JPS618136A - Catalyst for hydrotreating pitch - Google Patents

Abstract

PURPOSE:To enhance catalytic capacity in the presence of a large amount of tunnel insoluble matter, by supporting metals belonging to the Groups VI-B and VIIIof the Periocid Table being catalyst components and Mo being an essential metal by a fire resistant inorg. oxide carrier. CONSTITUTION:Catalyst components containing Mo as an essential metal and comprising at least one or more of metals belonging to the Groups VI-B and VIIIof the Periodic Table are supported by a carrier comprising fire resistant inorg. oxide such as alumina, silica, boria, zirconiz or titania to mold a catalyst for hydrotreating pitch. The total supporting amount of catalyst metals is 5-35wt% on the basis of oxide and the surface area of the catalyst is 50-300m<2>/g and the pore volume thereof is 0.2-1.0cc/g. The supporting amount of molybdenum is 5-30wt% on the basis of oxide and a combination of supported metals is nickel and molybdenum or cobalt and molybdenum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a catalyst for hydrotreating coal tar pitch. More specifically, the present invention relates to a catalyst for hydrotreating coal tar pitch containing a large amount of toluene insoluble matter. More specifically, it relates to a catalyst that has a long enough life span to enable continuous operation for a long period of time while leaving a large amount of toluene-insoluble matter remaining in the coal tar pitch when mildly hydrotreating the coal tar pitch. It is.

[Prior art] - It is known that coal tar pitch, which is excellent as a raw material for carbon materials such as pitch coke, particularly needle coke and carbon fiber, can be obtained by hydrogenating coal tar pitch. Usually this hydrogenation is mild.

For example, JP-A-59-36,725 describes that pitch is slightly hydrogenated with tetrahydroquinoline or the like in order to produce carbon fibers. In addition, the special public
Publication No. 11.602 describes a method for producing needle coke from coal tar pitch, in which the pitch is hydrotreated, and by performing a mild hydrogenation treatment, it is possible to obtain needle coke of excellent quality. It is described that tar pitch can be obtained. That is, by slightly hydrogenating the raw material coal tar pitch, the polycyclic condensed ring structure remains and the nucleus is partially hydrogenated, and at the same time nitrogen is added.

It is thought that pitch is modified by removing heteroatoms such as sulfur and oxygen.

Problems to be Solved by the Invention When hydrogenating coal tar pitch, the first premise is to maintain the high quality of the product, but even more so in the case of industrial production. The key is to acquire a certain quantity of something over a period of time. In the case of treatment of petroleum-based heavy hydrocarbon oil, and in the case of light hydrotreating, long-term continuous operation (for example, 6 months operation) is rarely a problem. This is due to vanadium, which is the biggest cause of deterioration of catalyst activity in the treatment of petroleum-based heavy hydrocarbon oils.
This is because it depends on the amount of deposited metal such as nickel, and if the hydrogenation treatment is mild, the amount of It attached will not be very large.

However, in the case of hydrogen treatment of coal tar pitch, which is a heavy coal-based content, a completely different problem must be faced even if the hydrogenation treatment is mild. That is, in the case of coal tar pitch, although the amount of heavy metals such as vanadium and nickel is significantly small, the amount of carbonaceous substances such as toluene insoluble matter is extremely large. As anyone skilled in the art would know, these toluene-insoluble components accumulate on the catalyst surface in an extremely short period of time, immediately reducing catalyst activity and becoming an extremely important factor that shortens catalyst life. Become. As a simple solution, it is also conceivable to remove the toluene-insoluble matter in advance prior to the hydrogenation treatment.

However, in raw materials for carbon materials such as needle coke, the presence of this toluene-insoluble content is extremely desirable. In other words, the toluene-insoluble content, which is an essential impediment to catalyst life, is a desirable component for products.

The biggest problem is that it has contradictory properties.

The inventors focused on this problem from the beginning of development,
Many efforts have been made to resolve this issue.

In particular, attention should be paid to the fact that the resolution of this issue should prioritize the quality of the carbon material as a raw material above all else, and maintain the specified hydrotreating function for coal tar pitch containing toluene-insoluble matter. At the same time, we have made extensive research efforts to develop a catalyst that can be operated continuously for a specified period of industrial significance.

As a result, the present inventors have discovered a hydrogenation catalyst that is capable of substantially industrial hydrogenation treatment in the presence of a large amount of toluene-insoluble matter, and have achieved the present invention.

The present invention enables continuous operation for a period of industrial significance while maintaining the specified function for a long period of time when producing a carbon material raw material by mildly hydrogenating coal tar pitch containing a large amount of toluene-insoluble matter. By providing a catalyst, conventional I! This is to make it practically possible to hydrotreat coal tar pitch, which has been considered difficult to do. That is, the present invention provides a hydrotreating catalyst for achieving the above object, which comprises: (a) a refractory inorganic oxide containing Group VIB and II of the periodic table;
(b) contains molybdenum as an essential metal; (0) the total amount of supported metals is 5 to 35% by weight based on the oxide; and (d) ) The surface area of the catalyst is 50 to 3001112/(
1. Pore volume is O05~1. It is characterized by being Occ/s+.

Coal tar pitch, which is the object of the present invention, is a residue obtained by carbonizing or liquefying coal, and in order to be used as a carbon material YFT material, coal tar pitch is insoluble in toluene as a solvent. It refers to a substantially condensed polymeric hydrocarbon-like substance. ) is at least 3% or more, preferably 8% or more, and the upper limit is about 60%. Specifically, softening point 7
There are soft pitches below 0°C, medium pitches around 70° to 85°C, and hard pitches above 85°C.
A soft pitch at about 0°C is preferred. Such pitch can be obtained by controlling the distillation point of oil when distilling coal tar, or by cutting back heavy oil to pitch with a high softening point. Coal tar pitch usually contains several percent of quinoline-soluble matter with an unknown carbon number, but this quinoline-soluble matter may deteriorate the catalyst or reduce the performance of the resulting hydrogenated pitch, so it must be removed in advance. This is desirable.

Incidentally, coal tar pitch having desirable properties as a carbon material raw material basically has a polycyclic condensed structure, has a partially hydrogenated nucleus, has an average molecular weight of 1200 to 500, and has an aromatic index fa. The pitch is 0°80 to 0.65.

Therefore, in order to maintain these properties, the presence of so-called toluene-insoluble components is necessary.

Next, the refractory inorganic oxide referred to in the present invention is not particularly limited, but may be alumina, silica, boria, zirconia, chromia, magnesia, titania, phosphor, etc., or silica-alumina combinations thereof. , aliminaboria, alumina phosphor, silical magnesia, etc. may also be used. More desirable oxides are those containing alumina or silica as a main component, and more preferably those containing alumina, which has a large metal-supporting ability, as a main component.

Next, the catalytic metal component, which is one of the constituent components of the catalyst, is at least one metal selected from the group VIB and group II of the periodic table, that is, molybdenum, chromium, cobalt, nickel, iron, etc. It is. In this case, the condition is that molybdenum is included as an essential metal. This is because molybdenum is essential for achieving long-term stability in the hydrotreating of coal tar pitch, which is the objective of the present invention. Of course, only molybdenum, said refractory no lll5
Although it is within the scope of the present invention to support the compound on a compound,
More desirable combinations of metals include molybdenum and iron group metals, particularly molybdenum and nickel, molybdenum and cobalt, or molybdenum, cobalt and nickel. It is desirable that molybdenum be contained in an amount of 40% by weight or more, preferably 60 to 90% by weight, based on oxides, in the total amount of these catalyst metal components.

These metal components are in a metallic state, metal oxide,
Any state of the metal sulfide is effective, and a part of the metal component may be present in a form bound to the catalyst carrier by ion exchange or the like. However, since the catalytic metal has the highest activity and longest life in the sulfide state, it is preferable to presulfidize the catalyst by a known method before starting the reaction.

The content of these metal components is calculated as oxides,
The amount should be in the range of about 5-35% by weight, based on the total weight of the catalyst. When the metal content is 5% by weight or less as an oxide, the activity of the catalyst is insufficient and coking is likely to occur, resulting in a shortened contact life. If the content is 35% by weight or more, not only will the cost increase, but the surface area of the catalyst will decrease, resulting in a catalyst with insufficient activity. The more preferable content is in the range of 5% to 30% by weight.

The seedling content of molybdenum is thus from 5 to 35% by weight, preferably from about 12 to 25% by weight, calculated as oxide and based on the total weight of the catalyst.

If the amount of molybdenum supported is less than 5% by weight, molybdenum will be supported in a highly dispersed state on the surface of a refractory inorganic oxide, such as alumina, and there will be many exposed portions of alumina on the catalyst surface. Coke precursors such as toluene insolubles easily deposit on exposed alumina surfaces and cause coking.

Furthermore, if the amount of molybdenum supported exceeds 35% by weight, not only will the cost increase, but the surface area of the catalyst will decrease, resulting in a decrease in activity.

Furthermore, when organic sodium is mixed in the coal tar pitch, a phenomenon is observed in which the sodium reacts catalytically and deposits on the catalyst surface, reducing the active surface area. It has been found that by supporting 12% by weight or more, the decrease in activity due to this can be significantly prevented.

In the present invention, the combination of the above-mentioned refractory inorganic oxide and metal component is essential, but in addition to this combination, at least one element selected from the group consisting of silicon oxide, phosphorus oxide, and boron oxide is added. Supporting an oxide has a more effective effect on extending the life of the catalyst, which is the ultimate objective of the present invention. It is thought that these components act on some extremely strong acidic sites on the surface of the refractory inorganic oxide, particularly alumina, to modify the acidity to be suitable for catalytic reactions. These auxiliary catalyst components are present in an amount of about 1 to 15% by weight, preferably 2 to 8% by weight, based on the total weight of the catalyst, calculated as oxides, and are typically contained in the refractory inorganic compound alumina. Prepared in shape.

The combination of these various components is determined by paying attention to the type of raw material coal tar to be subjected to hydrotreating, the expected properties of product quality, etc.

The next important requirement for the catalyst of the present invention is the physical properties of the catalyst. When producing a high-grade carbon material raw material by mildly hydrogenating coal tar pitch, it is important to achieve the specified hydrogenation and removal of hetero elements. It must be able to withstand the problem of significantly shortened catalyst life due to the presence of carbonaceous substances such as carbonaceous substances. Therefore, among physical properties, surface area and pore volume are particularly important factors.

Considering the active surface, the surface area of the catalyst needs to be 50 m2/g or more, and considering the lifetime, it needs to be 3oOII12/g or less. Preferably 100111
2/! II or more and 250 m or less and 210 m or less.

On the other hand, the pore volume should be 0.2 cc/a or more from the viewpoint of maintaining the catalyst life due to the accumulation of coke, etc. On the other hand, from the viewpoint of activity and mechanical strength of the catalyst, the pore volume should be 1.
It should be below 0cc/g'.

Preferably it is 0.3 to 0.7 CC10.

As described above, the significance of the catalyst for hydrotreating coal tar pitch in the presence of toluene-insoluble matter has been described, but the coal tar pitch may further contain organic sodium.

This is because NaOH is added during the distillation operation to prevent equipment corrosion caused by chlorine mixed in the pitch, and this interacts with phenol etc. in the pitch to form organic sodium. generally 10
~100pl) lllll'i! Contains a certain amount of sodium.

What is noteworthy is that the catalyst according to the present invention not only functions as a hydrogenation treatment, but also has an extremely effective effect on removing organic sodium.

That is, the presence of sodium conventionally had a serious problem in that it caused blockage of the catalyst layer during hydrogenation treatment. However, by retaining the volume of the sodium in the organic sodium within the pores of the catalyst, the present catalyst does not substantially block the catalyst layer (in addition, stable operation is achieved while suppressing activity deterioration). In order to achieve this function more effectively, it is desirable that the average pore diameter of the catalyst be between 5o and 250m, and it is also possible to However, it is important that the pore volume be 0.3 cc/a.

If it is less than 50 Å, sodium segregates on the catalyst surface and blocks the pores, preventing the catalyst from reaching the desired life of 1q, and reducing the 2S0
If it is 8 or more, the surface area of the catalyst becomes small and the hydrogenation activity becomes small.

In addition, the reason why the membrane for pores is set to 0.3 cc/g or more is to ensure a sufficient sodium retention capacity.Next, the method for producing the hydrogenation catalyst of the present invention is as described above, In order to obtain the catalytic activity, catalyst life, and mechanical strength, any conventional manufacturing method may be used as long as it can manufacture a catalyst that meets the above-mentioned predetermined requirements. To give a simple example, a commercially available alumina carrier is sprayed with a predetermined amount of ammonium molybdate and nickel sulfate dissolved in ammonia water, left to dry for a predetermined period of time, and then heated in an electric furnace for 50 minutes.
A method of firing at 00 to 600°C for 1 to 4 hours is considered. Alternatively, there is a method in which an alumina carrier is impregnated with an ammonia aqueous solution of ammonium rosemolybdate and cobalt nitrate, and then left to stand, dried, and fired. At this time, boron or phosphorus.

In order to produce a supported catalyst, the above dried product is dissolved in deionized water with orthoboric acid or orthophosphoric acid, and then left to stand, dried, and calcined.

Next, the reaction method in the hydrotreating using the catalyst of the present invention can be a normal flow reaction method such as a fixed bed, moving bed, fluidized bed, or ebullated bed by appropriately selecting the catalyst shape etc. It is possible to do so. Further, the reactant may be supplied to the reaction section from either the upper or lower part of the reactor. In other words, the flow of gas and liquid in the reactor may be parallel flow, upward flow, or downward flow. The shape of the catalyst particles may be granular, spherical, or cylindrical, but in particular, the shape of the catalyst particles may be a hollow cylinder or a non-circular cross section, such as an ellipse, a trilobe, a multilobed leaf, or at least one particle along the length. It is desirable to use an elongated extruded catalyst having a surface with such grooves. When such a modified catalyst is used in a fixed bed, the porosity inside the reactor increases,
This has the effect of not only reducing pressure loss in the catalyst layer, but also significantly relieving clogging of the catalyst layer due to coke deposits between catalyst particles.

Regarding the treatment conditions in the hydrotreating using the catalyst of the present invention, the temperature is 200 to 400'C1, preferably 280°C.
~380℃, hydrogen pressure 30~250kg/cm2, Q
, preferably 50 to 200 kg/cm2.

G1 liquid space 1ff0.1~10hr-', good*shi<ha0゜2~2hr-1, hydrogen to liquid ratio 5oo~2oooNt
/2, preferably 800-150ON°C/1. It is.

Finally, the extent of hydrotreatment using the catalyst of the present invention is
It is a mild type of hydrogenation treatment, and specifically, it is a hydrogenation treatment in which the hydrogenation rate, defined as the difference in the hydrogen to carbon atomic ratio of the raw material pitch and the hydrotreated product, is in the range of 0.05 to 0.35%. .

EXAMPLES Next, the content of the present invention will be explained in more detail based on examples.

Table 1 shows the properties of the coal tar pitch for hydrotreating used in the present examples and comparative examples.

The coal tar pitch is obtained by removing undesirable components such as quinoline-soluble components from the viewpoint of product properties and hydrogenation treatment from crude pitch.

Table 1 Specific properties of raw material coal tar pitch Gravity at20'c 1.23 Viscosity
Degree at 140℃, C, P, 20 soft
Temperature point ℃ 32OC
R''wt% 31.0 Toluene insoluble content wt% 9.2 molecules
Most □ Element analysis c wt% 92.3Hwt%
5.1 N wt% 1.1S
wt% o, 57Na
wtppm 461'lI OCR is the Conradson residual carbon ratio number, and Table 2 shows the properties of the catalysts used in the present examples and comparative examples.

(The following is a blank space), Example 1 A life test was conducted using Catalyst A shown in Table 2, in which molybdenum, nickel, and phosphorus were supported on alumina. The test used a fixed-bed continuous hydrotreater, and the hydrogen partial pressure was 140 k (1/cn2 ・G and LH3V0.3h
r-1, hydrogen to liquid ratio 100ONj2. /l was maintained constant, and the temperature was increased by the amount corresponding to the decrease in activity so as to obtain a hydrogenation rate of 0.18. The operating time, which means the tIX life, is when the reaction temperature is 400 = 'C from the start of operation.
This is the total time until reaching the point. Lifespan 400℃,
The reason for this setting is that if the temperature is higher than this, the thermal decomposition reaction will significantly increase and the yield of coal tar pitch will be reduced, and the deposition of carbonaceous substances on the catalyst layer will be intensified and the catalyst will be severely damaged. This is because deterioration and generation of differential pressure may cause trouble in the device. In this test, the starting temperature was 330°C, and the operation could be carried out without any trouble for about 3900 hours until reaching the upper limit temperature of 400°C. Table 3 shows the properties of the coal tar pitch of the product after light fraction separation.

Table 3 Properties and specific gravity of product coal tar pitch
(at 20℃> 1.2.1
Viscosity (at 140℃) C, P, 218
Softening point 'C81,5CCRv
t% 33.3 Torkon insoluble matter wt% 2.3 molecules
Amount: 303 yuan
Elementary analysis Cwt% 92.3 Hwt% 5.6 N wt% 0.83 S wt% 0.13 Na wtppm 3.0 Aromaticity 0
．． 78 Number of side chain carbons 1.5 Number of aromatic rings 4.0 Number of naphthene rings
2.5 From this Table 3, it can be seen that a high-grade carbon material raw material with appropriate aromaticity and naphthene ring quantity and from which hetero elements have been removed, as seen from element S, is obtained. .

Examples 2 to 7 Catalysts B, C, and C shown in Table 2 were used in the same way as Example 1 [A]
Samples E, F, and G were manufactured and subjected to the same life test as in Example 1 under the same conditions. As a result, the operating time showed good results as shown below. .

Catalyst operating time hrB
4200 C3500 D 3400 E 4000 F 3000 G 3700 Comparative example
A catalyst prepared in the same manner as the catalyst is shown in H in Table 2.

That is, nickel and tungsten are supported on alumina. Using this sample, catalyst life test was carried out in the same manner as in Examples 1 to 7 using the coal tar pitch shown in Table 1. As a result, the driving time was 1.4
It can be seen that 00 hours is significantly short of the 2,000 hours of practical operation time.

Effects of the Invention The hydrotreating catalyst of the present invention not only allows mild hydrotreating of coal tar pitch containing a large amount of toluene-insoluble matter, but also makes pitch excellent as a raw material for carbon materials. It is possible to industrially produce it continuously for a long period of time without any problems. In other words, by employing the catalyst of the present invention, it has become possible to operate the plant for more than 2,000 hours in a substantially industrial manner.

The above effects were completely unexpected from the concept that it would be impossible to maintain long-term operation in heavy oil hydroprocessing that contains a large amount of toluene-insoluble matter. The significance of the present invention can be summed up in this one point.

Patent ratio - Applicant Nippon Steel Chemical Co., Ltd. Chiyoda Corporation

Claims (8)

[Claims] (1) A hydrotreating catalyst for mildly hydrotreating coal tar pitch containing a large amount of toluene-insoluble matter, comprising: (a) a refractory inorganic oxide from Group VIB and Group VIII of the periodic table; (b) contains molybdenum as an essential metal; (c) the total amount of supported metals is 5 to 35% by weight based on oxides; and (d) the surface area of the catalyst is A catalyst for hydrotreating coal tar pitch, characterized in that it has a pore volume of 50 to 300 m^2/g and a pore volume of 0.2 to 1.0 cc/g. (2) The catalyst according to claim 1, wherein the Group VIII metal is an iron group metal. (3) The catalyst according to claim 1, wherein the supported metal is nickel and molybdenum, cobalt and molybdenum, or nickel, cobalt and molybdenum. (4) The catalyst according to any one of claims 1 to 3, wherein the amount of molybdenum supported is 5 to 30% by weight based on the oxide. (5) The catalyst according to claim 1, wherein the refractory inorganic oxide is alumina. (6) The refractory inorganic oxide is at least one selected from the group consisting of silicon oxide, phosphorus oxide, and boron oxide.
The catalyst according to claim 1, which is alumina containing two oxides. (7) The catalyst according to claim 1, wherein the refractory inorganic oxide is silica. (8) The catalyst according to claim 1, wherein the catalyst has a surface area of 100 to 250 m^2/g and a pore volume of 0.3 to 0.7 cc/g.