt
%) and higher molecular weight ethyleneamines (30-75 wt %). On the
average, each molecule of HPA-X has 6.64 nitrogen atoms, and the
same has a molecular weight of approximately 275 g/mole.
Accordingly, the nitrogen content of HPA-X is about 33.8 wt %. Here
also, the exact ratio of PIBSA to PAM is not critical, and the
same, when expressed in terms of the molar ratio of the PAM to the
maleic anhydride moieties of the PIBSA, may desirably range from
about 0.5:1 to about 1:1.
[0029] It should further be noted in connection with the invention
described and discussed above, that sometimes fouling resulting
from crude oil processing may be caused by more than one mechanism.
In such cases, it is sometimes convenient and efficient to use a
combination of dispersant chemicals. That is to say, the improved
PIBSA-PAM of the invention may sometimes desirably be combined with
other chemical additives to provide a multi-functional additive to
perform dispersing as well as other functions. Chemicals which
might be used with the improved PIBSA-PAM of the invention include,
without limitation, anti-oxidants such as tertiary butyl phenol,
alkyl diphenyl amine, phenyl naphthyl amine and dioctyl diphenyl
amine, antipolymerants such as di-tertiary-butyl cresol, tris-nonyl
phenol phosphite, amino nonyl phosphite, nitroxide and di-phenyl
phosphite, and metal deactivators such as
disalicylidene-1,2-propane diamine.
EXAMPLE I
[0030] A preferred embodiment of an improved, high quality
PIBSA-PAM material produced from a clean, high quality PIBSA made
using a PIB having a significant concentration of vinylidene double
bonds is prepared in the following manner:
[0031] 1. 433 g of an HR-PIB product having an M.sub.N of 950 and
an alpha vinylidene content of 83.6% is charged into glass reactor
and the reactor is heated to 300.degree. F. for 1 hour while a
vacuum and N.sub.2 sweep are applied thereto.
[0032] 2. 67.04 g of Maleic Anhydride at 300.degree. F. is added to
the HR-PIB in the reactor and the reaction mixture is heated to
450.degree. F.
[0033] 3. The reaction mixture is maintained at a reaction
temperature of 450.degree. F. for 4.5 hours and thereafter a vacuum
and N.sub.2 sweep are applied to the reactor for 1 hour to strip
away any unreacted Maleic Anhydride.
[0034] 4. The product is a Polyisobutylene Succinic Anhydride
(PIBSA).
[0035] 5. 309.3 g of the PIBSA thus prepared is transferred to
another glass reactor and heated to 250.degree. F.
[0036] 6. 109.3 g of Heavy Polyamine X at 240.degree. F. is added
over a period of 1 hour to the reactor containing the PIBSA while
the reaction temperature is maintained between 240.degree. F. and
270.degree. F.
[0037] 7. The reaction temperature is then increased to 280.degree.
F. and held at that level for 1 hour and 20 minutes.
[0038] 8. The reaction temperature is then increased to 305.degree.
F. and held at that level for 3 hours and 20 minutes.
[0039] 9. A vacuum and N.sub.2 sweep are applied to the reactor for
1 hour to strip the polyisobutylene succinimide (PIBSA-PAM) product
of residual reactants, etc.
[0040] 10. The final product is analyzed and determined to have a
nitrogen content of 8.9 weight percent %.
[0041] A commercially available PIBSA-PAM product made from
conventional PIB and having a M.sub.N of about 1300 was acquired
for comparison purposes. This material and the improved PIBSA-PAM
prepared in accordance with Example I were subjected to identical
testing to determine the ability of each material to inhibit and/or
mitigate fouling in a chemical process type environment. A Thermal
Fouling Test Method (TFTM) was used for this purpose. The TFTM is
an accelerated test method that is designed to reproduce the
fouling problems experienced in refinery processes or petrochemical
plants. The test temperatures are generally higher than those
actually encountered in a commercial operation so that similar
problems may be reproduced in a shorter, more reasonable period of
time. The TFTM is not an exact simulation of refinery heat
exchanger fouling, but by accelerating fouling through high fluid
temperature, it provides a valuable tool that yields results in a
reasonable time. The TFTM has been shown to correlate well with
plant results and is, therefore, useful for research, investigating
fouling, and developing antifoulants. The test is described in the
literature. Wachel, L. J., "Exchanger Simulator: Guide to Less
Fouling," Hydrocarbon Processing, November 1986, pp. 107-110.
[0042] In summary, the TFTM involves the use of a thermal fouling
tester (TFT) which measures crude oil fouling. In the TFT, a crude
oil sample is circulated through a miniature heat exchanger with a
carbon steel heater tube. The entire TFT system is pressurized to
prevent vaporization of the sample at the high temperatures in the
exchanger. Fouling is determined by measuring the fluid outlet
temperature which varies as a function of deposit formation on the
heater metal surface. A greater temperature degradation indicates a
higher degree of fouling.
[0043] The TFTM is an excellent method for simulating the fouling
which might occur in processing equipment as a result of the
processing of crude oils and the like and for measuring the
efficiency of antifoulant materials. The effect of antifoulant
materials for crude oil treatment is described below.
EXAMPLE II
Thermal Fouling Testing of Untreated Crude Oil
[0044] The thermal fouling characteristics of untreated crude oil
is determined using the TFTM described above. The thermal fouling
test results show that the crude oil used in connection with these
tests is a relatively high fouling crude oil. Test conditions and
test fouling results are presented below.
1 Exchanger heater metal temperature 700.degree. F. Liquid outlet
temperature 510.degree. F. Unit operating pressure 800 psig
Exchanger heater metal type C/S 1018 Oil flow 3.0 cc/min Test time
180 minutes Measured fouling 70.degree. F.
EXAMPLE III
Thermal Fouling Testing of Crude Oil Containing Conventional
PIBSA-PAM Antifouling Agent
[0045] A crude oil identical to the crude oil tested in Example I
was blended with 100 ppm (wt) of the acquired PIBSA-PAM that was
made with conventional PIB. This conventional commercially
available PIBSA-PAM had the following characteristics:
2 Average molecular weight (M.sub.N) 1300 Carbon content 82.87 wt %
Hydrogen content 12.89 wt % Oxygen content 0.90 wt % Nitrogen
content 4.8 wt % Carbon/Hydrogen atomic ratio 0.53 Total base
number 114 mg/gm
[0046] The TFTM was used to determine the thermal fouling of the
treated crude oil using exactly the same operating conditions as
used in Example II. Test results show that the crude oil treated
with conventional PIBSA-PAM has reduced fouling characteristics as
compared with the untreated crude oil. Test operating conditions
and results are presented below.
3 Exchanger heater metal temperature 700.degree. F. Liquid outlet
temperature 514.degree. F. Unit operating pressure 800 psig
Exchanger heater metal type C/S 1018 Oil flow 3.0 cc/min Test time
180 minutes Measured fouling 46.degree. F.
EXAMPLE IV
Thermal Fouling Testing of Crude Oil Containing a PIBSA-PAM
Antifouling Agent Prepared from Improved PIBSA-PAM
[0047] A crude oil identical to the crude oil tested in Example I
was blended with 100 ppm (wt) of the PIBSA-PAM made in accordance
with Example I. This improved PIBSA-PAM had the following
characteristics:
4 Average molecular weight (M.sub.N) 1300 Nitrogen content 8.9 wt %
Total base number 132 mg/gm
[0048] The TFTM was used to determine the thermal fouling of the
treated crude oil using exactly the same operating conditions as
used in Examples II and III. The test results set forth below show
that the crude oil treated with the PIBSA-PAM of the invention that
is made from a PIB having a significant content of vinylidene
double bonds, has reduced fouling characteristics as compared with
either the untreated crude oil or the crude oil treated with
conventional PIBSA-PAM. Test operating conditions and results are
presented below.
5 Exchanger heater metal temperature 700.degree. F. Liquid outlet
temperature 507.degree. F. Unit operating pressure 800 psig
Exchanger heater metal type C/S 1018 Oil flow 3.0 cc/min Test time
180 minutes Measured fouling 30.degree. F.
* * * * *