U.S. patent application number 11/399162 was filed with the patent office on 2006-11-09 for process for reducing the total acid number (tan) of a liquid hydrocarbonaceous feedstock.
Invention is credited to Carolus Matthias Anna Maria Mesters.
Application Number | 20060249430 11/399162 |
Document ID | / |
Family ID | 34938139 |
Filed Date | 2006-11-09 |
United States Patent
Application |
20060249430 |
Kind Code |
A1 |
Mesters; Carolus Matthias Anna
Maria |
November 9, 2006 |
Process for reducing the total acid number (TAN) of a liquid
hydrocarbonaceous feedstock
Abstract
A process for reducing the total acid number (TAN) of a liquid
hydrocarbonaceous feedstock, wherein the feedstock is contacted, in
the presence of a hydrogen-containing gas and at a temperature in
the range of from 200 to 400.degree. C. and at elevated pressure,
with a catalyst comprising an oxide of a metal of Column 3 or 4 of
the Periodic Table of Elements or of a lanthanide, which catalyst
is essentially free of Column 5 to 10 metals or compounds thereof,
to obtain a liquid hydrocarbonaceous product with a reduced total
acid number.
Inventors: |
Mesters; Carolus Matthias Anna
Maria; (Amsterdam, NL) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
34938139 |
Appl. No.: |
11/399162 |
Filed: |
April 6, 2006 |
Current U.S.
Class: |
208/263 |
Current CPC
Class: |
C10G 49/005 20130101;
C10G 45/00 20130101; C10G 75/00 20130101 |
Class at
Publication: |
208/263 |
International
Class: |
C10G 17/00 20060101
C10G017/00; C10G 45/00 20060101 C10G045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 6, 2005 |
EP |
05075793.9 |
Claims
1. A process for reducing the total acid number (TAN) of a liquid
hydrocarbonaceous feedstock, wherein the feedstock is contacted, in
the presence of a hydrogen-containing gas and at a temperature in
the range of from 200 to 400.degree. C. and at elevated pressure,
with a catalyst comprising an oxide of a metal of Column 3 or 4 of
the Periodic Table of Elements or of a lanthanide, which catalyst
is essentially free of Column 5 to 10 metals or compounds thereof,
to obtain a liquid hydrocarbonaceous product with a reduced total
acid number.
2. A process according to claim 1, wherein the oxide is an oxide of
a Column 4 metal or of a lanthanide.
3. A process according to claim 2, wherein the oxide is titanium
oxide or zirconium oxide.
4. A process according to claim 3, wherein the catalyst essentially
consists of titanium oxide and/or zirconium oxide.
5. A process according to claim 1, wherein the pressure is in the
range of from 2 to200 bar g.
6. A process according to claim 1, wherein the temperature is in
the range of from 250 to 390.degree. C.
7. A process according to claim 1, wherein the hydrogen-containing
gas is synthesis gas or hydrogen.
8. A process according to claim 1, wherein the feedstock has a TAN
of at least 0.2 mg KOH/g feedstock.
9. A process according to claim 1, wherein the feedstock has a TAN
of at least 0.5 mg KOH/g feedstock.
10. A process according to claim 1, wherein the feedstock has a TAN
of at least 1 mg KOH/g feedstock.
11. A process according to claim 1, wherein the liquid
hydrocarbonaceous product has a TAN of at most 0.2 mg KOH/g
feedstock.
12. A process according to claim 1, wherein the liquid
hydrocarbonaceous product has a TAN of at most 0.1 mg KOH/g
feedstock.
13. A process according to claim 1, wherein the liquid
hydrocarbonaceous product has a TAN of at most 0.05 mg KOH/g
feedstock.
14. A process according to claim 1, wherein the liquid
hydrocarbonaceous product with a reduced total acid number has a
TAN of at most 50% of the TAN of the crude oil product.
15. A process according to claim 1, wherein the liquid
hydrocarbonaceous product with a reduced total acid number has a
TAN of at most 30% of the TAN of the crude oil product.
16. A process according to claim 1, wherein the liquid
hydrocarbonaceous feedstock is crude oil.
Description
FIELD OF THE INVENTION
[0001] The present invention provides a process for reducing the
total acid number (TAN) of a liquid hydrocarbonaceous feedstock, in
particular crude oil.
BACKGROUND OF THE INVENTION
[0002] Crude oil and other liquid hydrocarbonaceous streams with a
high amount of acids are difficult to refine. Especially in the
distillation unit of a crude oil refinery, a high amount of acids
leads to corrosion problems. It is known that acids are removed by
hydrotreating, i.e. the same process wherein other heteroatoms like
sulphur and nitrogen are removed from liquid hydrocarbonaceous
feedstocks. Hydrotreating, however, is a process that is carried
out downstream of the distillation unit in a refinery.
[0003] In order to avoid corrosion problems resulting from the acid
content of the crude oil, different crude oil streams are typically
blended to obtain a crude oil feedstock with an acceptable amount
of acids.
[0004] The acid content of a crude oil or of other
hydrocarbonaceous liquids is generally expressed as the total acid
number (TAN) of such liquid. The TAN represents milligrams KOH per
gram liquid needed to neutralise the acid according to a procedure
described in ASTM D664.
[0005] There is a need in the art for a process that is able to
reduce the TAN of liquid hydrocarbonaceous streams such as crude
oil that are used as feedstock in refineries, with minimum
conversion of sulphur- and nitrogen-containing compounds and
unsaturated hydrocarbons. By such process, an acceptable refinery
feedstock would be obtained with minimal hydrogen consumption.
SUMMARY OF THE INVENTION
[0006] The present invention provides a process for reducing the
total acid number (TAN) of a liquid hydrocarbonaceous feedstock,
wherein the feedstock is contacted, in the presence of a
hydrogen-containing gas and at a temperature in the range of from
200 to 400.degree. C. and at elevated pressure, with a catalyst
comprising an oxide of a metal of Column 3 or 4 of the Periodic
Table of Elements or of a lanthanide, which catalyst is essentially
free of Column 5 to 10 metals or compounds thereof, to obtain a
liquid hydrocarbonaceous product with a reduced total acid
number.
[0007] An advantage of the process according to the invention is
that the total acid number of the feedstock is reduced by
hydrogenation whilst other hydrogenation reactions such as
hydrodesulphurisation, hydrodenitrogenation and saturation of
unsaturated hydrocarbons are minimised.
DETAILED DESCRIPTION OF THE INVENTION
[0008] It has been found that catalysts that are essentially free
of the hydrogenating components that are typically used for
hydroconversion reactions such as hydrodesulphurisation,
hydrodenitrogenation, and hydrocracking, i.e. compounds of metals
of any one of Columns 5 to 10 of the Periodic Table of Elements,
can be used for the selective hydrogenation of acids in liquid
hydrocarbonaceous streams, in particular crude oil.
[0009] In the process according to the invention, a liquid
hydrocarbonaceous feedstock is contacted, in the presence of a
hydrogen-containing gas at a temperature in the range of from 200
to 400.degree. C. and at elevated pressure, with a catalyst
comprising an oxide of a Column 3 or 4 metal or of a lanthanide,
which catalyst is essentially free of Column 5 to 10 metals or
compounds thereof.
[0010] The feedstock may be any liquid hydrocarbonaceous stream
comprising carboxylic, i.e. organic, acids. The process is
particularly suitable for feedstocks comprising naphthenic acids.
Preferably, the feedstock is a crude oil, a distillate stream such
as naphtha or gasoil, a residue fraction of an atmospheric crude
oil distillation or a hydrocarbonaceous distillate product not
meeting TAN product specifications, such as for example heating
oil. The process according to the invention is particularly
suitable for the reduction of the total acid number of crude
oil.
[0011] The hydrogen-containing gas is preferably hydrogen or
synthesis gas. The use of synthesis gas as hydrogen-containing gas
is particularly advantageous in a situation wherein no hydrogen gas
is available, for example at remote places such as off-shore oil
platforms.
[0012] The temperature and pressure at which the feedstock is
contacted with the catalyst is such that hydrogenation of
carboxylic acids takes place, i.e. at least 200.degree. C. The
temperature is below the temperature at which thermal decomposition
of carboxylic acids occurs, i.e. below 400.degree. C. Preferably,
the temperature is in the range of from 250 to 390.degree. C., more
preferably of from 300 to 380.degree. C.
[0013] The process is performed at elevated pressure, i.e. above
atmospheric pressure. Preferably, the pressure is in the range of
from 2 to 200 bar g, more preferably of from 10 to 150 bar g, even
more preferably of from 25 to 120 bar g.
[0014] The catalyst comprises an oxide of a metal of Column 3 or 4
of the Periodic Table of Elements (latest IUPAC notation) or of a
lanthanide. The oxide may also be a mixed oxide of two or more of
such metals. The catalyst may also comprise a mixture of two or
more of such oxides. The catalyst is essentially free of metals of
Columns 5 to 10 of the Periodic Table of Elements (latest IUPAC
notation) or of compounds thereof. Reference herein to a catalyst
essentially free of certain compounds is to a catalyst that is free
of such compounds except for minimal amounts, typically in the ppm
range or lower, that may be present as unintentional contaminants
or as left-overs from a mineral ore refining process for obtaining
the oxide of the Column 3 or 4 metal or lanthanide.
[0015] Preferably, the catalyst comprises an oxide of a Column 4
metal or of a lanthanide. Preferred Group 4 metal oxides are
titanium oxide and zirconium oxide, a preferred oxide of a
lanthanide is ceria. More preferably, the catalyst consists of
titanium oxide and/or zirconium oxide, even more preferably of
zirconium oxide.
[0016] The catalyst may be prepared by any preparation method known
in the art. Preferably, the catalyst is prepared such that its
specific surface area is at least 10 m.sup.2/g, more preferably at
least 30 m.sup.2/g.
[0017] The feedstock for the process according to the invention
preferably has a total acid number of at least 0.2 mg KOH/g
feedstock, preferably at least 0.5 mg KOH/g feedstock, more
preferably at least 1.0 mg KOH/g feedstock. Reference herein to the
total acid number is to the amount of KOH (in mg) per gram
feedstock as determined by ASTM D664.
[0018] The liquid hydrocarbonaceous product has preferably a TAN of
at most 0.2 mg KOH/g feedstock, more preferably at most 0.1 mg
KOH/g feedstock, even more preferably at most 0.05 mg KOH/g
feedstock.
[0019] The TAN is preferably reduced to such extent that the liquid
hydrocarbonaceous product with a reduced total acid number has at
most 50% of the TAN of the feedstock, more preferably at most
30%.
EXAMPLE
Hydrogenation Process
[0020] In a microflow reactor, crude oil was contacted with a solid
inert material (0.1 mm silicon carbide particles) or with one of
the catalysts described below (catalyst particles diluted with
silicon carbide particles: 1/1 v/v) in the presence of a
hydrogen-containing gas or nitrogen for at least 100 hours. Two
different crude oils were used. For experiments 1 to 8 and 13 to
16, a West-African crude oil was used (crude 1); for experiments 9
to 12, a crude oil from the Middle-East was used (crude 2). The
specifications of both crude oils are shown in table 1. The exact
conditions for each experiment are given in table 2.
[0021] The total acid number (TAN) of the liquid effluent of each
of the experiments was determined according to ASTM D664. The
hydrogen sulphide concentration in the vapour phase effluent was
determined by gas chromatography. TAN of the liquid effluent and
the hydrogen sulphide concentration in the vapour phase effluent
are also shown in table 2.
[0022] Experiments 3, 4, 6, 7, 9, 10, 12 and 14 to 16 are
experiments according to the invention. Experiments 1, 2, 5, 8, 11,
and 13 are comparison experiments. TABLE-US-00001 TABLE 1 Crude oil
specification Property Crude 1 Crude 2 Sulphur content (% wt) 0.41
4.1 Ni content (mg/kg) 32 36 V content (mg/kg) 4 138 TAN (mg KOH/g
oil) 2.7 1.3 Density (g/ml) 0.93 0.91 Sediment (mg/kg) 10 1250
Water content (% wt) 0.08 0.27 C.sub.5+ asphalthenes (mg/kg) 0.26
9.7
Catalysts
[0023] The following catalysts were used in the hydrogenation
experiments.
Titania Catalyst 1
[0024] A titania catalyst further referred to as titania 1 was
prepared as follows. An amount of 3192 grams of titania powder
(P25, ex. Degussa; loss on ignition: 4.4 wt % at 540.degree. C.)
was mixed with 100 grams oxalic acid dihydrate in a mix-muller
kneader (Simpson). After 4 minutes of mix-mulling, 981 grams of
de-ionised water and 100 grams of polyethylene glycol were added
and mix-mulling was continued for another 12 minutes. Then, 100
grams of methyl cellulose were added and mix-mulling was continued
for another 20 minutes. The thus-formed mixture was shaped by
extrusion through a 1.7 mm diameter trilobe-shaped die-plate. The
trilobes were dried for 2 hours at 120.degree. C. and calcined for
2 hours at 500.degree. C.
[0025] The resulting titania trilobes have a surface area of 52
m.sup.2/g as measured by nitrogen adsorption (BET method) and a
pore volume of 0.31 ml/g as measured by mercury intrusion.
Titania Catalyst 2
[0026] Titania particles commercially available as X096 (ex. CRI
Catalyst Company) were used as titania catalyst (further referred
to as titania 2). These titania particles have a surface area of
120 m.sup.2/g as measured by nitrogen adsorption (BET method) and a
pore volume of 0.32 ml/g as measured by mercury intrusion.
Zirconia Catalyst
[0027] A zirconia catalyst was prepared as follows. An amount of
264 grams of zirconia powder (RC100, ex. Daiichi; loss on ignition:
5.3 wt % at 540.degree. C.) was mixed with 90 grams of a solution
of 5 wt % polyvinyl alcohol in de-ionised water in a kneader
(Wemer&Pfeider Sigma kneader type LUK 0.75). After 7 minutes of
kneading, 2.5 grams of a cationic poly acryl amide (Superfloc, ex.
Cytec) were added and after 20 minutes of kneading 8 grams of
de-ionised water were added. The mixture was kneaded for another 22
minutes. The thus-formed mixture was shaped by extrusion into 1.7
mm diameter trilobes. The extrudates were dried for 2 hours at
120.degree. C. and calcined for 2 hours at 550.degree. C.
[0028] The resulting zirconia trilobes have a surface area of 54
m.sup.2/g as measured by nitrogen adsorption (BET method) and a
pore volume of 0.35 ml/g as measured by mercury intrusion.
NiMo on Alumina
[0029] A conventional hydrodesulphurisation catalyst comprising Ni
and Mo on alumina, which is commercially available as CRITERION
RM-5030 (ex. Criterion Catalyst Company), was used. TABLE-US-00002
TABLE 2 Process conditions; TAN in liquid effluent and H.sub.2S in
vapour effluent. Experiment p T H.sub.2S in vapour No. crude oil
catalyst gas (bar g) (.degree. C.) WHV.sup.a gas rate.sup.b
TAN.sup.c (ppmv) 1 1 none (SiC) H.sub.2 10 300 -- 720 2.3
n.d..sup.d 2 1 none (SiC) H.sub.2 100 300 -- 760 2.3 n.d..sup.d 3 1
titania 1 H.sub.2 10 300 1.2 260 0.7 n.d..sup.d 4 1 titania 1
H.sub.2 100 300 1.1 270 0.3 n.d..sup.d 5 1 titania 1 N.sub.2 100
300 1.1 370 2.5 n.d..sup.d 6 1 titania 2 H.sub.2 10 350 3 290
<0.05 n.d..sup.d 7 1 titania 2 syngas.sup.f 10 350 3 280 0.3
n.d..sup.d 8 1 NiMo/ H.sub.2 10 350 3.7 280 0.05 n.d..sup.e alumina
9 2 titania 2 H.sub.2 10 350 2 250 0.1 n.d..sup.d 10 2 titania 2
syngas.sup.f 10 350 2 300 0.2 n.d..sup.d 11 2 NiMo/ H.sub.2 40 350
1.7 250 <0.05 8800 alumina 12 2 titania 2 H.sub.2 40 350 2 250
<0.05 148 13 1 NiMo/ H.sub.2 10 350 1.7 300 0.13 542 alumina 14
1 titania 2 H.sub.2 40 350 3 250 0.05 35 15 1 zirconia H.sub.2 10
335 1.2 330 0.07 <10 16 1 titania 1 H.sub.2 10 335 1.3 356 0.24
<10 .sup.aWHV: weight hourly velocity, i.e. kg oil/kg
catalyst/hour. In experiments 1 and 2, no catalyst was present and
no comparable WHV could be defined (the weight hourly velocity of
the oil was 1.1 kg/kg SiC/h in experiments 1 and 2). .sup.bgas rate
in normal litres gas per kg oil. .sup.cTAN in mg KOH/g oil.
.sup.dnot detectable; liquid effluent did not have a smell of
hydrogen sulphide. .sup.enot detectable; liquid effluent had a
smell of hydrogen sulphide. .sup.fsyngas composition: 33.2 vol %
hydrogen; 20.7 vol % CO; balance nitrogen.
* * * * *