Process for producing a liquefied coal oil and a catalyst for the process

A process for producing a liquefied coal oil by a two step hydrogenation reaction of coal, which comprises subjecting coal to a first hydrogenation and subjecting at least a part of the reaction product of the first hydrogenation to a second hydrogenation, wherein the second hydrogenation is conducted in the presence of an alkali metal compound and/or an alkaline earth metal compound and a catalyst carrying a metal of Group VI-A and a metal of Group VIII of the Periodic Table.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The present invention relates to a process for producing a liquefied coal 
oil by a two step hydrogenation reaction of coal, and a catalyst useful 
for the second hydrogenation reaction. More particularly, the present 
invention relates to the hydrogenation treatment of a liquefied product of 
coal by a catalyst composed of a carrier such as alumina or silica 
alumina, and a metal of Group VI-A and a metal of Group VIII of the 
Periodic Table supported thereon, wherein an alkali metal compound and/or 
an alkaline earth metal compound is incorporated to the catalyst. 
It is well known that a catalyst wherein a metal of Group VI-A of the 
Periodic Table such as molybdenum and a metal of Group VIII such as cobalt 
or nickel are supported on a carrier such as alumina, is catalytically 
effective for the hydrogenation treatment of a reaction product obtained 
by the first hydrogenation reaction of a coal such as bituminous coal, 
sub-bituminous coal, brown coal or lignite by e.g. hydrogenolysis or 
solvert extraction. 
However, such hydrogenation reaction products, particularly the high 
boiling point fractions having boiling points of at least 400.degree. C., 
contain substantial amounts of highly condensed aromatic hydrocarbons or 
aromatic compounds containing hetero-atoms such as nitrogen or sulfur in 
their molecules, which cause deactivation of the catalyst. In the 
hydrogenation treatment of such first hydrogenation reaction products, 
there used to be difficulties such as deactivation of the catalyst due to 
the formation of coke on the catalyst or clogging of a catalytic bed due 
to coking which takes place in the catalytic bed in the case of a 
continuous hydrogenation treatment in a fixed-bed type reactor. 
The present inventors have conducted extensive researches to develop a 
process and a catalyst which are highly effective for the hydrogenation 
treatment of the first hydrogenation reaction product in a two step 
hydrogenation reaction of coal and which do not bring about the formation 
of coke on the catalyst. As a result, it has been found that when an 
alkali metal compound or an alkaline earth metal compound is used in 
combination with the catalyst carrying a metal of Group VI-A and a metal 
of Group VIII of the Periodic Table, the catalyst exhibits a superior 
catalyst activity, whereby the coking is substantially suppressed and the 
deterioration of the catalytic activity in the continuous hydrogenation 
treatment reaction is prevented to a substantial extent. The present 
invention has been accomplished based on these discoveries. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a superior process for 
the production of a liquefied coal oil by the two step hydrogenation 
reaction of coal and to provide a catalyst for the second hydrogenation 
reaction, which is capable of providing a high catalytic activity for a 
long period of time, while suppressing the coking on the catalyst and 
preventing the deterioration of the catalytic activity. 
Such an object can be attained by a catalyst for such a second 
hydrogenation reaction which carries a metal of Group VI-A and a metal of 
Group VIII of the Periodic Table and which contains an alkali metal 
compound and/or an alkaline earth metal compound. 
The present invention also provides a process for producing a liquefied 
coal oil by a two step hydrogenation reaction of coal, which comprises 
subjecting coal to a first hydrogenation and subjecting at least a part of 
the reaction product of the first hydrogenation to a second hydrogenation, 
wherein the second hydrogenation is conducted in the presence of the 
above-mentioned catalyst.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Now, the present invention will described in detail with reference to the 
preferred embodiments. 
The catalyst to be used in the present invention, may be the one wherein a 
Group VI-A metal and a Group VIII metal are supported on a carrier such as 
commercial alumina or silica-alumina or on a solid acid such as alumina 
prepared from boehmite. As the Group VI-A metal, there may be mentioned 
molybdenum or tungsten, and as the Group VIII metal, cobalt or nickel is 
particularly preferred. As the starting material containing such a metal, 
there may be mentioned cobalt nitrate, nickel nitrate, ammonium molybdate 
or ammonium tungstate. These compounds are supported on the carrier and 
preferably fired. With respect to the amounts of these metal components 
supported on the carrier, the amount of the Group VI-A metal is from 1 to 
50% by weight, preferably from 5 to 20% by weight, in the catalyst. The 
amount of the Group VIII metal is from 0.1 to 20% by weight, preferably 
from 1 to 10% by weight, in the catalyst. Such a catalyst is usually 
sulfided by e.g. elemental sulfur, hydrogen sulfide or carbon disulfide, 
prior to its use. The amount of the sulfur component to be used, is 
preferably at a level of the stoichiometric amount reactive as sulfur with 
the total metal components. 
As the alkali metal or alkaline earth metal compounds, there may be 
employed hydroxides such as sodium hydroxide, potassium hydroxide or 
calcium hydroxide; halides such as sodium chloride, potassium chloride, 
sodium iodide or calcium iodide; mineral acid salts such as carbonates, 
nitrates, nitrites or sulfates; organic acid salts such as acetates or 
oxalates; oxides; or alkali metal or alkaline earth metal compounds such 
as alcoholates. 
The amount of the alkali metal compound and for the alkaline earth metal 
compound is from 0.001 to 5% by weight as the alkali metal element or the 
alkaline earth metal element in the catalyst. 
The alkali metal compound or the alkaline earth metal compound may be 
present in any form in the reaction system. However, it is most preferred 
that a catalyst carrying the Group VI-A metal and the Group VIII metal is 
treated with the alkali metal or alkaline earth metal prior to sulfiding 
the catalyst. As the treating method, there may be employed a method 
wherein a catalyst is immersed in an aqueous solution or an alcohol 
solution in which an alkali metal compound or an alkaline earth metal 
compound is dissolved, and then dried. In this case, the catalyst may be 
fired again. However, the catalyst may be used without such firing. 
Otherwise, there may be employed a method wherein an alkali metal compound 
or an alkaline earth metal compound is incorporated during the production 
of the catalyst, or a method in which the alkali metal compound or the 
alkaline earth metal compound may be added to the reaction system. 
The property of the catalyst, particularly the pore distribution, 
influences the hydrogenation of the first hydrogenation reaction product. 
Accordingly, it is particularly preferred to employ a catalyst which has a 
total pore volume of at least 0.6 cc/g as measured by a mercury 
compression method and a pore distribution such that the pore volume of 
pores having radii of at least 100 .ANG. is from 20 to 70% of the total 
pore volume, and the pore volume of pores having radii of from 37.5 to 100 
.ANG. is from 30 to 80% of the total pore volume. With such a specified 
property, the catalytic activity on the heavy hydrocarbon compounds 
contained in the first hydrogenation reaction product increases, and the 
activity on the light components decreases, whereby it is possible to 
effectively avoid such a problem that the formed liquefied oil is further 
decomposed to gas and the yield of the liquefied oil decreases. 
There is no particular restriction to the first hydrogenation reaction 
product to which the catalyst of the present invention is applied. 
However, it is preferred to use as the first hydrogenation reaction 
product, for instance, a liquefied product of coal obtained by the 
hydrogenolysis of a coal such as brown coal, bituminous coal or 
sub-bituminous coal together with a hydrocarbon solvent in the presence or 
absence of a catalyst under a hydrogen pressure of from 100 to 300 
kg/cm.sup.2 G at a temperature of from 350.degree. to 500.degree. C. for 
0.1 to 2 hours, followed by solvent extraction. The liquefied product of 
coal as the first hydrogenation reaction product, may be liquid or solid 
at room temperature. Particularly preferred is a solid solvent-refined 
coal. 
The second hydrogenation reaction of the first hydrogenation reaction 
product may be conducted by a known method under known conditions in a 
batch system, a boiled-bed system or a fixed-bed system. For instance, it 
is possible to efficiently hydrogenate and decompose the first 
hydrogenation reaction product and obtain light fractions by conducting 
the second hydrogenation reaction under a hydrogen pressure of from 10 to 
300 kg/cm.sup.2 G at a reaction temperature of from 250.degree. to 
500.degree. C., at a liquid space velocity of the first hydrogenation 
reaction product of from 0 to 5 hr.sup.-1 at a volume ratio of hydrogen to 
the first hydrogenation reaction product of from 500 to 2000. 
Further, the two step hydrogenation reaction of coal according to the 
present invention, may be modified by adding a preliminarily treatment 
before or after, or inbetween the hydrogenation reactions, or by dividing 
each hydrogenation reaction into a plurality of stages. 
For instance, in the case where the second hydrogenation reaction is 
applied to a solvent-refined coal, the second hydrogenation reaction may 
be further divided into a first stage and a second stage, and high boiling 
point fractions from the first stage are supplied to the second stage. In 
this case, the above-mentioned catalyst containing an alkali metal and/or 
alkaline earth metal, is used at least in the first stage wherein the 
first reaction product itself is hydrogenated. Whereas in the second 
stage, there will be no substantial problem of the formation of coke 
whether or not the catalyst used, contains an alkali metal or an alkaline 
earth metal. In the second stage, it is preferred to use a catalyst 
wherein the pore volume of pores having pore radii of at most 100 .ANG. is 
large, as the catalyst suitable for hydrogenating a partially hydrogenated 
solvent-refined coal. Specifically, as such a catalyst, there may be 
mentioned a catalyst which has a total pore volume of at least 0.4 cc/g as 
measured by a mercury compression method and a pore distribution such that 
the pore volume of pores having radii of at least 100 .ANG. is from 0 to 
20% of the total pore volume and the pore volume of pores having radii of 
from 37.5 to 100 .ANG. is from 80 to 100% of the total pore volume. 
As described in the foregoing, by employing the process and the catalyst of 
the present invention for the hydrogenolysis of the first hydrogenation 
reaction product in the two step hydrogenation reaction cf coal, it is 
possible to minimize the precipitation of a carbonaceous substance on the 
catalyst, to prolong the effective life of the catalyst and to maintain a 
high catalytic activity for an extended period of time. Thus, the present 
invention is extremely valuable from the industrial point of view. 
Now, the present invention will be described in further detail with 
reference to Examples. However, it should be understood that the present 
invention is by no means restricted by these specific Examples. 
EXAMPLE 1 
Into a solution prepared by dissolving 9.2 g of ammonium paramolybdate 
[(NH.sub.4).sub.6 Mo.sub.7 O.sub.24.H.sub.2 O] and 4.8 g of nickel nitrate 
[Ni(NO.sub.3).sub.2.6H.sub.2 O] in an aqueous ammonia solution and 
bringing the total volume to 40 ml, 20 g of an alumina carrier prepared 
from boehmite (surface area: 216 m.sup.2 /g, pore volume: 1.00 cc/g, pore 
volume of pores having radii of at least 100 .ANG.: 0.66 cc/g, pore volume 
of pores having radii of from 37.5 to 100 .ANG.: 0.34 cc/g, the same 
carrier being used also hereinafter) was immersed for 12 hours, and after 
the removal of the solution by filtration, dried at 120.degree. C. for 12 
hours, and then fired at 600.degree. C. for 3 hours to obtain a catalyst. 
The Ni content was 2.4% by weight, and the Mo content was 12.7% by weight. 
In a solution prepared by dissolving 0.02 g of sodium hydroxide in 100 ml 
of methanol, 5 g of this catalyst was immersed for 12 hours, and then 
vacuum-dried. The catalyst thus treated was fed into an autoclave having 
an internal capacity of 300 ml together with 80 g of a liquefied coal oil 
(boiling point: 300.degree.-420.degree. C./760 mmHg) and 0.05 g of sulfur, 
and the hydrogenation treatment was conducted under a hydrogen pressure of 
100 kg/cm.sup.2 G at a reaction temperature of 450.degree. C. for a 
reaction time of 60 minutes. Then, reaction mixture was filtered to remove 
the catalyst, and the filtrate was distilled. The conversion was 
calculated in accordance with the following formula I and shown in Table 
1. Further, the catalyst recovered by the filtration, was thoroughly 
washed with tetrahydrofuran, dried and then subjected to an elemental 
analysis, whereby it was found that the amount of the deposited 
carbonaceous substance has as shown in Table 1. 
##EQU1## 
EXAMPLE 2 
The hydrogenation treatment was conducted in the same manner as in Example 
1 except that the catalyst used, was prepared in such a manner that 5 g of 
the catalyst composed of nickel and molybdenum supported on the alumina 
carrier (Ni content: 2.4% by weight, Mo content: 2.7% by weight) was 
immersed in a solution prepared by dissolving 0.10 g sodium hydroxide in 
100 ml of methanol, for 12 hours, and then vacuum dried. The results are 
shown in Table 1. 
COMATIVE EXAMPLE 1 
The hydrogenation treatment was conducted in the same manner as in Example 
1 except that 5 g of the catalyst composed of nickel and molybdenum 
supported on the alumina carrier as used in Example 1 or 2, was used 
without any further treatment, together with 0.05 g of sulfur. The results 
are shown in Table 1. 
TABLE 1 
______________________________________ 
Amount of carbon deposition 
Conversion 
on the catalyst* 
______________________________________ 
Example 1 12.1% 2.3% 
Example 2 10.0% 2.4% 
Comparative 
11.4% 4.8% 
Example 1 
______________________________________ 
*% by weight based on the recovered catalyst 
EXAMPLE 3 
In a solution prepared by dissolving 0.2 g of sodium hydroxide in 100 ml of 
methanol, 10 g of a catalyst composed of nickel and molybdenum supported 
on the alumina carrier (Ni content: 3.4% by weight, Mo content: 8.0% by 
weight) was immersed in 12 hours and then vacuum-dried. The catalyst thus 
treated was fed into an autoclave having an internal capacity of 300 ml, 
together with 40 g of a solvent-refined coal (boiling points: at least 
420.degree. C./760 mmHg) and 0.72 g of sulfur. The hydrogenation treatment 
was conducted under a hydrogen pressure of 100 kg/cm.sup.2 G at a reaction 
temperature of 420.degree. C. for a reaction time of 120 minutes, and then 
the reaction mixture was distilled. The conversion was calculated. The 
results are shown in Table 2. Further, the recovered catalyst was 
thoroughly washed with tetrahydrofuran, dried and subjected to an 
elemental analysis, whereby the carbonaceous substance precipitated on the 
catalyst was quantitatively analyzed. This result is also shown in Table 
2. 
COMATIVE EXAMPLE 2 
The hydrogenation treatment was conducted in the same manner as in Example 
3 except that 10 g of the catalyst composed of nickel and molybdenum 
supported on the alumina carrier (Ni content: 3.4% by weight, Mo content: 
8.0% by weight) was used without any further treatment. The results are 
shown in Table 2. 
TABLE 2 
______________________________________ 
Amount of carbon deposition 
Conversion 
on the catalyst* 
______________________________________ 
Example 3 48% 6.9% 
Comparative 
38% 9.0% 
Example 2 
______________________________________ 
*% by weight based on the recovered catalyst 
EXAMPLE 4 
Into a solution prepared by dissolving 6.6 g of ammonium paramolybdate in 
an aqueous ammonia solution and bringing the total volume to 40 ml, 20 g 
of the same alumina carrier as used in Example 1, was immersed for 12 
hours, and after the removal of the solution by filtration, dried at 
120.degree. C. for 12 hours and then fired at 600.degree. C. for 3 hours. 
Further, in a solution prepared by dissolving 4.9 g of cobalt nitrate 
[Co(NO.sub.3).sub.2.6H.sub.2 O] in water and bringing the total volume to 
40 ml, the molybdenum-alumina carrier fired product was immersed for 12 
hours, and then dried and fired under the safe conditions as in the 
treatment for supporting molybdenum on the carrier, whereby a 
cobalt-molybdenum-alumina catalyst was obtained. The Co content was 2.5% 
by weight and the Mo content was 9.0% by weight. 
In a solution prepared by dissolving 0.2 g of sodium hydroxide in 100 ml of 
methanol, 10 g of this catalyst was immersed for 12 hours, and then 
vacuum-dried for 12 hours. Then, 10 g of the catalyst thus prepared, was 
fed into a 300 ml autoclave together with 0.72 g of sulfur, and the 
solvent-refined coal was subjected to hydrogenation treatment under the 
same conditions as in Example 3. The reaction mixture was distilled, and 
the conversion was obtained. The results are shown in Table 3. 
COMATIVE EXAMPLE 3 
The hydrogenation treatment was conducted in the same manner as in Example 
4 except that 10 g of the catalyst composed of cobalt and molybdenum 
supported on the alumina carrier, as used in Example 4, was used without 
any further treatment. 
TABLE 3 
______________________________________ 
Amount of carbon deposition 
Conversion 
on the catalyst* 
______________________________________ 
Example 4 41% 5.4% 
Comparative 
39% 7.5% 
Example 3 
______________________________________ 
*% by weight based on the recovered catalyst 
EXAMPLE 5 
A catalyst composed of nickel and molybdenum supported on alumina (Ni 
content: 3.4% by weight, Mo content: 8.0% by weight) was immersed in a 
solution prepared by dissolving 0.02 part by weight of sodium hydroxide, 
relative to the catalyst, in methanol, for 12 hours, and then 
vacuum-dried. Then, this catalyst was packed in a fixed bed reaction 
apparatus. 
A solvent-refined coal (boiling point: at least 420.degree. C./760 mmHg) 
and a liquefied coal oil (boiling point: 250-420.degree. C./760 mmHg) as a 
solvent, were mixed in a weight ratio of 1:2. The mixture was passed 
through the fixed bed reaction apparatus packed with the above-mentioned 
catalyst, at a reaction temperature of 400.degree. C. under a hydrogen 
pressure of 100 kg/cm.sup.2 G and a liquid space velocity of 0.5 
hr.sup.-1. 
This test was conducted continuously for 500 hours. The conversion was 
shown by the catalytic performance curve (a) in FIG. 1. 
Further, the catalyst recovered after the continuous test, was thoroughly 
washed with tetrahydrofuran, then dried and subjected to an elemental 
analysis, whereby it was found that 13.1% by weight, based on the 
recovered catalyst, of carbonaceous substance was deposited on the 
catalyst. 
COMATIVE EXAMPLE 4 
The continuous hydrogenation treatment test was conducted in the same 
manner as in Example 5 except that the catalyst composed of nickel and 
molybdenum supported on alumina was used without the alkali metal or 
alkaline earth metal treatment. 
The conversion was shown by the catalytic performance curve (b) in FIG. 1. 
Further, it was found that 16.1% by weight, based on the recovered 
catalyst, of carbonaceous substance was deposited on the catalyst. 
EXAMPLE 6 
A catalyst was prepared in the same manner as described in Example 3, 
except that calcium acetate was employed in place of sodium hydroxide. 
A hydrogenation treatment was also conducted in the same manner as 
described in Example 3. The results obtained are shown in Table 4 below. 
EXAMPLE 7 
A catalyst was prepared in the same manner as described in Example 4, 
except that calcium acetate was employed instead of sodium hydroxide. 
A hydrogenation treatment was conducted in the same manner as described in 
Example 4. The results are shown in Table 4. 
TABLE 4 
______________________________________ 
Amount of carbon 
deposition of the 
Catalyst Conversion catalyst* 
______________________________________ 
Example 6 
Ca--Ni--Mo 46% 6.1% 
(Ca 2%) 
Example 7 
Ca--Co--Mo 39% 4.8% 
(Ca 2%) 
______________________________________ 
*% by weight based on the recovered catalyst.