CN117813364A

CN117813364A - Efficient hydroprocessing and solvent deasphalting of heavy oils with sequential addition of dispersed catalyst

Info

Publication number: CN117813364A
Application number: CN202280056349.XA
Authority: CN
Inventors: 大卫·芒廷兰德; 布雷特·西尔弗曼
Original assignee: Hydrocarbon Technology and Innovation LLC
Current assignee: Hydrocarbon Technology and Innovation LLC
Priority date: 2021-08-17
Filing date: 2022-07-20
Publication date: 2024-04-02

Abstract

Combined hydrotreating and solvent deasphalting, and sequential addition of dispersed catalyst to process heavy oil without increasing equipment fouling. An example method includes: hydroprocessing heavy oils containing dispersed catalyst particles to produce upgraded heavy oils; solvent deasphalting the residuum portion of upgraded heavy oil to produce DAO and bitumen; and hydrotreating the deasphalted oil containing dispersed catalyst particles to produce an upgraded deasphalted oil. An example system includes: a mixer for mixing the catalyst precursor with heavy oil to form a conditioned feedstock; a heater that decomposes the catalyst precursor and forms dispersed catalyst particles in situ; a hydroprocessing reactor for hydroprocessing heavy oils to produce upgraded heavy oils; a solvent deasphalting system to separate DAO from asphalt; a mixer for mixing the catalyst precursor with the deasphalted oil to form a conditioned deasphalted oil; a heater that decomposes the catalyst precursor and forms dispersed catalyst particles in situ; and a hydrotreating reactor for hydrotreating the deasphalted oil to produce upgraded deasphalted oil.

Description

Efficient hydroprocessing and solvent deasphalting of heavy oils with sequential addition of dispersed catalyst

Technical Field

The present invention relates to methods and systems for heavy oil hydroprocessing (hydro-processing) and solvent deasphalting, including the use of sequentially added dispersed catalysts to improve efficiency.

Background

Conversion of heavy oils to useful end products involves extensive processing such as lowering the boiling point of the heavy oil, increasing the hydrogen to carbon ratio, and removing impurities such as metals, sulfur, nitrogen, and coke precursors. Examples of hydrocracking processes that use conventional heterogeneous catalysts to upgrade atmospheric tower bottoms include fixed bed hydrotreating, ebullated bed hydrotreating, and moving bed hydrotreating. Non-catalytic upgrading processes for upgrading vacuum bottoms include thermal cracking, such as delayed coking, flexicoking, visbreaking, and solvent extraction.

There is an increasing demand for more efficient use of low quality heavy oil feedstocks and extraction of valuable fuels therefrom. The low quality feedstock is characterized by the inclusion of relatively large amounts of hydrocarbons that boil nominally at 524 ℃ (975°f) or above. They also contain relatively high concentrations of asphaltenes, sulfur, nitrogen, and metals. The high boiling fractions derived from these low quality feedstocks typically have high molecular weights (typically represented by higher densities and viscosities) and/or low hydrogen to carbon ratios, which are associated with the presence of high concentrations of undesirable components, including asphaltenes and char. Asphaltenes and carbon residue are difficult to process, often leading to fouling of conventional catalysts and hydroprocessing equipment, as they can lead to coke and deposit formation.

Low quality heavy oil feedstocks contain high concentrations of asphaltenes, carbon residue, sulfur, nitrogen, and metals. Examples include heavy crude oil, oil sand bitumen, and residues left over from conventional refinery processes. Residuum (or "residuum") may refer to both atmospheric bottoms and vacuum bottoms. The atmospheric bottoms have a boiling point of at least 343 ℃ (650°f), but it is well known that the boiling point may vary from refinery to refinery, up to 380 ℃ (716°f). The vacuum bottoms (also referred to as "resid pitch" or "vacuum resid") have a boiling point of at least 524 ℃ (975°f), but it is well known that the boiling point may vary from refinery to refinery, up to 538 ℃ (1000°f) or even 565 ℃ (1050°f).

By comparison, an Arabian (Alberta) light crude oil contained about 9vol% vacuum residuum, while a Laidelmid heavy oil contained about 41vol% vacuum residuum, a Cold Lake asphalt contained about 50vol% vacuum residuum, and an Ababasca (Athabasca) asphalt contained about 51vol% vacuum residuum. As a further comparison, relatively light oils from North Sea (North Sea) regions, such as Dansk Blend, contain only about 15vol% vacuum residuum, while low quality european oils such as urale (uaral) contain more than 30vol% vacuum residuum, and oils such as Arab Medium are even higher, containing about 40vol% vacuum residuum.

In a given ebullated bed system, the production rate of conversion products is often limited by fouling. When an attempt is made to increase the production of conversion products beyond a practical limit, the fouling rate of heat exchangers and other process equipment becomes too fast, requiring more frequent shut-down for maintenance and cleaning. The refinery operator typically correlates the observed equipment fouling rate with a measure of sediment production and derives an operational sediment limit above which the refinery will avoid operating the ebullated bed hydrocracker. Thus, deposit generation and equipment fouling place practical upper limits on conversion and conversion product productivity. Such problems are exacerbated when using lower quality heavy oil feedstocks.

Some have used oil soluble catalysts and precursors as a source of additional catalyst metal to improve the performance and stability of ebullated bed reactors. U.S. patent No. 5,372,705 to Bhattacharya et al ("Bhattacharya") discloses a dual catalyst system comprising a porous supported catalyst in combination with an oil soluble catalyst (e.g., a metal salt of an aliphatic carboxylic acid). To increase the stability of ebullated bed reactors, bhattacharya requires the use of 5 to 20 wt% of an aromatic heavy oil additive, such as Heavy Cycle Gas Oil (HCGO). U.S. publication 2005/024781 A1 to Lott et al ("Lott") discloses a dual catalyst system comprising a porous supported catalyst and an oil soluble catalyst precursor that forms a colloidal or molecular catalyst in situ when properly mixed prior to decomposition. The Lott examples use 100-300ppm of colloidal or molecular molybdenum sulfide catalyst to achieve beneficial results. Lott teaches that colloidal or molecular catalysts preferentially bind to asphaltene molecules, which are difficult to hydrocrack using porous supported catalysts because size exclusion inhibits diffusion of large asphaltene molecules into the catalyst pores. Lott teaches that the incorporation of colloidal or molecular molybdenum sulfide catalysts with asphaltene molecules advantageously increases asphaltene conversion compared to porous supported catalysts alone.

Delayed coking and Solvent Deasphalting (SDA) are sometimes used to remove metals, asphaltenes, and other deposit formation and equipment fouling materials to produce "cleaner" distillates and liquids that are less likely to cause equipment fouling when further processed. Delayed coking can be used to extract certain amounts of distillable and liquid hydrocarbons from asphaltenes and other coke-forming materials, with the end products being distillates, liquid and petroleum coke, metals, precipitates and other non-distillable materials remaining in the coke. Solvent Deasphalting (SDA) can alternatively be used to remove metals, asphaltenes, and other insoluble materials, which ultimately form a waste asphalt product, to provide a deasphalted hydrocarbon feedstock that is less likely to form coke and deposits during hydroprocessing, which can reduce the frequency of equipment fouling and system cleaning.

However, delayed coking and SDA remove both upgradeable and non-upgradeable hydrocarbons, reducing the net yield of useful hydrocarbons. Delayed coking and SDA also remove catalytic metals that might otherwise help promote beneficial upgrading reactions. Thus, while delayed coking and SDA can be used to remove non-upgradeable hydrocarbons as well as metals and other impurities that may cause equipment fouling, they also produce waste products that cannot be further upgraded into useful hydrocarbon liquids. However, such finished products contain significant amounts of hydrocarbons that could otherwise be upgraded into useful fuels rather than being converted into low value coke or pitch finished products. They also contain catalytic metals that might otherwise promote beneficial upgrading reactions, rather than being removed as part of the coke or bitumen waste.

Thus, there remains a need to find a way to more effectively hydrotreat heavy oils and increase conversion without increasing equipment fouling by asphaltenes, metals, and other insoluble materials.

Disclosure of Invention

Disclosed herein are methods and systems for hydroprocessing heavy oils that combine solvent deasphalting with sequential addition of dispersed catalyst to more effectively hydrotreat the heavy oil and increase conversion without increasing equipment fouling by asphaltenes, metals, and other insoluble materials.

An example method of hydroprocessing heavy oils includes:

(1) Adding a first amount of catalyst precursor to the heavy oil and heating the heavy oil to form first dispersed metal sulfide catalyst particles in situ within the heavy oil;

(2) Hydrotreating a heavy oil containing first dispersed metal sulfide catalyst particles under hydrotreating conditions to produce a upgraded heavy oil containing converted hydrocarbons;

(3) Solvent deasphalting at least a portion of the upgraded heavy oil to produce deasphalted oil (DAO) and bitumen;

(4) Adding a second amount of catalyst precursor to the deasphalted oil and heating the deasphalted oil to form second dispersed metal sulfide catalyst particles in situ within the deasphalted oil; and

(5) Hydrotreating the deasphalted oil containing the second dispersed metal sulfide catalyst particles under hydrotreating conditions to produce a upgraded deasphalted oil containing converted hydrocarbons.

An example system for hydroprocessing heavy oils includes:

(1) One or more mixers for mixing a first amount of catalyst precursor with the heavy oil to form a conditioned heavy oil, which upon heating to a temperature above the decomposition temperature of the catalyst precursor forms first dispersed metal sulfide catalyst particles in situ within the heavy oil;

(2) One or more hydroprocessing reactors configured to hydroprocessing a heavy oil containing first dispersed metal sulfide catalyst particles under hydroprocessing conditions to produce a upgraded heavy oil containing converted hydrocarbons;

(3) A solvent deasphalting system configured to receive at least a portion of the upgraded heavy oil and solvent and to perform solvent deasphalting to produce deasphalted oil (DAO) and bitumen;

(4) One or more mixers for mixing a second amount of catalyst precursor with the deasphalted oil to form a conditioned deasphalted oil, which upon heating to a temperature above the decomposition temperature of the catalyst precursor forms second dispersed metal sulfide catalyst particles in situ within the deasphalted oil; and

(5) One or more hydroprocessing reactors configured to hydrotreat the deasphalted oil under hydroprocessing conditions to produce an upgraded deasphalted oil containing converted hydrocarbons.

In some embodiments, the heavy oil may be hydrotreated in one or more ebullated-bed reactors that utilize the first dispersed metal sulfide catalyst particles in combination with a heterogeneous ebullated-bed catalyst to produce upgraded heavy oil. Alternatively to or in addition to the ebullated bed reactor(s), the heavy oil may be hydrotreated in one or more slurry phase reactors that utilize the first dispersed metal sulfide catalyst particles alone or in combination with a conventional slurry catalyst and/or one or more fixed bed reactors that use the first dispersed metal sulfide catalyst particles in combination with a heterogeneous fixed bed catalyst.

In some embodiments, the deasphalted oil can be hydrotreated in one or more ebullated-bed reactors that utilize the second dispersed metal sulfide catalyst particles in combination with a heterogeneous ebullated-bed catalyst to produce an upgraded deasphalted oil. Alternatively or in addition to the ebullated bed reactor(s), the deasphalted oil may be hydrotreated in one or more slurry phase reactors using the second dispersed metal sulfide catalyst particles alone or in combination with a conventional slurry catalyst and/or one or more fixed bed reactors using the second dispersed metal sulfide catalyst particles in combination with a heterogeneous fixed bed catalyst.

The upgraded heavy oil may be separated into one or more lower boiling hydrocarbon fractions and one or more liquid hydrocarbon fractions, at least a portion of which is the feed to the solvent deasphalting, after the heavy oil is hydrotreated and before the solvent deasphalting. For example, upgraded heavy oil may be separated by one or more of thermal separation, atmospheric distillation, or reduced pressure distillation.

In some embodiments, solvent deasphalting comprises:

(1) Introducing at least a portion of the one or more liquid hydrocarbon fractions and a solvent (e.g., at least one paraffinic solvent) into an extractor unit;

(2) Removing a first stream comprising the deasphalted oil and a first portion of the solvent from the extractor unit and subjecting the first stream to flash separation followed by DAO vacuum stripping to produce the deasphalted oil and a first recovered solvent;

(3) Removing a second stream comprising bitumen and a second portion of the solvent from the extractor unit and subjecting the second stream to heating, flash separation and vacuum stripping of the bitumen to produce bitumen and a second recovered solvent; and

(4) At least a portion of the first recovered solvent and the second recovered solvent are recycled to the extractor, optionally with make-up solvent.

In some embodiments, the first amount of catalyst precursor added to the heavy oil is greater than the second amount of catalyst precursor added to the deasphalted oil. For example, the first amount of catalyst precursor added to the heavy oil may be at least about 25%, at least about 50%, at least about 75%, at least about 150%, at least about 300%, at least about 600%, at least about 1200%, or at least about 2000% more than the second amount of catalyst precursor added to the deasphalted oil.

In some embodiments, the heavy oil includes a higher concentration of dispersed metal sulfide catalyst particles during hydroprocessing than the deasphalted oil. For example, the concentration of the dispersed metal sulfide catalyst particles in the heavy oil during hydroprocessing may be at least about 5%, at least about 10%, at least about 15%, at least about 30%, at least about 50%, or at least about 100% higher than the concentration of the dispersed metal sulfide catalyst particles in the deasphalted oil during hydroprocessing.

As an example of how a combined hydroprocessing and deasphalting process and system with dispersed metal sulfide catalyst particles more effectively hydrotreats heavy oils, the total amount of catalyst precursor required to produce a given amount of conversion product using the combined hydroprocessing and solvent deasphalting disclosed herein is less than the total amount of catalyst precursor required to produce the same amount of conversion product without sequential addition of solvent deasphalting and dispersed metal sulfide catalyst particles (e.g., a hydroprocessing process or system that uses a dual catalyst system in an ebullated bed reactor but omits sequential addition of solvent deasphalting and dispersed metal sulfide catalyst particles). For example, the total amount of catalyst precursor required to produce a given amount of conversion product is reduced by at least about 2.5%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, or at least about 50% as compared to the total amount of catalyst precursor required to produce the same amount of conversion product in a hydrotreating process or system employing a dual catalyst system in an ebullated bed reactor, but omitting the sequential addition of solvent deasphalting and dispersed metal sulfide catalyst particles.

As another example of how an improved hydrotreating and solvent deasphalting process and system using a combination of dispersed metal sulfide catalyst particles more efficiently converts heavy oil into upgraded material, the total amount of bitumen produced by solvent deasphalting after hydrotreating heavy oil in the presence of dispersed metal sulfide catalyst particles is less than the total amount of bitumen produced by solvent deasphalting after hydrotreating heavy oil with the omission of dispersed metal sulfide catalyst particles. For example, the total amount of bitumen produced by solvent deasphalting after hydroprocessing a heavy oil in the presence of dispersed metal sulfide catalyst particles is reduced by at least about 2.5%, at least about 5%, at least about 10%, at least about 15%, or at least about 20% as compared to the total amount of bitumen produced by solvent deasphalting after hydroprocessing a heavy oil with dispersed metal sulfide catalyst particles.

It has been found that it may be advantageous to add or form a second amount of dispersed metal sulfide catalyst particles to the deasphalted oil when at least a portion of the first amount of dispersed metal sulfide catalyst particles remain in the asphalt after solvent deasphalting, i.e., when the deasphalted oil does not include all or a substantial portion of the first amount of dispersed metal sulfide catalyst particles contained in the hydrotreated upgraded heavy oil. It has been found that at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, or at least about 80% of the first dispersed metal sulfide catalyst particles remain in the asphalt after solvent deasphalting such that the deasphalted oil contains as much dispersed metal sulfide catalyst particles as is spent as a result of being removed from the asphalt. In some cases, substantially all of the first dispersed metal sulfide catalyst particles remain in the bitumen and substantially no particles remain in the deasphalted oil.

Because bitumen may contain a large amount of dispersed metal sulfide catalyst particles, in some embodiments it may be advantageous to recycle at least a portion of the bitumen by adding the bitumen to the heavy oil to be hydrotreated to provide additional dispersed metal sulfide catalyst particles in addition to the first dispersed metal sulfide catalyst particles. The amount of recycled asphalt can be selected such that the benefit of including more dispersed metal sulfide catalyst particles outweighs the damage caused by adding asphalt to heavy oil.

In contrast to hydroprocessing heavy oils using a dual catalyst system comprising a heterogeneous catalyst and dispersed metal sulfide catalyst particles in an ebullated-bed reactor, but omitting solvent deasphalting, the disclosed method and system for combining hydroprocessing of heavy oils and deasphalted oils with solvent deasphalting using dispersed metal sulfide catalyst particles allows the ebullated-bed reactor to operate at a higher overall severity than without solvent deasphalting.

For example, the disclosed methods and systems can include increasing the operating temperature of one or more ebullated-bed reactors by at least 2.5 ℃, at least 5 ℃, at least 7.5 ℃, or at least 10 ℃ as compared to hydroprocessing without solvent deasphalting and sequential addition of dispersed metal sulfide catalyst particles.

Additionally or alternatively, the disclosed methods and systems can include increasing the throughput of heavy oil by at least 2.5%, at least 5%, at least 10%, or at least 20% as compared to hydroprocessing without solvent deasphalting and sequential addition of dispersed metal sulfide catalyst particles.

Additionally or alternatively, the disclosed methods and systems can increase the conversion of heavy oil by at least 2.5%, at least 5%, at least 7.5%, at least 10%, or at least 15% as compared to hydroprocessing without solvent deasphalting and sequential addition of dispersed metal sulfide catalyst particles.

The disclosed methods and systems for combining hydrotreated heavy oils with solvent deasphalting and sequential addition of dispersed metal sulfide catalyst can reduce equipment fouling rates as compared to hydrotreated heavy oils using a dual catalyst system comprising heterogeneous catalyst and dispersed metal sulfide catalyst particles in an ebullated bed reactor, but omitting solvent deasphalting. In some embodiments, the disclosed methods and systems can reduce the rate of fouling of a plant by at least 5%, at least 10%, at least 15%, or at least 20% as compared to fouling of a plant using the same catalyst system at the same overall yield of conversion product, but omitting solvent deasphalting.

The rate of fouling of the equipment may be measured by at least one of the following methods: (i) the desired heat exchanger cleaning frequency; (ii) switching to a frequency of the backup heat exchanger; (iii) frequency of filter replacement; (iv) the frequency of filter (applicator) cleaning or replacement; (v) A rate of decrease in the surface temperature of a device comprising a device selected from the group consisting of a heat exchanger, a separator, or a distillation column; (vi) the rate of rise of furnace tube metal temperature; (vii) The calculated rate of increase of the fouling resistance coefficient of the heat exchanger and the furnace; (viii) a rate of increase in heat exchanger pressure differential; (ix) the frequency of cleaning the atmospheric and/or vacuum distillation columns; or (x) the frequency of maintenance turnarounds.

In some embodiments, the dispersed metal sulfide catalyst particles are less than 1 μm in size, or less than about 500nm in size, or less than about 250nm in size, or less than about 100nm in size, or less than about 50nm in size, or less than about 25nm in size, or less than about 10nm in size, or less than about 5nm in size.

In some embodiments, the dispersed metal sulfide catalyst particles may be formed in situ within the heavy oil from the catalyst precursor. For example, the dispersed metal sulfide catalyst particles may be formed by mixing the catalyst precursor into the entire heavy oil or deasphalted oil prior to thermal decomposition of the catalyst precursor and in situ formation of the active metal sulfide catalyst particles.

As a further example, embodiments may include mixing a catalyst precursor with a diluted hydrocarbon to form a diluted precursor mixture, then mixing the diluted precursor mixture with a heavy oil to form a conditioned heavy oil, and heating the conditioned heavy oil to decompose the catalyst precursor and form dispersed metal sulfide catalyst particles in situ in the heavy oil.

Similarly, embodiments may include mixing a catalyst precursor with a diluted hydrocarbon to form a diluted precursor mixture, then mixing the diluted precursor mixture with a deasphalted oil to form a conditioned deasphalted oil, and heating the conditioned deasphalted oil to decompose the catalyst precursor and form dispersed metal sulfide catalyst particles in situ in the deasphalted oil.

These and other advantages and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

Drawings

To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical examples of the invention and are therefore not to be considered limiting of its scope. The present invention will be described and explained in greater detail and with reference to the drawings, wherein:

FIG. 1 schematically illustrates a combined hydroprocessing and solvent deasphalting system for treating heavy oil feedstock;

FIG. 2 schematically illustrates an ebullated-bed reactor and separator unit for separating volatile and non-volatile materials, which may be used to hydrotreat heavy oil or deasphalted oil;

FIG. 3 schematically illustrates an ebullated-bed reactor and separator unit for separating volatile and non-volatile materials, which may be used to hydrotreat heavy oil or deasphalted oil;

FIG. 4 depicts a hypothetical asphaltene molecular structure;

FIG. 5 schematically illustrates a deasphalting system for separating asphalt from residuum material to produce deasphalted oil;

FIG. 6 schematically illustrates an exemplary combined hydroprocessing and solvent deasphalting system in which dispersed metal sulfide catalyst particles are added sequentially or formed in situ;

FIG. 7 schematically illustrates an exemplary ebullated-bed hydroprocessing system that includes a plurality of ebullated-bed reactors, with an interstage separator and a deasphalting unit interposed between the second and third ebullated-bed reactors, that optionally recirculates bitumen containing residual dispersed catalyst;

FIG. 8 schematically illustrates an exemplary ebullated bed hydroprocessing system that uses a dual catalyst system that can be used for hydroprocessing heavy oils or deasphalted oils;

FIG. 9 schematically illustrates a pilot scale ebullated bed hydroprocessing system configured for use with a heterogeneous catalyst by itself or a dual catalyst system comprising a heterogeneous catalyst and dispersed metal sulfide catalyst particles, which can be used to hydrotreat heavy oil or deasphalted oil and collect useful data;

FIG. 10 is a flow chart illustrating an exemplary method of hydrotreating heavy oil using dispersed metal sulfide catalyst particles and solvent deasphalting, wherein catalyst precursors are added sequentially to form a dispersed catalyst;

FIG. 11 is a flow chart illustrating an exemplary method for hydrotreating heavy oils using an ebullated bed reactor in combination with solvent deasphalting and using dispersed metal sulfide catalyst particles; and

fig. 12 is a flow chart illustrating an exemplary method of solvent deasphalting a hydrocarbon residuum to separate soluble deasphalted oil from insoluble asphalt prior to further hydrotreating the deasphalted oil with dispersed metal sulfide catalyst particles.

Detailed Description

I. Introduction and definition

Disclosed herein are methods and systems for hydroprocessing heavy oils that combine solvent deasphalting with sequential addition of dispersed catalyst to more effectively hydrotreat the heavy oil and increase the productivity of conversion products without increasing equipment fouling by asphaltenes, metals, and other insoluble materials.

The term "asphaltenes" refers to materials in heavy oil residuum that are generally insoluble in paraffinic solvents such as propane, butane, pentane, hexane, and heptane. Asphaltenes can include fused ring compound moieties bound together by heteroatoms such as sulfur, nitrogen, oxygen, and metals. Asphaltenes broadly include a variety of complex compounds having 80 to 1200 carbon atoms with a major molecular weight in the range of 1200 to 16900 as determined by solution techniques. About 80-90% of the metals in crude oil are contained in the asphaltene fraction, which, together with the higher concentration of nonmetallic heteroatoms, makes the asphaltene molecules more hydrophilic and less hydrophobic than the other hydrocarbons in the heavy oil residuum.

A hypothetical asphaltene molecular structure developed by Chevron A.G.bridge and its co-workers is shown in FIG. 4. Asphaltenes are generally defined in terms of the results of the insoluble analysis, and more than one definition of asphaltenes may be used. Specifically, the usual definition of asphaltenes is heptane insoluble minus toluene insoluble (i.e., asphaltenes are soluble in toluene; toluene insoluble deposits and residues are not counted for asphaltenes). Asphaltenes defined in this way can be referred to as "C ₇ Asphaltenes). Another definition is pentane insolubles minus toluene insolubles, commonly referred to as "C ₅ Asphaltenes). In the examples of the present invention, C is used ₇ Definition of asphaltenes, but C ₅ The definition of asphaltenes can be easily replaced.

The term "sediment" refers to solids formed in the liquid stream that can precipitate out in the equipment of the heavy oil hydroprocessing system. The sediment may include inorganic matter, coke, or insoluble asphaltenes precipitated after conversion. Deposits in petroleum products are typically measured using an IP-375 hot filtration test procedure for measuring total deposits in residual fuel oil, as disclosed as part of ISO 10307 and ASTM D4870. Other tests include IP-390 sediment test and Shell hot filtration test. The deposits are associated with oil components that tend to form solids during processing and handling. These solid forming components have a number of adverse effects in the hydroconversion process, including product quality degradation (e.g., bottoms quality) and operability problems associated with equipment fouling. It should be noted that although the strict definition of sediment is based on solids measurements in sediment tests, the term is generally used more loosely, referring to the solid forming components of the oil itself, which may not be present in the oil as actual solids, but which may form solids under certain conditions.

All crudes contain vacuum residuum components that have a characteristic "deposit formation tendency". Although the deposit formation tendencies of heavy oil feedstocks are not always quantifiable, some heavy oil feedstocks have more or less deposit formation tendencies. For example, russian crudes (e.g., ula crudes), south American crudes (e.g., venezuela crudes and Columbia crudes), and some middle or North American crudes (e.g., mexico crudes and certain Mexico bay crudes) have a significantly higher deposit formation tendency vacuum residuum component than ordinary crudes (e.g., west Texas medium crudes, alaska North slope crudes, many African crudes, north sea crudes, and most middle east crudes, including Arabian medium crudes, arabian heavy crudes, and bunny light crudes).

The term "scaling" refers to the formation of undesirable phases (foulants) that interfere with the process. The foulants are typically carbonaceous materials or solids that are deposited and accumulate within the process equipment. Equipment fouling can result in lost production due to equipment downtime, reduced equipment performance, increased energy consumption due to thermal insulation from fouling deposits in the heat exchanger or heater, increased equipment cleaning maintenance costs, reduced fractionator efficiency, and reduced reactivity of the heterogeneous catalyst.

The "equipment fouling rate" of a hydrocracking reactor may be measured by at least one of the following: (i) the desired heat exchanger cleaning frequency; (ii) switching to a frequency of the backup heat exchanger; (iii) frequency of filter replacement; (iv) the frequency of filter (applicator) cleaning or replacement; (v) A rate of decrease in the surface temperature of a device comprising a device selected from the group consisting of a heat exchanger, a separator, or a distillation column; (vi) the rate of rise of furnace tube metal temperature; (vii) The rate of increase of the calculated fouling resistance coefficient of the heat exchanger and the furnace; (viii) a rate of increase in heat exchanger pressure differential; (ix) the frequency of cleaning the atmospheric and/or vacuum distillation columns; or (x) the frequency of maintenance turnarounds.

The terms "heavy oil" and "heavy oil feedstock" refer to heavy crude oil, oil sand bitumen, barrel bottoms (bottom of the barrel) left over in the refinery process, and resid (e.g., visbroken bottoms), as well as any other low quality material containing a significant amount of high boiling hydrocarbon fractions and/or including significant amounts of asphaltenes that deactivate heterogeneous catalysts and/or lead to the formation of coke precursors and deposits. Examples of heavy oils include, but are not limited to, laudensted (Lloydminster) heavy oils, cold Lake asphalt, athabasca (Athabasca) asphalt, atmospheric bottoms, vacuum bottoms, resid (or "resid"), resid asphalt, vacuum resid (e.g., urea VR, arabinon VR, athabasca VR, cold Lake VR, maya VR, and Chichimene VR), deasphalted liquids obtained by solvent deasphalting, asphaltene liquids obtained as a by-product of deasphalting, and non-volatile liquid fractions remaining after distillation, thermal separation, solvent extraction, etc. of crude oil, bitumen from tar sands, liquefied coal, oil shale, or coal tar feedstock. As a further example, an atmospheric bottoms (ATB) may have a nominal boiling point of at least 343 ℃ (650°f), but it is understood that the point of fractionation (cut point) may vary from refinery to refinery and may be as high as 380 ℃ (716°f). The vacuum bottoms may have a nominal boiling point of at least 524 ℃ (975°f), but it should be appreciated that the fractionation point may vary from refinery to refinery and may be as high as 538 ℃ (1000°f) or even 565 ℃ (1050°f).

The "quality" of heavy oil can be measured by at least one characteristic selected from, but not limited to: (i) boiling point; (ii) sulfur concentration; (iii) nitrogen concentration; (iv) metal concentration; (v) molecular weight; (vi) viscosity; (vii) hydrogen to carbon ratio; (viii) asphaltene content; and (ix) deposit formation tendency.

The "low quality heavy oil" and/or "low quality feedstock mixture" may have at least one low quality characteristic as compared to the initial heavy oil feedstock, selected from, but not limited to: (i) a higher boiling point; (ii) a higher sulfur concentration; (iii) a higher nitrogen concentration; (iv) a higher metal concentration; (v) Higher molecular weight (typically expressed by higher density and viscosity); (vi) higher viscosity; (vii) a lower hydrogen to carbon ratio; (viii) higher asphaltene content; and (ix) a greater deposit formation tendency.

The term "opportunity feedstock" refers to a lower quality heavy oil and lower quality heavy oil feedstock mixture that has at least one lower quality characteristic as compared to the original heavy oil feedstock. The market value (or price) of the opportunistic raw material is generally lower than the original raw material.

The terms "deasphalted oil", "DAO" and "deasphalted oil feedstock" refer to hydrocarbon materials that include residuum materials produced from heavy oil in one or more hydroprocessing reactors and one or more separators that have been subjected to solvent deasphalting to remove asphaltenes, metals, deposits, and other insoluble materials by solvent extraction. Deasphalted oil is the soluble fraction removed from the solvent, while asphalt is a solvent insoluble material. Different solvents may be used to "lift" DAO from the residuum material being processed. Lighter solvents (e.g., C3 and C4) lift lower and reject larger amounts of aromatics and resins, while heavier solvents (e.g., C5-C7) extract more aromatics and resins, thus higher lifts.

The terms "hydrocracking" and "hydroconversion" refer to processes in which the primary purpose is to reduce the boiling range of the heavy oil and in which a substantial portion of the heavy oil is converted to products having a boiling range less than that of the original feedstock. Hydrocracking or hydroconversion generally involves fragmentation of larger hydrocarbon molecules into smaller molecular fragments having a lower number of carbon atoms and a higher hydrogen to carbon ratio. The mechanism by which hydrocracking occurs typically involves the formation of hydrocarbon radicals during thermal cracking followed by capping of the radicals with hydrogen. The hydrogen atoms or groups that react with the hydrocarbon radicals during hydrocracking can be generated at or through active catalyst sites.

The term "hydrotreating" refers to a process whose primary purpose is to remove impurities such as sulfur, nitrogen, oxygen, halides, and trace metals from a feedstock and saturate and/or stabilize hydrocarbon radicals by reacting them with hydrogen rather than allowing them to react with themselves. The main purpose is not to change the boiling range of the feed. Hydrotreating is most often carried out using a fixed bed reactor, although other hydrotreating reactors may be used, examples being ebullated bed hydrotreaters and slurry phase hydrotreaters.

Of course, "hydrocracking" and "hydroconversion" may also involve removal of sulfur and nitrogen and olefin saturation from the feedstock, as well as other reactions typically associated with "hydrotreating". The terms "hydroprocessing" and "hydroconversion" shall refer broadly to "hydrocracking" and "hydrotreating" processes, which define both ends of a range, and all between ranges.

The term "hydrocracking reactor" shall refer to any vessel in which hydrocracking the feedstock (i.e., lowering the boiling range of the feedstock) in the presence of hydrogen and a hydrocracking catalyst is the primary purpose. The hydrocracking reactor is characterized by having one or more inlets for the introduction of heavy oil and hydrogen gas therein, an outlet from which upgraded feedstock or material is withdrawn, and sufficient thermal energy to promote the breakdown of the larger hydrocarbon molecules into smaller molecules, resulting in the formation of hydrocarbon radicals. Examples of hydrocracking reactors include, but are not limited to, slurry phase reactors (i.e., a two-phase gas-liquid system), ebullated bed reactors (i.e., a three-phase gas-liquid-solid system), and fixed bed reactors (i.e., a three-phase system that includes a liquid feed that flows slowly downward over a fixed bed of solid heterogeneous catalyst or upward through a fixed bed of solid heterogeneous catalyst, where hydrogen flows generally co-currently but possibly counter-currently to heavy oil).

The term "hydrocracking temperature" refers to the minimum temperature required to cause significant hydrocracking of the heavy oil feedstock. Generally, the hydrocracking temperature preferably falls within the range of about 399 ℃ (750°f) to about 460 ℃ (860°f), more preferably within the range of about 418 ℃ (785°f) to about 443 ℃ (830°f), and most preferably within the range of about 421 ℃ (790°f) to about 440 ℃ (825°f).

The term "gas-liquid slurry phase hydrocracking reactor" refers to a hydrotreating reactor comprising a continuous liquid phase and a gaseous dispersed phase which forms a "slurry" of gas bubbles within the liquid phase. The liquid phase typically comprises a hydrocarbon feedstock that may contain a low concentration of dispersed metal sulfide catalyst particles (which may appear as colloids or pseudo solutes), and the gas phase typically comprises hydrogen, hydrogen sulfide, and vaporized low boiling hydrocarbon products. The liquid phase may optionally comprise a hydrogen donating solvent.

The term "gas-liquid-solid three-phase slurry hydrocracking reactor" is used when solid catalysts are used with liquids and gases. The gas may contain hydrogen, hydrogen sulfide and vaporized low boiling hydrocarbon products. The term "slurry phase reactor" shall refer broadly to both types of reactors (e.g., those having dispersed metal sulfide catalyst particles, those having particulate catalyst of micron or larger size, and those including both).

The terms "solid heterogeneous catalyst", "heterogeneous catalyst" and "supported catalyst" refer to catalysts commonly used in ebullated bed and fixed bed hydroprocessing systems, including catalysts designed primarily for hydrocracking, hydroconversion, hydrodemetallization and/or hydroprocessing. Heterogeneous catalysts typically comprise a catalyst support structure having large surface areas and interconnected channels or pores and finely divided active catalyst particles, such as cobalt, nickel, tungsten and molybdenum sulfides, dispersed within the channels or pores. The pores of the support are typically of limited size to maintain the mechanical integrity of the heterogeneous catalyst and to prevent the decomposition and formation of excessive fines in the reactor. Heterogeneous catalysts can be made into cylindrical pellets, cylindrical extrudates, other shapes such as trilobes, rings, saddles, etc., or spherical solids.

The terms "dispersed metal sulfide catalyst particles" and "dispersed catalyst" shall refer to catalyst particles having a particle size of less than 1 μm (submicron), preferably less than about 500nm, or less than about 250nm, or less than about 100nm, or less than about 50nm, or less than about 25nm, or less than about 10nm, or less than about 5nm in diameter. The term "dispersed metal sulphide catalyst particles" may include molecular or molecular-scale dispersed catalyst compounds. The term "dispersed metal sulphide catalyst particles" generally does not include metal sulphide particles larger than 1 μm and agglomerates of metal sulphide particles.

The term "molecularly dispersed catalyst" refers to a catalyst compound that is substantially "dissolved" or "dissociated" from other catalyst compounds or molecules in a hydrocarbon feedstock or suitable diluent. It may comprise very small catalyst particles containing a small number of catalyst molecules (e.g., 15 or fewer molecules) linked together.

The terms "residual dispersed catalyst particles" and "residual dispersed metal sulfide catalyst particles" shall refer to catalyst particles that remain with the hydrocarbon product when transferred from one vessel to another (e.g., from a hydroprocessing reactor to a separator and/or other hydroprocessing reactor). After separation of the hydrocarbon product into distillate and residual liquid or bitumen, for example by flash separation, thermal separation, atmospheric distillation, vacuum distillation or vacuum stripping, residual dispersed metal sulphide catalyst particles may also remain in the liquid residual fraction or bitumen.

The term "modulated feedstock" refers to a hydrocarbon feedstock that: the catalyst precursor has incorporated therein and is thoroughly mixed such that upon decomposition of the catalyst precursor and formation of the active catalyst, the catalyst will comprise dispersed metal sulfide catalyst particles formed in situ within the feedstock. The conditioned feedstock includes conditioned heavy oil and conditioned deasphalted oil.

When used in reference to a feedstock or resulting material or product that is being or has been hydrotreated, the terms "upgraded" and "upgraded" refer to one or more of a reduction in the molecular weight of the feedstock, a reduction in the feedstock boiling range, a reduction in asphaltene concentration, a reduction in the concentration of hydrocarbon radicals, and/or a reduction in the amount of impurities (e.g., sulfur, nitrogen, oxygen, halides, and/or metals).

The term "severity" refers to the amount of energy introduced into the heavy oil during hydroprocessing and is related to the operating temperature of the hydroprocessing reactor (i.e., higher temperature is associated with higher severity and lower temperature is associated with lower severity at the same or similar throughput) and the duration or residence time. The increased severity typically increases the amount of conversion products (including desired products and undesired products) produced by the hydroprocessing reactor. Conversion and throughput can also affect severity. For example, as the temperature increases while the throughput remains unchanged, the conversion typically increases for a given feedstock. To maintain temperature while increasing throughput (i.e., increasing liquid hourly space velocity) and thereby reducing residence time of heavy oil in the reactor, more thermal energy must be added to the system to offset the cooling effect of feeding a greater amount of initially cooler heavy oil into the reactor per unit time.

Desirable conversion products include hydrocarbons having reduced molecular weight, boiling point, and specific gravity, which may include end products such as naphtha, diesel, jet fuel, kerosene, wax, fuel oil, and the like. Other desirable conversion products include high boiling hydrocarbons that can be further processed using conventional refining and/or distillation processes. The bottom product of sufficient quality to be used as a fuel oil is another example of a desired conversion product.

Undesirable conversion products include coke, deposits, metals, and other solid materials that can deposit on hydroprocessing equipment and cause fouling, such as internal components of the reactor, separators, filters, piping, columns, heat exchangers, and heterogeneous catalysts. The undesired conversion product may also refer to unconverted residuum remaining after distillation, such as atmospheric bottoms ("ATB") or vacuum bottoms ("VTB"), particularly residuum that is of too low a quality to be useful as fuel oil or other desired use. Minimizing undesirable conversion products reduces equipment fouling and downtime required to clean the equipment. Nevertheless, in order for downstream separation equipment to function properly and/or to provide a liquid transport medium for carrying coke, sediment, metals and other solid materials, there may be a desired amount of unconverted resid that may otherwise deposit and foul the equipment, but they may be carried away from the remaining resid.

In addition to temperature, "severity" may be related to one or both of "conversion" and "throughput. Whether increased severity relates to increased conversion and/or increased or decreased throughput may depend on the quality of the heavy oil feedstock and/or the mass balance of the overall hydroprocessing system. For example, where a greater amount of feed needs to be converted and/or provided to downstream equipment, an increased severity may primarily involve increased throughput without having to increase conversion fraction (fractional conversion). This may include the case where the residuum fractions (ATB and/or VTB) are sold as fuel oils, increasing conversion without increasing throughput may reduce the amount of that product. Where it is desired to increase the ratio of upgraded material to resid fraction, it may be desirable to primarily increase conversion without having to increase throughput. In the event of fluctuations in the quality of heavy oil introduced into the hydroprocessing reactor, it may be desirable to selectively increase or decrease one or both of conversion and throughput to maintain a desired ratio of upgraded material to resid fraction and/or a desired absolute amount of final product being produced.

The terms "conversion" and "conversion fraction (fractional conversion)" refer to the proportion of heavy oil converted to low boiling and/or low molecular weight materials, typically expressed as a percentage. The conversion is expressed as a percentage of the initial residuum content (i.e., the component having a boiling point greater than the defined residuum fractionation point) converted to a product having a boiling point less than the defined fractionation point. The definition of the residuum fractionation point can vary and can nominally include 524 ℃ (975°f), 538 ℃ (1000°f), 565 ℃ (1050°f), etc. It can be measured by distillation analysis of the feed and product streams to determine the concentration of components boiling above a defined fractionation point. The conversion fraction is expressed as (F-P)/F, where F is the amount of resid in the combined feed stream and P is the amount in the combined product stream, where the feed and product resid contents are defined based on the same fractionation point. The amount of resid is typically defined based on the mass of the components having boiling points greater than the defined fractionation point, but volumetric or molar definitions may also be used.

Asphaltene conversion may be different from the total conversion of heavy oil. For the purposes of this disclosure, a useful definition of asphaltene conversion is based on the relative amounts of asphaltenes in the fresh feedstock and upgraded product, and can be defined by the following formula, which yields a fractional portion of 0 to 1, convertible to a percentage by multiplication by 100:

conversion = [ Asph (fresh feed) -Asph (product) ]/Asph (fresh feed).

Asphaltene content in the recycle stream is an internal component of the process. Recycling build-up of asphaltenes can occur when the conversion of asphaltenes is generally too low compared to the conversion of heavy oil.

The term "throughput" refers to the amount (mass or volume) of feed material introduced into the hydroprocessing reactor per unit time. Throughput may be expressed in terms of volume, such as barrels per hour or day, or in terms of mass, such as metric tons per hour or day. In general use, throughput is defined as the mass or volumetric feed rate of only the heavy oil feedstock itself (e.g., vacuum bottoms, etc.). This definition generally excludes the amount of diluent or other components that may be added to or included in the total feed to the hydroconversion unit, although definitions including those other components may also be used.

The terms "space velocity" and "liquid hourly space velocity" relate to the throughput of a particular reactor or reactor size, but are normalized to remove the size (volume) of the reactor. Thus, a larger reactor may have twice the capacity of a half-volume size reactor, but the space velocity is the same. Thus, for a given reactor size, the increase in space velocity is generally proportional to the increase in throughput. Space velocity is inversely proportional to residence time of heavy oil in a reactor of a given reactor size.

The "rate of production of the conversion product" is an absolute rate expressed in terms of volume, such as barrels per hour or day, or in terms of mass, such as metric tons per hour or day. The "rate of production of conversion product" should not be confused with yield or efficiency, which is sometimes referred to as the "rate" by mistake (e.g., rate of production per unit feed rate or rate of production per unit conversion feed). It should be appreciated that the actual values of the initial production rate of the conversion product and the increased production rate of the conversion product are specific to a single production facility and depend on the capacity of that facility. Therefore, it is effective to compare the production rates of the related devices or facilities before and after the retrofit, but cannot be compared with different devices or facilities having different capacity.

Hydrotreating and deasphalting system

Fig. 1 schematically illustrates an embodiment of a combined hydrotreating and deasphalting system 100 for efficient upgrading of heavy oils. The system 100 includes a subsystem for hydroprocessing heavy oils, a subsystem for partially deasphalting residuum from conversion products of the hydroprocessing heavy oils to produce deasphalted oil, and a subsystem for hydroprocessing the deasphalted oil.

The subsystem for hydroprocessing heavy oils is configured to hydrotreat a heavy oil feedstock 102, to which a first portion 104a of a catalyst precursor 104 is added to form a conditioned feedstock 106, which feedstock 106 decomposes to release catalyst metals when heated above its decomposition temperature. The catalyst metal reacts with sulfur (e.g., hydrogen sulfide gas and/or organic sulfur compounds in the heavy oil feedstock 102) to form a first amount of dispersed metal sulfide catalyst particles in situ within the heavy oil feedstock 102. The conditioned feedstock may be preheated prior to being fed into the first hydroprocessing reactor 108a to form dispersed metal sulfide catalyst particles, or may be fed directly into the hydroprocessing reactor 108a, where the conditioned feedstock is raised to a hydroprocessing (e.g., hydrocracking) temperature that is above the decomposition temperature of the catalyst precursor. In either case, the dispersed metal sulfide catalyst particles are formed by thermal deposition and reaction with sulfur.

The first and second hydroprocessing reactors 108a, 108b can be any hydroprocessing reactors known in the art. In a preferred embodiment, the first and second reactors 108a, 108b are ebullated bed reactors that include common features of ebullated bed hydroprocessing reactors known in the heavy oil upgrading arts. Non-limiting examples include H-Oil and LC refining systems. Hydrogen (not shown) is introduced under pressure into the reactors 108a, 108b using known means. Heterogeneous ebullated bed catalysts known in the art can be used as solid supported catalysts that, together with dispersed metal sulfide catalyst particles, provide two forms of hydrotreating catalyst (i.e., a dual catalyst system). Heavy oil feedstock containing catalyst precursor and/or in situ formed dispersed metal sulfide catalyst particles is typically fed continuously to the first hydroprocessing reactor 108 a. The first and second hydroprocessing reactors 108a, 108b are operated at desired hydroprocessing conditions, including desired reactor severity based on temperature, conversion, and throughput.

A first stream of upgraded heavy oil 110a containing conversion products, dispersed metal sulfide catalyst particles, and hydrogen is removed from the first reactor 108a and fed to a second hydroprocessing (e.g., ebullated bed) reactor 108b, which second hydroprocessing reactor 108b can operate similarly to the first (e.g., ebullated bed) reactor 108 a. Because the ebullated bed catalyst remains in the first ebullated bed reactor 108a and is not carried with the upgraded heavy oil 110a to the second ebullated bed reactor 108b, the second ebullated bed reactor 108b will include a separate amount of ebullated bed catalyst. However, because the dispersed metal sulfide catalyst particles from the first reactor 108b are removed and carried in the upgraded heavy oil 110a fed to the second reactor 108b, it is generally not necessary to add additional catalyst precursor to form additional amounts of dispersed metal sulfide catalyst particles for the second reactor 108b (although this may be done if desired). An additional amount of make-up hydrogen may be fed to the second reactor 108b to at least partially compensate for the hydrogen consumed in the first reactor 108 a.

A second stream of upgraded heavy oil 110b containing other conversion products, dispersed metal sulfide catalyst particles, and hydrogen is removed from the second hydroprocessing reactor 108b and fed to a separator 112, a non-limiting example of which separator 112 is a thermal separator. A gaseous stream 114 of vaporized hydrocarbons and gases is removed from the top of separator 112 and a liquid stream 116 of hydrocarbons containing unconverted product is removed from the bottom of separator 112. The volatile hydrocarbon and gas stream 114 may be further processed downstream into a product 118.

The liquid hydrocarbon stream 116 containing unconverted product and residual dispersed metal sulfide catalyst particles is fed to a deasphalting system 120, which is schematically shown as a single vessel for simplicity, but in practice typically comprises a plurality of vessels, separators and flow lines, as further shown in fig. 5 below. A deasphalting solvent (not shown) is introduced into deasphalting system 120 to separate soluble hydrocarbons from insoluble materials such as asphaltenes, metals, and other insoluble materials, which are removed as bitumen stream 122, bitumen stream 122 can be discarded, recycled as part of the heavy oil feedstock used in the heavy oil hydroprocessing subsystem, for example, to provide additional amounts of dispersed metal sulfide catalyst particles, and/or further processed into product 134.

Stream 124 of deasphalted oil from deasphalting system 120 is fed to hydrotreating reactor 128 configured to hydrotreat the deasphalted oil. The deasphalted oil typically contains as much dispersed metal sulfide catalyst particles as is substantially consumed to the extent that the deasphalting system 120 has removed a majority of the remaining dispersed metal sulfide catalyst particles in the hydrocarbon stream 116. Thus, the second portion 104b of the catalyst precursor 104 is advantageously added to the deasphalted oil 124 prior to introduction into the hydroprocessing reactor 128 to form a second amount of dispersed metal sulfide catalyst particles in the stream of conditioned deasphalted oil 126.

The hydroprocessing reactor 128 may be similar to or different from the reactors 108a, 108b for hydroprocessing heavy oils. In some embodiments, the reactor 128 may be an ebullated bed reactor that utilizes a combination of heterogeneous catalyst and dispersed metal sulfide catalyst particles. Because the deasphalted oil contains a significantly reduced amount of asphaltenes, metals, and other foulants, the hydroprocessing reactor 128 can be configured to operate at significantly higher severity (e.g., one or more of higher temperature, conversion, and/or throughput) to increase or maximize efficiency. The significant reduction in asphaltenes in the deasphalted oil can also allow for the use of fewer catalyst precursors and smaller amounts of dispersed metal sulfide catalyst particles than the amount of dispersed metal sulfide catalyst particles in the reactors 108a, 108b for hydroprocessing heavy oils.

The concentration of the dispersed metal sulfide catalyst particles used in the reactors 108a, 108b for hydroprocessing the heavy oil is determined by the amount of the first amount 104a of catalyst precursor 104 added to the heavy oil feedstock 102, and in some cases, may be increased by optionally recycling a portion of the bitumen 122 produced by the deasphalting system 120 back to the heavy oil feedstock 102 and/or one or both of the reactors 108a, 108 b.

The concentration of the dispersed metal sulfide catalyst particles used in the hydrotreated deasphalted oil reactor 128 is determined by the amount of the second amount 104b of the catalyst precursor 104 added to the deasphalted oil 124, and the deasphalted oil 124 may contain residual supplemental dispersed metal sulfide catalyst particles that remain in the deasphalted oil 124 and are not removed in the asphalt 122.

In some embodiments, the concentration of the dispersed metal sulfide catalyst particles of the reactor for hydrotreating the deasphalted oil may be from about 2% to about 80%, or from about 3% to about 60%, or from about 4% to about 50%, or from about 5% to about 40%, or from about 6% to about 30% of the concentration of the dispersed metal sulfide catalyst particles of the reactor for hydrotreating the heavy oil.

Fig. 2 and 3 schematically illustrate ebullated bed hydroprocessing reactors 200, 300 that can be used to hydrotreat and deasphalt heavy oil in the combined processes and systems disclosed herein for hydrotreating and deasphalting heavy oil. Each of ebullated-bed hydroprocessing reactors 200, 300 can be operated at desired hydroprocessing conditions, including a desired reactor severity based on temperature, conversion, and throughput based on the type and quality of heavy oil or deasphalted oil being hydrotreated and the desired production rate of conversion products.

The hydrotreated feedstock may comprise any desired fossil fuel feedstock and/or fraction thereof including, but not limited to, one or more of heavy crude oil, oil sand bitumen, bottoms of barrel fractions (barrel fractions) of crude oil, atmospheric tower bottoms, vacuum tower bottoms, coal tar, liquefied coal and other residuum fractions, and deasphalted oil. Heavy oils and resids can contain significant proportions of high boiling hydrocarbons (i.e., nominally at or above 343 ℃ (650°f), more particularly nominally at or above about 524 ℃ (975°f)) and/or asphaltenes. Asphaltenes are complex hydrocarbon molecules that include relatively low hydrogen to carbon ratios, which are the result of a large number of fused aromatic and cyclic hydrocarbon rings with paraffinic side chains (see fig. 4). The sheets consisting of fused aromatic and cyclic hydrocarbon rings are bound together by heteroatoms such as sulfur or nitrogen and/or polymethylene bridges, thioether bonds, and vanadium and nickel complexes. The asphaltene fraction also contains higher levels of sulfur and nitrogen than the remainder of the crude oil or vacuum residuum, as well as higher concentrations of carbon forming compounds (i.e., compounds that form coke precursors and deposits).

FIG. 2 schematically illustrates an ebullated bed hydroprocessing reactor 200 developed by C-E Lumms for use in an LC-refinery hydrocracking system. Ebullated bed reactor 200 includes an inlet 206 near the bottom through which feedstock 202 and pressurized hydrogen 204 are introduced, and an outlet 208 at the top through which hydrotreated material 210 is withdrawn.

The ebullated bed reactor 200 further includes an expanded catalyst zone 212 containing a heterogeneous catalyst 214, which heterogeneous catalyst 214 is maintained in an expanded or fluidized state against gravity by upward movement of liquid hydrocarbons and gases (depicted schematically as bubbles 216) through the ebullated bed reactor 200. The lower end of the expansion catalyst zone 212 is defined by a distributor grid 218, which distributor grid 218 separates the expansion catalyst zone 212 from a lower heterogeneous catalyst-free zone 220 located below the distributor grid 218. The distributor grid 218 is configured to uniformly distribute the hydrogen and hydrocarbons in the reactor and prevent the heterogeneous catalyst 214 from falling under the force of gravity into the lower heterogeneous catalyst-free zone 220. The height of the upper end of the expanded catalyst zone 212 is such that the downward gravity equals or exceeds the upward force of the feedstock and gas moving upward through the reactor 200 as the heterogeneous catalyst 214 reaches a given level of expansion or separation. Above the expanded catalyst zone 212 is an upper heterogeneous catalyst free zone 222.

Hydrocarbons and other materials within ebullated-bed reactor 200 are continuously recycled from upper heterogeneous catalyst-free zone 222 to lower heterogeneous catalyst-free zone 220 via recycle passage 224, which recycle passage 224 is centrally located within ebullated-bed reactor 200 and is connected to ebullated pump 226 at the bottom of reactor 200. At the top of the recirculation channel 224 is a funnel-shaped recirculation cup 228 through which the hydrocarbons and other materials in the liquid are withdrawn from the upper heterogeneous catalyst free zone 222 through the recirculation cup 228. The material withdrawn downwardly through the recirculation channel 224 enters the lower catalyst free zone 220 and then upwardly through the distributor grid 218 and into the expanded catalyst zone 212 where it mixes with the newly added feedstock 202 and hydrogen 204 entering the ebullated bed reactor 200 through inlet 206. The continuous recirculation of the mixed material upwardly through ebullated bed reactor 200 advantageously maintains heterogeneous catalyst 214 in an expanded or fluidized state within expanded catalyst zone 212, minimizes channeling, controls the reaction rate, and distributes the heat released by the exothermic hydrogenation reaction to maintain the reactor temperature at a safe level.

Fresh heterogeneous catalyst 214 is periodically introduced into ebullated-bed reactor 200, such as into expanded catalyst zone 212, through catalyst inlet pipe 230, which catalyst inlet pipe 230 passes through the top of ebullated-bed reactor 200 and directly into expanded catalyst zone 212. Spent heterogeneous catalyst 214 is withdrawn from the expanded catalyst zone 212 through a catalyst withdrawal pipe 232, which catalyst withdrawal pipe 232 passes from the lower end of the expanded catalyst zone 212 through the distributor grid 218 and through the bottom of the reactor 200. It will be appreciated that the catalyst withdrawal line 232 cannot distinguish between fully spent catalyst, partially spent but active catalyst, and newly added catalyst, such that the randomly distributed heterogeneous catalyst 214 is typically withdrawn from the ebullated bed reactor 200 as "spent" catalyst.

The hydrotreated material 210 withdrawn from the outlet 208 of the ebullated-bed reactor 200 can be introduced into a separator 240 (e.g., a thermal separator, an interstage pressure differential separator, an atmospheric distillation column, or a vacuum distillation column). Separator 240 is configured to separate one or more volatile fractions (or distillates) 242 from a non-volatile fraction (or liquid) 244. Volatile fractions and gases 246 are removed at one location (e.g., the top) of the separator 204, and a non-volatile fraction 248 comprising non-volatile liquid hydrocarbons and solids is removed from another location (e.g., the bottom) of the separator 204.

Fig. 3 schematically illustrates an ebullated bed reactor 300 developed by Hydrocarbon Research Incorporated and currently licensed by Axens for use in an H-Oil hydrocracking system. Ebullated bed reactor 300 includes an inlet 306 through which feedstock 302 and pressurized hydrogen 304 are introduced, and an outlet 308 through which upgraded hydrocarbon material 310 is withdrawn.

The expanded catalyst zone 312, including the heterogeneous catalyst 314, is defined by a distributor grid plate 318 and an upper end 332, the distributor grid plate 318 separating the expanded catalyst zone 312 from a lower catalyst-free zone 330 below the distributor grid plate 318, the upper end 129 defining the approximate boundary between the expanded catalyst zone 312 and the upper catalyst-free zone 334. The dashed boundary line 336 schematically illustrates the general level of heterogeneous catalyst 314 when not in an expanded or fluidized state.

Hydrocarbons and other materials in ebullated bed reactor 300 are continuously recycled through recycle channel 338 which is connected to ebullated pump 340 located outside of reactor 300. Material is withdrawn from the upper catalyst free zone 334 through a funnel shaped recirculation cup 342. The recirculation cup 342 is helical in shape, which helps to separate hydrogen bubbles 316 from the recirculated material passing down through the recirculation channel 338 to prevent cavitation of the boiling pump 340. The recycle material enters the lower catalyst free zone 330 where it is mixed with fresh feed 302 and hydrogen 304 and the mixture passes upward through the distributor grid 318 and into the expanded catalyst zone 312. Fresh heterogeneous catalyst is introduced into expanded catalyst zone 312 through catalyst inlet pipe 344 and spent catalyst is withdrawn from expanded catalyst zone 312 through catalyst discharge pipe 346.

The main difference between the H-Oil ebullated-bed reactor 300 and the LC-refinery ebullated-bed reactor 200 is the location of the ebullated pump. The boiling pump 340 in the H-Oil reactor 300 is located outside the reaction chamber. The recycled feed material is introduced through a recycle port in the bottom of the reactor 300 having a distributor 346. The recirculation ports with the distributor 346 help to evenly distribute the material through the lower catalyst free zone 330.

Hydrotreated material 310 withdrawn from outlet 308 of ebullated-bed reactor 300 can be introduced into a separator 350 (e.g., a thermal separator, an interstage pressure differential separator, an atmospheric distillation column, or a vacuum distillation column). Separator 350 is configured to separate one or more volatile fractions (or distillates) 352 from a non-volatile fraction (or liquid) 354. Volatile fraction and gas 356 are removed at one location (e.g., the top) of separator 350, and a non-volatile fraction 358 comprising non-volatile liquid hydrocarbons and solids is removed from another location (e.g., the bottom) of separator 350.

Fig. 5 schematically illustrates a deasphalting system 500 that can be used to hydrotreat and deasphalt heavy oil in the combined method and system disclosed herein. The deasphalting system 500 includes an extractor unit 502 configured to receive and separate soluble hydrocarbons from asphaltenes and other insoluble materials in hydrocarbon residues by solvent extraction 502.

A hydrocarbon residuum (residuum) 504) (e.g., atmospheric or vacuum bottoms) is combined with a first extraction solvent stream 506a to form a mixed residuum-solvent stream 508 that is introduced into extractor unit 502. The solvent-soluble hydrocarbon materials in residuum 504 migrate to the top of extractor unit 502 where they are heated by steam 510 and removed as deasphalted oil (DAO)/solvent stream 512. Insoluble materials including asphaltenes, metals, at least a portion of the dispersed metal sulfide catalyst particles, sediment, and other solids (collectively, "pitch") settle to the bottom of the extractor unit 502. The second solvent stream 506b is added to the bottom of the extractor unit 502 where it is mixed with insoluble asphalt material to form an asphalt/solvent stream 514 that is removed from the bottom of the extractor unit 502. As described below, these two streams 512, 514 are further processed to remove solvent and produce a deasphalted oil stream 534 and an asphalt stream 564.

The (DAO)/solvent stream 512 is introduced into a series of flash separators 520a, 520b, 520c, followed by a vacuum stripper 530 to remove the solvent. (DAO)/solvent stream 512 is introduced into a first flash separator 520a that separates a first solvent stream 522a from a first concentrated DAO/solvent stream 524a, which first concentrated DAO/solvent stream 524a is sent to a first heat exchanger 526a to transfer heat from first solvent stream 522a to first concentrated DAO/solvent stream 524a. The first concentrated (DAO)/solvent stream 524a is introduced into a second flash separator 520b, the second flash separator 520b separates a second solvent stream 522b from the second concentrated DAO/solvent stream 524b, the second concentrated DAO/solvent stream 524b entering a second heat exchanger 526b to transfer heat from the second solvent stream 522b to the second concentrated DAO/solvent stream 524b. Second concentrated (DAO)/solvent stream 524b is introduced into third flash separator 520c, which separates third solvent stream 522c from third concentrated DAO/solvent stream 524 c. Solvent streams 522a, 522b, 522c are combined into a single solvent stream 522, which single solvent stream 522 is sent to solvent tank 540.

Third concentrated DAO/solvent stream 524c is introduced with steam 530 into DAO vacuum stripper 528, which separates wet solvent stream 532a from deasphalted oil (DAO) 534, which deasphalted oil (DAO) 534 can be further hydrotreated using a hydrotreating reactor and a dispersed metal sulfide catalyst as described herein. The wet solvent stream 532a is combined with a second wet solvent stream 532b from the pitch vacuum stripper, as described below, to form a combined wet solvent stream 532, which combined wet solvent stream 532 is compressed by compressor 536 and sent to solvent tank 540.

Pitch/solvent stream 514 passes through heat exchanger 542 and is heated by heat exchanger 542, is further heated by heater 548, and is introduced to flash separator 550, which flash separator 550 separates solvent stream 552 from concentrated pitch/solvent stream 554. Solvent stream 552 passes through heat exchanger 542 to preheat bitumen/solvent stream 514, is combined with solvent stream 522 removed from the deasphalted oil, and is sent to solvent tank 540.

Concentrated pitch/solvent stream 554 is introduced into pitch vacuum stripper 560 along with steam 562, which steam 562 separates wet solvent stream 532b from pitch stream 564, pitch stream 564 can be processed, discarded, and/or used for any desired purpose, such as paving pitch, and/or recycled to a hydroprocessing reactor to provide additional dispersed metal sulfide catalyst particles that remain in the pitch. As described above, wet solvent stream 532b is combined with wet solvent stream 536a from DAO vacuum stripper 530.

Make-up solvent 544 is introduced into a solvent tank 540, the solvent tank 540 separating water 546 from dehydrated solvent 548, the dehydrated solvent 548 being separated into first and second solvent streams 506a, 506b and introduced into extractor unit 502 as described above.

Fig. 6 schematically illustrates a hydrotreating and deasphalting system 600 that can be used in accordance with the disclosed methods and systems, which include sequential addition of dispersed metal sulfide catalyst for efficient hydrotreating of heavy oils. The system 600 shows the sequential addition and incorporation of a dispersed metal sulfide catalyst according to the present invention into an SDA unit in an ebullated-bed unit. The hydroprocessing and deasphalting system 600 includes subsystems for heavy oil hydroprocessing, solvent deasphalting, and deasphalting oil hydroprocessing and is configured to more efficiently and effectively hydrotreat and deasphalt the heavy oil feedstock 602 according to the methods and systems disclosed herein.

The catalyst precursor 604 can advantageously be mixed with a hydrocarbon diluent to form a first diluted precursor mixture stream 604a, which catalyst precursor 604 is mixed with the heavy oil feedstock 602 using one or more mixers (not shown) to form a conditioned feedstock 606. The conditioned feedstock 606 passes through a heater 608 to at least partially thermally decompose the catalyst precursor 604 and release metal that reacts with sulfur in the heavy oil feedstock 602 and/or hydrogen sulfide gas added to the mixture to form dispersed metal sulfide catalyst particles in situ in the heavy oil feedstock 602. The heavy oil feedstock 602 with dispersed catalyst particles formed in situ from heater 608 is combined with a first stream 610a of heated and compressed hydrogen and introduced into a first ebullated bed hydroprocessing reactor 614. The first ebullated-bed reactor 614 is operated at desired hydroprocessing conditions, including desired reactor severity based on temperature, conversion, and throughput, to produce upgraded heavy oil 616.

Upgraded heavy oil 616 from first ebullated-bed reactor 614 is introduced into a first separator 618, such as a thermal separator, which first separator 618 separates a first volatilized stream 620 of gas and hydrocarbon vapors from a first liquid hydrocarbon stream 622. The volatilized stream 620 is mixed with a second volatilized stream 680 of gas and hydrocarbon vapors produced by the deasphalted oil hydroprocessing subsystem, as described below, and passed through the gas cooling unit 624. The cooled combined stream is introduced to a second separator 626, such as a flash separator, to remove a gas stream 628 from a second liquid hydrocarbon stream 630.

The gas stream 628 is passed through a high pressure amine scrubber 632 to produce a partially purified gas stream 634, which partially purified gas stream 634 is passed through a hydrogen purification unit 636 to produce purified hydrogen 638. Purified hydrogen 638 is combined with make-up hydrogen 640 compressed using make-up hydrogen compressor 642 to form a combined hydrogen stream 610, which combined hydrogen stream 610 passes through recycle compressor 646, through heater 612, and is split into first and second gas streams 610a, 610b of heated and compressed hydrogen. As described above, the first hydrogen stream 610a is used in the first hydroprocessing reactor 614 for hydroprocessing heavy oils. As described below, the second hydrogen stream 610b is used in the second hydrotreatment reactor 674 to hydrotreat the deasphalted oil.

As described below, the first liquid hydrocarbon stream 622 from the first separator 618 is combined with the second liquid hydrocarbon stream 630 from the second separator 626 and the third liquid hydrocarbon stream 682 produced by the deasphalted oil hydroprocessing subsystem to form a combined liquid hydrocarbon stream 684. The combined liquid hydrocarbon stream 684 is introduced into an atmospheric distillation tower 650, which atmospheric distillation tower 650 separates volatilized atmospheric gas oil 652 from atmospheric bottoms 654. The atmospheric bottoms 654 is introduced into a vacuum distillation column 660 which separates a vacuum bottoms 664 from the volatilized vacuum gas oil 662.

The reduced pressure bottoms 664 are introduced into and processed by a solvent deasphalting system 666 (e.g., solvent deasphalting system 500 shown in fig. 5) to produce deasphalted oil 668 and asphalt 670. The deasphalted oil 668 is combined with the second diluted catalyst precursor stream 604b, passed through heater 672, combined with the second heated and compressed hydrogen stream 610b, and introduced into the second hydroprocessing reactor 674.

The second ebullated-bed reactor 674 is operated at desired hydroprocessing conditions, including desired reactor severity based on temperature, conversion, and throughput, to produce upgraded deasphalted oil 676. The upgraded deasphalted oil 676 is introduced to a third separator 678, such as a thermal separator, which third separator 678 separates the second volatilized stream 680 of gas and hydrocarbon vapors described above from the third liquid hydrocarbon stream 682. The second volatilized stream 680 is combined with the first volatilized stream 620 and further processed as described above. Third liquid hydrocarbon stream 682 is combined with first liquid hydrocarbon stream 622 and second liquid hydrocarbon stream 630 to form a combined liquid hydrocarbon stream 684, and further processed by atmospheric and vacuum distillation as described above.

Fig. 7 schematically illustrates another embodiment of a combined hydroprocessing and deasphalting system 700 for use according to the disclosed method and system with sequential addition of dispersed metal sulfide catalyst particles for efficient hydroprocessing of heavy oils. The combined hydroprocessing and deasphalting system 700 includes a heavy oil hydroprocessing subsystem having multiple (e.g., one or two) ebullated-bed reactors, a solvent deasphalting subsystem, and a deasphalting oil hydroprocessing subsystem having ebullated-bed reactors. For any given heavy oil feedstock, including lower quality opportunity feedstock, the system 700 maximizes catalyst efficiency and conversion product production rate. Heavy oil hydroprocessing, solvent deasphalting, and deasphalting oil hydroprocessing subsystems can include or be based on existing hydroprocessing and deasphalting technologies.

As shown in fig. 7, the combined hydroprocessing and deasphalting system 700 is configured to process a heavy oil feedstock 702. The catalyst precursor 703 is mixed with a hydrocarbon diluent 704 in a mixing system 705 to produce a diluted precursor mixture 706 that is added to the heavy oil feedstock 702 to form a conditioned feedstock. The mixing system 705 may include one or more mixers known in the art for mixing hydrocarbon materials, such as one or more static in-line mixers and/or high shear mixers. The diluted precursor mixture 706 can be mixed with the heavy oil feedstock 702 using one or more mixers known in the art for mixing hydrocarbon materials, such as one or more static in-line mixers and/or high shear mixers (not shown), to advantageously mix the catalyst precursor within the heavy oil 702 to a molecular level prior to thermally decomposing the catalyst precursor. Buffer tank 708 can help mix diluted precursor mixture 706 with heavy oil feedstock 702, provide extended residence time to enhance mixing, and accommodate different amounts of material and/or flow fluctuations.

The conditioned heavy oil feedstock 709 from buffer tank 708 is pressurized and preheated, which causes at least partial decomposition of the catalyst precursor and in situ formation of dispersed catalyst metal sulfide catalyst particles with heavy oil 702. Hydrogen 716 is pressurized, preheated and introduced into first ebullated bed reactor 710a along with conditioned, pressurized and preheated feed 709. The first ebullated-bed reactor 710a is operated at desired hydroprocessing conditions, including desired reactor severity based on temperature, conversion, and throughput, to produce a first upgraded hydrocarbon material 720a. The first ebullated-bed reactor 710a utilizes a dual catalyst system comprising dispersed catalyst metal sulfide catalyst particles and a heterogeneous ebullated-bed catalyst, both of which catalyze the advantageous hydrotreating reactions in the reactor 710 a.

The first upgraded hydrocarbon feedstock 720a, which contains substantially the same concentration of dispersed catalyst metal sulfide catalyst particles as used in the first ebullated bed reactor 710a, is introduced with additional hydrogen 716 into a second ebullated bed reactor 710b, which second ebullated bed reactor 710b is operated at desired hydroprocessing conditions, including desired reactor severity based on temperature, conversion and throughput, to produce a second upgraded hydrocarbon feedstock 720b. The second ebullated-bed reactor 710b utilizes a dual catalyst system comprising dispersed catalyst metal sulfide catalyst particles and a heterogeneous ebullated-bed catalyst, both of which catalyze the beneficial hydrotreating reactions in the reactor 710 b.

The second upgraded hydrocarbon material 720b (which contains residual dispersed catalyst metal sulfide catalyst particles) produced by the second ebullated-bed reactor 710b is introduced into a separator 771, such as a thermal separator or an inter-stage pressure differential separator, which separator 771 separates the gas and vaporized hydrocarbons 772 from the hydrocarbon bottoms 774 containing unconverted hydrocarbons and asphaltenes, metals, residual dispersed metal sulfide catalyst particles, deposits and other non-volatile materials.

The hydrocarbon bottoms 774 is sent to a solvent deasphalting system 776, such as solvent deasphalting system 500 shown in fig. 5, which separates the deasphalted oil 780 from the asphalt 782. At least a portion of the residual dispersed metal sulfide catalyst particles in hydrocarbon bottoms 774 typically remain in bitumen 782 rather than in deasphalted oil 780. In some cases, substantially all of the residual dispersed metal sulfide catalyst particles remain in pitch 782. Bitumen 782 may be used for any desired purpose, including pelletization and combustion as a fuel, as a recycle bitumen stream 786 to add make-up dispersed catalyst metal sulfide catalyst particles to a heavy oil hydroprocessing subsystem, or as bitumen 788 (e.g., for paving).

The deasphalted oil stream 780 is mixed with an additional amount of catalyst precursor 778, which additional amount of catalyst precursor 778 can be provided as a diluted precursor mixture similar to mixture 706, but typically at a concentration lower than that introduced into the first ebullated-bed reactor 710a, to form a conditioned deasphalted oil in which dispersed metal sulfide catalyst particles are formed in situ at or about the time of heating and thermal decomposition of the catalyst precursor. The conditioned deasphalted oil, with or without preheating, is introduced into the third ebullated-bed hydroprocessing reactor 710c along with pressurized hydrogen 716. The third reactor 710c is operated at desired hydroprocessing conditions, including desired reactor severity based on temperature, conversion, and throughput, to produce a third upgraded hydrocarbon material 720c. The third ebullated-bed reactor 710c utilizes a dual catalyst system comprising dispersed catalyst metal sulfide catalyst particles and a heterogeneous ebullated-bed catalyst, both of which catalyze beneficial hydrotreating reactions in the reactor 710 c.

The third upgraded hydrocarbon material 720c produced by the third ebullated-bed reactor 710c is combined with the gas and vaporized hydrocarbons 772 from the separator 771 of the heavy oil hydroprocessing subsystem and sent to the high temperature separator 742a (i.e., thermal separator). The high temperature separator 742a separates the gas and hydrocarbon vapor 746a from the first non-volatile liquid hydrocarbon 748 a. The volatilized material 246a passes through a heat exchanger 750, which heat exchanger 750 removes heat for preheating the hydrogen gas 716 prior to feeding the hydrogen gas 716 to the ebullated-bed reactors 710a, 710b, 710 c. The somewhat cooled volatile fraction 746a is sent to a medium temperature separator 742b, which medium temperature separator 242b separates the remaining volatile material 746b from the second non-volatile liquid hydrocarbons 748b formed as a result of the cooling by the heat exchanger 750. Remaining volatile material 746b is sent to cryogenic separator 242c for further separation into gaseous material 752c and first degassed liquid 748c.

The second non-volatile liquid hydrocarbon 748b from the middle temperature separator 742b is combined with the first non-volatile liquid hydrocarbon 748a from the high temperature separator 742a and the combined liquid hydrocarbon stream is sent to the low pressure separator 742d. The low pressure separator 742d separates the hydrogen-rich gas 752d from a second degassed liquid 748d, which second degassed liquid 748d is sent to a back end system 760 together with the first degassed liquid 748c from the low temperature separator 742c, which back end system 760 comprises one or more distillation columns (including a reduced pressure distillation column) in which the material is fractionated into products comprising light hydrocarbons and distillation bottoms.

The gaseous stream 752c from the cryogenic separator 742c is purified into exhaust gas, bleed gas (purge gas) and hydrogen 716. The hydrogen 716 is compressed, mixed with the compressed make-up hydrogen 716a, and either passed through a heat exchanger 750, heated and introduced into the first ebullated bed reactor 710a, or introduced directly into the second and third ebullated bed reactors 710b and 710 b.

Fig. 8 schematically illustrates an exemplary ebullated-bed hydroprocessing system 800 that utilizes a dual catalyst system of dispersed metal sulfide catalyst particles and heterogeneous ebullated-bed catalyst. Ebullated bed hydroprocessing system 800 can be used for a heavy oil hydroprocessing subsystem and a deasphalted oil hydroprocessing subsystem of a combined method and system. The dispersed metal sulphide catalyst particles may be produced separately and then added to the ebullated bed reactor, together with the heterogeneous catalyst, to form a dual catalyst system. Alternatively or additionally, at least a portion of the dispersed metal sulfide catalyst particles may be generated in situ within the ebullated bed reactor.

Ebullated bed hydroprocessing system 800 includes ebullated bed reactor 830 and separator 804 (e.g., a thermal separator or distillation column). The catalyst precursor 802 and hydrocarbon diluent 804 are mixed in one or more premixers 806 to form a diluted precursor mixture 809. Diluted precursor mixture 809 is added to heavy oil or deasphalted oil feedstock 808 and mixed with the feedstock in one or more mixers 810 to form a conditioned feedstock 811. The conditioned feedstock 811 is fed into a buffer vessel 812 with a pump around loop 814 to achieve further mixing and dispersion of the catalyst precursor 802 within the feedstock 808. The conditioned feedstock from buffer vessel 812 is pressurized by one or more pumps 816, passed through preheater 818, and enters ebullated bed reactor 830 along with hydrogen 820 through inlet 836 at or near the bottom of ebullated bed reactor 830.

Ebullated-bed reactor 830 includes hydrocarbon feed 826 and expanded catalyst section 842, which expanded catalyst section 842 contains heterogeneous catalyst 844 typically used in ebullated-bed reactors. The lower heterogeneous catalyst free zone 848 is located below the expanded catalyst zone 842 and the upper heterogeneous catalyst free zone 850 is located above the expanded catalyst zone 842. Dispersed metal sulfide catalyst particles 824 are dispersed throughout hydrocarbon feed 826 within ebullated-bed reactor 830, including in expanded catalyst zone 842 and heterogeneous catalyst-free zones 848, 850, so that beneficial upgrading reactions can be promoted in the absence of catalyst.

The hydrocarbon material 826 in the ebullated bed reactor 830 is continuously recycled from the upper heterogeneous catalyst free zone 850 to the lower heterogeneous catalyst free zone 848 via a recycle passage 852 connected to a ebullating pump 854. At the top of the recirculation channel 852 is a funnel-shaped recirculation cup 856 through which the hydrocarbon feed 826 containing the dispersed catalyst particles 824 is withdrawn from the upper heterogeneous catalyst free zone 850. Recycled hydrocarbon feed 826 is mixed with fresh modulated feedstock and hydrogen 820.

Fresh heterogeneous catalyst 844 is introduced into ebullated-bed reactor 830 through catalyst inlet pipe 858 and spent heterogeneous catalyst 844 is withdrawn through catalyst withdrawal pipe 860. The dispersed metal sulfide catalyst particles 824 provide additional catalytic activity in the expanded catalyst region 842, the recirculation channel 852, and the lower and upper heterogeneous catalyst-free regions 848, 850. The addition of hydrogen to the hydrocarbon outside of heterogeneous catalyst 844 minimizes the formation of deposits and coke precursors, which typically result in deactivation of the heterogeneous catalyst.

The ebullated bed reactor 830 also includes an outlet 838 at or near the top through which the converted material 840 is withdrawn 838. The converted material 840 is introduced into a separator 804, which separator 804 separates one or more volatile fractions 805 withdrawn from the top of the thermal separator 804 from a residuum fraction 407 withdrawn from the bottom of the separator 804. Resid fraction 807 contains residual dispersed metal sulfide catalyst particles, schematically depicted as catalyst particles 824. If desired, at least a portion of residuum fraction 807 can be recycled back to ebullated bed reactor 830 to form a portion of the feed material and provide additional dispersed metal sulfide catalyst particles. Alternatively, residuum fraction 807 can be further processed using downstream processing equipment, such as another ebullated bed reactor, a distillation column, a deasphalting unit, and the like.

The hydrotreating system is typically configured and operated to promote a hydrocracking reaction rather than a less severe hydrotreating reaction, such as hydrotreating. Hydrocracking involves breaking of carbon-carbon molecular bonds, e.g., reducing the molecular weight of larger hydrocarbon molecules and/or ring opening of aromatics. On the other hand, hydrotreating mainly involves the hydrogenation of unsaturated hydrocarbons, in which carbon-carbon molecular bonds are rarely or not broken.

In order to promote more severe hydrocracking reactions rather than less severe hydrotreating reactions, the hydroprocessing reactor is preferably operated at a temperature in the range of about 750°f (399 ℃) to about 860°f (460 ℃) more preferably in the range of about 780°f (416 ℃) to about 830°f (443 ℃), preferably in the range of about 1000psig (6.9 MPa) to about 3000psig (20.7 MPa), more preferably at a pressure in the range of about 1500psig (10.3 MPa) to about 2500psig (17.2 MPa), and preferably at a space velocity (LHSV) in the range of about 0.05hr "1 to about 0.45 hr" 1, more preferably in the range of about 0.1hr "1 to about 0.35 hr" 1. The difference between hydrocracking and hydrotreating can also be expressed in terms of resid conversion (where hydrocracking results in substantial conversion of higher boiling hydrocarbons to lower boiling hydrocarbons, while hydrotreating does not).

The hydrotreating systems disclosed herein can result in a total residuum conversion in the range of from about 60% to about 95%, preferably in the range of from about 75% to about 90%. The preferred conversion range generally depends on the type of feedstock due to differences in processing difficulties between different feedstocks.

Operating an ebullated bed reactor with a dual catalyst system may result in the same or reduced equipment fouling as compared to operating an ebullated bed reactor with only a heterogeneous catalyst. For example, when a dual catalyst system is used rather than a heterogeneous catalyst alone, the equipment fouling rate may provide one or more of the following benefits: (i) Reducing the frequency of heat exchanger shutdowns and/or distillation column shutdowns for cleaning; (ii) Reducing the frequency of changing or cleaning filters and strainers; (iii) reducing the frequency of replacement of the backup heat exchanger; (iv) Reducing the rate of decrease of the surface layer temperature in heat exchangers, separators or distillation columns and the like; (v) reducing the rate of increase of the furnace tube metal temperature; and (vi) reducing the rate of increase of the calculated fouling resistance coefficient of the heat exchanger.

Fig. 9 schematically illustrates a pilot plant 900 comprising ebullated-bed reactors 912, 912' that can be used to test and verify aspects of the heavy oil hydrotreating and deasphalting oil hydrotreating subsystem used in the combined hydrotreating and deasphalting methods and systems disclosed herein. Pilot plant 900 includes a mixing device 902 for mixing a heavy oil or deasphalted oil feedstock, a hydrocarbon diluent, and a catalyst precursor (e.g., molybdenum 2-ethylhexanoate, 15 wt.% molybdenum) with a heavy oil feedstock (collectively 501) to form a conditioned feedstock. The dashed line represents batch processing, although it is within the scope of the present disclosure to use continuous processing. More thorough mixing is achieved by first premixing the catalyst precursor with a hydrocarbon diluent to form a diluted precursor mixture, and then mixing the diluted precursor mixture with the feedstock. The hydrotreated heavy vacuum gas oil can be used as a hydrocarbon diluent. In one embodiment, a diluted precursor mixture may be prepared such that 1 part by weight of the diluted precursor mixture may be added to 99 parts by weight of the feedstock to achieve a target loading of dispersed metal sulfide catalyst particles in the feedstock. For example, for a test study of a target loading of 30ppm dispersed metal sulfide catalyst particles in a conditioned feedstock (where the loading is expressed based on the metal concentration, rather than the total weight of the catalyst precursor), a diluted catalyst precursor mixture was prepared to include 3000ppm metal.

For comparative test studies without using a dispersed metal sulfide catalyst, a hydrocarbon diluent (e.g., hydrotreated heavy vacuum gas oil) can be added to the feedstock in the same ratio of 1 part by weight HVGO to 99 parts by weight feedstock. This ensures that the background composition is the same between the test using a dual catalyst system and the test using only a heterogeneous ebullated bed catalyst, thereby allowing direct comparison of test results.

Heterogeneous catalysts are commercially available catalysts commonly used in ebullated bed reactors. The conditioned feedstock is recycled out through pump 904 and back into mixing vessel 902, which is conceptually similar to buffer vessels and pump-around in commercial units. A high precision positive displacement pump 906 is used to draw the conditioned feedstock from the recirculation loop and pressurize it to reactor pressure. Hydrogen gas 908 is fed into the pressurized feedstock and the resulting mixture is passed through a preheater 910 prior to being introduced into the first pilot scale ebullated bed reactor 912.

In some embodiments, each pilot scale ebullated bed reactor 912, 912' may have an internal volume of about 3000ml, although other dimensions may be used as desired. The settling height of the catalyst in each ebullated-bed reactor 912, 912' is schematically represented by the lower dashed line 916, and the upper expansion of the expanded catalyst bed during use is schematically represented by the upper dashed line 918. The mesh guard 914 serves to prevent the heterogeneous catalyst from inadvertently escaping the reactor. Each reactor 912, 912 'is also equipped with a recirculation line 911, 911' and a recirculation pump 913, 913 'which provide the required flow rate in the reactor 912, 912' to expand the heterogeneous catalyst bed. In some embodiments, the combined volume of the two reactors 912, 912 'and their respective recycle lines 911, 911' may be 6700ml, although other volumes may be used as desired. The combined volume is the thermal reaction volume of the system and can be used as the basis for calculating the liquid space velocity (LHSV), which is similar to the throughput but is normalized to eliminate the reactor size and inversely proportional to the residence time of the hydrocarbon feed in the reactors 912, 912'.

The upgraded hydrocarbon material produced by the first reactor 912 is transferred to a second reactor 912 'along with make-up hydrogen 908' for further hydroprocessing and upgrading. Further upgraded material 920 'from the second reactor 912' may be introduced into a thermal separator 922 to separate low boiling hydrocarbon products and gases 924 from unconverted liquid fraction 926. The hydrocarbon product vapor and gas 924 are cooled and sent to a cold separator 928 which further separates them into gas 930 and a converted hydrocarbon product, which is recovered as separator overhead 932.

The liquid fraction 926 from the thermal separator 922 may be further processed using a separate (off-line) batch vacuum distillation apparatus (not shown) to produce a separator bottoms 934. While the reduced pressure distillation in commercial units is performed in a continuous in-line distillation column, batch distillation units can be used for pilot plant testing for further investigation.

Hydrotreating and deasphalting process

Fig. 10-12 are flow diagrams illustrating an example method of hydrotreating heavy oils in combination with solvent deasphalting and sequential addition of dispersed metal sulfide catalyst.

Fig. 10 illustrates an exemplary method 1000 for sequential addition of dispersed metal sulfide catalyst in combination with solvent deasphalting for efficient hydroprocessing of heavy oils.

Step 1002 includes the steps of adding a first amount of catalyst precursor to the heavy oil and heating the heavy oil to form first dispersed metal sulfide catalyst particles in situ within the heavy oil. As discussed herein, the catalyst precursor decomposes when heated above its decomposition temperature to release the metal and react with sulfur in the heavy oil to form dispersed metal sulfide catalyst particles. Advantageously, the catalyst precursor is highly dispersed throughout the heavy oil to form the conditioned feedstock prior to thermally decomposing the catalyst precursor and forming the metal sulfide catalyst particles. The more thoroughly and finely dispersed the catalyst precursor throughout the heavy oil, the smaller the catalyst particles obtained. Smaller catalyst particles are more numerous and have a higher surface area than larger catalyst particles, thereby greatly increasing catalytic activity.

To ensure adequate mixing of the catalyst precursor within the heavy oil, it is advantageous to first mix the catalyst precursor with a hydrocarbon diluent to form a catalyst precursor mixture, and then mix the catalyst precursor mixture with the heavy oil to form the conditioned feedstock. Because hydrocarbon diluents generally do not require as high a temperature as heavy oil to maintain a flowable liquid, forming a catalyst precursor mixture is advantageous because it can further help prevent premature thermally induced decomposition of the catalyst precursor prior to complete mixing throughout the heavy oil.

Step 1004 includes the step of hydrotreating a heavy oil containing first dispersed metal sulfide catalyst particles under hydrotreating conditions in one or more reactors to produce upgraded heavy oil containing conversion products. The hydrotreating conditions may be any conditions suitable for hydrotreating heavy oils. In some embodiments, the hydroprocessing conditions may be hydrocracking conditions, as discussed herein. The hydroprocessing of heavy oils can be carried out using known hydroprocessing reactors, including ebullated bed reactors, fixed bed reactors, and slurry phase reactors.

The effluent from the one or more hydroprocessing reactors is subjected to one or more separation processes, such as flash separation, thermal separation, atmospheric distillation, and vacuum distillation, to separate one or more volatile materials from a liquid hydrocarbon feed containing asphaltenes, metals, dispersed metal sulfide catalyst particles, precipitates, high boiling hydrocarbons, and other non-volatile materials.

Step 1006 includes solvent deasphalting at least a portion of the upgraded heavy oil produced in step 1004 to produce deasphalted oil and bitumen; advantageously, the material subjected to solvent deasphalting is advantageously a liquid hydrocarbon material produced in step 1004 by subjecting the upgraded heavy oil to one or more separation processes. This ensures that the more valuable hydrocarbon products are not affected by solvent deasphalting, which reduces the overall efficiency and economic benefits of hydrotreating in combination with solvent deasphalting. Step 1006 of solvent deasphalting the hydrocarbon residuum or bottoms can be performed using known solvent deasphalting processes. In some embodiments, solvent deasphalting can be performed using the solvent deasphalting system shown in fig. 5 and/or the solvent deasphalting process shown in fig. 12 and discussed herein.

Step 1008 includes adding a second amount of catalyst precursor to the deasphalted oil produced in step 1006 and heating the deasphalted oil to form second dispersed metal sulfide catalyst particles in situ within the deasphalted oil. Because the catalyst precursor typically thermally decomposes upon heating above its decomposition temperature, it is advantageous that the catalyst precursor is highly dispersed throughout the deasphalted oil to form a conditioned deasphalted feedstock before thermally decomposing the catalyst precursor and forming the second metal sulfide catalyst particles. The more thoroughly and finely dispersed the catalyst precursor throughout the deasphalted oil, the smaller and the more catalytically active the resulting catalyst particles. Advantageously, a second amount of catalyst precursor is mixed with a hydrocarbon diluent to form a second catalyst precursor mixture, which is then mixed with a deasphalted oil to form a conditioned deasphalted oil, which is then heated and in situ formed into second dispersed metal sulfide catalyst particles.

Step 1010 includes the step of hydrotreating the deasphalted oil containing the second dispersed metal sulfide catalyst particles under hydrotreating conditions in one or more reactors to produce an upgraded deasphalted oil containing conversion products. The hydrotreating conditions may be any conditions suitable for hydrotreating a deasphalted oil. In some embodiments, the hydrotreating conditions may be hydrocracking conditions. Hydrotreatment of the deasphalted oil can be carried out using known hydrotreatment reactors, including ebullated bed reactors, fixed bed reactors, and slurry phase reactors.

The effluent from the one or more deasphalted oil hydroprocessing reactors is subjected to one or more separation processes, such as flash separation, thermal separation, atmospheric distillation, and vacuum distillation, to separate one or more volatile materials from the non-volatile materials containing asphaltenes, metals, dispersed metal sulfide catalyst particles, precipitates, high boiling hydrocarbons, and other insoluble materials. Advantageously, as shown in fig. 6, the non-volatile material is solvent deasphalted, e.g., by one or more separation processes after heavy oil hydroprocessing, is combined with the residual material produced in step 1004, and then solvent deasphalting is performed in step 1006.

Fig. 11 illustrates another exemplary method 1100 of sequentially adding a dispersed metal sulfide catalyst in combination with solvent deasphalting for effective hydroprocessing of heavy oils. The process 1100 is particularly directed to hydroprocessing heavy oils and deasphalted oils using one or more ebullated bed reactors.

Step 1102 includes the step of heating a heavy oil containing a first amount of catalyst precursor to form first dispersed metal sulfide catalyst particles in situ within the heavy oil. As described herein, it is advantageous that the catalyst precursor is highly dispersed throughout the heavy oil before thermally decomposing the catalyst precursor and forming the metal sulfide catalyst particles. To ensure adequate mixing of the catalyst precursor in the heavy oil, the catalyst precursor may be premixed with a hydrocarbon diluent to form a catalyst precursor mixture that is mixed with the heavy oil to form a conditioned heavy oil prior to in situ formation of the dispersed metal sulfide catalyst particles.

Step 1104 includes the step of hydrotreating heavy oil in a first ebullated-bed hydrotreating reactor using a dual catalyst system comprising a heterogeneous ebullated-bed catalyst and first dispersed metal sulfide catalyst particles at a desired severity based on temperature, conversion, and yield to produce upgraded heavy oil containing conversion products. The hydrotreating conditions may be any conditions suitable for hydrotreating heavy oils, such as hydrocracking conditions.

Step 1106 includes the step of hydrotreating at least a portion of the upgraded heavy oil (e.g., liquid hydrocarbon material resulting from the one or more separation processes) from step 1104 in a second ebullated-bed hydroprocessing reactor operating at desired severity conditions in terms of temperature, conversion, and throughput to produce a second upgraded heavy oil containing conversion products using a dual catalyst system comprising heterogeneous ebullated-bed catalyst and first dispersed sulfided metal catalyst particles.

Step 1108 includes subjecting the first upgraded heavy oil and/or the second upgraded heavy oil to one or more separation processes, such as thermal separation, atmospheric distillation, and vacuum distillation, to separate one or more lower boiling fractions from one or more liquid hydrocarbons, which fractions typically contain asphaltenes, metals, first dispersed metal sulfide catalyst particles, deposits, high boiling hydrocarbons, and other non-volatile materials.

Step 1110 includes solvent deasphalting at least a portion of the one or more liquid hydrocarbon fractions from step 1108 to produce deasphalted oil and bitumen. Solvent deasphalting can be carried out using known solvent deasphalting methods and systems. In some embodiments, solvent deasphalting can be performed using the solvent deasphalting system shown in fig. 5 and/or the solvent deasphalting process shown in fig. 12 and discussed herein.

Step 1112 includes the step of heating the deasphalted oil from step 1110 containing a second amount of catalyst precursor to form second dispersed metal sulfide catalyst particles in situ within the deasphalted oil. It is advantageous to disperse the catalyst precursor throughout the deasphalted oil before the catalyst precursor thermally decomposes and forms metal sulfide catalyst particles. To ensure adequate mixing of the catalyst precursor in the deasphalted oil, the catalyst precursor may be premixed with a hydrocarbon diluent to form a diluted precursor mixture that is mixed with the deasphalted oil to form a conditioned deasphalted oil before forming the second amount of dispersed metal sulfide catalyst particles in situ.

Step 1114 includes the step of hydrotreating the deasphalted oil, for example, in an ebullated-bed hydrotreating reactor operating under desired severity conditions based on temperature, conversion, and yield, using a dual catalyst system comprising heterogeneous ebullated-bed catalyst and second dispersed metal sulfide catalyst particles to produce an upgraded deasphalted oil containing conversion products. The hydrotreating conditions may be any conditions suitable for hydrotreating a deasphalted oil, such as hydrocracking conditions.

The effluent from hydrotreating the deasphalted oil may be subjected to one or more separation processes, such as flash separation, thermal separation, atmospheric distillation, and vacuum distillation, to separate one or more volatile fractions from the non-volatile fraction containing asphaltenes, metals, dispersed metal sulfide catalyst particles, precipitates, high boiling hydrocarbons, and other insoluble materials. The non-volatile material may also be subjected to solvent deasphalting, as shown in fig. 6, for example by one or more separation methods, combined with the residue material produced in one or both of steps 1104, 1106, and subjected to solvent deasphalting in step 1110.

FIG. 12 illustrates an exemplary method 1200 of solvent deasphalting a hydrocarbon residuum feed to separate insoluble asphalt from soluble deasphalted oil. Method 1200 may be performed using any desired solvent deasphalting system, such as deasphalting system 500 shown in fig. 5 or the like.

Step 1202 includes introducing a hydrocarbon residuum material and a solvent into an extractor unit, mixing the hydrocarbon residuum and the solvent upstream of and/or in the extractor unit. The solvent may be any solvent suitable for solvent deasphalting of hydrocarbon materials containing insoluble materials such as asphaltenes, metals, dispersed metal sulfide catalyst particles, deposits and other solid materials. Advantageously, paraffinic solvents such as propane, butane, pentane, hexane, and heptane may be used and are capable of effectively dissolving soluble hydrocarbons and having a viscosity low enough to exclude insoluble bitumen material, for example, by centrifugation and/or gravity settling. Lighter solvents (e.g. C ₃ And C ₄ ) A large amount of aromatic compounds and resins are discharged and a lower lift of "DAO" is achieved, while a heavier solvent (e.g. C ₅ -C ₇ ) More aromatics and resins are extracted and thus lift is higher.

Step 1204 includes removing a first stream from the extractor unit containing the dissolved hydrocarbon fraction and a first portion of the extraction solvent, and flash separating the first stream, followed by vacuum stripping, to produce a deasphalted oil and a first recovered solvent. As shown in fig. 5, the deasphalting system can include a series of flash separators that stage the removal of the extraction solvent from the deasphalted oil. This stepwise flash separation process maximizes the yield and minimizes the residence time in either flash separator. Vacuum stripping may further heat the liquid material remaining after flash separation with steam to ensure substantially complete removal of any remaining solvent from the deasphalted oil. Thus, the first recovered solvent may contain residual moisture, which may be removed, for example, using a solvent drum that allows phase separation and draining of the separated water.

Step 1206 includes removing a second stream from the extractor unit containing insoluble bitumen and a second portion of the solvent, and flash separating the second stream, followed by vacuum stripping, to produce bitumen and a second recovered solvent. As shown in fig. 5, the deasphalting system can include a heater to preheat the bitumen/solvent stream to ensure that a high percentage of residual solvent is removed by flash separation prior to vacuum stripping. This increases efficiency and reduces the need to use multiple flash separators. Vacuum stripping may utilize steam to further heat the residual bitumen/solvent mixture from the flash separator to ensure that any residual solvent is substantially completely removed from the bitumen. Thus, the second recovered solvent may contain residual moisture, which may be removed using a solvent drum that allows phase separation and draining of the separated water.

Step 1208 includes recycling at least a portion of the first and second recovered solvents to the extractor unit, optionally with make-up solvent, to compensate for solvent lost in the deasphalted oil and bitumen streams. The first portion of solvent may be added to the extractor unit along with the liquid hydrocarbon material undergoing solvent deasphalting, and the second portion of solvent may be added at or near the bottom of the extractor unit to aid in the removal of the bitumen/solvent stream. Without the addition of the second solvent, the bitumen may not flow but may solidify and/or otherwise accumulate in the extractor unit and/or downstream piping.

Step 1210 includes optionally recycling a portion of the bitumen produced in step 1208 as a source of supplemental dispersed metal sulfide catalyst particles to the heavy oil to be hydrotreated. The amount of bitumen that can be recycled may depend on whether it results in a recycle build-up of asphaltenes in the heavy oil hydroprocessing reactor. Recycling bitumen may be advantageous if the benefits of adding supplemental dispersed metal sulfide catalyst particles to the heavy oil are greater than the damage caused by bitumen (e.g., increased fouling, deactivation of ebullated bed catalyst, and/or lower conversion of the heavy oil). By carefully monitoring equipment fouling and conversion product productivity, an operator can determine the optimal amount of bitumen that can be advantageously recycled.

Operating conditions and effects of methods and systems employing combined hydrotreating and deasphalting

The use of a dual catalyst system comprising a heterogeneous catalyst and dispersed metal sulfide catalyst particles allows the ebullated bed reactor to operate at significantly higher reactor severity without causing more equipment fouling and, in many cases, also can reduce equipment fouling, as compared to hydroprocessing systems that omit dispersed metal sulfide catalyst particles when hydroprocessing heavy oils and deasphalted oils (e.g., conventional ebullated bed reactors that utilize typical heterogeneous supported catalysts).

Furthermore, the methods and systems disclosed herein increase the total amount of conversion products produced from a given amount of heavy oil as compared to ebullated bed hydroprocessing systems that employ a dual catalyst system comprising a heterogeneous catalyst and dispersed metal sulfide catalyst particles to hydrotreat the heavy oil, but omit solvent deasphalting and sequential addition of the dispersed metal sulfide catalyst particles.

It has further been surprisingly and unexpectedly found that the amount of conversion product produced from a given amount of heavy oil feed can be increased even with the same or reduced total amount of catalyst precursor and dispersed metal sulfide catalyst particles. This is especially unexpected in view of the fact that a substantial portion of the dispersed metal sulfide catalyst particles used to hydrotreat heavy oils are removed in bitumen after solvent deasphalting of hydrocarbon residues from the hydrotreated heavy oils. Only a small amount (if any) of the dispersed metal sulfide catalyst particles remain in the deasphalted oil, which requires the addition of another amount of catalyst precursor to form the dispersed metal sulfide catalyst particles for hydrotreating the deasphalted oil. Even so, the use of a given amount of dispersed metal sulfide catalyst particles in the disclosed process and system results in the production of a greater amount of conversion products than ebullated bed hydroprocessing systems that use dual catalyst systems, but omit solvent deasphalting.

In general, the rate of conversion product production in hydroprocessing heavy oils and deasphalted oils can be increased by increasing the reactor severity, which is the amount of energy input into the system, for example, by one or more of the following: (i) Higher temperatures and higher conversions at the same or similar throughput; (ii) Higher temperatures and higher yields at the same or similar conversion; (iii) Higher temperature, higher throughput and higher conversion. The disclosed methods and systems allow ebullated-bed reactors to operate at significantly higher reactor severity without causing greater equipment fouling and in many cases with reduced equipment fouling, as compared to conventional systems for treating heavy oils.

In some embodiments, the production rate of the conversion product can be increased by increasing the production of heavy oil by at least 2.5%, at least 5%, at least 10%, or at least 20% while maintaining or increasing one or both of temperature and conversion.

In some embodiments, the rate of production of the conversion product can be increased by increasing the conversion of the heavy oil by at least 2.5%, at least 5%, at least 7.5%, at least 10%, or at least 15% while maintaining or increasing one or both of temperature and throughput.

In some embodiments, the rate of conversion product production may be increased by increasing the reactor operating temperature by at least 2.5 ℃, at least 5 ℃, at least 7.5 ℃, or at least 10 ℃, if the throughput remains unchanged or does not increase beyond a threshold level, which would result in an increase in conversion, the increased throughput at that threshold level would counteract the increased hydrotreating effect resulting from the increase in temperature, thereby not increasing conversion. In view of this, it will be appreciated that such an increase in operating temperature allows for an increase in the production of heavy oil without a decrease in conversion if the production does not increase beyond a threshold level at which the increased production exceeds the enhancement effect that counteracts the increased temperature.

In some embodiments, the disclosed methods and systems can reduce the rate of equipment fouling by at least 5%, 25%, 50%, or 75% as compared to the rate of equipment fouling of conventional systems for treating heavy oils.

In some embodiments, the dispersed metal sulfide catalyst particles are formed in situ within the bulk of the heavy oil or deasphalted oil added to the hydroprocessing reactor. This can be accomplished by the steps of: the catalyst precursor is first integrally mixed with the heavy oil or deasphalted oil to form a conditioned feedstock, and then the conditioned feedstock is heated to decompose the catalyst precursor and cause or allow the catalyst metal to react with sulfur and/or sulfur-containing molecules in and/or added to the heavy oil or deasphalted oil to form dispersed metal sulfide catalyst particles.

The catalyst precursor may be oil soluble and have a decomposition temperature in the range of about 100 ℃ (212°f) to about 350 ℃ (662°f), or in the range of about 150 ℃ (302°f) to about 300 ℃ (572°f), or in the range of about 175 ℃ (347°f) to about 250 ℃ (482°f). Examples of catalyst precursors include organometallic complexes or compounds, more particularly oil-soluble compounds or complexes of transition metals and organic acids, which decomposition temperatures or ranges are sufficiently high to avoid substantial decomposition when mixed with heavy oil or deasphalted oil feedstock under suitable mixing conditions. When mixing the catalyst precursor with the hydrocarbon oil diluent, it is advantageous to maintain the diluent at a temperature below that at which significant decomposition of the catalyst precursor occurs. One skilled in the art can select a mixing temperature profile that results in intimate mixing of the selected precursor composition without substantial decomposition prior to in situ formation of the dispersed metal sulfide catalyst particles.

Examples of catalyst precursors include, but are not limited to, molybdenum 2-ethylhexanoate, molybdenum octoate, molybdenum naphthenate, vanadium octoate, molybdenum hexacarbonyl, vanadium hexacarbonyl, and iron pentacarbonyl. Other catalyst precursors include molybdenum salts comprising a plurality of cationic molybdenum atoms and a plurality of carboxylate anions having at least 8 carbon atoms and being at least one of (a) aromatic, (b) alicyclic, or (c) branched, unsaturated, and aliphatic. For example, each carboxylate anion may have 8 to 17 carbon atoms or 11 to 15 carbon atoms. Examples of carboxylate anions consistent with at least one of the foregoing types include carboxylate anions derived from carboxylic acids selected from the group consisting of 3-cyclopentylpropionic acid, cyclohexane butyric acid, biphenyl-2-carboxylic acid, 4-heptylbenzoic acid, 5-phenylpentanoic acid, geranic acid (3, 7-dimethyl-2, 6-octadienoic acid), and combinations thereof.

In other embodiments, carboxylate anions suitable for use in preparing the oil-soluble, thermally stable molybdenum catalyst precursor compound are derived from carboxylic acids selected from the group consisting of 3-cyclopentylpropionic acid, cyclohexane butyric acid, biphenyl-2-carboxylic acid, 4-heptyl benzoic acid, 5-phenyl valeric acid, geranic acid (3, 7-dimethyl-2, 6-octadienoic acid), 10-undecylenic acid, dodecanoic acid, and combinations thereof. It has been found that molybdenum catalyst precursors prepared using carboxylate anions derived from the foregoing carboxylic acids have improved thermal stability.

The catalyst precursor having higher thermal stability may have a first decomposition temperature of greater than 210 ℃, greater than about 225 ℃, greater than about 230 ℃, greater than about 240 ℃, greater than about 275 ℃, or greater than about 290 ℃. Such catalyst precursors may have a peak decomposition temperature of greater than 250 ℃, or greater than about 260 ℃, or greater than about 270 ℃, or greater than about 280 ℃, or greater than about 290 ℃, or greater than about 330 ℃.

Although it is within the scope of the present invention to mix the catalyst precursor directly with the heavy oil or deasphalted oil feedstock, care must be taken in this case to mix the components for a sufficient time to thoroughly mix the catalyst precursor within the feedstock before substantial decomposition of the precursor composition has occurred. For example, U.S. patent No. 5578197 to Cyr et al, which is incorporated herein by reference in its entirety, describes a process wherein molybdenum 2-ethylhexanoate is mixed with an asphalt vacuum tower resid for 24 hours, and the resulting mixture is then heated in a reaction vessel to form an active catalyst and effect hydrocracking (see column 10, lines 4-43). While 24 hour mixing in laboratory scale testing may be acceptable for laboratory work, such long mixing times are generally not commercially and economically viable. To ensure that the catalyst precursor is thoroughly mixed within the heavy oil or deasphalted oil prior to heating to form the active catalyst, a series of mixing steps are performed by different mixing devices prior to heating the conditioned feedstock. These may include one or more low shear continuous (in-line) mixers followed by one or more high shear mixers, then a buffer vessel (purge) and pump-around system, followed by one or more multi-stage high pressure pumps for pressurizing the modulated feedstock prior to introducing it into the hydroprocessing reactor.

In some embodiments, the conditioned feedstock is preheated using a heating device prior to entering the hydroprocessing reactor to form at least a portion of the dispersed metal sulfide catalyst particles in situ within the heavy oil or deasphalted oil prior to entering the reactor. In other embodiments, the conditioned feedstock may be heated or further heated in a hydroprocessing reactor to form at least a portion of the dispersed metal sulfide catalyst particles in situ within the heavy oil or deasphalted oil.

In some embodiments, the dispersed metal sulfide catalyst particles may be formed in a multi-step process. For example, the oil soluble catalyst precursor composition may be premixed with a hydrocarbon diluent to form a diluted precursor mixture. Examples of suitable hydrocarbon diluents include, but are not limited to, vacuum gas oils (which typically have a nominal boiling range of 360-524 ℃ (680-975°f), decant or recycle oils (which typically have a nominal boiling range of 360 ° -550 ℃) (680-1022°f)), and atmospheric gas oils (which typically have a nominal boiling range of 200 ° -360 ℃ (392-680°f)), a portion of heavy oil or deasphalted oil feedstock, and other hydrocarbons that nominally boil at temperatures above about 200 ℃.

The ratio of catalyst precursor to hydrocarbon oil diluent used to prepare the diluted precursor mixture may be in the range of about 1:500 to about 1:1, or in the range of about 1:150 to about 1:2, or in the range of about 1:100 to about 1:5 (e.g., 1:100, 1:50, 1:30, or 1:10). The amount of catalyst metal (e.g., molybdenum) in the diluted precursor mixture is preferably from about 100ppm to about 7000ppm, more preferably from about 300ppm to about 4000ppm, by weight of the diluted precursor mixture.

Below the temperature at which the majority of the catalyst precursor decomposes, the catalyst precursor is advantageously mixed with a hydrocarbon diluent. The mixing may be performed at a temperature in the range of about 25 ℃ (77°f) to about 250 ℃ (482°f), or in the range of about 50 ℃ (122°f) to about 200 ℃ (392°f), or in the range of about 75 ℃ (167°f) to about 150 ℃ (302°f) to form a diluted precursor mixture. The temperature at which the diluted precursor mixture is formed may depend on the decomposition temperature and/or other characteristics of the catalyst precursor used and/or characteristics of the hydrocarbon diluent, such as viscosity.

The catalyst precursor is preferably mixed with the hydrocarbon oil diluent for a period of time of from about 0.1 seconds to about 5 minutes, or from about 0.3 seconds to about 3 minutes, or from about 0.5 seconds to about 1 minute, or from about 0.7 seconds to about 30 seconds, or from about 1 second to about 10 seconds. The actual mixing time depends at least in part on the temperature (i.e., it affects the fluid viscosity) and the mixing intensity. The mixing intensity depends at least in part on the number of stages, for example, for a continuous static mixer.

Premixing the catalyst precursor with a hydrocarbon diluent to form a diluted precursor mixture, which is then mixed with the heavy oil or deasphalted oil feedstock greatly facilitates thorough and intimate mixing of the catalyst precursor into the feedstock within the feedstock, particularly in the relatively short time periods required for large scale industrial operations. Forming a diluted precursor mixture shortens the overall mixing time by: (1) reducing or eliminating solubility differences between the more polar catalyst precursor and the more hydrophobic heavy oil or deasphalted oil feedstock, (2) reducing or eliminating rheological differences between the catalyst precursor and the heavy oil or deasphalted oil feedstock, and/or (3) decomposing (breaking up) the catalyst precursor molecules to form solutes within the hydrocarbon diluent that are more readily dispersed within the heavy oil or deasphalted oil feedstock.

The diluted precursor mixture is then combined with the heavy oil or deasphalted oil feedstock and mixed for a time and in a manner such that the catalyst precursor is dispersed throughout the heavy oil or deasphalted oil feedstock to form a conditioned feedstock, wherein the catalyst precursor is thoroughly mixed with the feedstock prior to thermal decomposition and in situ formation of the active metal sulfide catalyst particles. To obtain thorough mixing of the catalyst precursor within the feedstock, the diluted precursor mixture and the feedstock are advantageously mixed for a period of time in the range of about 0.1 seconds to about 5 minutes, or in the range of about 0.5 seconds to about 3 minutes, or in the range of about 1 second to about 1 minute. Increasing the intensity and/or shear energy of the mixing process generally reduces the time required to achieve adequate mixing.

Examples of mixing devices that may be used to achieve thorough mixing of the catalyst precursor and/or diluted precursor mixture with the heavy oil or deasphalted oil feedstock include, but are not limited to, high shear mixing, such as that produced in: a vessel having a propeller or turbine wheel; a plurality of static continuous mixers; a plurality of static continuous mixers in combination with a continuous high shear mixer; a plurality of static continuous mixers in combination with a continuous high shear mixer followed by a buffer vessel; combinations of the above followed by one or more multistage centrifugal pumps; and one or more multistage centrifugal pumps. According to some embodiments, high energy pumps having multiple chambers may be used for continuous rather than batch mixing, where the catalyst precursor composition and heavy oil or deasphalted oil feedstock are stirred and mixed as part of the pumping process itself. The mixing apparatus described above may also be used in the premixing process discussed above wherein the catalyst precursor is mixed with a hydrocarbon diluent to form a catalyst precursor mixture.

In the case of heavy oil feedstocks that are solid or extremely viscous at room temperature, it may be advantageous to heat the feedstock to soften it and produce a feedstock having a sufficiently low viscosity to allow good incorporation of the oil soluble catalyst precursor into the feedstock. In general, reducing the viscosity of a heavy oil feedstock will reduce the time required to thoroughly and intimately mix the oil-soluble precursor composition within the feedstock. However, it also leads to premature decomposition of the catalyst precursor. One can select a catalyst precursor having a decomposition temperature suitable for a given heavy oil feedstock.

The heavy oil feedstock and the catalyst precursor and/or diluted precursor mixture are advantageously mixed at a temperature in the range of about 25 ℃ (77°f) to about 350 ℃ (662°f), or in the range of about 50 ℃ (122°f) to about 300 ℃ (572°f), or in the range of about 75 ℃ (167°f) to about 250 ℃ (482°f) to produce a modulated feedstock.

Where the catalyst precursor is directly mixed with the heavy oil or deasphalted oil feedstock without first forming a diluted precursor mixture, the catalyst precursor and feedstock are advantageously mixed in the range of about 0.2 seconds to about 10 minutes, in the range of about 1 second to about 6 minutes, or in the range of about 2 seconds to about 2 minutes. Below the temperature at which most of the catalyst precursor composition decomposes, the catalyst precursor is advantageously mixed with the feedstock.

In the case where the catalyst precursor is premixed with a hydrocarbon diluent to form a diluted precursor mixture which is then mixed with the heavy oil or deasphalted oil feedstock, it may be permissible for the feedstock to be at or above the decomposition temperature of the catalyst precursor. In some cases, the hydrocarbon diluent shields individual catalyst precursor molecules and prevents them from agglomerating to form larger particles, temporarily isolates the catalyst precursor molecules from heat from the heavy oil or deasphalted oil during mixing, and promotes sufficiently rapid dispersion of the catalyst precursor molecules throughout the feedstock prior to decomposition to release of the metal. In addition, additional heating of the feedstock may be required to release hydrogen sulfide from sulfur-containing molecules in the heavy oil or deasphalted oil to form metal sulfide catalyst particles. In this way, the gradual dilution of the catalyst precursor allows for a high degree of dispersion in the heavy oil or deasphalted oil feedstock, resulting in the formation of highly dispersed metal sulfide catalyst particles, even if the feedstock is at a temperature above the decomposition temperature of the catalyst precursor.

After the catalyst precursor has been thoroughly mixed throughout the heavy oil or deasphalted oil to obtain a conditioned feedstock, the composition is heated to cause decomposition of the catalyst precursor, which releases the catalyst metal therefrom, causes or allows the catalyst metal to react with sulfur within and/or added to the heavy oil or deasphalted oil, and forms active metal sulfide catalyst particles in situ. The metal from the catalyst precursor may initially form a metal oxide which then reacts with sulfur in the heavy oil or deasphalted oil to produce a metal sulfide compound that forms the final active catalyst. Where the heavy oil and/or deasphalted oil feedstock contains sufficient or excess sulfur, the final activated catalyst can be formed in situ by heating the feedstock to a temperature sufficient to release sulfur therefrom. In some cases, sulfur may be released at the same temperature at which decomposition of the catalyst precursor occurs. In other cases, further heating to a higher temperature may be required. Hydrogen sulfide gas can be added to heavy oils or deasphalted oils lacking sufficient sulfur to form active metal sulfide catalyst particles.

If the catalyst precursors are thoroughly mixed throughout the heavy oil or deasphalted oil, at least a substantial portion of the released metal ions will be sufficiently shielded or shielded from other metal ions so that they can form a molecularly dispersed catalyst upon reaction with sulfur to form a metal sulfide compound. In some cases, minor agglomeration may occur, yielding colloidal sized catalyst particles. However, it is believed that attention is paid to thorough mixing of the catalyst precursor throughout the feedstock prior to thermal decomposition of the catalyst precursor may result in individual catalyst molecules rather than colloidal particles. The catalyst precursor is simply mixed with the starting materials, but not thoroughly mixed, often resulting in the formation of large agglomerated metal sulfide compounds of micron size or greater.

To form dispersed metal sulfide catalyst particles, the conditioned feedstock is heated to a temperature in the range of about 275 ℃ (527°f) to about 450 ℃ (842°f), or in the range of about 310 ℃ (590°f) to about 430 ℃ (806°f), or in the range of about 330 ℃ (626°f) to about 410 ℃ (770°f).

The concentration of catalyst metal provided by the dispersed metal sulfide catalyst particles in the heavy oil can be in the range of about 1ppm to about 150ppm, or in the range of about 5ppm to about 95ppm, or in the range of about 10ppm to about 90ppm, based on the weight of the heavy oil and any diluents.

The concentration of catalyst metal provided by the dispersed metal sulfide catalyst particles in the deasphalted oil can be in the range of about 0.1ppm to about 50ppm, or in the range of about 0.5ppm to about 30ppm, or in the range of about 1ppm to about 20ppm, based on the weight of the deasphalted oil.

The catalyst may become more concentrated as the volatile fraction is removed from the hydrotreated residual fraction. Recycling of the vacuum bottoms (vacuum bottoms) and/or bitumen may provide additional dispersed metal sulfide catalyst particles, which may maintain a desired concentration in the ebullated bed reactor while reducing the use of catalyst precursors, or which may increase the concentration of dispersed metal sulfide catalyst particles, which may help to provide additional asphaltenes for hydroprocessing from the recycled vacuum bottoms and/or bitumen.

Where the heavy oil or deasphalted oil contains a large number of asphaltene molecules, the dispersed metal sulfide catalyst particles may preferentially associate with or remain in close proximity to the asphaltene molecules. Asphaltene molecules can have a greater affinity for metal sulfide catalyst particles because asphaltene molecules are generally more hydrophilic and less hydrophobic than other hydrocarbons contained in heavy oils or deasphalted oils. Because the metal sulfide catalyst particles tend to be hydrophilic, individual particles or molecules will tend to migrate toward the more hydrophilic portions or molecules within the heavy oil feedstock.

Although the highly polar nature of the metal sulfide catalyst particles causes or allows them to associate with the asphaltene molecules, the general incompatibility between the highly polar catalyst compounds and the hydrophobic heavy oils and deasphalted oils necessitates the intimate or thorough mixing of the catalyst precursor composition within the feedstock prior to decomposition and in situ formation of the active catalyst particles. Because the metal catalyst compounds are highly polar, they cannot be effectively dispersed in heavy oil or deasphalted oil if added directly. In fact, the formation of smaller active catalyst particles results in a greater number of catalyst particles that provide a more uniform distribution of catalyst sites throughout the heavy oil. It also increases the catalyst surface area.

In some embodiments, the first amount of catalyst precursor added to the heavy oil is greater than the second amount of catalyst precursor added to the deasphalted oil. For example, the first amount of catalyst precursor added to the heavy oil may be at least about 25%, at least about 50%, at least about 75%, at least about 100%, at least about 150%, at least about 200%, at least about 300%, at least about 400%, or at least about 500% more than the second amount of catalyst precursor added to the deasphalted oil.

In some embodiments, the heavy oil includes a higher concentration of dispersed metal sulfide catalyst particles during hydroprocessing than the deasphalted oil. For example, the concentration of the dispersed metal sulfide catalyst particles in the heavy oil during hydroprocessing may be at least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 40%, or at least about 50% higher than the concentration of the dispersed metal sulfide catalyst particles in the deasphalted oil during hydroprocessing.

As an example of how an improved hydroprocessing system utilizes dispersed metal sulfide catalyst particles to more efficiently hydroprocessing heavy oils, the total amount of catalyst precursor required to produce a given amount of conversion product using the combined hydroprocessing and solvent deasphalting disclosed herein is less than the total amount of catalyst precursor required to produce the same given amount of conversion product without sequential addition of solvent deasphalting and dispersed metal catalyst particles (e.g., a hydroprocessing process or system that uses a dual catalyst system in an ebullated bed reactor without sequential addition of solvent deasphalting and dispersed metal catalyst particles). For example, the total amount of catalyst precursor required to produce a given amount of conversion product is reduced by at least about 2.5%, at least about 5%, at least about 10%, at least about 15%, at least about 20%, or at least about 25% as compared to the total amount of catalyst precursor required to produce the same given amount of conversion product in a hydroprocessing process or system that uses a dual catalyst system in an ebullated-bed reactor, but in the absence of solvent deasphalting and sequential addition of dispersed metal catalyst particles.

As another example of how an improved hydroprocessing system utilizes dispersed metal sulfide catalyst particles to more efficiently hydroprocessing heavy oils, the total amount of bitumen produced by solvent deasphalting after hydroprocessing heavy oils in the presence of the dispersed metal sulfide catalyst particles is less than the total amount of bitumen produced by solvent deasphalting without hydroprocessing heavy oils in the presence of the dispersed metal sulfide catalyst particles. For example, the total amount of bitumen produced by solvent deasphalting in the presence of dispersed metal sulfide catalyst particles is reduced by at least about 2.5%, at least about 5%, at least about 7.5%, at least about 10%, or at least about 15% in the presence of hydrotreated heavy oil compared to the total amount of bitumen produced by solvent deasphalting in the absence of hydrotreated heavy oil in the presence of dispersed metal sulfide particles.

It has been found that it may be advantageous to add or form a second amount of dispersed metal particles in the deasphalted oil when at least a portion of the first amount of dispersed metal sulfide catalyst particles remain in the asphalt after solvent deasphalting, i.e., when the deasphalted oil does not include all or a substantial portion of the first amount of dispersed metal sulfide catalyst particles contained in the upgraded heavy oil after hydroprocessing.

It has been found that at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, or at least about 80% of the first dispersed metal sulfide catalyst particles remain in the asphalt after solvent deasphalting such that the deasphalted oil contains as much dispersed metal sulfide catalyst particles as is spent as a result of being removed from the asphalt. In some cases, substantially all of the first dispersed metal sulfide catalyst particles remain in the bitumen and substantially no particles remain in the deasphalted oil.

Because bitumen may contain a large amount of dispersed metal catalyst particles, in some embodiments it may be advantageous to recycle at least a portion of the bitumen by adding the bitumen to the heavy oil to be hydrotreated to provide additional dispersed metal sulfide catalyst particles in addition to the first dispersed metal sulfide catalyst particles. The amount of recycled asphalt can be selected such that the benefits of including more dispersed metal sulfide catalyst particles outweigh the damage caused by adding asphalt to heavy oil.

The disclosed method and system for combining hydroprocessing of heavy oils and deasphalted oils with solvent deasphalting using a dispersed metal sulfide catalyst allows the ebullated bed reactor to operate at a higher overall severity than without solvent deasphalting, as compared to hydroprocessing heavy oils in an ebullated bed reactor using a dual catalyst system comprising a heterogeneous catalyst and dispersed metal sulfide catalyst particles, but omitting solvent deasphalting.

Additionally or alternatively, the disclosed methods and systems can increase the throughput of heavy oil by at least 2.5%, at least 5%, at least 10%, or at least 20% as compared to hydroprocessing without solvent deasphalting and sequential addition of dispersed metal sulfide catalyst particles.

Additionally or alternatively, the disclosed methods and systems can include increasing the conversion of heavy oil by at least 2.5%, at least 5%, at least 7.5%, at least 10%, or at least 15% as compared to hydrotreating without solvent deasphalting and sequential addition of dispersed metal sulfide catalyst particles.

The disclosed methods and systems for combining hydroprocessing heavy oils and deasphalted oils with dispersed metal sulfide catalysts with solvent deasphalting can reduce equipment fouling rates as compared to hydroprocessing heavy oils in ebullated bed reactors using a dual catalyst system comprising heterogeneous catalyst and dispersed metal sulfide catalyst particles, but omitting solvent deasphalting. In some embodiments, the disclosed methods and systems can reduce the rate of fouling of a plant by at least 5%, at least 10%, at least 15%, or at least 20% as compared to fouling of a plant using the same catalyst system at the same overall yield of conversion product in the absence of solvent deasphalting.

The rate of fouling of the equipment may be measured by at least one of the following methods: (i) the desired heat exchanger cleaning frequency; (ii) switching to a frequency of the backup heat exchanger; (iii) frequency of filter replacement; (iv) the frequency of filter (applicator) cleaning or replacement; (v) A rate of decrease of the surface temperature of a device comprising a device selected from the group consisting of a heat exchanger, a separator, or a distillation column; (vi) the rate of rise of furnace tube metal temperature; (vii) The rate of increase of the calculated fouling resistance coefficient of the heat exchanger and the furnace; (viii) a rate of increase in heat exchanger pressure differential; (ix) the frequency of cleaning the atmospheric and/or vacuum distillation columns; or (x) the frequency of maintenance turnarounds.

V. experimental study and results

Two case studies (examples 1 and 2) compare conventional hydrotreating and solvent deasphalting with sequential addition or formation of dispersed metal sulfide catalyst particles in heavy oils and deasphalted oils. It has been found that the use of dispersed metal sulfide catalyst particles can maximize the conversion of heavy oil in the hydroprocessing reactor prior to solvent deasphalting, thereby greatly improving the performance of the solvent deasphalting system and the overall performance of the overall process scheme. On the one hand, the use of dispersed metal sulphide catalyst particles increases the asphaltene conversion compared to the use of heterogeneous catalysts alone and significantly reduces the amount of bitumen that has to be processed and removed by the solvent deasphalting system.

Solvent deasphalting is expected to remove up to 60 wt.% of the dispersed metal sulfide catalyst particles used to hydrotreat the heavy oil. Based on this assumption, it is assumed that enough dispersed metal sulfide catalyst particles will remain in the deasphalted oil to ensure the efficiency of the overall process. In fact, it has been determined that most or all of the dispersed metal sulfide catalyst particles remain in the bitumen and are not carried into the deasphalted oil. Surprisingly and unexpectedly, the process is capable of more efficiently hydroprocessing a given amount of heavy oil with a given amount of catalyst precursor as compared to ebullated bed hydroprocessing systems that utilize a dual catalyst system to hydroprocessing heavy oil but omit solvent deasphalting.

Examples 1 and 2

In example 1, the design basis conversion was increased by 5% by volume with a constant sediment basis, as compared to a conventional hydroprocessing system employing solvent deasphalting but omitting dispersed metal sulfide catalyst particles. According to the test results reported below, conversion can be increased by more than 5% by volume without increasing deposit generation and equipment fouling.

In example 2, the yield was increased by 8.5% (482 tons/hr) at a constant conversion and sediment basis, compared to a conventional hydroprocessing system employing solvent deasphalting but omitting dispersed metal sulfide catalyst particles.

The improvements in overall process performance and yield benefits of the disclosed methods and systems compared to conventional hydrotreating and solvent deasphalting with the omission of dispersed metal sulfide catalyst particles are summarized in tables 1 and 2 below. The dispersed metal sulphide catalyst particles are abbreviated as "DMSC". The Baseline (Baseline) case is the traditional hydrotreating and solvent deasphalting omitting DMSC.

TABLE 1

TABLE 2

The improvements in product properties of unconverted oil are summarized in table 3 below:

TABLE 3 Table 3

The estimated economic benefits of more efficient production and higher quality products compared to baseline (no DMSC) are as follows:

example 1: $12.39MM per year

Example 2: $13.60MM per year

Additional $5-10MM savings are realized due to reduced equipment fouling, thereby reducing the number of shutdowns and washings.

Examples 3-5 compare the effects of using different combinations of ebullated bed hydroprocessing reactors, heterogeneous catalysts, use of dispersed metal sulfide catalyst particles, reactor conversion, total conversion, solvent deasphalting, and order of addition of catalyst precursors, and omission.

Comparative example 3

In comparative example 3, a system comprising three ebullated bed reactors utilizing a dual catalyst system comprising heterogeneous catalyst and dispersed metal sulfide catalyst particles (DMSC), but wherein the system omits solvent deasphalting, operates at high baseline conversions and medium baseline dispersed metal sulfide catalyst concentrations. The feed rate of the heavy oil was 400t/hr; the baseline feed rate of DMSC is standard; the overall conversion of heavy oil was 86.2%. The conversion product was produced at a rate of 344.8t/hr and the unconverted product was produced at a rate of 55t/hr.

Comparative example 4

In comparative example 4, a combined hydroprocessing and deasphalting system using heterogeneous catalysts but omitting dispersed metal sulfide catalyst particles included two ebullated bed reactors for hydroprocessing heavy oils and one ebullated bed reactor for hydroprocessing deasphalted oils. The heavy oil feed rate to the two heavy oil ebullated-bed reactors was 400t/hr and the conversion of the heavy oil was 70%. The production rate of the converted product was 280t/hr, and the production rate of the unconverted product was 120t/hr.

Unconverted product from the heavy oil hydroprocessing subsystem is solvent deasphalted with a lift of 60% or 72t/hr for deasphalted oil and a bitumen production rate of 48t/hr.

The feed rate of deasphalted oil to the ebullated bed reactor in the deasphalted oil hydroprocessing subsystem was 72t/hr and the conversion of deasphalted oil was 90%. Thus, the conversion product of the deasphalted oil hydroprocessing subsystem was produced at a rate of 64.8t/hr and the unconverted product was produced at a rate of 7.2t/hr.

Thus, the combined yield of bitumen and unconverted product of the combined heavy oil and deasphalted oil hydroprocessing system was 55.2t/hr and the total yield of converted product was 344.8t/hr, corresponding to a total conversion of 86.2%.

Example 5

In example 5, the combined hydroprocessing and deasphalting system utilizes a dual catalyst system of heterogeneous catalyst and dispersed metal sulfide catalyst particles, comprising two ebullated bed reactors for hydroprocessing heavy oils and a single ebullated bed reactor for hydroprocessing deasphalted oil. Example 5 also involves sequentially adding a first amount of catalyst precursor (DMSC) to heavy oil hydrotreated by the first two ebullated-bed reactors, and adding a second amount of catalyst precursor (DMSC) to deasphalted oil hydrotreated by the third ebullated-bed reactor.

The feed rate of heavy oil to the two heavy oil ebullated-bed reactors was 400t/hr; the DMSC feed rate to the heavy oil was 60% of baseline; the conversion of heavy oil was 75%. Thus, the conversion product of the heavy oil hydroprocessing subsystem is produced at a rate of 300t/hr and the unconverted product is produced at a rate of 100t/hr.

Solvent deasphalting the unconverted product of heavy oil hydrotreatment to obtain deasphalted oil with 60% lift rate or 60t/hr and asphalt production rate of 40t/hr. Substantially all of the dispersed metal sulfide catalyst particles used in the heavy oil hydroprocessing subsystem are removed from the bitumen by solvent deasphalting. Thus, substantially no dispersed metal sulfide catalyst particles remain in the deasphalted oil.

The feed rate of deasphalted oil to the ebullated bed reactor in the deasphalted oil hydroprocessing subsystem is 60t/hr; the feed rate of the second amount of DMSC to the deasphalted oil was 4.5% of baseline; the conversion of deasphalted oil is 95% and can be increased without increasing equipment fouling due to the presence of dispersed metal sulphide catalyst particles. Thus, the conversion product of the deasphalted oil hydroprocessing subsystem was produced at a rate of 57t/hr and the unconverted product was produced at a rate of 3.0t/hr.

Thus, the combined yield of bitumen and unconverted product of the combined heavy oil and deasphalted oil hydroprocessing system was 43t/hr, the total yield of converted product was 357t/hr, corresponding to 89.2% total conversion.

Notably, example 5 is able to increase the overall conversion and produce conversion products at a higher rate than comparative examples 3 and 4. Surprisingly and unexpectedly, example 5 is able to increase the overall conversion of heavy oil and produce conversion products at a higher rate than comparative example 3, despite the use of less catalyst precursor overall.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. A method for hydroprocessing heavy oils comprising:

adding a first amount of catalyst precursor to the heavy oil and heating the heavy oil to form first dispersed metal sulfide catalyst particles in situ within the heavy oil;

hydrotreating the heavy oil containing the first dispersed metal sulfide catalyst particles under hydrotreating conditions to produce upgraded heavy oil containing conversion products;

solvent deasphalting at least a portion of the upgraded heavy oil to produce deasphalted oil and bitumen;

adding a second amount of catalyst precursor to the deasphalted oil and heating the deasphalted oil to form second dispersed metal sulfide catalyst particles in situ within the deasphalted oil; and

hydrotreating the deasphalted oil containing the second dispersed metal sulfide catalyst particles under hydrotreating conditions to produce a upgraded deasphalted oil containing conversion products.

2. The process of claim 1 wherein heavy oil is hydrotreated in one or more hydrotreating reactors utilizing the first dispersed metal sulfide catalyst particles and operating under hydrotreating conditions.

3. The process of claim 1 or 2, wherein heavy oil is hydrotreated in one or more ebullated-bed reactors utilizing the first dispersed metal sulfide catalyst particles and a heterogeneous ebullated-bed catalyst and operating under hydrotreating conditions.

4. A process according to any one of claims 1 to 3, wherein the deasphalted oil is hydrotreated in one or more hydrotreating reactors using the second dispersed metal sulphide catalyst particles and operating under hydrotreating conditions.

5. The process of any one of claims 1 to 4, wherein deasphalted oil is combined with heterogeneous ebullated bed catalyst and optionally a residual portion of the first dispersed metal sulfide catalyst particles remaining in the deasphalted oil in one or more ebullated bed reactors with the second dispersed metal sulfide catalyst particles and is operated under hydrotreating conditions for hydrotreating.

6. The method of any of claims 1-5, further comprising separating the upgraded heavy oil into one or more lower boiling hydrocarbon fractions and one or more liquid hydrocarbon fractions, and solvent deasphalting at least a portion of the one or more liquid hydrocarbon fractions.

7. The method of claim 6, wherein the upgraded heavy oil is separated into one or more lower boiling hydrocarbon fractions and one or more liquid hydrocarbon fractions by one or more of flash separation, thermal separation, atmospheric distillation, or vacuum distillation.

8. The method according to claim 6 or 7, characterized in that the solvent deasphalting comprises:

introducing at least a portion of the one or more liquid hydrocarbon fractions and a solvent into an extractor unit and performing solvent deasphalting;

removing a first stream comprising the deasphalted oil and a first portion of the solvent from the extractor unit and subjecting the first stream to flash separation followed by vacuum stripping to produce the deasphalted oil and a first recovered solvent;

removing a second stream comprising bitumen and a second portion of solvent from the extractor unit, heating the second stream, and flash separating the second stream, followed by vacuum stripping to produce bitumen and a second recovered solvent; and

at least a portion of the first recovered solvent and the second recovered solvent are recycled to the extractor unit, optionally with make-up solvent.

9. The process according to any one of claims 1 to 8, wherein the solvent used in the solvent deasphalting step comprises at least one paraffinic solvent.

10. The method of any of claims 1-9, wherein the first amount of catalyst precursor added to the heavy oil is greater than the second amount of catalyst precursor added to the deasphalted oil.

11. The method of claim 10, wherein the first amount of catalyst precursor added to the heavy oil can be at least about 25%, at least about 50%, at least about 75%, at least about 150%, at least about 300%, at least about 600%, at least about 1200%, or at least about 2000% more than the second amount of catalyst precursor added to the deasphalted oil.

12. The method of any of claims 1-11, wherein the heavy oil comprises a higher concentration of dispersed metal sulfide catalyst particles during hydroprocessing than the deasphalted oil.

13. The method of claim 12 wherein the concentration of the dispersed metal sulfide catalyst particles in the heavy oil during hydroprocessing can be at least about 5%, at least about 10%, at least about 15%, at least about 30%, at least about 50%, at least about 75%, or at least about 100% higher than the concentration of the dispersed metal sulfide catalyst particles in the deasphalted oil during hydroprocessing.

14. The process of any one of claims 1 to 13, wherein the total amount of catalyst precursor required to produce a given amount of conversion product using combined hydrotreating and solvent deasphalting is less than the total amount of catalyst precursor required to produce a given amount of conversion product without solvent deasphalting and sequential addition of dispersed metal catalyst particles.

15. The method of claim 14, wherein the total amount of catalyst precursor required to produce a given amount of conversion product is reduced by at least about 2.5%, at least about 5%, at least about 10%, at least about 20%, at least about 30%, or at least about 50% compared to the total amount of catalyst precursor required to produce a given amount of conversion product without solvent deasphalting and sequential addition of dispersed metal catalyst particles.

16. The process of any one of claims 1 to 15, wherein the total amount of bitumen produced by solvent deasphalting after hydrotreating heavy oil in a ebullated bed reactor with dispersed metal sulfide particles and ebullated bed catalyst is less than the total amount of bitumen produced by solvent deasphalting after hydrotreating heavy oil in a ebullated bed reactor with ebullated bed catalyst in the absence of dispersed metal sulfide particles.

17. The method of claim 16, wherein the total amount of bitumen produced by solvent deasphalting after hydrotreating heavy oil in a ebullated bed reactor with dispersed metal sulfide catalyst particles and ebullated bed catalyst is reduced by at least about 2.5%, at least about 5%, at least about 10%, at least about 15%, or at least about 20% compared to the total amount of bitumen produced by solvent deasphalting after hydrotreating heavy oil in a ebullated bed reactor with ebullated bed catalyst in the absence of dispersed metal sulfide catalyst particles.

18. The method of any one of claims 1-17, wherein at least a portion of the first dispersed metal sulfide particles remain in the asphalt after solvent deasphalting.

19. The method of claim 18, wherein at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, or at least about 80% of the first dispersed metal sulfide particles remain in the asphalt after solvent deasphalting.

20. The method of any of claims 1-19, further comprising recycling at least a portion of the bitumen by adding the at least a portion of the bitumen to the hydrotreated heavy oil, the recycled bitumen providing additional dispersed metal sulfide catalyst particles in addition to the first dispersed metal sulfide catalyst particles.

21. The method of any one of claims 1 to 20, wherein the dispersed metal sulfide catalyst particles are less than 1 μιη in size, or less than about 500nm in size, or less than about 250nm in size, or less than about 100nm in size, or less than about 50nm in size, or less than about 25nm in size, or less than about 10nm in size.

22. The method of any one of claims 1 to 21, further comprising mixing a first amount of catalyst precursor with a first diluent hydrocarbon to form a first diluted precursor mixture, mixing the first diluted precursor mixture with the heavy oil to form a conditioned heavy oil, and heating the conditioned heavy oil to decompose the catalyst precursor and form first dispersed metal sulfide catalyst particles in situ within the heavy oil.

23. The method of any one of claims 1 to 22, further comprising mixing a second amount of catalyst precursor with a second diluted hydrocarbon to form a second diluted precursor mixture, mixing the second diluted precursor mixture with a deasphalted oil to form a conditioned deasphalted oil, and heating the conditioned deasphalted oil to decompose the catalyst precursor and form second dispersed metal sulfide catalyst particles in situ within the deasphalted oil.

24. A system for hydroprocessing heavy oils, comprising:

one or more mixers for mixing a first amount of catalyst precursor with the heavy oil to form a conditioned heavy oil, which upon heating to a temperature above the decomposition temperature of the catalyst precursor forms first dispersed metal sulfide catalyst particles in situ within the heavy oil;

one or more hydroprocessing reactors configured to hydroprocessing a heavy oil containing first dispersed metal sulfide catalyst particles under hydroprocessing conditions to produce upgraded heavy oil containing conversion products;

a solvent deasphalting system configured to receive at least a portion of the upgraded heavy oil and solvent and to perform solvent deasphalting to produce a deasphalted oil and bitumen;

One or more mixers for mixing a second amount of catalyst precursor with the deasphalted oil to form a conditioned deasphalted oil, which upon heating to a temperature above the decomposition temperature of the catalyst precursor forms second dispersed metal sulfide catalyst particles in situ within the deasphalted oil; and

one or more hydroprocessing reactors configured to hydrotreat the deasphalted oil under hydroprocessing conditions to produce an upgraded deasphalted oil containing conversion products.

25. The system of claim 24, wherein the one or more hydroprocessing reactors configured to hydroprocessing heavy oils comprises one or more ebullated bed reactors utilizing the first dispersed metal sulfide catalyst particles in combination with a heterogeneous ebullated bed catalyst.

26. The system of claim 24 or 25, wherein the one or more hydroprocessing reactors configured to hydrotreat deasphalted oil comprises one or more ebullated bed reactors utilizing the second dispersed metal sulfide catalyst particles in combination with a heterogeneous ebullated bed catalyst.

27. The system of any of claims 24-26, further comprising one or more separators selected from a flash separator, a thermal separator, an atmospheric distillation column, or a vacuum distillation column and configured to separate the upgraded heavy oil into one or more lower boiling hydrocarbon fractions and one or more liquid hydrocarbon fractions.

28. The system of claim 27, wherein solvent deasphalting comprises:

an extractor unit configured to receive at least a portion of the one or more liquid hydrocarbon fractions and the solvent and to perform solvent deasphalting;

a flash separator configured to receive a first stream containing deasphalted oil (DAO) and a first portion of solvent removed from the extractor unit, followed by a DAO vacuum stripper configured to produce deasphalted oil and a first recovered solvent;

a heater configured to receive a second stream containing bitumen and a second portion of solvent removed from the extractor, followed by a flash separator unit, followed by a bitumen vacuum stripper configured to produce bitumen and a second recovered solvent; and

means for recycling at least a portion of the first recovered solvent and the second recovered solvent to the extractor, optionally with make-up solvent.

29. The system of any of claims 24 to 28, further comprising means for recycling at least a portion of the bitumen by adding the at least a portion of the bitumen to the hydrotreated heavy oil, and further providing additional dispersed metal sulfide catalyst particles in addition to the first dispersed metal sulfide catalyst particles.