U.S. patent application number 11/722178 was filed with the patent office on 2008-10-16 for synthetically derived illuminating and heating paraffin oil.
This patent application is currently assigned to The Petroleum Oil and Gas Corporation of South Africa (PTY) Ltd. Invention is credited to Carl Dunlop, Cyril David Knottenbelt, Maxwell Thomas, Kholekile Zono.
Application Number | 20080250704 11/722178 |
Document ID | / |
Family ID | 36084795 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080250704 |
Kind Code |
A1 |
Knottenbelt; Cyril David ;
et al. |
October 16, 2008 |
Synthetically Derived Illuminating and Heating Paraffin Oil
Abstract
The invention provides synthetically derived distillate kerosene
produced by catalytic conversion of Fisher-Tropsch derived light
olefins to distillates (COD) and hydrotreating thereof. The
kerosene boils in the range of about 170 to 250.degree. C. and
includes less than 10% n-paraffins, more than 75% iso-paraffins and
less than 1% aromatics.
Inventors: |
Knottenbelt; Cyril David;
(Mossel Bay, ZA) ; Dunlop; Carl; (Cape Town,
ZA) ; Zono; Kholekile; (Mossel Bay, ZA) ;
Thomas; Maxwell; (Mossel Bay, ZA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
2040 MAIN STREET, FOURTEENTH FLOOR
IRVINE
CA
92614
US
|
Assignee: |
The Petroleum Oil and Gas
Corporation of South Africa (PTY) Ltd
Mossel Bay
ZA
|
Family ID: |
36084795 |
Appl. No.: |
11/722178 |
Filed: |
December 20, 2005 |
PCT Filed: |
December 20, 2005 |
PCT NO: |
PCT/ZA05/00186 |
371 Date: |
January 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60638433 |
Dec 22, 2004 |
|
|
|
Current U.S.
Class: |
44/389 |
Current CPC
Class: |
C10L 1/04 20130101 |
Class at
Publication: |
44/389 |
International
Class: |
C10L 1/04 20060101
C10L001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 2004 |
ZA |
2004/10360 |
Feb 16, 2005 |
ZA |
2005/1372 |
Feb 16, 2005 |
ZA |
2005/1373 |
Claims
1-27. (canceled)
28. A synthetically derived distillate kerosene produced by
catalytic conversion of Fisher-Tropsch derived light olefins to
distillates and hydrotreating thereof the kerosene having a boiling
range of from about 180 to 215.degree. C., and the kerosene
comprising: less than 10% n-paraffins; more than 75% iso-paraffins;
less than 1% aromatics; and about 10% naphthenes.
29. A synthetically derived distillate kerosene produced by
catalytic conversion of Fisher-Tropsch derived light olefins to
distillates and hydrotreating thereof, the kerosene having a
boiling range of from about 180 to 215.degree. C., the kerosene
comprising: less than 10% n-paraffins; more than 60% iso-paraffins;
less than 10% aromatics as mono aromatics only; and about 10%
naphthenes.
30. The synthetically derived distillate kerosene of claim 28,
having a flash point as measured by ASTM D93 of from 60.degree. C.
to 80.degree. C., a kinematic viscosity at 40.degree. C. as
measured by ASTM D445 below about 1.5 cSt, a char value as measured
by IP10 below 2 mg/Kg, a total sulfur content of below 0.3 ppm(m/m)
as measured by ASTM 3120, an olefins content reflected by a bromine
number of less than 1 mg/100 g as measured by IP 129, and a
peroxide number of less than 1 mg/100 g as measured by ASTM
D3703.
31. The synthetically derived distillate kerosene of claim 29,
having a flash point as measured by ASTM D93 of from 60.degree. C.
to 80.degree. C., a kinematic viscosity at 40.degree. C. as
measured by ASTM D445 below about 1.5 cSt, a char value as measured
by IP10 below 2 mg/Kg, a total sulfur content of below 0.3 ppm(m/m)
as measured by ASTM 3120, an olefins content reflected by a bromine
number of less than 1 mg/100 g as measured by IP 129, and a
peroxide number of less than 1 mg/100 g as measured by ASTM
D3703.
32. The synthetically derived distillate kerosene of claim 30,
which further comprising at least one additive selected from the
group consisting of perfume and insect repellent.
33. The synthetically derived distillate kerosene of claim 31,
which further comprising at least one additive selected from the
group consisting of perfume and insect repellent.
34. A process for the production of kerosene, comprising the steps
of: catalytic conversion of Fisher-Tropsch derived light olefins to
distillates over a shape selective zeolite catalyst, whereby a COD
product is obtained; and hydrotreating the COD product; and
collecting a hydrotreated fraction boiling between about 170 to
250.degree. C.
35. The process of claim 34, wherein the hydrotreating step
comprises distillate hydrotreating the COD product to produce an
intermediate COD product, followed by deep hydrotreating the
intermediate COD product to remove practically all aromatics.
36. The process of claim 35, wherein a hydrotreated fraction
boiling at from about 170 to 250.degree. C. is collected during the
distillate hydrotreating step before the deep hydrotreating
step.
37. The process of claim 34, wherein the hydrotreating step
comprises a one step deep hydrotreating step of the COD product,
and is followed by the step of collecting the hydrotreated fraction
boiling between about 170 to 250.degree. C.
38. The process of claim 37, wherein the hydrotreating catalyst is
a high nickel content catalyst.
39. The process of claim 38, wherein the catalyst is bimetallic and
comprises a noble metal.
40. The process of claim 39, wherein the noble metal is
platinum.
41. The process of claim 40, wherein the catalyst is selected from
selected from the group consisting of nickel supported on alumina
and platinum supported on alumina.
42. The process of claim 34, wherein a hydrogenation reaction
pressure for the hydrotreating step is from 5000 kPa to about 8000
kPa, wherein a reaction temperatures is from 200.degree. C. to
260.degree. C., and wherein a liquid hourly space velocity for the
hydrotreating step is from 0.3 to 2.
43. The process of claim 34, wherein the COD product is
hydrogenated over a catalyst selected from the group consisting of
a nickel-molybdenum catalyst and a cobalt-molybdenum catalyst.
44. The process of claim 43, wherein the reaction temperature is
from about 240.degree. C. to below 350.degree. C., wherein a
reaction pressure is from 5000 to 8000 kPa, wherein a hydrogen to
hydrocarbon ratio is maintained at about 400 nm.sup.3/hr, and
wherein a liquid hourly space velocity for the hydrotreating step
is from 0.3 and 1.
45. The process of claim 34, wherein a portion of the hydrotreated
product is recycled to quench a hydrogenation reaction in the
hydrotreating step.
46. The process of claim 34, wherein the hydrotreatment catalyst
bed comprises multiple zones with increased grades.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates to synthetically derived Illuminating
and heating paraffin oil, or kerosene, for household use and a
process for its production.
BACKGROUND TO THE INVENTION
[0002] Household illuminating and heating kerosene has been known
and used for since the late 1850's. Kerosene has a wide boiling
range of 150-300.degree. C. However, narrow boiling ranges are
produced for improved control of final product combustion
properties. Kerosene burning household appliances are manufactured
with the specific characteristics of kerosene in mind. Known
kerosene's are derived from crude oil by fractional distillation.
Crude oil derived kerosene normally appears light yellow, contains
sulphur, and aromatics which give the kerosene a distinct and
negatively perceived odour.
[0003] Prior art processes for manufacturing illuminating and
heating kerosene includes drying low sulphur paraffinic kerosene's
to remove water and removing mercaptan by means of caustic washing
or additional treatment to convert mercaptans to odorless
disulphides. Highly paraffininic feed stocks may require additives
to improve their performance in cold climates, these could include
pour point depressants or wax crystal modifiers.
[0004] In the case of naphthenic or high sulphur crudes, processes
for manufacturing illuminating and heating kerosene includes
hydrotreating followed by acid treatment followed by water washing,
or solvent extraction combined with caustic washing and clay
treatment to remove undesirable aromatics and sulphur compounds. In
the case of cracked feedstocks derived from heavy fuel oils, severe
hydrotreating is required to remove olefins and other unstable
compounds.
[0005] It is well known that aromatics are carcinogenic. When crude
derived kerosene is burned it produces particulate matter, which
leaves a residue. Residue needs to be cleaned from any household
appliances. Crude derived kerosene also produces smoke and a
distinct smell when it is burned. Due to the toxicity, appearance
and odour of crude derived kerosene, it has not been widely
accepted in modern households despite its relatively low cost.
Recently however, synthetically derived kerosene appeared on the
market. Synthetically derived kerosene is normally colourless and
has preferred burning characteristics. Although it is more widely
acceptable for household use than crude derived kerosene middle
distillates, it contains aromatics. It is well known that aromatics
are carcinogenic and gives the kerosene a distinct and still
negatively perceived odour. An example of such known synthetically
derived kerosene containing high levels of aromatics is a kerosene
distillate cut from the High Temperature Fisher-Tropsch process.
Household illuminating and heating kerosene contains three main
types of paraffinic, naphthenic, and aromatic hydrocarbons. The
quality of kerosene as a burning or heating oil is related to its
burning characteristics and is dependent on such factors as its
composition, volatility, viscosity, calorific value, sulphur
content, and freedom from corrosive substances or contaminants.
[0006] It is an object of this invention to provide synthetically
derived kerosene, which is colourless, odourless, non toxic, has
excellent cold flow properties over a relatively wide boiling range
while not giving away good flash point characteristics and having
excellent burn characteristics.
[0007] The applicant is aware that, while paraffin's have excellent
burning properties, aromatics, in particular multiple ring
polynuclear aromatics, tend to burn less elegantly and contribute
to smoke and carbon formation. Naphthenes have intermediate
properties however, their combustion characteristics tend to be
closer to paraffins than aromatic hydrocarbon types. In order to
limit smoke formation, paraffinic feedstocks are selected for
indoor illumination and heating purposes, and aromatic feedstocks
especially those with multiple ring aromatics as well as cracked
feedstocks containing olefins are avoided.
[0008] The applicant has found that the burn characteristics of
kerosenes improve with in the presence of trace amounts of
mono-aromatic species (single ring compounds only). The applicant
has further found that too high levels of aromatics and naphtenes
burn with a reddish and sometimes smoky flame. However, it is an
object of this invention to provide a kerosene with negligible
quantities of aromatics and comprising mainly of iso-paraffins.
[0009] In this specification, references to percentage proportions
refer to mass percentage proportions. In this specification,
general reference to burn characteristics, refers to burning
characteristics in wick-fed yellow flame burners, which are not of
the primus type however these fuels perform well in aspirated and
high pressure atomising gun burners as well.
DESCRIPTION OF THE INVENTION
[0010] According to a first aspect of the invention there is
provided a synthetically derived distillate kerosene produced by
catalytic conversion of Fisher-Tropsch derived light olefins to
distillates (COD) and hydrotreating thereof, the kerosene boiling
in the range of about 170 to 250.degree. C., and including:
[0011] less than 10% n-paraffins;
[0012] more than 75% iso-paraffins; and
[0013] less than 1% aromatics.
[0014] The kerosene may include about 10% naphtenes.
[0015] Alternatively, the kerosene may include: [0016] less than
10% n-paraffins; [0017] more than 60% iso-paraffins; and [0018]
less than 10% aromatics as mono aromatics only
[0019] The kerosene may then also include about 10% naphtenes.
[0020] The applicant has found that naphtenes (cycloparaffins) also
influence the burning characteristics of the kerosene. The
applicant has found that about 10% of naphtenes in combination with
the abovementioned ranges of n-paraffins, iso-paraffins and
aromatics produces kerosene with good burning characteristics.
[0021] Preferably the boiling range may be between 180 to
215.degree. C.
[0022] The flash point of the kerosene as measured by ASTM D93 may
be higher than 60.degree. C. for safety reasons but preferably
lower than 80.degree. C. for ease of ignition.
[0023] The kinematic viscosity at 40.degree. C. of the kerosene as
measured by ASTM D445 may be below about 1.5 cSt. The kinematic
viscosity plays a role in capillary movement of the kerosene
through the wick. It will be appreciated that kerosene with a low
viscosity will move more readily through a wick than kerosene with
a higher viscosity. It will be appreciated that poor viscosity can
lead to inadequate vaporisation at the wick tip and lead to
carbonisation and subsequent wick fowling.
[0024] The char value as measured by IP10 may be below 3 mg/Kg,
preferably 2 or lower. Formation of char is normally formed by
impurities including poly aromatic hydrocarbons and/or high boiling
residues.
[0025] The total sulphur content of the kerosene may be below 0.3
ppm(m/m) as measured by ASTM 3120. Sulphur in kerosene can cause
deposits of a lamp chimney, also known as "bloom". The presence of
sulphur containing mercaptans leads to objectionable odours and
leads to corrosion of household appliances.
[0026] The olefins content may be respectively reflected by a
bromine number of less than 1 mg/100 g as measured by IP 129 and a
peroxide number of less than 1 mg/100 g as measured by ASTM D3703.
Catalytically cracked material that is high in olefin content tends
to be less chemically stable and for sediment on prolonged storage.
These olefins may also react with sunlight causing the product to
oxidise and discolour.
[0027] The kerosene may further include perfumes and/or insect
repellent. It will be appreciated that the kerosene function as a
carrier for the perfume and/or insect repellent, which vaporise
when the kerosene is burnt.
[0028] According to a second aspect of the invention, there is
provided a process for the production of kerosene as described
above, which process includes the steps of:
[0029] catalytic conversion of Fisher-Tropsch derived light olefins
to distillates (COD) over a shape selective catalyst; and
[0030] hydrotreating the COD product; and
[0031] collecting a hydrotreated fraction boiling between about 170
to 250.degree. C.
[0032] The Fisher-Tropsch derived olefins are converted to
distillates over a shape selective zeolite catalyst. The conversion
includes oligomerising and isomerising of the Fisher-Tropsch
derived olefins to produce an intermediate olefinic COD
product.
[0033] The hydrotreating step may include two steps, first
distillate hydrotreating of the COD product followed by an optional
second deep hydrotreating step to remove practically all aromatics.
The hydrotreated fraction boiling between about 170 to 250.degree.
C. may be collected during the distillate hydrotreating step before
the deep hydrotreating step.
[0034] Alternatively, the hydrotreating step may comprise a one
step deep hydrotreating step of the COD product followed by
collecting of the hydrotreated fraction boiling between about 170
to 240.degree. C.
[0035] It will be appreciated that a one step reaction requires a
lower capital and running costs, while the two step reaction
enables better heat management.
[0036] The one step deep hydrotreating process may include
hydrogenation over a Group 10 metal catalyst.
[0037] The Group 10 metal catalyst may include a high nickel
content.
[0038] Alternatively, the Group 10 catalyst may include a noble
metal such as supported platinum catalysts. These catalysts may
also be bimetallic.
[0039] The catalyst may be Nickel supported on alumina or platinum
supported on allumina. (Sud Chemie G134 or Axens LD 402).
[0040] The one step deep hydrotreating step may include
hydrogenation over a high nickel content hydrotreating catalyst or
hydrotreating with a nobel metal catalyst. Reactor pressures for
such reactions would typically range from 5000 kPa to about 8000
kPa but not excluding higher pressures. Reaction temperatures vary
from about 200.degree. C. to 260.degree. C. while the LHSV range
from 0.3 to 2 depending on the feed.
[0041] In the two step hydrotreating step, the intermediate
olefinic product is hydrogenated over a nickel-molybdenum catalyst
(Axens HR348 for such Sulphur and Nitrogen free feeds) or over
cobalt-molybdenum catalysts. The support may be Al.sub.2O.sub.3 or
SiO.sub.2/Al.sub.2O.sub.3. The reaction temperature ranges from
about 240 to below 350.degree. C. at pressures of between 5000 to
8000 kPa. The hydrogen to hydrocarbon ratio is maintained at about
400 nm.sup.3/hr at LHSV of between 0.3 and 1.
[0042] The kerosene has a low aromatic content comprising of only
alkylated mono-aromatic species and contains no poly aromatic
hydrocarbons. In order to remove these small quantities of
mono-aromatics, the second, deep, hydrotreating step may
follow.
[0043] The support for the metal may be neutral. The applicant is
aware that an acidic support causes unwanted cracking during
hydrogenation.
[0044] The olefin content measured as Bromine Number determines the
reactivity of a particular feed, highly reactive feeds may require
a portion of the hydrogenated product to be recycled to quench the
hydrogenation reaction of the hydroteating step. The LHSV may also
be altered to below 0.5 to control excessive exothermic
reactions.
[0045] The hydrotreatment catalyst may be loaded into the reactor
bed in an increased graded approach to limit an excessive
exothermic reaction developing at the top of the reactor. The
catalyst bed may have multiple zones with increased grades.
Typically, a 4-zone graded catalyst bed. The concentration of the
active catalyst in each of the 4 zones may be diluted with an inert
ceramic in the following typical ratios of catalyst to ceramics,
0.2; 0.5; 170.0 and 650.
[0046] The catalytic conversion at pressures of more than 50 barg
and/or a reactor temperature maintained below 280.degree. C.
produces a product stream with low aromatics and it will be
appreciated that the relative low aromatics from the COD step
allows moderate hydrogenation reactor conditions, limiting unwanted
side reactions.
[0047] These synthetically derived middle distillates have been
found to work particularly well as illuminating and heating oils in
the household environment. This product provides excellent
performance in wick fed appliances as well as in appliances where
the fuel is atomised. Not only do these appliances give good
performance but give excellent environmental and hygiene
performance providing low smoke and chemical emissions free of any
undesired chemical compounds. This product basis its excellent
combustion characteristics, good environmental performance, the
unique and environmentally responsible manner in which it is
produced is highly recommend for indoor use. These fuels work
particularly well in modern heaters that operate either with a wick
or with heaters where the fuel is atomised prior to burning.
[0048] The invention is now described by means of non limiting
examples:
EXAMPLE 1
[0049] A synthetically derived distillate (kerosene) produced by
catalytic conversion of Fisher-Tropsch derived light olefins to
distillates (COD) and hydrotreating thereof. The kerosene boils in
the range of 185 to 220.degree. C., and includes 7% n-paraffins,
87% iso-paraffins, 5.5% naphtenes and 0.05% aromatics.
[0050] The flash point of the kerosene as measured by ASTM D93 is
at least 64-.degree. C.
[0051] The kinematic viscosity at 40.degree. C. of the kerosene as
measured by ASTM D445 is at least 1.3 cSt, however more typically
1.4 cSt.
[0052] The char value as measured by IP10 is less than 2 mg/Kg,
more typically 1 or lower. Formation of char is normally formed by
impurities including poly aromatic hydrocarbons and/or high boiling
residues.
[0053] The smoke point as measured by IP 57 has been found to be 45
mm. Smoke point reflects the maximum wick height that the wick of a
yellow-flame type lamp can be turned up to prior to smoke
formation, a high smoke point of as close to 45 mm is
desirable.
[0054] The total sulphur content of the kerosene is below 0.3
ppm(m/m) as measured by ASTM 3120.
EXAMPLE 2
[0055] A synthetically derived distillate (kerosene) produced by
catalytic conversion of Fisher-Tropsch derived light olefins to
distillates (COD) and the hydrotreating thereof. The kerosene boils
in the range of 180 to 220.degree. C., and includes less than 7%
n-paraffins; 75% iso-paraffins; 10% naphtenes and 8% aromatics as
mono aromatics only.
[0056] The flash point of the kerosene as measured by ASTM D93 is
at least 64.degree. C.
[0057] The kinematic viscosity at 40.degree. C. of the kerosene as
measured by ASTM D445 is 64.degree. C. cSt.
[0058] The char value as measured by IP10 is 2 mg/Kg, more
typically 1 or lower. Formation of char is normally formed by
impurities including poly aromatic hydrocarbons and/or high boiling
residues.
[0059] The smoke point as measured by IP 57 has been found to be 44
mm. Smoke point reflects the maximum wick height that the wick of a
yellow-flame type lamp can be turned up to prior to smoke
formation, a high smoke point of as close to 45 mm is
desirable.
[0060] The total sulphur content of the kerosene is below 0.3
ppm(m/m) as measured by ASTM 3120.
EXAMPLE 3
[0061] Light olefins in the carbon range C3 to C6 originating from
a High Temperature Fischer Tropsch plant located in Mossel Bay were
oligomerised over a proprietary zeolyte catalyst (COD 9) as
supplied by Sud Chemie. The oligomerisation reaction was performed
at moderate temperatures below 280.degree. C. and relatively high
pressures of 55-bar process for the oligomerisation reaction to
produce an oleffinic distillate with a Bromine Number of over 90 g
Br/10 g sample. The olefinic portion of the sample was hydrotreated
at moderate hydrotreating conditions in Diesel Hydrotreater unit
equipped with a cobalt molybdenum (Engelhard E 5256) catalyst, at
58 kPa, the WABT did not exceed 321.degree. C., the LHSV was
maintained at 0.6 while the Hydrogen to Hydrocarbon Ratio was 275.
A hydrotreated fraction boiling between about 170 to 250.degree. C.
is collected at a distillation column.
EXAMPLE 4
[0062] Light olefins in the carbon range C.sub.3 to C.sub.6
originating from a the High Temperature Fischer Tropsch plant
located in Mossel Bay were oligomerised over a proprietary zeolyte
catalyst (COD 9) as supplied by Sud Chemie. The oligomerisation
reaction was performed at moderate temperatures below 280.degree.
C. and relatively high pressures of 55 bar process were used for
the oligomerisation reaction to produce an oleffinic distillate
with a Bromine Number of over 90 g Br/100 g sample. This distillate
was hydrotreated in one step using a high Nickel content commercial
catalyst as supplied by Sud Chemie. (Sud Chemie G134) The catalysts
(about 270 cc) were loaded into a pilot plant reactor in a graded
bed format and diluted with inert ceramics in the ratios of
catalyst to ceramics of, 0.2; 0.5; 170.0 and 650. The reactor
pressure was maintained at 58 bar, the WABT did not exceed
220.degree. C., the LHSV was maintained at 0.9 and a third of the
product was recycled back to the feed.
[0063] The one step hydrotreated distillate was fractioned by means
of a true boiling point distillation apparatus to yield a kerosene
fraction in the boiling range 170.degree. C. to 250.degree. C. This
kerosene was found to contain less than 0.1% v/v aromatics and no
detectable polyaromatic hydrocarbons.
EXAMPLE 5
[0064] Light olefins in the carbon range C3 to C6 originating from
a the High Temperature Fischer Tropsch plant located in Mossel Bay
were oligomerised over a proprietary zeolyte catalyst (COD 9) as
supplied by Sud Chemie. The oligomerisation reaction took place at
moderate temperatures below 280.degree. C. and relatively high
pressures of 55 bar process were used for the oligomerisation
reaction to produce an olefinic distillate with a Bromine Number of
over 120 g Br/100 g sample. This distillate was hydrotreated in one
step using a supported Platinum commercial catalyst (Axens LD402).
The catalyst (270 cc) was loaded into a pilot plant a graded bed
format and diluted with inert ceramics. The reactor pressure was
maintained at 60 bar, the WABT did not exceed 230.degree. C., the
LHSV was maintained at 0.9 and a portion of the product was
recycled.
[0065] The one step hydrotreated distillate was fractioned by means
of a true boiling point distillation apparatus to yield a kerosene
fraction in the boiling range 170.degree. C. to 250.degree. C. This
kerosene was found to contain less than 0.1% v/v aromatics.
* * * * *