JP7760490B2 - Vacuum gas oil hydrotreating catalyst, method for producing vacuum gas oil hydrotreating catalyst, and method for hydrotreating vacuum gas oil - Google Patents

Description

The present invention relates to a vacuum gas oil hydrotreating catalyst, a method for producing a vacuum gas oil hydrotreating catalyst, and a method for hydrotreating vacuum gas oil .
This application claims priority based on Japanese Patent Application No. 2020-056301, filed on March 26, 2020, the contents of which are incorporated herein by reference.

The oil fractions obtained by distillation and cracking of crude oil generally contain sulfur compounds, and when these oils are used as fuel, sulfur oxides and other substances are generated due to these sulfur compounds. For this reason, the process of producing petroleum products from crude oil includes a hydrotreating step to remove the sulfur compounds.

Vacuum gas oil, a distillate obtained by further vacuum distilling the atmospheric residue obtained by processing crude oil in an atmospheric distillation unit, also contains high concentrations of sulfur compounds. For this reason, vacuum gas oil is hydrotreated in an indirect desulfurization unit.

Hydrotreating catalysts are being developed to improve the efficiency of hydrotreating using indirect desulfurization units. Hydrotreating catalysts that have been developed use Group 6 metals and cobalt as active species, with these active species supported on an inorganic oxide support primarily composed of alumina.

Patent Document 1 discloses a vacuum gas oil hydrotreating catalyst containing molybdenum, cobalt, and phosphorus. It discloses that when the state of the alumina constituting the carrier in the hydrotreating catalyst is analyzed using ^27Al -NMR, the proportion of the area intensity attributable to tetrahedral Al in the coordination structure of Al atoms is 30% or more of the total, and the external surface area of the catalyst is 3500 mm ² /ml or more, thereby improving the hydrotreating activity.

Japanese Patent Application Laid-Open No. 2004-74075

In recent years, there has been an increasing demand for bottomless processes, and heavy hydrocarbon oils are hydrotreated and then processed in a fluid catalytic cracker to produce gasoline and middle distillates such as kerosene and diesel. The sulfur content of the feedstock oil supplied to the fluid catalytic cracker must be reduced to a certain level or below in order to protect the fluid catalytic cracking catalyst, so heavy hydrocarbon oils that are difficult to desulfurize must be hydrotreated. Therefore, there is a need for a hydrotreating catalyst that has high hydrotreating activity for heavy hydrocarbon oils and is resistant to activity degradation. However, the hydrotreating activity and catalyst life of the hydrotreating catalyst described in Patent Document 1 are insufficient.

The present invention has been made in consideration of the above circumstances, and aims to provide a heavy hydrocarbon oil hydrotreating catalyst that has high hydrotreating activity for heavy hydrocarbon oil and is resistant to activity degradation, a method for producing the heavy hydrocarbon oil hydrotreating catalyst, and a heavy hydrocarbon oil hydrotreating method using the heavy hydrocarbon oil hydrotreating catalyst.

As a result of extensive research to achieve the above-mentioned objective, the inventors discovered that by using a phosphorus- and zinc-containing alumina carrier containing specific amounts of phosphorus and zinc as a carrier and using a heavy hydrocarbon oil hydrotreating catalyst in which at least one metal selected from Group 6 metals of the periodic table and cobalt are supported in specific amounts on the phosphorus- and zinc-containing alumina carrier, the hydrotreating activity of heavy hydrocarbon oil is high and the activity is less likely to decrease, and thus completed the present invention.

That is, the present invention relates to the following heavy hydrocarbon oil hydrotreating catalyst, method for producing heavy hydrocarbon oil hydrotreating catalyst, and method for hydrotreating heavy hydrocarbon oil.
[1] A phosphorus- and zinc-containing alumina carrier containing 0.1 to 4 mass% of phosphorus in oxide equivalents based on the carrier and 1 to 8 mass% of zinc in oxide equivalents based on the carrier;
The catalyst for hydrotreating heavy hydrocarbon oils comprises a carrier on which at least one metal selected from Group 6 metals of the periodic table is supported in an amount of 8 to 30 mass % in terms of oxide, based on the catalyst, and cobalt in an amount of 2 to 8 mass % in terms of oxide, based on the catalyst.
[2] A method for producing a catalyst for hydrotreating heavy hydrocarbon oil, comprising a step of supporting at least one metal selected from Group 6 of the periodic table on a phosphorus- and zinc-containing alumina support, the alumina support containing phosphorus in an amount of 0.1 to 4 mass % in terms of oxide, based on the support, and zinc in an amount of 1 to 8 mass % in terms of oxide, based on the support, in such a manner that the metal contains 8 to 30 mass % in terms of oxide, based on the catalyst, and cobalt in an amount of 2 to 8 mass % in terms of oxide, based on the catalyst.
[3] A method for producing hydrotreated heavy hydrocarbon oil, comprising contacting heavy hydrocarbon oil with the hydrotreating catalyst for heavy hydrocarbon oil according to [1] at a hydrogen/oil ratio of 100 to 1000 Nm ³ /kL, a hydrogen partial pressure of 3.5 to 10 MPa, a temperature of 330 to 430°C, and a liquid hourly space velocity of 0.2 ^to 2 hr -1.
[4] A method for hydrotreating heavy hydrocarbon oils, comprising contacting heavy hydrocarbon oils with the hydrotreating catalyst for heavy hydrocarbon oils according to [1] at a hydrogen/oil ratio of 100 to 1000 Nm ³ /kL, a hydrogen partial pressure of 3.5 to 10 MPa, a temperature of 330 to 430°C, and a liquid hourly space velocity of 0.2 to ² hr -1.

The present invention provides a heavy hydrocarbon oil hydrotreating catalyst that has high hydrotreating activity for heavy hydrocarbon oil and is resistant to activity degradation. It also provides a method for producing the heavy hydrocarbon oil hydrotreating catalyst and a heavy hydrocarbon oil hydrotreating method using the heavy hydrocarbon oil hydrotreating catalyst.

The following describes in detail the embodiments of the present invention. However, the following description is an example of an embodiment of the present invention, and the present invention is not limited to these contents and can be modified and implemented within the scope of its essence.

<Heavy hydrocarbon oil hydrotreating catalyst>
The heavy hydrocarbon oil hydrotreating catalyst of this embodiment (hereinafter may be simply referred to as "hydrotreating catalyst") uses a phosphorus- and zinc-containing alumina as a support, the support containing phosphorus in an amount of 0.1 to 4 mass % in oxide equivalent, based on the support, and zinc in an amount of 1 to 8 mass % in oxide equivalent, based on the support, and supports at least one metal selected from Group 6 of the periodic table in an amount of 8 to 30 mass % in oxide equivalent, based on the catalyst, and cobalt in an amount of 2 to 8 mass % in oxide equivalent, based on the catalyst, on the support.
In this specification, the term "Group 6 metal of the periodic table" (hereinafter sometimes referred to as "Group 6 metal") means a Group 6 metal in the long-form periodic table.
In this specification, the Group 6 metals and cobalt are collectively referred to as "hydrogenation active components."

A phosphorus-zinc-containing alumina carrier containing phosphorus and zinc will be described.
The main component of the support of the hydrotreating catalyst of this embodiment is alumina. Various types of alumina can be used, such as α-alumina, β-alumina, γ-alumina, and δ-alumina. Alumina that is porous and has a high specific surface area is preferred, and γ-alumina is more preferred.
The purity of the alumina is preferably 98% by mass or more, and more preferably 99% by mass or more.
Impurities in alumina include SO ₄ ²⁻ , Cl ⁻ , Fe ₂ O ₃ , Na ₂ O, etc. It is preferable that the content of these impurities is as low as possible. The total content of impurities relative to the total mass of alumina is preferably 2 mass% or less, and more preferably 1 mass% or less.
As for each component, it is preferable that SO ₄ ^2- is 1.5 mass % or less, and Cl ^- , Fe ₂ O ₃ , and Na ₂ O are each 0.1 mass % or less, relative to the total mass of alumina.

The alumina used as the support for the hydrotreating catalyst of this embodiment may be a composite alumina obtained by compounding at least one oxide selected from zeolite, boria, silica, and zirconia. The composite alumina refers to a mixture or composite oxide of alumina and at least one oxide selected from zeolite, boria, silica, and zirconia.
The content of alumina relative to the total mass of the composite alumina is preferably 92 to 99.9 mass%, more preferably 95 to 98 mass%. The content of at least one oxide selected from zeolite, boria, silica, and zirconia relative to the total mass of the composite alumina is preferably 0.1 to 8 mass%, more preferably 2 to 5 mass%. As the zeolite, boria, silica, and zirconia composite components, those generally used as support components for this type of catalyst can be used.

The support of the hydrotreating catalyst of this embodiment is a phosphorus- and zinc-containing alumina support obtained by further incorporating phosphorus and zinc into an alumina support (including a composite alumina support).
Phosphorus and zinc are added as components for improving the quality of active sites in order to improve the hydrotreating activity and residual carbon removal activity per amount of hydrotreating active component. Phosphorus and zinc play a role in precisely creating a highly active hydrotreating active component-sulfur phase, such as a CoMoS phase or a CoWS phase. Furthermore, the inclusion of phosphorus and zinc suppresses the decrease in activity of the hydrotreating catalyst.

The zinc content in the support of the hydrotreating catalyst of this embodiment is 1 to 8 mass% in oxide equivalent, based on the support, preferably 1 to 6 mass%, more preferably 1 to 5 mass%, and even more preferably 1 mass% or more but less than 4 mass%. When the zinc content is at or above the lower limit of the above range, the sulfidity of the Group 6 metal can be sufficiently improved. In addition, a decrease in the activity of the hydrotreating catalyst is suppressed. When the zinc content is at or below the upper limit of the above range, a decrease in pore volume and specific surface area is unlikely to occur, the Group 6 metal is sufficiently dispersed, and the sulfidity of cobalt is unlikely to decrease.

The phosphorus content in the support of the hydrotreating catalyst of this embodiment is 0.1 to 4 mass% (oxide equivalent) based on the support, and preferably 0.5 to 2 mass%. When the phosphorus content is at or above the lower limit of the range, the sulfidity of the Group 6 metal can be sufficiently improved. In addition, a decrease in the activity of the hydrotreating catalyst is suppressed. When the phosphorus content is at or below the upper limit of the range, a decrease in pore volume and specific surface area is unlikely to occur, and the Group 6 metal is sufficiently dispersed, allowing the full effect of adding phosphorus to be obtained.

In this specification, with regard to the phosphorus and zinc contents, "based on the carrier, in oxide equivalent" means the ratio of the mass of phosphorus oxide and the mass of zinc oxide to the total mass of all elements contained in the carrier calculated as their respective oxides. The mass of phosphorus oxide is calculated in terms of _diphosphorus pentoxide ( _P2O5 ), and the mass of zinc oxide is calculated in terms of zinc oxide (ZnO).
In this specification, the mass of an element contained in a support or a hydrotreating catalyst can be measured by inductively coupled plasma atomic emission spectrometry.

The hydrotreating catalyst of this embodiment contains phosphorus and zinc, which is thought to mitigate the interaction between the Group 6 metal or cobalt and the support, facilitating the sulfurization of the Group 6 metal and cobalt, respectively. On the other hand, if the interaction between the Group 6 metal or cobalt and the support becomes too weak, aggregation of the hydrogenation active components occurs, so precise control is required for the addition of phosphorus and zinc. In the hydrotreating catalyst of this embodiment, the precisely controlled addition of phosphorus and zinc is thought to maintain a high dispersion of the hydrogenation active component-sulfur phase, such as the CoMoS phase or CoWS phase, while also optimizing the structural morphology, such as the number of layers.

The phosphorus- and zinc-containing alumina support of the hydrotreating catalyst of this embodiment preferably has the following physical properties:

The specific surface area of the phosphorus- and zinc-containing alumina support, as measured by the nitrogen adsorption method (BET method), is preferably 200 to 400 m ² /g, more preferably 250 to 360 m ² /g. When the specific surface area is at least the lower limit of the above range, the hydrogenation active component is sufficiently dispersed, resulting in high hydrotreating activity. When the specific surface area is at most the upper limit of the above range, the support has a sufficiently large pore diameter, resulting in a sufficiently large pore diameter for the hydrotreating catalyst. As a result, sulfur compounds are sufficiently diffused into the catalyst pores, resulting in high hydrotreating activity. In other words, when the specific surface area is within the above range, the hydrotreating active component is well dispersed, and a hydrotreating catalyst having a sufficiently large pore diameter can be obtained.

The average pore diameter of the phosphorus- and zinc-containing alumina support in the pore distribution measured by mercury intrusion porosimetry is preferably 4 to 12 nm, more preferably 6 to 8 nm. When the average pore diameter is within this range, the support has a sufficient internal pore surface area, and sulfur compounds diffuse sufficiently into the catalyst pores, resulting in high hydrotreating activity.

The pore volume of the phosphorus- and zinc-containing alumina support, as measured by mercury intrusion porosimetry, is preferably 0.5 to 0.9 mL/g, more preferably 0.55 to 0.8 mL/g. When the pore volume is equal to or greater than the lower limit of the above range, a sufficient amount of solvent can penetrate into the pores when preparing the catalyst using a conventional impregnation method. A sufficient amount of solvent allows the hydrogenation active component to dissolve well in the solvent, improving the dispersibility of the hydrogenation active component and resulting in a highly active catalyst. One method for increasing the solubility of the hydrogenation active component is to add a large amount of acid, such as nitric acid, but adding too much reduces the surface area of the support, which is the main cause of reduced hydrotreating activity. When the pore volume is equal to or less than the upper limit of the above range, the specific surface area is sufficiently large, improving the dispersibility of the hydrogenation active component. In other words, when the pore volume is within the above range, the catalyst has a sufficient specific surface area and can accommodate a sufficient amount of solvent within the pore volume, resulting in both good solubility and dispersibility of the hydrogenation active component and further improving hydrotreating activity.

The hydrotreating catalyst of this embodiment is a catalyst in which a Group 6 metal and cobalt are supported as hydrogenation active components on the phosphorus- and zinc-containing alumina support.

The zinc content in the hydrotreating catalyst of this embodiment is preferably 0.5 to 7 mass%, more preferably 0.7 to 6.5 mass%, and even more preferably 1 to 6 mass%, calculated as oxide based on the catalyst. When the zinc content is at or above the lower limit of the above range, the sulfidity of the Group 6 metal can be sufficiently improved. Furthermore, a decrease in the activity of the hydrotreating catalyst is suppressed. When the zinc content is at or below the upper limit of the above range, a decrease in pore volume and specific surface area is unlikely to occur, the Group 6 metal is sufficiently dispersed, and the sulfidity of cobalt is unlikely to decrease.

The phosphorus content in the hydrotreating catalyst of this embodiment is preferably 0.5 to 8 mass% (oxide equivalent) based on the catalyst, more preferably 0.5 to 4.5 mass%, and even more preferably greater than 3.6 mass% and 4.5 mass% or less. When the phosphorus content is at or above the lower limit of the above range, the sulfidity of the Group 6 metal can be sufficiently improved. In addition, a decrease in the activity of the hydrotreating catalyst is suppressed. When the phosphorus content is at or below the upper limit of the above range, a decrease in pore volume and specific surface area is unlikely to occur, and the Group 6 metal is sufficiently dispersed, allowing the effects of adding phosphorus to be fully achieved.

In this specification, with regard to the phosphorus and zinc contents, "catalyst-based, oxide equivalent" means the ratio of the mass of phosphorus oxide and the mass of zinc oxide to the total mass of all elements contained in the catalyst calculated as their respective oxides. The mass of phosphorus oxide is calculated in terms of diphosphorus pentoxide (P ₂ O ₅ ), and the mass of zinc oxide is calculated in terms of zinc oxide (ZnO).

Examples of Group 6 metals include molybdenum (Mo), tungsten (W), and chromium (Cr). Among these, molybdenum is preferred because of its high hydrotreating activity per unit mass.
The Group 6 metal to be supported may be one type only, or two or more types may be used in combination.
The amount of Group 6 metal supported on the phosphorus- and zinc-containing alumina support is 8 to 30 mass %, preferably 10 to 25 mass %, calculated as oxide based on the catalyst. When the amount of Group 6 metal supported is equal to or greater than the lower limit of the above range, it is sufficient to realize the effects attributable to the Group 6 metal. When the amount of Group 6 metal supported is equal to or less than the upper limit of the above range, the Group 6 metal is less likely to aggregate and is sufficiently dispersed. In other words, the amount of Group 6 metal supported does not exceed the amount that can be efficiently dispersed, and the catalyst surface area does not decrease significantly, thereby improving catalytic activity.

The amount of cobalt supported on the phosphorus- and zinc-containing alumina support is 2 to 8 mass % of the catalyst, calculated as oxide, with 2.5 to 5 mass % being preferred. When the amount of cobalt supported is equal to or greater than the lower limit of the range, sufficient active sites attributable to cobalt are obtained. When the amount of cobalt supported is equal to or less than the upper limit of the range, the cobalt is less likely to aggregate and is sufficiently dispersed.

Hydrotreatment reactions include desulfurization reactions and hydrogenation reactions other than desulfurization reactions. When hydrotreatment reactions are performed in a reactor with a low hydrogen partial pressure with the primary purpose of desulfurization reactions, the progress of hydrogenation reactions other than desulfurization reactions consumes hydrogen in the reactor, making coking more likely to occur. By including cobalt in the hydrotreatment catalyst of this embodiment, hydrogenation reactions other than desulfurization reactions can be suppressed, thereby suppressing the occurrence of coking. As a result, the activity of the hydrotreatment catalyst is suppressed from decreasing over time.

Here, with regard to the amounts of the Group 6 metals and cobalt supported, "on a catalyst basis, in oxide equivalent" means the ratio of the mass of each metal oxide to the total mass of all elements contained in the catalyst calculated as their respective oxides. The masses of the Group 6 metals and cobalt oxides are calculated by converting the Group 6 metals into hexavalent oxides (e.g., _MoO3 for Mo) and the cobalt into divalent oxides (CoO).

In the amounts of the Group 6 metal and cobalt components supported, the optimum mass ratio of the Group 6 metal, which is a hydrogenation active component, to cobalt is preferably 0.14 to 0.3, expressed as [mass of cobalt oxide]/[mass of cobalt oxide+mass of Group 6 metal oxide].
When the ratio of the mass of cobalt oxide to the total mass of the Group 6 metal oxide and cobalt oxide is equal to or greater than the lower limit of the above range, a hydrogenation active component-sulfur phase such as a CoMoS phase or a CoWS phase, which is considered to be an active site for the hydrotreating reaction, is sufficiently formed, thereby increasing hydrotreating activity.When the ratio of the mass of cobalt oxide to the total mass of the Group 6 metal oxide and cobalt oxide is equal to or less than the upper limit of the above range, metal species not involved in hydrotreating activity (CoS species and Co spinel species incorporated into the lattice of the support) are less likely to be formed, thereby increasing hydrotreating activity.

The hydrotreating catalyst may contain impurities such as SO ₄ ^2- , Cl ^- , Fe ₂ O ₃ , and Na ₂ O derived from the alumina contained in the carrier. It is preferable that the amount of these impurities is as small as possible, and the total content of impurities relative to the total mass of the hydrotreating catalyst is preferably 2 mass% or less, and more preferably 1 mass% or less. For each component, it is preferable that SO ₄ ^2- is 1.5 mass% or less, and that Cl ^- , Fe ₂ O ₃ , and Na ₂ O are each 0.1 mass% or less.

The hydrotreating catalyst of this embodiment preferably has the following physical properties in order to enhance hydrotreating activity for heavy hydrocarbon oils.

The specific surface area of the hydrotreating catalyst of this embodiment, as measured by the BET method, is preferably 150 to 300 m ² /g, more preferably 190 to 250 m ² /g. When the specific surface area is at least the lower limit of the above range, the hydrotreating active component is sufficiently dispersed, resulting in high hydrotreating activity. When the specific surface area is at most the upper limit of the above range, the hydrotreating catalyst has a sufficiently large pore diameter.
Therefore, the sulfur compounds are sufficiently diffused into the catalyst pores, resulting in high hydrotreating activity. That is, when the specific surface area is within the above range, it is possible to improve both the dispersibility of the hydrotreating active component and the diffusibility of the sulfur compounds into the catalyst pores during hydrotreating.

The average pore diameter in the pore distribution of the hydrotreating catalyst of this embodiment, as measured by mercury intrusion porosimetry, is preferably 5 to 20 nm, and more preferably 7 to 11 nm. When the average pore diameter is within this range, the catalyst has a sufficient internal pore surface area (i.e., the effective surface area of the catalyst) while increasing the diffusibility of sulfur compounds into the catalyst pores, thereby further improving hydrotreating activity.

The pore volume of the hydrotreating catalyst of this embodiment, as measured by mercury intrusion porosimetry, is preferably 0.45 to 0.8 mL/g, more preferably 0.45 to 0.7 mL/g. When the pore volume is equal to or greater than the lower limit of the above range, sulfur compounds diffuse sufficiently within the catalyst pores during hydrotreating, improving hydrotreating activity. When the pore volume is equal to or less than the upper limit of the above range, the specific surface area of the catalyst can be prevented from becoming extremely small. When the pore volume is within the above range, both the dispersibility of the hydrotreating active components and the diffusibility of sulfur compounds into the catalyst pores during hydrotreating can be improved.

In order to increase the effective number of pores that satisfy the above-mentioned average pore diameter and pore volume, the pore size distribution of the hydrotreating catalyst of this embodiment is such that the ratio of the volume of pores having pore diameters within ±1.5 nm of the average pore diameter to the total pore volume is preferably 65% or more, and more preferably 70% or more.

Furthermore, the distribution state of the hydrogenation active components in the hydrotreating catalyst of this embodiment is preferably a uniform type in which the hydrogenation active components are uniformly distributed in the catalyst.

<Method for producing a catalyst for hydrotreating heavy hydrocarbon oil>
The method for producing a heavy hydrocarbon oil hydrotreating catalyst of this embodiment includes a step of supporting at least one metal selected from Group 6 of the periodic table on a phosphorus- and zinc-containing alumina support containing 0.1 to 4 mass % of phosphorus, calculated as oxide, based on the support, and 1 to 8 mass % of zinc, calculated as oxide, based on the support, in an amount of 8 to 30 mass % of metal selected from Group 6 of the periodic table, calculated as oxide, based on the catalyst, and 2 to 8 mass % of cobalt, calculated as oxide, based on the catalyst.

The phosphorus- and zinc-containing alumina carrier can be prepared, for example, by preparing an alumina gel; adding a phosphorus compound and a zinc compound to the alumina gel and kneading them so that the alumina gel contains 0.1 to 4 mass % of phosphorus, calculated as oxide, based on the carrier, and 1 to 8 mass % of zinc, calculated as oxide, based on the carrier; molding the resulting mixture; and drying and firing the resulting molded product.

To obtain the phosphorus- and zinc-containing alumina support used in the hydrotreating catalyst of this embodiment, first, an alumina gel is obtained by a conventional method.
Any alumina raw material can be used as long as it contains aluminum, but aluminum salts such as aluminum sulfate, aluminum nitrate, etc. These alumina raw materials are usually provided as an aqueous solution, and although there are no particular limitations on the concentration, it is preferably 2 to 50 mass %, more preferably 5 to 40 mass %, based on the total mass of the aqueous solution.

To prepare alumina gel, for example, first prepare a slurry by mixing an aqueous solution of sulfuric acid, sodium aluminate, and aluminum hydroxide in a stirring vessel. The resulting slurry is then dehydrated using a rotating cylindrical continuous vacuum filter and washed with pure water to obtain alumina gel.

The resulting alumina gel is then washed until SO ₄ ^2- and Na ⁺ are no longer detectable in the filtrate, and the alumina gel is then mixed with pure water to form a homogeneous slurry. The resulting alumina gel slurry is dehydrated until the water content relative to the total mass of the slurry is 60 to 90 mass %, to obtain a cake.

In the manufacturing method of this embodiment, it is preferable to dehydrate the alumina gel slurry using a filter press. A filter press is a device that filters a slurry by applying compressed air or pump pressure, and is generally called a filter press. Filter presses are available in plate and frame types and concave plate types. In a plate and frame type filter press, filter plates and filter frames are alternately clamped between end plates, and the slurry is filtered by being forced into the filter frames. The filter plates have grooves that serve as filtrate flow paths, and filter cloth is stretched over the filter frames. On the other hand, in a concave plate type filter press, filter cloth and concave plate type filter plates are alternately arranged and clamped between the end plates to form a filter chamber (Reference: Chemical Engineering Handbook, p. 715).

In this way, in the manufacturing method of this embodiment, the moisture content is adjusted using the above-mentioned filter press when preparing the alumina used for the carrier. Dehydration using the filter press can improve the surface condition of the alumina carrier and the sulfidity of the hydrogenation active component. The dehydration process using the filter press is preferably performed after at least one of the above-mentioned alumina gel preparation process and the process of kneading the phosphorus compound and zinc compound described below, or may be performed after both processes. It is particularly preferable to perform the dehydration process after preparing the alumina gel and before kneading the phosphorus compound and zinc compound.

In addition to the above-described method, other methods for preparing alumina gel include a method of neutralizing an aqueous solution containing an alumina raw material with a neutralizing agent such as sodium aluminate, aluminic acid, or ammonia, and a method of mixing the aqueous solution with a precipitating agent such as hexanemethylenetetramine or calcium carbonate.
The amount of the neutralizing agent used is not particularly limited, but is preferably 30 to 70 mass % based on the total amount of the aqueous solution containing the alumina raw material and the neutralizing agent.The amount of the precipitating agent used is not particularly limited, but is preferably 30 to 70 mass % based on the total amount of the aqueous solution containing the alumina raw material and the precipitating agent.

When composite alumina is prepared by combining an oxide such as zeolite with the above-mentioned zeolite as a support for a hydrotreating catalyst, alumina gel is first prepared by a conventional method, and the resulting alumina gel is then aged, washed, dehydrated, dried, and moisture-adjusted before adding the phosphorus compound and zinc. Alumina can be composited with an oxide such as zeolite by coprecipitation, kneading, or other methods. The composite alumina gel is then aged, washed, dehydrated, dried, and moisture-adjusted. It is also preferable to use a press filter for the final dehydration step before molding the composite alumina gel.

Various zinc compounds can be used as the zinc compound to be added to the support of the hydrotreating catalyst of this embodiment, including zinc oxide, zinc nitrate, zinc sulfate, zinc carbonate, zinc chloride, zinc acetate, zinc hydroxide, and zinc oxalate. Of these, zinc oxide, zinc nitrate, and zinc sulfate are preferred, with zinc oxide being particularly preferred.

Various compounds can be used as the phosphorus compound added to the support of the hydrotreating catalyst of this embodiment. Examples of phosphorus compounds include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, with orthophosphoric acid being preferred.

A phosphorus compound and a zinc compound are added to the alumina gel obtained above by kneading. Specifically, a phosphorus compound and a zinc compound heated to 15-90°C are added to a water-adjusted alumina gel heated to 50-90°C. The mixture is then kneaded and stirred using a heated kneader or the like to obtain a kneaded mixture of alumina gel, phosphorus compound, and zinc compound. As mentioned above, dehydration using a press filter may be performed after kneading and stirring the alumina gel, phosphorus compound, and zinc compound. The phosphorus compound may be added directly, or a phosphorus solution (or suspension) in which the phosphorus compound is dissolved (or suspended) in a solvent may be added.

The resulting kneaded product is then molded, dried, and calcined to obtain a phosphorus- and zinc-containing alumina carrier. The molding of the kneaded product can be carried out using various molding methods, such as extrusion molding and pressure molding. The drying temperature for drying the resulting molded product is preferably 15 to 150°C, more preferably 80 to 120°C. The drying time is preferably 30 minutes or longer. The calcination temperature can be set as needed; for example, to obtain γ-alumina, the calcination temperature is preferably 450°C or higher, more preferably 480 to 600°C. The calcination time is preferably 2 hours or longer, more preferably 3 to 12 hours.

The zinc compound and phosphorus compound may be added to the alumina support by methods other than kneading. Methods for supporting zinc compounds and phosphorus compounds on the alumina support by methods other than kneading include known methods such as impregnation, coprecipitation, deposition, and ion exchange. Examples of impregnation methods include evaporation to dryness, in which the alumina support is immersed in an impregnation solution in excess of the total pore volume of the alumina support and then the solvent is completely dried to support the components; equilibrium adsorption, in which the alumina support is immersed in an impregnation solution in excess of the total pore volume of the alumina support and then subjected to solid-liquid separation such as filtration to obtain a catalyst with the components supported; and pore filling, in which the alumina support is impregnated with an impregnation solution in an amount approximately equal to the total pore volume of the alumina support and then the solvent is completely dried to support the components. The method for impregnating the alumina support with the zinc compound and phosphorus compound may be a one-step impregnation method in which each component is simultaneously impregnated, or a two-step impregnation method in which each component is individually impregnated.

When zinc compounds and phosphorus compounds are loaded using the impregnation method, the material is generally dried in a nitrogen stream, air stream, or vacuum at room temperature to 80°C to remove moisture to a certain extent (so that the LOI (loss on ignition) is 50% or less), and then dried in a drying oven in an air stream at 80 to 150°C for 10 minutes to 10 hours. It is then calcined in a calcination oven in an air stream at 300 to 700°C, more preferably 500 to 650°C, for 10 minutes to 10 hours, more preferably 3 to 6 hours.

When loading zinc compounds and phosphorus compounds onto an alumina carrier, the entire amount may be loaded using the kneading method, or a portion may be loaded using the kneading method and the remainder may be loaded using the impregnation method, or the entire amount may be loaded using the impregnation method, etc.

The phosphorus- and zinc-containing alumina support thus obtained is then loaded with Group 6 metals and cobalt.

In the hydrotreating catalyst of this embodiment, the raw material compound of the Group 6 metal to be supported on the phosphorus- and zinc-containing alumina support is preferably a molybdenum compound, such as molybdenum trioxide, molybdophosphoric acid, ammonium molybdate, or molybdic acid, with molybdophosphoric acid, molybdenum trioxide, and ammonium molybdate being preferred.

In the hydrotreating catalyst of this embodiment, examples of the cobalt raw material compound to be supported on the phosphorus- and zinc-containing alumina support include cobalt carbonate, cobalt acetate, cobalt nitrate, cobalt sulfate, and cobalt chloride, with cobalt carbonate and cobalt acetate being preferred, and cobalt carbonate being more preferred.

Methods for supporting a Group 6 metal or cobalt on a phosphorus- and zinc-containing alumina support include known methods such as impregnation, coprecipitation, kneading, deposition, and ion exchange. Examples of impregnation methods include an evaporation-to-dryness method, in which a phosphorus- and zinc-containing alumina support is immersed in an impregnation solution in excess of the total pore volume of the support and then the solvent is completely dried to support the hydrogenation-active component; an equilibrium adsorption method, in which a phosphorus- and zinc-containing alumina support is immersed in an impregnation solution in excess of the total pore volume of the support and then subjected to solid-liquid separation such as filtration to obtain a catalyst supporting the hydrogenation-active component; and a pore-filling method, in which a phosphorus- and zinc-containing alumina support is impregnated with an impregnation solution in an amount approximately equal to the total pore volume of the support and then the solvent is completely dried to support the hydrogenation-active component. The method for impregnating the phosphorus- and zinc-containing alumina support with the raw material compound of a Group 6 metal and the raw material compound of cobalt may be a one-step impregnation method in which these components are simultaneously impregnated, or a two-step impregnation method in which these components are individually impregnated.

Specific methods for supporting the Group 6 metal, cobalt, on the phosphorus- and zinc-containing alumina support include the following methods.
An impregnation solution containing a raw compound of a Group 6 metal and a raw compound of cobalt is prepared. During preparation, in order to promote dissolution of these compounds, heating (30 to 100°C) or the addition of an acid (nitric acid, phosphoric acid, or an organic acid (citric acid, acetic acid, malic acid, tartaric acid, etc.)) may be performed. That is, in this embodiment, when the Group 6 metal and cobalt are supported on the phosphorus-zinc-alumina support, phosphorus may be separately supported in addition to the phosphorus contained in the phosphorus-zinc-alumina support.

When supporting a Group 6 metal or cobalt on a phosphorus-zinc-alumina support, examples of phosphorus compounds that can be added separately include phosphorus-containing raw material compounds for hydrogenation active components such as molybdophosphoric acid, orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, with orthophosphoric acid being preferred. When supporting a Group 6 metal or cobalt on a phosphorus-zinc-alumina support, adding phosphorus separately can improve the dispersibility of the hydrogenation active component.

Next, the prepared impregnation solution is gradually added to the phosphorus- and zinc-containing alumina carrier to impregnate it uniformly. The impregnation time is preferably 1 minute to 5 hours, more preferably 5 minutes to 3 hours. The impregnation temperature is preferably 5 to 100°C, more preferably 10 to 80°C. There are no particular restrictions on the impregnation atmosphere, but air, nitrogen, and vacuum are all suitable.

The ratio of the mass of phosphorus kneaded into the support in terms of oxide to the mass of Group 6 metal in terms of oxide is preferably 0.25 or less. A ratio of 0.25 or less not only prevents a decrease in the surface area and pore volume of the catalyst, suppressing a decline in catalytic activity, but also prevents carbon deposition without increasing the amount of acid, thereby suppressing activity degradation.

When molybdenum is used as the Group 6 metal, the ratio of the mass of phosphorus mixed with the support in terms of oxide to the mass of molybdenum in terms of oxide is preferably 0.01 to 1.5, and more preferably 0.05 to 1.0. When the ratio of the mass of phosphorus mixed with the support in terms of oxide to the mass of molybdenum in terms of oxide is within the above range, cobalt and molybdenum can be blended together in a natural and harmonious manner.

In the method for producing a hydrotreating catalyst of this embodiment, after loading a raw compound of a Group 6 metal and a raw compound of cobalt, the impregnated body is first dehydrated to a certain extent (so that the LOI (loss on ignition) is 50% or less) in a nitrogen stream, an air stream, or a vacuum at 15 to 80°C. The resulting catalyst is then dried in a drying furnace in an air stream at 80 to 150°C for 10 minutes to 10 hours. The catalyst is then calcined in a calcining furnace in an air stream. The calcination temperature is preferably 300 to 700°C, more preferably 500 to 650°C. The calcination time is preferably 10 minutes to 10 hours, more preferably 3 hours or longer.

Examples of phosphorus contained in the hydrotreating catalyst of this embodiment include the phosphorus compound, phosphorus oxide (P ₂ O ₅ ) produced by the calcination, and a composite oxide of phosphorus and at least one element selected from the group consisting of aluminum, zinc, a Group 6 metal, and cobalt.

Examples of zinc contained in the hydrotreating catalyst of this embodiment include the zinc compound, zinc oxide (ZnO) produced by the calcination, and a composite oxide of zinc and at least one element selected from the group consisting of aluminum, phosphorus, Group 6 metals, and cobalt.

Examples of the Group 6 metal contained in the hydrotreating catalyst of this embodiment include raw material compounds of the Group 6 metal, oxides produced by the calcination (specific example: MoO ₃ ), and composite oxides of a Group 6 metal and at least one element selected from the group consisting of aluminum, zinc, phosphorus, and cobalt.

Examples of the cobalt contained in the hydrotreating catalyst of this embodiment include the cobalt raw material compound, the oxide produced by the calcination (specific example: CoO), and a composite oxide of cobalt and at least one element selected from the group consisting of aluminum, zinc, phosphorus, and Group 6 metals.

The hydrotreating catalyst of this embodiment prepared as described above preferably has a Group 6 metal sulfidity of 84 mol % or more, more preferably 86 mol % or more, as determined by XPS quantitative analysis, as represented by the following formula:
Group 6 metal sulfidity=[(M6(IV)/M6)×100]
where M6(IV) is the molar amount of Group 6 metal sulfide in the sulfided catalyst, and M6 is the molar amount of all Group 6 metal elements in the sulfided catalyst.
Here, the Group 6 metal sulfidity in the results of XPS quantitative analysis means the ratio (molar ratio) of the amount of Group 6 metal sulfide (M6(IV)) in the sulfurized catalyst to the total amount of Group 6 metal elements (M6).
For example, when molybdenum is used as the Group 6 metal in the present catalyst, the molybdenum sulfidity [(Mo(IV)/Mo)×100] in the results of XPS quantitative analysis means the ratio (molar ratio) of the amount of molybdenum disulfide (molar amount) in the sulfurized catalyst to the total amount of molybdenum. The molybdenum sulfidity is preferably 84 mol% or more, and more preferably 86 mol% or more.
The amount (molar amount) of Group 6 metal sulfide in the sulfurized catalyst can be obtained by heating the catalyst of the present invention at 5°C/min under a flow of a mixed gas of _H2S and _H2 (the content of _H2S relative to the total volume of the mixed gas is 4.8% by volume) at 50 ml/min, treating it at 300°C for 10 minutes to sulfurize it, purging it with high-purity helium gas for 10 minutes, and then performing XPS measurement while evacuating it to a vacuum.

Furthermore, in the catalyst of the present invention, the cobalt sulfidity as a result of XPS quantitative analysis, which is represented by the following formula, is preferably 60 mol % or more, more preferably 65 mol % or more.
Cobalt sulfidity = [(amount of cobalt sulfide/amount of cobalt element) x 100]
Here, the cobalt sulfidity in the XPS quantitative analysis results means the ratio (molar ratio) of the amount of cobalt sulfide (molar amount) to the amount of cobalt element (molar amount) in the sulfided catalyst.
That is, the cobalt sulfidity [(CoS/Co)×100] in the XPS quantitative analysis results means the ratio (molar ratio) of the amount of cobalt monosulfide to the total amount of cobalt in the sulfided catalyst, and the cobalt sulfidity is preferably 60 mol % or more, and more preferably 65 mol % or more.

<Method for producing hydrotreated heavy hydrocarbon oil (hydrotreating method for heavy hydrocarbon oil)>
The method for producing hydrotreated heavy hydrocarbon oil of this embodiment involves contacting the hydrotreating catalyst of the present invention with a heavy hydrocarbon oil containing sulfur compounds to carry out hydrotreatment under conditions of a water/oil ratio of 100 to 1000 Nm ³ /kL, a hydrogen partial pressure of 3.5 to 10 MPa, a reaction temperature of 330 to 430°C, and a liquid hourly space velocity (hereinafter also referred to as LHSV) of 0.2 to 2 hr ^-1 , thereby reducing the sulfur content in the heavy hydrocarbon oil and producing a hydrotreated heavy hydrocarbon oil.
The method ^for hydrotreating heavy hydrocarbon oil of this embodiment is a method for hydrotreating heavy hydrocarbon oil containing sulfur compounds, characterized by contacting the hydrotreating catalyst of the present invention with the heavy hydrocarbon oil containing sulfur compounds at a water/oil ratio of 100 to 1000 Nm ³ /kL, a hydrogen partial pressure of 3.5 to 10 MPa, a reaction temperature of 330 to 430°C, and a liquid hourly space velocity of 0.2 to 2 hr −1.

The hydrogen/oil ratio is preferably 100 to 1000 Nm ³ /kL, more preferably 175 to 925 Nm ³ /kL, and even more preferably 250 to 850 Nm ³ /kL. The hydrogen partial pressure is preferably 3.5 to 10 MPa, and more preferably 4 to 9 MPa. When the hydrogen partial pressure is equal to or higher than the lower limit of the above range, the hydrogenation reaction is likely to proceed.
The reaction temperature is preferably 330 to 430°C, more preferably 350 to 410°C. When the reaction temperature is equal to or higher than the lower limit of the above range, the catalytic activity can be fully exerted. When the reaction temperature is equal to or lower than the upper limit of the above range, the thermal cracking of the heavy hydrocarbon oil proceeds appropriately, while catalyst deterioration is unlikely to occur.
By reaction temperature is meant the average temperature of the catalyst bed.
The LHSV is preferably 0.2 to 2 hr ⁻¹ , more preferably 0.5 to 2 hr ⁻¹ .

Heavy hydrocarbon oils to be subjected to the method for producing hydrotreated heavy hydrocarbon oil (hydrotreating method for heavy hydrocarbon oil) of this embodiment include vacuum gas oil obtained by further vacuum distilling atmospheric distillation residue obtained by atmospheric distillation of crude oil in an atmospheric distillation unit in a vacuum distillation unit, atmospheric heavy oil obtained by atmospheric distillation of crude oil in an atmospheric distillation unit, heavy extracts which are particularly heavy oil components among oil components extracted and removed by solvent extraction of lubricating base oil such as hydrocracked heavy oil, atmospheric distillation residue, fluid catalytic cracking residue, thermal cracking heavy oil, and scraped oil, with vacuum gas oil, heavy extract, fluid catalytic cracking residue, and thermal cracking heavy oil being preferred, and vacuum gas oil being particularly preferred.
Hydrogenolysis catalysts for hydrocarbon oils contain active hydrogenation components, but it is common technical knowledge in the field that catalyst components other than the active hydrogenation components must be separately studied and optimized for each type of hydrocarbon oil. For example, when a hydrotreatment catalyst for so-called residual oils, such as atmospheric distillation residual oil or vacuum distillation residual oil, is used as a hydrotreatment catalyst for distillate oils such as vacuum gas oil, the molecules of vacuum gas oil are small relative to the catalyst pore size of the hydrotreatment catalyst for residues, which tends to lead to diffusion-limited reaction, making it difficult to obtain catalytic effects. Furthermore, when a hydrotreatment catalyst for relatively light oils, such as atmospheric distillation gas oil, is used as a hydrotreatment catalyst for relatively heavy oils, such as vacuum gas oil, uncalcined catalysts are often used for hydrotreatment of relatively light oils, and therefore activity is likely to deteriorate in high-temperature environments such as those used in the hydrotreatment of vacuum gas oil.
Examples of the catalyst configuration other than the hydrogenation active component include the specific surface area of the carrier, physical properties such as pore structure, the hydrogenation active component, and the types and contents of components (phosphorus, zinc, etc.) contained in the hydrotreating catalyst other than alumina.

The density of the heavy hydrocarbon oil to be subjected to the method for producing a hydrotreated heavy hydrocarbon oil (method for hydrotreating a heavy hydrocarbon oil) of this embodiment is preferably 0.91 to 1.10 g/cm ³ , and more preferably 0.95 to 1.05 g/cm ^3. The sulfur content is preferably 2 to 6 mass %, and more preferably 2 to 5 mass %. The nickel content is preferably 3 ppm or less, the vanadium content is preferably 3 ppm or less, and the asphaltene content is preferably 0.1 mass % or less.

The density of the hydrogenated heavy hydrocarbon oil produced by the method for producing hydrotreated heavy hydrocarbon oil (method for hydrotreating heavy hydrocarbon oil) of this embodiment is preferably 0.87 to 0.95 g/cm ³ , and more preferably 0.88 to 0.94 g/cm ^3. The sulfur content is preferably 1.0 to 3.5 mass %, and more preferably 1.2 to 3.4 mass %.

The hydrotreating catalyst of this embodiment may be activated by sulfiding in a reactor before use (i.e., prior to carrying out the hydrotreating method of this embodiment). This sulfiding is generally carried out at 200 to 400°C, preferably 250 to 350°C, in a hydrogen atmosphere at atmospheric or higher hydrogen partial pressure, by flowing a petroleum distillate containing sulfur compounds, to which a sulfiding agent such as dimethyl disulfide or carbon disulfide has been added, or hydrogen sulfide, through the hydrotreating catalyst.

Examples of zinc, phosphorus, Group 6 metal, and cobalt contained in the catalyst of this embodiment after the sulfurization treatment include zinc sulfide, phosphorus sulfide, sulfides of Group 6 metals, and cobalt sulfide.
Further examples include composite sulfides of two or more elements selected from the group consisting of zinc, phosphorus, Group 6 metals, cobalt, and aluminum.

By using the hydrotreating catalyst of this embodiment to hydrotreat heavy hydrocarbon oil, the hydrotreating process proceeds sufficiently and it becomes possible to reduce the sulfur compounds in the heavy hydrocarbon oil over a long period of time.

To carry out the hydrotreating method of this embodiment on a commercial scale, a fixed-bed, moving-bed, or fluidized-bed catalyst layer of the hydrotreating catalyst of this embodiment is formed in a reactor, a feedstock is introduced into this reactor, and hydrotreating is carried out under the conditions described above. Most commonly, a fixed-bed catalyst layer is formed in the reactor, the feedstock is introduced into the top of the reactor, passes through the fixed bed from top to bottom, and the product is discharged from the bottom of the reactor; alternatively, the feedstock is introduced into the bottom of the reactor, passes through the fixed bed from bottom to top, and the product is discharged from the top of the reactor.

The hydrotreating method of this embodiment may be a single-stage hydrotreating method in which the hydrotreating catalyst of this embodiment is packed into a single reactor, or a multi-stage continuous hydrotreating method in which the catalyst is packed into several reactors.

The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

<Physical and chemical properties of catalyst and carrier>
[1] Analysis of physical properties (specific surface area, pore volume, average pore diameter, and pore distribution)
a) Measurement method and equipment used:
The specific surface area was measured by the BET method using nitrogen adsorption. The nitrogen adsorption device used was a surface area measuring device (Belsorp 28) manufactured by Nippon Bell Co., Ltd.
The pore volume, average pore diameter, and pore distribution were measured by mercury intrusion porosimetry using a porosimeter (MICROMERITICS AUTO-PORE 9200, manufactured by Shimadzu Corporation).

b) Measurement principle of mercury porosimetry:
Mercury intrusion porosimetry is based on the law of capillary action. In the case of mercury and a cylindrical pore, this law is expressed by the following equation: The volume of mercury that penetrates into the pore is measured as a function of the applied pressure P. The surface tension of the mercury in the catalyst pore was set to 484 dyne/cm, and the contact angle was set to 130°.
D=-(1/P)4γcosθ
In the formula, D is the pore diameter, P is the applied pressure, γ is the surface tension, and θ is the contact angle.
Pore volume is the total volume of mercury that has entered the pores per gram of catalyst or support. Average pore diameter is the average value of D calculated as a function of P.
Pore size distribution is the distribution of D calculated as a function of P.

c) Measurement procedure:
1) Turn on the vacuum heating degassing device and confirm that the temperature is 400° C. and the vacuum level is 5×10 ⁻² Torr or less.
2) Place the empty sample burette in a vacuum heating degasser.
3) After confirming that the degree of vacuum has reached 5×10 ⁻² Torr or less, the sample burette is removed from the vacuum heating degasser with its cock closed, and after cooling, its weight is measured.
4) Place the sample (catalyst or carrier) in the sample buret.
5) The sample burette containing the sample is placed in a vacuum heating degasser, and is maintained for at least one hour after the degree of vacuum reaches 5×10 ⁻² Torr or less.
6) The sample burette containing the sample is removed from the vacuum heating degasser, cooled, and then weighed to determine the sample weight.
7) Place the sample in the AUTO-PORE 9200 cell.
8) Measure using AUTO-PORE 9200.

[2-1] Analysis of chemical composition a) Analysis method and equipment used:
Analysis of metals in the support and catalyst was carried out using an inductively coupled plasma emission spectrometry (ICPS-2000: manufactured by Shimadzu Corporation). Analysis of SO ₄ ^2- in the catalyst was carried out using a sulfur analyzer (S632: manufactured by LECO Corporation).
- Metal quantification was performed using the absolute calibration curve method.

b) Measurement procedure:
1) 0.05 g of catalyst or carrier, 1 mL of hydrochloric acid (50% by mass), one drop of hydrofluoric acid, and 1 mL of pure water were placed in a Uniseal and heated to dissolve.
2) After dissolution, the solution was transferred to a polypropylene measuring flask (50 mL), and pure water was added to the flask to make a total volume of 50 mL.
3) This solution was measured using ICPS-2000 or S632.

<Hydrotreatment of heavy hydrocarbon oil>
Hydrotreatment of vacuum gas oil having the following properties was carried out in the following manner. First, a catalyst was packed into a high-pressure flow reactor to form a fixed-bed catalyst layer, and pretreatment was carried out under the following conditions. Next, a mixed fluid of feed oil heated to the reaction temperature and hydrogen-containing gas was introduced from the top of the reactor, and hydrogenation reactions consisting of desulfurization and cracking reactions were carried out under the following conditions. The mixed fluid of the product oil and gas was discharged from the bottom of the reactor, and the product oil was separated in a gas-liquid separator.

Catalyst pretreatment conditions: drying at 120° C. for 3 hours under normal pressure.
The catalyst was pre-sulfided using vacuum diesel fuel at a hydrogen partial pressure of 10.3 MPa and 370° C. for 12 hours, after which the feedstock oil for activity evaluation was used.

Reaction conditions:
Pressure (hydrogen partial pressure): 4.9 MPa
Liquid space velocity: 0.95hr ^-1
Hydrogen/oil ratio: 240 Nm ³ /kL
Reaction temperature: set so that the sulfur content in the produced oil is 0.28% by mass

Properties of feedstock oil:
Oil type: Vacuum gas oil (Arabian heavy, Das blend)
Density (15°C); 0.9295g/ ^cm3
Sulfur content: 2.72% by mass
Nitrogen content: 0.092% by mass
Residual carbon content: 0.81% by mass

[Production Example 1]
1.5 L of a 12% by weight aqueous sulfuric acid solution was added to 100 L of pure water in a stirring vessel, heated to 95°C, and vigorously stirred with a stirring blade for 5 minutes. 3.9 L of sodium aluminate with an alumina concentration of 70 g/L was then added to prepare aluminum hydroxide, followed by stirring with a stirring blade for 24 hours. The resulting slurry was placed in a filter and filtered to remove moisture. The resulting gel was then washed with pure water until SO ₄ ^2- and Na ⁺ were no longer detectable in the filtrate. The washed gel was then mixed with pure water to form a homogeneous slurry, which was then placed in a compression filter. The slurry was sandwiched between filter plates via a filter cloth, and dehydrated by squeezing the filter plates. Filtration was discontinued when the moisture content of the cake reached 80% through dehydration. This cake was placed in a heated kneader (set temperature 80°C) and thoroughly kneaded to homogenize. After that, phosphoric acid and zinc oxide were added, and further kneaded to homogenize. The kneaded cake was placed in an extrusion molding machine to form a four-leaf-shaped extrusion with a major axis of 1.3 mm and a minor axis of 1.1 mm. This molding was dried and then calcined at 600°C for 4 hours to obtain a phosphorus- and zinc-containing alumina carrier (carrier A).
Table 1 shows the phosphorus and zinc contents of the carrier A calculated as oxides, the specific surface area, the pore volume, and the average pore diameter.

[Production Example 2]
An alumina carrier (carrier B) was obtained in the same manner as in Production Example 2, except that phosphoric acid and zinc oxide were not added.
Table 1 shows the phosphorus and zinc contents of the carrier B calculated as oxides, the specific surface area, the pore volume, and the average pore diameter.

[Example 1]
50.00 g of Carrier A produced in Production Example 1 was placed in an eggplant-shaped flask, and a solution prepared by dissolving 5.5114 g of cobalt carbonate, 19.0187 g of molybdophosphoric acid, and 1.9418 g of orthophosphoric acid in 40.5 g of ion-exchanged water was added thereto using a pipette. The mixture was immersed at 25°C for 1 hour, air-dried in a nitrogen stream, dried at 120°C in a muffle furnace for 1 hour, and then calcined at 500°C for 4 hours to obtain Catalyst A. Table ₂ shows the contents of phosphorus, zinc, cobalt, and molybdenum (calculated on a catalyst basis in terms of oxides), the contents of _SO42- ^, _Na2O , and _Fe2O3 , the specific surface area, pore volume, average pore diameter, and the ratio of the volume of pores having a pore diameter of the average pore diameter ±1.5 nm to the total pore volume of Catalyst A. In Table 2, "pore distribution" means "the ratio of the volume of pores having a pore diameter of the average pore diameter ±1.5 nm to the total pore volume."
Using catalyst A, heavy hydrocarbon oil was hydrotreated by adjusting the reaction temperature so that the sulfur content in the product oil would be 0.28% by mass. The reaction temperatures from 1 day to 17 days after the start of the reaction are shown in Table 3.

[Comparative Example 1]
Catalyst B was obtained in the same manner as in Example 1, except that carrier B was used instead of carrier A. Table 2 shows the catalyst-based oxide-equivalent contents of phosphorus, zinc, cobalt, and molybdenum for catalyst B, the specific surface area, pore volume, average pore diameter, and the ratio of the volume of pores having pore diameters within the average pore diameter ±1.5 nm to the total pore volume.
Using catalyst B, heavy hydrocarbon oil was hydrotreated by adjusting the reaction temperature so that the sulfur content in the product oil would be 0.28% by mass. The reaction temperatures from 1 day to 12 days after the start of the reaction are shown in Table 3.

[Comparative Example 2]
60.00 g of Carrier A produced in Production Example 1 was placed in a recovery flask, and a solution prepared by dissolving 11.1 g of nickel nitrate hexahydrate, 10.5 g of ammonium molybdate tetrahydrate, and 13.8 g of citric acid monohydrate in 36.1 g of ion-exchanged water was added thereto using a pipette. The mixture was immersed at 25°C for 1 hour, then air-dried in a nitrogen stream, dried at 120°C for 1 hour in a muffle furnace, and calcined at 300°C for 1 hour and then at 500°C for 4 hours to obtain Catalyst C. Table _{2 shows} the catalyst-based oxide-equivalent contents of _{phosphorus, zinc, nickel, and molybdenum, the contents of SO42-, Na2O ,} ^and _Fe2O3 , the specific surface area, pore volume, average pore diameter, and the ratio of the volume of pores having a pore diameter of the average pore diameter ±1.5 nm to the total pore volume.
Using catalyst C, the reaction temperature was adjusted so that the sulfur content in the product oil would be 0.28 mass%, and heavy hydrocarbon oil was hydrotreated. The reaction temperatures from 1 day to 17 days after the start of the reaction are shown in Table 3.

As shown in Table 3, the hydrotreating catalyst of Example 1 of the present invention had a lower reaction temperature at the initial stage of the reaction than the zinc-free hydrotreating catalyst of Comparative Example 1, and there was no need to increase the reaction temperature even 17 days after the start of the reaction. In other words, it was found that the hydrotreating catalyst of Example 1 had a higher hydrotreating activity than the hydrogenation catalyst of Comparative Example 1, and the activity was less likely to decrease.
Furthermore, the hydrotreating catalyst of Example 1 of the present invention had a lower reaction temperature at the initial stage of the reaction than the hydrotreating catalyst of Comparative Example 2, which did not contain cobalt, and there was no need to increase the reaction temperature even 17 days after the start of the reaction. The reaction temperature at the initial stage of the reaction was thought to be largely due to the fact that the hydrotreating catalyst of Example 1 carried a larger amount of molybdenum than the hydrotreating catalyst of Comparative Example 2. On the other hand, the increase in reaction temperature was thought to be due to the fact that the hydrotreating catalyst of Comparative Example 2 carried nickel instead of cobalt.

The heavy hydrocarbon oil hydrotreating catalyst of the present invention is useful because it can be used to reduce the sulfur content in heavy hydrocarbon oil.

Claims (3)

a phosphorus- and zinc-containing alumina carrier containing 0.1 to 4 mass % of phosphorus, calculated as oxide, based on the carrier, and 1 to 8 mass % of zinc, calculated as oxide, based on the carrier;
The vacuum gas oil hydrotreating catalyst comprises a carrier on which at least one metal selected from Group 6 of the periodic table is supported in an amount of 8 to 30 mass % in terms of oxide, based on the catalyst, and cobalt in an amount of 2 to 8 mass % in terms of oxide, based on the catalyst. The method for producing a vacuum gas oil hydrotreating catalyst includes a step of supporting at least one metal selected from Group 6 of the periodic table on a phosphorus- and zinc-containing alumina support, the alumina support containing phosphorus in an amount of 0.1 to 4 mass % in terms of oxide, based on the support, and zinc in an amount of 1 to 8 mass % in terms of oxide, based on the support, so that the metal contains 8 to 30 mass % in terms of oxide, based on the catalyst, and cobalt in an amount of 2 to 8 mass % in terms of oxide , based on the catalyst. A method for hydrotreating vacuum gas oil, comprising contacting the vacuum gas oil with the vacuum gas oil hydrotreating catalyst according to claim 1 at a hydrogen/ oil ratio of 100 to 1000 Nm ³ /kL, a hydrogen partial pressure of 3.5 to 10 MPa, a temperature of 330 to 430°C, and a liquid hourly space velocity of 0.2 to 2 hr ^-1 .