AU720389B2 - Process of coal liquefaction - Google Patents

Description

ML

Lb P/00/011 Regulation 3.2

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION ae a a.

at. a FOR A STANDARD PATENT

ORIGINAL

We, KOBE STEEL LTD, of 3-18, Wakinohama-cho 1-chomne, Chuo-ku, Kobe-shi, Hyogo-ken, Japan, MITSUBISHI CHEMICAL CORPORATION, of 5-2 Marunouchi 2chorne, Chiyoda-ku, Tokyo, Japan, IDEMITSU KOSAN CO. LTD, of 1-1 Marunouchi 3-chorne, Chiyoda-ku, Tokyo, Japan, COSMO OIL, COMPANY LTD, of 1 Shibaura I1-chomne, Minato-ku, Tokyo 105-8528, Japan and NISSHO IWAI CORPORATION, of 5-8, Imiabashi 2-chorne, Chuo-ku, Osaka 541-0042, TO BE COMPLETED BY APPLICANT Name of Applicant: Actual Inventors: Address for Service: Invention Title: NIPPON BROWN COAL LIQUEFACTION CO., LTD- Takao KANEKO; Kazuharu TAZAWA; Toru KOYAMA; Kouichi SATOU CALLINAN LAWRIE, 711 High Street, Kew, 3101, Victoria, Australia "PROCESS OF COAL LIQUEFACTION" The following statement is a full description of this invention, including the best method of performing it known to me:- INVENTION TITLE Process of Coal Liquefaction BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a process of coal liquefaction and more particularly belongs to the technical field about a process of coal liquefaction including a hydrogenation step in which coal is hydrogenated under a presence of catalyst.

Description of the Related Art The recent resources and energy situation urgently require the development of a liquid fuel as a substitute for petroleum. In view of abundant coal reserves in particular, it is important to establish techniques of *oo.

efficiently liquefying coal to obtain a liquid fuel. Due to this fact, there have been proposed a variety of S"processes of coal liquefaction. A typical process of coal liquefaction includes mixing dry pulverized coal with a solvent to give a slurry mixture, adding hydrogen gas to the mixture under high temperature and high pressure conditions, and performing hydrogenation so as to liquefy it.

In performing the hydrogenation reaction (liquefaction reaction), it is sometimes applied that catalyst is not added in response to a specific type of coal of raw material but catalyst substance contained in coal is utilized. However, there is generally employed a process in which the catalyst is added to the slurry mixture in order to improve the efficiency of the hydrogenation reaction for use with the hydrogenation reaction, and coal is hydrogenated in the co-presence of a catalyst and a solvent.

As catalyst for use in improving the efficiency of this hydrogenation reaction, i.e. as catalyst for promoting liquefying reaction of coal (hereinafter called as "catalyst for coal liquefaction"), although there have been known in the prior art to provide various kinds of I. molybdenum-based catalysts or catalysts such as zinc chloride, tin chloride or iron sulfide, sulfate of iron, iron oxide, iron hydroxide, red mud, iron ores or the like, *o all these catalysts have not been satisfactory as the catalysts for coal liquefaction and each of them has shown a problem, respectively.

That is, although the catalyst for coal liquefaction requires that fundamentally the catalyst is activated as it is it is superior in catalyst function to improve the efficiency of hydrogenation reaction), that the catalyst may easily be available in less-expensive manner in view of economical criterion of coal liquefaction and that no trouble occurs in operation of the coal liquefaction, the molybdenum-based catalyst in the aforesaid categories of catalyst is quite expensive and has a problem related to resources, and further the catalysts of chlorides group such as zinc chloride may easily corrode the device. In addition, although the catalysts of iron sulfide, iron sulfate, iron oxide, iron chloride, red mud and iron ores or the like are less-expensive, they show a problem that no satisfactory activation (hereinafter called as a "catalyst activation") is attained in the catalyst.

In these catalysts, although the iron ore has no sufficient activation as catalyst, it has some advantages that its price is less-expensive and a relative large amount of catalyst may be available in a relative easy manner, resulting in that this catalyst is one of the highly practical catalysts for coal liquefaction at *present. Due to this fact, there have been provided many proposals for improving the activation of iron ore acting as the catalysts for coal liquefaction. Up to now, the present inventors have provided several proposals of process of coal liquefaction having a feature that pulverized iron ore having a mean particle diameter of :i"~pm or less mechanically pulverized in circulating solvent for coal liquefaction (coal liquefaction solvent).

Advantages of such a process as described above consist in the facts that cohesion aggregation of the catalyst particles is hardly produced in the solvent, the efficiency of contact between the catalyst and coal can be improved because the catalyst has a superior dispersion characteristic, resulting in that the activation of the catalyst is improved and the yield efficiency for the oil (i I e can also be improved with a less amount of application of the catalyst.

However, it has become apparent that some of the iron ores applied as the catalysts are quite hard and so the device for pulverizing catalysts may easily be worn out, for example, balls in the ball mill for use in pulverizing catalysts may also be easily worn out, resulting in that they are disadvantage in view of their economical state.

in addition, although it is known that limonite selected from the iron ores applied as catalysts has a relative high activity, it is not possible to say that the prior art catalyst of the iron ore has a sufficient activity of the catalyst in view of its economic characteristic of coal liquefaction and further, there are some fluctuations in activity of catalyst in accordance with a site of production and an ore region of the iron ore and so in order to perform an economical effective reaction of coal liquefaction, it is desired to develop a process of coal liquefaction capable of attaining a high activity of S"catalyst and improving a yield efficiency of the liquefied oil.

DETAILED DESCRIPTION OF THE INVENTION The present invention has been invented in view of the foregoing situations and its object is to provide a process of coal liquefaction in which iron ore to be used as catalyst has a more superior pulverizing characteristic, a less wearing of equipment for pulverizing catalyst as -4compared with those of the prior art process of coal liquefaction and further it has a high activity of catalyst and can improve a yield efficiency of the liquefied oil.

In order to accomplish the aforesaid object, the process of coal liquefaction of the present invention is carried out by the processes of coal liquefaction described in Claims 1 to 3 and each of these processes has the following constitution. That is, the process of coal liquefaction described in Claim 1 is a process of coal liquefaction including a hydrogenation step in which iron ore mechanically pulverized in coal liquefaction solvent to have a mean particle diameter of 10 tim or less is applied as catalyst and coal is hydrogenated under co-presence of solvent and catalyst characterized in that said iron ore is limonite and concurrently a molar ratio between intrinsic moisture and iron atom in said limonite is 0.4 or more (the first invention).

A process of coal liquefaction described in Claim 2 is process of coal liquefaction described in Claim 2 is a process of coal liquefaction described in Claim 1, wherein said limonite is limonite in which iron oxide is not substantially contained (the second invention).

A process of coal liquefaction described in Claim 3 is a process of coal liquefaction according to Claim 1 or Claim 2, wherein either elemental sulfur or sulfur compound is present together with said coal, solvent and catalyst (the third invention).

This invention relates to a process of coal liquefaction, wherein this process is carried out as follows, for example.

Limonite with a molar ratio between intrinsic moisture and iron atom being 0.4 or more is mechanically pulverized in coal liquefaction solvent by a catalyst pulverizing equipment such as a ball mill or the like to cause its size to be a mean particle diameter less than pmn. Then, solvent is added to coal, the aforesaid pulverized limonite is added as catalyst so as to attain a slurry mixture. Then, hydrogen gas at a high temperature and under a high pressure is added to the slurry mixture to hydrogenate coal.

As described above, the process of coal liquefaction according to the present invention is a process of coal a.

liquefaction in which iron ore mechanically pulverized in the coal liquefaction solvent with a mean particle diameter being 10 Jn or less is applied as a catalyst and including :i a hydrogenation step where coal is hydrogenated under cooa S"presence of solvent and catalyst characterized in that the aforesaid iron ore is limonite and a molar ratio between intrinsic moisture and iron atom in the limonite is 0.4 or more (the first invention).

That is, the process of coal liquefaction in accordance with the present invention is operated such that when coal is hydrogenated under co-presence of solvent and catalyst, limonite mechanically pulverized in the coal liquefaction solvent (coal liquefaction circulating -6solvent) with a mean particle diameter being 10 pm or less and with a molar ratio between intrinsic moisture and iron atom being 0.4 or more is used as catalyst. In other words, the limonite with a molar ratio between intrinsic moisture and iron atom being 0.4 or more is mechanically pulverized in the coal liquefaction circulating solvent to attain a mean particle diameter of 10 pm or less and this limonite is used as catalyst for coal liquefaction.

As described above, the process of coal liquefaction according to the present invention basically belongs to such a process of coal liquefaction as one using iron ore as coal liquefaction catalyst, though limonite is used as *this iron ore. This is due to the fact that limonite in the iron ore has a relative high activity of catalyst.

When limonite is used as the coal liquefaction catalyst, limonite with a mean particle diameter being pm or less is used. This means that application of limonite having a particle diameter over the mean particle diameter of 10 pm may cause a contact efficiency between the S""catalyst and coal to become low and activity of the catalyst to be decreased and insufficient value is attained due to the low effective area of the catalyst (an outer surface area of catalyst particle per catalyst weight). In order to increase the actual effective surface area of such a catalyst as above and increase the activity of the catalyst, it is preferable that the mean particle diameter is 10 m or less and in view of such a fact as above, it is desirable to keep it less than 5 pmn and more particularly 1 Lm or less.

Although limonite with its mean particle diameter being 10 pm or less can be attained by pulverizing limonite, this pulverizing process is not carried out in dry form, but performed in the coal liquefaction solvent.

That is, limonite mechanically pulverized in the coal liquefaction solvent (its mean particle diameter: 10 pmn or less) is used as catalyst. This is due to the facts that the pulverizing process is more efficiently carried out in 0 the coal liquefaction solvent with a medium agitating type W•oo pulverizing machine or the like than that of performing a dry pulverizing operation with a gas flow type pulverizing *9*o machine or the like; the catalyst obtained by the dry pulverizing operation in the slurry mixture comprised of coal, solvent and catalyst shows a remarkable cohesion aggregation in solvent and shows a poor dispersion of catalyst; the catalyst pulverized in the coal liquefaction solvent hardly shows a cohesion aggregation in the solvent, but shows a superior dispersing characteristic of catalyst; due to this characteristic, a contact efficiency between the catalyst and the coal can be increased, resulting in that the activity of catalyst can be increased. Such effects as above are remarkably high in the case that the mean particle diameter of catalyst is 5 m or less.

In addition, it is assumed that the aforesaid limonite has a molar ratio between intrinsic moisture and iron atom more than 0.4. That is, limonite with a molar ratio between intrinsic moisture and iron atom being 0.4 or more is mechanically pulverized in the coal liquefaction circulation solvent to cause its mean particle diameter to be 10 gm or less and used as the coal liquefaction catalyst. A reason why this limonite is used consists in the facts that limonite with a molar ratio between intrinsic moisture and iron atom being 0.4 or more has a superior pulverizing characteristic, equipment for pulverizing catalyst is hardly worn out, catalyst activity is high and oil yield can be improved.

As described above, limonite with a molar ratio between intrinsic moisture and iron atom being 0.4 or more has a superior pulverizing characteristic, equipment for ,oooe pulverizing catalyst is hardly worn out, catalyst activity is high and oil yield can be improved. These facts are new acknowledgement attained by the following study and experiments.

oeo *e That is, the present inventors checked a pulverizing characteristic of each of various kinds of iron ores in the .4 coal liquefaction solvent and a degree of wear of balls in the ball mill applied in pulverizing operation. As a result, it has been found that limonite with a molar ratio between intrinsic moisture and iron atom being 0.4 or more has a superior pulverizing characteristic and the balls are less worn out.

In addition, liquefying reaction of coal was performed with application of various kinds of iron ores as catalyst and activity of catalyst was evaluated. As a result, it has -9been found that the activity of catalyst becomes high in the case that a molar ratio between intrinsic moisture and iron atom in the limonite is 0.4 or more. Additionally, a powder X-ray diffraction analysis showed that limonite having a-iron oxyhydroxide as its major substance and not showing any peak of a-iron oxide, i.e. limonite substantially not containing any iron oxide shows the highest activity of catalyst.

As described above, the catalyst activity is high in .the case that the molar ratio between intrinsic moisture eer and iron atom in the limonite is 0.4 or more and in •e oc particular, the limonite substantially not containing iron oxide shows the highest activity of catalyst. A reason why such effects may be attained will be described as follows.

As an important factor for making a high activation of catalyst, it can be said that active phase for realizing activation of catalyst is present at a lower temperature than 250C where a thermal decomposition of coal begins to occur. A chemical form of the active phase of iron compound such as iron ore is a kind of iron sulfide called as pyrrhotite, and in the case that a transformation temperature for pyrrhotite is higher than 250°C, a sufficient amount of hydrogen is not applied for radical of thermal decomposition generated between 250°C and this transformation temperature and a large amount of nondesired polycondensation substance are produced, resulting in that a yield of liquefied oil is reduced. Accordingly, it is desirable that the transformation temperature of iron compound into pyrrohtite is 250'C or less.

A transformation temperature of iron compound into pyrrohotite can be surveyed and acknowledged by the method described below.

That is, iron compound is generally processed with sulfur or sulfur compound into sulfide and also changed into iron sulfide compound. This iron sulfide compound can be classified into pyrrhotite (Fel-xS), troilite (FeS) and pyrite (FeS 2 or the like in view of its form. Their peak ;positions are different in X-ray diffraction for their 9* powder form and so their discrimination may easily be carried out. Accordingly, the iron compound to be surveyed and acknowledged is processed at a predetermined temperature into sulfide to make iron sulfide compound and then processed in powder form by an X-ray diffraction to enable a form of the iron sulfide compound to be surveyed and acknowledged. At this time, as a sulfide formation temperature is changed, a temperature where the iron compound is transformed into pyrrhotite can be acknowledged.

The present inventors studied about an action of sulfide formation of iron compound into pyrrhotite or action of catalyst of pyrrhotite by applying such a surveying and acknowledging method. As a result, the present inventors found that the catalyst action of pyrrhotite, its degree of active catalyst and the temperature where the iron compound is transformed into -11pyrrhotite are made different in reference to the type of the iron compound, and in particular, iron oxyhydroxide is processed into sulfide at a temperature lower than 250'C and transformed into pyrrhotite so as to show a high active catalyst.

Although limonite can be acknowledged as a-iron oxyhydroxide and a-iron oxide through X-ray diffraction analysis in powder form, a ratio of substance of each of airon oxyhydroxide and a-iron oxide is made different in view of production site and ore region or the like and in general limonite is expressed as Fe 2 03*nH 2 0. In addition, 6, •when limonite is heated to change substance of a-iron 2. oxyhydroxide into a-iron oxide after generating moisture and so its weight (mass) is reduced. Accordingly, the more a weight reducing amount intrinsic moisture amount) when limonite is heated, the more an inclusion amount of the substance of a-iron oxyhydroxide in limonite, and the transformation temperature into pyrrhotite is reduced and high active catalyst can be attained. Accordingly, the more the molar ratio between intrinsic moisture and iron atom in the limonite, the higher the activity of catalyst.

Studying and experiment showed that a degree of increasing in activity of catalyst as the molar ratio between intrinsic moisture and iron atom in the aforesaid limonite is increased is low at a region where such molar ratio is lower than 0.4 and in turn high at another region where such molar ratio is 0.4 or more.

-12- In the case that the intrinsic moisture in limonite shows the highest value, an amount of inclusion of a-iron oxyhydroxide in limonite shows the highest value, so that a transformation temperature into pyrrhotite shows the lowest value and the activity of catalyst shows the highest value.

As described above, limonite showing the highest amount of intrinsic moisture corresponds to limonite having as its major substance a-iron oxyhydroxide and not showing a peak of a-iron oxide in X-ray diffraction analysis, i.e.

ri limonite substantially not containing iron oxide.

r -Accordingly, limonite substantially not containing iron 9oxide shows the highest activity of catalyst.

SWith the foregoing reasons, the catalyst shows a higher activity in the case that a molar ratio between intrinsic moisture and iron atom in limonite is 0.4 or more and in particular, limonite substantially not containing iron oxide shows the highest activity of catalyst.

The present invention is completed in view of the foregoing acknowledgement and the process of coal liquefaction of the present invention is a process of coal liquefaction including a hydrogenation step carried out such that pulverized iron ore with a mean particle diameter of 10 pm or less mechanically pulverized in coal liquefaction solvent is applied as catalyst and coal is hydrogenated under co-presence of solvent and catalyst, wherein its feature consists in the fact that the aforesaid iron ore is limonite and a molar ratio between intrinsic moisture and iron atom in the aforesaid limonite is 0.4 or -13more. In accordance with the process of coal liquefaction of the present invention, it has a superior pulverizing characteristic of iron ore used as catalyst and less wear of equipment for pulverizing catalyst as compared with that of the prior'art on a process of coal liquefaction and further its catalyst may have a higher activity and the yield of liquefied oil can be improved (the first invention).

It is preferable that the aforesaid limonite is limonite substantially not containing iron oxide. Such to too limonite as above is limonite having as its major substance (Y a-iron oxyhydroxide and not showing any peak of -iron to 44 oxide in X-ray diffraction analysis and further showing the highest amount of intrinsic moisture, so that the transformation temperature into pyrrhotite shows the lowest value, resulting in that activity of catalyst indicates the highest value, and so the yield of liquefied oil can be t improved (the second invention).

In this case, a molar ratio between intrinsic moisture and iron atom in limonite substantially not containing iron oxide is 0.65. In general, although limonite has as its major substance a-iron oxyhydroxide, it is sometimes found that amorphous iron hydroxide having a chemical formula of Fe(OH) 3 is included. It is expected that a molar ratio between intrinsic moisture and iron atom in limonite in this case becomes the highest value of 1.50. Accordingly, there is an upper limit value of molar ratio between intrinsic moisture and iron atom in limonite and its value -14is 1.50. Considering this point shows that it may also be expressed that limonite having a molar ratio between intrinsic moisture and iron atom according to the first invention more than 0.4 is limonite with a molar ratio between intrinsic moisture and iron atom being 0.4 to In addition, it may also be expressed that limonite substantially not containing iron oxide according to the second invention is limonite with a molar ratio between intrinsic moisture and iron atom being 0.65 to In the present invention, limonite may act as coal 0 liquefaction catalyst under a state of its sulfide.

.e.i Accordingly, it is required at the time of hydrogenation reaction of coal that limonite is changed into sulfide. As regards this formation of sulfide, if a relative large amount of sulfur or sulfur compound is contained in coal under co-presence of limonite in slurry mixture, this formation can be produced under a reaction between this

(C

sulfur or sulfur compound. However, in order to perform a sufficient formation of sulfur of limonite, it is preferable that either elemental sulfur or sulfur compound is added to slurry mixture and placed under co-presence of limonite (the third invention). In turn, in the case that a less amount of inclusion of sulfur or sulfur compound in the raw coal is found, either elemental sulfur or sulfur compound is added as described above and set under copresence of limonite, resulting in that limonite can be sufficiently changed into sulfide (the third invention). In addition, before mixing limonite, coal and solvent, it may also be applicable as effective means that limonite is processed in advance into sulfide, limonite after processing into sulfide is mixed with coal and solvent and used as coal liquefaction catalyst.

As coals, sub-bituminous coal or bituminous coal can be applied in addition to coal of low degree of carbonization (coal with a low degree of carbonization) such as lignite or the like. These coals are usually dried to have a moisture rate of 15% or less, thereafter they are ground to have a more fine grain size than about 60 meshes uand applied to enable an advantageous liquefaction of coal to be carried out. However, the present invention is not tlimited to these materials.

A condition of hydrogenation reaction at a 'i .5 hydrogenation step is not specifically limited, but a 0O condition of producing a hydrogenation reaction is -satisfactory and normally this process is carried out under (0 conditions of a temperature of 350°C to 500"C, a partial pressure of hydrogen of 7 to 20 MPa and a reaction time of to 120 minutes and a coal liquefaction can be effectively carried out under these conditions. Although the product obtained under hydrogenation reaction may be recovered as liquefied oil after separation of solid substance such as catalysts or the like, normally the liquefied oil after separation is sent to a distillation tower and separated into some desired objective substances (heavy oil, middle oil ad light oil or the like) and recovered and concurrently a part of the heavy oil is -16circulated as circulating solvent to a slurry mixture adjusting step.

The coal liquefaction solvent is also referred to as a coal liquefaction circulating solvent. The coal liquefaction solvent (coal liquefaction circulating solvent) is meant by solvent (the second coal liquefaction circulating solvent) which is used as solvent in the slurry adjusting step (a step for attaining slurry mixture under co-presence of coal, solvent and catalyst), separated as solvent from produced substances (hydrogenated product) at (4 the hydrogenation step of coal (a step for producing hydrogenation reaction to liquefy coal) at a solvent separating step or liquefied oil separating step (a step for separating solvent and obtaining it under separating ,i operation such as distillation from the hydrogenated product or step for separating liquefied oils), thereafter circulated and supplied to the slurry adjusting step and (4 used as solvent, subsequently these operations are Srepeated, the solvent is separated into solvent (the first coal liquefaction circulating solvent) circulated between the slurry adjusting step and the solvent separating step or liquefied oil separating step and solvent at the aforesaid solvent separating step or liquefied oil separating step and a solvent (the second coal liquefaction circulating solvent) circulated and supplied to a step other than the slurry adjusting step as required.

Accordingly, although almost of the coal liquefaction circulating agent is circulated and supplied to the slurry -17adjusting step and used as solvent, in the present invention, a part of the coal liquefaction circulating solvent is fed into an equipment for pulverizing catalyst and utilized for pulverizing limonite in the coal liquefaction circulating solvent. That is, solvent separated at the aforesaid solvent separating step or the liquefied oil separating step and obtained there is circulated and supplied to the slurry adjusting step as coal liquefaction circulating solvent and in turn a part of the solvent is supplied to the equipment for pulverizing Zlimonite in the coal liquefaction circulating solvent.

i In accordance with the process of coal liquefaction of the present invention, wearing of equipment for pulverizing catalyst having a superior pulverizing operation for iron ore used as catalyst is reduced as compared with that of the prior art process of coal liquefaction, a high activation of catalyst can be attained, the yield of liquefied oil can be improved and then a high yield of liquefied oil with a small amount of adding catalyst can be accomplished. Accordingly, since the manufacturing cost of catalyst is reduced, a required amount of catalyst is reduced to enable the yield of liquefied oil to be increased, resulting in that coal liquefaction can be carried out economically and effectively.

BRIEF DESCRIPTION OF THE DRAWINGS Fig.l is a view for showing a result of X-ray diffraction analysis in powder for limonites in the -18embodiments and the comparative examples together with a intrinsic moisture/iron atom (a molar ratio).

Fig.2 is a view for showing a relation between a molar ratio of intrinsic moisture/an iron atom of limonite (a molar ratio between an intrinsic moisture and an iron atom) and a wearing rate of pulverizing balls in accordance with the Embodiment 3 and the Comparative example 1.

Fig.3 is a view for showing a relation between a molar ratio of intrinsic moisture/iron atom of limonite (a molar ratio between an intrinsic moisture and an iron atom) and a transformation rate of coal in accordance with the .9 Embodiment 4 and the Comparative example 3.

.Fig.4 is a view for showing a relation between an amount of catalyst and the yield of liquefied oil in accordance with the Embodiment 5, the Comparative examples '0 4 and DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described as follows. As long as its gist is not changed or exceeded by the present invention, the present invention is not limited to these embodiments. Coal conversion rate and yield of liquefied oil described in the subsequent Embodiments and the comparative examples are values obtained in reference to a dry ash-free coal.

Limonites (A to L) applied in the embodiments and comparative examples and comparative examples: -19- After each of Australian limonites A to E was pulverized by a free pulverizing machine (made by NARA MACHINERY Co., Ltd.), it was dried for 8 hours at a temperature of 110"C in a vacuum. This drying operation is used for removing moisture adhered to limonite. Intrinsic moisture in limonite is not reduced through this drying operation and a molar ratio between intrinsic moisture and iron atom in limonite is not changed.

Limonite B was heated in air by an electric furnace at 200'C to 300'C for 2 to 6 hours and applied as limonites F to L. Through this heating process, the intrinsic moisture in limonite B is reduced and a molar ratio between the e intrinsic moisture and iron atom is changed. That is, this heating process was carried out for obtaining limonite having various different molar ratios between intrinsic moisture and iron atom.

Each of the aforesaid limonites A to L was put through a sieve with a mesh size of 200 meshes to obtain powder limonite passed through the meshes. The powder limonite was heated in air by an electric furnace at a temperature of 700°C for 4 hours and intrinsic moisture amount in limonites A to L was calculated in reference to a reducing amount of weight (mass) of powder limonite through this heating process.

Embodiment 1 [a survey of molar ratio between intrinsic moisture and iron atom for each of limonites A to L] Through the following change in chemical formula, the reduced weight by the aforesaid heating process was defined as an intrinsic moisture amount and the molar ratio between intrinsic moisture and iron atom of each of limonites A to L was calculated.

Heating at 700'C for 4 hours Fe 2 03*nH 2 0 (limonite) Fe 2 0 3 nH 2 0 [reduced weight (intrinsic moisture)] An X-ray diffraction analysis in powder for each of "limonites A to L was carried out.

:.In Fig.1 are indicated a result of X-ray diffraction analysis in powder and molar ratios between intrinsic 4* moisture and iron atom for each of the aforesaid limonites A to L. As apparent from Fig.l, the more the molar ratio between intrinsic moisture and iron atom for each of the C. aforesaid limonites, the higher a diffraction peak (20 21°) of a-iron oxyhydroxide, the less a diffraction peak S* (20 24') of a-iron oxide and the higher an inclusion of a-iron oxyhydroxide in limonite. Limonite A has the highest molar ratio between intrinsic moisture and iron atom, its value is 0.65 and it is corresponded to one example of limonite substantially not including iron oxide.

Embodiment 2 -21- [a survey about a transformation temperature of iron compound (a-iron oxyhydroxide, limonite, airon oxide) into pyrrhotite] An autoclave was used, hydrogen was added to slurry mixture containing iron compound, sulfur (amount: corresponding to twice in an atomic ratio in respect to an iron inclusion amount of the aforesaid iron compound) and coal liquefaction solvent, its temperature was increased up to the set temperature of 200'C to 450"C at a rate of 150'C per minute, it was rapidly cooled down to a room temperature after reaching the set temperature and a temperature where the iron compound in the slurry mixture was transformed completely into pyrrhotite was surveyed.

At this time, as iron compound, each of a-iron oxyhydroxide, limonite B, a-iron oxide was used separately.

In these substances, limonite B is limonite in which the peaks of both a-iron oxyhydroxide and a-iron oxide were acknowledged by the X-ray diffraction analysis in powder.

A transformation temperature of iron oxide into pyrrhotite was determined in detail as follows. Iron compound was separated from the slurry mixture after the aforesaid cooling processing with separation of solvent by tetrahydrofuran (THF) and recovered, then the iron compound was dried, thereafter a peak of pyrrhotite was checked by the X-ray diffraction analysis in powder.

As a result of the aforesaid check, a temperature where the iron compound is completely transformed into pyrrhotite was 350'C for a-iron oxide, 250'C for limonite -22- B, and 200'C for a-iron oxyhydroxide. As a result of this process, it is suggested that for limonite having different substance ratio of each of a-iron oxide and a-iron oxyhydroxide, limonite containing a large amount of a-iron oxyhydroxide shows a lower transformation temperature into pyrrhotite and subsequently a higher activity of catalyst.

Embodiment 3 [a pulverizing and wearing test] A ball mill is used and a degree of wear of pulverizing balls when the aforesaid limonites A, B and C (a molar ratio between intrinsic moisture and iron atom: 0.65, 0.48, 0.47) are pulverized in coal liquefaction solvent was checked as follows.

Limonite: 15g, coal liquefaction solvent: 45g and SUS316 balls with a diameter of 10 mm: 50 pieces (200 g) were fed into a vessel made of SUS316 with 250 ml and then a pulverizing operation was carried out for 4 hours. A distribution of particle size of limonite in limonite slurry obtained in this way was measured by a laser diffraction method to show that its mean particle diameter was 0.8 pm. Pulverizing balls were separated from the limonite slurry, the pulverizing balls were washed in THF by using an ultrasonic wave cleaner, dried and then their weight was measured. Then, a wearing rate of the pulverizing balls was calculated in reference to a reducing amount of weight of the pulverizing balls caused by pulverizing operation (a weight difference of the -23pulverizing balls before and after the pulverizing operation).

Comparative example 1 [a pulverizing and wearing test] A wearing rate of the pulverizing balls when limonite E (a molar ratio between an intrinsic moisture and an iron atom: 0.33) was pulverized was checked by the same method as one described in the Embodiment 3. A result of this operation will be indicated in Fig.2.

Comparative example 2 [a pulverizing and wearing test] A wearing rate of the pulverizing balls when pyrite ore is pulverized in coal liquefaction solvent was checked S.9 by the same method as one performed in the Embodiment 3 and 0P a wearing rate of the pulverizing balls was 1.7% (wt. In reference to the result of pulverizing and wearing test described above, the larger a molar ratio between "intrinsic moisture and iron atom in limonite, the lower a wearing rate of the pulverizing balls applied to pulverize limonite, wherein as compared with the case of the Comparative example 1 using limonite having a molar ratio between intrinsic moisture and iron atom of 0.33, the case of the Embodiment 3 having a molar ratio between intrinsic moisture and iron atom being 0.4 or more 0.48, 0.47) shows that a wearing rate of pulverizing balls when limonite is pulverized is quite low. In addition, as -24compared with the case of the Comparative example 2 for pulverizing pyrite ore, it is apparent that the case of the Embodiment 3 has a quite low wearing rate of pulverizing balls.

Embodiment 4 [a liquefaction activating test] The aforesaid limonites A, B, C, D and F (a molar ratio between intrinsic moisture and iron atom: 0.65, 0.48, 0.47, 0.47, 0.40) are pulverized in coal liquefaction solvent by applying a free planetary mill (made by Fliche, Model P-5) so as to obtain limonite slurry. At this time, as the pulverizing balls, the balls made of SUS316 with a diameter of 10 mm were used. A distribution of particle size of limonite in the limonite slurry was measured by a laser diffraction method and its mean particle diameter was 1.5 m.

Then, the aforesaid limonite slurry was added as catalyst to Australian Yallourn brown coal, sulfur was also added, coal liquefaction solvent was added to obtain slurry mixture. At this time, an adding amount of catalyst was wt. as iron in reference of a dry ash-free coal and an adding amount of sulfur was set to be 1.2 wt. in reference to a dry ash-free coal.

The aforesaid slurry mixture was fed into an autoclave (an inner volume: 100 ml) and hydrogenation reaction (liquefaction reaction) was carried out under conditions of an initial pressure of hydrogen: 10 MPa, a reaction temperature: 450'C and a reaction time: 30 minutes. After this test, the attained reaction product (hydrogenated product) was separated and the reaction product was dissolved by using tetrahydrofuran (THF) at a boiling point of THF and then filtered and separated by a membrane filter with a fine hole diameter of 0.2 pm. Solid phase substance obtained by this filtering and separating operation, i.e.

THF insoluble matter (not dissolved by THF) is defined as a not-yet reacted brown coal, a reacting amount of brown coal was calculated in reference to the non-reacted amount of brown coal and an amount of brown coal before hydrogenation reaction and a coal conversion (a rate of a reacting amount of brown coal in respect to the amount of brown coal before hydrogenation reaction) was calculated. This result is indicated in Fig.3.

Comparative example 3 [Activity test for coal liquefaction] Limonites E, G, H, I, J, K, L (a molar ratio between intrinsic moisture and iron atom: 0.33, 0.37, 0.34, 0.26, 0.16, 0.09, 0.00) were used as limonites. Pulverizing of limonite and liquefaction of coal were carried out by the same manner as that of the Embodiment 4 except this point and a coal conversion was calculated by the same method.

This result is indicated in Fig.3 together with the result of the Embodiment 4.

In reference to Fig.3, it is apparent that as the molar ratio between intrinsic moisture and iron atom in -26limonite is high, the coal conversion becomes high, the rate of increasing value is low at a region with a molar ratio between intrinsic moisture and iron atom in limonite being 0.4 or lower, although it is high at a region with a molar ratio between intrinsic moisture and iron atom in limonite being 0.4 or more, and catalytic activity caused by increasing a molar ratio between intrinsic moisture and iron atom in limonite, becomes remarkably high, and coal convertion is rapidly increased.

o Embodiment .:.The aforesaid limonites A (a molar ratio between intrinsic moisture and iron atom: 0.65) was pulverized in coal liquefaction solvent by applying a free planetary mill (made by Fliche, Model P-5) so as to obtain limonite slurry. At this time, as the pulverizing balls, the balls made of SUS316 with a diameter of 10 mm were used. A distribution of particle size of limonite in the limonite slurry was measured by a laser diffraction method and its mean particle diameter was 0.6 pnm. In addition, the limonite A corresponds to one example of limonite substantially not containing iron oxide as described above.

Then, the aforesaid limonite slurry was added as catalyst to Australian Yallourn brown coal, sulfur was also added, coal liquefaction solvent was added to obtain slurry mixture. At this time, adding amounts of catalyst were wt. 3.0 wt. and 6.0 wt. as iron in reference to a dry ash-free coal and an adding amount of sulfur was set in -27such a way that a concentration of hydrogen sulfide in liquefaction reaction becomes 5,000 ppm.

The aforesaid slurry mixture was fed into an autoclave (an inner volume: 5 lit.) and hydrogenation reaction (liquefaction reaction) was carried out under conditions of an initial pressure of hydrogen: 7.5 MPa, a reaction temperature: 450'C and a reaction time: 60 minutes. After this test, the attained reaction product (hydrogenated product) was separated, distilled and the liquefied oil was separated for each of boiling point ranges. As a result, the yield of liquid (liquefied oil) with C 5 to a boiling point of 420"C was 34 wt. in the case of adding amount of catalyst of 1.0 wt. 49 wt. in the case of adding amount of catalyst of 3.0 wt. and 54 wt. in the case of adding amount of catalyst of 6.0 wt. respectively. In :i Fig.4 is shown this result in a relation between the adding amount of catalyst and the yield of liquefied oil.

9**9 Comparative example 4 The aforesaid limonite E (a molar ratio between intrinsic moisture and iron atom: 0.33) was pulverized by the same method as one described in the Embodiment 5 so as to attain a mean particle diameter of limonite in limonite slurry of 0.9 pm.

The aforesaid limonite slurry mixture was used as catalyst and hydrogenation reaction was carried out by the same method as one described in the Embodiment 5, the reaction product was distilled and the oil substances were -28separated for each of boiling point ranges. As a result, the yield of liquid (oil substance) with C 5 to a boiling point of 420"C was 27 wt. in the case of amount of catalyst of 1.0 wt. 44 wt. in the case of amount of catalyst of 3.0 wt. and 53 wt. in the case of amount of catalyst of 6.0 wt. respectively. In Fig.4 is shown this result in a relation between the adding amount of catalyst and the yield of liquefied oil.

oo Comparative example Pyrite ore was pulverized by the same method as one performed in the Embodiment 5 so as to attain pyrite ore slurry. A mean particle diameter of pyrite ore in the pyrite ore slurry was 0.6 pm.

The aforesaid pyrite ore slurry mixture was used as catalyst and hydrogenation reaction was carried out by the

S

same method as one described in the Embodiment 5, the reaction product was distilled and the oil substances were 5.55 separated for each of boiling point ranges. As a result, the yield of liquid (oil substance) with C 5 to a boiling point of 420"C was 27 wt. in the case of amount of catalyst of 1.0 wt. 31 wt. in the case of amount of catalyst of 3.0 wt. and 49 wt. in the case of amount of catalyst of 6.0 wt. respectively. In Fig.4 is shown this result in a relation between the adding amount of catalyst and the yield of liquefied oil.

As apparent from Fig.4, all of the Embodiment (catalyst: limonite the Comparative example 4 -29- (catalyst: limonite E) and the Comparative example (catalyst: pyrite ore), the more the amount of catalyst, the higher the yield of liquefied oil. Comparing the Embodiment 5 with both Comparative examples 4 and 5 shows that in the case of an amount of catalyst of 6.0 wt. the yield of liquefied oil in the Embodiment 5 is higher by wt. than that of the Comparative example 5 and comparing it with the Comparative example 4 shows that it is slightly higher by 1 wt. than the former and so its difference is less in value. However, in the case of amount of catalyst .9 of 3.0 wt. or in the case of amount of catalyst of wt. the yield of liquefied oil in the Embodiment 5 is higher by 5 wt. than that of the Comparative example 4 and the Comparative example 99° In view of the foregoing, in the case of the Embodiment 5 (catalyst: limonite the same yield of 9*99 liquefied oil can be obtained even if the adding amount of catalyst is less in its volume as compared with the cases of the Comparative example 4 (catalyst: limonite E) and the Comparative example 5 (catalyst: pyrite ore) and a high yield of liquefied oil can be attained even if the low adding amount of catalyst is attained. That is, either the same or higher yield of liquefied oil can be accomplished with a less amount of adding of catalyst.

Claims (3)

1. A process of coal liquefaction including a hydrogenation step in which iron ore mechanically pulverized in coal liquefaction solvent to have a mean particle diameter of 10 pm or less is applied as catalyst and coal is hydrogenated under co-presence of solvent and catalyst characterized in that said iron ore is limonite and concurrently a molar ratio between intrinsic moisture and iron atom in said limonite is 0.4 or more. i*

2. The process of coal liquefaction according to claim 1, wherein said limonite is limonite in which iron oxide is not substantially contained.

3. The process of coal liquefaction according to claim 1 or claim 2, wherein either elemental sulfur or sulfur compound is present together with said coal, solvent and catalyst. DATED this 24 th day of April, 1998. NIPPON BROWN COAL LIQUEFACTION CO., .LTD Kooe- Skee LTD By Their Patent Attorneys: IOrnso Kce 6.--TD CALLINAN LAWRIE Ccwo C- Coo s-T~~ 0o-<'p -31-