JPS62192487A - Method for treating coal tar - Google Patents

Abstract

PURPOSE:To improve the hydrocracking efficiency through the prevention of the lowering in catalytic activity, by distilling coal tar in vacuo to obtain a distilled oil having a particular b.p. range and hydrocracking the distilled oil. CONSTITUTION:Coal tar obtd. by carbonization of coal, such as low-temp. tar or high-temp. tar, is distilled in vacuo to separate it into a distilled oil and a distillation residue having a b.p. of 538 deg.C or above. A fraction having a b.p. of 350-538 deg.C out of the distilled oil is hydrocracked in the presence of an iron-base catalyst (e.g., iron ore) at 450-500 deg.C under a hydrogen pressure of 100-200kg/cm<2> for 0.5-2.0hr. The hydrocracking product thus obtd. is distilled in vacuo to separate it into a distilled oil and a distillation residue having a b.p. of 350 deg.C or above. The distillation residue is hydrocracked in the presence of a higher catalyst, such as Ni-Mo, at a reaction temp. of 300-400 deg.C under a hydrogen pressure of 100-200kg/cm<2> for 0.5-2.0hr. The hydrocracking product thus obtd. is distilled in vacuo to separate it into a distilled oil and a distillation residue, followed by circulation of a distilled oil having a b.p. of 350-538 deg.C to the step of hydrogenation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for treating coal tar produced as a by-product from a coke oven.

[Conventional technology]

Table 1 shows typical boiling point ranges and yields for each fraction when coal tar is distilled.

Table 1 According to Table 1, coal tar distillation product 55 has a boiling point of 35.
It is recognized that the pitch is 0°C or higher. Currently, the fractions of coal tar distillation products that are attracting attention as chemical raw materials are the fractions below anthracene oil, which account for 45% of coal tar distillation products. For example, anthracene, which is the main component in anthracene oil, is attracting attention as a high-grade dye or as a raw material for a digesting agent for pulp. Cleaning oil contains methylnaphthalene and dimethylnaphthalene, which are used as they are as heat carriers or solvents, and 2,6-dimethylnaphthalene in particular is attracting attention as a raw material for high-grade plastics.

Furthermore, naphthalene in naphthalene oil is currently a major raw material for organic chemicals, and products made from naphthalene oil include plasticizers, dyes, pharmaceuticals, insect repellents, surfactants, etc., and have a wide range of uses. In addition, the amount used is large, and production is expected to increase in the future.

On the other hand, boiling point 350 after removing fractions up to anthracene oil.
℃ or higher pitch is produced in large amounts from coal tar as described above, but its uses are limited, and currently, the amount of pitch used determines the amount of distillation to anthracene oil.

In order to increase the production amount of distillate oil below anthracene oil, it is necessary to increase the amount of pitch used.

Therefore, the present applicant has previously proposed a method for hydrocracking coal-based heavy oil, as shown in Figure 1, in which coal tar is distilled and the fraction up to anthracene oil is removed from the distillation bottom. proposed.

[Problem that the invention seeks to solve]

However, according to these methods, the distillation bottom contains quinolinous components that tend to precipitate carbonaceous substances, resulting in a significant decrease in catalyst activity, and the catalysts used are limited to iron-based so-called disposable catalysts. Ta.

Catalysts used for hydrogen cracking are generally classified into the aforementioned iron-based disposable catalysts and high-grade catalysts such as Co-Mo p Ni-Mo. When a high-grade catalyst is used, a large amount of medium to light oil is produced and the product properties are excellent, but when quinoline-soluble components are included, the catalyst deactivates quickly and the catalyst life is shortened. However, it is not suitable because the catalyst cost increases and the product becomes expensive. On the other hand, when an iron-based disposable catalyst is used, the product yield and product quality are inferior to those when using a high-grade catalyst, so it is necessary to use a large amount, and the catalyst must also be disposed of after use.

Therefore, the present invention was made in view of the above circumstances, and in order to effectively utilize coal tar, it is intended to effectively utilize pitch, which is a heavy oil component of coal tar and has a boiling point of 350° C. or higher. Therefore, an object of the present invention is to provide a method for efficiently hydrogenolyzing pitch and at the same time increasing the yield of anthracene oil with a boiling point of 350° C. or lower, which is attracting attention as a chemical raw material.

[Means for solving problems]

The first method of the present invention for solving the above problems is to distill coal tar under reduced pressure to separate it into a distillate oil and a distillation residue, and to separate the fraction of the distillate oil with a boiling point of 350 to 538°C. It is characterized by subjecting it to hydrogenolysis.

Further, the second invention method is characterized in that coal tar is distilled under reduced pressure to separate it into a distillate oil and a distillation residue, and that the distillate oil has a boiling point.

Further, in the third invention method, coal tar is distilled under reduced pressure to separate distillate oil and distillation residue, and the distillate oil having a boiling point of 350° C. or higher produced by boiling point cracking of the distillate oil is distilled under reduced pressure. It is characterized by being recycled in the hydrogenation process.

[For production]

In the present invention, since the distillate oil having a boiling point of 350 to 538°C is hydrocracked instead of the vacuum distillation residue of coal tar, there is no reduction in catalyst activity due to quinoline solvent, and therefore the catalyst Usage can be reduced,
Moreover, the hydrocracking efficiency is also improved.

Furthermore, if a hydrogenation step is added prior to hydrocracking, the hydrocracking efficiency is further improved.

Further, if the distillate having a boiling point of 350° C. or higher after hydrocracking is recycled to the hydrogenation process, the product of the hydrocracking process can be converted to a distillate having a boiling point of 350° C. or lower.

[Specific examples of the invention]

The present invention will be explained in more detail below.

As the coal tar in the present invention, low-temperature tar, high-temperature tar, etc. that are produced as a by-product during coal carbonization can be used.

In the present invention, as shown in FIG. 1, when hydrocracking these coal tars, the coal tar is distilled under reduced pressure in advance to separate it into distillate oil and distillation residue, and the boiling point of the distillate oil is Hydrogenolysis is performed on those at 350-538°C. Thereby, the hydrocracking reaction of coal tar proceeds efficiently.

The residue contains a large amount of TI (luene-insoluble matter) and QI (quinoline-soluble matter), which tend to cause a decrease in the activity of the hydrogen cracking catalyst. By removing the distillation residue containing these in advance, a decrease in the activity of the catalyst is significantly suppressed and the life of the catalyst is extended.

As a result, in the case of an iron-based disposable catalyst, the amount of catalyst used is reduced, the proportion of catalyst cost included in the product cost is reduced, and the product can be provided at a low price.

Here, as for the cut point of this distillation residue, the higher the cut point is, the more effectively the distillate can be used, which is preferable, but the upper limit of the boiling point of 538°C for general industrial distillation equipment is recommended.
is restricted to.

Furthermore, the lower limit of the distillate introduced into the hydrocracking step is 350° C., which is the upper limit of the boiling point of coal tar distillation products, at which anthracene oil is distilled. boiling point 3
Introducing light/medium oil at a temperature of 50° C. or lower into the hydrocracking process is not preferable because the hydrocracking reaction of the light/medium oil also proceeds. Thus, the hydrocracking process requires a boiling point of 3
A 50-538°C cut is introduced.

The operating conditions for the hydrocracking process are a reaction temperature of 450 to 500°C.
, hydrogen pressure 100-200 kg/cIn2 or more, reaction time 0.5-2. Oh is desirable.

If the reaction temperature is less than 450° C., although the hydrogenation reaction will proceed, the hydrocracking reaction will be difficult to proceed, and the yield of medium to light oil below the target anthracene oil will be low.

If the reaction temperature exceeds 500° C., the amount of gas by-product is large and coking troubles are likely to occur.

If the hydrogen pressure is less than 100 kg, 41, it is difficult for the hydrogenation reaction of aromatic rings to proceed, and the cracking reaction that follows the hydrogenation reaction is also difficult to proceed, resulting in a low yield of medium and light oil. On the other hand, if the hydrogen pressure becomes too high, the consumption of expensive hydrogen increases and the cost required for pressure-resistant equipment becomes relatively high.

If the reaction time is less than 0.5 h, the hydrocracking reaction will not proceed sufficiently, resulting in a low yield of medium and light oil. Also, the reaction time is 2
If it exceeds hr, the throughput decreases and the hydrocracking reaction cannot proceed efficiently.

The catalyst used in this hydrocracking step is preferably an iron-based catalyst. Under the conditions of high reaction temperature as described above, N
If a high-grade catalyst such as i-Mo is used, even though the distillation residue containing TI and QI has been removed in advance, the hydrogenolysis reaction is likely to occur, producing carbonaceous substances and significantly reducing the activity of the catalyst. It is. As the iron-based catalyst used in the present invention is required in large quantities, readily available and inexpensive red mud is used as the raw material, such as iron ore, waste from steel mills, coal gasifiers, etc. It is desirable to use the sulfur compound as a promoter in an amount of 1 to 10% based on the raw material.The hydrocracking product is separated into distillate oil and distillation residue by atmospheric distillation and vacuum distillation.

The inventors have discovered that the boiling point 3
It has been found that the hydrocracking efficiency in this hydrocracking step is significantly improved by subjecting the 50 to 538° C. fraction to a hydrogenation treatment in advance, as shown in FIG. 2.

Under hydrogenolysis conditions where the reaction temperature is 450° C. or higher, the aromatic compound immediately undergoes a thermal decomposition reaction upon hydrogenation.

Under such conditions, the hydrogen-donating property of the hydrogenated aromatic compound is required in order for the molecular weight reduction reaction to proceed smoothly. Furthermore, hydrogenated aromatic compounds are more easily hydrogenolyzed than aromatic compounds. Therefore, if the hydrogenation treatment is performed prior to the hydrocracking step, the hydrogenated aromatic ring compound can be introduced into the hydrocracking step.

The operating conditions for the hydrogenation step are a reaction temperature of 300 to 400°C;
Hydrogen pressure of 100 to 200 kg/cm2 or more and reaction time of 0.5 to 2 Oh are desirable.

This is because at a reaction temperature of less than 300°C, the hydrogenation reaction does not proceed sufficiently, and at a temperature exceeding 400°C, a hydrogenolysis reaction occurs. If the hydrogen pressure is less than 100◆2, the hydrogenation reaction will not proceed sufficiently. On the other hand, if the hydrogen pressure is too high, the consumption of expensive hydrogen will increase and the cost required for pressure-resistant equipment will also become relatively high. If the reaction time is less than 0.5 h, sufficient hydrogenation reaction will not proceed, and if the reaction time exceeds 2 h, the throughput will decrease.

The catalyst used in this hydrogenation step is preferably a high-grade catalyst such as Ni-Mo. By removing the distillation residue with a boiling point of 538°C or higher in advance, the catalyst is less likely to be deactivated due to carbonaceous precipitation during the hydrogenation process, and the hydrogenation performance is improved compared to iron-based catalysts. This is because it is excellent. As such a high-grade catalyst, Nl-Mo/kt203
e Ni -w/ kL20 s r Co -Mo
/At206 etc. are mentioned.

Furthermore, as shown in Figure 3, the present inventors recycled the distillate oil with a boiling point of 350°C or higher after hydrocracking to the hydrogenation process, thereby converting the product of this hydrocracking process to a boiling point of 350°C or higher. It was discovered that it can be converted into the following distillate oil.

As mentioned above, current coal tar distillation products have a boiling point of 350.
Distilled up to anthracene oil up to ℃, boiling point 350
The market value of distillate oil with a boiling point of 350° C. or higher is not so high, and it is desired to increase the yield of distillate oil with a boiling point of up to 350° C. even in the hydrocracking process. By recycling the hydrocracking distillate having a boiling point of 350° C. or higher to the hydrogenation process, the product of this hydrocracking process can be converted into a product with a boiling point of 350° C. or lower and having high market value.

Incidentally, the equipment for vacuum distillation of hydrocracking products can also be used as the equipment for vacuum distillation of coal tar, thereby reducing the manufacturing cost of this hydrocracking process.

[Embodiments of the invention]

The present invention will be further explained in detail with reference to Examples.

(Example 1) Pitch obtained by removing fractions up to a boiling point of 350'C from coal tar was used as a raw material. The elemental analysis is shown in Table 2.

In Table 2, this pitch was distilled under reduced pressure, and a heavy oil (1) with a boiling point of up to 538° C. obtained at a yield of 60 inches based on the pitch was used as a raw material for hydrocracking. The analytical values for heavy oil ■ are shown in Table 3.

Table 3 This heavy oil (■) was hydrocracked using a hydrocracker having a processing capacity of 0.51 h according to the flow shown in Fig. 1 and under the operating conditions shown in Table 4.

Table 4 After separating the gaseous products, the hydrogenolysis products were separated into various fractions by atmospheric distillation and vacuum distillation.

The material balance in this hydrogenolysis reaction is shown in Table 5 as an example. As comparative examples, the results of hydrocracking without catalyst (Comparative Example 1) and the results of using the distillation residue after hydrocracking as a catalyst (IP Example 2) are shown.

Table 5 From Table 5, heavy oil in the presence of a catalyst compared to when no catalyst
It is recognized that the weight reduction of the fuel is promoted.

In addition, high lightening activity is still observed in the distillation residue after hydrocracking.

Table 6 shows the results of Table 5 at pitch pace as an example, and the results of hydrogenolysis of Bi and Te according to the flow of FIG. 1 as a conventional example.

Table 6 From Table 6, it can be seen that the conventional example and the example have almost the same hydrogenolysis results.

When hydrocracking pitch using a hydrocracker of the same capacity, in the example in which distillation residue with a boiling point of 538°C or higher is removed in advance, the throughput can be approximately twice as much as in the comparative example. It is of great significance from the viewpoint of hydrocracking efficiency to remove the distillation residue having a boiling point of 538° C. or higher in advance.

In addition, the distillation residue that has been removed in advance by vacuum distillation contains almost no ash and is suitable as a raw material for carbon materials, but the distillation residue produced by hydrocracking pitch is used as a catalyst. If the raw material for carbon material contains iron-based compounds, it is necessary to take measures to remove the iron-based compounds.

(Example 2) The heavy oil was hydrogenated according to the flow shown in FIG. 2 prior to hydrocracking.

For hydrogenation, a hydrogenation apparatus having a processing capacity of 9.5 to 9/hr was used under the operating conditions shown in Table 7.

After separating the gaseous products, the hydrogenated product was subjected to atmospheric distillation and reduced pressure distillation.

Table 8 shows the material balance of this hydrogenation reaction.

Table 7 Table 8 Table 9 shows the analytical values of heavy oil (1), which was used as a raw material for the following hydrocracking using the boiling point 350-538°C fraction obtained by hydrogenation as heavy oil (1).

Table 9 Compared to the heavy oil shown in Table 3, the hydrogen content has increased,
It is observed that the aromatic carbon fraction (fa) has decreased.

This heavy oil (■) was hydrocracked in the same manner as heavy oil, and the material balance was shown as Example 2 together with the material balance of the hydrogenation process, and compared with the results of hydrocracking of heavy oil (2). It is shown in Table 10.

Table 10 From Table 10, it is recognized that the product can be made lighter by performing hydrogenation prior to hydrocracking.

(Example 3) Table 11 shows the material balance when the boiling point 350-538°C fraction after hydrogenolysis in Example 2 is circulated to the hydrogenation process according to the flow shown in Figure 3 and reaches steady state. This is shown as Example 3.

Further, as a comparative example, a material balance is shown as Comparative Example 3 in the case where a fraction with a boiling point of 350 to 538°C produced by hydrocracking heavy oil as a raw material is recycled to the hydrocracking process again.

It is observed that in both Example 3 and Comparative Example 3 in Table 11, the product consists of a medium/light oil below anthracene oil and a distillation residue with a boiling point of 538° C. or above.

It is observed that in Example 3, compared to Comparative Example 3, the amount of distillation residue produced with a bp of 538°C or higher and the amount of circulation with a bp of 350-538°C were small, and the amount of light and medium oils below anthracene oil was large.

If there is a large amount of circulating bp350-538℃ fraction, the processing amount of the raw material bp350-538℃ fraction will decrease.
It is desirable to reduce the amount of circulation. Also from this point of view, it is significant to install a hydrogenation process prior to the hydrocracking process. Furthermore, the installation of a hydrogenation process is of great significance due to the increased production of medium and light oils below anthracene oil.

Additionally, the product of this hydrocracking process is gas.

In addition to water, medium and light oils below anthracene oil with a boiling point of 538℃
The above distillation residue is the main product, and the main products are medium to light oils below anthracene oil. Boiling point after hydrocracking process 350-
538. By recycling the °C fraction back to the hydrogenation process, the product of this hydrocracking process can be converted into a product with high market value.

Table 12 shows the results of recalculating Examples t and 2t3 according to the present invention based on the coal tar pace, and Comparative Example 4 shows the distribution of coal tar distillation products. bp350- in tar
It is recognized that this is an effective means for reducing the 538°C fraction and increasing the amount of ant-2-sene oil.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent a decrease in catalyst activity, reduce catalyst cost, and improve hydrocracking efficiency.

[Brief explanation of drawings]

1 to 3 are schematic process diagrams of the method of the present invention, and FIG. 4 is a process diagram of a conventional example. 1st ■ Figure

Claims (3)

[Claims] (1) Coal tar is distilled under reduced pressure to separate distillate oil and distillation residue, and among the distillate oil, boiling point 350-5
A method for treating coal tar, which comprises performing hydrogenolysis on a distillate fraction at 38°C. (2) Coal tar is distilled under reduced pressure to separate distillate oil and distillation residue, and among the distillate oil, boiling point 350-5
A method for treating coal tar, which comprises subjecting the distillate at 38° C. to hydrogen treatment, and then subjecting the distillation bottom obtained by distillation under reduced pressure to hydrogenolysis. (3) Coal tar is distilled under reduced pressure to separate distillate oil and distillation residue, and among the distillate oil, boiling point 350-5
Hydrotreating the distillate at 38°C, then hydrocracking the distillation bottoms obtained by distillation under reduced pressure, and recycling the distillate oil with a boiling point of 350°C or higher produced by this hydrocracking to the hydrogenation step. A method for processing coal tar characterized by the following.