JPH0350579B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing a catalyst for use in coal liquefaction, in which coal is hydrogenated to produce a liquid product. More specifically, the present invention relates to a method for producing a highly active catalyst that can be separated, recovered, reused, or kept in a reactor for a long period of time.

(Prior Art) A method for obtaining a liquefied product containing gas and solids by pulverizing and heating coal and adding hydrogen if necessary has been studied for many years, and many techniques are known. In recent years, due to problems such as fuel oil resources and the diversification of chemical products,
The development of coal liquefaction technology is very active, and many new technologies are being developed.

However, many problems still exist in order to efficiently obtain high-quality fuel oil, gasoline, or chemical feedstock oil. For example, the addition of expensive or environmentally undesirable catalysts, the high amount of hydrogen required to liquefy the coal, and the formation of char during the reaction.

Among them, the reaction conditions in the coal reactor, especially the selection of the catalyst, are one of the important factors for determining the quality of liquefied oil. For this reason, a wide variety of catalysts with different chemical species and physical shapes, including methods of addition, have been developed.

There are many catalysts for coal liquefaction that have been known in the past, but the typical ones include zinc chloride, zinc chloride,
Tin chloride, aluminum chloride, nickel chloride, iron chloride, etc.; sulfides include tin sulfide, molybdenum sulfide, lead sulfide, copper sulfide, zinc sulfide, nickel sulfide, iron sulfide, etc.; oxides include nickel oxide, silica, alumina, Examples include iron oxide, cobalt oxide, titanium oxide, etc., and the use of mixtures thereof, red mud, ore, etc. is also known.

The above catalyst groups can be roughly divided into three groups.
The first group is chloride-based, which exhibits excellent catalytic effects in coal liquefaction reactions. Among them, it has been reported that in the molten salt method used at high concentrations, light oil is produced abundantly, the amount of gas generated is small, and good liquefaction formation is exhibited. However, in putting this method into practical use, there are major restrictions on the material of the equipment due to the coexistence of hydrogen chloride gas.

The second group consists of Co, which is often used for heavy oil hydrogenation, etc.
It is a group of expensive metals such as Mo, Ni, and W. Although these catalysts have high hydrogenation activity, they have the drawbacks of being susceptible to poisoning and having a short catalyst life. In addition, since the catalyst is expensive, there are methods to keep the catalyst within the reactor, such as the boiling bed of the H-Coal method, or
Processes have been proposed, such as the Dow process, in which catalysts are used at very low concentrations and most of the catalyst is reused and recycled. However, none of them have reached the stage of completion yet.

The third group is iron compounds. This is inexpensive and is often used as a disposable catalyst. There are many types of iron compounds used, among them iron hydroxide,
Representative examples include red mud, iron ore, and iron sulfate. The activity of these iron compounds increases dramatically when sulfur coexists. Therefore, it has been proposed to add sulfur to coal that has a low sulfur content.

Furthermore, the catalytic activity of natural pyrite (FeS ₂ ; pyrite) is well known, and various methods for producing synthetic pyrite with higher activity have been studied (Japanese Patent Laid-Open No. 183831/1983).

Most iron compound catalysts are used with a size of several tens of microns or more, but in that case, the coal liquefaction activity is insufficient, and the coal liquefaction activity is insufficient unless it is used after being finely pulverized or classified to a size of several tens of microns or less. isn't it. On the other hand, the aforementioned synthetic pyrite, iron hydroxide, or finely pulverized iron ore and pyrite are fine particles with a particle diameter of about several μm and have high coal liquefaction activity. These particulate highly active catalysts are relatively expensive, and therefore, from the economic point of view, it is desirable to separate and recover them from coal-derived products such as coal liquefied oil and coal ash for reuse. Therefore, a method of using granulated and dried fine iron sulfide as a catalyst, making its sedimentation rate higher than that of ash, recovering it by gravity concentration separation method, and recycling and reusing it (Japanese Patent Application Laid-Open No. 59-210992) Publication No.),
A method in which fine particles of iron sulfide are granulated and dried, and then calcined to make them resistant to pulverization, are used as a catalyst, recovered by gravity concentration separation method, and recycled for reuse. 23687) are being considered.

(Problems to be Solved by the Invention) By using as a catalyst a granulated and dried fine grained iron compound, or one which has been further calcined, the coal liquefaction activity is high, and furthermore, by gravity concentration separation method, coal liquefaction activity is high. It can be collected and reused. However, when fine-grained iron sulfide is synthesized, a preparation process is required, and when natural iron sulfide is used, a sophisticated pulverization process is required to a size of several microns or less. Further, during granulation and drying, there are problems such as the need for sophisticated stirring operations in order to prevent precipitation of iron compounds and obtain a uniform slurry.

(Means for Solving the Problems) In order to solve the above problems, as a result of intensive research, the present inventors have discovered a complicated process such as synthesis of fine particles of iron compounds or pulverization of natural iron compounds. By drying and granulating an aqueous iron compound solution without any treatment, and then calcining it at 400 to 1500℃, we invented a highly active catalyst that can be recovered and reused using the gravity concentration separation method. .

That is, the present invention is a method for producing a catalyst for coal liquefaction, characterized in that an aqueous solution of an iron compound is granulated while drying, and then calcined at 400 to 1500°C.

The method of the present invention will be explained in detail below.

The aqueous solution of an iron compound means an aqueous solution of divalent or trivalent iron salts, and iron salts include ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, ferrous nitrate, Any material can be used, including ferric nitrate and the like.

As a method for granulating while drying, known techniques such as a spray drying granulation method and a fluidized drying granulation method can be applied. The particle size of the catalyst during granulation is selected to be suitable for separation from ash, depending on the method of use, reaction conditions, etc. For example, if the catalyst is supplied to the reactor as a slurry with coal and hydrocarbon oil as a solvent and a hydrocyclone is used to separate the coal liquefied oil and ash, the particle size of the catalyst may be between 5 and 200μ. , preferably 10 to 100μ.
If it is less than 5μ, it will be difficult to collect it with a liquid cyclone, and if it exceeds 200μ, there will be concerns about reactor clogging due to accumulation in the reactor.
In addition, when catalyst particles are retained in the reactor and only ash and coal liquefied oil are flowed out of the reactor for separation, the particle size of the catalyst should be at least 100 μm, but
Desirably, the thickness is selected from 200μ to several cm. If it is less than 100μ, the catalyst will dissipate to the outside of the reactor.

Other metals, curing agents, etc. may be added to the aqueous solution of the iron compound. Also, depending on the raw materials, the strength of the product may be weak during dry granulation, but in this case, inorganic binders such as silicic acid compounds, aluminum compounds, phosphoric acid compounds, or Organic binder such as polyvinyl alcohol, 1 to 200% by weight (dry) based on iron.
It is also good to add.

Coal liquefaction activity and strength can be increased by calcining the dry and granulated catalyst at 400-1500°C. Below 400°C, the increase in coal liquefaction activity and strength is insufficient, and above 1500°C, the coal liquefaction activity decreases due to a decrease in the specific surface area of the catalyst, etc. As the firing method, known techniques such as a rotary kiln, a tunnel furnace, a fluidized bed furnace, etc. can be applied. The firing atmosphere may be oxidizing, reducing, or inert, but it is preferable to perform the firing in a low oxygen concentration atmosphere. If mixing of oxygen cannot be prevented, reducing substances such as coke or sulfur may be mixed and fired.

The present invention liquefies coal using the catalyst prepared by the method described above, and the method for liquefying coal will be explained in more detail below.

Coal as used in the present invention refers to anthracite coal, bituminous coal, subbituminous coal, charcoal, peat, and the like. As the coal used in the present invention, bituminous coal, subbituminous coal, and charcoal are more preferable.

Coal heating is carried out at 350-800°C. When the temperature is low, the liquefaction rate is slow, and when the temperature is high, carbide and gas increase. 400-500°C is most preferred.

In the present invention, it is possible to liquefy without using hydrogen, for example, using a pre-hydrogenated catalyst, but the liquefaction rate may not improve depending on the conditions. Therefore, it is common to carry out the liquefaction reaction in the presence of hydrogen, and it is desirable to use hydrogen with the highest possible purity.

Further, the pressure during the hydrogen reaction is preferably 10 Kg/cm ² or more, and optimally 100 to 300 Kg/cm ² . The hydrogen reaction is complex, and an appropriate pressure is selected depending on the structure of the coal, the slurry solvent to be mixed, etc.

In the present invention, liquefaction refers to turning most of the coal into a liquid whose boiling point is above room temperature (approximately 20 degrees Celsius) and below 900 degrees Celsius when converted to normal pressure. It may contain things. Therefore, the crude oil produced in the present invention refers to a mixture containing these substances.

In coal liquefaction using the catalyst of the present invention, hydrocarbon oil is used as a catalyst at a weight ratio of 50% to coal.
% or more, preferably 100 to 400%.

The hydrocarbon oil used here is liquefied coal oil or oil obtained by hydrogenating liquefied oil, and aromatic hydrocarbons, aliphatic hydrocarbons, acidic oils, basic oils, sulfur compounds, etc. are used. Mixed oils containing these oils such as creosote oil and anthracene oil, petroleum fractions, and the like can also be used. The boiling point of hydrocarbon oil is under normal pressure.
A temperature range of 150℃ or higher and up to 600℃ is preferable.

The catalyst of the present invention can be continuously supplied to and discharged from a reactor to separate the catalyst from the resulting crude oil for circulation and reuse, or by allowing the catalyst to remain in the reactor. Any method that performs separation by draining only the ash and coal liquefied oil out of the reactor can be applied. In the former case, the amount of catalyst added may be any amount from 0.01 to 30% by weight relative to coal, but is most preferably from 1 to 20%.

When the catalyst is continuously supplied to and discharged from the reactor, any method can be used to recover the catalyst particles from the resulting crude oil, but in particular gravity concentration such as hydrocyclone or centrifugation is acceptable. Preferably, separation methods are used to preferentially recover the catalyst. For example, in the hydrocyclone method,
A hydrocyclone core with a diameter of 10 mmφ or more, preferably 10 to 75 mmφ is used, and the pressure drop per stage of the hydrocyclone is 1 Kg/cm ² or more, preferably 1 to 6 Kg/cm2.
It is better to drive in cm ² .

This gravity separation or centrifugation can also be performed in one or more stages, or in multiple stages. The remaining upper layer oil liquid, in which the catalyst has been precipitated to some extent in the first stage, is applied to the second stage separation device, and the catalyst can be efficiently concentrated under centrifugal conditions that take into account the viscosity and particle size. It is.

Thus, most of the catalyst initially present in the crude oil produced from coal liquefaction can be recovered efficiently and with limited ash recovery, with 70-90% catalyst recovery under suitable conditions. It is possible.

The catalyst recovered in this way (more precisely, a slurry liquid in which catalyst particles are suspended) is mixed with the reaction feed liquid, but only the amount of catalyst lost as a supernatant is mixed in the reaction feed liquid. That will be enough.

Regarding the method of mixing with the reaction feed liquid, the recovered catalyst may be dispersed in a solvent hydrocarbon oil in advance, or it may be fed into a slurry preparation process. That is, as long as the reaction feed liquid eventually contains the recovery medium, any mixing procedure may be used.

In order to keep the catalyst particles in the reactor for a long time and allow only the catalytic hydrocarbon oil and coal-derived products to flow out of the reactor, known techniques such as fixed bed type, moving bed type, and fluidized bed type are used. is applicable. Note that the flow of the slurry may be either an upward flow or a downward flow, but
Upflow is more preferred in order to cause the ash to flow out of the reactor.

In a continuous upward flow tower type reactor, the settling velocity of ash in the produced oil at the temperature and pressure inside the reactor is sufficiently smaller than the linear velocity of movement of the produced oil in the reactor, and under the same conditions It is necessary that the settling velocity of the catalyst in the produced oil is sufficiently greater than the linear velocity of movement of the produced oil in the reactor. The terminal velocity of sedimentation of a particle in a fluid, U _n , is generally defined as: Um = √4 ( _p −) _p 3... Um: Terminal velocity of a particle (m/sec) g: Acceleration of gravity (m/sec ² ) ρ _p : Density of solid particles (Kg/m ³ ) ρ : Density of fluid (Kg/m ³ ) D _p : Diameter of particles (m) C Coefficient of drag of particles (-) The average particle size of ash is 2~
10μ, true specific gravity is around 2, and its sedimentation rate can be determined by the formula. With respect to this value, the catalyst particle size, reactor design conditions, operating conditions, etc. are set in order to satisfy the above-mentioned requirements.

Thus, most of the catalyst remains in the reactor for a long time, and only solvent hydrocarbon oils and coal-based products such as produced oil, ash, unreacted coal, etc. can flow out of the reactor. The amount of catalyst added to the reaction feed liquid may be only the amount of catalyst lost by being discharged outside the reactor due to atomization or the like.

(Effects of the invention) According to the present invention, the catalyst for coal liquefaction is highly active and can be separated, recovered and reused, or left in the reactor for a long period of time, with a very simple process compared to the conventional technology. can be manufactured. In the process of drying and granulating, since the iron compound is an aqueous solution,
Clogged pipes such as those caused by slurry-like raw materials,
Troubles such as abrasion are also extremely rare in the method of the present invention, and sophisticated stirring operations for uniformity are not required. Therefore, as a result, the catalyst can be manufactured at low cost. In addition, since it can be separated, recovered, reused, or kept in a reactor for a long period of time, the amount of catalyst used can be significantly reduced in the coal liquefaction process, resulting in an economical effect. Furthermore, it is also an environmental measure due to effective use of resources and less waste catalyst.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Dissolve ferrous sulfate in water to make a 20% by weight aqueous solution, add Silcasol with a concentration of 30% by weight so that the ratio of silica to iron is 20% by weight, and mix well to form a homogeneous solution. shall be.

Inlet air temperature of rotating disc spray dryer
250℃, outlet gas temperature 130℃, hot air volume 7Nm ³ /min,
A rotating disk with a diameter of 80 mmφ was operated at 32000 rpm, and the previously prepared solution was fed at 22/H.
It was granulated while drying. Further, to this granulated material, powdered sulfur in an amount equal to the weight of iron contained in the granulated material was added, and sintering was performed at 600.degree. C. for 2 hours under nitrogen gas flow. The product obtained above is the catalyst produced by the method of the present invention. The particle size distribution of the catalyst produced at this time is shown in FIG. The average particle size was approximately 15μ.

A coal liquefaction reaction experiment was conducted using the catalyst prepared as described above. The equipment has a coal processing scale
A continuous reactor with a capacity of 20 kg/day was used. The operating conditions are as follows.

(1) Coal: Horonai coal (400 mesh pass) (2) Solvent: Decrystallized anthracene oil (3) Catalyst concentration: 10% iron weight per anhydrous ash-free coal (4) Reaction pressure: 200Kg/cm ² (5) Reaction Temperature: 460°C The crude oil thus produced was fed into a liquid cyclone with a body diameter of 10 mm at a slurry flow rate of 200/H and a temperature of 80°C. The flow rate ratio at this time was 44%. This flow rate ratio is the ratio of the downward flow rate to the feed flow rate. As a result, the ratio (recovery rate) of the amount of catalyst and ash contained in the separated upward flow and downward flow to the respective amounts contained in the feed flow rate of the hydrocyclone. FIG. 2 shows a plot of the difference in particle size for each particle size. According to this, the particle size of the ash contained in the general crude oil produced is about 3 μm, so the recovery rate is about 40% as shown in Figure 2. On the other hand, the recovery rate of a catalyst with an average particle size of 15 μm is about 90%, and sufficient preferential concentration recovery is possible. Also,
From FIG. 2, it can be seen that when a fine catalyst with a particle size of 2 to 3 μm is used, the recovery rate is 40 to 50%, which is not much different from the recovery rate of ash, indicating that it is difficult to preferentially concentrate and recover the catalyst.

Furthermore, FIG. 3 compares the results of coal liquefaction reactions between the catalyst according to the present invention and other iron-based compound catalysts. The catalysts used as controls were an artificially synthesized fine particle iron compound catalyst and red mud, and the particle size distribution of each is shown in FIG. The synthetic fine particle iron compound catalyst was manufactured according to the example of Japanese Patent Application No. 58-58645, and was manufactured by the following method.

230 g of iron was taken as a 1:1 mixture of ferrous sulfate and ferrous acetate, and dissolved in 4 pure water. 610 g of sodium sulfide pentahydrate was dissolved in 4 pure water. These two liquids were mixed, the pH was adjusted to 6 using sulfuric acid, 184 g of sulfur powder was added to the resulting slurry, mixed well, and reacted at 80° C. for 40 hours with stirring. The reactor was operated with a small amount of nitrogen flowing through it. The slurry after the reaction was filtered to recover the solid content, which was further dried to obtain a catalyst. In addition, red mud is finely ground and further classified, and has an iron content of 36%.

The coal liquefaction reactions of the catalyst of the present invention and the two controls were carried out using a stirred autoclave with an internal volume of 1, and the reaction conditions were as follows.

(1) Coal: Pacific coal (400 mesh passes), 60 g as anhydrous ash-free coal (2) Solvent: 120 g of decrystallized anthracene oil (3) Catalyst concentration: 1.8 as iron weight per anhydrous ash-free coal
% (4) Hydrogen charging pressure: 105Kg/cm ² (reaction pressure 190~200
Kg/cm ² ) (5) Reaction temperature: 450℃ (6) Reaction time 80 minutes (7) Additives: For the catalyst and red mud of the present invention, powdered sulfur was added in an amount 0.9 times the weight of iron contained in the catalyst. The horizontal axis in FIG. 3 is the weight fraction of hexane-soluble oil relative to the total oil, and can be considered as a measure of the degree of hydrogenation. Here, the total oil refers to the total weight of hexane-soluble oil, asphaltene, and pre-asphaltene. The vertical axis indicates the weight fraction of the light oil produced relative to the charged anhydrous ash-free coal, which is considered as a measure of the degree of hydrocracking. The light oil referred to herein refers to a substance having a carbon number of 5 or more, such as hexane, and having a boiling point of 300° C. or less at normal pressure.
This figure slopes upward in the direction of liquefaction and lightening, and can be used as a measure of catalyst activity.

From FIG. 3, it is clear that the activity of the catalyst according to the present invention is much higher than that of red mud and approximately on the same level as that of the fine-grained synthetic iron compound catalyst.

[Brief explanation of drawings]

FIG. 1 shows a catalyst according to the present invention shown in Examples,
Figure 2 shows the particle size distribution of artificially synthesized fine grained iron compound catalyst and red mud in cumulative amounts. Figure 3 is a graph plotting the ratio of the amount of catalyst and ash contained in the catalyst to the amount in the feed liquid to the cyclone (recovery rate) against the particle size. This is a chart showing the activity of coal in the coal liquefaction reaction.

Claims (1)

[Claims] 1 After drying and granulating the iron compound aqueous solution,
A method for producing a catalyst for coal liquefaction, which comprises firing at a temperature of 400 to 1500°C.