JPH09263775A - Production of heavy oil base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low sulfur heavy oil base material economically without causing the plugging of pipes downstream of a hydrogenation tower by hydrotreating a specified feedstock oil repeatedly under specified conditions to form a hydrotreated oil. SOLUTION: A feedstock oil (e.g. vacuum residue) having a dry sludge content of 0-5.0mass% and an S content of 1.0-10mass% is hydrotreated in the 1st-stage tower packed with a hydrogenation catalyst (e.g. a catalyst prepared by impregnating an alumina support with NiO and MoO3 ) under elevated pressure at a temperature (the maximum temperature in the catalyst bed) of 390-450 deg.C to obtain a hydrotreated oil having an S content which is at most 30% of that of the feedstock oil and a content (T) of toluene-insolubles of 10 mass ppm or above. This oil is hydrotreated in the 2nd-stage hydrotreatment tower packed with a hydrogenation catalyst under elevated pressure at a temperature (the maximum temperature in the catalyst bed) which is lower than that in the 1st-stage tower by at least 10 deg.C and is lower than 410 deg.C to obtain a hydrotreated oil having an S content of 30% or below and a T which is at most 50% of that of the hydrotreated oil obtained in the 1st stage.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a heavy oil base stock.

[0002]

2. Description of the Related Art Conventionally, heavy oil in Japan has a low sulfur-containing atmospheric distillation residue obtained by removing crude hydrocarbons such as naphtha, kerosene and light oil by treating crude oil having a low sulfur content with an atmospheric distillation apparatus. And a low-sulfur vacuum distillation residue obtained by further treating the low-sulfur atmospheric distillation residue with a reduced-pressure distillation apparatus to remove reduced-pressure gas oil. It has been manufactured by mixing kerosene, light oil, etc. in the adjustment of.

[0003] On the other hand, low supply of low-sulfur crude oil, effective utilization of atmospheric or reduced-pressure distillation residue obtained from crude oil having a high sulfur content, and increase in production of middle distillates such as kerosene and gas oil for viscosity adjustment. From low-sulfur and low-viscosity by contacting the atmospheric or reduced pressure distillation residue obtained from crude oil with high sulfur content with a hydrogenation catalyst under high temperature and high hydrogen partial pressure to promote desulfurization, denitrification and cracking reaction Hydroprocessing processes to produce heavy oil bases have been developed and are in commercial operation. Typical operating conditions for this hydrotreating process are a reaction temperature of 350
~ 450 ° C, hydrogen partial pressure 9.8 ~ 19.6M at the inlet of the reaction tower
Pa, liquid space velocity 0.1 to 5.0 h ^-1 , and hydrogen / oil ratio of 250 to 1700 Nm ³ / m ³ at the inlet of the reaction tower.

As described above, these hydrotreating processes effectively utilize the atmospheric pressure or reduced pressure distillation residue obtained from a low-sulfur crude oil supply shortage or a crude oil having a high sulfur content, and further kerosene or light oil for viscosity adjustment. It is very significant from the viewpoint of increasing the production of middle distillates, etc., but when the distillation residue is hydrotreated under severe operating conditions such as increasing the reaction temperature, the heavy products in the product will be As a result, the quality of coke increases and adheres to the surface of a tube such as a heat exchanger downstream of the reactor, which may cause an increase in pressure loss and eventually blockage of the tube. Increased pressure loss results in significant losses because the entire system must be shut down to clean the tubes.

Therefore, until now, in the operation of the hydrotreating process, there was no choice but to be restricted by the operating conditions such that the upper limit is the reaction temperature that does not cause an increase in the pressure loss of the downstream pipe.

[0006] Further, the hydrogenation catalyst used in the hydrotreatment of the distillation residue usually decreases in activity of desulfurization, denitrification, and decomposition reaction with the operation time, so that it is necessary to compensate for the decrease in catalyst activity during operation. The reaction temperature at the initial stage of operation is determined in consideration of the increase in the reaction temperature, but the catalytic activity decreases due to changes in the type of feed oil represented by crude oil type during operation and changes in the target value of the sulfur content of produced oil. May go beyond expectations and reach the design reaction temperature at the end of operation during operation.

Therefore, even if the reaction temperature in the initial stage of operation is set to a temperature below the temperature at which the pressure loss in the downstream pipe does not increase, if the design reaction temperature in the final stage of operation is reached during the operation, the pressure loss in the downstream pipe will increase. Therefore, after that, the conversion rate of desulfurization, denitrification, and decomposition reactions is reduced, and the treatment rate of the vacuum distillation residue, which requires severe reaction conditions, is reduced.
Alternatively, there has been a limitation that only the atmospheric distillation residue under mild reaction conditions is treated, or the treatment amount is reduced.

[0008]

DISCLOSURE OF THE INVENTION The present invention uses a feed oil having a relatively high sulfur content obtained from an atmospheric distillation apparatus or a vacuum distillation apparatus without causing clogging of a pipe downstream of a hydrogenation reaction column. An object of the present invention is to provide a method for economically producing a heavy oil base material having a low sulfur content.

[0009]

[Means for Solving the Problems] When hydrotreating the atmospheric distillation residue or vacuum distillation residue obtained from crude oil having a high sulfur content as described above under high operating conditions such as increasing reaction temperature, Heavy components and coke in the produced oil may increase and adhere to the surface of tubes such as heat exchangers downstream of the reactor to increase pressure loss and eventually to block the tubes. As the causative substance that causes such pipe blockage, it is considered that the heavy components in the feedstock are polymerized, or the polycyclic aromatic compounds such as asphaltene that have lost the aliphatic side chain and have higher aromaticity. To be The present inventors further studied the causative substances causing the above-mentioned tube clogging, and found that there was a good correlation between the toluene insoluble content and the increase in the pressure loss of the tube. And the present inventors have conducted research to solve the above-mentioned problems that occur when a petroleum distillation residue having a relatively high sulfur content is hydrotreated under severe conditions to obtain a heavy oil base material having a low sulfur content. As a result of repeated experiments, it was found that a heavy oil base material having a low sulfur content and a toluene insoluble content content can be obtained by hydrotreating a feed oil in two stages under specified conditions, and the present invention was completed. It was

The present invention has a dry sludge content of 0 to
In the first stage in which a feed oil having a sulfur content of 5.0% by mass and a sulfur content of 1.0 to 10% by mass was filled with a hydrogenation catalyst, hydrogen was added under pressure at a maximum temperature in the catalyst bed of 390 to 450 ° C. To obtain a hydrotreated oil having a sulfur content of 30% or less of the sulfur content of the raw material oil and a toluene insoluble content of 10 mass ppm or more, and then continuously treating the hydrotreated oil of the first stage with hydrogen. In the second stage filled with the hydrogenation catalyst, the maximum temperature in the catalyst bed is 10 ° C. or more lower than the maximum temperature in the first stage under pressure, and the hydrotreating process is performed at 410 ° C. or less, so that the sulfur content is higher than that of the feed oil. To obtain a hydrotreated oil having a sulfur content of 30% or less and a toluene insoluble content of 50% or less of the toluene insoluble content of the first stage. Is. Hereinafter, the contents of the present invention will be described in detail.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Specific examples of the feedstock in the method for producing a heavy oil base material of the present invention include petroleum distillation residue. Specific examples of these petroleum distillation residues include, for example, 70% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass of a fraction obtained at a distillation temperature of 300 ° C. or higher, which is obtained from an atmospheric distillation apparatus. Atmospheric pressure distillation residue containing at least mass%; reduced pressure containing a fraction obtained at a distillation temperature of 400 ° C. or more, usually 70 mass% or more, preferably 90 mass% or more, more preferably 95 mass% or more, obtained from a vacuum distillation apparatus. Distillation residue; Residue oil obtained by mixing these atmospheric distillation residue and vacuum distillation residue at any ratio; Hydrogenation of these atmospheric distillation residue, vacuum distillation residue or mixture thereof The product oil obtained by reducing the sulfur content, the nitrogen content, and the like; or a mixture of these.

The distillation temperature in the present invention means JIS
"Petroleum products-Distillation test method" specified in K 2254
Means the temperature measured in accordance with “6. Hereinafter, the distillation temperature of the petroleum fraction in the present invention means a value measured by the above method.

Further, as the feedstock of the present invention, the catalytic cracking unit (FC
A cracked heavy oil (heavy cycle oil) obtained from C) or a mixed oil obtained by mixing 40 parts by weight or less, preferably 20 parts by weight or less of a slurry oil can also be preferably used.

Further, as the feedstock of the present invention, a part of the outlet oil in the second-stage hydrotreating step described later is recycled to obtain 100 parts by weight of the above petroleum distillation residue or mixed oil. A mixed oil containing 50 parts by weight or less, preferably 30 parts by weight or less of recycled oil can also be preferably used.

The dry sludge in the present invention is a solid particle in oil mainly composed of asphaltene molecules having a diameter of 1.0 μm or more. The lower limit of the dry sludge content of the feedstock in the present invention is 0% by mass, while the upper limit thereof is 5.0% by mass, preferably 1.0% by mass. If the upper limit of the dry sludge content exceeds 5.0% by mass, the strainer or valve in the feedstock feed system in the hydrotreating process is blocked, and the heat transfer efficiency is reduced due to fouling of the heat exchanger or heating furnace. This is not preferable because it may cause the problem described above.

The dry sludge content in the present invention means "Standard Test Meth" defined in ASTM D 4870-92.
od for Determination of Total Sediment in Residual
It means the total amount of sediment measured according to Fuels ”.
Hereinafter, the dry sludge content in the present invention means a value measured by this method.

The lower limit of the sulfur content of the petroleum distillation residue is 1.0% by mass, preferably 2.0% by mass,
On the other hand, the upper limit value is 10% by mass, preferably 6.0% by mass. When the sulfur content is less than 1.0% by mass, it is possible to manufacture a heavy oil base without the need for hydrotreatment in a two-stage process as in the present invention, which is disadvantageous in energy cost. is there. Further, when the sulfur content exceeds 10% by mass, the sulfur content of the obtained heavy oil base material becomes high, and when used as a boiler fuel, the amount of sulfur oxides in the combustion exhaust gas increases. Further, in order to further reduce the sulfur content of the obtained heavy oil base material, the construction cost of the reaction tower, peripheral equipment and the like rapidly increases, and a large amount of cutter material is required.

The sulfur content in the present invention means JI
It means the sulfur content measured according to “6. Radiation excitation method” of “Crude oil and petroleum products-Sulfur content test method” specified in SK 2541-1992. Hereinafter, the sulfur content in the present invention means all values measured by the above method.

In the present invention, these feedstock oils are first subjected to hydrotreating under pressure and temperature rise in the first stage in which the hydrogenation catalyst is filled. The lower limit of the temperature in the catalyst bed of the first stage is preferably 340 ° C. or higher, more preferably 37
0 ° C. or higher, on the other hand, the upper limit thereof is preferably 450
C., more preferably 430.degree. Further, in the present invention, the maximum temperature in the first stage catalyst bed has a lower limit value of 390 ° C. or higher, preferably 400 ° C. or higher, while its upper limit value is 45 ° C. or higher.
It should be maintained at 0 ° C, preferably 430 ° C. When the lower limit of the temperature in the catalyst bed of the first stage is less than 340 ° C or the maximum temperature is less than 390 ° C, the catalytic activity is not sufficiently exhibited, so desulfurization, denitrification and decomposition reactions do not proceed to the practical range. However, if the hydrotreating temperature exceeds 450 ° C., the coking reaction becomes vigorous, coke is deposited on the catalyst, the catalytic activity is rapidly reduced, and the catalyst life is shortened, which is not preferable. The maximum temperature in the catalyst bed in the present invention refers to the temperature of the highest temperature in the catalyst bed when the catalyst bed has a temperature gradient with respect to the flow direction of the feed oil, when the catalyst bed is an isothermal system Refers to the average temperature of the catalyst bed. The conditions other than the temperature in the first stage hydrotreatment process are arbitrary.

The hydrogen partial pressure of the inlet in the first stage is usually such that the lower limit value is preferably 8.0 MPa, more preferably 9.8 MPa, while the upper limit value is preferably 25.
The range is 0 MPa, and more preferably 19.6 MPa. If the hydrogen partial pressure is less than 8.0 MPa, there is a concern that coke formation on the catalyst will become violent and the life of the catalyst will be extremely shortened. On the other hand, if the hydrogen partial pressure exceeds 25.0 MPa, the reaction tower, peripheral equipment, etc. There is a concern that the construction cost of the project will rise sharply, and its economic utility will be lost.

Liquid hourly space velocity (LHS) of the feedstock in the first stage
V) is normally the lower limit of preferably 0.05 h ^-1, more preferably 0.1 h ^-1, whereas the upper limit is preferably from 5.0 h ^-1, more preferably 2.0 h ^-1 It is a range. When the liquid hourly space velocity (LHSV) is less than 0.05 h ^-1 , there is a concern that the construction cost of the reaction tower becomes enormous and economically impractical. On the other hand, the liquid hourly space velocity (LHSV) is 5.
If it exceeds ⁰ h ^-1 , there is a concern that the catalytic activity will not be sufficiently exhibited and that desulfurization, denitrification and decomposition reactions will not proceed to the practical range.

The hydrogen / oil ratio at the inlet of the first stage, usually, the lower limit is preferably 250 Nm ³ / m ^3, more preferably from 600 Nm ³ / m ^3, whereas the upper limit is preferably 1700 nm ³ / m ³ , more preferably 1500 Nm ³
The range is / m ³ . Hydrogen / oil ratio of 250 Nm ³ / m ³
If it is less than the above, coke formation on the catalyst may become severe and the life of the catalyst may be extremely shortened, while the hydrogen / oil ratio may be 17 or less.
If it exceeds 00 Nm ³ / m ³ , there is a concern that the construction cost of the reaction tower, peripheral equipment and the like will rise sharply, and economically impractical.

The hydrotreating operation in the first stage can be carried out in parallel with oil and gas in a downflow or upflow, or can be carried out with oil and gas in countercurrent. Further, the reaction tower used by being filled with a catalyst for the first-stage hydrotreatment may be either a single reaction tower or a plurality of continuous reaction towers. Further, the inside of the reaction tower may be constituted by either a single catalyst bed or a plurality of catalyst beds.

A gas, a liquid, or a mixture of liquid and gas is used between the reaction towers in the first stage hydrotreatment or between the catalyst beds for the purpose of adjusting the reaction temperature at the inlet of the subsequent reaction tower or catalyst bed. It is also possible to inject.

The gas referred to herein is usually hydrogen; for example, methane, ethane, propane, butane, pentane, hexane, and other paraffinic hydrocarbons having 1 to 6 carbon atoms, and mixtures thereof. Is preferably used, but a mixture of hydrogen and these hydrocarbons is preferably used, but it may contain other substances such as hydrogen sulfide, ammonia, and nitrogen, which can exist as a gas at the temperature and pressure of injection. .

The liquid referred to here is usually, for example,
Petroleum distillates such as kerosene, straight-run gas oil and vacuum gas oil; petroleum distillation residues; hydrotreated oils such as petroleum distillates and petroleum distillation residues; pyrolysis oils such as petroleum distillates and petroleum distillation residues Hydrocarbons that can be present as a liquid at the temperature and pressure of injection, such as catalytically cracked oils such as petroleum distillates and petroleum distillation residues; or mixtures thereof, are preferably used, but the second stage hydrotreatment described below. It is more preferable to recycle and use a part of the outlet oil in the process.

When gas or liquid is injected between the reaction towers or between the catalyst beds in the first stage, the injection amount thereof is arbitrary, but when the gas is injected, the injection amount is usually gas / oil ratio. Can be performed in the range of 1700 Nm ³ / m ³ or less. When injecting a liquid, the injection amount is 1 m in terms of liquid / oil ratio.
³ / m ³ or less.

When a plurality of reaction towers or catalyst beds are used in the first stage hydrotreating step, the maximum temperature in the catalyst bed in the present invention means the gas between the reaction towers and the catalyst beds. , With or without injection of a liquid or a mixture of liquid and gas, and further regardless of the number of reaction columns,
For all catalyst beds of the first stage, it refers to the temperature at the highest temperature.

As the hydrotreating catalyst in the first stage hydrotreating step, any conventionally known hydrotreating catalyst can be used. Specifically, for example, alumina,
Silica, titania, zirconia, magnesia, alumina-silica, alumina-boria, alumina-titania, alumina-zirconia, alumina-magnesia, alumina-silica-zirconia, alumina-silica-titania,
A porous inorganic oxide such as various zeolites, sepiolite, various clay minerals such as montmorillonite, which is used as a carrier, and a hydrogenation-active metal is supported thereon can be preferably used.

The metal to be supported is usually V
At least one hydrogenation-active metal species selected from the group IA, VA, VB, and VIII metals is preferably used. In particular, cobalt, molybdenum, and nickel are each used alone, or two or more of cobalt, molybdenum, and nickel are used. A catalyst supported on a porous inorganic oxide in combination of three types is more preferably used. The hydrotreating catalyst used in the hydrotreating step of the first stage of the present invention can be achieved even if it is a commercially available hydrotreating catalyst, and the present invention is not limited by the kind of the catalyst. Not a thing.

The content of toluene-insoluble matter in the hydrotreated oil obtained in the first stage hydrotreatment is 10 mass ppm or more. More generally, the value is 20 mass ppm or more.
In the present invention, the toluene insoluble component refers to a component insoluble in toluene in the sample, and the content of the toluene insoluble component is represented by a weight ratio between the component insoluble in the sample and the sample. Examples of the method for measuring the content of toluene insolubles include a method in which an appropriate amount of a sample is dissolved in sufficient toluene, filtered with a filter having a sufficiently fine mesh, and the mass of the filter cake on the filter is measured. In this method, a sample of 50 to 150 g is usually used, and this is dissolved in toluene to make a total amount of 500 to 1
After adjusting to 500 cc, it is filtered with a filter. The filter preferably has a pore size of 0.2 μm or less. The material of the filter is arbitrary as long as it is not changed by the sample or toluene, and a membrane filter or the like is used.

In the first-stage hydrotreatment, substantially all of the desulfurization reaction, denitrification reaction and cracking reaction of the feedstock are substantially achieved. The sulfur content of the hydrotreated oil obtained by the first stage hydrotreatment is 30% or less, preferably 20% or less, of the sulfur content in the raw material. Desulfurization rate is 70
% Or more, preferably 80% or more. Usually, the lower limit of the sulfur content in the feed oil is 0.01% by mass, preferably 0.1% by mass, while the upper limit thereof is 2.0% by mass, preferably 1.0% by mass. . Although the nitrogen content of the hydrotreated oil obtained in the first stage hydrotreatment step is not specified at all, the lower limit thereof is preferably 0.01% by mass, more preferably 0.1% by mass, On the other hand, the upper limit thereof is preferably 1.0% by mass, more preferably 0.
5% by weight is common.

The nitrogen content in the present invention means JI
It means the nitrogen content measured according to "7. Chemiluminescence method" of "Crude oil and petroleum products-Nitrogen content test method" specified in SK 2609-1990. Hereinafter, the nitrogen content in the present invention means all values measured by the above method.

In the present invention, the hydrotreated oil of the first stage is subjected to the hydrotreatment under pressure and temperature rise in the second stage in which the hydrotreated catalyst is further filled. The lower limit of the temperature in the catalyst bed in the second stage is preferably 150 ° C., more preferably 200 ° C.
On the other hand, the upper limit thereof is preferably 410 ° C, more preferably 400 ° C. When the temperature of the catalyst bed in the second stage is lower than 150 ° C., the catalytic activity is not sufficiently exhibited, and the hydrogenation reaction of the toluene insoluble matter does not proceed to a practical range. On the other hand, if the hydrogenation temperature exceeds 410 ° C., the hydrogenation of the toluene-insoluble matter will not proceed, and the toluene-insoluble matter will increase, which is not preferable.

Further, in the present invention, in the second stage hydrogenation, it is important to set the maximum temperature in the catalyst bed to a value lower than the maximum temperature in the first stage catalyst bed to carry out the hydrotreatment. . The maximum temperature in the catalyst bed of the second stage should be kept 10 ° C. or more lower than the maximum temperature in the catalyst bed of the first stage, more preferably 20 ° C. or more lower. In the present invention, when the maximum temperature of the second stage is the same as the maximum temperature of the first stage or higher than the hydrotreating temperature of the first stage, the hydrogenation of the toluene insoluble matter does not proceed, and conversely, the toluene insoluble matter is It is not preferable because it increases.

The conditions other than the temperature in the second stage hydrotreatment are arbitrary. The pressure at the catalyst bed inlet in the second stage is a hydrogen partial pressure, and the lower limit is usually preferably 1.0.
MPa, while the upper limit is preferably 25.0MP
a, more preferably in the range of 19.6 MPa. If the hydrogen partial pressure at the catalyst bed inlet is less than 1.0 MPa, the catalytic activity may not be sufficiently exhibited, and the hydrogenation reaction of the toluene insoluble matter may not proceed to a practical range. If it exceeds 0.0 MPa, the construction cost of the reaction tower, peripheral equipment, and the like will rise sharply, and there is a concern that it will be economically impractical.

The liquid hourly space velocity (LHSV) of the feedstock in the second stage (hydrotreated oil after the first stage hydrotreatment) is
Usually, the lower limit is preferably 0.1 ^-1 , more preferably 0.2 h ^-1 , while the upper limit is preferably 10 1.
h ^-1, more preferably in the range of 4.0 h ^-1. When the liquid hourly space velocity (LHSV) is less than 0.1 h ^-1 , there is a concern that the construction cost of the reaction tower becomes enormous and economically impractical. On the other hand, the liquid hourly space velocity (LHSV) is 10 h ^-1. If it exceeds, the catalytic activity may not be sufficiently exhibited, and there is a concern that the hydrogenation reaction of the toluene-insoluble portion may not proceed to a practical range.

The hydrogen / oil ratio at the inlet of the second stage, usually, the lower limit is preferably 250 Nm ³ / m ^3, more preferably from 600 Nm ³ / m ^3, whereas the upper limit is preferably 1700 nm ³ / m ³ , more preferably 1500 Nm ³
The range is / m ³ . Hydrogen / oil ratio of 250 Nm ³ / m ³
If it is less than 1, there is a concern that coke formation on the catalyst will become severe and the life of the catalyst will be extremely short, while the hydrogen / oil ratio will be 1
If it exceeds 700 Nm ³ / m ³ , there is a concern that the construction cost of the reaction tower, peripheral equipment, etc. will rise sharply, and economically impractical.

The operation of hydrotreating in the second stage can be carried out in parallel with oil and gas in a downflow or upflow, or can be carried out with oil and gas in countercurrent. Further, the reaction tower used by being filled with a catalyst in the second stage hydrotreating step may be composed of either a single reaction tower or a plurality of continuous reaction towers. Further, the inside of the reaction tower may be constituted by either a single catalyst bed or a plurality of catalyst beds.

A gas, a liquid or a mixture of liquid and gas is used between the reaction columns in the second stage hydrotreatment or between the catalyst beds for the purpose of controlling the reaction temperature at the inlet of the subsequent reaction column or catalyst bed. It is also possible to inject.

The gas referred to herein is usually hydrogen; for example, methane, ethane, propane, butane, pentane, hexane, and other paraffinic hydrocarbons having 1 to 6 carbon atoms, and mixtures thereof. Is preferably used, but a mixture of hydrogen and these hydrocarbons is preferably used, but it may contain other substances such as hydrogen sulfide, ammonia, and nitrogen, which can exist as a gas at the temperature and pressure of injection. .

The liquid mentioned here is usually, for example,
Petroleum distillates such as kerosene, straight-run gas oil and vacuum gas oil; petroleum distillation residues; hydrotreated oils such as petroleum distillates and petroleum distillation residues; pyrolysis oils such as petroleum distillates and petroleum distillation residues Hydrocarbons that can be present as a liquid at the temperature and pressure of injection, such as catalytically cracked oils such as petroleum distillates and petroleum distillation residues; or mixtures thereof, are preferably used, but in the second stage hydrotreatment step It is more preferable to recycle a part of the outlet oil for use.

When injecting a gas or a liquid between the reaction towers or between the catalyst beds in the second stage, the injection amounts are arbitrary, but when injecting the gas, the injection amount is usually the gas / oil ratio. Can be performed in the range of 1700 Nm ³ / m ³ or less. When injecting a liquid, the injection amount is 1 m in terms of liquid / oil ratio.
³ / m ³ or less.

When a plurality of reaction towers or catalyst beds are used in the second stage hydrotreatment, the maximum temperature in the catalyst bed in the present invention means the gas, liquid or gas between the reaction towers and the catalyst beds. It refers to the temperature of the highest temperature for all catalyst beds of the second stage, with or without injection of a mixture of liquid and gas, and also regardless of the number of reaction columns.

As the hydrotreating catalyst used in the second stage hydrotreating, any conventionally known hydrotreating catalyst can be used. Specifically, for example, alumina, silica, titania, zirconia, magnesia, alumina-silica,
Alumina-Boria, Alumina-Titania, Alumina-Zirconia, Alumina-Magnesia, Alumina-Silica-
Porous inorganic oxides such as zirconia, alumina-silica-titania, various zeolites, various clay minerals such as sepiolite and montmorillonite are used as a carrier, and a substance having a hydrogenation-active metal supported thereon can be preferably used.

As the supported metal, usually, the periodic table V
At least one hydrogenation-active metal species selected from the group IA, VA, VB, and VIII metals is preferably used. In particular, cobalt, molybdenum, and nickel are each used alone, or two or more of cobalt, molybdenum, and nickel are used. A catalyst supported on a porous inorganic oxide in combination of three types is more preferably used. The hydrotreating catalyst used in the hydrotreating step of the second step of the present invention can be achieved by using a commercially available hydrotreating catalyst, and the present invention is not limited by the kind of the catalyst. Not a thing.

In the present invention, the first stage and second stage hydrotreating may be carried out in one reaction tower or may be carried out using two or more separated reaction towers.
Further, the inside of the reaction tower may be divided into a plurality of catalyst beds.

In the present invention, the method of lowering the second stage hydrotreating temperature below the first stage hydrotreating temperature is not particularly limited, and any method can be adopted. Specifically, a conventionally known method, for example, a low temperature gas,
A method of injecting a liquid, or both a gas and a liquid, a method of heat exchange with a cryogenic fluid by a heat exchanger, or the like can be used.

The gas referred to herein is usually hydrogen; for example, methane, ethane, propane, butane, pentane, hexane, and other paraffinic hydrocarbons having 1 to 6 carbon atoms, and mixtures thereof at the temperature and pressure for injection. Hydrocarbons that can exist as a gas; or a mixture of hydrogen and these hydrocarbons; are preferably used, but may also contain other substances that can exist as a gas at the injection temperature and pressure, such as hydrogen sulfide, ammonia, and nitrogen. Good.

The liquid referred to here is usually, for example,
Petroleum distillates such as kerosene, straight-run gas oil and vacuum gas oil; petroleum distillation residues; hydrotreated oils such as petroleum distillates and petroleum distillation residues; pyrolysis oils such as petroleum distillates and petroleum distillation residues Hydrocarbons that can be present as a liquid at the temperature and pressure of injection, such as catalytically cracked oils such as petroleum distillates and petroleum distillation residues; or mixtures thereof, are preferably used, but in the second stage hydrotreatment step It is more preferable to recycle a part of the outlet oil for use.

The first-stage hydrotreatment and the second-stage hydrotreatment in the present invention are not limited to the continuous operation, and the first-stage operation and the second-stage operation are carried out individually. Good. When the operations in both stages are individually performed, the conditions between the first stage and the second stage are not particularly limited.

The sulfur content of the hydrotreated oil obtained in the second stage hydrotreatment is 30% or less of the sulfur content in the raw material,
It is preferably 20% or less. The desulfurization rate is 70% or more, preferably 80% or more. Usually, the lower limit of the sulfur content in the feed oil is 0.01% by mass, preferably 0.1%.
On the other hand, the upper limit is 2.0% by mass, preferably 1.0% by mass. The toluene insoluble content is 50% or less, preferably 40% or less, of the toluene insoluble content at the outlet of the first stage hydrotreatment process. As described above, in the present invention, by the above-described two-stage hydrotreatment, heavy oil having a low toluene-insoluble content and a low sulfur content despite the high-temperature treatment in the first-stage hydrotreatment process A substrate is obtained.

The achievement rate of the desulfurization reaction in the present invention means the value represented by the following formula 1. Hereinafter, the achievement rate of the desulfurization reaction in the present invention means all values calculated by the formula 1.

[0054]

[Equation 1]

Further, the nitrogen content of the obtained heavy oil base material is not specified at all, but usually, the achievement rate of the denitrification reaction with respect to the feed oil is 10% or more, preferably 30% or more. Is.

The achievement rate of the denitrification reaction in the present invention means the value represented by the following equation 2. Hereinafter, the achievement rate of the denitrification reaction in the present invention means all values calculated by the equation 2.

[0057]

[Equation 2]

In the present invention, the overall achievement rate of the decomposition reaction by the two-stage hydrotreatment is arbitrary, but usually 20
% Or more, preferably 40% or more. The achievement rate of the decomposition reaction in the present invention means a value represented by the following formula 3. Hereinafter, the achievement rate of the decomposition reaction in the present invention means all values calculated by the equation 3.

[0059]

(Equation 3)

In the present invention, the desulfurization reaction achievement rate in the first-stage hydrotreatment is usually 70% of the desulfurization reaction achievement rate in the entire hydrotreatment including the second-stage hydrotreatment step. % Or more, preferably 80% or more, more preferably 9
It is desirable to occupy 0% or more.

In the present invention, the denitrification reaction achievement rate in the first-stage hydrotreatment is usually the denitrification reaction achievement rate in the entire hydrotreatment including the second-stage hydrotreatment step. Is preferably 50% or more, more preferably 80% or more, particularly preferably 90% or more.

Further, in the present invention, usually, the decomposition reaction achievement rate in the first stage hydrotreating step is smaller than the decomposition reaction achievement rate in the entire hydrotreating step including the second stage hydrotreating step. It is desirable to occupy preferably 75% or more, more preferably 85% or more, particularly preferably 90% or more.

The heavy oil base material obtained by the present invention can be used alone as a heavy oil product. Also, specifically, for example, petroleum distillation residue; kerosene; straight-run gas oil; vacuum gas oil; gas oil or residue obtained by pyrolyzing petroleum distillation residue and their hydrotreated oils; Other light oil base materials such as light oil (light cycle oil), heavy oil (heavy cycle oil), and slurry oil obtained from
Product heavy oil can also be used.

[0064]

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Example 1 A commercial desulfurization catalyst containing ₃ % by mass of NiO and 11% by mass of MoO _{3 on an} alumina carrier was used.
The catalyst was pre-sulphurized after being filled in the stainless steel reaction tower for the first stage hydrotreatment and the stainless steel reaction tower for the second stage hydrotreatment, which were arranged in series. Next, a vacuum distillation residue oil having the properties shown in Table 1 was used as a raw material oil, and a hydrogenation treatment was continuously performed using this reaction tower under the reaction conditions shown in Table 2. At this time, as shown in FIG. 1, the hydrotreating temperature of the first stage was gradually increased from the feedstock inlet to the feedstock outlet. Specifically, the upper part was 370 ° C., the middle part was 400 ° C., and the lower part was 430 ° C. First-stage and second-stage reaction conditions and properties of hydrotreated oil obtained from the first-stage and second-stage reaction tower outlets (toluene insoluble content, dry sludge content, sulfur content, nitrogen content Quantity, distillation 565
(° C fraction) is also shown in Table 2. Further, FIG. 2 shows the change over time in the pressure loss from the reactor outlet to the separator at this time.

(Example 2) Using the same feedstock and desulfurization catalyst as in Example 1, the maximum temperature of the first stage, that is, the temperature of the lower part of the first stage was changed to 420 ° C to carry out the hydrotreatment. . The second stage hydrotreatment temperature was the same as in Example 1. First-stage and second-stage reaction conditions and properties of hydrotreated oil obtained from the first-stage and second-stage reaction tower outlets (toluene insoluble content, dry sludge content, sulfur content, nitrogen content The amount and the distillation fraction (565 ° C. fraction) are also shown in Table 2. Further, FIG. 2 shows the change over time in the pressure loss from the reactor outlet to the separator at this time.

(Comparative Example 1) In order to clarify the effect of the low temperature treatment of the second stage reaction tower, the same feed oil and desulfurization catalyst as in Example 1 were used, and the second stage hydrotreating temperature was changed to the first stage. The hydrotreatment was carried out at a temperature equal to the maximum temperature of the step. The distribution of the hydrotreating temperature at this time is also shown in FIG. First-stage and second-stage reaction conditions and properties of hydrotreated oil obtained from the first-stage and second-stage reaction tower outlets (toluene insoluble content, dry sludge content, sulfur content, nitrogen content The amount and the distillation fraction (565 ° C. fraction) are also shown in Table 2. Further, FIG. 2 shows the change over time in the pressure loss from the reactor outlet to the separator at this time.

[0068]

[Table 1]

[0069]

[Table 2]

As is clear from the results shown in Table 2, according to the method of the present invention, even when the petroleum distillation residue having a relatively high sulfur content is used as the feedstock, the first stage of severe hydrotreatment is carried out. Depending on the conditions, the sulfur content is lower than that of the stock oil,
Moreover, it is possible to obtain a heavy oil base material having a low toluene insoluble content by the second-stage low-temperature hydrotreatment. Therefore, as shown in FIG. 2, it is possible to operate for a long period of time without increasing the pressure loss of the device. Further, the heavy oil base material obtained has a lower nitrogen content than the feed oil, and the distillation temperature is 565 ° C.
It can be seen that the contents of the above fractions are also greatly reduced.
On the other hand, in Comparative Example 1 in which the hydrotreatment temperature of the second stage was made equal to the maximum temperature of the first stage to perform the hydrotreatment,
Although the sulfur content and the nitrogen content were reduced to the same extent as in Example 1 and the fraction at the distillation temperature of 565 ° C. or higher was reduced, the hydrotreated oil obtained from the outlet of the reaction tower in the second stage was The toluene insoluble content is 550 mass ppm, which is very high as compared with the examples. For this reason, the pressure loss of the device rapidly increased, and the device had to be stopped early.

[0071]

According to the method of the present invention, even when a petroleum distillation residue with a relatively high sulfur content is used as a feedstock, the hydrotreatment is carried out in two stages under specific conditions. Finally, a heavy oil base material having a low sulfur content and a toluene insoluble content can be obtained. For this reason, it is possible to greatly relax the operating condition constraints that are usually received in hydrotreatment, such as the upper limit of the reaction temperature at which toluene insoluble matter does not precipitate and the lower limit of the reaction pressure. Can be greatly improved.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the hydrotreating temperature in the reaction tower and the position in the reaction tower.

FIG. 2 is a graph showing changes over time in pressure loss from the outlet of the reaction tower to the separator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichiro Fujiyama 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Nippon Oil & Oil Co., Ltd. Central Technology Research Institute

Claims (1)

[Claims] 1. A raw material oil having a dry sludge content of 0 to 5.0 mass% and a sulfur content of 1.0 to 10 mass%,
In the first stage filled with a hydrogenation catalyst, under the pressure, the maximum temperature in the catalyst bed is hydrotreated at 390 to 450 ° C.,
A hydrotreated oil having a sulfur content of 30% or less of the sulfur content of the feedstock and a toluene insoluble content of 10 mass ppm or more was obtained, and subsequently the hydrotreated oil of the first stage was filled with a hydrogenation catalyst. In the second stage, under pressurization, the maximum temperature in the catalyst bed is 10 ° C. or more lower than the maximum temperature in the first stage, and 4
A hydrotreated oil having a sulfur content of 30% or less of the sulfur content of the feedstock and a toluene insoluble content of 50% or less of the toluene insoluble content of the first stage is hydrotreated at 10 ° C or less. A method for producing a heavy oil base material, which comprises: