JP2000265177A - Hydrogenation treatment of heavy oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating stably for a long period a hydrogenation treatment system for petroleum-based heavy hydrocarbons containing metals and sulfur. SOLUTION: This hydrogenation treatment method comprises the 1st process where stock heavy oil comprising petroleum-based hydrocarbons containing both sulfur and metals is mainly hydrodemetallied using reaction column(s) and the 2nd process where the product thus obtained is mainly desulfurized using reaction column(s); wherein the aromaticity index ([the number of the aromatic carbon atoms in the asphaltene]/[the total number of the carbon atoms in the asphaltene]) of the asphaltene in the stock heavy oil is brought to >=0.50, and that of the asphaltene in the product oil from the 1st process to <=0.65.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hydrotreating heavy oil containing metal and sulfur.

[0002]

2. Description of the Related Art Heavy oil such as residual oil obtained by distillation of crude oil or the like usually contains sulfur and metals such as nickel and vanadium. In order to use such heavy oil as fuel oil or feedstock for cracking equipment,
It is necessary to remove these metal components and sulfur components, and they are usually used for each purpose after removing them by hydrogenation. However, in recent years, with the increase in the necessity of processing heavy crude oil, the amount of metal, sulfur, or residual carbon contained in heavy oil has been increasing, and is used in heavy oil hydrotreating processes. The load on the catalyst is increasing. On the other hand, from the viewpoint of protecting the environment, there is an increasing demand for reducing the sulfur content of fuel oil.

[0003] In such hydrogenation of heavy oil, blockage of catalyst pores due to deposition of metal or coke on the catalyst and reduction in activity due to coating of active sites are serious problems. For long-term stable operation of the equipment, it is indispensable to take measures against activity degradation. For this reason, various processes for long-term stable operation have been developed.For example, a multi-stage type in which a reaction tower mainly for demetallization is combined with a reaction tower mainly for hydrodesulfurization in front of the reaction tower. There is a heavy oil hydrotreating process.

[0004] In such a two-stage hydrotreating apparatus, the oil produced in the first step directly flows into the second step, so that the hydrogenation reaction efficiency in the demetallization reaction tower in the first step is reduced by the second step. It is an important factor that affects the performance and life of the process. For example, when a sufficient demetallization reaction does not proceed from the raw material oil in the first step reactor, a metal component slips to the desulfurization catalyst in the second step, and the catalytic activity deteriorates. In the case of deactivation by such a metal, the possibility of deactivation can be expected by controlling the metal concentration of the oil produced in the first step.

On the other hand, even when the hydrogenation reaction to a particularly heavy component in the feedstock in the first step reactor does not proceed sufficiently,
Since the coke precursor is generated and flows into the second step, the catalyst in the second step is deactivated by coke. However, although deactivation by coke is a serious problem to be solved as well as deactivation by metal in order to realize long-term operation of the apparatus, it has been a specific problem to anticipate such deactivation of the catalyst. Criteria were not provided.

[0006] As a technique for accelerating the addition of hydrogen to a hydrocarbon feedstock in a hydrotreating apparatus, a method of adding a hydrogen-donating solvent to a feedstock oil is known (for example, Japanese Unexamined Patent Publication No. Sho.
3-154795). However, this method is a technology that mainly suppresses the formation of carbonaceous matter or toluene-insoluble matter called dry sludge in the oil produced by the hydrotreating (hydrocracking) unit, and suppresses catalyst deactivation due to carbonaceous precipitation. It does not do.

On the other hand, the hydrogenation reaction may not proceed sufficiently in the first-step reaction tower because the flow state of gas-liquid or a mixed phase of gas-liquid and solid (hereinafter, mixed phase) in the reaction tower is not uniform. . In the case of the reaction tower type in which the catalyst particles are fixed, a flow state called a pulsating flow in which the flow of the liquid and the gas alternately occurs, or an uneven flow of the mixed phase due to channeling or bypass may occur. In order to prevent such a flow state and maintain an ideal irrigation flow, it is necessary to maintain appropriate liquid mass velocity and gas mass velocity, and also to pay attention to the physical properties of the liquid. On the other hand, in a reaction tower type in which catalyst particles flow and suspend, the gas phase is dispersed as bubbles in the reaction tower, but the gas-liquid contact area is reduced due to the fusion of bubbles, and pulsating flow or gas phase channeling is caused. In order to prevent the generation of gas bubbles and to maintain a uniform and finely dispersed bubble flow of the bubbles, it is necessary to similarly optimize the gas mass velocity and the physical properties of the liquid.

However, hydrogen gas supplies hydrogen necessary for desulfurization and demetallization reactions, has a role of removing reaction heat and improving the flow of feedstock oil, and furthermore, from the viewpoint of equipment design and economy. Therefore, it is difficult to change the flow rate of the hydrogen gas according to the flow state of the mixed phase. In addition, the raw material heavy oil is determined based on economics, production plan, and the like, and it is difficult to adjust its physical properties.

As described above, the known technique has many problems,
In a heavy oil hydrotreating unit consisting of a first step mainly for demetallation and a second step mainly for desulfurization, when processing heavy feedstock, the catalytic activity of the second step It was indispensable to adopt clear management measures to prevent the decline of the equipment and to enable long-term stable operation of the equipment.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a heavy oil comprising a first step mainly for demetallization and a second step mainly for desulfurization. In the hydrotreating equipment of the above, a clear guideline to suppress the deposition of carbonaceous material on the hydrotreating catalyst in the second step and to suppress the deterioration of the activity was given. An object of the present invention is to provide a method of operating stably for a long period of time.

[0011]

Means for Solving the Problems As a result of intensive studies, the present inventors have obtained the following findings and completed the present invention.
First, in order to prevent the activity of the hydrotreating catalyst in the second step from deteriorating, a parameter indicating the asphaltenic molecular structure called as aromatic index of asphaltene present in the oil produced in the first step is controlled to a certain value or less. It is clear that doing so is extremely important. Asphaltene is a heptane-insoluble and toluene-soluble heavy polymer component in heavy oil, as defined by the Japan Petroleum Institute method JPI-5S-22, and is widely associated with coke that precipitates on the catalyst. Are known.

In general, the ratio of the number of aromatic carbon atoms to the total number of carbon atoms in an asphaltene molecule is increased while the amount of asphaltenes in the asphaltene in the heavy oil is reduced by the hydrotreating process. This means that the aromaticity of asphaltene molecules has increased, and is due to the elimination reaction of alkyl groups and the dehydrogenation reaction of naphthene groups from asphaltene molecules composed of alkyl groups and polycyclic fused aromatics. is there. In particular, when sufficient hydrogenation of asphaltenes does not proceed, only the thermal history is received, so that the aromaticity of the asphaltenes is significantly increased.

The aromatic index indicates the degree of the aromaticity, and is expressed by [the number of aromatic carbon atoms in asphaltenes].
/ [Total number of carbon atoms in asphaltenes] and can be calculated by carbon-13 nuclear magnetic resonance spectroscopy ( ¹³ C-NMR). This measuring method is specified, for example, in ASTM (American Society for Testing and Materials) D-5292.

As a result of the experiment, when the asphaltenic aromatic index in the feed oil is 0.50 or more, the asphaltene having an increased aromatic index is liable to be changed to asphalten having a high aromatic index by demetallization treatment, and asphaltene having an increased aromatic index is likely to cause coke deposition on the catalyst. It turned out to be a connected carbonaceous precursor and flowed to the subsequent second step to promote carbonaceous deposition on the hydrotreating catalyst in the second step. In addition, it was clarified that such carbonaceous precipitation was particularly remarkable when the aromatic index of asphaltenes in the oil produced in the first step was 0.65 or more. Furthermore, when a raw oil obtained by adding a hydrogen-donating solvent or a low kinematic viscosity fraction to a raw heavy oil (hereinafter referred to as a mixed raw oil) was used, the asphaltenic aromatic index was 0.50 or more as described above. Even so, it was clarified that the aromatic index of asphaltenes in the hydrotreating product oil of the first step was suppressed from increasing, and that it greatly contributed to the prevention of activity deterioration of the hydrotreating catalyst of the second step.

[0015] That is, the present invention provides a first method using a hydrogenation treatment of heavy oil composed of petroleum hydrocarbons containing sulfur and metal to use one or more reaction towers for mainly removing metal. In the hydrotreating method having a step, and a second step using one or more reaction towers for mainly removing sulfur, the aromatic index of asphaltenes in the raw heavy oil is 0.50 or more, A method for hydrotreating heavy oil, wherein the aromatic index of asphaltene is 0.65 or less. Here, in the first step,
“Mainly remove metal (demetallize)” means that, in addition to the hydrodemetallization reaction, a hydrodesulfurization reaction has occurred to some extent, but the hydrodemetallization reaction is mainly performed, In the second step, “mainly removing sulfur (desulfurizing)” means that, in addition to the hydrodesulfurization reaction, a hydrodemetallation reaction has also occurred to some extent, but the hydrodesulfurization reaction is mainly performed. means.

Further, the present invention provides the above-mentioned hydrotreating method, wherein the reaction tower in the first step is any of a boiling bed, a gas-liquid upflow fixed bed, and a gas-liquid upflow moving bed. The reaction conditions are as follows: temperature 350-450 ° C, pressure 10-22MP
a, LHSV 0.1 to 1.0 h ^-1 , hydrogen / oil ratio 160 to 1000 Nm ³ /
m ³ , and the hydrogen gas purity used is 65% by volume or more,
This is a method for hydrotreating heavy oil.

Further, in the present invention, in the invention of the above-mentioned method for hydrotreating heavy oil, a hydrogen-donating solvent is added to the raw heavy oil in order to control the aromatic index of asphaltenes in the oil produced in the first step. Characterized by adding 1 to 30% by volume of
This is a method for hydrotreating heavy oil.

Further, the present invention provides the method for hydrotreating each heavy oil according to the present invention, wherein the raw heavy oil is added to the raw heavy oil at 50 ° C.
1 kinematic viscosity of 500 mm ² / s or less in a low dynamic viscosity fraction at 30
This is a method for hydrotreating heavy oil, characterized by adding volume%.

Further, according to the present invention, in the invention of the above-mentioned method for hydrotreating each heavy oil, the catalyst used in the first and second steps is obtained by supporting a Group 6 metal and a Group 9 to 10 metal on an alumina carrier. This is a method for hydrotreating heavy oil, which is a columnar catalyst or a spherical catalyst.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention and its operation will be described. In the present invention, hydrogenation of heavy oil composed of a first step by one or more reaction towers mainly for removing metal and a second step by one or more reaction towers for mainly removal of sulfur In the processing method,
The aromatic index of asphaltenes in the oil produced in the first step is controlled in order to prevent the deactivation of the catalyst in the second step by coke.

Specifically, the aromatic index of asphaltenes is
Asphaltene was extracted from the first step oil obtained by demetallizing a heavy oil of 0.50 or more, and the number of aromatic carbon atoms in asphaltenes / [total carbon atoms in asphaltenes] was determined by nuclear magnetic resonance spectroscopy. ] Is calculated. When the aromatic index exceeds 0.65, the carbonaceous deposition on the hydrotreating catalyst in the second step becomes remarkable, and the catalytic activity decreases remarkably. Therefore, the aromatic index is controlled to be 0.65 or less. I do. The lower the aromatic index, the greater the effect of preventing the catalyst from deteriorating in the second step.

In the present invention, the reaction column included in the first step is packed with a hydrodemetallation catalyst having a volume of a certain ratio or more to the reactor volume and mainly for the purpose of demetallization. I have. The demetallization reaction tower of this process has a fixed bed type of fixed-bed type reaction vessel in which the feedstock oil and hydrogen gas flow downwards in a gas-liquid down-flow co-current packed bed system (perfusate flow). In addition, a gas-liquid countercurrent packed bed method (gas rises and liquid descends) and a gas-liquid upward cocurrent packed bed method (both gas and liquid rise) are generally adopted. Further, a moving bed or an ebullated bed type reaction tower in which catalyst particles flow and suspend in a liquid phase, which can extract the deteriorated hydrotreating catalyst from the reaction tower during operation, may be employed. .

The reactor of the first step in the present invention is a multi-phase fixed bed or fluidized bed composed of a general gas-liquid-solid three-phase which is commercially operated as a hydrotreating process. A boiling bed, in which the gas is dispersed as bubbles,
Either a gas-liquid upflow fixed bed or a gas-liquid upflow moving bed. In these types of reactors, since the residence time of the feed oil is long, the severity of the reaction is high, and the flow state of the mixed phase is likely to be deteriorated due to the bubble flow. It works best on fixed or moving beds.

In the present invention, the reaction conditions of the hydrotreating apparatus can use the reaction conditions of the heavy oil hydrotreating process actually operated. The first step is preferably operated at a reaction temperature between 350 ° C and 450 ° C, more preferably between 360 and 430 ° C. The reaction temperature in the second step is preferably from 350 to 450 ° C, more preferably from 370 to 420 ° C. In addition, the first and second steps can be preferably operated at a hydrogen partial pressure of 10 to 22 MPa. The purity of the hydrogen gas used for the hydrogenation treatment is preferably at least 65% by volume, more preferably at least 80% by volume.

As the hydrogen-donating solvent to be added to the raw heavy oil for controlling the aromatic index of asphaltenes in the oil produced in the first step, any solvent having a hydrogen-donating property can be used. A hydrogen-donating solvent is a solvent containing a hydrocarbon capable of promoting a hydrogen transfer reaction to a molecule in a feed oil instead of hydrogen in a gaseous phase, and is a polycyclic aromatic hydrocarbon or a cycloaliphatic hydrocarbon. Has a high hydrogen-donating property.

Therefore, for example, various products from a hydrotreating unit in petroleum refining or cracked gas oil fractions from a catalytic cracking unit can be used. Further, it is also possible to distill the oil produced from the second step in the present hydrotreating apparatus, divide it into fractions, and recycle and use the fraction obtained by extracting a part. The hydrogen-donating solvent can be added in an amount of 1 to 30% by volume based on the feedstock oil so that the aromatic index of asphaltenes in the oil produced in the first step is 0.65 or less. If the addition amount is too small, the effect is small. If the addition amount is too large, there is a disadvantage in that the economical efficiency is reduced due to a decrease in the processing amount, the gas is generated due to the decomposition of light components, and the equipment is restricted due to a change in the product yield.

As the low kinematic viscosity fraction in the present invention, any petroleum hydrocarbon fraction can be used. For example, a straight distillate from a distillation apparatus, various products from a hydrotreating apparatus, or a cracked gas oil fraction from a catalytic cracking apparatus can be used. Moreover, after distilling the oil produced from the second step in the present hydrotreating apparatus and dividing it into fractions, a low kinematic viscosity fraction obtained by extracting a part can be recycled. The kinematic viscosity of the low kinematic viscosity fraction must be lower than that of the raw material heavy oil, and is preferably 500 mm ² / s (50 ° C.) or less, more preferably 100 mm ² / s or less (50 ° C.).

The boiling point of the low kinematic viscosity fraction is preferably
It is in the range of 180-450 ° C. As the low kinematic viscosity fraction, any component of a chain aliphatic hydrocarbon, a cycloaliphatic hydrocarbon and an aromatic hydrocarbon may be the main component, but a cycloaliphatic hydrocarbon or an aromatic hydrocarbon is included. Using a distillate has a better interaction with the raw material heavy oil, works synergistically with the effect as a hydrogen-donating solvent, has a large effect of improving the hydrogenation reaction efficiency to the raw material oil and asphaltene, and The effect of suppressing body formation is great. The low kinematic viscosity fraction has an aromatic index of asphaltene in the first step product oil.
It can be added in an amount of 1 to 30% by volume with respect to the feed oil so as to be 0.65 or less. If the amount is too small, the effect is small,
If the amount is too large, it is unsatisfactory because of reduced economical efficiency due to a decrease in the processing amount, gas generation due to light decomposition, and restriction on the apparatus due to a change in product yield.

The catalysts of the first and second steps used in the present invention both use alumina as a carrier and contain a Group 6 metal and a Group 9 to 10 metal used in a general heavy oil hydrotreating process. A porous columnar catalyst supported as an active metal,
Alternatively, a spherical catalyst can be used. Further, if necessary, a solid acid catalyst such as zeolite or a third component such as phosphorus or an alkali metal may be contained. The hydrotreating catalyst used in the first step has a hydrodemetallizing ability, and in order to capture metal-containing molecules in heavy oil having a large molecular size, the average pore diameter of the alumina carrier is preferably 8 nm to 50 nm, preferably. Is in the range of 10 nm to 30 nm. Further, the hydrotreating catalyst of the second step has hydrodesulfurization ability, the average pore diameter of the alumina carrier is in the range of 5 nm to 30 nm, preferably 5 nm to 20 nm, which is larger than the pores of the catalyst of the first step. Often small.

The amount of the active metal supported on the hydrotreating catalyst used in the present invention may be the amount used for a usual heavy oil desulfurization catalyst. That is, the weight of the carrier
Assuming 100% by weight, 1 to 10% by weight, preferably 3 to 6% by weight, of a Group 9 to 10 metal is contained in terms of element, and 3 to 30% by weight, preferably 6 to 15% by weight of Group 6 metal in terms of element. %contains. The amount of the metal, the amount of the Group 6 metal and the amount of the Group 9 to 10 metal to be supported, and the ratio thereof are optimal in view of the activity, deactivation rate, and economy.

The raw material heavy oil to which the present invention can be applied is a fraction having a boiling point of 350 ° C. or higher, such as an atmospheric residue or a vacuum residue obtained by distillation of crude oil. The amounts of sulfur and metals, kinematic viscosity and asphaltenes content in the feedstock are not particularly limited, but in the case of ordinary crude oil residue from residual pressure distillation equipment, sulfur content is 1 to 10% by weight and metal content is 10 to 10%. 1000 weight ppm
It is about. The kinematic viscosity at 50 ° C of the feedstock is 10
0 to 8000 mm ² / s. The method for asphaltene fractionation is defined in the Japan Petroleum Institute method JPI-5S-22. This method is a component obtained by heating a heavy oil sample with a specified amount of heptane at a heptane boiling point for a specified time, and then concentrating a toluene-soluble component among components unnecessary for heptane. The asphaltenes content in the feedstock is 1 to 10 as the residual oil of a normal crude pressure distillation unit.
% By weight.

The amount of sulfur in the produced oil can be arbitrarily determined as necessary, and the required desulfurization rate can be achieved by optimizing the reaction conditions such as the reaction temperature, pressure and liquid hourly space velocity.

In the present invention, the method of introducing the hydrogen-donating solvent or the low kinematic viscosity fraction is not particularly limited. For example, a method of mixing a raw heavy oil and a hydrogen-donating solvent or a low kinematic viscosity fraction, heating the mixture to a predetermined temperature with a heating furnace and injecting the mixture into a reaction tower, or individually raising the temperature to a predetermined temperature with a heating furnace. After that, a method in which the mixture is mixed before the reaction tower in the first step and then injected into the reaction tower can be adopted.

[0034]

EXAMPLES The embodiments of the present invention will be described in more detail with reference to Examples. [Example 1] As a first step, 1% by weight of nickel (in terms of Ni) and 3% by weight of molybdenum (in terms of Mo) were supported in a first reaction tube having an inner diameter of 1 inch with respect to 100% by weight of a γ-alumina carrier. 200 ml of the / 20 inch columnar catalyst was charged. As a second step, a γ-alumina carrier is placed in a second reaction tube having an inner diameter of 1 inch.
200 ml of a 1/20 inch column-shaped catalyst supporting 2% by weight of nickel (in terms of Ni) and 7% by weight of molybdenum (in terms of Mo) per 100% by weight was filled. Each of these catalysts was prepared by using a straight-run light oil (sulfur content: 3% by weight) containing dibutyl disulfide at 300 ° C., 14 MPa, and LHSV (for each catalyst capacity) = 0.
Preliminary sulfurization was performed for 24 hours under the conditions of 3h ^-1 and a hydrogen / oil ratio of 360 Nm ³ / m ³ .

These two reaction tubes were connected to each other to form a Middle Eastern atmospheric residue (sulfur content = 4.1% by weight, vanadium content = 60% by weight).
ppm, kinematic viscosity (50 ° C.) = 1733 mm ² / s, aromatic index of asphaltenes = 0.53) as the feed oil, and the reaction tube temperature (first,
380 ° C, pressure (both reaction tubes) = 14MP
a, LHSV (relative to total catalyst capacity) = 0.25 h ^-1 , hydrogen / oil ratio
Under the condition of (360 Nm ³ / m ³ ) (both reaction tubes), the first reaction tube was subjected to gas-liquid upward co-current flow, and the second reaction tube was subjected to gas-liquid downward co-current flow for hydrogenation treatment. After 1000 hours of oil passage, the sulfur content of the oil produced in the first step is 2.5% by weight, and the sulfur content of the oil produced from the second step is 0.95%.
% By weight. A distillate having a boiling point of 380 ° C to 440 ° C was collected from the resulting oil by distillation, and 10
% By weight to prepare a mixed raw material oil. Hydrogen gas having a hydrogen gas purity of 99% was used for the hydrogenation treatment.

The properties of the collected fractions are shown in Table 1, and the properties of the mixed raw material oil are shown in Table 2. Under the reaction conditions shown in Table 3, this mixed raw material oil was passed through the first reaction tube in a gas-liquid upward flow direction and the second reaction tube was passed in a gas-liquid downward flow direction to perform a hydrogenation treatment. Table 4 shows the sulfur content of the oil produced in the first and second steps 1000 hours after passing through the oil, the metal removal ratio in the first step, and the asphaltene aromatic index of the oil produced in the first step. Table 4 also shows the rate of decrease in the desulfurization rate in the second step between 1000 and 2000 hours of oil passage. The desulfurization rate in the second step is as follows: << ｛[Sulfur content in oil produced in the first step
(g)] − [Sulfur content in second step product (g)]｝ / [sulfur content in first step product oil (g)] × 100 (%).

[0037]

[Table 1]

[0038]

[Table 2] [Example 2] Boiling point generated by catalytic cracking device: 200 ° C to 35 ° C
A 10% by weight of the cracked gas oil fraction at 0 ° C. was mixed with the above-mentioned normal pressure residual oil to prepare a mixed raw material oil. Table 1 shows the properties of the cracked gas oil fraction.
Table 2 shows the properties of the mixed stock oil. Under the reaction conditions shown in Table 3, this mixed raw material oil was passed through the first reaction tube in a gas-liquid upward flow direction and the second reaction tube was passed in a gas-liquid downward flow direction to perform a hydrogenation treatment. Table 4 shows the sulfur content of the oil produced in the first and second steps 1000 hours after passing through the oil, the metal removal ratio in the first step, and the asphaltene aromatic index of the oil produced in the first step. Further 1000 to 2000
Table 4 also shows the rate of decrease in the desulfurization rate in the second step over time. In the hydrogenation treatment, hydrogen gas having the same purity as that used in Example 1 was used.

[0039]

[Table 3]

[0040]

[Table 4] Example 3 n-tetradecane was added to the above-mentioned normal pressure residue oil by adding 10
% By weight to prepare a mixed raw material oil. Table 1 shows the properties of n-tetradecane, and Table 2 shows the properties of the mixed stock oil.
Under the reaction conditions shown in Table 3, this mixed raw material oil was passed through the first reaction tube in a gas-liquid upward flow direction and the second reaction tube was passed in a gas-liquid downward flow direction to perform a hydrogenation treatment. Table 4 shows the sulfur content of the oil produced in the first and second steps 1000 hours after passing through the oil, the metal removal ratio in the first step, and the asphaltene aromatic index of the oil produced in the first step. Table 4 also shows the rate of decrease in the desulfurization rate in the second step between 1000 and 2000 hours of oil passage. In the hydrogenation treatment, hydrogen gas having the same purity as that used in Example 1 was used.

COMPARATIVE EXAMPLE 1 As in Example 1, hydrogenation of a Middle Eastern ordinary pressure residue was carried out. Table 4 shows the sulfur content of the oil produced in the first and second steps 1000 hours after passing through the oil, the metal removal ratio in the first step, and the asphaltene aromatic index of the oil produced in the first step. Table 4 also shows the rate of decrease in the desulfurization rate in the second step between 1000 and 2000 hours of oil passage. In the hydrogenation treatment, hydrogen gas having the same purity as that used in Example 1 was used.

[Comparative Example 2] As in Example 1, hydrogenation treatment was carried out on the residual oil under normal pressure. LHSV (for each catalyst volume) =
0.45h ^-1 . Table 4 shows the sulfur content of the oil produced in the first and second steps 1000 hours after passing through the oil, the metal removal ratio in the first step, and the asphaltene aromatic index of the oil produced in the first step. Table 4 also shows the rate of decrease in the desulfurization rate in the second step between 1000 and 2000 hours of oil passage. In the hydrogenation treatment, hydrogen gas having the same purity as that used in Example 1 was used.

Examples 1 to 3 confirm the effects of both the hydrogen donating solvent and the low kinematic viscosity fraction. Example 4 confirmed the effect of the low kinematic viscosity fraction. Regardless of which hydrogen donor solvent or low kinematic viscosity fraction is used, the aromatic index of asphaltenes in the oil produced in the first step is suppressed to 0.65 or less, and the decrease in the desulfurization activity of the catalyst in the second step is suppressed. be able to. Further, as a result of the efficient hydrogenation to the feedstock in the reaction tower in the first step, the desulfurization rate and the demetallation rate in the first step were improved and increased. Example 4
Indicates that the low kinematic viscosity fraction to be added is effective even with a chain aliphatic hydrocarbon, but the fraction containing an aromatic hydrocarbon or a cycloaliphatic hydrocarbon is more effective. .

As is evident from the above results, the present invention is effective in suppressing an increase in the aromatic index of asphaltenes in the oil produced in the first step and suppressing the transformation into carbonaceous precursors.
This makes it possible to prevent the deterioration of the hydrotreating catalyst in the second step.

[0045]

According to the present invention, a carbonaceous precursor from the first step to the second step is obtained by employing the present invention in a heavy oil hydrotreating apparatus including a reaction tower mainly for demetallization in the first step. Of inflow of hydrogen and enable stable long-term operation of the hydrotreating unit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuaki Hayasaka 1-17-1-330 Kodai, Miyamae-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor Shigeto Hatanaka 832-1 Imajukucho, Asahi-ku, Yokohama-shi, Kanagawa Prefecture -Hill Imajuku 26-102 F term (reference) 4H029 CA00 DA00 DA09 DA14

Claims (5)

[Claims] 1. A first step of mainly hydrodemetallizing a raw material heavy oil comprising a petroleum hydrocarbon containing a sulfur component and a metal component by using one or a plurality of reaction towers, and one or more reaction towers In the hydrotreating method having the second step of mainly desulfurizing using asphaltene, the aromatic index of asphaltenes in the raw heavy oil ([number of aromatic carbon atoms in asphaltenes] / [total number of carbon atoms in asphaltenes]) Is 0.50 or more, and the aromatic index of asphaltene in the first step product oil is 0.65 or less. 2. The reaction column of the first step is any one of a boiling bed, a fixed bed of gas-liquid upward flow type and a moving bed of gas-liquid upward flow type, and the reaction conditions are a temperature of 350 to 450 ° C. and a pressure of 350 ° C. 10-22MP
a, LHSV 0.1 to 1.0 h ^-1 , hydrogen / oil ratio 160 to 1000 Nm ³ /
m ³ , and the hydrogen gas purity used is 65% by volume or more,
The method for hydrotreating heavy oil according to claim 1. 3. The method according to claim 1, wherein a hydrogen-donating solvent is added to the raw heavy oil in an amount of 1 to 30% by volume in order to control the aromatic index of asphaltenes in the oil produced in the first step.
3. The method for hydrotreating heavy oil according to any one of claims 1 to 2. 4. The kinematic viscosity at 50 ° C. is 500 m in order to control the aromatic index of asphaltenes in the first step product oil.
The heavy oil hydrotreating method according to claim 1, wherein a low kinematic viscosity fraction of m ² / s or less is added to the raw heavy oil in an amount of 1 to 30% by volume. 5. The catalyst used in the first and second steps,
The method for hydrotreating heavy oil according to any one of claims 1 to 4, wherein the catalyst is a columnar catalyst or a spherical catalyst having a Group 6 and Group 9 to 10 metal supported on an alumina carrier.