METHOD OF OPERATING AN EBULLATED BED PROCESS TO REDUCE SEDIMENT YIELD

Abstract

An improved method of operating a conventional ebullated bed process for the hydroconversion of heavy hydrocarbon feedstocks so as to provide for low or reduced sediment content in the conversion product without the loss of hydrodesulfurization function.

Claims

1. A method of operating an ebullated bed process for the hydroconversion of a heavy hydrocarbon feedstock, wherein said method comprises: providing an ebullated bed reactor system, comprising an ebullated bed reactor vessel that defines a reactor volume within which is an ebullated bed reaction zone defined by a catalyst bed comprising first shaped hydroprocessing catalyst particles having a first geometry providing for a first ratio of the cross section perimeter-to-cross sectional area that is less than 5 mm.sup.−1, and wherein said reactor volume further includes an upper zone above said ebullated bed reaction zone and a lower zone below said ebullated bed reaction zone; introducing said heavy hydrocarbon feedstock into said ebullated bed reaction zone, which is operated under hydroconversion reaction conditions; removing a portion of said first shaped hydroprocessing catalyst particles from said catalyst bed; adding to said catalyst bed an incremental amount of a second shaped hydroprocessing catalyst particles having a second geometry providing for a second ratio of the cross section perimeter-to-cross sectional area that is at least 5 mm.sup.−1; and yielding from said reactor volume a heavy hydrocarbon conversion product having a reduced sediment content.

2. The method of claim 1, wherein said first shaped hydroprocessing catalyst particles comprise an inorganic oxide powder in an amount in the range of from about 75 wt. % to 96 wt. %, a molybdenum compound in an amount in the range of from 3 wt. % to 15 wt. %, and a nickel compound in an amount in the range of from 0.5 wt. % to 6 wt. %, wherein each wt. % is based on the total weight of said first shaped hydroprocessing catalyst particle and the metal as an oxide regardless of its actual form, wherein said second shaped hydroprocessing catalyst particles comprise an inorganic oxide powder in an amount in the range of from about 75 wt. % to 96 wt. %, a molybdenum compound in an amount in the range of from 3 wt. % to 15 wt. %, and a nickel compound in an amount in the range of from 0.5 wt. % to 6 wt. %, wherein each wt. % is based on the total weight of said first shaped hydroprocessing catalyst particle and the metal as an oxide regardless of its actual form.

3. The method of claim 2, wherein said second ratio is in the range of from 5 mm.sup.−1 to 10 mm.sup.−1.

4. The method of claim 2, wherein said second ratio is in the range of from 5.5 mm.sup.−1 to 9 mm.sup.−1.

5. The method of claim 4, wherein said hydroconversion reaction conditions include a contacting temperature in the range of from 316° C. (600° F.) to 538° C. (1000° F.), a contacting pressure in the range of from 500 psia to 6,000 psia, a hydrogen-to-oil ratio in the range of from 500 scf/bbl to 10,000 scf/bbl, and liquid hourly space velocity (LHSV) in the range of from 0.1 hr.sup.−1 to 5 hr.sup.−1.

6. The method of claim 5, wherein said second geometry is selected from the group of configurations consisting of a circular cross section and polylobal cross sections, including trilobal cross sections.

7. A method of operating an ebullated bed process for the hydroconversion of a heavy hydrocarbon feedstock, wherein said method comprises: providing an ebullated bed reactor system designed for the use of first shaped hydroprocessing catalyst particles having a first geometry providing for a first ratio of the cross section perimeter-to-cross sectional area that is less than 5 mm.sup.−1 in a catalyst bed defining an ebullated bed reaction zone contained within a reactor volume defined by an ebullated bed reactor vessel, wherein said reactor volume includes an upper zone above said ebullated bed reaction zone and a lower zone below said ebullated bed reaction zone; introducing said heavy hydrocarbon feedstock into said ebullated bed reaction zone, which is operated under hydroconversion reaction conditions; introducing into said reactor volume second shaped hydroprocessing catalyst particles having a second geometry providing for a second ratio of the cross section perimeter-to-cross sectional area that is at least 5 mm.sup.−1 to thereby form said ebullated bed reaction zone; and yielding from said reactor volume a heavy hydrocarbon conversion product having a low sediment content.

8. The method of claim 7, wherein said first shaped hydroprocessing catalyst particles comprise an inorganic oxide powder in an amount in the range of from about 75 wt. % to 96 wt. %, a molybdenum compound in an amount in the range of from 3 wt. % to 15 wt. %, and a nickel compound in an amount in the range of from 0.5 wt. % to 6 wt. %, wherein each wt. % is based on the total weight of said first shaped hydroprocessing catalyst particle and the metal as an oxide regardless of its actual form, wherein said second shaped hydroprocessing catalyst particles comprise an inorganic oxide powder in an amount in the range of from about 75 wt. % to 96 wt. %, a molybdenum compound in an amount in the range of from 3 wt. % to 15 wt. %, and a nickel compound in an amount in the range of from 0.5 wt. % to 6 wt. %, wherein each wt. % is based on the total weight of said first shaped hydroprocessing catalyst particle and the metal as an oxide regardless of its actual form.

9. The method of claim 8, wherein said second ratio is in the range of from 5 mm.sup.−1 to 10 mm.sup.−1.

10. The method of claim 8, wherein said second ratio is in the range of from 5.5 mm.sup.−1 to 9 mm.sup.−1.

11. The method of claim 10, wherein said hydroconversion reaction conditions include a contacting temperature in the range of from 316° C. (600° F.) to 538° C. (1000° F.), a contacting pressure in the range of from 500 psia to 6,000 psia, a hydrogen-to-oil ratio in the range of from 500 scf/bbl to 10,000 scf/bbl, and liquid hourly space velocity (LHSV) in the range of from 0.1 hr.sup.−1 to 5 hr.sup.−1.

12. The method of claim 11, wherein said second geometry is selected from the group of configurations consisting of a circular cross section and polylobal cross sections, including trilobal cross sections.

Description

EXAMPLE 1

[0050] This Example 1 describes the preparation of a cylindrically shaped, co-mulled comparison Catalyst A and a trilobe shaped, co-mulled Catalyst B. Also presented are various of the properties of these catalysts.

[0051] A co-mulled mixture was prepared by mulling for 35=Mites 100 parts pseudo-boehmite powder, 2.25 parts of nitric acid, 22.3 parts of catalyst fines, 10.5 parts of nickel nitrate flakes, 6.8 parts of ammonium di-molybdate crystals, and 122.6 parts of water. An aliquot portion of the co-mulled mixture was then extruded through cylindrical extrusion holes, and an aliquot portion of the co-mulled mixture was extruded through trilobe extrusion holes. The geometric characteristics of the particles of the two catalysts are presented in Table 1.

[0052] The extrudates were separately dried at 121° C. (250° IF) for 4 hours in an oven followed by calcination at 778° C. (1465° F.) for an hour in a static furnace to yield Catalyst A and Catalyst B.

[0053] Selected physical properties of the two catalysts are given in Table 1. Note that the catalysts were prepared by a single-step method, i.e., co-mulling, and have pore structures that include macropores.

TABLE-US-00001 TABLE 1 Properties of the Catalyst A and Catalyst B Catalyst A Catalyst B Pellet diameter, mm 0.98 0.91 Pellet shape Cylinder Trilobe Average pellet length, mm 3 3 Pellet cross section perimeter/area 4.08 6.50 Pellet surface/volume 4.75 7.17 Total PV, cc/g 0.812 0.807 MPD, A 100 102 Vol >350A, cc/g 0.142 0.141 Mo, wt % 6.6 6.6 Ni, wt % 2.7 2.7 P, wt % 0.5 0.5

EXAMPLE 2

[0054] This Example 2 describes the conditions of the performance testing of Catalyst A and Catalyst B and presents the test results of the performance testing.

[0055] The catalysts were tested in a two-stage CSTR pilot plant. Feed properties are summarized in Table 2 and process conditions are presented in Table 3.

TABLE-US-00002 TABLE 2 Properties of the feed used to evaluate the catalysts 1050 F.+, wt % 76.43 SULFUR, wt % 3.058 MCR, wt % 19.1 NICKEL, wppm 67 VANDIUM, wppm 264 FEED DENSITY, g/ml 1.0367 n-C7 Insolubles, Wt % 8.0 n-C5 Insolubles, Wt % 12.6

TABLE-US-00003 TABLE 3 Processes conditions used to evaluate the catalysts Catalyst LHSV, hr.sup.−1 0.22 Total pressure, psia 2310 H2/Oil ratio, scft/bbl 2750 Temperature, ° F. 775

TABLE-US-00004 TABLE 4 Relative performance of Catalyst A and Catalyst B Catalyst Catalyst A Catalyst B 1050 F. conversion base 100 950 F.+ conversion base 100 Relative 660 F..sup.+ Sediments base 43% of base HDS activity base 98% of base

[0056] While the results presented in Table 4 show that the trilobe-shaped catalyst, having a large ratio of cross section perimeter-to-cross sectional area of greater than 5 mm.sup.−1 (i.e., 6.5 mm.sup.−1), exhibits essentially the same desulfurization activity than that of the cylinder-shaped catalyst, having a small ratio of cross section perimeter-to-cross sectional area of less than 5 mm.sup.−1 (i.e., 4.08 mm.sup.−1), what is more significant, and unexpected, is that the trilobe-shaped catalyst provides material improvements in sediment yield. The sediment yield provided with the trilobe-shaped catalyst is 43% of the sediment yield provided with the cylindrical-shaped catalyst. The trilobe-shaped catalyst particle with its significantly higher ratio of cross section perimeter-to-cross sectional area than that of the cylindrical particle (i.e., 6.5 mm.sup.−1 versus 4.08 mm.sup.−1) contributes to the observed reduction in sediment yield.

EXAMPLE 3

[0057] This Example 3 describes the preparation of a large particle, impregnated comparison Catalyst C, having a geometry such that the value for its characteristic cross section perimeter-to-cross sectional area is small and that of a small particle, impregnated Catalyst ID having use in one embodiment of the invention and a geometry such that the value for its characteristic cross section perimeter-to-cross sectional area is relatively large.

[0058] An extrudable alumina paste or mixture was prepared by combining 200 parts of alumina powder, 1 part of nitric acid, and 233 parts of water. A portion of the mixture was then extruded through cylindrical extrusion holes and a portion of the mixture was extruded through trilobe extrusion holes. The extrudates were dried at 121° C. (250° F.) for 4 hours in an oven and then calcined at 677° C. (1250° F.) for an hour in a static furnace. The resulting, alumina supports (comprising, consisting essentially of, or consisting of alumina) were then impregnated with a portion of an aqueous solution containing, molybdenum, nickel and phosphorus, in amounts so as to provide catalysts with the metal loadings indicated in Table 1, dried at 121° C. (250° F.) for 4 hours, and calcined at 482° C. (900° F.) for an hour.

[0059] Selected properties for the resulting Catalyst C and Catalyst D are summarized in Table 5. It is noted that these catalysts contain insignificant macroporosity.

TABLE-US-00005 TABLE 5 Catalyst C Catalyst D Pellet diameter, mm 0.93 0.97 Pellet shape Cylinder Trilobe Average pellet length, mm 3 3 Pellet cross section perimeter/area 4.35 7.73 Pellet surface/volume 5.01 8.40 Total PV, cc/g 0.73 0.73 MPD, A 105 105 Vol >350A, cc/g 0.02 0.02 Mo, wt % 6.5 6.5 Ni, wt % 1.8 1.8 P, wt % 0.7 0.7

EXAMPLE 4

[0060] This Example 4 describes the conditions of the performance testing of Catalyst C and Catalyst D and the results of the performance testing.

[0061] The catalysts were tested in a two-stage CSTR pilot plant. The properties of the feed are summarized in Table 6, and the process conditions are presented in Table 7.

TABLE-US-00006 TABLE 6 Properties of the feed used to evaluate the catalysts 1000 F.+, wt % 87.7 SULFUR, wt % 5.255 MCR, wt % 20.8 NICKEL, wppm 43 VANDIUM, wppm 130 FEED DENSITY, g/ml 1.0347 n-C7 Insolubles, Wt % 12.7 n-C5 Insolubles, Wt % 20.9

TABLE-US-00007 TABLE 7 Processes conditions used to evaluate the catalysts Catalyst LHSV, hr.sup.−1 0.55 Total pressure, psia 2250 H2/Oil ratio, scft/bbl 4090 Temperature, ° F. 795

[0062] The performance of Catalyst D relative to the performance of Catalyst C (Base) is summarized in Table 8.

TABLE-US-00008 TABLE 8 Relative performance of the catalysts Catalyst Catalyst C Catalyst D 1000 F. conversion, wt % Base 100 Relative 650 F..sup.+ Sediments, % of base Base 64 Relative 650 F.+ Sulfur, % of base Base 101 Relative 650 F.+ density, % of base Base 100

[0063] A review of the performance results presented in Table 8 shows that the conversion and desulfurization catalytic performance of Catalyst D are essentially the same as those of Catalyst C. Catalyst D, however, unexpectedly provides for a huge improvement in sediment yield as compared to Catalyst C. Catalyst D unexpectedly provides for 64% of the sediment yield that is provided by Catalyst C; thus, giving a 36% reduction in sediment yield over that provided by Catalyst C. These results show that the impregnated and low macroporosity ebullated bed catalyst particles, having a small particle size and specific geometry (i.e., cross section perimeter-to-cross sectional area ratio), unexpectedly affects sediment yield while having little or no impact on other of the catalytic properties, such as, conversion and desulfurization.