JPH083568A - Mild hydrocracking of heavy hydrocarbon feedstock using silica/alumina catalyst - Google Patents

Abstract

PURPOSE: To mildly hydrocrack a heavy oil in excellent conversion by using a catalyst containing a silica-alumina carrier, molybdenum oxide, nickel oxide, etc., and having a specified pore size distribution and a specified molybdenum gradient.

CONSTITUTION: A heavy hydrocarbon feedstock is mildly hydrocracked by using as the catalyst a particulate catalyst supported by porous alumina containing 4.0-25.0 wt.%, based on the weight of the support, silica, having a molybdenum gradient(MbG) as defined by the equation of 1-10, comprising 2.0-6.0 wt.% group VIII metal oxide, 12.0-25.0 wt.% molybdenum oxide, and 0-3.0 wt.% phosphorus oxide, having a total surface area of 150-250 m²/g, a pore diameter distribution in which the pores with diameters of below 10 nm account for 20.0-40.0% of the total pore volume, the pores with diameters of 10-16 nm account for 28.4-34.1% of the total pore volume, the pores with diameters of above 16 nm account for 30.0-50.0% of the total pore volume, and the macropores with diameters above 25 nm account for 25.0-40.0% of the total pore volume, and having a total pore volume of 0.75-0.92 cm³/g.

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

This invention relates to a process for the mild hydrocracking of heavy oils. More specifically, the present invention provides
Vacuum gas oil (VGO) and a high proportion of vacuum distillation bottom oil (V
It relates to a catalytic process for converting heavy oils boiling above 345 ° C, such as VGO containing R), to light distillation products boiling below 345 ° C.

In the mild hydrocracking process of the present invention,
Hydrocarbon feedstocks containing sulfur and metals, such as residual oil-containing heavy oils, are treated at high temperature with hydrogen and a certain amount of nickel or cobalt oxides supported on a porous silica-containing alumina support. Contacting with a catalyst composition comprising a particular Group VIII metal, a specified amount of molybdenum oxide, and optionally a specified amount of a phosphorus oxide such as phosphorus pentoxide.
In the mild catalytic hydrocracking process of the present invention, the hydrocarbon feedstock is hydrogen and a catalyst having a particular pore size distribution and molybdenum distribution and hydrocarbons boiling above 540 ° C. of the prior art. Hydroproces
sing) Contact is made in such a way that the conversion is considerably higher than that obtained by the catalyst, while at the same time avoiding the formation of a high degree of precipitate.

[0003]

2. Description of the Related Art U.S. Pat. No. 4,941,964 is
It discloses a method for hydrotreating a hydrocarbon feed containing sulfur and metals in such a way that the catalyst is kept isothermally and fed in uniform quality. The catalyst has a total surface area of 150-210 m ² / g and 10-16
4. Micropores with a diameter of nm (100-160Å) make up 70-85% of the total pore volume of the catalyst, and macropores with a diameter greater than 25 nm are 5. of the total pore volume of the catalyst.
With a pore size distribution that constitutes 5 to 22.0%, 0.5
3.0-5.0% by weight of Group VIII metal oxides on a porous alumina support having a total pore volume (TPV) of 0-0.75 cm ³ / g, of Group VIB metals. Oxide 0-2
It contains 4.0% by weight and 14.5 to 2.0% by weight of phosphorus oxide.

US Pat. No. 4,670,132 discloses catalyst compositions useful in the hydroconversion of heavy oils.
The catalyst composition comprises a high iron content bauxite with one or more of the following promoters added, the promoter being phosphorus, molybdenum, cobalt, nickel or tungsten. The bauxite catalyst typically contains 25 to 35 wt% aluminum. The catalyst contains elements (including aluminum and molybdenum, if present) when examined on the outer surface of the pellet in the fresh oxide state using X-ray photoelectron spectroscopy (XPS).
Has certain characteristics. For these catalysts containing molybdenum, Mo on the outer surface of the pellet
The / Al atomic ratio is in the range of 0.03 to 0.09.

US Pat. No. 4,652,545 discloses catalyst compositions useful in the hydroconversion of heavy oils.
The catalyst composition contains a porous alumina support, such as a small amount of silica, nickel or cobalt in an acid extractable form, and (i) at least 70% TPV.
% Are pores having a diameter of 8 to 12 nm (80 to 120Å), and (ii) less than 0.03 cm ³ / g (6% of TPV) are pores having a diameter of less than 8 nm (80 Å), (iii)
0.05-0.1 cm ³ / g (3-20% of TPV) is 12
0.5 to 5% nickel or cobalt on a carrier having a TPV of 0.15 to 1.5 cm ³ / g with a pore size distribution such that the diameter is more than nm (120 Å).
And molybdenum of 1.8 to 18% (all calculated as oxides). US Pat. No. 4,652,545
Although the specification teaches that the inclusion of nickel or cobalt contained in acid-extractable form in the catalyst is advantageous in terms of hydroconversion of heavy oils, it does not It does not suggest that gradient catalysts favor heavy oil hydroconversion.

US Pat. No. 4,588,709 describes
Group VIB element (eg molybdenum) 5 to 30% by weight
Containing 1 to 5% by weight of a Group VIII element (eg nickel),
Disclosed are catalyst compositions useful in the hydroconversion of heavy oils. The completed catalyst is 15 ~ 30nm (150 ~ 300nm
Å) has an average pore size of Å), and when the outer surface of the pellet was inspected in the sulfide state using X-ray photoelectron spectroscopy (XPS), certain characteristics of the active components (molybdenum and nickel) have.

US Pat. No. 4,579,649 describes the hydrogenation of heavy oils containing Group VIB elements (eg molybdenum), Group VIII elements (eg nickel) and phosphorus oxides on a porous alumina support. Disclosed are catalyst compositions useful for conversion. The catalyst has certain characteristics for the three active components (molybdenum, nickel and phosphorus) when examined on the outer surface of the pellet in the sulfided state using X-ray photoelectron spectroscopy (XPS). ing.

US Pat. No. 4,520,128 describes a Group VIB element (eg molybdenum) 5 to 30% by weight and a Group VIII element (eg nickel) 0.1 to 8.0% by weight on a porous alumina support. And relatively high (5-30
Disclosed are catalyst compositions useful in the hydroconversion of heavy oils containing (wt%) concentrations of phosphorus oxides. The finished catalyst has an average pore size of 14.5-15.4 nm (145-154Å). Here again, when the outer surface of the pellets is inspected in the sulfide state using X-ray photoelectron spectroscopy (XPS), it has certain characteristics regarding the three active elements (molybdenum, nickel and phosphorus). ing.

US Pat. No. 5,047,142 discloses a process for hydrotreating a hydrocarbon feed containing sulfur and metals with a feed of uniform quality under isothermal conditions. The catalyst has a molybdenum gradient of 6.
1.0-5.0 wt% oxide of nickel or cobalt on a porous alumina support with 15-30% nickel or cobalt in acid-extractable form, such as having a value less than 0. , And molybdenum oxide 10.
0 to 25.0% by weight of the composition. The catalyst also has a total surface area of 150-210 m ² / g, 0.50-0.7.
With respect to the total pore volume of 5 cm ³ / g as well as the total pore volume of the above catalyst, pores having a diameter of less than 10 nm (100 Å) make up less than 25.0%, and have a diameter of 10 to 16 nm (100 to 1 nm).
The pore size distribution is such that pores having a diameter of 60Å) constitute 70.0 to 85.0%, and pores having a diameter exceeding 25 nm (250Å) constitute 10 to 15.0%.

US Pat. No. 4,886,582 describes a Group VIB such as molybdenum on a porous refractory oxide such as lithia-alumina or silica-alumina, US Pat.
Or containing at least one metal hydrogenation component, including Group VIII, such as nickel, less than 15 wt% of the metal hydrogenation component, calculated as trioxide, and at least 75% of the total pore volume. , 2 nm from the pore mode diameter (20
Å) Smaller to 2 nm (20 Å) than the pore mode diameter
Pores up to a large diameter, less than 10% of the total pore volume are pores with a diameter of less than 6 nm (60Å), and 3 to 10% of the total pore volume have a diameter of more than 11 nm (110Å). It is a pore and has a pore size distribution such that the pore mode diameter is 7 to 9 nm (70 to 90Å).

US Pat. No. 4,846,961 discloses the use of a porous refractory oxide such as silica-alumina on
Nickel discloses phosphorus, and the hydrotreating catalyst containing molybdenum 19 to 21.5 wt% (as MoO _3). The catalyst has a narrow pore size distribution, at least 75% of the pore volume is 5-11 nm (50-110Å) in diameter and at least 10% of the pore volume is 7 nm.
The pores have a diameter of less than (70Å), and at least 60% of the pore volume has a diameter within 2 nm (20Å) above and below the average pore diameter. The catalyst is used for hydrotreating hydrocarbon oils, especially those containing sulfur and nitrogen.

US Pat. No. 4,686,030 discloses a catalyst containing at least one active metal hydride component supported on an amorphous, porous refractory oxide such as silica-alumina. A mild hydrocracking method for use is disclosed. The catalyst has a narrow pore size distribution with at least 75% of the total pore volume in pores with a diameter of 5 to 13 nm (50 to 130Å). Preferably, at least 60% of the pore volume is 2 nm above and below the pore mode diameter (20 Å)
Within the pores in the range of 5.5 to 10 nm (55 to 100 Å). In one embodiment, a reduced pressure hydrocarbon gas oil is a hydrocarbon fraction boiling at a temperature above or below 371 ° C. (700 ° F.) from a fraction of the gas oil that boils above 371 ° C. (700 ° F.). Contacted under mild hydrocracking conditions, correlated to convert to product,
With the simultaneous desulfurization and denitrification, it is slowly hydrocracked. In other embodiments, the hydrocarbon oil may be desulfurized or denitrified before or after the mild hydrocracking.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the problems of the prior art described above to provide a heavy hydrocarbon feedstock with excellent conversion while maintaining low levels of precipitate formation. And mild hydrocracking to obtain useful hydrocarbon products with lower boiling range.

[0014]

SUMMARY OF THE INVENTION The present invention is directed to a hydrocarbon feedstock, such as distillation bottoms or vacuum gas oil, which is contacted with hydrogen and a catalyst at elevated temperatures and pressures below 10.5 MPa (1,500 psig). A process for the mild hydrocracking of hydrocarbon feedstocks containing sulfur and metals with a significant proportion of components boiling below 540 ° C (1,000 ° F).

According to the invention, the catalyst is an oxide of a Group VIII metal, preferably nickel or cobalt, 2.0.
-6.0 wt%, preferably 2.5-3.5 wt%; molybdenum oxide 12.0-25.0 wt%, preferably 1
2.0 to 18.0% by weight; and phosphorus oxides, preferably 0 to 3.0% by weight of P ₂ O ₅ , preferably 0 to 2.0% by weight, all based on the weight of the carrier. .0-2
It is supported on a porous silica-alumina carrier containing 5.0% by weight, preferably 10.0-25.0% by weight of silica. The molybdenum gradient (MbG) of the catalyst is 1-1.
It is 0, preferably 1 to 6, and MbG is defined by the following ratio.

[0016]

[Equation 2]

The catalyst then comprises a total surface area of 150 to 250 m ² / g; and 20.0 to 40.0% of pores with a diameter of less than 10 nm, based on the total pore volume, 1
28.4 to 34.1% of pores having a diameter of 0 to 16 nm
And pores having a diameter of more than 16 nm are 30.0
With a pore size distribution such that macropores having a diameter of more than 25 nm make up 25.0 to 40.0% and a total of 0.75 to 0.92 cm ³ / g. Pore volume.

The catalyst used according to the invention is 0.7
Total pore volume of 5 to 0.92 cm ³ / g and 150 to 250 m ²
It has a surface area of / g. The pore volume distribution measured by a mercury porosimeter is 25-40% of the pore volume at 25 nm (25
It has macropores with a diameter exceeding 0Å) and has a pore volume of 3
0 to 50% in pores with a diameter exceeding 16 nm (160 Å), and 28.4 to 34.1% of the pore volume is 10 to 16 nm
It has pores with a diameter of (100 to 160Å), and has 20 to 40% of the pore volume in pores with a diameter of less than 10 nm (100Å). The pore mode of the catalyst measured by the BET method is 8
It is in the range of up to 12 nm (80 to 120 Å). A preferred pore volume distribution measured by mercury porosimetry has 28-35% of the pore volume in macropores with a diameter greater than 25 nm (250 Å) and 35-45% of the pore volume in the range of 10- 10. 16
It has pores with a diameter of nm (100-160Å), and has 24-32% of the pore volume in pores with a diameter of less than 10 nm (100Å). The pore mode of the catalyst measured by the BET method is 8 to 12 nm (80 to 120Å).

The use of the catalysts defined above not only provides the benefits of hydrocarbon conversion, but also the formation of precipitates at a level similar to that of conventional bimodal alumina-based catalysts. To maintain. The present invention is a significant improvement over prior art catalysts with respect to precipitate formation and reactor runnability.

The operating conditions of the process of the present invention are such that hydrocarbon feedstocks boiling above 345 ° C. are converted to hydrocarbon products boiling at lower temperatures at conversions of 10-60% by volume. It is a condition.

The bottoms feedstock can be contacted with hydrogen and catalyst using a wide variety of reactor types.
The preferred means of achieving such contact is a fixed bed hydrotreating unit, a single continuous stirred tank reactor or a single boiling bed reactor, or two to five series of continuous stirred tank reactions or boiling. Including bed reactors, ebullated bed reactors are especially preferred. The process of the present invention achieves a higher conversion of fractions boiling above 540 ° C. to fractions boiling at lower temperatures compared to conventional bimodal alumina-based catalysts. Moreover, it is particularly effective in maintaining the conversion of distillates boiling above 345 ° C, the formation of precipitates, and the HDS capacity.

The diminishing demand for heavy fuel oil is causing oil refiners to explore ways to convert heavier hydrocarbon feedstocks to more valuable light products. Petroleum refiners have several choices for increasing middle distillate products. They include hydrocracking, fluid catalytic cracking and coking processes, all of which require large equipment in the refinery. Due to these high costs, oil refiners are continually exploring conversion methods that can be implemented on existing equipment units. An additional option is to employ a mild hydrocracking (MHC) process, which is an evolution of the VGO hydrodesulfurization (HDS) process. The main feedstock for this MHC method is vacuum gas oil (VG
O), but other types of gas oils such as coking gas oil and deasphalted oil can also be used.

A major advantage of MHC is that it can be implemented within the operational constraints of existing VGO hydrotreating equipment. M
Typical conditions of the HC method are as follows. Temperature: 382-416 ° C (720-780 ° F), Hydrogen Pressure: 4.2-8.4MPa (600-1,200psi)
g), H ₂ / oil ratio: 168.5-337 Nm ³ / m ³ (1,000
0-2,000 SCF / BBL), space velocity: 0.4-1.5 v / v / h. Conversely, a true high conversion hydrocracking unit operates as follows. Temperature: 371-482 ° C (700-900 ° F), Hydrogen pressure: 12.5-20.8MPa (1,800-3,0)
00 psig), H ₂ / oil ratio: 235.9 to 1,011 Nm ³ / m ³ (1,
400-6,000 SCF / BBL), space velocity: 0.3-1.5 v / v / h. The main difference between the two methods is hydrogen pressure.

The products obtained by the MHC process are low-sulfur heavy oil (60-80%) and middle distillates (20-40%). This hydrotreated heavy oil is also a feedstock excellent in catalytic cracking due to its high hydrogen content and low nitrogen content compared to the feedstock feed. The quality of MHC produced diesel fractions is usually close to the cetane index diesel oil specification and therefore can be added to a diesel oil storage tank.

Switching from HDS mode to MHC mode can be accomplished in a variety of ways, and it is presumed that a refinery will be installed to recover excess middle distillate.
One way to increase the production of middle distillates from a unit packed with HDS catalyst is to raise the operating temperature.
The MHC method is typically carried out using a general hydrotreating catalyst.
10-30% by volume of hydrocarbon feedstock boiling above 343 ° C (650 ° F) at 343 ° C (650 ° F)
Or convert to a middle distillate that boils at temperatures below.

Another way to increase the middle distillate product is to replace the HDS catalyst on a non-acidic alumina support, at least in part, with a slightly acidic catalyst. Higher activity catalysts are still in search. The higher the activity of the catalyst, the lower the temperature required to obtain the product for a given sulfur, nitrogen and metal content, in any given boiling range. VG containing a high proportion of residual oil
For O, HDS catalysts usually give a fraction boiling less than 10% by volume above 345 ° C. 540 ° C. with a known hydrotreating catalyst based on alumina
Of residual oil components boiling above (1,000 ° F),
Conversion to products boiling at temperatures of 540 ° C. (1,000 ° F.) or lower is accomplished primarily by pyrolysis reactions.

A particularly difficult problem that occurs with resid hydrotreating units using recently known catalysts is that at high (> 50% by volume) conversion, insoluble carbonaceous materials (also called precipitates). Is to form. Large amounts of precipitate can cause blockage of downstream units such as rectification units. The higher the conversion level for a given feedstock, the greater the amount of precipitate formed. This problem,
It is more serious at low hydrogen pressure and high reaction temperature.

The process according to the invention is 4.0 to 25.0% by weight, based on the weight of the carrier, preferably 10.0 to 25.
1. A Group VIII metal oxide, preferably nickel or cobalt oxide, most preferably NiO, on a porous silica-alumina support containing 0% by weight of silica.
0-6.0% by weight, preferably 2.5-3.5% by weight;
Molybdenum oxide, most preferably MoO ₃ from 12.0 to
25.0% by weight, preferably 12.0 to 18.0% by weight; and a phosphorus oxide, preferably P ₂ O _{5 in an amount} of 0 to 3.
A catalyst composition containing 0% by weight, preferably 0-2.0% by weight, is used. Most preferably, the carrier is gamma-alumina. Group VIII here is Group VIII of the Periodic Table of the Elements. The Periodic Table of the Elements referenced here is the CRC Handbo
It is found on the inside of the cover of ok of Chemistry and Physics 55th Edition (1974-1975). Other salt or oxide components that may be found in such catalysts are SO ₄ salts (0.8 wt%
Is present in less than) and Na ₂ O (present in less than 0.1% by weight). The silica-alumina support described above can be purchased or synthesized by methods well known to those skilled in the art.

For the preparation of the catalyst, a silica-containing support is impregnated with the required amounts of molybdenum oxide, a Group VIII metal oxide and, optionally, a phosphorus oxide, by conventional methods well known to those skilled in the art. To obtain a completed catalyst.

The Group VIII metal may be iron, cobalt or nickel and is supported on a support, for example as 10 to 30% by weight, preferably about 15% by weight metal nitrate. The preferred metal of this family is nickel, which is used as an approximately 16% by weight aqueous solution of nickel nitrate hexahydrate. Molybdenum can be supported on a carrier using, for example, an aqueous solution of 10 to 20% by weight, preferably about 15% by weight, of ammonium heptamolybdate (AHM). The phosphorus component, when used, can be prepared from 85% phosphoric acid.

The active metal and phosphorus can be supported on the catalyst carrier through filling the pores. Although it is possible to support each metal separately, if a compound of Group VIII metal and molybdenum is used, not only phosphoric acid but also hydrogen peroxide and citric acid (monohydrate) It is preferable to simultaneously impregnate with such a stabilizer.
The catalyst is preferably impregnated with a stabilized impregnation solution containing the required amounts of metal and citric acid by filling 95-105%, for example 97%, of the pore volume of the support.

Finally, the impregnated support is dried in an oven,
Then preferably 538 to 621 ° C (1,000 to 1,
Bake in a stream of air at 150 ° F for 20 minutes to 2 hours.

Preferentially removing sulfur and nitrogen from converted product streams having components having boiling points below 540 ° C.,
Hydroconversion processes, such as mild hydrocracking processes, are less affected by the quality of the unconverted product, rather, the primary concern is the quality of the distillate products from the hydroconversion process. Something like that is desired. The high heteroatom content of the distillate hydroconversion product is 343-540 ° C (650
˜1,000 ° F.) with an adverse effect on fluid catalytic cracking of heavier gas oils and strong distillate hydrotreating to severely limited levels of heteroatoms in distillate fuels. The need for adaptation is well known to those skilled in the art. 540 ° C. due to the demands on the catalyst composition
From a converted product stream having a boiling point component of less than (1,000 ° F) to a hydroconversion process such as mild hydrocracking that achieves effective levels of sulfur and nitrogen removal,
It becomes difficult to use a single catalyst. However, the catalyst used in the process of the present invention not only has an optimal micropore size that overcomes the diffusion limits for hydrotreating the converted product molecules, but also allows for poisoning inside the catalyst pellets. It is possible to achieve such a result because it does not contain large macropores.

[0034]

EXAMPLE A catalyst sample A whose properties are shown in Table 1 below,
B, C, D and E; and catalyst samples F, G and H, the properties of which are shown in Table 2 below, are catalysts prepared as described above and are used in the process of the present invention. Catalyst A
Carrier AX used in the treatment of the catalyst, Carrier E used in the treatment of the catalyst E
The properties of X and the support GX used to treat Catalyst G are set forth in Table 3 below. The catalyst is commercially available from American Cyanamide and has a diameter range of 0.89 to 1.04 mm.
Prepared with a silica-alumina support available in the form of (0.035-0.041 inch) extrudates.

The silica contents of the catalysts listed in Tables 1 and 2 are based on the weight of the catalyst support.

[0036]

[Table 1]

[0037]

[Table 2]

In Tables 3 and 4, suffix X
Represents a support for the catalyst, which is designated by the same symbol. The contact angle used to measure the median pore mode by volume, expressed in MPD (volume) of the support and the finished catalyst, is
They were 140 ° and 130 °, respectively.

[0039]

[Table 3]

[0040]

[Table 4]

Two commercially available hydrotreating catalysts are shown in Table 5 below. All of these catalysts are as-received catalysts sold for use in hydroprocessing of resids. American Cyanamide HDS-14
The 43B catalyst, Catalyst I, is referred to herein as the standard reference catalyst.

The values of the pore structure shown in Tables 1 to 5 are Nicromet.
It was measured using a rics Autopore 9220 mercury porosimeter. The table lists for reference the BET mean values determined by the Brunauer-Emmett-Teller technique.

[0043]

[Table 5]

A preferred feature of the catalyst used according to the invention is that it is a molybdenum oxide, preferably MoO _{3 as} described above.
However, the molybdenum gradient (MbG) of the catalyst is distributed in the above-mentioned porous alumina carrier in such a way that it has a value of 1.0 to 10.0. In the description of this specification and the accompanying claims, the phrase "molybdenum gradient" refers to the ratio of the molybdenum / aluminum atomic ratio on the outer surface of a given catalyst pellet to the molybdenum / aluminum atomic ratio on the inside of a given catalyst pellet. Means
It has a value of 1.0 to 10.0, preferably 1.0 to 6.0, most preferably 1.0 to 5.0. The atomic ratio is often measured by X-ray photoelectron spectroscopy (XPS), which is also called electron spectroscopy (ESCA) for chemical analysis.

[0045]

(Equation 3)

A molybdenum gradient was used in the preparation of the catalyst.
It is theorized to be strongly influenced by the impregnation of the catalyst support with molybdenum and subsequent drying of the catalyst. ESCA data on the outer and inner surfaces of the catalyst pellets is VG Sc
Obtained by Escalab MKII instrument using a 1253.6 eV magnesium X-ray source available from ientific. The atomic percentage value is calculated from the peak areas of the signals of molybdenum 3 _{p3 / 2} and aluminum 2 _{p3 / 2} by VG Sc
Calculated using the sensitivity factor supplied by ientific. The value of 74.7 eV for aluminum was used as the standard binding energy.

To determine the molybdenum / aluminum atomic ratio on the outer surface of a given catalyst pellet, the catalyst pellet was stacked flat on a sample holder and subjected to ESCA analysis. For the catalyst used according to the invention, the molybdenum / aluminum atomic ratio on the outer surface of the catalyst pellet is
The range of 0.12 to 0.75, preferably 0.12 to 0.
42. The molybdenum / aluminum atomic ratio of this outer surface is considerably larger than the Mo / Al atomic ratio of 0.03 to 0.09 of the catalyst surface disclosed in US Pat. No. 4,670,132.

In order to measure the molybdenum / alumina atomic ratio inside a given catalyst pellet, the catalyst pellet was crushed into a powder, placed fixed in a sample holder and
Subjected to CA analysis. For catalysts used according to the invention, the catalyst pellet interior (ie, the molybdenum / aluminum ratio at the powder interior location, which is estimated to correspond to the pellet interior location) is 0.08-.
The range is 0.15, preferably 0.11 to 0.12.

The usual method (ie atomic absorption method (A
A) or the molybdenum / aluminum atomic ratio of all catalyst compositions used according to the invention measured by inductively coupled plasma (ICP spectroscopy) is between 0.060 and.
Range of 0.075, preferably 0.062 to 0.071
Is. To measure the molybdenum / aluminum atomic ratio of all catalyst compositions, catalyst pellets were ground into powder and digested with acid to form an ionic solution. Then,
The solution was analyzed by AA or ICP to determine the Mo ion concentration, which was corrected to that of MoO ₃ . The concentration of alumina (Al ₂ O ₃ ) depends on other components (for example, N 2
i, Fe, Na, S) concentration was back calculated from the direct measurement.

To evaluate the intrinsic activity of the non-diffusion catalyst, the HDS Micro Activity Test (HDS-MAT) using model sulfur compounds as probe was used. The catalyst is 0.
Ground into fractions 250~0.595mm (30~60 mesh), at 399 ℃ (750 ° F), 10% H 2 S /
Two hours of presulfiding was performed with the H ₂ mixture. The presulfurized catalyst was exposed to a benzothiophene-containing feedstock and a hydrogen stream at 288 ° C (550 ° F). Fractions were taken periodically and the conversion of benzothiophene to ethylbenzene was analyzed by gas chromatography. HD
The results obtained in the S-MAT test are shown at the bottom of Tables 1 and 2, along with Mo and Ni gradients.

Tables 3 and 4 show the pore volume distribution and surface area of six silica-alumina supports with silica contents varying between 4 and 16% by weight. As the silica content increased from 4 wt% to 16 wt%, PV10
Pore volume in the region of ~ 16 nm decreases while total pore volume (TPV) and macroporosity (PV> 25 nm)
Will increase. Carrier TPV is 0.81 to 1.06 cm ³ / g
And the macroporosity is in the range of 0.07 to 0.34 cm ³ / g. The pore volume of pores with diameters in the range of 10 to 16 nm varies between 0.24 and 0.56 cm ³ / g, or between 32 and 77% of the pore volume of pores with diameters less than 25 nm. To do. A comparison of the pore volume distribution between the support and the finished catalyst shows that the pore volume in the 10-16 nm region remains unchanged after impregnation with the active metal.

In contrast to silica-alumina used in conventional cracking and hydrocracking catalysts, this type of silica-alumina has other unique characteristics. That is, the acidity of the support, shown in Table 3 as NH ₄ desorption, is independent of silica content. The method of mixing silica gel with alumina gel is not effective in increasing the acidity of the support and the finished catalyst.

N based on 5 silica-aluminas
The properties of i-Mo catalysts are compared in Table 1. Three types of impregnation stabilizers, hydrogen peroxide, citric acid and phosphoric acid were used to co-impregnate Ni and Mo onto the silica-alumina support. It was observed that the HDS-MAT activity decreased with increasing silica content. All catalysts listed in Table 1 showed high Mo gradients, except for catalyst D, which was stabilized with citric acid. To increase the HDS-MAT activity of the Ni-Mo catalyst on silica-alumina support with 16% silica, the calcination temperature was 593 ° C (1,100 ° F).
(Catalysts F and G cases). As can be seen in Table 2, the HDS-MAT activity of catalysts F and G is higher than the HDS-MAT activity of catalysts C and H. Therefore, citric acid is the most effective impregnation stabilizer to achieve high dispersion of Mo and uniform penetration of Mo across the catalyst extrudate.

Berty Reactor Hydrocracking A type of continuous stirred tank reactor (CSTR), the Berty Reactor, is used by the present invention in a diffusion controlled manner with a low deactivation rate. It was used to measure the hydrocracking activity of the catalyst. The catalyst was presulfided and the reaction was run for 38 hours at a single space velocity. Fractions of the sample were removed every 4 hours to measure boiling point distribution, Ni, V, S and precipitate content. The feedstock properties and operating conditions are listed in Table 6 below.

The hydrocracking activity was evaluated at 343 ° C. in the products when various catalysts were evaluated with the same feedstock under a certain mild hydrocracking condition as shown in Table 6. 6
Fraction boiling at temperatures below 50 ° F, and 538 ° C
Percentages of fractions boiling at temperatures below (1,000 ° F) were determined by comparison. Conversions at 343 ° + (650 ° F +) and 538 ° C + (1,000 ° F +) were calculated by the following formula.

[0056]

[Equation 4]

The boiling point distribution of all products is ASTM D-2.
887 "simulated distillation by gas chromatography". The precipitate content of all products is IP
375/86 "total precipitate in residual heavy oil". The total precipitate was the sum of insoluble organic and inorganic materials separated from the collection of residual heavy oil by filtration through filtration media, which was also predominantly insoluble in paraffinic solvents.

[0058]

[Table 6]

The data listed in Table 7 below is for Berty
Achieved by catalysts A, B, C and D of the present invention compared to the activity exhibited by catalyst I (standard catalyst) and catalyst J, both commercial hydrotreating catalysts, measured in reactor tests The results are shown.

The data listed in Table 7 are for catalysts A, B,
C and D are significantly higher than catalyst I at 343 ° C. +
Having a conversion of (650 ° F +); catalyst C has a value of 343 ° C + (650 ° F +) conversion approximately equal to catalyst J, while catalysts B and D have 343 ° +.
It is shown to exhibit greater activity than catalyst J for (650 ° F +) conversion; and that catalyst A exhibits a somewhat lower value of 343 ° C + (650 ° F +) conversion than catalyst J. . Catalysts A, B, C and D are all higher than catalyst I or J at 538 ° C + (1,000
0 ° F +) conversion value.

[0061]

[Table 7]

A comparison of conversion superiority over catalyst I having a bimodal pore structure is shown in the data listed in Table 8 below.

[0063]

[Table 8]

The data listed in Table 8 shows that catalysts A, B, C and D according to the present invention had 343 ° C. + (650 ° F.
+) Conversion shows an increase of 11-19% by volume over the conversion reached by catalyst I (ie standard catalyst), which leads to a relative increase in conversion of 37.9-65.5%. It shows that it corresponds. Catalysts A, B, C and D also showed an 8-14 vol% increase in 538 ° C + (1,000 ° F +) conversion, which was 10.3-17. This corresponds to a 9% increase. IP precipitate formation for these same catalysts shows a 0.1-0.3% reduction over catalyst I precipitate formation.

The results shown in Table 8 indicate that the performance of the silica-alumina based catalysts is significantly superior to prior art catalysts I or J.

[0066]

The presence of the catalyst used according to the invention, for example on a silica-alumina support, containing molybdenum oxide, nickel oxide and optionally phosphorus oxides and having a specific pore size distribution and molybdenum gradient. The mild hydrocracking of heavy oils containing residual oil underneath increases not only the more efficient conversion of residual oil feedstocks, but also the formation of precipitates. Is kept at a level below or similar to that achieved by conventional bimodal alumina-based catalysts.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Charles Nelson Campbell The Second United States, Texas 77642, Port Arthur, Highway 365, 3920, Apartment 248 (72) Inventor Bobby Ray Martin United States, Texas 77707, Beaumont, East Coldwood Drive 285 (72) Inventor Randall Hughes Petty United States, Texas 77651, Port Netches, Herbert Woods Drive 713

Claims (5)

[Claims] 1. A hydrocarbon feedstock having a substantial proportion of components boiling below 540 ° C., said hydrocarbon feedstock being contacted with a particulate catalyst at elevated temperature and hydrogen pressure of less than 10.5 MPa. In a mild hydrocracking process, wherein the catalyst is supported on porous alumina containing 4.0 to 25.0 wt% silica, based on the weight of the support, MbG having the formula: : [Equation 1] The oxide of a Group VIII metal is 2.0, in which the molybdenum gradient (MbG) defined in 1 has a value of 1 to 10.
-6.0 wt%, molybdenum oxide 12.0-25.0 wt%, and phosphorus oxide 0-3.0 wt%; the catalyst has a total surface area of 150-250 m ² / g; and less than 10 nm. The diameter of the pores is from 20.0% of the total pore volume of the catalyst.
40.0%, pores having a diameter of 10-16 nm make up 28.4-34.1%, pores having a diameter above 16 nm make up 30.0-50.0%. , And with a pore size distribution such that macropores having a diameter greater than 25 nm make up 25.0 to 40.0% of the total pore volume of the catalyst, a total fineness of 0.75 to 0.92 cm ³ / g. A hydrocracking method having a pore volume. 2. The method of claim 1, wherein the catalyst contains 0.1 to 2.0 weight percent phosphorous oxide. 3. A process according to claim 1 or claim 2 in which the catalyst contains 16 to 25% by weight of silica. 4. The group VIII metal is nickel.
4. The method according to any one of 3 to 3. 5. The catalyst comprises 2.5 to 3.5 wt% NiO and 12.0 to 18.0 wt% MoO _3.
The described method.