EBULLATED BED PROCESS FOR HIGH CONVERSION OF HEAVY HYDROCARBONS WITH A LOW SEDIMENT YIELD

Abstract

An ebullated bed process for the hydroconversion of heavy hydrocarbon feedstocks that provides for high conversion of the heavy hydrocarbon with a low sediment yield. The process uses for its catalyst bed an impregnated shaped ebullated bed catalyst having a low macroporosity and a geometry such that its characteristic cross section perimeter-to-cross sectional area is within a specifically defined range.

Claims

1. A process that uses an ebullated bed reactor system for the hydroconversion of a heavy hydrocarbon feedstock providing high conversion of said heavy hydrocarbon feedstock with a low sediment yield, wherein said process comprises: introducing said heavy hydrocarbon feedstock into 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; and wherein said ebullated bed reaction zone comprises a catalyst bed of small particle size, shaped hydroprocessing catalyst particles, wherein said shaped hydroprocessing catalyst particles comprise a calcined shaped alumina support impregnated with at least one active catalytic metal component, and wherein said shaped hydroprocessing catalyst particles are further characterized as having a low macroporosity and a geometry providing for a first ratio of the cross section perimeter-to-cross sectional area that is in the range of from 5 mm.sup.−1 to 8 mm.sup.−1; contacting under hydroconversion reaction conditions said heavy hydrocarbon feedstock with said shaped hydroprocessing catalyst particles within said ebullated bed reaction zone; and yielding from said upper zone a heavy hydrocarbon conversion product having a low sediment content.

2. A process as recited in claim 1, wherein said shaped hydroprocessing catalyst particles further include 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 shaped hydroprocessing catalyst particle and the metal as an oxide regardless of its actual form.

3. A process as recited in claim 2, 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-1 to 5 hr-1.

4. A process as recited in claim 3, wherein said geometry geometry is selected from the group of configurations consisting of a circular cross section and polylobal cross sections, including trilobal cross sections.

5. A process as recited in claim 4, wherein said cross section perimeter-to-cross sectional area that is in the range of from 5.5 mm.sup.−1 to 9 mm.sup.−1.

6. A process as recited in claim 5, wherein said low macroporosity is less than 9% of the total pore volume of pores having a diameter greater than 350 Å contained in said shaped hydroprocessing catalyst particles.

7. A process as recite in claim 5, wherein said low macroporosity is less than 2% of the total pore volume of pores having a diameter greater than 350 Å contained in said shaped hydroprocessing catalyst particles.

Description

EXAMPLE 1

[0061] This Example 1 describes the preparation of a large particle, impregnated comparison Catalyst A, 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 B 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.

[0062] 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.

[0063] Selected properties for the resulting Catalyst A and Catalyst B are summarized in Table 1. It is noted that these catalysts contain insignificant macroporosity.

TABLE-US-00002 TABLE 1 Catalyst A Catalyst B 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 > 350 A, 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 2

[0064] This Example 2 describes the conditions of the performance testing of Catalyst A and Catalyst B and the results of the performance testing.

[0065] The catalysts were tested in a 2-stage CSTR pilot plant. The properties of the feed are summarized in Table 2, and the process conditions are presented in Table 3.

TABLE-US-00003 TABLE 2 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-00004 TABLE 3 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

[0066] The performance of Catalyst B relative to the performance of Catalyst A (Base) summarized in Table 4.

TABLE-US-00005 TABLE 4 Relative performance of the catalysts Catalyst Catalyst A Catalyst B 1000 F. conversion, wt % Base 100 Relative 650 F..sup.+ Sediments, % of Base 64 base Relative 650 F.+ Sulfur, % of base Base 101 Relative 650 F.+ density, % of base Base 100

[0067] A review of the performance results presented in Table 4 show that the conversion and desulfurization catalytic performance of Catalyst B are essentially the same as those of Catalyst A. Catalyst B, however, unexpectedly provides for a huge improvement in sediment yield as compared to Catalyst A. Catalyst B unexpectedly provides for 64% of the sediment yield that is provided by Catalyst A; thus, giving a 36% reduction in sediment yield over that provided by Catalyst A. 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.