Note: Descriptions are shown in the official language in which they were submitted.
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269~2-~1
The present :invention relates to a process for the
production oE a carburettor fuel, in w'hich the light oi'l t'hal:
originates from coal is treated in a refining staqe and a sub--
sequent reforming stage.
It is known that carburet-tor fuels extracted from coal
are highly aromatic as a result oE the molecular construction of
-the coal from condensed aromatics and have a benzol content that
is relatively high, namely, between 10 and 20~-wt.
This high benzol content is undesirable on account of
the toxic characteristics of the benzol.
Measures to decrease the benzol content depend on the
fact that the concentration oE benzol can be reduced by blending
with carburettor fuels that do not contain as much benzol. This
means that low benzo]-content carburettor fuels, mostly of mineral
oil origin, are available, which will not always be the case in an
autarkically operating coal liquification plant.
The present invention seeks to provide a process of
the kind discussed above with w'hich a low benzol, high octane
environmentally benign carburettor fuel can be obtained directly,
this preferably having oc-tane ratings (RO~/MON) of at least 98/88
without the addition of octane-rating increasing additives; this
process should thus operate regardless of the availability of
low-benzol content additive components.
As a -technical solution, it is proposed that in a pro-
cess of the -type described in the introduction hereto a nuclear or
core fraction with tne rela-tively hig'nest benzol content is
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7~;~;. J
distilled off from the reformate (application reEormate), arld that
the two remaining reformate fractions are comhined anc1 used
together as a car~uretto:r fuel,and that thi.s carburettor fuel. has
a benzol content of at most 5~-wt.
Accordiny to the present invention there is provided a
process for preparing a carburettor fuel in which light oil origi-
nating from coal is treated in a refining stage and a subsequent
re-forming stage, the process comprising distiLling -the reformate
(applica-tion reEormate), removing a core fraction relatively high
in benzol content, and combining the other fractions -to form a
carburet-tor fuel having a benzol content not exceeding about 5% by
weight.
A carburettor fuel extracted in this way has the advan-
tage that the octane rating is as gxeat or greater than the octane
rating of the application reformate, despite the extensive
reduction of the benzol content, withou-t the need for additive
components or additives to increase the octane rating and are
environmentally hazardous, whereby such a carburet-tor fuel has
octane ratings (RON = Research Octane Number, MON = Motor Octane
Number) of 98/88 is achieved and can thus be used as a super fuel
according to DIN 51 600. At the same time, -the carbu~ettor fuel
according to the present invention has a suitably low ben~ol
content, preferably 5%-wt, so that the relevant state regulations
regarding benzol content can be met without difficulty. In
addition to -this, using the process according to the present
inven-tion one ob-tains a fraction -that is highly enriched with
benzol, and which because of its high concentration of henzol can
a Jo
be further used as a valuable chemlcal raw material. ParafELns
and naphthenes occur at high concentrations, and these can be use(l
as solvents or in the production ox oleflns by lcnown mcthods.
Surprisingly, it was found that by rectiEication or
fractionation it is possible to separate high~benzol content frac-
tions from the reformate that originates from coal without
reducing the RON/MON ratings of the remaining reEormate, even
though -the benzol that has a favourable effect on the octane
rating is removed.
The reformate (application reformate) is produced as
follows, preferably from light coal oil. The conversion of the
coal to a carburettor fuel (benzene) takes place in several
stages. In -the first stage (the sump phase) the coal is converted
to a crude coal oil (medium oil and crude benzene) in the presence
of finely divided catalysts, by means o hydrogen at a suitable
pressure and temperature. The crude benzene is then refined in a
subsequent refining stage, over refining catalysts, in the pres-
ence of hydrogen at a high pressure (50 - 100 bar = 50-100 . 105
Pa) and at a high temperature (350 - 400~C). During refining, the
sulfur, nitrogen and oxygen heteroatoms that are catalyst
poisons for the reform contact, and that are present, organically
bound in the oil, are removed until only traces remain (less than
1 ppm). The refined benzene has a relatively low octane number
and does not meet the RON/MON of 98/88 stipulated by DIN 51 600.
Reforming must be carried out in order to improve octane
rating. This is done in the usual manner by reform contact using
pla-tinum or platinum/rhenium at 10 - 30 bar (= 10 - 30 .105 Pa)
hydrogen pressure and approximately 500C. Within t'he reformer,
numerous reactions such as isomerisation, de~hydrocyclisation
reactions, oleEin formation, and aromatization ta'ke place. In the
raEfinates that originate from coal ancl contain high
concentrations ox naphthenes (-thus hydrated aromaticfi) it i5 t'he
isomerisation-aro~atisa-tion reaction that is predominant. The
naphthenes, the cyclohexane and the me-thylcyclopentane forln benzol
in the reformer. Depending on process conditions within t'he
reformer, the benzol content in the coal benzene will be between
10 and 20%-wt.
Using such an application reforma-te, the method
according to the present inventicn can give the above discussed
advantages. According to one embodimen-t of the invention, the
application reformate has a boiling point from 40 to 200C and an
octane rating RON or MON prom greater than 98 or 88, respectively.
Fundamentally, however, it is possible that, besides -the light
coal oil already discussed, naphtha from a medium coal oil can
also be subjected to the process according to the present
invention, with some success, al-though this naphtha should not
come Erom a hydrocracking process, since such an application
product is very highly isomerized. Accordingly, a naphtha
obtained from a medium coal oil by hydrotreating i5 to be under-
stood as a light coal oil in the sense of the present invention,
and this is subjected to the reEorming stage and -the distlllation
stage according to the present invention. The conditions pre-
ferred for the hydrotreating can be ascertained by reference to
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Erdoel und Kohle--Er.d~ Petrochemie vereiniqt mit
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Brennstoffchemle, Vol. 36, :L9~3, pp. 370-72~
According to a particul.ar embodiment of the present
invention, the boillng point of thy nuclear :Eraction that is to be
distilled o:Ef is between 65 and 85C.
According to a further embodiment, in a re-forming that
is carried out in several stages, the first stage is carried out
under conditions that are particularly favourable for the
formation o:E benzol, whereupon the nuclear Eraction is distilled
off in subsequent reEorming stages toyether, under such conditions
that the reformate that occurs and used all together as carbu-
rettor fuel. is isomerized as extensively as possible. These
measures lead to particularly good results in the sense of the
present invention.
The invention will be -further described with reference
to the following example and the accompanying drawing (flow chart)
which ls a flow chart illustrating a process according -to the
invention.
Example
In the process according to the presen-t invention, a
reformate of coal origin (flow 1 in the flow chart appended here-
to) is decompose by rectification into three fractions (flow 2;
flow 3 and flow 4). Flow 2 consists of a low-boiling point hydro-
carbon that contains varying proportions of benzol, according to
separating efficiency and manner of running -the rectification
column, the proportion being, in general, lower Han 5~0
Flow 3 is a :Eraction in which t'he benzo'L is enrich0d and
contains -the accompanying hydrocaxborls that are specif:ic for the
coa] oil. Flow 4 contains the 'hig'her boi:Ling point hydrocarbons
of the applicatlon reformate and benzo:L proportions that vary
depending on the .separating e:Eficiency and manner of running the
rectification column, generally less than 5%.
Flow 5, flows 2 and combined, is the low~benzol car-
burettor fuel with a benzo]. content of less than 5~.
he usual packed columns or bell-bottom co]umns can be
used for rec-tification.
The benzol--at a high level of purity--can be extracted
as a valuable chemical raw ma-terial, using known extraction
methods. The remaining parts, consisting of paraffins and naph-
thenes,can be used as solvents or in the production of olefins,
according to known methods.
When 100 parts my weig'nt of a reformate originating from
coal are used, in general 5 - 15 parts-weight of flow I, 10 - 25
parts-weight flow 3, and 60 - 85 parts--weigh-t flow 4. However,
the parts depend on the composition of the re-Eormate and can form
other proportions in the event o-f different coal oil processing,
from the view point of -the low-benzol ca.rburettor fuel.
The boiling section of flow 3 must be such -tha-t ul-ti-
mately, in flow 5, a benzol content of less than 5%-wt is
obtained.
In all the tests conducted according to the process as
in the present invention, the measurement o RON/MON of the indi-
vidual flows revealed, surprisingly, that -the flow 3 had a much
r7 ¢~
lower octane nutmber, despite a higher benzo] content (Benzol RON
greater than 100), than the application refortnate, nameLy, ROI;I/MON
83/76. As a consequence the octane number of flow 5 was unexpect-
edly high, despite the removal of the high-octane but erlvironmerlt-
ally hazardous benzol.
Thus, 19 parts-wt of a fraction--boiling from 65 - 85C
(flow 3)--are isolated from a reformate with a RON/MON of
99.3/88.0, produced in conventional manner and originating from
coal, having a benzol content of 12 parts-wt. In this fraction,
there were approximately 50~-wt benzol and RON/MON of 83/76 were
measured. The resulting low-benzol carbure-ttor fuels (61
parts-wt, flow 5) reached a RON/MON of 100/89 with a residual
benzol content of ~.6~-wt. A 15- floor charged-body column with a
reflux ratio of 1:2 was used as the rectification apparatusO
