U.S. patent application number 12/161998 was filed with the patent office on 2009-06-25 for method of hydrogenolysis of wax and process for producing fuel base.
Invention is credited to Minoru Hatayama, Masahiro Higashi, Hiroyuki Seki.
Application Number | 20090159490 12/161998 |
Document ID | / |
Family ID | 38309093 |
Filed Date | 2009-06-25 |
United States Patent
Application |
20090159490 |
Kind Code |
A1 |
Seki; Hiroyuki ; et
al. |
June 25, 2009 |
METHOD OF HYDROGENOLYSIS OF WAX AND PROCESS FOR PRODUCING FUEL
BASE
Abstract
The hydrocracking method of wax of the invention is a
hydrocracking process wherein crude wax is subjected to
hydrocracking and the untreated wax fraction that is produced after
the hydrocracking is re-supplied for hydrocracking, and wherein
hydrocracking of the mixture of the crude wax and untreated wax
fraction is carried out in such a manner for a conversion ratio of
50-85% by mass from the wax fraction with a boiling point of
360.degree. C. or above to the light fraction with a boiling point
of below 360.degree. C. in the presence of a hydrocracking
catalyst. It is thereby possible to simultaneously achieve both an
increased heart-cut fraction yield (as the product of the
hydrocracking) and a reduced normal paraffin content in the
heart-cut fraction when the untreated wax is hydrocracked by a
bottom recycling system.
Inventors: |
Seki; Hiroyuki; (Kanagawa,
JP) ; Higashi; Masahiro; (Kanagawa, JP) ;
Hatayama; Minoru; (Kanagawa, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
38309093 |
Appl. No.: |
12/161998 |
Filed: |
January 18, 2007 |
PCT Filed: |
January 18, 2007 |
PCT NO: |
PCT/JP2007/050658 |
371 Date: |
July 24, 2008 |
Current U.S.
Class: |
208/27 |
Current CPC
Class: |
B01J 21/02 20130101;
C10G 2300/1022 20130101; B01J 2229/42 20130101; C10G 47/12
20130101; C10G 47/18 20130101; B01J 29/084 20130101; B01J 2229/20
20130101; C10G 2300/4081 20130101; B01J 35/023 20130101; C10G 47/16
20130101; B01J 29/126 20130101 |
Class at
Publication: |
208/27 |
International
Class: |
C10G 73/02 20060101
C10G073/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2006 |
JP |
2006-021291 |
Claims
1.-6. (canceled)
7. A hydrocracking process wherein crude wax is subjected to
hydrocracking and the untreated wax fraction that is produced after
the hydrocracking is re-supplied for hydrocracking, and wherein
hydrocracking of the crude wax and untreated wax fraction is
carried out in the presence of a hydrocracking catalyst in such a
manner that the conversion ratio is 50-85% by mass from the wax
fraction with a boiling point of 3600 and above to the light
fraction with a boiling point of below 360.degree. C.
8. The hydrocracking method according to claim 7, wherein the
hydrocracking catalyst contains USY-zeolite and at least one solid
acid selected from among silica-alumina, alumina-boria and
silica-zirconia.
9. The hydrocracking method according to claim 8, wherein the mean
particle size of the USY-zeolite is no greater than 1.0 .mu.m.
10. The hydrocracking method according to claim 8, wherein the
USY-zeolite content is no greater than 6% by mass based on the
total weight of the hydrocracking catalyst.
11. The hydrocracking method according to claim 7, wherein the
reaction temperature for hydrocracking of the crude wax and
untreated wax fraction is no higher than 370.degree. C.
12. A production method of a fuel base material comprising:
subjecting crude wax to hydrocracking; and resupplying for
hydrocracking an untreated wax fraction that is produced after the
crude wax hydrocracking; wherein the hydrocracking of the crude wax
and the untreated wax fraction is carried out in the presence of a
hydrocracking catalyst, in such a manner that a conversion ratio is
50-85% by mass, from a wax fraction with a boiling point of
360.degree. C. or above, to a light fraction with a boiling point
of below 360.degree. C.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hydrocracking method of
wax and to a production method of a fuel base material.
BACKGROUND ART
[0002] The stricter environmental standards for liquid fuels such
as gasoline and light oil that have been rapidly adopted in recent
years have led to rising hopes for clean, environmentally-friendly
liquid fuels with reduced sulfur or aromatic hydrocarbon contents.
One production process for such clean fuels is Fischer-Tropsch (FT)
synthesis which uses as starting materials hydrogen and carbon
monoxide obtained from gasification of asphalt or coal, or refining
of natural gas. FT synthesis allows production of liquid fuel bases
rich in paraffins and containing no sulfur, while simultaneously
allowing production of waxes (FT waxes) as well. FT waxes can also
be converted to heart-cut fractions (fuel bases such as kerosene
and light oil) by hydrocracking.
[0003] Techniques for producing fuel bases by hydrocracking of
waxes are also being investigated. For example, Patent documents
1-3 disclose hydrocracking processes using FT waxes as starting
materials.
[Patent document 1] International Patent Publication No.
2004/028688 [Patent document 2] Japanese Unexamined Patent
Publication No. 2004-255241 [Patent document 3] Japanese Unexamined
Patent Publication No. 2004-255242
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0004] Hydrocracking of wax usually leaves an untreated wax
fraction. In order to increase the maximum yield for the heart-cut
fraction, it is preferred to supply the untreated wax fraction for
additional hydrocracking. The reuse of an untreated wax fraction as
the starting material for hydrocracking will henceforth be referred
to as "bottom recycling", for convenience.
[0005] When a heart-cut fraction produced from hydrocracking of wax
is used as a fuel base, the normal paraffin content is preferably
low while the isoparaffin content is preferably high. In the case
of automobile gasoline, for example, a high normal paraffin content
results in an insufficient octane number. In the case of light oil,
a high normal paraffin content impairs the low-temperature flow
properties, often restricting its use as a commercial product.
[0006] However, little research has been carried out on processes
for high-yield production of isoparaffin-rich heart-cut fractions,
in the course of hydrocracking of untreated wax by a bottom
recycling system in the conventional hydrocracking method of wax
described above.
[0007] Production of heart-cut fractions in the field of petroleum
refining is typically accomplished by hydrocracking of reduced
pressure light oil, whereby it is possible to produce low-sulfur
light oil which, however, contains aromatic compounds. Recycling
methods for uncracked reduced pressure light oil (bottom residue)
with a fixed crack-per-pass have already been established, and many
types of industrial equipment for implementing them are in actual
operation.
[0008] On the other hand, virtually no data can be found for bottom
recycling in hydrocracking where the major component is normal
paraffin, such as with FT wax as explained above, and bottom
recycling of untreated wax has not been described. This is thought
to be due to the fact that the reactive properties of untreated wax
fractions differ significantly from those of raw material wax.
[0009] For example, in order to increase the heart-cut fraction
yield it is preferred to prevent lightening of the produced
heart-cut fraction by carrying out hydrocracking under mild
reaction conditions, but the normal paraffin content of heart-cut
fractions obtained under such reaction conditions tends to be
higher. On the other hand, the normal paraffin content of the
obtained heart-cut fraction can be reduced by employing more severe
reaction conditions for hydrocracking, although this tends to
promote overcracking of the produced heart-cut fraction and result
in a reduced heart-cut fraction yield. Thus, considering a
trade-off between increasing the heart-cut fraction yield and
reducing the normal paraffin content, and in light of the fact that
the carbon number distribution and molecular structure of untreated
wax differs from that of crude wax, it is necessary to select the
optimal reaction conditions for bottom recycling and efficient
production of a heart-cut fraction with low normal paraffin.
[0010] It is an object of the present invention, which has been
accomplished in light of these circumstances, to provide a
hydrocracking method of wax which can achieve both an increased
heart-cut fraction yield (as the target product of the
hydrocracking) and reduced normal paraffin content in the heart-cut
fraction during hydrocracking of untreated wax by a bottom
recycling system, as well as a production method of a fuel base
material.
Means for Solving the Problems
[0011] A result of much diligent research directed toward achieving
the object stated above, the present inventors discovered that the
aforementioned problems can be solved by carrying out hydrocracking
in such a manner that the hydrocracking conversion ratio satisfies
specific conditions during bottom recycling of untreated wax in the
process of wax hydrocracking, and the invention has been completed
upon this discovery.
[0012] Specifically, the hydrocracking method of wax of the
invention is a hydrocracking process wherein crude wax is subjected
to hydrocracking and the untreated wax fraction that is produced
after the hydrocracking is re-supplied for hydrocracking, and
wherein hydrocracking of the crude wax and untreated wax fraction
is carried out in the presence of a hydrocracking catalyst in such
a manner that the conversion ratio is 50-85% by mass from the wax
fraction with a boiling point of 360.degree. C. or above to the
light fraction with a boiling point of below 360.degree. C.
[0013] The production method of a fuel base material according to
the invention comprises a hydrocracking step wherein crude wax is
subjected to hydrocracking and the untreated wax fraction that is
produced after the hydrocracking is re-supplied for hydrocracking,
in which hydrocracking step hydrocracking of the crude wax and
untreated wax fraction is carried out in the presence of a
hydrocracking catalyst in such a manner that the conversion ratio
is 50-85% by mass from the wax fraction with a boiling point of
360.degree. C. or above to the light fraction with a boiling point
of below 360.degree. C.
[0014] The conversion ratio from the wax fraction with a boiling
point of 360.degree. C. or above to the light fraction with a
boiling point of below 360.degree. C. is the conversion ratio as
defined by formula (1) below. In formula (1), "weight of wax
fraction with boiling point of 360.degree. C. and above" means the
total weight of wax fractions with boiling points of 360.degree. C.
and above in the crude wax and untreated wax fraction, while
"weight of fraction with boiling point of below 360.degree. C."
means the weight of the fraction with a boiling point of below
360.degree. C. in the treated product obtained by the
hydrocracking.
[Formula 1]
[0015] Conversion ratio(% by mass)=(weight of fraction with boiling
point
of below 360.degree. C.)/(weight of wax fraction with boiling point
of 360.degree. C.
and above) (1)
[0016] According to the invention, the hydrocracking catalyst
preferably contains USY-zeolite and at least one solid acid
selected from among silica-alumina, alumina-boria and
silica-zirconia.
[0017] The mean particle size of the USY-zeolite is preferably no
greater than 1.0 .mu.m.
[0018] The USY-zeolite content is also preferably no greater than
6% by mass based on the total weight of the hydrocracking
catalyst.
[0019] The reaction temperature for the crude wax and untreated wax
fraction during the hydrocracking is preferably no greater than
370.degree. C.
EFFECT OF THE INVENTION
[0020] As mentioned above, the hydrocracking method of wax and fuel
base manufacturing process of the invention can achieve both an
increased heart-cut fraction yield (as the target product of the
hydrocracking) and a reduced normal paraffin content in the
heart-cut fraction, during bottom recycling of the untreated
wax.
BRIEF EXPLANATION OF THE DRAWINGS
[0021] FIG. 1 is an illustration showing an example of a fixed bed
reactor used for the invention.
EXPLANATION OF SYMBOLS
[0022] 1: Reaction column, 2: hydrocracking catalyst layer, 3:
distilling apparatus.
BEST MODE FOR CARRYING OUT THE INVENTION
[0023] Preferred modes of the invention will now be described in
detail.
[0024] FIG. 1 is an illustration showing an example of a fixed bed
reactor suitable for use according to the invention.
[0025] In the fixed bed reactor shown in FIG. 1, a hydrocracking
catalyst layer 2 is provided in a reaction column 1. At the top of
the reaction column 1 there is connected a line L1 for supply of
hydrogen into the reaction column 1, while a line L2 for supply of
the crude wax is connected upstream from the connection of the line
L1 with the reaction column 1. Also, at the bottom of the reaction
column 1 there is connected a line L3 for removal of the
hydrocracked decomposition product oil from the reaction column 1,
while the other end of the line L3 is connected to the distilling
apparatus 3. The distilling apparatus 3 is capable of fractionating
the light fraction with a boiling point of below 360.degree. C.
produced by the hydrocracking, from the unreacted wax fraction with
a boiling point of 360.degree. C. and above, and the fractionated
unreacted wax fraction is transported to a line L4 while the light
fraction is transported to a line L5. The end of the line L4 is
connected upstream from the connection of the line L1 with the
reaction column 1, while the unreacted wax fraction is introduced
into the reaction column 1 from the top of the reaction column 1
and re-supplied for hydrocracking (bottom recycling).
[0026] The crude wax used is preferably a petroleum-based or
synthetic wax comprising at least 70% by mass of C16 or greater and
preferably C20 or greater normal paraffins. As examples of such
waxes there may be mentioned petroleum-based waxes such as slack
wax and microwax, or synthetic waxes such as "FT wax" produced by
FT synthesis.
[0027] There are no particular restrictions on the hydrocracking
catalyst in the hydrocracking catalyst layer 2, but the
hydrocracking catalyst is preferably one comprising one or more
selected from among USY-zeolite, silica-alumina, silica-zirconia,
alumina-boria and silicoaluminophosphates (SAPO-11 or the like) as
the carrier, more preferably one comprising USY-zeolite and one or
more amorphous solid acids selected from among silica-alumina,
alumina-boria and silica-zirconia, and most preferably one
comprising USY-zeolite and alumina-boria.
[0028] When the hydrocracking catalyst contains USY-zeolite, the
mean particle size is preferably no greater than 1.0 .mu.m and even
more preferably no greater than 0.5 .mu.m. If the mean particle
size of the USY-zeolite exceeds 1.0 .mu.m, the heart-cut fraction
(the target product of the hydrocracking) will be lighter and its
yield will tend to be reduced.
[0029] The molar ratio of silica/alumina in the USY-zeolite is
preferably 25-80 and more preferably 28-50. A silica/alumina molar
ratio of less than 25 will tend to lower the selectivity of the
heart-cut fraction. On the other hand, while a silica/alumina molar
ratio of greater than 80 will not impair the selectivity of the
heart-cut fraction, the reaction temperature must be increased due
to the lower catalytic activity, and therefore the catalyst life
tends to be shorter.
[0030] The USY-zeolite content is preferably no greater than 6% by
mass, more preferably no greater than 4% by mass and even more
preferably no greater than 3% by mass based on the total weight of
the hydrocracking catalyst. A USY-zeolite content of greater than
6% by mass will tend to lower the selectivity of the heart-cut
fraction.
[0031] The hydrocracking catalyst may further contain a binder for
molding of the carrier. There are no particular restrictions on the
binder, but preferred binders include alumina and silica, with
alumina being especially preferred. The shape of the carrier is
also not particularly restricted, and it may be in a form of
particles, cylinders (pellets) or the like.
[0032] The hydrocracking catalyst preferably comprises a metal
belonging to Group VIII of the Periodic Table supported on the
aforementioned carrier. The supported metal is preferably nickel,
rhodium, palladium, iridium or platinum, with palladium and
platinum being preferred. Such metals may be supported alone or in
combinations of two or more.
[0033] When the hydrocracking catalyst of the hydrocracking
catalyst layer 3 contains such a metal, the metal is preferably
reduced in a reducing gas atmosphere such as hydrogen prior to
hydrocracking. The reducing conditions are not particularly
restricted, but preferably the reducing temperature is
300-360.degree. C. and the reducing time is 1-6 hours.
[0034] When wax hydrocracking is carried out using a fixed bed
reactor such as shown in FIG. 1, first the crude wax is used alone
for hydrocracking. During this first hydrocracking, the reaction
conditions are preferably selected so that the conversion ratio as
defined by formula (1) above is 50-85% by mass, with the
hydrocracking preferably being conducted for a prescribed time to
stabilize the catalytic activity of the hydrocracking catalyst
layer 2.
[0035] The cracked oil produced by hydrocracking using the crude
wax alone is transported from the reaction column 1 to the
distilling apparatus 3, for fractionation of the untreated wax
fraction with a boiling point of 360.degree. C. and above and the
light fraction with a boiling point of below 360.degree. C. The
untreated wax fraction with a boiling point of 360.degree. C. and
above is then introduced through the top of the reaction column 1
together with the crude wax, for hydrocracking of the mixture of
the crude wax and untreated wax fraction.
[0036] In order to simultaneously achieve an increased yield of
heart-cut fraction as the target product of the hydrocracking and a
reduced normal paraffin content in the heart-cut fraction, the
hydrocracking must be conducted in such a manner that the
conversion ratio as defined by formula (1) above is 50-85% by mass
and more preferably 60-78% by mass. If the conversion ratio is less
than 50% by mass, isomerization of normal paraffins to isoparaffins
will not proceed sufficiently, such that the normal paraffin
content of the obtained heart-cut fraction will not be adequately
reduced. If the conversion ratio exceeds 85% by mass, the heart-cut
fraction yield will be reduced as a result of overcracking.
[0037] The mixing ratio of the crude wax and untreated wax fraction
is not particularly restricted so long as the conversion ratio as
defined by formula (1) above is 50-85% by mass, but the untreated
wax fraction content is preferably 10-60% by mass and more
preferably 15-50% by mass based on the total of the crude wax and
untreated wax fraction.
[0038] The reaction conditions for hydrocracking of the mixture of
the crude wax and untreated wax fraction are also not particularly
restricted so long as the conversion ratio as defined by formula
(1) above is 50-85% by mass, but preferably the reaction
temperature is not above 370.degree. C. A reaction temperature
exceeding 370.degree. C. is not preferred for a clean fuel base
because aromatic compounds will tend to be produced. The reaction
pressure is also not particularly restricted, but the hydrogen
partial pressure is preferably 1-12 MPa and more preferably 2-6
MPa. In addition, the liquid space velocity of the mixture of the
crude wax and the unreacted wax fraction is not particularly
restricted but is preferably 0.2-5.0 h.sup.-1 and more preferably
0.5-3.0 h.sup.-1. A liquid space velocity of smaller than 0.2
h.sup.-1 will lead to problems such as requirement for an
excessively large reaction column, reduced selectivity of the
heart-cut fraction and inadequate isomerization. A liquid space
velocity of greater than 5.0 h.sup.-1 will require a higher
reaction temperature because of low activity, and the catalyst life
will thus be shortened. The hydrogen/oil ratio is not particularly
restricted but is preferably 200-850 NL/L and more preferably
350-650 NL/L.
[0039] The mode of the invention explained here accomplishes
hydrocracking of a mixture of crude wax and untreated wax in such a
manner that the conversion ratio as defined by formula (1) above is
50-85% by mass, thereby making it possible to simultaneously
achieve an increased heart-cut fraction yield (as the target
product of the hydrocracking) and a reduced normal paraffin content
in the heart-cut fraction.
[0040] The invention is not limited to this mode, however. For
example, although the untreated wax fraction and crude wax are
introduced as a mixture into the reaction column 1 according to
this mode, the untreated wax fraction and crude wax may instead be
introduced separately into the reaction column 1.
[0041] Also, while the position at which the untreated wax fraction
is introduced into the reaction column 1 is at the top of the
reaction column 1 (the position where the line L4 is connected to
the reaction column 1) according to this mode, the untreated wax
fraction may instead be introduced from the side of the reaction
column 1. When the unreacted wax fraction is introduced from the
side of the reaction column 1, the position where the line L4 is
connected to the reaction column 1 is preferably upstream from the
upstream end of the hydrocracking catalyst layer 2.
[0042] Finally, although the hydrocracking catalyst layer 2 has a
single-layer structure according to this mode, different
hydrocracking catalyst layers may be laminated to form a multilayer
structure instead.
EXAMPLES
[0043] The present invention will now be explained in greater
detail based on examples and comparative examples, with the
understanding that these examples are in no way limitative on the
invention.
Example 1
[0044] A carrier composed of cylinders of size .phi.1.5 mm and
length approximately 3 mm were formed using USY-zeolite with a mean
particle size of 0.82 .mu.m (silica/alumina molar ratio: 37),
alumina-boria (alumina/boria weight ratio: 5.6) and an alumina
binder (USY-zeolite/alumina-boria/alumina binder=Apr. 56, 1940
(weight ratio)). A platinic chloride aqueous solution was
impregnated into the carrier, for loading of platinum to 0.6% by
mass with respect to the carrier. This was dried and fired to
obtain a hydrocracking catalyst.
[0045] Next, 300 ml of the obtained hydrogenation catalyst was
packed into the reaction column 1 of a fixed bed reactor such as
shown in FIG. 1 to form a hydrocracking catalyst layer 2, and the
reactor was used for the bottom recycling experiment described
below.
[0046] First, the hydrocracking catalyst was subjected to reduction
treatment at 345.degree. C. for 4 hours under a hydrogen stream,
and then the crude wax alone was subjected to hydrocracking. FT wax
(C21-80, normal paraffin content: 95% by mass) was used as the
crude wax. As the hydrocracking reaction conditions, the liquid
space velocity of the crude wax was 2.0 h.sup.-1 (crude wax liquid
flow rate: 600 ml/h) with respect to the total amount of
hydrocracking catalyst, the hydrogen partial pressure was 3 MPa and
the hydrogen/oil ratio was 570 NL/L, while the reaction temperature
was set for a conversion ratio of 55% by mass as defined by formula
(1). The reaction temperature was set to 292.degree. C.
[0047] Upon confirming stabilization of catalytic activity after
the start of hydrocracking of the crude wax, a conversion ratio of
55% by mass as defined by formula (1) above was maintained for 50
days. The treated oil obtained during this period was distilled
with a distilling apparatus 3 (precision distilling apparatus), for
separation of the light fraction with a boiling point of below
360.degree. C. and the untreated wax with a boiling point of
360.degree. C. and above.
[0048] Next, the untreated wax fraction with a boiling point of
360.degree. C. and above was transported to the line L4, the
untreated wax fraction and crude wax were combined to an untreated
wax content of 45% by mass based on the total weight of the
untreated wax fraction and crude wax, and this mixture was used as
the starting material for hydrocracking. The reaction temperature,
set for a conversion ratio of 55% by mass as defined by formula (1)
above, was 290.degree. C. The other reaction conditions were the
same as for hydrocracking of FT wax alone.
[0049] After 30 minutes of the bottom recycling experiment, the
treated product oil was analyzed by gas chromatography to determine
the proportion of the heart-cut fraction with a boiling point of
between 145.degree. C. and 360.degree. C. in the light fraction
with a boiling point of below 360.degree. C. (hereinafter referred
to as "heart-cut fraction selectivity"), and the normal paraffin
and aromatic compound contents in the heart-cut fraction. The
results are shown in Table 1.
Example 2
[0050] A bottom recycling experiment was conducted in the same
manner as Example 1, except that the conversion ratio represented
by formula (1) above was 75% by mass for the hydrocracking of crude
wax alone, the conversion ratio represented by general formula (1)
for hydrocracking of the crude wax and untreated wax fraction was
75% by mass, and the untreated wax content of the mixture was 25%
by mass. The reaction temperature for hydrocracking of the mixture
of the crude wax and untreated wax fraction was 299.degree. C. The
heart-cut fraction selectivity obtained by chromatographic analysis
of the treated product oil and the normal paraffin and aromatic
compound contents of the heart-cut fraction are listed in Table
1.
Example 3
[0051] A hydrocracking catalyst was prepared in the same manner as
Example 1, except that USY-zeolite with a mean particle size of
0.42 .mu.m (silica/alumina molar ratio: 37) was used instead of the
USY-zeolite with a mean particle size of 0.82 .mu.m. A bottom
recycling experiment was then conducted in the same manner as
Example 1, except for using this hydrocracking catalyst. The
reaction temperature for hydrocracking of the crude wax and
untreated wax fraction was 296.degree. C. The heart-cut fraction
selectivity obtained by chromatographic analysis of the treated
product oil and the normal paraffin and aromatic compound contents
of the heart-cut fraction are listed in Table 1.
Example 4
[0052] A hydrocracking catalyst was prepared in the same manner as
Example 1, except that the USY-zeolite content was changed from 4%
by mass to 2% by mass. A bottom recycling experiment was then
conducted in the same manner as Example 1, except for using this
hydrocracking catalyst. The reaction temperature for hydrocracking
of the crude wax and untreated wax fraction was 318.degree. C. The
heart-cut fraction selectivity obtained by chromatographic analysis
of the treated product oil and the normal paraffin and aromatic
compound contents of the heart-cut fraction are listed in Table
1.
Example 5
[0053] A bottom recycling experiment was conducted in the same
manner as Example 1, except that the wax used (normal paraffin
content: 76% by mass) was a mixture of FT wax as the crude wax and
a petroleum-based paraffin wax in a weight ratio of 60:40. The
reaction temperature for hydrocracking of the crude wax and
untreated wax fraction was 326.degree. C. The heart-cut fraction
selectivity obtained by chromatographic analysis of the treated
product oil and the normal paraffin and aromatic compound contents
of the heart-cut fraction are listed in Table 1.
Example 6
[0054] A bottom recycling experiment was conducted in the same
manner as Example 1, except that the untreated wax was not mixed
with the crude FT wax, and the position of connection of the
reaction column line 1 with the line L4 was switched to a position
at the side of the reaction column 1 at 3 L/5 from the upstream end
of the hydrocracking catalyst layer 2 (where L represents the
distance from the upstream end to the downstream end of the
hydrocracking catalyst layer 2). The reaction temperature for
hydrocracking of the crude wax and untreated wax fraction was
292.degree. C. The heart-cut fraction selectivity obtained by
chromatographic analysis of the treated product oil and the normal
paraffin and aromatic compound contents of the heart-cut fraction
are listed in Table 1.
Comparative Example 1
[0055] A bottom recycling experiment was conducted in the same
manner as Example 1, except that the conversion ratio represented
by formula (1) above was 40% by mass for the hydrocracking of crude
wax alone, the conversion ratio represented by general formula (1)
for hydrocracking of the crude wax and untreated wax fraction was
60% by mass, and the untreated wax content of the mixture was 40%
by mass. The reaction temperature for hydrocracking of the mixture
of the crude wax and untreated wax fraction was 274.degree. C. The
heart-cut fraction selectivity obtained by chromatographic analysis
of the treated product oil and the normal paraffin and aromatic
compound contents of the heart-cut fraction are listed in Table
1.
Comparative Example 2
[0056] Hydrocracking of wax was carried out in the same manner as
Example 1, except that the conversion ratio represented by formula
(1) above was 95% by mass for the hydrocracking of crude wax alone,
the conversion ratio represented by general formula (1) for
hydrocracking of the crude wax and untreated wax fraction was 95%
by mass, and the untreated wax content of the mixture was 5% by
mass. The reaction temperature for hydrocracking of the mixture of
the crude wax and untreated wax fraction was 312.degree. C. The
heart-cut fraction selectivity obtained by chromatographic analysis
of the treated product oil and the normal paraffin and aromatic
compound contents of the heart-cut fraction are listed in Table
1.
TABLE-US-00001 TABLE 1 Heart-cut Normal paraffin Aromatic compound
fraction content of content of selectivity heart-cut fraction
heart-cut fraction (% by mass) (% by mass) (% by mass) Example 1
82.4 19.6 0 Example 2 80.5 13.8 0 Example 3 81.4 13.5 0 Example 4
82.5 19.1 0 Example 5 80.1 13.1 0 Example 6 83.0 19.4 0 Comp. Ex. 1
82.5 41.6 0 Comp. Ex. 2 56.8 12.9 0
[0057] As shown in Table 1, it was confirmed that Examples 1-6 had
high heart-cut fraction selectivity and low normal paraffin
contents in the heart-cut fraction, thus demonstrating that it is
possible to simultaneously achieve increased heart-cut fraction
yield and reduced normal paraffin content in the heart-cut
fraction. Furthermore, no aromatic compounds were detected in the
heart-cut fraction in Examples 1-6.
INDUSTRIAL APPLICABILITY
[0058] The hydrocracking method of wax and fuel base manufacturing
process of the invention can simultaneously achieve both an
increased heart-cut fraction yield (as the target product of the
hydrocracking) and a reduced normal paraffin content in the
heart-cut fraction, when untreated wax is subjected to bottom
recycling, and is thus useful for producing of
environmentally-friendly, clean liquid fuel.
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