JPS6333421B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a catalyst for coal liquefaction.

(Prior Art) A method for obtaining a liquefied product containing gas and solids by pulverizing and heating coal and adding hydrogen as 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, it may require the addition of expensive or pollutantly undesirable catalysts;
The problem is that a large amount of hydrogen is required to liquefy coal, and that carbide is generated 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, various types of catalysts in which the chemical species have different physical forms have been developed, including the methods of addition.

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 results are shown. 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. Also,
Because the catalyst is expensive, there are methods to keep the catalyst in the reactor, such as the boiling bed of the H-Coal method, or to use the catalyst at a very low concentration, such as the Dow method.
A process has also been proposed in which most of the waste 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 which iron hydroxide, red mud, iron ore, iron sulfate, etc. are representative. 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 have been investigated.

Conventionally, such catalysts are made by reacting an aqueous sodium sulfide solution with an aqueous iron sulfate solution at room temperature or lower, and filtering or centrifuging the resulting slurry to remove Na ⁺ and Fe ² remaining dissolved in water. After removing and desalting SO ₄ ^2- , sulfur powder was added to the remaining slurry and reacted at about 80°C for 2 to 6 days. The resulting slurry was cooled, filtered or centrifuged, and then treated with hydrochloric acid ^. The material after washing away unreacted iron sulfide and removing residual sulfur with carbon disulfide or the like was used as a catalyst for coal liquefaction. (For example, Sandea National Laboratory Energy Report No. 80-2793 in the United States) The wet synthesis method described above can easily produce fine pyrite with a very sharp particle size distribution and an average particle size of 1 to 5 μm. However, it has the disadvantage that the overall reaction time is extremely long and production efficiency is low.

On the other hand, the dry synthesis method shown by the present inventors (Japanese Patent Application Laid-open No.
59-155495, JP-A-59-166586), etc., have the advantage of being able to prepare pyrite in a few hours, but on the other hand, the particle size distribution of the product tends to be broad, and it is difficult to produce fine pyrite. In order to do this, it has the disadvantage that sufficiently fine raw materials must be prepared.

(Problems to be Solved by the Invention) As mentioned above, the conventional wet synthesis method and dry synthesis method each have advantages and disadvantages, and it is desired that a method that combines the advantages of both methods and eliminates the disadvantages be developed. It was rare.

(Means for solving the problem) The present inventors conducted research in accordance with the above-mentioned request, and found that the very small solid content of 0.5 to 2μ generated in the first stage reaction was separated into solid and liquid. After that, we discovered that by mixing sulfur with this solid content and causing the reaction at a temperature of 200°C or higher and lower than 700°C, the reaction could be completed in an extremely short time of 10 minutes to 2 hours. We have completed a method that combines the advantages of the above and eliminates the disadvantages.

That is, the present invention mixes an alkaline aqueous solution containing sulfur ions and an acidic aqueous solution containing iron ions, performs solid-liquid separation of the resulting slurry,
Mix sulfur with the obtained solid content and heat at 200℃ or higher to 700℃
The present invention provides a method for producing a catalyst for coal liquefaction, which is characterized in that the reaction is carried out at a temperature lower than that of the present invention.

In the present invention, the alkaline aqueous solution containing sulfur ions is, for example, an aqueous solution of sodium sulfide, ammonium sulfide, potassium sulfide, calcium sulfide, etc., or a solution obtained by absorbing hydrogen sulfide gas into an alkaline aqueous solution. These aqueous solutions are generally used at a sulfur ion concentration of 0.1 to 4 molar, depending on the solubility of the salt and the temperature. Further, the purity of these reagents is sufficient to be at the level of industrial chemicals, or an aqueous solution of a salt consisting of sulfur and alkali, which is a by-product in the process of treating hydrogen sulfide gas, may be used as is. Furthermore, the alkali may be a mixture instead of just one type.

The acidic aqueous solution containing iron ions is, for example, an aqueous solution of iron acetate, iron sulfate, iron nitrate, iron oxalate, iron chloride, or a solution in which iron is dissolved in an inorganic or organic acid. Of the iron ions, either ferrous or ferric ions may be used, but if forced,
Ferrous ions are preferred. These salts may also be industrial reagents or by-products from other processes. Furthermore, it is also desirable to use iron ore dissolved in acid or as a mixture of various iron salts. The concentration of iron ions in this aqueous solution is also generally preferably used within a range of 0.1 to 4 mol. If the concentration of these aqueous solutions is too thin, it is economically disadvantageous, and if the concentration is too thick, the temperature must be raised more than necessary to increase solubility. In the reaction between an alkaline aqueous solution containing sulfur ions and an acidic aqueous solution containing iron ions (hereinafter referred to as the 1-stage reaction), the sulfur ions and iron ions are reacted in approximately equimolar amounts, but the pH of the liquid after the reaction is 2 or more and less than 7. The mixing ratio of both is preferably adjusted to be 4 or more and 6 or less.

This reaction progresses instantaneously, and the black color indicates the average particle size.
Very small particles of 0.5 to 2μ are generated. next,
The solid-liquid separation operation of the slurry thus generated can be performed by using one or a combination of two or more known solid-liquid separation techniques such as filtration, centrifugation, gravity sedimentation, and hydrocyclone methods. It can be implemented by However, during this solid-liquid separation process, it is preferable that alkali ions and acid ions dissolved in the liquid be removed as much as possible. For this purpose, the use of an ultrafiltration membrane or the like is also effective. If the resulting solid content has a particularly high moisture content, heat may be applied to evaporate the moisture.

Sulfur may be in powder or liquid form. When sulfur is mixed into the obtained solid content, the mixing ratio is not particularly limited, but preferably the atomic ratio of sulfur to iron in the solid content is 0.5 to 3.

If the reaction temperature is less than 200°C, the reaction rate will be slow, and the reaction temperature will be lower than 700°C.
Since iron cannot take a sufficiently sulfurized form at temperatures higher than .degree. C., the temperature must be 200.degree. C. or higher and lower than 700.degree. C., preferably 200.degree. C. or higher and 500.degree. C. or lower.

The reaction time varies depending on the reaction temperature and the type of iron compound used as a raw material, but is several minutes or more, preferably about 10 minutes to 2 hours.

In practicing the invention, it is preferred that all steps be carried out in a very low oxygen atmosphere. For this purpose, it is preferable to carry out the process in an inert gas atmosphere such as nitrogen or argon gas. This is because both the precipitate produced during the process and the final product are susceptible to oxidation.

The effect of the present invention is that a catalyst with high activity and very fine particles can be easily and stably produced in a short reaction time, and the productivity of the catalyst is increased, resulting in a large economic effect.

The present invention is characterized by a method for preparing iron sulfides, and compared to natural iron sulfides such as pyrite, marcasite, and pyrrhotite, similar patterns are observed by X-ray diffraction, etc. However, as shown in the examples, the activity of the catalyst involved in the coal liquefaction reaction is much higher in the catalyst prepared according to the present invention.
Although the details of this reason are unknown, it is presumed that it probably originates from the surface area and surface condition. By the way, the surface area of crushed natural pyrite of 200 mesh or less is 0.1 to 5 m ² /g, at most 10
m ² /g or less, whereas the catalyst prepared by the method of the present invention has an area of 30 to 200 m ² /g. Further, most of the catalysts prepared by the method of the present invention have a small particle size of 0.05 to 5 μm.

The coal liquefaction reaction using the catalyst of the present invention does not require the separate addition of sulfur, unlike when a general iron compound is used as a catalyst.

When the catalyst prepared in advance as described above is used, the coal liquefaction performance is significantly superior to that of a method in which an iron compound and sulfur are simply supplied to the reaction system as a catalyst.

(Effects of the Invention) The effects of the present invention are that a highly active and very fine catalyst can be produced easily and stably in a short reaction time, which increases the productivity of the catalyst and has an economical effect. big.

(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.

Example 1.65 kg of ferric nitrate nonahydrate was dissolved in 4 distilled water. Furthermore, 520 g of trihydrate of sodium sulfide was mixed with the distilled water from step 4, and dissolved by heating to 50°C. These two liquids were mixed, the resulting slurry was washed with water, and 240g of sulfur powder was mixed with the resulting solid content.
Put this into a quartz tube and while flowing nitrogen gas
After drying at 110°C for 1 hour, the temperature was raised to 300°C and heated for 1 hour. All intermediate washing, etc., was carried out in a glove box with nitrogen gas flowing through it.

The results of the coal liquefaction reaction between the thus prepared catalyst of the present invention and other typical iron-based compound catalysts are compared and shown in the drawing.

The figure shows the results of activity evaluation in a 0.5 autoclave. Illinois No. 6 coal was used as the coal, hydrogen charging pressure was 80 Kg/cm ² (pressure at reaction temperature was approximately 150 Kg/cm ² ), reaction time was 30 minutes, and reaction temperature was 460°C.
A liquefaction reaction was carried out. The amount of catalyst used was 10% by weight of iron per anhydrous ash-free coal. Decrystallized anthracene oil was used as a solvent, and twice the amount by weight of anhydrous ash-free charcoal was added.

The horizontal axis of the drawing represents the weight fraction of hexane-soluble oil relative to the total oil, which 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 here refers to a substance having a carbon number of 5 or more, such as hexane, and a boiling point of 300° C. or less at normal pressure.

This diagram becomes upward-sloping to the right as liquefaction progresses in the direction of lightening, and as a result, it can be used as a measure of catalytic activity.

In the drawings, and indicate the reaction results using the following catalysts, respectively.

Catalyst prepared by the method of the present invention Mineral pyrite Electrolyzed iron powder + sulfur The above-mentioned mineral pyrite is pyrite produced at Tanahara Mine in Okayama Prefecture, which has been crushed to 200 mesh or less. Electrolytic iron powder is commercially available electrolytic iron powder with a mesh size of 325 mesh or less. The amount of sulfur added at this time was equimolar to that of iron.

It is clear from the figures that the catalyst prepared according to the invention has both a high degree of hydrogenation and a high degree of hydrogenolysis and exhibits excellent activity compared to other catalysts.

[Brief explanation of the drawing]

The drawing is a chart showing a comparison of the activity in the coal liquefaction reaction of the catalyst used in the present invention and other catalysts.

Claims (1)

[Claims] 1. Mix an alkaline aqueous solution containing sulfur ions and an acidic aqueous solution containing iron ions, perform solid-liquid separation of the resulting slurry, mix sulfur with the resulting solid content, and heat at a temperature of 200°C or more and less than 700°C. 1. A method for producing a catalyst for coal liquefaction, which comprises reacting with: