Patent Application
20240018424
The present technology relates to processes for reducing sulfur and asphaltene content in hydrocarbon feedstocks as well as other impurities to improve performance of downstream oil conversion processes. Both catalytic and thermal conversion performance may be improved.
Hydrocarbon oils, including many oil feedstocks, often contain difficult-to-remove impurities such as sulfur in the form of organosulfur compounds as well as metals and other heteroatom-containing compounds that hinder usage of the hydrocarbons. The undesired impurities present in hydrocarbon oils can be concentrated in the resins and asphaltenes found in the vacuum residue distillation fraction, generally defined by a boiling point of 510° C. to 565° C. (950° F. to 1050° F.) or greater. Traditional refining configurations further concentrate the undesired impurities by separating the high value, low boiling point distillation fractions (gasoline, diesel, jet, and gasoils) from the low value, high boiling point bottoms fractions (atmospheric and vacuum residues). The low boiling point distillation fractions can be easily treated and converted into finished products using established processes such as hydrotreating, alkylation, catalytic reforming, catalytic cracking and the like. High boiling point residuum streams cannot be easily treated because the disproportionately high metals content fouls catalysts and the polyaromatic structure of the asphaltenes hinders access to impurities.
The sulfur species present in hydrocarbons can be characterized as asphaltenic sulfur (i.e., sulfur-containing asphaltene species) and non-asphaltenic sulfur (i.e., sulfur-containing non-asphaltene species). Non-asphaltenic sulfur typically includes thiols, sulfides, benzothiophene and dibenzothiophene (DBT) derivatives among others, is primarily located in the vacuum residuum fraction, but may also be present in the saturates, aromatics and resin components located in any distillation fraction. These sulfur species, especially those located within the gasoline, naphtha, kerosene, diesel, and gasoil fractions, can generally be removed using conventional catalytic treatment or conversion processes such as hydrotreating, hydrodesulfurization or hydrocracking. Asphaltenic sulfur, located in the asphaltenes within the heaviest residuum distillation fraction, is primarily characterized by layers of condensed, sulfur-containing polynuclear aromatic compounds linked by saturated species and sulfur. DBT and DBT derivatives and sulfur bridges may account for a large proportion of the asphaltenic sulfur species. Additionally, metals, including nickel, vanadium and iron, are often concentrated within porphyrin metal complexes located in the asphaltene fraction. Sulfur cannot be easily removed from asphaltenes without subjecting the asphaltenic sulfur to severe operating conditions.
Residuum thermal or catalytic conversion units operate under severe operating conditions, typically high temperatures (>350° C./662° F.), high hydrogen partial pressures (500-3000 psig) and with specialized catalysts that are deactivated by metals and coke deposition. Even after subjecting the residuum streams to the most severe operating conditions, a fraction of sulfur and metals is not removed and remains in the oil. As a result, low value residuum bottoms streams are either 1) converted into asphalt, 2) processed in a thermal conversion unit (like a coker) to extract as many high value intermediates as possible or 3) blended into high sulfur bunker fuel.
Surprisingly, processes for preferentially removing the sulfur and metals from sulfur-containing asphaltenes and/or converting a portion of the asphaltene fraction in hydrocarbon feedstocks into non-asphaltene liquid products have been discovered. The processes provide a converted feedstock with a reduced sulfur (and other heteroatom) content and a reduced metals content, especially within the asphaltene fraction. Using the present technology, impurities concentrated in an asphaltene fraction of a hydrocarbon feedstock may be best removed by contacting such feeds with sodium metal while impurities concentrated elsewhere may be best removed by traditional refining processes. Furthermore, the operation of downstream process units may be optimized by reducing the high concentration of impurities within the asphaltene fraction, resulting in improved refinery operability and profitability.
Thus, in a first aspect, the present technology provides a process for improving the yield of liquid hydrocarbons from a thermal conversion process comprising: contacting a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250-500° C., to produce a mixture of sodium salts and a converted feedstock, wherein the hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt % and micro carbon residue content of at least 5 wt %; the converted feedstock comprises hydrocarbons with a sulfur content less than that in the hydrocarbon feedstock, a micro carbon residue content less than that in the hydrocarbon feedstock and/or an asphaltene content less than that in the hydrocarbon feedstock; and subjecting the converted feedstock to a thermal conversion process to produce a gaseous product, a purified product and a residual product, wherein the proportion of purified product to residual product is greater than that produced by subjecting the hydrocarbon feedstock to the same thermal conversion process. In embodiments where the thermal conversion process is, e.g., a coking process, the present process provides improved yield of vacuum gasoil, reduced coke losses, and lowers sulfur content of all subsequent streams. The lower sulfur content translates into less H2S to be handled by, e.g., a Claus plant, lower loads for gasoil hydrotreaters and sweeter coke. Moreover, the amount of sodium metal used in the process can be varied to optimize downstream yields and economics.
In a second aspect, the present technology provides a process for preparing anode grade coke from dirtier feeds than previously possible. The process comprises: contacting a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250-500° C., to produce a mixture of sodium salts and a converted feedstock, wherein the hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt %, a vanadium content of at least 15 ppm and a micro carbon residue content of at least 5 wt %; the converted feedstock comprises hydrocarbons with a sulfur content less than that in the hydrocarbon feedstock, micro carbon residue less than that in the hydrocarbon feedstock and/or an asphaltene content less than that in the hydrocarbon feedstock; and subjecting the converted feedstock to a thermal conversion process to produce a premium anode grade coke product with less than 0.5% wt % sulfur and less than 150 ppm vanadium.
In a third aspect, the present technology provides a process for preparing needle grade coke from dirtier feeds than previously possible. The process comprises: contacting a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250° C.-500° C., to produce a mixture of sodium salts and a converted feedstock, wherein the hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt %, a nickel content of at least 10 ppm and a micro carbon residue content of at least 5 wt %; the converted feedstock comprises hydrocarbons with a sulfur content less than that in the hydrocarbon feedstock, micro carbon residue less than that in the hydrocarbon feedstock and/or an asphaltene content less than that in the hydrocarbon feedstock; and subjecting the converted feedstock to a thermal conversion process to produce a high purity needle coke product with less than 0.5 wt % sulfur, less than 0.7 wt % nitrogen, less than 10 ppm nickel, a coefficient of thermal expansion greater than 2.5×107/° C. and an electrical resistivity of 320×106 Ohm-In.
In a fourth aspect, the present technology provides a process for improving the conversion of a hydrocarbon feedstock in catalytic conversion processes. The process comprises: combining a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250° C.-500° C., to produce a mixture of sodium salts and a converted feedstock, wherein the hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt % and a total metal content of at least 100 ppm; the converted feedstock comprises a hydrocarbon having a sulfur content less than 0.5 wt %, a vanadium content less than 50 ppm, a nickel content less than 50 ppm, a lower concentration of asphaltenes than that in the hydrocarbon feedstock, and/or a greater proportion of lower boiling point hydrocarbons (<538° C.) to residual hydrocarbons (>538° C.) than that in the hydrocarbon feedstock; optionally subjecting the converted feedstock to a thermal conversion process to provide a double-converted product; and subjecting the converted feedstock or double-converted feedstock to a catalytic conversion process (e.g., catalytic hydroprocessing) to produce a fuel grade product without blending or further conversion processing. This process improves conversion and performance of hydrocarbon feeds, including residual streams, in downstream catalytic processing by a) improving catalyst life, b) providing higher gasoline yield, and c) allowing the coker to be bypassed completely.
In a fifth aspect, the present technology provides a process for producing a low sulfur fuel-grade product from an out-of-specification hydrocarbon feedstock with little or no blending. The process comprises: combining a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250° C.-500° C., to produce a mixture of sodium salts and a converted feedstock, wherein the hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt % and fails to meet one or more fuel-grade specifications selected from the group consisting of viscosity, density, micro carbon residue, metals content and cleanliness/compatibility; the converted product comprises a hydrocarbon having a sulfur content less than 0.5 wt %, and meets one or more fuel grade specifications selected from the group consisting of viscosity, density, micro carbon residue, metals content and compatibility; and the fuel-grade specifications are viscosity of less than 380 cSt @ 50 C, a density of less than 991 kg/m3, a micro carbon residue content less than 18 wt %, a vanadium content less than 350 mg/kg and a cleanliness spot test result of 1 or 2 as measured by ASTM D4740. For example, low sulfur bunker fuel may be prepared via the disclosed method. In some embodiments, the product is a near fuel grade product that may be brought up to specification by blending a nominal amount of blendstock, e.g., blending 0.5 wt %-10 wt %.
The foregoing is a summary of the disclosure and thus by necessity contains simplifications, generalizations, and omissions of detail. Consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, features, and advantages of the processes described herein, as defined by the claims, will become apparent in the detailed description set forth herein and taken in conjunction with the accompanying drawings.
In order that the manner in which the above-recited and other features and advantages of the technology are obtained will be readily understood, a more particular description of the technology briefly described above will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the technology and are not therefore to be considered to be limiting of its scope, the technology will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
The following terms are used throughout as defined below.
As used herein, singular articles such as “a” and “an” and “the” and similar referents in the context of describing the elements (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the embodiments and does not pose a limitation on the scope of the claims unless otherwise stated. No language in the specification should be construed as indicating any non-claimed element as essential.
As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term.
As used herein, “asphaltenes” refers to the constituents of oil that are insoluble in any of the C3-8 alkanes. Asphaltenes include polyaromatic molecules that comprise one or more heteroatoms selected from S, N, and O. Sulfur species found in asphaltenes are collectively referred to herein as “asphaltenic sulfur.” All other sulfur species found in the non-asphaltenic fractions of hydrocarbon oils and fractions thereof, are collectively referred to herein as “non-asphaltenic sulfur.” The latter may include, e.g., thiols, sulfates, thiophenes, including benzothiophenes and dibenzothiophenes, hydrogen sulfide and other sulfides.
As used herein, “hydrocarbon feedstocks” refers to any material that may be an input for refining, conversion or other industrial process in which hydrocarbons are the principal constituents. Hydrocarbon feedstocks may be solid or liquid at room temperature and may include non-hydrocarbon constituents such as heteroatom-containing (e.g., S, N, O, P, metals) organic and inorganic materials. Crude oils, refinery streams, chemical plant streams (e.g. steam cracked tar) and recycling plant streams (e.g., lube oils and pyrolysis oil from tires or municipal solid waste) are non-limiting examples of hydrocarbon feedstocks.
The present technology provides processes for improving the yield of downstream oil conversion processes. Thus, in a first aspect is provided a process for improving the yield of liquid hydrocarbons from a thermal conversion process comprising: contacting a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250-500° C., to produce a mixture of sodium salts and a converted feedstock. The hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt % and micro carbon residue content of at least 5 wt %. The converted feedstock comprises hydrocarbons with a sulfur content less than that in the hydrocarbon feedstock, a micro carbon residue content less than that in the hydrocarbon feedstock and/or an asphaltene content less than that in the hydrocarbon feedstock. Micro carbon residue (MCR), measured according to ASTM D4530, indicates the tendency of a hydrocarbon to form carbonaceous deposits after exposure to high temperatures. MCR is numerically equivalent to the Conradson carbon residue (CCR), measured according to ASTM D189, and may be used interchangeably. In any embodiments, the converted feedstock comprises hydrocarbons with a sulfur content less than that in the hydrocarbon feedstock, a micro carbon residue content less than that in the hydrocarbon feedstock and an asphaltene content less than that in the hydrocarbon feedstock. The converted feedstock is subjected to a thermal conversion process (e.g., a coking or visbreaking process) to produce a gaseous product (e.g., steam, H2S, C1-C4 saturated gases, C2-C4 olefins and isobutane), a purified product (e.g., naphtha, diesel, gasoils and light and heavy cycle oils) and a residual product (e.g., coke or visbreaker tar), wherein the proportion of purified product to residual product is greater than that produced by subjecting the hydrocarbon feedstock to the same thermal conversion process.
In a second aspect, a process for producing premium anode grade coke or needle coke is provided. The process includes contacting a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250-500° C., to produce a mixture of sodium salts and a converted feedstock. The hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt %, a vanadium content of at least 15 ppm and a micro carbon residue content of at least 5 wt %. The converted feedstock comprises hydrocarbons with a sulfur content less than that in the hydrocarbon feedstock, micro carbon residue less than that in the hydrocarbon feedstock and/or an asphaltene content less than that in the hydrocarbon feedstock. In any embodiments, the converted feedstock comprises hydrocarbons with a sulfur content less than that in the hydrocarbon feedstock, micro carbon residue less than that in the hydrocarbon feedstock and an asphaltene content less than that in the hydrocarbon feedstock. The converted feedstock is subjected to a thermal conversion process to produce a premium anode grade coke product with less than 0.5% wt % sulfur and less than 150 ppm vanadium.
In a third aspect, there is provided a process for producing needle coke, comprising contacting a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250° C.-500° C., to produce a mixture of sodium salts and a converted feedstock. The hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt %, a nickel content of at least 10 ppm and a micro carbon residue content of at least 5 wt %; the converted feedstock comprises hydrocarbons with a sulfur content less than 0.5 wt %, micro carbon residue less than that in the hydrocarbon feedstock, an asphaltene content less than 0.25 wt % and/or ash content <0.1 wt %. In any embodiments, the converted feedstock comprises hydrocarbons with a sulfur content less than 0.5 wt %, micro carbon residue less than that in the hydrocarbon feedstock, an asphaltene content less than 0.25 wt %/o and ash content <0.1 wt %. The converted feedstock is treated in a thermal conversion process to produce a high purity needle coke product with less than 0.5 wt % sulfur, less than 0.7 wt % nitrogen, less than 10 ppm nickel, a coefficient of thermal expansion greater than 2.5×107/° C. and an electrical resistivity of 320×106 Ohm-In.
In a fourth aspect, the present technology provides processes for improving the conversion of feedstocks in a catalytic conversion or a treatment process. The process may include: combining a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250° C.-500° C., to produce a mixture of sodium salts and a converted feedstock; optionally further subjecting the converted feedstock to a thermal conversion process to provide a double-converted product; and subjecting the converted feedstock or double-converted feedstock to a catalytic conversion process (e.g., catalytic hydroprocessing, fluid catalytic cracking, etc.) to produce a fuel grade product without blending or further conversion processing. In this process, the hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt % and a total metal content of at least 100 ppm. The converted feedstock comprises a hydrocarbon having a sulfur content less than 0.5 wt %, a vanadium content less than 50 ppm, a nickel content less than 50 ppm, a lower concentration of asphaltenes than that in the hydrocarbon feedstock, and/or a greater proportion of lower boiling point hydrocarbons (<538° C.) to residual hydrocarbons (>538° C.) than that in the hydrocarbon feedstock. In any embodiments, the converted feedstock comprises a hydrocarbon having a sulfur content less than 0.5 wt %, a vanadium content less than 50 ppm, a nickel content less than 50 ppm, a lower concentration of asphaltenes than that in the hydrocarbon feedstock, and a greater proportion of lower boiling point hydrocarbons (<538° C.) to residual hydrocarbons (>538° C.) than that in the hydrocarbon feedstock.
In the fourth aspect, when the converted feedstock has a micro carbon residue content of at least 5 wt %, the process may further include subjecting the converted feedstock to a thermal conversion process (e.g., in a coker) to provide the double-converted feedstock and a solid coke product. In such embodiments, the double-converted product comprises a liquid hydrocarbon having a lower concentration of impurities than that in the hydrocarbon feedstock, and a proportion of lower boiling point hydrocarbons (<538° C.) to higher boiling point residuum hydrocarbons (>538° C.) greater than that of the converted feedstock. In any embodiments of the fourth aspect, the fuel grade product may be gasoline, diesel, kerosene, jet fuel, petroleum naphtha, or LPG.
In a fifth aspect, the present technology provides processes for producing low sulfur fuel-grade products. The processes include combining a hydrocarbon feedstock with an effective amount of sodium metal and an effective amount of exogenous capping agent at a temperature of 250° C.-500° C., to produce a mixture of sodium salts and a converted feedstock. The hydrocarbon feedstock comprises hydrocarbons with a sulfur content of at least 0.5 wt %, an asphaltene content of at least 1 wt % and fails to meet one or more fuel-grade specifications selected from the group consisting of viscosity, density, micro carbon residue, metals content and cleanliness/compatibility. The converted product comprises a hydrocarbon having a sulfur content less than 0.5 wt %, and meets one or more fuel grade specifications selected from the group consisting of viscosity, density, micro carbon residue, metals content and compatibility, wherein the fuel-grade specifications are viscosity of less than 380 cSt @ 50 C, a density of less than 991 kg/m3, a micro carbon residue content less than 18 wt %, a vanadium content less than 350 mg/kg and a cleanliness spot test result of 1 or 2 as measured by ASTM D4740. In some embodiments, the converted product meets two or more, three or more, four or more or all five fuel grade specifications. In some embodiments, the product is a near fuel grade product that may be brought up to specification by blending a nominal amount of blendstock, e.g., blending 0.5 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, or 10 wt %, or a range between and including any two of the foregoing values such as 0.5-10 wt %, 1-10 wt % or 2-7 wt %.
In any embodiments of the processes described herein, the processes may further include pretreating the hydrocarbon feedstock before the contacting step to provide a purified feedstock and a pretreated hydrocarbon feedstock. The purified feedstock comprises a lower concentration of impurities than the hydrocarbon feedstock before pretreatment, the pretreated hydrocarbon feedstock comprises a higher concentration of impurities than the purified feedstock; and the pretreated hydrocarbon feedstock is the feedstock subjected to the contacting step to produce the converted feedstock. In any embodiments of the present processes including a pretreating step, the pretreatment step may include phase separation by an externally applied field, separation by addition of heat, hydroconversion, thermal conversion, catalytic conversion or treatment, solvent extraction, solvent deasphalting or a combination of any two or more thereof. In any embodiments, the pretreatment step may include contacting the hydrocarbon feedstock with exogenous hydrogen and/or a catalyst to remove one or more of sulfur, nitrogen, oxygen, metals and asphaltenes. Examples of pretreatment steps to produce a purified feedstock and a pretreated hydrocarbon feedstock include atmospheric distillation, vacuum distillation, steam cracking, catalytic cracking, thermal cracking, fluid catalytic cracking (FCC), solvent deasphalting, hydrodesulfurization, visbreaking, pyrolysis, catalytic reforming, alkylation, and combinations of any two or more of the foregoing. It will be understood that certain of the foregoing processes, such as atmospheric distillation and vacuum distillation directly yield a purified feedstock and a pretreated hydrocarbon feedstock, while others require a subsequent separation step. For example, steam cracking, catalytic cracking, thermal cracking, FCC and pyrolysis yield a mixture of products that can be subsequently separated into a purified feedstock and a pretreated hydrocarbon feedstock by distillation or other separation process.
In any aspects or embodiments of the processes described herein including a thermal conversion process, the thermal conversion process may be or include visbreaking, delayed coking, fluid coking, Flexicoking™, pyrolysis, a variant thereof or a combination of any two or more thereof. In any embodiments, the thermal conversion process may be operated at a temperature about 400° C. to about 570° C. In any embodiments, the thermal conversion process may be operated at a pressure of about 10 to about 200 psig. In any embodiments, the thermal conversion process may be operated at about 450° C. to about 500° C. and at about 20-100 psig, e.g., as in a coker.
In any aspects or embodiments of the processes described herein including a catalytic conversion process, the catalytic conversion process comprises fluid catalytic cracking (FCC), residual FCC, hydrotreating, residual hydrotreating, hydrocracking, catalytic reforming, hydrodesulfurization, hydrodenitrogenation, hydrodemetallation, or residue upgrading/hydroconversion (e.g., ARDS®, LC-Fining®, H-Oil®), their variants or a combination of any two or more thereof. The catalyst may comprise cobalt, molybdenum, nickel, tungsten, platinum, palladium, alumina, silica, zeolites, their isomers, oxides, sulfides or combinations of any two or more thereof. In any embodiments, the catalytic conversion process may be operated at a temperature from about 250° C. to about 575° C. In any embodiments, the catalytic conversion process may be operated at a pressure of about 10 to about 3000 psig. In any embodiments, the catalytic conversion process may be operated at about 400° C. to about 575° C. and at about 1000 to about 3000 psig. In any embodiments, the catalytic conversion process may be operated at about 450° C. to about 575° C. and at about 15 to about 100 psig.
In any aspects or embodiments of the processes described herein, it will be understood that other refinery processes such as distillation (both atmospheric or vacuum distillation) may be employed as part of the process. Alternatively, in certain aspects or embodiments, other refinery processes may be used in place of thermal or catalytic conversion processes (see, e.g.,
Hydrocarbon feedstocks for the present processes are or may be derived from virgin crude oils (for example petroleum, heavy oil, bitumen, shale oil and oil shale). Hydrocarbon feedstocks may also be a residual feedstock, e.g., the product of a thermal cracking process. Residual feedstocks may be produced by various pretreatment processes of the present technology and will be referred to as “pretreated hydrocarbon feedstocks,” which may also be contacted with sodium metal and exogenous capping agent. Thus, pretreated feedstocks may include distillation products of hydrocarbon feedstocks, (atmospheric or vacuum residuums, gasoline, diesel, kerosene, and gas oils), and refinery intermediate streams. In any embodiments, the pretreated hydrocarbon feedstock may include hydrotreated products, hydrocracker residue, hydroconversion residue (e.g., LC-Finer® (Chevron Global Lummus) residue, or H-Oil® (Axens) residue), FCC slurry, residual FCC slurry, atmospheric or vacuum residuums, solvent deasphalting tar, deasphalted oil, steam cracked tar, visbreaker tar, high sulfur fuel oil, low sulfur fuel oil, asphaltenes, asphalt and coke. The foregoing hydrocarbon feedstocks (including pretreated hydrocarbon feedstocks) may be derived from any geological formation (oil sand, conventional or tight reservoirs, shale oil, oil shale) or geographical location (North America, South America, Middle East, etc.). In certain aspects and embodiments of the present processes, especially the second and third aspects, the hydrocarbon feedstock includes a significant amount of aromatic compounds, e.g., at least 10 wt %, at least 20 wt %, at least 25 wt %, at least 30 wt %,
In processes of the present technology, the hydrocarbon feedstock includes hydrocarbons (e.g., a hydrocarbon oil) and impurities. Similarly, the residual feedstock includes hydrocarbons and impurities. In some embodiments, the residual feedstock has a higher concentration of impurities than the hydrocarbon feedstock. “Impurities” as used herein refer to heteroatoms (i.e., atoms other than carbon and hydrogen), such as sulfur, oxygen, nitrogen, phosphorous, and metals. Impurities may be found in or include substances such as naphthenic acids, water, ammonia, hydrogen sulfide, thiols, thiophenes, benzothiophenes, porphyrins, Fe, V, Ni, and the like. In any embodiments of the present processes, the hydrocarbon feedstock or residual feedstock includes hydrocarbons with a sulfur content of at least 0.5 wt % and an asphaltene content of at least 1 wt %. The sulfur content comprises asphaltenic sulfur and non-asphaltenic sulfur, but is measured as the wt % of sulfur atoms in the feedstock. In any embodiments, the sulfur content may range from 0.5 wt % to 15 wt %, including for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 wt % or a range between and including any two of the foregoing values. Thus, the sulfur content may range may be, in any embodiments, 1 wt % to 15 wt %, 0.5 wt % to 8 wt %, or 1.5 wt % to 10 wt %.
In processes of the present technology, the asphaltene content refers to the total amount of asphaltenes in a feedstock measured as the n-pentane insoluble fraction of the feedstock. However, in some aspects or embodiments of the present processes, the asphaltene content may be measured as the insoluble fraction precipitated or otherwise separated from the feedstock, after mixing with a sufficient quantity of one or more C3-8 alkanes. The C3-8 alkanes may be propane, butane, pentane, hexane, heptane, octane, isomers thereof, or mixtures of any two or more thereof. In any embodiments, the asphaltene content of a feed may be defined as the constituents insoluble in heptane. A detailed discussion of the physical properties and structure of asphaltenes and the process conditions (temperatures, pressures, solvent/oil ratios) required to produce a specific asphaltene is described in J. G. Speight, “Petroleum Asphaltenes Part 1: Asphaltenes, Resins and the Structure of Petroleum”, Oil & Gas Science and Technology—Rev IFP, Vol 59 (2004) pp. 467-477 (incorporated herein by reference in its entirety and for all purposes). The standard test method for determining heptane (C7) insoluble asphaltene content is described by ASTM standard D6560-17 and can be extended to any alkane, including pentane.
In any embodiments of the present processes, the asphaltene content of hydrocarbon feedstock or residual feedstock may be at least 1 wt %, at least 2 wt %, at least 3 wt %, at least 4 wt % or at least 5 wt %. For example, the asphaltene content may range from 1 wt % to 100 wt %, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 95 or 100 wt % or between and including any two of the foregoing values. Thus, in any embodiments, the asphaltene content may range from 2 wt % to 100 wt %, 1 wt % to 30 wt %, 2 wt % to 30 wt %, 5 wt % to 100 wt %, 10 wt % to 100 wt %, or 20 wt % to 100 wt %.
In any embodiments of the present process, it may be necessary to dilute the hydrocarbon feedstock with a diluent if an elevated asphaltene content in the hydrocarbon feedstock leads to a viscosity that is too high for the sodium treatment process. Because of the aromatic nature of asphaltenes, a diluent will typically include aromatics (i.e., compounds having aromatic rings). The diluent may be a single compound (e.g., benzene, toluene, xylene, ethylbenzene, cumene, naphthalene, 1-methylnaphthalene), mixtures of any two or more thereof, or a refinery intermediate that is aromatic (e.g., light cycle oil, reformate). The amount of diluent needed will vary with the asphaltene content of the feedstock and the viscosity required for processing. Higher asphaltene content in a feedstock may require more diluent than a feedstock with lower asphaltene content. It is within the skill in the art to select an appropriate amount of diluent to permit processing of asphaltenes in the present processes.
The present processes may also reduce/remove the naphthenic acid content and/or the metals content in converted feedstocks compared to the hydrocarbon and pretreated hydrocarbon feedstocks. In any embodiments the hydrocarbon feedstock or pretreated hydrocarbon feedstock includes (on an aggregate or individual basis) about 1 to about 10,000 ppm metals. The metals may be naturally occurring metals bound to the hydrocarbon structure or residual metal fragments entrained in the pretreated hydrocarbon feedstock during upstream processing (e.g., corrosion products or catalyst fragments). In any embodiments, the metal is selected from the group consisting alkali metals, alkali earth metals, transition metals, post transition metals, and metalloids having an atomic weight equal to or less than 82. In any embodiments, the metal is selected from the group of vanadium, nickel, iron, arsenic, lead, cadmium, copper, zinc, chromium, molybdenum, silicon, calcium, potassium, aluminum, magnesium, manganese, titanium, mercury and combinations of any two or more thereof. In any embodiments, the metal is selected from the group consisting of vanadium, nickel, iron, and combinations of any two or more thereof. In any embodiments, the metals concentration of the hydrocarbon feedstock or the pretreated hydrocarbon feedstock may be (in the aggregate or on an individual basis) about 2 to about 10,000 ppm, about 10 to about 10,000 ppm, about 100 to about 10,000 ppm, about 100 to about 5,000 ppm, about 10 to about 1,000 ppm, about 100 to about 1,000 ppm, and the like.
The processes of the present technology not only upgrade the hydrocarbon and pretreated hydrocarbon feedstocks employed by removal/reduction of impurities, but may also improve physical properties such as viscosity and density. The hydrocarbon feedstock or pretreated hydrocarbon feedstock may have a viscosity between 1 to 10,000,000 cSt at 50° C. For example, the viscosity may 1, 10, 25, 50, 100, 200, 300, 400, 500, 1,000, 2,000, 5,000, 10,000, 25,000, 50,000, 100,000, 500,000, 1,000,000, 2,000,000, 3,000,000, 4,000,000, 5,000,000, 6,000,000, 7,000,000, 8,000,000, or 9,000,000 cSt or a range between and including any two of the foregoing values. Thus, in any embodiments, the viscosity of the hydrocarbon feedstock or the pretreated hydrocarbon feedstock may be, e.g., 100 to 10,000,000 cSt, 380 to 9,000,000 cSt, 500 to 9,000,000 cSt, or 500 to 5,000,000 cSt, among others.
The hydrocarbon feedstock or pretreated hydrocarbon feedstock may a density from 800 to 1200 kg/m3 at 15.6° C. or 60° F. For example, the density may be 800, 825, 850, 875, 900, 925, 975, 1000, 1050, 1100, 1150, or 1200 kg/m3 or a range between and including any two of the foregoing values. Thus, in any embodiments, the density may be, e.g., from 850 to 1200 kg/m3, 900 to 1200 kg/m3, 950 to 1200 kg/m3, or 925 to 1100 kg/m3.
In processes of the present technology, the hydrocarbon feedstock or pretreated hydrocarbon feedstock is contacted with an effective amount of sodium metal and an effective amount of exogenous capping agent. Any suitable source of sodium metal may be used, including, but not limited to electrochemically generated sodium metal, e.g., as described in U.S. Pat. No. 8,088,270, incorporated by reference in its entirety herein. By “effective amount” is meant the amount of a material or agent to bring about a desired consequence. For example, an effective amount of sodium metal in the present processes may include a stoichiometric, suprastoichiometric or substochiometric amount of sodium metal sufficient to reduce the amount of asphaltene and/or sulfur in the hydrocarbon feedstock.
The exogenous capping agent used in the present processes is typically used to cap the radicals formed when sulfur and other heteroatoms have been abstracted by the sodium metal during the contacting step. Although some feedstocks may inherently contain small amounts of naturally occurring capping agents (“endogenous capping agents”), such amounts are insufficient to cap substantially all of the free radicals generated by the present processes. Effective amounts of exogenous (i.e., added) capping agents are used in the present processes, such as 1-1.5 moles of capping agent (e.g., hydrogen) may be used per mole of sulfur, nitrogen, or oxygen present. It is within the skill of the art to determine an effective amount of exogenous capping agent needed to carry out the present processes for the particular hydrocarbon feedstock or pretreated hydrocarbon feedstock being used based on the disclosure herein. The exogenous capping agent may include hydrogen, hydrogen sulfide, natural gas, methane, ethane, propane, butane, pentane, ethene, propene, butene, pentene, dienes, isomers of the forgoing, or a mixture of any two or more thereof. In any embodiments, the exogenous capping agent may be hydrogen and/or a C1-6 acyclic alkanes and/or C2-6 acyclic alkene or a mixture of any two or more thereof.
The effective amount of sodium in its metallic state and used in the contacting step will vary with the level of heteroatom, metal, and asphaltene impurities of the hydrocarbon and pretreated hydrocarbon feedstocks, the desired extent of conversion or removal of an impurity, the temperature used and other conditions. In any embodiments, stoichiometric or greater than stoichiometric amounts of sodium metal may be used to remove all or nearly all sulfur content, e.g., 1-3 mole equivalents of sodium metal versus sulfur content. In any embodiments, the hydrocarbon feedstock or pretreated hydrocarbon feedstock is contacted with more than 1 mole equivalent of sodium metal versus the sulfur content therein, e.g., 1.1, 1.15, 1.2, 1.25, 1.3, 1.4, 1.5, 2, 2.5 or 3 mole equivalents of sodium metal.
Surprisingly, a sub-stoichiometric ratio of metallic sodium to sulfur content (in the hydrocarbon/pretreated hydrocarbon feedstocks) may be used to preferentially lower the amount of asphaltenic sulfur versus the non-asphaltenic sulfur. Thus, in any embodiments, the pretreated hydrocarbon feedstock (or alternatively the hydrocarbon feedstock) may be contacted with a less than stoichiometric amount of sodium metal to the sulfur content therein. In the present technology, it will be understood that the stoichiometric amount of sodium metal to sulfur content is the theoretical amount of sodium metal required to convert all sulfur content in the pretreated hydrocarbon (or hydrocarbon) feedstock to sodium sulfide. For example, it will be appreciated by those of skill in the art that the stoichiometric amount of sodium metal necessary to convert all of the sulfur to sodium sulfide in a feedstock containing about 1 mole of sulfur atoms is 2 moles of sodium metal. A less than stoichiometric amount of sodium metal to sulfur content in such an example would be less than 2 moles of sodium metal, such as 1.6 moles, or 0.8 mole equivalents of sodium metal. In any embodiments, the less than stoichiometric amount of sodium metal to sulfur content may be 0.1 equivalents to less than 1 equivalent. Examples of such sub-stoichiometric amounts include 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or less than 1 equivalents of sodium metal to sulfur content or a range between and including any two of the foregoing values. Thus, in any embodiments the sub-stoichiometric amounts may range from 0.1 to 0.9 equivalents, 0.2 to 0.8 equivalents, 0.4 to 0.8 equivalents, or the like.
As the contacting step takes place at a temperature of about 250° C. to about 500° C., the sodium metal will be in a molten (i.e., liquid) state. For example the contacting step may be carried out at about 250° C., about 275° C., about 300° C., about 325° C., about 350° C., about 375° C., about 400° C., about 425° C., about 450° C., about 500° C., or a range between and including any two of the foregoing temperatures. Thus, in any embodiments the contacting may take place at about 275° C. to about 425° C., or about 300° C. to about 400° C. (e.g., at about 350° C.).
In any embodiments, the contacting step may take place at a pressure of about 400 to about 3000 psi, e.g., at about 400 psi, about 500 psi, about 600 psi, about 750 psi, about 1000 psi, about 1250 psi, about 1500 psi, about 2000 psi, about 2500 psi, about 3000 psi or a range between and including any two of the foregoing values.
The reaction of sodium metal with heteroatom contaminants in the hydrocarbon/pretreated hydrocarbon feedstocks is relatively fast, being complete within a few minutes, if not seconds. Mixing the combination of feedstock and metallic sodium further speeds the reaction and is commonly used for this reaction on the industrial scale. However, certain embodiments may require an extended residence time to improve the extent of conversion or adjust the operating conditions to target removal of a specific heteroatom impurity. Hence, in any embodiments the contacting step is carried out for about 1 minute to about 120 minutes, e.g., about 1, about 5, about 7, about 9, about 10, about 15 minutes, about 30, about 45 about 60, about 75, about 90, about 105, or about 120 minutes, or is conducted for a time ranging between and including any two of the foregoing values. Thus, in any embodiments the time may range from about 1 to about 60 minutes, about 5 minutes to about 60 minutes, about 1 to about 15 minutes, about 60 minutes to 120 minutes, or the like.
The present processes produce a converted feedstock that include a hydrocarbon oil with a sulfur content less than that in the hydrocarbon feedstock (or pretreated hydrocarbon feedstock). In any embodiments, the sulfur content of the converted feedstock may be less than 0.5 wt %, e.g., less than or about 0.4 wt %, less than or about 0.3 wt %, less than or about 0.2 wt %, less than or about 0.1 wt %, and even less than or about 0.05 wt %, or a range between and including any two of the foregoing values. Removal efficiency of the sulfur content (a.k.a., conversion efficiency) from the hydrocarbon or pretreated hydrocarbon feedstock compared to the converted feedstock may be at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% by weight, or a range between and including any two of the foregoing values. Where the effective amount of sodium metal is greater than a stoichiometric amount, the sulfur content conversion efficiency can be very high, e.g., at least 90%.
When sub-stoichiometric amounts of sodium metal are used in the present processes (including but not limited to processes of the first, second, third and fourth aspects), lower conversion efficiencies are observed, but the sulfur content from asphaltenic sulfur is preferentially reduced compared to that from non-asphaltenic sulfur. For example, the (total) sulfur content conversion efficiency may range from about 10% to about 80%, including, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or a range between and including any two of the foregoing values. At the same time, the corresponding sulfur content conversion efficiency of asphaltenic sulfur is higher at each point than the total sulfur-conversion efficiency. For example sulfur content conversion efficiency of asphaltenic sulfur for any given feed may range from 1% to 40% higher (e.g., 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 22%, 24%, 25%, 27%, 30%, 32%, 35%, 37%, or 40% higher or a range between and including any two of the foregoing values) than the corresponding overall sulfur content conversion efficiency.
The converted feedstocks of the present technology have a reduced concentration of metals compared to the hydrocarbon or pretreated hydrocarbon feedstocks. The metals content of the converted feedstock may be reduced by at least 20% compared to the hydrocarbon feedstock or pretreated hydrocarbon feedstock, for example, by 20% to 100%. Examples of the percent reduction in metals (collectively or individually) in the converted feedstock compared to the hydrocarbon feedstock or the pretreated hydrocarbon feedstock include 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 97%, 98%, 99%, 100%, or a range between and including any two or more of the foregoing values. Thus, in any embodiments the percent reduction may be from 20% to 99%, from 20% to 95%, from 70% to 99% or to 100%. The metals may be any of those disclosed herein. In some embodiments, the metals are selected from iron, vanadium, nickel or combinations of any two or more thereof. For example, the iron and vanadium content of the converted feedstock has been reduced by at least 20% compared to the hydrocarbon feedstock or pretreated hydrocarbon feedstock. Similarly, in any embodiments, the nickel content of the converted feedstock has been reduced by at least 20% compared to the hydrocarbon feedstock or pretreated hydrocarbon feedstock.
The present processes also provide converted feedstocks with improved physical properties compared to the hydrocarbon feedstock or pretreated hydrocarbon feedstock. However, it has been discovered that the physical properties of converted feedstocks of the present processes do not necessarily change proportionately to the sodium to sulfur ratio. For example, the extent of metals demetallization, especially metals detrimental to catalyst life including iron, vanadium and nickel will generally be greater than the extent of desulfurization for a given sodium to sulfur ratio. Example 6 demonstrates the insensitivity of sodium treatment to initial metals content, unlike catalytic conversion processes. Sodium demetallization at low sodium/total sulfur addition ratio could be highly advantageous for pre-treating a hydrocarbon feed with an undesirably high metals content prior to catalytic conversion or treatment.
Additional physical properties that greatly reduce the value of heavy residual feedstocks are improved after treatment with sodium. Desulfurization of the asphaltene fraction occurs without the hydrogen saturation observed in hydroconversion or the carbon rejection exhibited by thermal cracking processes. As a result, at least a portion of the asphaltene content is converted by the present processes into a soluble, stable and desulfurized converted liquid product, increasing the yield of higher value liquid products (e.g., hydrocarbon oils derived from asphaltenes. Thus, the converted feedstock produced by the present processes may have an asphaltene content less than that in the hydrocarbon feedstock (or pretreated hydrocarbon feedstock). In any embodiments, the present processes convert at least some asphaltenes to a hydrocarbon oil, such as paraffins. In any embodiments, at least 5%, at least 10%, at least 15%, at least 20% or more of the asphaltene content in the pretreated hydrocarbon feedstock is converted to a liquid hydrocarbon oil in the converted feedstock. Conversion efficiency for the asphaltene content removed from the hydrocarbon or pretreated hydrocarbon feedstocks varies with the amount of sodium used, but is generally high, e.g., at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, up to 98%, up to 99% or even up to 99.9% or 100%, or a range between and including any two of the foregoing values (e.g., 70% to 100%, or 75% to 99.9%, etc.).
The conversion of asphaltenes to smaller, lower molecular weight components with fewer attached functional groups typically results in a reduction in viscosity of at least 40% to as much as 5 orders of magnitude (10000×) and an increase in the API gravity by about 1 to about 3 units for each wt % sulfur removed. In any embodiments, the viscosity of the converted feedstock may be reduced by at least 50 cSt at 50° C. or by at least 40%. In any such embodiments, the viscosity is reduced at 50° C. by at least 100 cSt, at least 200 cSt, at least 300 cSt, or more. For any of the hydrocarbon feedstocks or pretreated hydrocarbon feedstocks disclosed herein with viscosities above 1,000 cSt (see above), the reductions are particularly great and may be at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 99%, or even 100% (e.g., at least a 40 to 99% reduction in viscosity. In any embodiments, the density of the converted feedstock is decreased by about 5 to about 25 kg/m3 per wt % reduction in sulfur content of the converted feedstock compared to the hydrocarbon feedstock or pretreated hydrocarbon feedstock. For example, the decrease in density may be about 5, about 10, about 15, about 20, about 25 kg/m3 or a range between and including any two of the foregoing values (such as about 5 to about 20 kg/m3 or about 10 to about 25 kg/m3, etc.).
As noted above, in any embodiments, the present processes may include pretreating a hydrocarbon feedstock containing impurities prior to contacting with sodium metal. In some cases, a hydrocarbon feedstock may be pretreated to concentrate the impurities in the pretreated hydrocarbon feedstock and therefore reduce the volume of feedstock to process. For example, a virgin crude oil may be distilled to produce one or more light distillate cuts as the purified feedstock and an atmospheric residuum (the pretreated hydrocarbon feedstock) with a higher sulfur content and higher asphaltene content than that in both the purified feedstock and the virgin crude (hydrocarbon feedstock). Alternatively, a hydrocarbon feedstock may be pre-treated to remove a portion of the undesired impurities to provide for a purified feedstock with a lower concentration of impurities and a pretreated hydrocarbon feedstock with impurities that remain after pre-treatment. The pretreated hydrocarbon feedstock may comprise impurities because of the chosen level of conversion or because the pre-treatment process cannot remove the impurity. For example, a vacuum residuum may be treated in a hydroprocessing reactor (such as an LC-Fining® unit or H-Oil® unit) to remove sulfur and convert the residuum fraction to higher value products. However, after hydroprocessing at operating conditions exceeding 350 C and 1500-3000 psig in the presence of catalysts, a recalcitrant sulfur and asphaltene fraction remains in the hydroprocessed bottoms stream. The pre-treatment process may comprise a separation process, a thermal or catalytic conversion process or a treatment process, or combinations of any two or more thereof.
In any embodiments, the pretreatment process may include a separation process that comprises one or more of a physical separation using energy (heat), phase addition (solvent or absorbent), a change in pressure, or application of an external field or gradient to concentrate the impurity in the pretreated hydrocarbon feedstock. The separation process may include gravity separation, flash vaporization, distillation, condensation, drying, liquid-liquid extraction, stripping, absorption, centrifugation, electrostatic separation and their variants. The separation process may further comprise solvent extraction processes, including solvent deasphalting processes, such as Residuum Oil Supercritical Extraction (ROSE®). For example, a hydrocarbon feedstock may be desalted to remove salt and water, an API separator may be used to separate water and solids from oil or a distillation column may be used to separate low sulfur, low boiling point products from high sulfur, high boiling point products in crude oil. The separation process may also require a solid agent or barrier, such as adsorption, filtration, osmosis or their variants. Each of the disclosed separation processes results in a purified feedstock with a lower concentration of impurities than the hydrocarbon feedstock and a pretreated hydrocarbon feedstock with a higher concentration of impurities than the purified feedstock. In any embodiments, the pretreated hydrocarbon feedstock comprises impurities at a higher concentration than in the hydrocarbon feedstock.
In any embodiments, the pretreatment process may include thermal or catalytic processes that modifies the molecular structure or results in rejection of at least a portion of the carbon content of the hydrocarbon feedstock. The thermal conversion process may include a coker, a visbreaker or other process to increase the yield of cracked distillates by rejecting carbon as coke. The catalytic processes may include fixed bed and fluidized bed processes such as, but not limited to catalytic crackers (FCC or Residuum FCC), hydrocrackers, residuum hydrocrackers and hydroconversion (e.g., LC Fining®, H-Oil®). The conversion process may be a hydroprocessing process that requires both hydrogen and catalysts.
The pretreatment step of the present processes may include a treatment process that results in hydrocarbon saturation or removal of a specific impurity on a whole feed basis. Thus, in any embodiments, the pretreating process may include solvent deasphalting, hydrotreating, residuum hydrotreating (RHT), hydrodesulfurization (RDS), hydrodemetallization (HDM) or hydrodenitrification (HDN) or a combination of two or more thereof. While the overall concentration of an impurity (or impurities) may be reduced, treatment processes generally produce a purified feedstock with a lower concentration of impurities than the hydrocarbon feedstock and a pretreated hydrocarbon feedstock with a higher concentration of impurities than the purified feedstock. Nevertheless, the concentration of impurities in the pretreated hydrocarbon feedstock may be lower than the hydrocarbon feedstock. Additionally, catalytic treatment processes cannot typically process feedstocks with high concentrations of impurities in asphaltenes because of accelerated catalyst deactivation from the metals and micro-carbon residue.
Processes of the present technology produces a mixture that includes the converted feedstock and sodium salts. The present processes may further include separating the sodium salts from the converted feedstock. The sodium salts are comprised of particles, which can be quite fine (e.g., <10 μm) and cannot be completely removed by standard separation techniques (e.g., filtration or centrifugation). In any embodiments, the separating may include a heating the mixture of sodium salts and converted feedstock with elemental sulfur to a temperature from about 150° C. to 500° C. to provide a sulfur-treated mixture comprising agglomerated sodium salts; and separating the agglomerated sodium salts from the sulfur treated mixture, to provide a desulfurized liquid hydrocarbon and separated sodium salts. This separation may be carried out as described in U.S. Pat. No. 10,435,631, the entire contents of which are incorporated by reference herein for all purposes.
The present processes may further include recovering metallic sodium from the separated sodium salts. In any embodiments, the present processes may further include electrolyzing the separated sodium salts to provide sodium metal. The separated sodium salts may comprise one or more of sodium sulfide, sodium hydrosulfide, or sodium polysulfide. The electrolyzing may be carried out in an electrochemical cell in accordance with, e.g., U.S. Pat. No. 8,088,270, or U.S. Provisional Patent Application No. 62/985,287, the entire contents of each of which are incorporated by reference herein for all purposes. The electrochemical cell may include an anolyte compartment, a catholyte compartment, and a NaSICON membrane that separates the anolyte compartment from the catholyte compartment. A cathode comprising sodium metal is disposed in a catholyte in the catholyte compartment. An anode comprising the sodium salts are disposed in anolyte in the anolyte compartment. An electrical power supply is electrically connected to the anode and cathode. In any embodiments, the separated sodium salts are dissolved in an organic solvent prior to electrolyzing the salts to provide sodium metal.
Current thermal and catalytic desulfurization processes produce a hydrogen sulfide byproduct that must be treated in a sulfur recovery unit such as a Claus plant. Sulfur recovery units (SRU) are very efficient, but release sulfur emissions during operation; therefore, refining complexes are subject to stringent sulfur emission limits that are regulated by local and national authorities. In many cases, refining complexes operate near or at their sulfur emission limits. Desulfurization using sodium produces an elemental sulfur product that can be stored as a solid or liquid and sold to the market. Each organically bound sulfur removed using sodium displaces an equivalent amount of sulfur as H2S that must be processed in the SRU. As a result, a refining complex gains operational flexibility to either reduce the throughput and operating cost of (and resulting sulfur emissions from) the existing SRU or to increase the sulfur processing capacity of the facility by desulfurizing at least a part of the hydrocarbon feedstock with sodium. In any embodiments, the present processes include a sulfur recovery step employing a sulfur recovery unit (e.g., Claus Plants, SCOT units, or the like). In any such embodiments, the capacity of the sulfur recovery unit is increased proportionately to the sulfur recovered during treatment of the hydrocarbon feedstock with sodium.
Illustrative embodiments of processes of the present technology will now be described with reference to the flow diagrams of
In some embodiments of the present processes utilizing the purification and conversion system 10 of
Alternatively, as shown in
A variety of hydrocarbon feedstocks were treated with sodium metal to demonstrate the wide applicability of sodium metal treatment for removing impurities and improving physical properties. The hydrocarbon feedstocks included virgin crude oils from different geographical locations and geological formations, and a variety of converted and treated feedstocks located within typical refining and upgrading facilities, 700 g of the hydrocarbon feedstock was treated with an appropriate mass of sodium in a 1.8 L Parr continuously stirred tank reactor using a batch or semi-batch system under the following conditions to yield a mixture of converted hydrocarbon and sodium salts. The reaction conditions, feed and product properties are shown in Table 1.
The results from Table 1 clearly indicate that molten sodium metal effectively removes impurities and improves the physical properties of the converted feedstock, therefore improving the fungibility of the converted feedstock. The converted feedstock may now be sold directly as a fuel grade product or converted to higher value products in downstream refinery units rather than be sold as asphalt or high sulfur bunker fuel oil.
A variety of hydrocarbon feedstocks and pretreated hydrocarbon feedstocks were treated with sodium metal in a pilot plant using a continuous system essentially as shown, e.g., in
Similar to Example 1, the results from Table 2 clearly indicate that molten sodium metal effectively removes impurities and improves the physical properties of the converted feedstock, therefore improving the fungibility of the converted feedstock. The converted feedstock may now be sold directly as a fuel grade product or converted to higher value products in downstream refinery units rather than be sold as asphalt or high sulfur bunker fuel oil.
A blended vacuum residuum stream was treated with an increasing molar equivalent of sodium in 5 separate experiments. 700 g of vacuum residuum was contacted with sodium at 350° C. and 750 psig of hydrogen partial pressure. Key results are summarized in Table 3. The effect of treatment with sodium on preferential removal of sulfur from the asphaltene fraction is summarized by:
Refinery intermediate streams (i.e., pretreated hydrocarbon feedstocks) were treated with various molar equivalents of sodium to demonstrate how the choice of molar equivalent of sodium can be used to improve the conversion of hydrocarbons in downstream catalytic conversion processes, 700 g of each refinery intermediate was treated with sodium at 350° C. and 750 psig or 400° C. and 1500 psig of hydrogen partial pressure. Key results are summarized in Table 4
Treatment of hydrocarbon feedstock with a sub-stoichiometric molar equivalent of sodium may be preferable for pre-treating FCC or Residuum Hydrotreater (RHT) feedstocks by preferentially removing the impurities that foul catalysts: asphaltenic sulfur, metals and asphaltenes. A greater proportion of sulfur was removed from the asphaltene fraction in all cases. Additionally, the fraction of metals removed exceeds the fraction of total sulfur removed, indicating that a low sodium/sulfur addition ratio may be favorable to produce a partially converted product with low metals and asphaltenic sulfur content for further processing in downstream refinery processes.
19%
17%
47%
70%
12%
40%
64%
36%
21%
66%
89%
A vacuum residuum feedstock was treated with sodium metal in a pilot plant using a continuous system, e.g., as shown in
The example clearly demonstrates that an on-spec low sulfur fuel oil can be produced when a hydrocarbon feedstock is contacted with an effective amount of sodium and an effective amount of exogenous capping agent.
Four feedstocks from Table 1, vacuum residuum, SDA tar, visbreaker residue and Hydrocracker residue, were treated with sodium metal to demonstrate the improved yield and quality of coker products when pre-treating the coker feedstock with sodium metal prior to thermal conversion, 700 g of the hydrocarbon feedstock was treated with an appropriate mass of sodium in a 1.8 L Parr continuously stirred tank reactor using a batch or semi-batch system under the following conditions to yield a mixture of converted hydrocarbon and sodium salts. The reaction conditions, feed and product properties are shown in Table 1. The product yield and quality of the coker products are estimated using accepted industry correlations (Gary, J. H., and Handwerk, G. E. (2001). “Petroleum Refining.” Marcel Dekker, New York) for both the ‘as received’ hydrocarbon feedstock and the converted feedstock after sodium treatment. The coker products are summarized in Table 6.
The results from Table 6 clearly indicate that when compared to the thermal conversion of the as-received feedstock, treatment the feed with molten sodium metal prior to thermal conversion increases the total liquid yield, reduces the coke yield, increases the proportion of purified product to residual product and reduces the sulfur content of all coker products.
Additionally, the results demonstrate how treating a feedstock with molten sodium metal can unload sulfur recovery processes (i.e., Claus or SCOT plants). In the 4 examples, the sulfur to gas processing (as H2S) is reduced by over 90%. This process configuration is advantageous to increase the sulfur handling capacity for a refining facility without increasing sulfur emissions or exceeding limits.
The coke product qualities for the same four feedstocks from Example 6, vacuum residuum, SDA tar, visbreaker residue and Hydrocracker residue, is estimated using accepted industry correlations (Gary, J. H., and Handwerk, G. E. (2001). “Petroleum Refining.” Marcel Dekker, New York) for both the ‘as received’ hydrocarbon feedstock and the converted feedstock after sodium treatment and are summarized in Table 7. None of the cokes produced from the as-received feed meet anode grade coke specifications, whereas all coke products produced from the converted feedstocks are near or exceed the anode grade coke specifications. The vanadium specification can be achieved by slightly increasing the molar equivalent of sodium in the sodium contacting step.
A comparison was made of distillation properties for hydrocarbon feedstocks before and after treatment with sodium in accordance with the procedure of Example 1. The results in Table 8 show improved properties, with a reduction in the residue fraction of 1-10% and associated increases in the higher-value distillate and gasoil fractions of 0.5-3% and 0.5-8% respectively. This improved product profile provides higher value products from a given volume of feed, e.g., when conducting distillations after desulfurization using sodium.
While certain embodiments have been illustrated and described, a person with ordinary skill in the art, after reading the foregoing specification, can affect changes, substitutions of equivalents and other types of alterations to the processes of the present technology and products thereof as set forth herein. Each aspect and embodiment described above can also have included or incorporated therewith such variations or aspects as disclosed in regard to any or all of the other aspects and embodiments.
The present technology is also not to be limited in terms of the particular aspects described herein, which are intended as single illustrations of individual aspects of the present technology. Many modifications and variations of this present technology can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods within the scope of the present technology, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. It is to be understood that this present technology is not limited to particular methods, feedstocks, compositions, or conditions, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. Thus, it is intended that the specification be considered as exemplary only with the breadth, scope and spirit of the present technology indicated only by the appended claims, definitions therein and any equivalents thereof.
The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms “comprising,” “including,” “containing,” etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Likewise, the use of the terms “comprising,” “including,” “containing,” etc. shall be understood to disclose embodiments using the terms “consisting essentially of” and “consisting of.” The phrase “consisting essentially of” will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase “consisting of” excludes any element not specified.
In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group. Each of the narrower species and subgeneric groupings falling within the generic disclosure also form part of the invention. This includes the generic description of the invention with a proviso or negative limitation removing any subject matter from the genus, regardless of whether or not the excised material is specifically recited herein.
As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.
All publications, patent applications, issued patents, and other documents (for example, journals, articles and/or textbooks) referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.
Other embodiments are set forth in the following claims, along with the full scope of equivalents to which such claims are entitled.
The present application claims priority to U.S. Provisional Application No. 63/027,052 filed on May 19, 2020, the contents of which are incorporated herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/033244 | 5/19/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63027052 | May 2020 | US |
