JPS5839877B2 - Coal liquefaction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coal liquefaction method using a medium-to-heavy oil component obtained by liquefying coal as a coal liquefaction solvent, and a base contained in the medium-to-heavy oil component. The purpose is to increase the hydrogenation efficiency of medium and heavy oil components by removing heavy and acidic compounds, and to improve the liquefaction efficiency.

The principle of coal liquefaction is to convert coal, which is a high molecular compound, into light, medium and heavy oil components, which are low molecular compounds.The method is to liquefy coal by adding hydrogen to the coal under high temperature and high pressure. .

A solvent is generally required in such a coal liquefaction reaction.

The reason is that coal is solid, so 200 to 9/cr
This is because it is difficult to continuously feed a constant amount of coal into a high-pressure system such as A, so finely pulverized coal is mixed with a solvent to form a slurry to facilitate feeding into the system.

On the other hand, the solvent also has the ability to uniformly disperse and stabilize the liquefied product.

Furthermore, when the solvent has hydrogen donating properties, it plays an important role not only for forming a slurry but also directly influencing the liquefaction reaction.

Therefore, the most desirable properties of the solvent are that it be a medium oil that facilitates operation, and that it has a hydrogen donating ability that promotes the reaction.

For this purpose, medium and heavy oil components obtained by liquefying coal have been used as solvents for coal liquefaction, either as they are or after being hydrotreated.

Medium and heavy oil components have a strong affinity with coal and have an appropriate viscosity, so when mixed with coal to form a slurry, they form a stable slurry and are suitable as a slurrying solvent.

However, although these medium and heavy oil components have the ability to act as a medium oil, they lack the ability to donate hydrogen to coal in a liquefaction reaction.

This property is particularly noticeable in medium and heavy oil components rich in naphthalenes, phenanthrenes, and anthracenes with a boiling point of 211° C. or higher.

If these medium/heavy oil components have the ability to donate hydrogen, the iron/heavy oil components are hydrotreated to convert them into hydrogen-donating components.

Through this hydrogenation treatment, for example, naphthalenes are converted to tetrawanes, phenanthrenes are converted to hydrophenanthrenes, and anthracenes are converted to hydroanthracenes, each of which has hydrogen donating properties.

The above hydrogenation method uses a catalyst in which at least two elements selected from Mo, W, Co, Ni, etc. are supported on an Al2O3 carrier at a temperature of 300 to 450°C and a hydrogen pressure of 5.
A method of hydrogenation under conditions of 0 to 150 kg/cd is used.

However, this hydrogenation treatment had the following problems.

That is, when medium/heavy oil components are directly hydrogenated, hydrogen is not consumed only for converting it into a hydrogen-donating substance, but is consumed for lightening, etc.

In particular, acidic compounds with OH groups such as phenol and cresol consume a large amount of hydrogen because -OH reacts with hydrogen to produce water, and basic compounds such as quinoline, pyridine, and indole are adsorbed on the catalyst active site. Perhaps to do this, the hydrogenation rate is slowed down.

Therefore, the presence of acidic or basic compounds reduces the hydrogenation efficiency of the solvent.

On the other hand, since basic or acidic compounds accelerate the dissolution reaction of coal in a solvent, decomposition of the polar functional groups of these compounds in the hydrogenation process is not preferable from the standpoint of the liquefaction reaction.

Therefore, the inventors investigated various methods for increasing the hydrogenation efficiency of medium-to-heavy oil components and the liquefaction efficiency. We have discovered a method that enables economical and efficient hydrogenation and improves the liquefaction rate of coal by providing a removal step.

That is, in the hydrogenation process of medium-to-heavy oil components, basic and acidic compounds are extracted and removed and then hydrogenated, and the basic and acidic compounds are removed again from the medium-to-heavy oil after hydrogenation. It is characterized in that the solvent added to the components is used as a solvent for coal liquefaction.

According to this method, the influence of basic and acidic compounds contained in medium and heavy oil components can be avoided, so hydrogen is consumed only for conversion to hydrogen-donating substances in the hydrogenation process. , and can be effectively converted into a hydrogen-donating component, and the polar functional groups of basic and acidic compounds are not decomposed.

Therefore, hydrogenation of medium and heavy oil components can be carried out economically and efficiently, and the efficiency of coal liquefaction can be further improved.

In this invention, as a method for removing basic compounds in medium/heavy oil components, medium/heavy oil is treated with an aqueous solution containing acids such as hydrochloric acid, nitric acid, or sulfuric acid, or with water or a mixture of water and methanol. Wash with

In addition, as a method for removing acidic compounds in medium and heavy oil components, medium and heavy oil is washed with alkalis such as sodium hydroxide, potassium, and sodium carbonate, or with water or a mixture of water and methanol. .

When basic compounds are removed by the above method,
Hydrogenation of heavy oil is carried out, and then alkalis such as sodium hydroxide, potassium, and sodium carbonate are added to the aqueous solution containing the removed basic compounds to the hydrogenated oil to release basic compounds. A compound is added and used as a solvent for coal liquefaction.

In addition, after the acidic compounds are removed by the above method, the medium/heavy oil is subsequently hydrogenated, and the hydrogenated oil is added to an aqueous solution containing the removed acidic compounds with acids such as hydrochloric acid, sulfuric acid, and nitric acid. An acidic compound liberated by adding caloric acid is added and used as a solvent for coal liquefaction.

Note that basic and acidic ion exchange resins can also be used to remove basic and acidic compounds in medium and heavy oil components.

Next, an example of a liquefaction process for carrying out the method of this invention will be explained based on the drawings.

In the figure, 1 is a stirring tank for mixing coal and solvent, 2 is a heating furnace,
3 is a liquefaction reaction tower, 4 is a hydrogen supply device, 5 is a gas-liquid separation tower,
6 is a distillation column, 7 is a column for extraction and removal of basic and acidic compounds in medium and heavy oil components, 8 is a hydrogenation reaction column, and 9 is a recovery column for basic and acidic compounds.

That is, raw coal C and solvent S are stirred and mixed in a stirring tank 1 to form a slurry, and this coal slurry is heated to a predetermined temperature in a heating furnace 2 and sent to a liquefaction reaction tower 3, where it is supplied from a hydrogen supply device 4. react with hydrogen.

After the liquefaction reaction, the product is separated into a gas component and a liquid component in a gas-liquid separation column 5, and the liquid component is separated in a distillation column 6 into light oil P1, medium/heavy oil P2, and residue P2. The basic compounds or acidic compounds are removed from the quality oil P2 by the washing liquid W1 in the extraction removal tower 7, and the medium/heavy oil from which the basic and acidic compounds have been removed is subjected to hydrogenation treatment in the hydrogenation reaction tower 8.

On the other hand, the basic and acidic compounds extracted and removed by the cleaning solution are washed and liberated by the backwashing solution W2 in the recovery tower 9, and added to the medium/heavy oil after hydrogenation treatment to be used as a solvent S for coal liquefaction. .

Next, embodiments of the invention will be described.

〔Example〕

Using a rotary autoclave with an internal volume of 5 tons, the reaction temperature was 4.
50℃, reaction time 240 minutes, initial hydrogen pressure 100kg/ca
A solvent-free liquefaction experiment of coal having the properties shown in Table 1 was conducted under the following conditions.

After the reaction was completed, the contents inside the autoclave were sampled, the inside of the autoclave was washed with benzene, the washed contents and the sampled contents were combined, and the mixture was extracted with 1**t of benzene at 80°C for 1 hour. The mixture was suctioned and filtered through a glass filter to separate tear fluid (benzene soluble content) and sap residue (benzene insoluble content).

Next, the tear fluid (benzene soluble content) was poured into an evaporator, and the benzene was distilled off.

The solvent-free liquefaction experiment was carried out five times by treating 2 kg of coal once, and a total of 5001 coal extracts were obtained.

Next, this extract is separated into each fraction in a precision distillation column, and after taking out the fraction with a boiling point of 211 to 350°C (medium and heavy oil components), it is hydrotreated using the following three methods. Three types of coal liquefaction solvents were obtained.

The results of the first hydrogenation treatment are shown in Table 2.

The above fraction was hydrogenated using a Mo-Ni-Al2O3 catalyst in a fixed bed small reactor on a scale of 50 CC/Hr,
Hydrotreated product Q1 was obtained.

The conditions at that time were LH8V1, reaction temperature 400° C., hydrogen pressure 100 kg/crA, and hydrogen/raw material molar ratio 7.

(B) As a pretreatment of the above fraction, use a stirring mixer to
% sulfuric acid aqueous solution in a ratio of 1:1, stirred for 1 hour, left to stand, and separated the oil phase (containing basic compounds), and then mixed with 3% sodium hydroxide in a 1:1 ratio. After stirring for 7 hours and allowing to stand still, the oil phase (containing acidic compounds) was separated and (A
) Hydrogenation was carried out under the same conditions as
I got 2.

(C) Add sodium hydroxide to the aqueous solution containing the basic compound removed in (B) and add hydrochloric acid to the aqueous solution containing the acidic compound to liberate the basic and acidic compounds, respectively. The hydrotreated product P2 obtained in B) was mixed to obtain the hydrotreated product Q3.

Next, the above three types of hydrotreated products Q1 component, Q2 component, and Q3 component were used as a coal liquefaction solvent, and the internal volume was 500.
Using a CC electromagnetic induction stirring autoclave, the reaction temperature was 420°C, the reaction time was 60 minutes, and the initial hydrogen pressure was 50 kg/c.
Coal having the properties shown in Table 1 was liquefied under rti conditions.

The results are shown in Table 3. From the results in Table 2, it can be seen that if acidic and basic compounds are removed before hydrogen treatment of medium and heavy oil components, hydrogenation can be carried out efficiently in a short time.

In addition, from the results in Table 3, the liquefaction rate is higher when using the Q2 component obtained by hydrogenating after removing acidic and basic compounds before the hydrogenation treatment compared to the Q1 component. It can be seen that an even higher liquefaction rate can be obtained with the Q3 component to which the acidic and basic compounds removed in the above are added.

[Brief explanation of the drawing]

The drawing is a system diagram showing an example of a coal liquefaction process for carrying out the present invention. 1... Stirring tank, 2... Heating furnace, 3...
...Liquification reaction tower, 4...Hydrogen supply device, 5
...gas-liquid separation column, 6...distillation column, 7.
...Extraction removal column, 8...Hydrogenation reaction column,
9...Recovery tower, C...Coal, S...
...Solvent, Wl, W2...Cleaning liquid.

Claims (1)

[Scope of Claims] 1. A coal liquefaction method in which a medium/heavy oil component obtained by liquefying coal is hydrotreated and used as a coal liquefaction solvent, wherein the basicity in the medium/heavy oil component, A method for liquefying coal, which comprises extracting and removing acidic compounds, followed by hydrogenation, and adding the above-mentioned basic and acidic compounds to medium and heavy oil components after hydrogenation and using them as a solvent for coal liquefaction. 2. As a method for extracting and removing basic compounds in medium and heavy oil components, the basic compounds are washed with an aqueous solution containing acids such as hydrochloric acid and nitric acid, or with water or a mixture of water and methanol. 2. A method for liquefying coal according to claim 1, which comprises adding alkalis such as sodium hydroxide, potassium, and sodium carbonate to the aqueous solution to liberate basic compounds. 3. As a method of extracting and removing acidic compounds in the middle 1 heavy oil acid content, the acidic compounds are removed after washing with alkalis such as sodium hydroxide, potassium, and sodium carbonate, or with water or a mixture of water and methanol. A method for liquefying coal according to claim 1, characterized in that an acid such as hydrochloric acid, sulfuric acid, or nitric acid is added to the aqueous solution to liberate an acidic compound.