Catalyst for the first hydrodemetalization step in a hydroprocessing system with multiple reactors for the improvement of heavy and extra heavy crudes

Abstract

An improved catalyst for hydrodemetallization of heavy crude oils and residua is disclosed. The catalyst is adopted for fixed bed hydroprocessing units. The invention is characterized for having a large pore diameter catalyst principally for hydrodemetallization of heavy oil and residue in a first reactor of a multi-reactor process. The catalyst has high demetallizing activity and high metal deposition capacity which results in good stability with time on stream (TOS). The hydrorefining catalyst is obtained by kneading a porous starting powder principally composed of gamma-alumina and having a pore capacity of 0.3-0.6 ml/g or larger and a mean pore diameter of 10 to 26 nm, extrudating and calcining, and after that supported with active metals component of elements belonging to groups VIIIB and VIB of the periodic table.

Claims

1. A catalyst for a first hydrodemetallization step of heavy crudes, said catalyst comprising a gamma phase alumina support having on its surface a catalytically effective amount of molybdenum and cobalt present as oxides or sulfides, said catalyst obtained by a method including the steps of forming a dry boehmite mixture consisting essentially of two different dried boehmites having different pore volumes and different surface areas, peptizing said dry boehmite mixture with nitric acid, forming said peptizing mixture into extrudates, calcining said extrudates to form said gamma alumina support, impregnating said gamma alumina support with a solution containing Mo and Co, drying the gamma alumina support and calcining to obtain said catalyst, wherein said catalyst comprises 8 to 12% by weight molybdenum oxide or molybdenum sulfide and 2.0 to 2.5% by weight cobalt oxide or cobalt sulfide, and 85.5 to 90% by weight a gamma phase alumina, said catalyst has a cylindrical shape with a diameter of 1.59 mm, a compact density of 0.86 to 0.93 cm.sup.3/g, a crushing strength of 3.9 to 4.2 kg/cm.sup.2, a pore volume of about 0.36 to 0.55 cm.sup.3/g, a surface area of 102-120 m.sup.2/g, and average pore diameter of 11.8 to 21.8 nm, which is determined by means of nitrogen adsorption, said alumina support having 99% of its pores having a diameter greater than 2 nm, a pore volume distribution of less than 5 nm in an amount of 3 to 12.5 vol %, 5-10 nm in an amount of 10.5 to 34.8 vol %, 25-50 nm in an amount of 8.5-44.5 vol % and greater than 50 nm in an amount of 5 to 65.2 vol %.

2. The catalyst of claim 1, wherein said extrudates are calcined at a temperature in the range of 500550 C.

3. The catalyst of claim 1, wherein said mixture of boehmites comprises a first boehmite having a surface area of 230 m.sup.2/g and a pore volume of 0.50 ml/g and a second boehmite having a surface area of 100 m.sup.2/g and a pore volume of 0.77 ml/g.

4. The catalyst of claim 1, wherein said catalyst has a surface area of 102 m.sup.2/g, a pore volume of 0.54 cc/g and average pore diameter of 21.5 nm.

5. The catalyst of claim 1, wherein said catalyst has a surface area of 120 m.sup.2/g.

6. The catalyst of claim 1, wherein said catalyst has a pore volume of 0.36 cc/g.

7. The catalyst of claim 1, wherein said catalyst has an average pore diameter of 11.8 nm.

8. The catalyst of claim 1, said catalyst has pores with a pore diameter less than 5 nm in an amount of 12.5%, a pore diameter in the range of 5-25 nm in an amount of 74%, and pores greater than 25 nm in an amount of 13.5%.

9. A catalyst for a first hydrodemetallization step of heavy crude oil, said catalyst comprising 8 to 12% by weight molybdenum oxide or molybdenum sulfide, 2.0 to 2.5% by weight cobalt oxide or cobalt sulfide, and 85.5 to 90% by weight of a gamma phase alumina support, where said catalyst has a cylindrical shape with a diameter of 1.59 mm, a compact density of 0.86 to 0.93 cm.sup.3/g, a crushing strength of 3.9 to 4.2 kg/cm.sup.2, a surface area of 102 to 120 m.sup.2/g, a pore volume of 0.36 to 0.55 cm.sup.3/g, an average pore diameter of 11.8 to 21.5 nm, a pore volume distribution of less than 5 nm in an amount of 3 to 12.5 vol %, 5-10 nm in an amount of 10.5 to 34.8 vol %, 10-25 nm in an amount of 9.1 to 39.2 vol %, 25-50 nm in an amount of 8.5 to 44.5 vol %, greater than 50 nm in an amount of 5 to 65.2 vol %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The manner in which the foregoing and other objects are achieved in accordance with the present invention will be better understood in view of the following detailed description and accompanying drawings, which form a part of this specification, and wherein:

(2) FIG. 1 is a flow diagram showing the steps (A-G) for manufacturing a hydroprocessing catalyst of the present invention, in which (A) refers to the drying of boehmites, (B) is the mixing of boehmite powder, (C) is the peptization of boehmite with HNO.sub.3, (D) is the preparation of extrudates, (E) is the drying and calcination of the support, (F) is catalyst preparation, and (G) corresponds to the drying and calcination of the catalysts.

(3) FIG. 2 is a flow diagram showing the steps (H-M) for activation or pretreatment of catalysts of the present invention, where: (H) refers to catalyst loading, (I) a hemiticity test of the reactor, (J) a sulfidation procedure, (K) reaction conditions, (L) time-on-stream of the reaction, and (M) corresponds to the analysis of the reaction products.

(4) FIG. 3 shows the heavy crude oil hydroprocessing activities for a typical CoMo/Al.sub.2O.sub.3 (CoMo/Catapal C1 & Catapal 200) supported catalyst of the present invention with a mixed feedstock of Maya and diesel up to 120 h time-on-stream (Catalyst 1, 11.8 nm).

(5) FIG. 4 shows the heavy crude oil hydroprocessing activities for a typical CoMo/Al.sub.2O.sub.3 (Catapal 200) supported catalyst invention with a diluted feedstock up to 120 h time-on-stream (Catalyst 2, 26.8 nm).

(6) FIG. 5 shows the heavy crude oil hydroprocessing activities for a typical CoMo/Al.sub.2O.sub.3 (Pural HT 100 and Pural SB) supported catalyst invention with a mixed feedstock of heavy crude and diesel up to 120 h time-on-stream (Catalyst 3, 21.5 nm).

(7) FIG. 6 shows the comparison of performance for three different alumina support compositions for CoMo catalysts of the present invention for hydrodemetallization of heavy crude oil after 120 h TOS.

(8) FIG. 7 shows the heavy crude oil hydroprocessing activities for a typical CoMo/Al.sub.2O.sub.3 (Catapal C1 and Catapal 200) supported catalyst with a pure Maya heavy crude oil up to 1000 h time-on-stream (Catalyst 1, 11.8 nm).

(9) FIG. 8 shows the performance for a CoMo/Al.sub.2O.sub.3 (Catapal C1 and Catapal 200) supported catalysts with pure Maya crude up to 1000 h of time-on-stream, showing the metal deposition along with time-on-stream.

DETAILED DESCRIPTION OF THE INVENTION

(10) The catalyst is adapted for fixed bed hydroprocessing units. The catalyst of the present invention is characterized as having a large pore diameter principally for hydrodemetallization of heavy oil and residue in a first reactor of a multi-reactor process. The catalyst has high demetallizing activity and high metal deposition capacity which results in good stability with time on stream (TOS). The hydrorefining catalyst is obtained by kneading a porous starting powder principally composed of gamma-alumina and having a pore capacity of 0.3-0.6 ml/g or larger and a mean pore diameter of 10 to 26 nm, extrudating and calcining, and after that supported with active metals component of elements belonging to groups VIIIB and VIB of the periodic table.

(11) Our invention is entitled Catalyst for a first-step hydrodemetallization in a multi-reactor hydroprocessing system for upgrading of heavy and extra-heavy crude oils for improved textural properties of catalysts and their evaluation, the step wise drawing shows the detail preparation method of catalyst.

Stepwise Description of Supports and Catalysts Preparation

(12) The preparation of support and catalysts are depicted in FIG. 1, which is completed in steps A-G. The principal step is the peptization of aluminas that is responsible for the strength of catalysts as well as generation of macropores due to the inter-particle distance. Boehmite aqueous suspensions were acidified (peptized) with diluted nitric acid at room temperature to produce colloidal sol systems.

(13) The required quantity of aluminum oxyhydroxide (boehmite) is first dried at 120 C. for 5 h (A). The following steps are dry mixing of different boehmites (B), and mixing continuously with 3.5% (volume/volume) of HNO.sub.3 and distilled H.sub.2O (C). The mixture is then added to the mixer slowly with continuous mixing with the amount of deionized water necessary to obtain an homogeneous paste adequate to be extruded (D). The extrudates obtained with the paste are maintained at 20-25 C. for 12-18 h, and then they are dried at 100-120 C. for 2-6 h, and calcined at 500-600 C. for 3-5 h, using a heating ramp of 2 C./min to obtain gamma alumina (E). The calcined support was impregnated with the active metal in a sequential impregnation method (F) using a typical group IV metal in the first step and group VIIIB as promoters were used in a second step. The catalysts were dried at room temperature, 120 C. for 12 h, and finally calcined at 450 C. for 4 hours (G). The catalysts prepared with this method with variation of support composition and their physico-chemical properties are those presented in Table 1.

(14) TABLE-US-00001 TABLE 1 Properties of catalysts, indicating the various catalysts composition and their physical properties. Catalysts properties Cat-1 Cat-2 Cat-3 Support composition, wt. % Catapal C1 50 Catapal 200 50 100 Pural SB 50 Pural TH 100 50 Catalyst composition, wt. % MoO.sub.3 10.01 9.98 9.99 CoO 2.2 2.2 2.1 Catalyst physical properties Shape Cylindrical Cylindrical Cylindrical extrudate extrudate extrudate Size, in 1/16 1/16 1/16 Density of extrudates, cc/g 0.86 0.91 0.93 Crushing strength 4.2 3.8 3.9 (grain-to-grain), kg Specific surface area, m.sup.2/g 120 56 102 Average pore diameter, nm 11.8 26.8 21.5 Total pore volume, ml/g 0.362 0.479 0.546 % Micro-pore (d < 2 nm) 0.81 0.62 0.53 volume, ml/g % Meso-pore (2 d 50 42.5 33.8 29.3 nm) volume, ml/g % Macro-pore (d > 50 nm) 56.6 65.6 70.2 volume, ml/g Pore volume, cc/g >5 nm 12.5 3.0 4.2 5-10 nm 34.8 2.6 10.5 10-25 nm 39.2 9.1 33.9 25-50 nm 8.5 20.2 44.5 50-100 nm 4.0 37.5 5.2 >100 nm 1.0 27.7 1.7

Stepwise Description of Catalyst Pretreatment and Catalytic Test

(15) The reactor was operated in a fixed bed mode using up-flow and down flow modes. FIG. 2 is a schematic representation of the methodology used for the micro and bench scale reaction evaluation of the catalysts described in the examples of the present invention. In step (H), the reactor is loaded with 10 mL of catalyst with 10 mL of inert material (SiC). Stage (I), corresponds to the test of the equipment at a pressure 10 higher than the one used in normal operation in order to detect any leak in the experimental set up. The stage (J) represents the sulfidation of the catalyst, performed with gasoil from the atmospheric distillation of petroleum (SRGO) to which 2 wt % sulfur was added (DMDS+SRGO). The following operating conditions were used for the sulfidation of the catalyst: reaction temperature of 320 C., pressure of 28 Kg/cm.sup.2, LHSV of 2.0 h.sup.1 and hydrogen/hydrocarbon ratio of 356 m.sup.3/m.sup.3. The step (K) corresponds to the operation of the catalytic test that is performed by feeding the mixture of oil and hydrogen to the reactor in ascending mode (descending mode for bench scale). The composition and characteristics of feedstocks for micro and bench scales are those presented in Table 2. The feed to the reactor is a 50/50 wt % mixture of heavy crude and hydrodesulfurized diesel. The operating conditions in stage (K) are as follows: temperature of 380 C., pressure of 5.4 MPa, hydrogen/hydrocarbon ratio of 356 m.sup.3/m.sup.3, and LHSV of 1.0 h.sup.1. In stage L the reaction takes place during 120 h and during this time samples of product are taken every 12 h. Finally, in stage (M), analysis of the products from the reactor is performed.

(16) TABLE-US-00002 TABLE 2 Properties of typical heavy hydrocarbon oil Bench-scale-Feed Micro-plant Feed Properties (Heavy crude oil) (Diluted feedstock) Elemental analysis C, wt. % 86.9 84.2 H, wt. % 5.3 8.8 N, wt. % 0.3 0.184 S, wt. % 3.52 2.21 Metal, wppm Ni 49.5 26.21 V 273.0 124.78 (Ni + V) 322.5 150.99 Ca 11.26 5.0 Mg 2.04 1.01 Na 44.83 21.2 K 20.25 10.2 Fe 2.16 1.02 Asphaltene, wt. % (n-C.sub.7 insol.) 12.7 8.43 Physical properties Density, 20/4 C. 0.9251 0.88 Pour point, C. 30 15 Ramscarbon, wt. % 10.87 5.45 API gravity 21.31 37.09 Viscosity, g/cm s at 50 C. 3.08 at 100 C. 9.45

(17) The selected conditions for the evaluation of catalysts at micro plant and bench scale are those presented in Table 3. At bench scale level the operating conditions for evaluation of the catalysts are more severe than at micro-plant level, the run time was increased to 1000 h and the amounts of catalyst and inert material were 100 and 50 mL respectively.

(18) TABLE-US-00003 TABLE 3 Reactor specifications and reaction conditions for fixed-bed integral reactors Bench scale Conditions Micro-plant plant Reactor Specification Reactor Length, in 22.2 55 Reactor inner diameter, in 0.51 1.0 Reactor outer diameter, in 0.98 1.5 Reactor material (inox) SS-316 SS-316 Reaction Conditions Temperature, C. 380 400 Pressure, MPa 5.4 7.0 Hydrogen flow, l/h 4.6 90 Flow of heavy crude, mL/h 10 100 LHSV, h.sup.1 1.0 1.0 Hydrogen/Oil ratio, m.sup.3/m.sup.3 356 891.0 Mode of operation Up-flow Down flow Time-on-stream, h 120 200 Catalyst volume, mL (g) 10 (8.5) 100 (85.0) Extrudate diameter, mm 2.5 2.5 Extrudate length, mm 5-7 5-7 Feed composition tested Pure heavy crude Diluted feedstock

EXAMPLES

(19) The following examples are provided to illustrate the behavior of the catalyst of the present invention and its use in hydroprocessing of heavy crude oil and residua. These examples should not be considered as limitations of the invention, but should merely teach how to make the appropriate support, catalyst and their evaluation, reflecting the present invention. The reactor had a fixed bed of a particulate supported transitions metal hydroprocessing catalyst. The reactor was run at a total pressure of 5.4-7 MPa. The liquid weight throughput based on catalyst volume was 1 h.sup.1, and the hydrogen throughput was equivalent to 891 m.sup.3/m.sup.3.

Example 1

(20) A support hydroprocessing catalyst containing the reference aluminas from Table 1 was prepared by the following procedure. The dried 50 parts of catapal C1 alumina (Catapal C1 from Condea) and 50 parts pseudoboehmite alumina (Catapal 200 from Condea) were well mixed in equal proportion considering 25% moisture in both samples. To the mix, diluted HNO.sub.3 acid and sufficient amount of de-ionized water were added to form an extrudable paste (3-5 wt % HNO.sub.3 to the total powders). These weights are on 100% solids basis. The paste was extruded in 1/16 cylinder, and dried at 100-120 C. overnight. The dried extrudates were calcined at 500-550 C. for 4 hours with purging of excess dry air to obtain a gamma alumina support, and cooled down to room temperature.

(21) Impregnation of Co and Mo was done using a solution containing ammonium heptamolybdate and cobalt nitrate to the target metal loadings of 2.2 wt % CoO and 10 wt % MoO.sub.3 in the finished catalyst. The total volume of the solution matched the 100% water pore volume of the base extrudate sample (incipient wetness method). The metal solution was added to the support extrudates gradually while tumbling the extrudates. When the solution addition was complete, the soaked extrudates were aged overnight. Then the extrudates were dried at 120 C. for 12 h. The dried extrudates were calcined at 450 C. for 4 hours with purging excess dry air, and cooled down to room temperature. This catalyst is designated Catalyst 1 (Cat-1) and its physical properties are summarized in Table 1 where it is observed that catalyst contains mesoporous material.

(22) The catalyst of the present invention was loaded to a reactor and used as first-stage hydrodemetallization catalyst. The run was carried out in a bench-scale test unit having automatic controls for pressure, flow of reactants, and temperature. The reactor specifications are reported in the Table 3. During the reaction the reactor temperatures were controlled at different reactor heights through outside as well as inside thermo-well extended up through the center of the reactor. The hydrocarbon feedstock was fed to the unit by means of a LDC pump, a positive-displacement pump. The activity products of the run were obtained from the product receiver and were analyzed for relevant analysis. Catalyst activities for HDS, HDN, HDM and HDAs are shown in FIG. 3. These activities were slightly decreased with time-on-stream almost at similar magnitude. as shown in FIG. 3.

Example 2

(23) Catalyst 2, a CoMo catalyst containing alumina of the invention, was prepared using a procedure similar to Catalyst 1. For Catalyst 2, catapal 200 alumina of the invention from Example 1 was used to prepare the base extrudates. This catalyst is named Catalyst 2 (Cat-2) and its physical properties are summarized in Table 1. The texturales property of the catalyst (Cat-2) is shown in Table 1 where it is observed that catalyst contains mesoporous material.

(24) Catalyst activities for HDS, HDM and HDAs were slightly higher than HDN. These activities were decreased with time-on-stream almost at similar magnitude as shown in FIG. 4.

Example 3

(25) Catalyst 3, a CoMo catalyst containing alumina of the invention, was prepared using a procedure similar to Catalyst 1. For Catalyst 3, 50 parts alumina (Pural SB, from Condea) of the invention from example 1 and 50 parts pural TH alumina (Pural TH 100, from Sasol) were used to prepare the base extrudates. This catalyst is designated Catalyst 3 (Cat-3) and its physical properties are summarized in Table 1. The textural properties of the catalyst (Cat-2) are shown in Table 1 where it is observed that the catalyst contains mesoporous material.

(26) The catalyst showed almost similar activity for HDS, HDM and HDAs. These activities decreased with time-on-stream almost at similar magnitude as shown in FIG. 5.

Example 4 (Comparison Between the Three Catalysts)

(27) The catalysts activities were compared for three different catalysts after 120 h time-on-stream as shown in FIG. 6. The activity corresponds to the pore diameter as well as the balance between the pore diameter and dispersion of catalytic sites.

Example 5

(28) Based on the balanced HDS and HDM activities results obtained in the evaluation of catalyst (Cat-1) at micro-plant scale after 120 hours of time-on-stream, this catalyst was evaluated at bench scale during 1000 h of time-on-stream. The reaction conditions were mentioned previously (Table 3). The behavior of Cat-1 at bench scale is presented in FIG. 7.

(29) The experiment of Example I is repeated with two changes. As base feedstock and a pure Maya crude is used having a sulfur content of 3.52%, a metals content of 322 ppm and a gravity of about 21.3. Results illustrating the effectiveness of the invention similar to those of Example I are observed.

(30) FIG. 7 shows the results of activity and stability of catalyst (Cat-1) of the present invention evaluated at bench scale. The formulation of Cat-1 exhibited the best activity in the micro plant tests; therefore, it was decided to evaluate this catalyst at bench scale, using a feedstock containing large amount of sulfur, nitrogen and metals. It is observed that catalyst presents constant stable behavior after 100 h and onwards along with time-on-stream of the test, maintaining an HDM conversion level of around 30%. In the same figure the behavior of catalyst (Cat-1) in the HDS (40%), HDN (15%), and HDAs (28%) reactions are also observed. The HDM and HDAs reactions presented the same stability maintaining a conversion of around 30% from 150 h up to 1000 h.

(31) Apart from the above conversion the hydrotreated product oil improved API gravity by 6-8 degree along with low metal and sulfur content. Such kind of feedstock can be directly used for hydrocracking or fluid catalytic cracking. During the HDM, catalyst retains Ni and V sulfides as shown in FIG. 8.