JPH03212493A - Manufacture of lubricating oil having low pour point - Google Patents

Abstract

PURPOSE: To obtain a high quality lubricating oil containing a hydrocracking lubricating oil having a low pouring point by bringing a specific bright stock raffinate into contact with a specified zeolite-based dewaxing catalyst under specific conditions.

CONSTITUTION: A bright stock raffinate (A) comprising a demetallized petroleum fraction free of components having a boiling point of 371°C or below is brought into contact with a dewaxing catalyst (B) under the conditions of a temperature of 260-482°C, a pressure of 14.8-242.4 bar, a liquid hourly space velocity of 0.2-20 and a hydrogen circulation rate of 89-3560 m³/m³ to obtain the desired lubricating oil, wherein the dewaxing catalyst comprising a porous composite composed of a zeolite having a constraint index of 1-12 which constitutes 35-75 wt.% of the composite and a matrix, wherein not less than 60 vol.% of pores of the composite having a diameter not greater than 10 nm, and the composite having a particle density of not less than 1.0 g/cc.

COPYRIGHT: (C)1991,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to the treatment of high molecular weight vacuum distillate oils, such as bright stock raffinate, to reduce the pour point.

BACKGROUND OF THE INVENTION Suitable raw materials for lubricant refining contain lubricant stocks that have certain properties such as suitable viscosity, stability against oxidation and maintenance of flowability at low temperatures. The purification process for isolating this lubricant stock consists of a series of subtraction unit operations to remove undesirable components. The most important of these unit operations are distillation, solvent refining, and dewaxing, which would reconstitute the crude oil if all separated functions were recombined. Each is essentially a physical separation step.

The complexity of the molecular structure of the required components is reflected in the vacuum distillation of the first step in the lubricant purification process. In vacuum distillation, the feedstock is divided into four boiling fractions, each with a different viscosity and a varying mixture of aromatics, naphthenes, paraffins, resins and asphaltenes. The separation must be precise, as the resulting viscosity and composition cannot be adjusted in subsequent purification steps.

The lightest fraction of the vacuum distillation stage is the vacuum column overhead, which has a boiling range of up to about 700°F (370°C) and is usually sent to a fuel refinery for conversion to lighter products. The remaining three fractions can be used in the production of lubricant stocks.

The second fraction, light neutral distillate, is
It has a boiling range of about 700 and 850°F (371 and 454°C) and is used to produce low viscosity oils. Boiling range 850 to 1000°F (454 to 5
The third fraction, heavy neutral distillate, at 38° C.) is used to produce high viscosity oils. The fourth fraction, vacuum residual oil, does not boil under vacuum and results in a lubricating oil base called "bright stock." This vacuum residual oil contains all the asphaltite and much of the resin and metals in the crude feed.

Crude oils suitable for lubricant production have become difficult to obtain due to depleted stocks and it can be difficult to obtain a steady and adequate supply from known processes. Therefore, it has been noted for some time that it is desirable to modify crude fractions, which would normally be considered unsuitable, in order to produce good lubricating oils. However, the complexity of the molecular makeup of lubricating oils requires consideration of many varying factors in developing a virtually useful process for producing lubricant stocks from crude petroleum oils.

"Hydrocracking," sometimes referred to as "harsh hydroprocessing," has been proposed to accomplish such reforming. In this process, a suitable fraction of a low grade crude, such as California crude oil, is catalytically reacted with hydrogen under pressure. The process is complex, as a portion of the oil has a reduced molecular weight, making it unsuitable for lubricants, but at the same time a substantial fraction of the polycyclic aromatics are hydrogenated to form naphthenes and paraffins. Since this component reduces the viscosity index and stability of the stock, process conditions and catalyst selection are made to obtain optimal conversion of the polyaromatic content of the stock. Additionally, paraffins can undergo isomerization in the hydrocracking process, giving the final lubricant product good viscosity index properties. The term "hydrocracking" is used for processes such as those described above, in contrast to the process described above, where the purpose of "hydrotreating" is to stabilize the lubricant base stock produced by hydrocracking. . Hydrocracking and hydrotreating stages can also be differentiated by the amount of hydrogen consumed, generally the hydrocracking stage is about 178-356+++3/m3
(1000-200O3CF/bbl) while consuming
The hydrotreating stage only consumes about one-tenth.

Hydrocracking processes for increasing the availability of lubricating oils have interesting features that are not immediately apparent. Therefore, the composition and properties of the hydrocracked stock are not particularly influenced by the source and nature of the crude product within the shell. That is, they tend to be significantly similar, unlike fractions produced from different crude products in the conventional manner.

This method therefore ensures that the refinery does not have to depend on a particular crude oil, which is all its advantages.

Hydrocracked lubricant stocks tend to become unstable in the presence of air when exposed to sunlight. Exposure to sunlight results in the formation of an unacceptable sludge, sometimes rapidly and in considerable quantities. Additionally, some of the hydrocracked lubricants darken and form a haze. Several methods have been proposed to correct this instability, such as U.S. Pat.
No. 3,530,061, No. 4,162,962, No. 3,530,061 and No. 3.852.207
listed in the number.

Hydrocracked lubricants generally have unacceptably high pour points and require dewaxing. For example, U.S. Patent No. 3.700
．． No. 585 proposes a catalytic method for dewaxing. Hydrotreating after catalytic dewaxing is described in U.S. Pat.
No. 137,148. U.S. Patent No. 4,2
No. 83,271, No. 4, No. 283.272 and No. 4,
No. 414,097, hydrocracking a hydrocarbon feedstock,
A method is taught for the production of a dewaxed lubricating oil base comprising catalytically dewaxing a hydrocrackate and further hydrotreating the dewaxed hydrocrackate, wherein for the dewaxing step A catalyst composition comprising zeolites ZSM-5, ZSM-11 and ZSM-23 has been used.

There is a need for a method that can effectively produce modern, high-quality lubricants and lubricating oils, including hydrocracked lubricating oils, with low pour points from replaceable and readily available low-grade crude feedstocks. be.

``Structure of the Invention The present invention provides for the catalytic hydrogenation of hydrocarbon feedstock effluents boiling above 288°C (550°F) in which a supported catalyst composition comprises a zeolite and a matrix and optionally a Group I metal. An energy efficient continuous process for producing a dewaxed hydrocracked lubricant stock from a hydrocarbon feedstock effluent through a dewaxing process is provided.

According to the present invention, there is provided a cyclic catalytic dewaxing process for improving the pour point of demetalized petroleum fractions free of components with a boiling point below 371°C, the process comprising bright stock raffinate at a temperature of 260-482°C. 1 pressure 14.8~2
42.4 bar, a liquid hourly space velocity of 0.2 to 20 and a hydrogen circulation rate of 89 to 3560 m3/m' with a dewaxing catalyst, which catalyst has a Constraint Index.
1-12 zeolite and zeolite 35-75
percent by weight of a matrix porous composite, at least 60 volume percent of the pores of the composite have a diameter of 20 nm or less, and the composite has a diameter of at least 1. It has a particle density of Og/cc.

In the catalytic (catalytic) treatment of heavy petroleum fractions, it is generally considered desirable that the pore structure of the catalyst be as open as possible. That is, the average pore diameter is large while maintaining a reasonable surface area to reduce diffusion limitations. Thus, for example in the case of petroleum residue demetallization catalysts, it is desirable to minimize the number of pores with a diameter of 7.5 nm or less.

Unexpectedly, in the catalytic dewaxing of heavy oil fractions, such as lubricating oil base stocks, the diameter of the dewaxing catalyst complex is 2
It has been found that it is desirable to maximize the number of pores below 0 nm. In particular, it has been found that the aging rate of catalysts in dewaxing reactions is influenced by the pore size distribution of the catalyst. As shown in the examples, the beneficial effect of catalyst pore size distribution becomes greater as the average molecular weight of the feedstock increases.

In the drawings, Figure 1 is a plot of pore diameter versus pore volume (cc/gm), Figures 2 and 3 are plots of days of circulation versus reaction temperature, and Figures 4 and 5 are also plots of days of circulation versus reaction temperature. The plot, Figure 6, is a plot of days in flow versus reactor temperature.

In the present invention, the aging rate of the dewaxing catalyst in dewaxing has been reduced. Therefore, the cycle starting temperature in the second and subsequent cycles in a multi-cycle dewaxing operation is reduced. The ability to reduce the aging rate of the dewaxing catalyst is
Allowing a longer period between oxygen regeneration and hydrogen reactivation cycles, thus increasing the overall life of the catalyst. It should be noted that aging rate can be expressed in terms of the daily increase in operating temperature required to maintain a product with a constant pour point. The advantages of the present invention apply particularly to bright stock raffinate feedstocks, which produce within the fastest catalyst aging rates and whose physical properties such as pore volume, pore size distribution and particle density significantly influence catalyst performance. give. A good example of this is in the structure of demetalization catalysts,
In this catalyst, the majority of pores must be larger than the 10r+n+ range to prevent pore clogging by deposited metals and to allow diffusion of Ni and V-containing porphyrins. The structure of the demetalization catalyst is related to the importance of the balance between the required pore size distribution and large surface area for the required activity to occur.

In the present invention, by comparison, the catalyst is a porous mixture, with at least 60 percent of the pores having a diameter of 20 na+ or less by mercury porosimetry. The average pore size of the mixture is preferably 15 nm or less, more preferably 10 nm, and in some embodiments 7 nm or less, even 4 nm.
r+m or less. Preferably, the particle density of the porous composite is at least 1.0 g/cc.

The restraint index of the zeolite component of the catalyst is 1-12. The method for measuring the restraint index is described in U.S. Patent No. 4,0.
No. 16,218 describes this in detail.

The constraint index (CI) of typical materials is as follows.

CI (Test temperature, .C) ZSM-40,5 ZSM-56-8,3 ZSM-115-87 ZSM-122,3 ZSM-2005 ZSM-227,3 ZSM-239,I ZSM-3450 ZSM-354, 5 ZSM-483, 5 ZSM-502, I TMA Offretite 3,7 TEA Mordenite 0,4 Clinoptilolite 3.4 Mordenite 05 (316) (371-316) (371-316) (316) (371) ( 427) (427) (371) (454) (538) (427) (316) (316) (510) (316) REV 0.4 (316) Amorphous silica-alumina 0.6 (53B) Dealumination Y O,5 (510) erionite
38 (318) Zeolite Beta 0.6-2
．． 0 (316-399) Test conditions, such as temperature, may be selected to establish more than one value for the constraint index of a particular zeolite. This is why ZSM-5, ZSM-11
and explains the range of restraint index of zeolites such as zeolite beta.

Preferably, the crystal size of the zeolite is in the range of 0.02 to 0.05 micrometers. Although not required, the catalyst composition generally includes a Group I metal, which, when present, can be substituted or impregnated with the composition by known techniques. Or they may mix physically and intimately. The amount of Group I metal in the catalyst composition is 0, based on the total weight of the catalyst composition.
110 to 10 weight percent, preferably about 0°1
from about 3 weight percent, most preferably from about 0.2 to about 1 weight percent. Group I metal components are platinum, palladium, iridium, ruthenium, cobalt, nickel, copper, molybdenum and mixtures thereof.

The preferred metal is nickel. Group I metals may be used alone or in combination with Group I metals such as chromium, molybdenum, tungsten, and mixtures thereof.

Particle size (effective or hydraulic diameter) of the preferred form of catalyst
is in the range of 0.75 to 3.21. The binder or matrix is suitably an alumina other than alpha alumina, preferably gamma alumina. - Inside the shell is small particle alumina with a packing density of 0.5 to 0.6 g/cc. Matrix is 0.95 to 1.50g/cc
It is characterized by the particle density of Alumina l hydrate (pseudoboehmite) can be converted to analogs of desired density during catalyst formation.

The alumina source for the matrix used in catalyst preparation preferably has a moisture content of 20 to 30 weight percent. By way of illustration, the alumina monohydrate used as the source of matrix material in the examples has a water content of 28 percent. Preferably, the alumina source is convertible to gamma alumina.

Gamma alumina is an alumina phase that results from calcination at temperatures below about 1000'F.

As seen in the examples, δ alumina has a temperature of about 927'C (
Results of calcination at a temperature of 1700°F.

In the preferred catalyst preparation process, the zeolite, Group I metal, and binder or matrix are mixed into a homogeneous mixture. An important characteristic during the mixing stage is the moisture content of the mixture. For mixtures used for extrusion resulting from mixing, the moisture content is expressed as the ash content of the mixture, which may range from 40 to 60% by weight. Moisture content is also expressed as solids content, with solids content ranging from 45 to 60. Preferably it is 42 to 55 weight percent. Mixing is carried out at a temperature ranging from 50 to 1 OO'F. The mixture may also contain 0.05-5% by weight of an extrusion aid such as polyvinyl alcohol.

Extrusion is performed in conventional equipment and produces particles with a length to diameter ratio of at least 2.

The matrix precursor is alumina l-hydrate (i.e.
pseudoboehmite), which is converted to a denser analogue during catalyst formation.

The feedstock to the dewaxing unit is demetalized and heated to approximately 700°F.
It is a fraction obtained by vacuum distillation of crude oil that does not contain components with a boiling range of It is based on.

The process conditions in the catalytic dewaxing equipment are summarized in the table below.

Dewaxing Dewaxing conditions Suitable pressure range, bar (psig) 14.8 (200)
~242.4 (3000) Suitable range 1
4.8 (200) to 140 (2000) temperature, suitable range, 'C260 to 482 suitable range 2
60-375LH3V*, possible range 0.2
~20 suitable range 0.5~5 H, gas, m'/m3 (SCF/bbl) **
Appropriate range: 89 (500) to 3560 (2
0000) Suitable range: 89 (500) to 5
34 (3000)*LH3V=Liquid hourly space velocity, ie, feed volume per unit catalyst volume per unit time* *S CF/bbl=Standard cubic feet per barrel A preferred embodiment of the invention is described in the following examples.

Example 1 Lubricant dewaxing catalyst was 65 percent ZSM-5,3
A mixture consisting of 5 percent coarse-grained, high chemical purity, low density, high surface area alpha alumina monohydrate (pseudoboehmite), nickel nitrate hexahydrate, and sufficient water to form a pasty mixture. Prepare, mix this mixture and add 1.6n++n (1/1
6 inch) cylindrical pellets. The catalyst was heated to 482°C (900'F) (2.8°C) in nitrogen.
/min) for 3 hours, then heated to 538°C (100°C) in air for 3 hours.
00F) for 3 hours. Through this step, alpha alumina monohydrate was converted to gamma alumina.

The physical properties and pore size distribution (measured with a mercury porosimeter) are shown in Table 1. The catalyst in this example is what is referred to as a medium pore diameter catalyst. This catalyst has 60 percent pores (measured with a mercury porosimeter) with a diameter of less than 2 Or+m.

Example 2 Lubricant dewaxing catalyst was 65 percent ZSM-5,2
The same alpha alumina 1 used in Example 1 at 1%
21 percent of hydrate (pseudoboehmite), 14
% delta alumina, nickel nitrate hexahydrate, and sufficient water to form a pasty mixture, the mixture is mixed and prepared in the conventional manner to form a 1/16 inch (1.6 mm) Manufactured by molding into cylindrical pellets. δ alumina is α alumina
The hydrate was prepared by calcination in air at 927°C (1700°F) for 4 hours. This catalyst was prepared in nitrogen at 482°C (
900'F) (heated at 2.8°C/min) for 3 hours, then 538°C (i.o.) in air.

OoF) for 3 hours. The physical properties and pore size distribution (measured with a mercury porosimeter) are shown in Table 1. The catalyst in this example is what is called a large pore diameter catalyst. This catalyst has 44% pores (measured with a mercury porosimeter) with a diameter of 20% m or less.

Example 3 The lubricant dewaxing catalyst was 65% ZSM-5, a finely divided dense high chemical purity alpha alumina l-hydrate;
Prepare a mixture of Keith alumina (pseudoboehmite from Keith Corporation), nickel nitrate hexahydrate, and sufficient water to form a pasty mixture, and mix the mixture. The pellets were combined and formed into 1.6 mm (1/16 inch) cylindrical pellets using conventional methods. The catalyst was heated at 482°C (90°C) in nitrogen.
0° F. (heating at 2° 8° C./min) for 3 hours and then precalcined in air at 1000° F. for 3 hours. Through this step, alpha alumina monohydrate was converted to gamma alumina. The physical properties and pore size distribution (measured with a mercury porosimeter) are shown in the following table. The catalyst of this example is called a small pore diameter catalyst. This catalyst is 4
It has an average pore diameter of nm, with 92 percent of the pores (measured with a mercury porosimeter) having a diameter of 20% m or less.

Table 1 Example 1 Example 2 Ni, weight% 0.95 0.98 Na, ppm 155 140 Density + g/c
c True 2.616 2.229 Particles 0.992 0.896 Filling 0.60 0.56 Pore volume (B ET), cc/g O,6260,777 Surface area, +*”/g 358 326 Pore volume distribution, XI Occ/g 30-50 0.46 50-80 1 26 80-100 0.54 100-150 0 63 +50-200 0.27 200-300 0.26 300+ 1.76 Example 4 0.52 0. 69 0.31 0.62 0.48 0.47 2.90 Example 3 Approximately 1.0 30 2.616 1.407 0.71 0.328 13 0.29 0.67 0.70 1.40 0 .60 0.16 14 Paraffinic North Sea Heavy Neutral for the catalysts of Examples 1 and 2.
The dewaxing of Heavy Neutral and Bright S Lock raffinates was tested. The properties of the raw materials are shown in Table 2.

Both catalysts were capable of providing products with pour points of -6.6°C (20'F). The aging rate of the catalyst can be determined by adjusting the reaction temperature to compensate for deactivation, while maintaining all other conditional constants.
The desired pour point of -6.6°C (20°F) was maintained.

In comparing the performance of medium-pore and large-pore diameter catalysts, only a small effect on the aging rate was observed when using the medium-pore diameter of the heavy neutral raffinate outlet (Figures 2 and 3). Figure 3).

However, in the case of bright stock raffinate, a much larger effect on the aging rate is observed for the same catalyst (Figures 4 and 5). In this way, smaller pore diameter catalysts are more suitable for processing heavier feedstocks.

Table 2 Stadfjord (Sta) used in this study
Raffinate Properties of Heavy Neutral and Bright Stock Heavy Neutral 48, 8 (120) 11, 550 4, 550 1, 462 30.700 13, 640 110, 000 97, 000 0, 200 0, 13G 0,200 0.100 250 0,200 67,000 Pour point, 'C('F) K, V, 0 100°C, C8 K, V, 0 300°C, as Refractive index 070°C Specific gravity, AP I Hydrogen 1 Weight % Nitrogen + PPm Basic nitrogen, ppm 1% by weight Sulfur 1% by weight Aliphatic sulfur Nt+ ppm V, ppm Fe, ppm Cu, ppm Water azeotropic distillation I PpIll Bright Stock 48, 8 (120) 27, 500 8 , 890 1.471 27, 500 13, 490 420000 253, 000 0, 380 0, 230 0, 400 o, io.

O,350 9000 Table 2 (Continued) Heavy Neutral Tone, ASTM Oil 1.750 Furfural, ppm 2.000 Residual Carbon,
MCRT, weight% 0.030 total acid value
0.280 Flash point (Cleveland open type) % formula % Extraction in petroleum wax 1% by weight 79.570 Distillation (volume % of distillate) IBT (initial boiling point), °C ('F) 404 (759,5
) 5% by volume 476(883,0) 10% by volume 486(906,0) 20% by volume
49g (929,3) 30% by volume 5
07 (943,7) 40% by volume 512 (9
53,7) 50% by volume 517(962,3
)60 volume% 522 (971,9) 70 volume% 52g (982,4) 80 volume%
534 (993,9) 90% by volume
544 (1012,4) 95% by volume 554
(1029,9) EP (end point) 560 (1039,8) Menishiha M 11111 Bright Stocks, oo.

7,000 0,470 0,200 561.000 745.000 75,340 412(774,8) 511(951,2) 539(1003,1) 557(1035,1) 567(1052,7) 578( 1072,4) 588 (1091,3) 599 (1109,8) 602 (1115,2) C Example 5 Figure 6 shows the performance of the intermediate hole and small hole dewaxing catalyst in the dewaxing of Stadtfjord pride stock. It shows. Process conditions were LH3V-〇, 5.28.6 bar (400 psig) and 445 m3/m3 hydrogen/m3 hydrogen/oil (2500 S CF [(t/bbl)]. For bright stock raffinate dewaxing, small hole Keith alumina This example shows that the catalyst based on the pores has better performance than the mesopore catalyst.

[Brief explanation of drawings]

Figure 1 is a plot of pore diameter versus pore volume (cc/gm); Figures 2 and 3 are plots of days in circulation versus reaction temperature; Figures 4 and 5 are also plots of days in circulation versus reaction temperature; Figure 6 is a plot of days in circulation versus reactor temperature. M number of patent attorneys Mobil Oil φ Corporation agent Patent attorney Aoyama Ao Haka 1 person 59 &, C'F U; Mitsuru? I laziness (', A)

Claims (1)

[Claims] 1. Temperature 260-482°C, pressure 14.8-242.4
bar, liquid space velocity 0.2-20, hydrogen circulation ratio 89
contacting a bright stock raffinate with a dewaxing catalyst at ~3560 m^3/m^3, said catalyst comprising a porous composite of a zeolite and a matrix with a restraint index of 1 to 12; 371°C or less, comprising 35 to 75 weight percent of the composite, at least 60 volume percent of the pores of the composite have a diameter of 20 nm or less, and the composite has a particle density of at least 1.0 g/cc. A cyclic catalytic dewaxing process for improving the pour point of demetallized petroleum fractions free of boiling point components. 2. The method according to claim 1, wherein said zeolite is ZSM-5. 3. The above catalyst further contains 0.01-1 based on the weight of the composite.
3. A method according to claim 1 or 2, comprising zero Group VIII metals. 4. The method of claim 3, wherein said metal is nickel. 5. Any one of claims 1 to 4, wherein said matrix comprises small particle alumina having a packing density of 0.5 to 0.6 g/cc and a particle density of 0.95 to 1.50 g/cc. the method of. 6. The method according to any one of claims 1 to 5, wherein the average pore diameter of the composite is 15 nm or less. 7. The method according to any one of claims 1 to 6, wherein the average pore diameter of the composite is 10 nm or less. 8. The method according to any one of claims 1 to 7, wherein the composite has an average pore diameter of 7 nm or less. 9. The method according to any one of claims 1 to 8, wherein the composite has an average pore diameter of 4 nm or less. 10. The method according to any one of claims 1 to 9, wherein the zeolite has a crystal size of 0.02 to 0.05 micrometers. 11. Claims 1-10 wherein the pour point of the dewaxed product is at least 39°C (70°F) lower than the bright stock.
The method described in any of the above. 12. According to any one of claims 1 to 11, said contacting is carried out at a temperature of 375° C. or less, a pressure of 140 bar or less, a hydrogen circulation rate of 534 m^3/m^3 or less and a liquid hourly space velocity of 0.5 to 5. Method.