JP2014111233A - Hydrodesulfurization catalyst of hydrocarbon oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst capable of conducting a hydrogenation treatment with a prescribed desulfurization rate under a relatively moderate desulfurization condition to a wide range of hydrocarbon oils.SOLUTION: There is provided a hydrodesulfurization catalyst of hydrocarbon oil, carrying cobalt and the like on alumina of 80 to 99 mass% and HY zeolite of 1 to 20 mass% and containing cobalt of 3 to 6 mass%, molybdenum of 16 to 24 mass% and phosphorus of 0.8 to 4.5 mass% in a catalyst basis and in terms of oxides, and having a specific surface area of 210 to 280 m/g, a pore volume of 0.3 to 0.6 ml/g, an average pore diameter in a pore distribution of 75 to 95 Å, the pore volume in a range of the average pore diameter being ±15 Å of at least 75% of the total pore volume, the HY zeolite having (a) SiO/AlO(molar ratio) of 3 to 10, (b) a crystal lattice constant of 2.435 to 2.465 nm, (c) a mole ratio to all Al of Al in the zeolite skeleton of 0.4 to 1, and (d) a crystallite diameter of 30 to 100 nm.

Description

  The present invention relates to a hydrodesulfurization catalyst for hydrocarbon oil. More specifically, the present invention relates to a hydrodesulfurization catalyst having an excellent activity capable of reducing the sulfur content in hydrocarbon oils such as kerosene, light oil and vacuum gas oil under a relatively mild condition over a long period of time.

  The hydrocarbon oil fraction obtained by distillation or cracking of crude oil generally contains sulfur compounds, and when these oils are used as fuel, air pollutants such as sulfur oxides resulting from the sulfur compounds are released into the atmosphere. Released into. For this reason, with increasing awareness of environmental problems, regulations on air pollution are becoming stricter, and there is a strong demand for reducing the sulfur content in fuel oil.

  As a technology for reducing sulfur compounds contained in this fuel oil, hydrodesulfurization treatment of a hydrocarbon oil as a raw material is usually carried out in a hydrodesulfurization apparatus using a catalyst having desulfurization activity. Desulfurization catalysts have been proposed. For example, as a desulfurization catalyst, an inorganic oxide carrier such as alumina that is supported by a hydrogenation active metal component such as molybdenum, tungsten, cobalt, nickel, etc. is used, and in order to further improve the catalyst performance, Improvement of the carrier, examination of the supporting component, and a supporting method of the supporting component have been studied (for example, see Patent Document 1).

  The conventional desulfurization level (produced oil sulfur content 0.2 to 0.05 mass%) can be easily achieved with the current desulfurization technology, but until the sulfur content becomes lower (produced oil sulfur Min. 0.04 mass% or less) Desulfurization becomes abruptly difficult. This is because the position of the alkyl substituent such as 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) is in the vicinity of the sulfur atom, so the desulfurization active site of the catalyst This is because a sulfur compound that causes steric hindrance when contacting with the catalyst makes desulfurization extremely difficult.

  Under such circumstances, development of a desulfurization technique for removing more sulfur content in light oil is being emphasized. Usually, in order to increase the reduction amount of the sulfur content in light oil, the operating conditions of hydrodesulfurization, for example, the reaction temperature, the liquid space velocity, and the like are harsh. However, when the reaction temperature is raised, carbonaceous matter is deposited on the catalyst and the activity of the catalyst is rapidly reduced.When the liquid space velocity is lowered, the desulfurization ability is improved, but the purification treatment capacity is lowered. There is a need to scale. Moreover, such severe operating conditions also have an adverse effect on properties such as hue and storage stability. Therefore, the best way to achieve gas oil desulfurization under milder conditions without harsh operating conditions is to develop a catalyst with significantly superior desulfurization activity.

  On the other hand, depending on the use situation such as kerosene and light oil, there is a catalyst that can be used for a longer period of time while having a desulfurization activity that can secure a predetermined degree of desulfurization rate, that is, a catalyst with longer life. It may be necessary. Furthermore, if the same catalyst can be used to desulfurize kerosene, light oil, and vacuum gas oil, it is possible to more efficiently manage the catalyst and equipment used.

JP 2000-342976 A

  The present invention is a catalyst that has a predetermined desulfurization activity, has a long life, and is capable of hydrotreating a wide range of hydrocarbon oils from naphtha to vacuum gas oil under relatively mild desulfurization conditions. The purpose is to provide.

  Under these circumstances, as a result of intensive studies, the present inventors have conducted a hydrodesulfurization reaction by combining a zeolite having various physical properties with an alumina-based support. Among these, hydrodesulfurization reaction is more efficient with respect to various hydrocarbon oils such as kerosene, light oil and heavy light oil by using HY zeolite having specific physical properties than when using other zeolites. I got new knowledge to go on. As a result of further investigation based on this knowledge, the above object is obtained by combining HY zeolite having predetermined physical properties with a support based on alumina and controlling the physical properties of the catalyst such as the average pore diameter. Has been found to be able to be achieved, and the present invention has been completed.

That is, the first aspect of the present invention is a catalyst in which cobalt, molybdenum and phosphorus are supported on a composite oxide carrier containing 80 to 99% by mass of alumina and 1 to 20% by mass of HY zeolite. The specific surface area measured by the nitrogen adsorption method containing 3 to 6% by mass of cobalt, 16 to 24% by mass of molybdenum, and 0.8 to 4.5% by mass of phosphorus in terms of catalyst and oxide. Of 10 to 280 m ² / g, pore volume measured by mercury intrusion method is 0.3 to 0.6 ml / g, average pore diameter in pore distribution measured by mercury intrusion method is 75 to 95 mm, average pore The pore volume in the range of ± 15 mm in diameter is at least 75% of the total pore volume;
_{(A) SiO 2 / Al 2} O 3 ( molar ratio), 3-10,
(B) the crystal lattice constant is 2.435 to 2.465 nm,
(C) The molar ratio of Al in the zeolite framework to the total Al is 0.4 to 1, and (d) the crystallite diameter is 30 to 100 nm,
This is a hydrodesulfurization catalyst for hydrocarbon oil.

Since the hydrodesulfurization catalyst for hydrocarbon oil according to the present invention has a high desulfurization activity, the sulfur content in the gas oil fraction can be greatly reduced.
Further, the hydrodesulfurization catalyst for hydrocarbon oil according to the present invention can make the reaction conditions substantially the same or milder than the reaction conditions in the conventional hydrotreatment, so that the conventional apparatus is greatly modified. And can be diverted to a conventionally used hydrodesulfurization catalyst.
Furthermore, by using the hydrodesulfurization catalyst for hydrocarbon oil according to the present invention, a light oil base material having a low sulfur content can be easily supplied.

In catalysts A to D and catalyst a, it is the figure which showed the relationship between the crystallite diameter (nm) of the zeolite contained in a catalyst, and a desulfurization reaction rate constant (Ks).

  The hydrodesulfurization catalyst for hydrocarbon oil according to the present invention (hereinafter sometimes referred to as “catalyst according to the present invention”) includes a cobalt oxide support containing alumina and HY zeolite having specific physical properties. , Molybdenum, and phosphorus, a hydrodesulfurization catalyst for hydrocarbon oils having specific surface area, pore volume, and average pore diameter within specific ranges. Even under relatively mild desulfurization conditions by using an alumina support containing HY zeolite having specific physical properties and controlling physical properties such as specific surface area, pore volume and average pore diameter within a specific range. Thus, it is possible to obtain a long-life hydrodesulfurization catalyst that can perform a hydrogenation treatment at a sufficient desulfurization rate.

<HY zeolite>
The HY zeolite used in the catalyst according to the present invention has the following physical properties (a) to (d).
_{(A) SiO 2 / Al 2} O 3 ( molar ratio), 3-10,
(B) the crystal lattice constant is 2.435 to 2.465 nm,
(C) The molar ratio of Al in the zeolite framework to the total Al is 0.4 to 1, and (d) the crystallite diameter is 30 to 100 nm.

(A) SiO ₂ / Al ₂ O ₃ (molar ratio)
SiO ₂ / Al ₂ O ₃ (molar ratio) can be measured by chemical composition analysis by ICP analysis.
Bulk SiO ₂ / Al ₂ O ₃ (molar ratio) by chemical composition analysis of HY zeolite used in the catalyst according to the present invention is 3 to 10, preferably 5 to 8. When the SiO ₂ / Al ₂ O ₃ (molar ratio) is 3 or more, a sufficient amount of active sites can be provided, and the isomerization of the difficult-to-desorb substance alkyl group and the hydrogenation of the benzene ring are sufficiently performed. Is called. _Further, by SiO 2 / _Al 2 _{O 3} (molar ratio) is 10 or less, decomposition of the raw material oil (hydrocarbon oil) hardly proceeds, reduction of liquid yield can be suppressed.
The HY zeolite used in the present invention has basically the same crystal structure as natural faujasite and has the following composition as an oxide.

(B) Crystal lattice constant The crystal lattice constant (unit cell dimension) of HY zeolite can be measured by an X-ray diffractometer (XRD). Here, “the crystal lattice constant of HY zeolite” indicates the size of the unit unit constituting the zeolite.
The crystal lattice constant of the HY zeolite used in the present invention is 2.435 to 2.465 nm, preferably 2.440 to 2.460 nm. If the crystal lattice constant is 2.435 nm or more, the Al number (number of aluminum atoms) necessary to promote isomerization of the alkyl group of the difficult-to-desorb substance and hydrogenation of the benzene ring is appropriate, and it is 2.465 nm or less. If so, the decomposition of the raw material oil on the acid point is suppressed, and the carbon deposition that is the main factor of the decrease in activity can be suppressed.

(C) Molar ratio of Al in zeolite framework to total Al The number of moles of aluminum atoms in zeolite framework relative to all aluminum atoms in zeolite is expressed by the following formula from the SiO ₂ / Al ₂ O ₃ ratio and crystal lattice constant determined by chemical composition analysis. It can be calculated using (A) to (C). In addition, Formula (A) is H.264. K. Beyeretal. , J .; Chem. Soc. , Faraday Trans. 1, (81), 2899 (1985). Is adopted.

Formula (A): N _A1 = (ao-2.425) /0.000868
In the formula (A), ao: crystal lattice constant / nm,
N _Al : Number of Al atoms per unit cell,
2.425: Crystal lattice constant when all Al atoms in the unit cell skeleton are desorbed outside the skeleton,
0.000868: A calculated value obtained by experiment, and a slope when ao and N _Al are arranged by a linear equation (ao = 0.000868N _Al +2.425).

Formula (B): [(Si / Al) calculation formula] = (192-N _Al ) / N _Al
In formula (B), 192: number of (Si + Al) atoms per crystal lattice constant of Y-type zeolite.

Formula (C): [Zeolite framework Al] / [total Al] = [(Si / Al) chemical composition analysis value] / [(Si / Al) calculation formula]

  The molar ratio of aluminum atoms in the zeolite framework to the total aluminum atoms of the HY zeolite used in the present invention ([Al in zeolite framework] / [total Al]) is 0.4 to 1, preferably 0.4 to 0. .9. The greater the amount of alumina in the zeolite framework, the lower the stability of the zeolite and the more likely it is to deteriorate during actual operation, so that the acid sites necessary for isomerization and hydrogenation do not appear. If [Zeolite framework Al] / [total Al] is 0.4 or more, the deterioration of the liquid yield due to the decomposition reaction can be suppressed if it is 1 or less without impairing the isomerization or hydrogenation promoting function.

(D) Crystallite diameter In the catalyst according to the present invention, the crystallite diameter of the HY zeolite to be used is measured by an X-ray diffractometer and defined as (1) to (4) below.
(1) A diffraction peak of zeolite is calculated from an X-ray diffractometer.
(2) From the peaks corresponding to the (533) plane, the (642) plane, and the (555) plane, the half width of each plane is calculated.
(3) The half widths of the (533) plane, (642) plane, and (555) plane are substituted into Scherrer's formula (formula (D)) to determine the size of each plane.
(4) The average value of the three surfaces obtained in (3) is defined as the zeolite crystal diameter.

Formula (D): D = Kλ / βcos θ
In the formula (D), D: crystallite diameter (Å) of zeolite,
K: Scherrer constant,
λ: X-ray wavelength (nm),
β: full width at half maximum (rad),
θ: diffraction angle (°).

  The crystallite diameter of the HY zeolite used in the present invention obtained from the formula (D) is 30 to 100 nm, preferably 45 to 95 nm. By making the crystallite diameter of the zeolite within the above range, it is possible to suppress the carbon precipitation, which is the main factor for the decrease in activity, without impairing the isomerization and hydrogenation promoting function, and the liquid yield by the decomposition reaction Reduction can be suppressed.

<Composite oxide support>
In the catalyst according to the present invention, an inorganic oxide containing alumina as a main component and containing the HY zeolite is used as a carrier. Specifically, the catalyst according to the present invention comprises, as an essential component, a composite oxide support containing 80 to 99% by mass of alumina and 1 to 20% by mass of the HY zeolite, based on the support. Co), molybdenum (Mo), and a catalyst carrying phosphorus.

  The compounding amount of the HY zeolite in the composite oxide carrier is preferably 2 to 10% by mass, more preferably 4 to 8% by mass, based on the carrier. If the blending amount of HY zeolite is too small or too large, it is difficult to mold the catalyst. Moreover, when there are too few, there exists a possibility that provision of the Bronsted acid point and Lewis acid point which are the acid points on a catalyst may become inadequate, and when too large, there exists a possibility that high dispersion | distribution of Mo may be suppressed.

Various aluminas such as α-alumina, β-alumina, γ-alumina, and δ-alumina can be used as the alumina used in the catalyst carrier according to the present invention, but the porous alumina has a high specific surface area. Of these, γ-alumina is suitable. The purity of alumina is about 98% by mass or more, preferably about 99% by mass or more. Examples of the impurities in alumina include SO ₄ ²⁻ , Cl ⁻ , Fe ₂ O ₃ , Na ₂ O, and the like, but these impurities are preferably as small as possible. Specifically, the total amount of impurities is preferably 2% by mass or less, preferably 1% by mass or less. For each component, SO ₄ ²⁻ <1.5% by mass, Cl ⁻ , Fe ₂ O ₃ , Na ₂ O. <0.1% by mass is preferred.

The specific surface area, pore volume, and average pore diameter of the alumina support (composite oxide support) containing the HY zeolite are not particularly limited, but in order to obtain a catalyst having high hydrodesulfurization activity for light oil, Surface area is about 240-500 m ² / g, preferably about 300-450 m ² / g, pore volume is about 0.55-0.9 ml / g, preferably about 0.65-0.8 ml / g, average fine A hole diameter of about 60 to 120 mm, preferably about 65 to 90 mm is suitable.

In the composite oxide support, when the specific surface area is about 240 m ² / g or more, the dispersibility of the active metal is improved, and a catalyst having a high desulfurization activity is obtained. In addition, when the pore diameter of the catalyst is small, the diffusion of sulfur compounds into the catalyst pores becomes insufficient and the desulfurization activity may be reduced, but the specific surface area is about 500 m ² / g or less. Therefore, there is no fear that the pore diameter becomes extremely small, and the pore diameter of the catalyst does not become too small.

  In the composite oxide support, when too little solvent enters the pore volume, the solubility of the active metal compound is deteriorated, the dispersibility of the metal is lowered, and there is a possibility that the catalyst becomes a low activity catalyst. When the pore volume is about 0.55 ml / g or more, when a catalyst is prepared by a normal impregnation method, a sufficient amount of solvent can enter the pore volume. Further, in order to increase the solubility of the active metal compound, there is a method of adding a large amount of acid such as nitric acid. However, when the amount of acid added is too large, the specific surface area of the support is extremely reduced and the desulfurization performance is reduced. May decrease. When the pore volume of the composite oxide support is about 0.9 ml / g or less, a catalyst having a sufficient specific surface area, good dispersibility of active metals and high desulfurization activity can be obtained.

  Moreover, when the pore diameter of the catalyst is small, the diffusion of sulfur compounds into the catalyst pores becomes insufficient, and the desulfurization activity may be reduced. When the composite oxide support has a pore diameter of about 60 mm or more, a catalyst having a sufficiently large pore diameter can be obtained by supporting the active metal. On the other hand, if the specific surface area of the catalyst is small, the dispersibility of the active metal is deteriorated and the desulfurization activity may be reduced. When the pore diameter of the composite oxide support is about 120 mm or less, a catalyst having a sufficient specific surface area can be obtained.

  In addition to alumina and HY zeolite, the composite oxide support may contain inorganic oxides such as boria, silica, silica-alumina, titania, and zirconia as long as the above-mentioned support physical properties and final catalyst physical properties are satisfied. Good.

<Hydrodesulfurization catalyst for hydrocarbon oil>
Examples of the Co compound supported on the composite oxide carrier include carbonates, acetates, nitrates, sulfates, and chlorides, preferably carbonates and acetates, more preferably carbonates.
Examples of the Mo compound supported on the composite oxide carrier include molybdenum trioxide, molybdophosphoric acid, ammonium molybdate, molybdic acid, and the like, preferably molybdophosphoric acid and molybdenum trioxide.

  The phosphorus to be supported on the composite oxide carrier is derived from these phosphorus compounds when using a compound containing phosphorus as a Co compound or Mo compound (phosphorus compound) such as molybdophosphoric acid. May be. Further, when a phosphorus compound is not used as the Co compound or the Mo compound, or when only a phosphorus derived from these phosphorus compounds is insufficient for the prescribed phosphorus amount, another phosphorus source is further used. Examples of other phosphorus sources include various phosphoric acids. Specific examples include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, and polyphosphoric acid, and orthophosphoric acid is particularly preferable.

Among these active ingredients, the content of Co is 3 to 6% by mass, preferably about 3.5 to 6% by mass in terms of catalyst and oxide. If the Co content is too low, there may be insufficient active sites attributable to Co. If the Co content is too high, the dispersibility of the active metal is poor due to aggregation of the Co compound. In addition, Co ₃ O ₄ species (present as Co ₉ S ₈ species after catalytic sulfidation and during hydrogenation) and Co spinel species incorporated into the lattice of the support are generated as inactive precursors. The catalytic activity may be reduced. By setting the Co content within the above range, it has a sufficient amount of active sites attributable to Co, has good dispersibility of Co, has a low content of inactive Co compounds, and has high desulfurization activity. A catalyst is obtained.

  The Mo content is 16 to 24% by mass, preferably about 18 to 22% by mass in terms of catalyst and oxide. When there is too little content of Mo, there exists a possibility that it may be inadequate to express the effect resulting from Mo. On the other hand, when the Mo content is too large, the dispersibility of the active metal is deteriorated due to the aggregation of Mo, and the limit of the active metal content to be efficiently dispersed is exceeded, or the catalyst surface area is greatly reduced. As a result, the catalytic activity is not improved. By setting the Mo content within the above range, it is possible to obtain a catalyst having a high desulfurization activity that exhibits a sufficient effect due to Mo, has good Mo dispersibility, and has a sufficient catalyst surface area.

  Phosphorus is added as a component for improving the quality of active sites in order to improve the desulfurization activity per active metal amount, and precisely creates a highly active Co-Mo-S phase (desulfurization active site). Play a role. That is, phosphorus acts to improve the acid properties of the catalyst, and when the catalyst exhibits a suitable acid property value, the dispersibility of the active ingredient is improved and the amount of acid sites on the support is optimal. It promotes adsorption of sulfur compounds and improves the hydrodesulfurization activity of sulfur compounds.

  The phosphorus content is 0.8 to 4.5% by mass, preferably about 1.0 to 4% by mass in terms of catalyst and oxide. When there is too little content of phosphorus, the effect | action of said phosphorus may not fully express, and there exists a possibility that the sulfur content in a light oil fraction cannot be removed efficiently. On the other hand, when the content of phosphorus is too large, the above-described action of phosphorus is saturated, and further, the surface area and pore volume of the catalyst are reduced, and the desulfurization activity is lowered. By making the content of phosphorus within the above range, the above-mentioned action of phosphorus can be sufficiently exerted while suppressing the reduction of the surface area and pore volume of the catalyst.

In the above contents of the Co, Mo, and phosphorus components, the optimum mass ratio of Co and Mo, which are active metals, is a value of [CoO] / [CoO + MoO ₃ ] and is about 0.12 to 0.24. The optimum mass ratio of Mo, which is an active metal, and phosphorus, which is an acid property improving component of the catalyst, is about 0.05 to 0.25 in terms of [P ₂ O ₅ ] / [MoO ₃ ]. Is preferred.

When the mass ratio of Co and Mo is too small at the value of [CoO] / [CoO + MoO ₃ ], it is considered that a Co—Mo—S phase considered as an active site of desulfurization cannot be sufficiently generated, and desulfurization activity is low. Does not improve. On the other hand, if the above value is too large, there is a possibility that useless Co species (Co ₉ S ₈ species or Co spinel species incorporated in the lattice of the support) that are not involved in the activity may be generated, and the catalytic activity Decreases. Since the mass ratio of Co and Mo is about 0.12 to 0.24 at the above value, the Co—Mo—S phase is sufficiently generated while suppressing the generation of inert Co species, A catalyst having high desulfurization activity is obtained.

When the mass ratio of phosphorus and Mo is too small at a value of [P ₂ O ₅ ] / [MoO ₃ ], Co and Mo cannot be integrated as a matter of course, and Co-Mo which is the active point of desulfurization is finally obtained. It is difficult to obtain a -S phase, and the catalyst becomes low in activity. On the other hand, if the above value is too large, the surface area and pore volume of the catalyst are reduced, and not only the activity of the catalyst is decreased, but also the acid amount is increased, which causes carbon deposition and deteriorates the activity. It becomes easy to cause. When the mass ratio of phosphorus and Mo is about 0.05 to 0.25 as described above, the Co—Mo—S phase is sufficiently produced while suppressing the decrease in the surface area and pore volume of the catalyst and the carbon deposition. As a result, a catalyst having high desulfurization activity can be obtained.

The catalyst according to the present invention is first impregnated with a solution prepared by complexing the HY zeolite with alumina and dissolving the compound of each component in a solvent such as water and acid in the obtained complex oxide support. Can be prepared.
Examples of a method for combining alumina and the HY zeolite include a coprecipitation method and a kneading method.

The method of impregnating the composite oxide carrier with Co, Mo, and phosphorus components is preferably a one-stage impregnation method in which these components are impregnated simultaneously. This is because the one-stage impregnation method is considered advantageous from the standpoint of catalyst characteristics such as the number of desulfurization active points, acid properties, and pores, or operability. That is, according to the one-step impregnation method, Co and Mo are naturally integrated and taken into the support, so that the Co—Mo—S phase, which is the active point of desulfurization, can be greatly increased. At this time, if the phosphorus component is present in the impregnation solution, the natural integration of Co and Mo is promoted. On the other hand, in the method in which Co and Mo are impregnated in two stages, Co and Mo may not be sufficiently integrated, and eventually it becomes difficult to form a Co—Mo—S phase that is an active point of desulfurization. For example, Co may be a Co ₃ O ₄ species that is an inactive precursor as described above, or a Co spinel species that is not involved in the activity incorporated in the lattice of the carrier.

A specific method for supporting Co and Mo on the carrier is as follows.
First, a solution containing each of Co, Mo, and phosphorus compounds (when the Mo compound contains phosphorus, the phosphorus compound is not added, or an appropriate amount of the phosphorus compound is added) is prepared. During the preparation of the solution, heating (about 30 to 100 ° C.) or addition of an acid may be performed in order to promote dissolution of these compounds. Examples of the acid include nitric acid and organic acids such as citric acid, acetic acid, malic acid, and tartaric acid.
Next, the prepared solution is gradually added and impregnated into the composite oxide support in a uniform manner. The impregnation time is about 1 minute to 5 hours, preferably about 5 minutes to 3 hours, the temperature is about 5 to 100 ° C., preferably about 10 to 80 ° C., and the atmosphere is not particularly limited, but in air, nitrogen, or vacuum Is suitable.

  After impregnation support, water is removed to some extent (from about 50% or less LOI << Loss on ignition >>) in a nitrogen stream, air stream, or vacuum at room temperature to about 80 ° C., and a drying furnace, air stream Medium is dried at about 80 to 150 ° C. for about 10 minutes to 10 hours. Next, firing is performed at about 300 to 700 ° C. for about 10 minutes to 10 hours in a firing furnace and an air stream.

  The distribution state of the active metal in the catalyst according to the present invention is preferably a uniform type in which the active metal is uniformly distributed in the catalyst.

  The catalyst according to the present invention prepared as described above has a specific surface area, a pore volume and an average pore diameter in order to increase the hydrogenation activity and desulfurization activity for kerosene, light oil, heavy gas oil fraction, etc. The following values need to be controlled.

Nitrogen adsorption method of the catalyst according to the present invention measured specific surface area (BET "Braunauer-Emmett-Tailor specific surface area" method) (BET specific surface area) is, 210~280m ² / g, preferably about 220~250m ² / g. When the BET specific surface area is too small, the dispersibility of the active metal is deteriorated and the desulfurization activity is lowered, and when the BET specific surface area is too large, the pore diameter becomes extremely small. In the hydrotreating process, the diffusion of sulfur compounds into the catalyst pores becomes insufficient, and the desulfurization activity decreases. By setting the BET specific surface area of the catalyst within the above range, the dispersibility of the active metal can be good, the pore diameter can be made sufficiently large, and a catalyst having high desulfurization activity can be obtained.

  The pore volume measured by the mercury intrusion method of the catalyst according to the present invention is 0.3 to 0.6 ml / g, preferably about 0.35 to 0.5 ml / g. If the pore volume is too small, the diffusion of sulfur compounds in the catalyst pores will be insufficient during the hydrotreatment, resulting in insufficient desulfurization activity. If the pore volume is too large, the catalyst The specific surface area of the catalyst becomes extremely small, the dispersibility of the active metal is lowered, and the catalyst has a low desulfurization activity. By setting the pore volume of the catalyst within the above range, it is possible to obtain a catalyst having a high desulfurization activity in which the sulfur compound can sufficiently diffuse in the catalyst pores and has a sufficient specific surface area.

  The average pore diameter in the pore distribution measured by the mercury intrusion method of the catalyst according to the present invention is 75 to 95 mm, preferably about 80 to 90 mm. If the average pore diameter is too small, the reactant will not easily diffuse into the pores, so the desulfurization reaction will not proceed efficiently, and if the average pore diameter is too large, diffusion within the pores will occur. Although the properties are good, since the surface area in the pores is reduced, the effective specific surface area of the catalyst is reduced and the activity is lowered. By setting the average pore diameter of the catalyst within the above range, it is possible to obtain a catalyst in which the effective specific surface area of the catalyst is sufficiently wide, the reactants are easily diffused, and the desulfurization reaction can proceed with high efficiency.

Further, in order to increase the effective number of pores satisfying the above pore conditions, the pore size distribution of the catalyst, that is, the proportion of pores having an average pore size of about ± 15 mm is at least the total pore volume. 75%, preferably about 80% or more.
Moreover, the pore distribution is preferably monomodal. A catalyst having a sharper pore size distribution has fewer pores that are not involved in the activity, and a higher desulfurization activity can be obtained.

  The catalyst shape of the catalyst according to the present invention is not particularly limited, and various shapes usually used for this type of catalyst, for example, a cylindrical shape, a trilobal type, a four-leaf type, and the like can be adopted. In general, the size of the catalyst according to the present invention is preferably about 1 to 2 mm in diameter and about 2 to 5 mm in length.

  The mechanical strength of the catalyst according to the present invention is preferably about 2 lbs / mm or more in terms of side crush strength (SCS). If the SCS is smaller than this, the catalyst charged in the reactor may be crushed and a differential pressure may be generated in the reactor, making it impossible to continue the hydrotreating operation. The close-packed bulk density (CBD) of the catalyst according to the present invention is preferably about 0.6 to 1.2.

<Hydroprocessing method using hydrodesulfurization catalyst>
The catalyst according to the present invention can be used for hydrotreating hydrocarbon oils, as with other desulfurization catalysts. The catalyst according to the present invention has a very high desulfurization activity, and the hydrocarbon oil can be used not only when the reaction conditions are substantially the same as those in the conventional hydrotreatment, but also when the reaction conditions are milder. In particular, the sulfur content in the gas oil fraction can be greatly reduced.

For example, a hydrocarbon oil (for example, a light oil fraction) containing the catalyst according to the present invention and a sulfur compound under conditions of a hydrogen partial pressure of about 3 to 8 MPa, about 300 to 420 ° C., and a liquid space velocity of about 0.3 to 5 h ^−1. Etc.) can be reduced to reduce sulfur compounds containing hardly desulfurizable sulfur compounds in hydrocarbon oils.

  The sulfur content of the product oil obtained by hydrotreating using the catalyst according to the present invention is 500 ppm or less, more specifically about 20 to 300 ppm. By using the catalyst according to the present invention, although it depends on the properties of the raw material oil, it is possible to obtain a product oil having a sulfur content similar to the conventional one over a long period of time under milder hydrotreating conditions.

  The target oil (raw oil) to be hydrotreated by the catalyst according to the present invention may be any oil containing hydrocarbons, such as straight-run kerosene, straight-run light oil, catalytic cracking light oil, pyrolysis light oil, hydrogenation. Kerosene and light oil fractions such as treated light oil, desulfurized light oil, and vacuum distilled light oil (VGO) are suitable. Typical examples of properties of these feedstock oils include those having a boiling range of 150 to 450 ° C. and a sulfur content of 5% by mass or less.

  In order to perform the hydrotreating method using the catalyst according to the present invention on a commercial scale, a fixed bed, moving bed, or fluidized bed type catalyst layer of the catalyst according to the present invention is formed in the reactor, and this reactor is used. The feed oil may be introduced into the interior and the hydrogenation reaction may be performed under the above conditions. Most commonly, a fixed bed catalyst layer is formed in the reactor, feedstock is introduced into the top of the reactor, passed through the fixed bed from top to bottom, and product flows out from the bottom of the reactor. On the contrary, the raw material oil is introduced into the lower part of the reactor, passed through the fixed bed from the bottom up, and the product flows out from the upper part of the reactor.

  The hydrotreating method may be a one-stage hydrotreating method performed by filling the catalyst according to the present invention into a single reactor, or a multistage continuous hydrotreating performed by filling several reactors. It may be a method.

  Note that the catalyst according to the present invention is activated by sulfiding in a reaction apparatus before use (that is, prior to performing the hydrotreating method). This sulfidation treatment is conducted at about 200 to 400 ° C., preferably about 250 to 350 ° C. under a hydrogen atmosphere at normal pressure or higher, and a petroleum distillate containing sulfur compounds, dimethyl disulfide or disulfide. It is performed using a material added with a sulfurizing agent such as carbon or hydrogen sulfide.

Next, embodiments and effects of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.
First, analysis methods of physical properties and chemical compositions of catalysts in Examples and Comparative Examples are shown below.

<Specific surface area>
The specific surface area was measured by the BET method using nitrogen adsorption. The nitrogen adsorption device used was a surface area measuring device (Bell Soap 28) manufactured by Bell Japan.

<Pore volume, average pore diameter, and pore distribution>
(Used equipment)
The pore volume, average pore diameter, and pore distribution were measured by mercury porosimetry. As the mercury intrusion apparatus, a porosimeter (MICROMERITICS AUTO-PORE 9200: manufactured by Shimadzu Corporation) was used.

(Measurement principle)
The mercury intrusion method is based on the law of capillary action. In the case of mercury and cylindrical pores, this law is expressed by the following formula (E). In formula (E), D is the pore diameter, P is the applied pressure, γ is the surface tension, and θ is the contact angle. The mercury volume entering the pores as a function of the applied pressure P was measured. The surface tension of the pore mercury of the catalyst was 484 dyne / cm, and the contact angle was 130 degrees.
Formula (E): D = − (1 / P) ⁴ γ cos θ

The pore volume is the total volume of mercury per gram of catalyst that has entered the pores. The average pore diameter is the average value of D calculated as a function of P.
The pore distribution is a distribution of D calculated as a function of P.

(Measurement procedure)
(1) The vacuum heating deaerator was turned on, and it was confirmed that the temperature was 400 ° C. and the degree of vacuum was 5 × 10 −2 Torr or less.
(2) The sample burette was placed in a vacuum heating and degassing device while being empty.
(3) When the degree of vacuum was 5 × 10 ⁻² Torr or less, the sample burette was removed from the vacuum heating and degassing device with the cock closed, and after cooling, the weight was measured.
(4) A sample (catalyst) was placed in a sample bullet.
(5) The sample burette containing the sample was put on a vacuum heating and degassing apparatus, and held for 1 hour or more after the degree of vacuum became 5 × 10 ⁻² Torr or less.
(6) The sample burette containing the sample was removed from the vacuum heating and degassing device, and after cooling, the weight was measured to obtain the sample weight.
(7) The sample was put into the cell for AUTO-PORE 9200.
(8) Measured by AUTO-PORE 9200.

<Analysis of chemical composition>
(Devices used and analysis methods)
The metal analysis in the catalyst was performed using inductively coupled plasma emission analysis (ICPS-2000: manufactured by Shimadzu Corporation).
The metal was quantified by an absolute calibration curve method.

(Measurement procedure)
(1) 0.05 g of catalyst, 1 ml of hydrochloric acid (50% by volume), one drop of hydrofluoric acid, and 1 cc of pure water were added to Uniseal, and dissolved by heating.
(2) After dissolution, the sample was transferred to a polypropylene volumetric flask (50 ml), pure water was added and weighed to 50 ml.
(3) This solution was measured by ICPS-2000.

[Production Example 1] Preparation of zeolite Zeolite 1 used in the following examples and the like was prepared by the following method.
29 g of sodium aluminate containing 17.0% by mass of Na ₂ O and 22.0% by mass of Al ₂ O ₃ was added to 230 g of an aqueous solution of 21.7% by mass of sodium hydroxide in an autoclave container while stirring. It was. While stirring the solution after addition of sodium aluminate, it was added to 232 g of No. 3 water glass having a SiO ₂ concentration of 24% by mass, sufficiently stirred, and then heated and aged at 95 ° C. for 12 hours. After completion of ripening, the reaction product was cooled to a temperature of 70 ° C. or lower, and then the synthesized product was taken out, filtered, washed and dried to prepare a Na—Y type seed crystal. The composition of the obtained seed composition was an oxide molar ratio of Na ₂ O / Al ₂ O ₃ = 16, SiO ₂ / Al ₂ O ₃ = 15, and H ₂ O / Al ₂ O ₃ = 330. .

Subsequently, 220 g of a sodium silicate solution having a SiO ₂ concentration of 29% by mass in an autoclave container was added to 31.7 g of sodium aluminate containing 33.0% by mass of Na ₂ O and 36.5% by mass of Al ₂ O _3. Then, 6 g of sodium hydroxide and 747.0 g of pure water were added and stirred sufficiently, then 8.0 g (dry basis) of the seed crystal was added, stirred again and heated at 95 ° C. for 12 hours. Aged. After completion of the aging, the mixture was cooled to a temperature of 70 ° C. or lower, and then the synthesized product was taken out, filtered, washed and dried to obtain a Na—Y zeolite 1. Thereafter, the Na-Y zeolite 1 was put in a 5 mass% ammonium nitrate aqueous solution, stirred for 20 minutes under a constant condition at 60 ° C, filtered, and subjected to ion exchange treatment. After the ion exchange treatment was repeated twice, NH3 type Y zeolite 1 was obtained by drying at 120 ° C. for 12 hours.
Thereafter, the obtained NH 3 type Y zeolite 1 was calcined at 600 ° C. for 4 hours under air flow to obtain H type Y zeolite 1 (hereinafter simply referred to as “zeolite 1”). The composition of the prepared reaction mixture (zeolite 1) thus obtained was an oxide molar ratio of Na ₂ O / Al ₂ O ₃ = 2.80 and SiO ₂ / Al ₂ O ₃ = 8.50. . Moreover, the amount of the aforementioned seed Al ₂ O ₃ with respect to the total Al ₂ O ₃ in the reaction mixture was 0.098 mol%.

Zeolite 2 to zeolite 5 were also prepared according to the method of zeolite 1 described above.
SiO ₂ / Al ₂ O ₃ (molar ratio) of zeolite 1 to zeolite 5, crystal lattice constant, molar ratio of Al in zeolite framework to total Al ([Al in zeolite framework] / [total Al]), and crystallite diameter Is shown in Table 1.
_{Here, SiO 2 / Al 2 O 3} ( molar ratio) was measured from the chemical composition analysis by ICP analysis. The crystal lattice constant was measured using an X-ray analyzer (XRD) according to ASTM D3906. The molar ratio of Al in the zeolite framework to all Al atoms was calculated from the chemical composition analysis value and the XRD measurement value. Details were as described above.

[Example 1]
2.0 g of zeolite 1 and 109.4 g of alumina hydrate are kneaded, extruded and then calcined at 600 ° C. for 2 hours to form a zeolite-alumina composite carrier (zeolite) having a columnar shaped product having a diameter of 1/16 inch. / Alumina mass ratio = 7/93, pore volume = 0.63 ml / g, specific surface area = 336 m ² / g, average pore diameter = 69 mm).
Separately, an impregnation solution was prepared by dissolving 5.51 g of cobalt carbonate, 19.02 g of molybdophosphoric acid and 2.46 g of orthophosphoric acid (85% aqueous solution) in 40.0 g of ion-exchanged water.
In an eggplant-shaped flask, 50.0 g of the above zeolite-alumina composite carrier was added, and the whole amount of the above impregnation solution was added thereto with a pipette and immersed at about 25 ° C. for 1 hour. Then, it air-dried in nitrogen stream, dried at 120 degreeC in the muffle furnace for about 1 hour, and baked at 500 degreeC for 4 hours, and the catalyst A was obtained.
Catalyst A had a specific surface area of 227 m ² / g, a pore volume of 0.40 ml / g, and an average pore size of 80 mm.

[Example 2]
2.0 g of zeolite 2 and 109.4 g of alumina hydrate are kneaded, extruded, and calcined at 600 ° C. for 2 hours to form a zeolite-alumina composite carrier (zeolite) of a columnar molded product having a diameter of 1/16 inch. / Alumina mass ratio = 7/93, pore volume = 0.61 ml / g, specific surface area = 342 m ² / g, average pore diameter = 68 mm).
Separately, an impregnation solution was prepared by dissolving 5.51 g of cobalt carbonate, 19.02 g of molybdophosphoric acid and 2.46 g of orthophosphoric acid (85% aqueous solution) in 40.0 g of ion-exchanged water.
In an eggplant-shaped flask, 50.0 g of the above zeolite-alumina composite carrier was added, and the whole amount of the above impregnation solution was added thereto with a pipette and immersed at about 25 ° C. for 1 hour. Then, it air-dried in nitrogen stream, dried at 120 degreeC in the muffle furnace for about 1 hour, and baked at 500 degreeC for 4 hours, and obtained the catalyst B.
Catalyst B had a specific surface area of 223 m ² / g, a pore volume of 0.43 ml / g, and an average pore size of 81 kg.

[Example 3]
2.0 g of zeolite 3 and 109.4 g of alumina hydrate are kneaded, extruded and then calcined at 600 ° C. for 2 hours to form a zeolite-alumina composite carrier (zeolite) of a columnar molded product having a diameter of 1/16 inch. / Alumina mass ratio = 7/93, pore volume = 0.63 ml / g, specific surface area = 333 m ² / g, average pore diameter = 69 mm).
Separately, an impregnation solution was prepared by dissolving 5.51 g of cobalt carbonate, 19.02 g of molybdophosphoric acid and 2.46 g of orthophosphoric acid (85% aqueous solution) in 40.0 g of ion-exchanged water.
In an eggplant-shaped flask, 50.0 g of the above zeolite-alumina composite carrier was added, and the whole amount of the above impregnation solution was added thereto with a pipette and immersed at about 25 ° C. for 1 hour. Then, it air-dried in nitrogen stream, it was made to dry at 120 degreeC in a muffle furnace for about 1 hour, and it baked at 500 degreeC for 4 hours, and the catalyst C was obtained.
Catalyst C had a specific surface area of 220 m ² / g, a pore volume of 0.38 ml / g, and an average pore size of 83 mm.

[Example 4]
2.0 g of zeolite 4 and 109.4 g of alumina hydrate are kneaded, extruded and then calcined at 600 ° C. for 2 hours to form a zeolite-alumina composite carrier (zeolite composite) having a columnar shaped product having a diameter of 1/16 inch. / Alumina mass ratio = 7/93, pore volume = 0.64 ml / g, specific surface area = 330 m ² / g, average pore diameter = 70 Å.
Separately, an impregnation solution was prepared by dissolving 5.51 g of cobalt carbonate, 19.02 g of molybdophosphoric acid and 2.46 g of orthophosphoric acid (85% aqueous solution) in 40.0 g of ion-exchanged water.
In an eggplant-shaped flask, 50.0 g of the above zeolite-alumina composite carrier was added, and the whole amount of the above impregnation solution was added thereto with a pipette and immersed at about 25 ° C. for 1 hour. Then, it air-dried in nitrogen stream, dried at 120 degreeC in the muffle furnace for about 1 hour, and baked at 500 degreeC for 4 hours, and the catalyst D was obtained.
Catalyst D had a specific surface area of 224 m ² / g, a pore volume of 0.39 ml / g, and an average pore size of 81 kg.

[Comparative Example 1]
A zeolite-alumina composite carrier having the same shape as in Example 1 (zeolite / alumina mass ratio = 7/93, pore volume = 0) in the same manner as in Example 1 except that zeolite 1 in Example 1 was replaced with zeolite 5. 0.63 ml / g, specific surface area = 334 m ² / g, average pore diameter = 71 Å). 50.0 g of this zeolite-alumina composite carrier was put into an eggplant-shaped flask, and the same amount of the same impregnation solution as in Example 1 was added and immersed in the same manner as in Example 1, and then air-dried in the same manner as in Example 1. Then, drying and calcination were performed to obtain catalyst a.
Catalyst a had a specific surface area of 223 m ² / g, a pore volume of 0.37 ml / g, and an average pore size of 82 mm.

Table 2 shows the elemental analysis values of Catalysts A to D and Catalyst a, and Table 3 shows the catalytic properties. In Table 3, “SA” is specific surface area (m ² / g), “PV” is pore volume (ml / g), “MPD” is average pore diameter (細孔), and “PSD” is fine. The pore distribution (what percentage of the pore volume is contained in MPD ± 15%) (%), and “CBD” means the closest packed bulk density (g / ml). As shown in Tables 2 and 3, the catalysts A to D and the catalyst a were almost the same in chemical composition and physical shape.

[Hydrolysis reaction of straight-run gas oil 1]
Using the catalysts A to D and the catalyst a prepared in Examples 1 to 4 and Comparative Example 1, hydrogenation treatment of straight-run gas oil having the following properties was performed in the following manner.
First, the catalyst was filled into a high-pressure flow reactor to form a fixed bed catalyst layer, and pretreated under the following conditions.
Next, a mixed fluid of the raw material oil heated to the reaction temperature and the hydrogen-containing gas is introduced from the upper part of the reactor, and the hydrogenation reaction proceeds under the following conditions, and the mixed fluid of the product oil and the gas is reacted. The oil was discharged from the lower part of the apparatus, and the produced oil was separated by a gas-liquid separator.

Catalyst pretreatment conditions:
Pressure: normal pressure,
Atmosphere: Hydrogen sulfide (5%) / under hydrogen gas flow
Temperature: Step temperature rise: maintained at 150 ° C. for 0.5 hour and then maintained at 350 ° C. for 1 hour.

Hydrogenation reaction conditions:
Reaction temperature: 360 ° C., and a temperature at which the product oil sulfur content becomes 200 ppm,
Pressure (hydrogen partial pressure); 5 MPa,
Liquid space velocity; 1.2 h ⁻¹ ,
Hydrogen / oil ratio; 250 m ³ / m ³ .

Raw oil properties:
Oil type: Middle East straight gas oil,
Specific gravity (15/4 ° C.); 0.8648,
Distillation properties: initial boiling point 206.0 ° C, 50% point 319.0 ° C, 90% point 372.0 ° C, end point 390.0 ° C,
Sulfur component: 1.44% by mass,
Nitrogen component: 1700 ppm,
Kinematic viscosity (@ 30 ° C.); 6.660 cSt,
Pour point: 2.5 ° C
Cloudy point; 3.0 ° C,
Cetane index; 53.2,
Saybolt color; -16,
ASTM color: L1.0,
Aniline point: 74.2 ° C.

The reaction results were analyzed by the following method.
The reaction apparatus was operated at 360 ° C., and when 6 days passed, the product oil was collected and analyzed for its properties. Thereafter, each catalyst was operated for 200 days at a temperature at which the product oil sulfur content was 200 ppm. During this constant operation of the generated oil sulfur content, the operation was performed while compensating for the operating temperature in order to suppress an increase in the generated oil sulfur content due to catalyst deterioration.

[1] Desulfurization rate (HDS) (%):
By converting the sulfur content in the raw material into hydrogen sulfide by a desulfurization reaction, the ratio of the sulfur content that disappeared from the raw material oil was defined as the desulfurization rate, and was calculated from the sulfur analysis values of the raw material oil and the product oil by the following formula.
[2] Desulfurization reaction rate constant (Ks):
The constant of the reaction rate equation for obtaining the reaction order of 1.5 with respect to the reduction amount of the sulfur content (Sp) of the product oil was defined as the desulfurization reaction rate constant (Ks). The higher the reaction rate constant, the better the catalytic activity. These results are shown in Table 4.

Desulfurization rate (%) = [(Sf−Sp) / Sf] × 100
Desulfurization reaction rate constant = 2 × [1 / √ (Sp) −1 / √ (Sf)] × (LHSV)
In the above formula, Sf: Sulfur content (mass%) in the raw material oil,
Sp: Sulfur content (mass%) in the reaction product oil,
LHSV: Liquid space velocity (h ⁻¹ ).

Specific activity (%) = [each desulfurization reaction rate constant] / [desulfurization reaction rate constant of comparative catalyst a] × 100

[3] A graph plotting the desulfurization reaction rate constant (Ks) calculated in [2] against the crystallite diameter of zeolite is shown in FIG.
[4] Desulfurization reaction rate constant (Ks):
The constant of the reaction rate equation for obtaining the reaction order of 1.5 with respect to the reduction amount of the sulfur content (Sp) of the product oil was defined as the desulfurization reaction rate constant (Ks). The higher the reaction rate constant, the better the catalytic activity. Table 4 shows the results when the reaction was conducted at 360 ° C.

As shown in Table 4, the catalysts A to D of Examples 1 to 4 have a higher desulfurization rate, a larger desulfurization reaction rate constant, and a very high specific activity of 130% or more than the catalyst a of Comparative Example 1. It was. In particular, when the catalyst a is used, the sulfur content of the produced oil is about 0.05% by mass, whereas when the catalysts A to D are used, the sulfur content is 0.03% by mass or less. Sulfur content could be reduced.
Further, as shown in FIG. 1, the crystallite diameter of zeolite contained in the catalyst affects the desulfurization reaction rate constant of the catalyst, and the desulfurization reaction rate constant peaks at a crystallite diameter of about 85 to 95 nm. It was found that when the crystallite diameter is 100 nm or more, the value tends to decrease rapidly.

  Further, Table 5 shows operating temperatures after 100 days and 200 days. When the catalysts A to D of Examples 1 to 4 were used, the difference between the operating temperature on the 100th day and the operating temperature on the 200th day was 1 to 4 ° C., and the generated oil sulfur content was operated for a long time. Even in that case, the operating temperature did not have to be increased as much. On the other hand, when the catalyst a of Comparative Example 1 was used, on the 200th day, it was necessary to increase it by 10 ° C. or more from the operating temperature on the 100th day. From these results, it is clear that the catalyst according to the present invention can maintain stable activity over a long period of time.

  As is clear from the above results, the catalyst according to the present invention is suitable for desulfurization reaction of hydrocarbon oil such as light oil under the conditions of hydrogen partial pressure and reaction temperature which are almost the same as those in the conventional light oil hydrotreatment. And has extremely excellent activity. For this reason, the catalyst which concerns on this invention can supply easily the light oil base material with very little sulfur content, for example, the light oil base material whose sulfur content is still lower than 0.05 mass%.

Claims (1)

A catalyst in which cobalt, molybdenum, and phosphorus are supported on a composite oxide support containing 80 to 99% by mass of alumina and 1 to 20% by mass of HY zeolite,
On a catalyst basis, in terms of oxide, containing 3-6 wt% cobalt, 16-24 wt% molybdenum, and 0.8-4.5 wt% phosphorus,
Specific surface area measured by nitrogen adsorption method is 210 to 280 m ² / g,
Pore volume measured by mercury intrusion method is 0.3 to 0.6 ml / g
The average pore diameter in the pore distribution measured by mercury porosimetry is 75 to 95 mm, and the pore volume in the range of average pore diameter ± 15 mm is at least 75% of the total pore volume;
The HY zeolite is
_{(A) SiO 2 / Al 2} O 3 ( molar ratio), 3-10,
(B) the crystal lattice constant is 2.435 to 2.465 nm,
(C) The molar ratio of Al in the zeolite framework to the total Al is 0.4 to 1, and (d) the crystallite diameter is 30 to 100 nm,
A hydrodesulfurization catalyst for hydrocarbon oil.

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