Note: Descriptions are shown in the official language in which they were submitted.
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- 1 -
FUEL COMPOSITIONS
The present invention relates to fuel compositions
comprising a gas oil base fuel, particularly to such
compositions containing a levulinate ester, and to their
preparation and use.
It is known to blend together two different fuel
components so as to modify the properties and/or the
performance, e.g. engine performance, of the resultant
composition.
Known diesel fuel components include the so-called
"biofuels" which derive from biological materials.
Examples include levulinate esters.
Levulinate esters (esters of levu.=Linic acid) and
their preparation by reaction of the appropriate alcohol
with furfuryl acetate are described in Zh. Prikl. Khim.
(Leningrad) (1969) 42(4), 958-9, and in particular the
methyl, ethyl, propyl, butyl, pentyl and hexyl esters.
WO-A-94/21753 discloses fuels for internal
combustion engines, including both gasoline and diesel
fuel, containing proportions (e.g. 1 to 90%v, 1 to 50%v,
preferably 1 to 20%v) of esters of C4__6 keto-carbonic
acids, preferably levulinic acid, with C1-22 alcohols.
Esters with Cl_8 alcohols are described as being
particularly suitable for inclusion in gasolines, and
esters with C9-22 alcohols are described as being
particularly suitable for inclusion in diesel fuels.
The examples in WO-A-94/21753 are all of the
inclusion of quantities of levulinate esters in
gasolines, for improvement in octane numbers (RON and
MON).
WO-A-03/002696 discloses a fuel composition
incorporating levulinic acid, or a functional derivative
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WO 2007/012585 PCT/EP2006/064396
- 2 -
thereof, with the object of providing more oxygen by
volume than ethanol or traditional oxygenates such as
MTBE or ETBE, giving little or no increase in fuel Reid
vapour pressure and little or no effect on the flash
point of the base fuel. The functional derivative is
preferably an alkyl derivative, more preferably a C1-10
alkyl derivative. Ethyl levulinate is said to be
preferred, with methyl levulinate a preferred
alternative. The levulinic acid or functional derivative
is preferably used to form 0.1 to 5%v of the fuel.
Current commercially available compression ignition
(diesel) engines tend to be optimised to run on fuels
having a desired specification. Moreover, the conditions
under which the engine is required to operate can affect
the manner in which a fuel composition in the engine will
behave. In particular, as the atmospheric temperature
falls, a fuel that is a single-phase hom.ogeneous liquid
at normal temperatures may become a multiphase liquid as
certain components either (i) freeze (forming solid wax)
or (ii) become immiscible in the bulk liquid and form a
separate liquid layer. The onset of wax: formation on
cooling is characterised by a change in the transparency
of the fuel and the temperature at which. this occurs is
termed the "Cloud Point" of the fuel. If, on cooling,
the Cloud Point is preceded by the formation of a
separate liquid phase, the temperature at which this
occurs is termed the "Phase separation temperature".
Diesel fuel specifications such as ASTM D975-02 (USA) and
EN590 (Europe) include limits on Cloud Point temperature
in order to ensure that diesel fuel remains fluid at the
lowest anticipated service temperature and that blocking
of fuel filters by wax is prevented. For trouble free
operation, it is also desirable that the diesel fuel in
the fuel tank remains homogeneous, sincE: the composition
CA 02616080 2008-01-21 '
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v.nsuit~ble ~s a Euel ~~r th~ engiraew 2'h'~ b1enc~.zngg of a
staridar~ ~oxtmerc~.a1 c1 ee1 bass fuel with ~L1iefueL
components, tO modify th ov~rall fu~l proprt.L~~ ~nd/~
perform~nc~, c~ri therefore have an adver~i irn.pct on the
pereorm~n.c~ af the blend in the englnes for which it is
intended'~
For the above reason, it i~ de~arable ~or any diesel
;u~i. blend to have an overall specification as c1ose a~
~~ ~~~sib1e to that of the standaz~d co~m~~cia11~ vailable.
di~s~1 b&fue.ls for whzch engines tend to be optlmised.
Thi~ ~an, howevÃz~ be difficult to chieirb~cause
ar~~ ~dditionaZ fuel +~on~~~~ent is 1ike1y to aLtr th~
~~~perties and perfo'm'~.rice of the base fuel. l~or~ovr
15 th~ properti~~ ~f t b1~nd, In ~arta.cula~ its efect~ ~r
low t~mp~.rature PeTf~Ernan, ar~ not &,ways
st~aightforward ~~ ~~edict om ~~~ ~~~~ti~s c t
constlltuer~~ fU~1S alonà i 1
It has now sux~pxisa.ri~ly 1ei fcurad that i~a fu~l
20 comp+~sita.On~ ~omprising a gas oil base fuel ~nd, an ~licy~,
1~vu1ix.t, th phase separation temperature o~ the fuel
com.posilta.cn idepd~z.t upon th~ leve1' of a~.noriatic
ox~~tituerat5 in th~ base fuel ~ In particular, th~ ph~~~
~~~~ration teirtp~ratur~ 15 1OW~r~c1 when the ti~~~~l of
~~ aromati~ ~onstituents is incread. Mor~cver, at ~
~~~ti cu;-ar t~mp~ratur, if the 3evel of arortatic
.
~onsta.tuents is incr~ased~ the arnount of a1~yl levullnate
that can be incorporated in a horn~g~rleots mixtl~lr~ ~s
inc;raec.
30 Ti accor~ance with the pes~nt .invention Ih~~~ i~
prov1ded a fu~1 cOmpo~itiOrn mprli ~a.ng a ga oi1 base
fuel, an alkyl. levulzn~t~ and ~rs~ or more add,i~iona1
com~~~eEi'c$r each of which comporent'~ ~onta1ns w~n~ or more
a~omata.c constitu~ntS, wherea.n ~aid additiona3. ~ornLox~ent~
35 are present a,n th~ amOur~t o~ 1 to 5O%m of ~aid fuel
com~~sit;Lon.
.'.:=='=:~=i7ti~:.a::.M:.=.'.f~'.'rJh :~~:':
,~ 4 ti=.%=. .
::~red at the EPO Qn May 24, 2007 15:52:49. R
AMENQEQ SHEET
CA 02616080 2008-01-21
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Tn ~~~~rdance with the present ir~~ention there is
9
a1].~o p'ovided a methcc of reduca.ng th~ phase s~az'at.a.on
tem~~~~tur~ v~ a fu~l ~ompositiori comprising a gas oil
btse fuel ad an alky1 1evulina~~, which m~tho' compri~es
incre~siz~~ the level of aromata~ ~onstitucrit~ In the fuel
cQm~~s;i.ti.on, prefe~ably by a.ncoa~poating in this fu~l
coposita.or, on.e or m.ore a~ditional coanponen~~ ~ ~~ch of
which cQm~onents CQnt~ins one O] m~~e aromatic
constituents 10 In a~~~rdance with the pr~~ent invention there is
further provided use iri a fuÃl composition comp~a~sing a
gas oil ba~e fu.Ã1 and an a1.ky1 1evti1in~t~ of o~ae o~ amor~
~dditional ~ompon.~nt~ , each of which oomponent cantains
on~ ~r m~~e arom&tic corstituentsr f~r the pu~~~~~~ of
r~educing the p,hase separation t~mper~tur~ of t~fuel
compo~iti~n.
Iri accordarice with th~ preser~t invera.ta.on, :he'e i~
stil1 further provi~ed a met~od of operating a
compr~s~ion ignition engi.n~ ~~~~~r a vihicZc wMch i~
powered by such an ~ngiri~, which m~t~od i~~Q1ves
introducing into a combustion chamber of the eflgine a
.
fuel ~omp~~ition a~ccrdinq to the s~rit i,nvei~ta.an,
2n a~~~~~anc with th~ prs~nt inveflta,can ;h~re is
s'~il1 further ~~ovi~ed & m~th~d of operatin~ ~ ~eating
appI~.ar~~~ ~~ovided with a btrn~r, which m~thod coiiprises
supplying t~ said burne.r a fuel composition acioxdi~~ ~o
the present inventa.on. Tni accordanwith th~ present mraverition ~:h~re 3s
still euxtri~~ ~~~vi~ed a procss for th~ pr~pa.t&tiorr of ~
fu&composition. whic.h, prccinvo1ve~ blending a gas
, :iL base fu,e1 ~ an alkyl evulinate an~ oaie or xoox'e
' additiona1 component~ ~ each ~~ which compor~entconta1ns
one or mox~e aromatic constituents, wherein sa.id
q additional components are present in the amount of 2 to
5Orom ~~ said fu~1 composa.tion.
::{ed at the EPO on May24, 2007 15:52.49. P~
::,y::h;'..ti=:.:;.=::.;::,4.,;.., ,
. . A MEN pED S NEET
:'r :. ... . . ...
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WO 2007/012585 PCT/EP2006/064396
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Preferably, said alkyl levulinate iti; selected from
C2_8 alkyl levulinates, more preferably ethyl levulinate,
n-propyl levulinate, n-butyl levulinate, n-pentyl
levulinate, 2-hexyl levulinate and 2-ethyl hexyl
levulinate, still more preferably ethyl levulinate,
n-butyl levulinate or n-pentyl levulinate, most
preferably ethyl levulinate.
Preferably, said additional components are selected
from materials which are suitable to be blended with fuel
compositions, such as for example (i) a refinery product
stream with an aromatic content higher than that of the
base fuel, or (ii) an aromatic solvent, e.g. SHELLSOL AB
(available ex. Shell companies), boiling in the normal
temperature range of gas oil.
Preferably, the concentration of said additional
component(s) in the fuel composition accords with one or
more of the following parameters:-
(i) at least lom; (ii) at least 5%m; (iii) at least
l0om (iv) at least 15%m; (v) up to 25%m; (vi) up to 30%m;
(vii) up to 40%m, (viii) up to 50%m,
with ranges having features (i) and (viii), (ii) and
(vii), (iii) and (vi), and (iv) and (v) respectively
being progressively more preferred.
Preferably, the concentration of aromatic
constituents in the fuel composition containing said
additional component(s) accords with one or more of the
following parameters:-
(i) at least 1om; (ii) at least 5%m; (iii) at least
l0om (iv) at least 20%m; (v) up to 30%m; (vi) up to 35%m;
(vii) up to 40%m, (viii) up to 50%m,
with ranges having features (i) and (viii), (ii) and
(vii), (iii) and (vi), and (iv) and (v) respectively
being progressively more preferred.
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Preferably, said phase separation temperature of
said fuel composition is reduced by at least 3 C, more
preferably by at least 5 C, still more preferably by at
least 10 C, and most preferably by at least 20 C.
Preferably, said phase separation temperature of
said fuel composition is below -5 C, more preferably
below -10 C, still more preferably below -20 C, and most
preferably below -30 C.
In all aspects of the present invention, blends of
two or more of the alkyl levulinates may be included in
the fuel composition. In the context of the present
invention, selection of the particular ccmponents of said
blends and their proportions is dependent upon one or
more desired characteristics of the fuel composition.
The present invention may be used tc formulate fuel
blends which are expected to be of particular use in
modern commercially available diesel engines as
alternatives to the standard diesel base fuels, for
instance as commercial and legislative pressures favour
the use of increasing quantities of organically derived
"biofuels".
In the context of the present invention, "use" of a
fuel component in a fuel composition means incorporating
the component into the composition, typically as a blend
(i.e. a physical mixture) with one or more other fuel
components, conveniently before the composition is
introduced into an engine.
The fuel composition will typically contain a major
proportion of the base fuel, such as from 50 to 99%v,
preferably from 50 to 98%v, more preferably from 80 to
98%v, most preferably from 90 to 98%v. The proportions
of the alkyl levulinates will be chosen t.o achieve the
desired degree of miscibility, i.e. phase: separation
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temperature, and may also be influenced by other
properties required of the overall composition.
The fuel compositions to which the present invention
relates include diesel fuels for use in automotive
compression ignition engines, as well as in other types
of engine such as for example marine, railroad and
stationary engines, and industrial gas oils for use in
heating applications (e.g. boilers).
The base fuel may itself comprise a mixture of two
or more different diesel fuel components, and/or be
additivated as described below.
Such diesel fuels will contain a base fuel which may
typically comprise liquid hydrocarbon middle distillate
gas oil(s), for instance petroleum derived gas oils.
Such fuels will typically have boiling points within the
usual diesel range of 150 to 400 C, depending on grade
and use. They will typically have a density from 750 to
900 kg/m3, preferably from 800 to 860 kg/rn3, at 15 C
(e.g. ASTM D4502 or IP 365) and a cetane number (ASTM
D613) of from 35 to 80, more preferably from 40 to 75.
They will typically have an initial boilirlg point in the
range 150 to 230 C and a final boiling po~_nt in the range
290 to 400 C. Their kinematic viscosity at 40 C (ASTM
D445) might suitably be from 1.5 to 4.5 rrm2/s.
Such industrial gas oils will contairi a base fuel
which may comprise fuel fractions such as the kerosene or
gas oil fractions obtained in traditional refinery
processes, which upgrade crude petroleum f:eedstock to
useful products. Preferably such fractioris contain
components having carbon numbers in the range 5 to 40,
more preferably 5 to 31, yet more preferably 6 to 25,
most preferably 9 to 25, and such fractior.is have a
density at 15 C of 650 to 1000 kg/m3, a kinematic
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viscosity at 20 C of 1 to 80 mm2/s, and a boiling range
of 150 to 400 C.
Optionally, non-mineral oil based fuels, such as
bio-fuels or Fischer-Tropsch derived fuels, may also form
or be present in the fuel composition. Such
Fischer-Tropsch fuels may for example be derived from
natural gas, natural gas liquids, petroleum or shale oil,
petroleum or shale oil processing residues, coal or
biomass.
The amount of Fischer-Tropsch derived fuel used in a
diesel fuel composition may be from 0.5 to 100%v of the
overall diesel fuel composition, preferably from 5 to
75%v. It may be desirable for the composi_tion to contain
10ov or greater, more preferably 20%v or c[reater, still
more preferably 30%v or greater, of the Fischer-Tropsch
derived fuel. It is particularly preferred for the
composition to contain 30 to 75%v, and particularly 30 or
70%v, of the Fischer-Tropsch derived fuel. The balance
of the fuel composition is made up of one or more other
fuels.
An industrial gas oil composition will preferably
comprise more than 50 wt%, more preferabl'y more than
70 wt%, of a Fischer-Tropsch derived fuel component.
Such a Fischer-Tropsch derived fuel component is any
fraction of the middle distillate fuel range, which can
be isolated from the (hydrocracked) Fischer-Tropsch
synthesis product. Typical fractions will boil in the
naphtha, kerosene or gas oil range. Preferably, a
Fischer-Tropsch product boiling in the kerosene or gas
oil range is used because these products are easier to
handle in for example domestic environments. Such
products will suitably comprise a fractiori larger than
90 wt% which boils between 160 and 400 C, preferably to
about 370 C. Examples of Fischer-Tropsch derived
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kerosene and gas oils are described in EP.-A-0583836,
WO-A-97/14768, WO-A-97/14769, WO-A-00/11116,
WO-A-00/11117, WO-A-01/83406, WO-A-01/83648,
WO-A-01/83647, WO-A-01/83641, WO-A-00/20535,
WO-A-00/20534, EP-A-1101813, US-A-5766274,. US-A-5378348,
US-A-5888376 and US-A-6204426.
The Fischer-Tropsch product will suitably contain
more than 80 wt% and more suitably more than 95 wt% iso
and normal paraffins and less than 1 wt% aromatics, the
balance being naphthenics compounds. The content of
sulphur and nitrogen will be very low and normally below
the detection limits for such compounds. For this reason
the sulphur content of a fuel composition containing a
Fischer-Tropsch product may be very low.
The fuel composition preferably contains no more
than 5000ppmw sulphur, more preferably no more than
500ppmw, or no more than 350ppmw, or no more than
150ppmw, or no more than 100ppmw, or no more than 50ppmw,
or most preferably no more than lOppmw sulphur.
In addition to the alkyl levulinates and the
above-mentioned one or more additional coinponents, each
of which components contains one or more aromatic
constituents, the fuel composition of the present
invention may, if required, contain one or more additives
as described below.
The base fuel may itself be additivated (additive-
containing) or unadditivated (additive-free). If
additivated, e.g. at the refinery, it will contain minor
amounts of one or more additives selected for example
from anti-static agents, pipeline drag reducers, flow
improvers (e.g. ethylene/vinyl acetate copolymers or
acrylate/maleic anhydride copolymers), lubricity
additives, antioxidants and wax anti-settling agents.
Detergent-containing diesel fuel additives are known
and commercially available. Such additives may be added
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to diesel fuels at levels intended to reduce, remove, or
slow the build up of engine deposits.
Examples of detergents suitable for use in fuel
additives for the present purpose include polyolefin
substituted succinimides or succinamides of polyamines,
for instance polyisobutylene succinimides or
polyisobutylene amine succinamides, aliphatic amines,
Mannich bases or amines and polyolefin (e.g.
polyisobutylene) maleic anhydrides. Succinimide
dispersant additives are described for example in
GB-A-960493, EP-A-0147240, EP-A-0482253, EP-A-0613938,
EP-A-0557516 and WO-A-98/42808. Particularly preferred
are polyolefin substituted succinimides such as
polyisobutylene succinimides.
The additive may contain other compor.tents in
addition to the detergent. Examples are lubricity
enhancers; dehazers, e.g. alkoxylated phenol formaldehyde
polymers; anti-foaming agents (e.g. polyether-modified
polysiloxanes); ignition improvers (cetane improvers)
(e.g. 2-ethylhexyl nitrate (EHN), cyclohexyl nitrate,
di-tert-butyl peroxide and those disclose(J in
US-A-4208190 at column 2, line 27 to coluinn 3, line 21);
anti-rust agents (e.g. a propane-1,2-diol semi-ester of
tetrapropenyl succinic acid, or polyhydric alcohol esters
of a succinic acid derivative, the succinic acid
derivative having on at least one of its alpha-carbon
atoms an unsubstituted or substituted aliphatic
hydrocarbon group containing from 20 to 500 carbon atoms,
e.g. the pentaerythritol diester of
polyisobutylene-substituted succinic acid); corrosion
inhibitors; reodorants; anti-wear additives;
anti-oxidants (e.g. phenolics such as
2,6-di-tert-butylphenol, or phenylenediamines such as
N,N'-di-sec-butyl-p-phenylenediamine); metal
deactivators; and combustion improvers.
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It is particularly preferred that the additive
include a lubricity enhancer, especially when the fuel
composition has a low (e.g. 500 ppmw or '_ess) sulphur
content. In the additivated fuel composition, the
lubricity enhancer is conveniently preserit at a
concentration of less than 1000 ppmw, preferably between
50 and 1000 ppmw, more preferably betweeri 100 and 1000
ppmw. Suitable commercially available lubricity
enhancers include ester- and acid-based additives. Other
lubricity enhancers are described in the patent
literature, in particular in connection with their use in
low sulphur content diesel fuels, for exanlple in:
- the paper by Danping Wei and H.A. Spikes, "The
Lubricity of Diesel Fuels", Wear, III (1986) 217-235;
- WO-A-95/33805 - cold flow improvers to enhance
lubricity of low sulphur fuels;
- WO-A-94/17160 - certain esters of a carboxylic
acid and an alcohol wherein the acid has from 2 to 50
carbon atoms and the alcohol has 1 or more carbon atoms,
particularly glycerol monooleate and di-isodecyl adipate,
as fuel additives for wear reduction in a diesel engine
injection system;
- US-A-5490864 - certain dithiophosphoric diester-
dialcohols as anti-wear lubricity additives for low
sulphur diesel fuels; and
- WO-A-98/01516 - certain alkyl aromatic compounds
having at least one carboxyl group attached to their
aromatic nuclei, to confer anti-wear lubricity effects
particularly in low sulphur diesel fuels.
It is also preferred that the additive contain an
anti-foaming agent, more preferably in combination with
an anti-rust agent and/or a corrosion inhibitor and/or a
lubricity additive.
Unless otherwise stated, the (active rnatter)
concentration of each such additional component in the
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additivated fuel composition is preferab=Ly up to
10000 ppmw, more preferably in the range from 0.1 to 1000
ppmw, advantageously from 0.1 to 300 ppmw, such as from
0.1 to 150 ppmw.
The (active matter) concentration of any dehazer in
the fuel composition will preferably be in the range from
0.1 to 20 ppmw, more preferably from 1 to 15 ppmw, still
more preferably from 1 to 10 ppmw, advantageously from 1
to 5 ppmw. The (active matter) concentrat:ion of any
ignition improver present will preferably be 2600 ppmw or
less, more preferably 2000 ppmw or less, conveniently
from 300 to 1500 ppmw.
If desired, the additive components, as listed
above, may be co-mixed, preferably togethe:r with suitable
diluent(s), in an additive concentrate, and the additive
concentrate may be dispersed into the fuel, in suitable
quantity to result in a composition of the present
invention.
In the case of a diesel fuel composition, for
example, the additive will typically contain a detergent,
optionally together with other components as described
above, and a diesel fuel-compatible diluent, which may be
a carrier oil (e.g. a mineral oil), a polyether, which
may be capped or uncapped, a non-polar solvent such as
toluene, xylene, white spirits and those sold by Shell
companies under the trade mark "SHELLSOL", and/or a polar
solvent such as an ester and, in particular, an alcohol,
e.g. hexanol, 2-ethylhexanol, decanol, isotridecanol and
alcohol mixtures such as those sold by Shell companies
under the trade mark "LINEVOL", especially LINEVOL 79
alcohol which is a mixture of C7_9 primary alcohols, or a
C12-14 alcohol mixture which is com.mercialLy available.
The total content of the additives may be suitably
between 0 and 10000 ppmw and preferably below 5000 ppmw.
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Preferably, the alkyl levulinate concentration in
the fuel composition accords with one or more of the
following parameters:-
(i) at least lov; (ii) at least 2ov; (iii) at least
3%v; (iv) at least 4%v; (v) at least 5ov;' (vi) up to 6%v;
(vii) up to 8%v; (viii) up to 10ov, (xi) up to 12%v, (x)
up to 35%v, with ranges having features {.i) and (x), (ii)
and (ix), (iii) and (viii), (iv) and (vii), and (v) and
(vi) respectively being progressively more preferred.
In this specification, amounts (concentrations, %v,
ppmw, wt%) of components are of active matter, i.e.
exclusive of volatile solvents/diluent materials.
The present invention is particularly applicable
where the fuel composition is used or intended to be used
in a direct injection diesel engine, for example of the
rotary pump, in-line pump, unit pump, electronic unit
injector or common rail type, or in an indirect injection
diesel engine. The fuel composition may be suitable for
use in heavy and/or light duty diesel engines.
As mentioned above, it is also applicable where the
fuel composition is used in heating applications, for
example boilers. Such boilers include standard boilers,
low temperature boilers and condensing boilers, and are
typically used for heating water for commercial or
domestic applications such as space heating and water
heating.
The present invention may lead to any of a number of
advantageous effects, including good engine low
temperature performance.
The present invention will now be further described
by reference to the following Examples, in which, unless
otherwise indicated, parts and percentages are by weight,
and temperatures are in degrees Celsius:
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Fuels were blended with additives by adding said
additives to base fuel at ambient tempera-:ure (20 C) and
homogenising.
The following additives were used:-
ethyl levulinate (available ex. Avocado);
n-butyl levulinate (available ex. Aldrich.); and
n-pentyl levulinate (available ex. City Chemical or by
the reaction of 1-pentanol (available ex. Aldrich) with
levulinic acid (available ex. Aldrich)).
Examples
The miscibility of levulinates depends to some extent
on base fuel properties. Two base fuels representative
of the European market were chosen to explore this
effect, i.e. (1) Fuel A was a Dreyfuss ULSD, a
hydrotreated AGO having a cloud point of -27 C and an
aromatics content of 22%m; and (2) Fuel B was a Swedish
Class 1 AGO, which is a low density, low aromatics (4%m)
diesel fuel with a cloud point of -38 C. Both base fuels
met the EN590 specification.
The properties of Fuels A and B are givE:n in Table 1.
Table 1
Fuel A Fuel B
Density @ 15 C, 822 815
kg/m3
Distillation T50, 242 235
C _
Distillation T95, 304 272
C _
Cetane Number 54 54
Viscosity @40 C, 2.10 2.03
mm2/s
Sulphur, mg/kg 10 _ <5
Cloud Point, C -27 -38
Aromatics, %m 22 4
For screening purposes, a simple test method was
used to determine the room temperature (20"C) limit of
miscibility of ethyl levulinate. Accurately metered
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volumes of ester were added sequentially to a known
volume of diesel fuel in a 15m1 glass vial, shaken and
observed. The first appearance of haze was recorded as
the room temperature limit of miscibility for the
mixture. The results are shown in Table 2 and clearly
show that Fuel A, with the higher aromatic content,
solubilised more ethyl levulinate than Fuel B.
Table 2
Fuel A Fuel B
14%v 7%v
The miscibility of various alkyl levulinates was
measured using a method based on the ASTM D2500 "Cloud
Point" procedure. In this procedure, a sample of fuel
(40 ml) is cooled from ambient temperature (20 C) in a
series of thermostat baths maintained at progressively
lower temperatures. The sample is examined at 1 C
intervals as it cools to its wax cloud point. In
addition to the wax cloud point temperature described in
ASTM D2500, a further two temperatures were recorded
coinciding with the following observations, if they
occurred:
(1) the appearance of the first haze,
(2) the first sign of dropout of a separate liquid
phase.
In each case, cooling continued to the wax cloud point -
beyond which, no further phase separation could be
observed reliably because the sample became opaque.
Solutions of the esters ethyl levulinate, n-butyl
levulinate and n-pentyl levulinate in Fuel. A were blended
at various concentrations and the miscibility of each
blend was measured. The results are shown. in Table 3
below.
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Table 3
Phase separation temperature ( C)
Ester ethyl n-butyl n-pentyl
concentration levulinate levulinate levulinate
(ov)
2 W W _ w
3 W W _ W
4 -17 W _ W
-10 W _ W
6 -5* w _ w
8 7 W W
14 w w
W denotes that the mixture was cooled to the wax cloud point (-27 C
for Fuel A) without liquid separation; * = extrapolated value
The miscibility tests were repeated using Fuel B.
The results are shown in Table 4.
Table 4
Phase separation temperature ( C)
Ester ethyl n-butyl n-pentyl
concentration levulinate levulinate levulinate
(%v) 2 -26 W _ W
3 -10 w _ w
4 3 W _ W
5 5 -31* _ W
6 10* -26 _ w
8 - -22 -33
10 - -18 -28
W denotes that the mixture was cooled to the wax cloud point (-38 C
for Fuel B) without liquid separation; * = extrapolated value
It was found that, for each of Fuels A and B, when
the aromatic content was increased by addi_ng the solvent
"SHELLSOL AB" (ex. Shell), the phase separation
temperature was lowered throughout the rarige of
concentrations of ethyl levulinate. The results of tests
which demonstrate this effect are set out :Ln Table 5:
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Table 5
Phase separation temperature ( C)
Ethyl Fuel A Fuel A Fuel B Fuel B
levulinate (total plus (total plus
(ov) aromatics SHELLSOL aromatics SHELLSOL
22%m) AB (total 4om) AB(total
aromatics aromatics
40%m) 20%m)
2 W - -26 -41
3 w <-30 -10 -30*
4 -17 <-30 3 -22
-10 <-30 5 -15*
6 -5* <-30 10* -8
W denotes that the mixture was cooled to the wax 2loud point (-27 C
for Fuel A) without liquid separation; * = extrapolated value
