Process for producing low carbon intensity colorless hydrocarbon products

Abstract

The present disclosure relates to a process wherein a hydrocarbonaceous feedstock and a gas comprising hydrogen are contacted under active hydrotreating conditions with a hydrotreating catalyst (e.g. an isomerization catalyst or a hydrocracking catalyst) to provide a hydrotreated process stream, wherein the hydrotreated process stream is contacted with a catalyst comprising a silicoaluminate, characterized in that, prior to contacting the hydrotreating catalyst, the entire hydrotreated process stream is directed to cool by at least 20 °C.

Description

Technical Field

[0001] This application relates to the field of converting feedstocks containing n-alkanes and cyclic compounds (e.g., aromatics and cycloalkanes) into hydrocarbons with little or no color by hydrogenation. Background Technology

[0002] Converting bio-derived oils and fats into transport fuels with good low-temperature performance involves the requirement to convert linear n-alkanes into branched isoalkanes via isomerization or hydrocracking, which requires elevated temperatures, especially if a sulfurized isomerization catalyst is used.

[0003] When feedstocks are treated at elevated temperatures in the presence of a catalyst with hydrogenation capabilities (including isomerization and hydrocracking catalysts), a certain amount of colored compounds (presumably polycyclic aromatic hydrocarbons) may be formed. This may be due to either an equilibrium between cycloalkanes and polycyclic aromatic hydrocarbons that shifts towards aromatic hydrocarbon formation during the elevated temperature isomerization step in the hydrogenation process of feedstocks containing n-alkanes and cycloalkanes and / or aromatic hydrocarbons, or due to the formation of polycyclic aromatic hydrocarbons through other side reactions.

[0004] If the feedstock contains sulfur (as is the case with fossil feedstocks and some biological feedstocks, including pyrolysis oil and crude tall oil from sewage sludge), it may be preferable to carry out isomerization on a sulfurized isomerization catalyst at elevated temperatures, resulting in the formation of colored compounds. Summary of the Invention

[0005] We have now identified a method for hydrotreating feedstocks containing n-alkanes, cycloalkanes, and / or aromatics to produce a colorless product with good low-temperature performance while employing a cost-effective base metal catalyst. This method involves a final process step in which the product is contacted at a reduced temperature with a catalytically active material containing a hydrogenated metal to allow for a low-temperature equilibrium that favors non-aromatic compounds over aromatic compounds.

[0006] definition

[0007] For the purposes of this application, wt% should refer to weight / weight, and vol% should refer to volume / volume.

[0008] For the purposes of this application, the unit is ppm. wt Should refer to weight / parts per million, unit ppm vol It should refer to volume / parts per million.

[0009] Where gas phase concentrations are given, they are given in molar concentrations unless otherwise specified.

[0010] Saybolt colors are determined according to ASTM D 156 and ASTM D6045 and reported as numbers ranging from -16 (light yellow) to 30 (colorless).

[0011] The term "material exhibiting catalytic activity in a chemical reaction under active conditions" (where the chemical reaction can be hydrotreatment, hydrogenation, isomerization, or hydrocracking) should be understood as a combination of materials and conditions under which significant catalytic activity and preference for said chemical reaction occur. As those skilled in the art will recognize, most reactions will exhibit some amount of side reactions, but unless otherwise stated, the term "material exhibiting catalytic activity in a chemical reaction" should be understood as a combination of materials and conditions under which commercially relevant amounts of conversion occur with higher selectivity than any other chemical reaction. The term "having chemical reaction function" should be interpreted as having activity, but not necessarily as being the dominant reaction.

[0012] Technical issues

[0013] Co-processing fossil fuels with bio-based materials to produce transportation fuels is beneficial. Both types of feedstocks require heteroatom removal; primarily oxygen (5-40 wt%) from bio-based feedstocks, and sulfur and nitrogen (both 100 ppm) from fossil feedstocks. wt -2 wt%). The removal of heteroatoms is accomplished through hydrotreating in the presence of a catalytically active material containing a hydrogenating metal and a refractory support. The hydrogenating metal can typically be one or more sulfided metals; molybdenum, tungsten, nickel, and cobalt (also known as base metals, sulfided catalysts, or acidic mode catalysts). Acidic mode catalysts are generally preferred in hydrotreating because they are highly robust to impurities (including sulfur), thus avoiding the separation steps required for noble metal catalysts. However, acidic mode catalysts have lower activity, thus requiring higher temperatures.

[0014] Fossil fuels have a lower heteroatom content, resulting in lower heat release during exothermic hydrogenation. Furthermore, fossil fuel availability may be higher. Combining these two hydrocarbon sources can lead to higher biomaterial utilization rates.

[0015] If the feedstock contains a certain amount of alkanes, low-temperature performance may be insufficient, necessitating isomerization or hydrocracking. Isomerization and hydrocracking reactions are catalyzed by bifunctional catalysts with acidic sites and hydrogenation capabilities. The simplified mechanism involves the formation of chemisorbed carbocations at the acidic sites, followed by hydrogenation of the carbocations and skeletal rearrangement. Therefore, this can be carried out in the presence of hydrogen and materials containing one or more hydrogenated metals (e.g., sulfided molybdenum, tungsten, nickel, and cobalt, or elemental platinum and palladium or other platinum group metals (also known as noble metals, unsulfided catalysts, or sweet mode catalysts)) and acidic materials (e.g., aluminosilicates may be desirable). Aluminosilicates can be one or more silica-alumina, zeolites, and molecular sieves, including aluminosilicate phosphates. If the aluminosilicate is a molecular sieve exhibiting high shape selectivity and having topologies such as MOR, FER, MRE, MWW, AEL, TON, and MTT, then isomerization will be the dominant reaction; while if the aluminosilicate is a silica-alumina molecular sieve or has topologies such as MFI, BEA, and FAU, then hydrocracking will be the dominant reaction.

[0016] Acidic catalysts are sometimes not preferred, for example, in isomerization, because their selectivity may be lower than that of unsulfurized catalysts, potentially leading to yield losses. However, if the feedstock contains sulfur, using acidic catalysts offers significant benefits in avoiding intermediate gas / liquid separation between hydrotreatment and isomerization. Nevertheless, isomerization in acidic mode also requires higher temperatures because the activity of acidic catalysts is lower than that of unsulfurized catalysts.

[0017] Coloration of the product has been observed when feedstocks are treated at elevated temperatures in the presence of a catalyst with hydrogenation capabilities. Without being bound by theory, this is believed to be due to the formation of a certain amount of polycyclic aromatic hydrocarbons (PAHs), either due to a shift in the equilibrium between cycloalkanes and PAHs (which shifts towards aromatics with increasing temperature and decreasing pressure), or due to the formation of cyclic structures and aromatics during hydrogenation, for example, via Diels-Alder condensation side reactions during the hydrogenation of feedstocks containing n-alkanes and cycloalkanes and / or aromatics.

[0018] Quantitative analysis of low concentrations of polycyclic aromatic hydrocarbons (PAHs) in hydrocarbon products is not a standard method. However, since many PAHs are colored compounds, product color is a sensitive indicator, and therefore the Seypot method can be used to indicate even sub-ppm levels of PAHs, although other compounds can also color hydrocarbons. Low Seypot color values ​​indicate colored hydrocarbons, while a maximum Seypot value of 30 indicates colorless hydrocarbons.

[0019] It is well known that catalysts gradually lose activity. To delay the time when the catalyst must be replaced (“End of Run” – EOR – time), the conditions are typically made more stringent as the EOR approaches. This usually involves raising the isomerization temperature above 340°C, and correspondingly increases the risk of shifting the equilibrium conditions to favor aromatics rather than saturated hydrocarbons.

[0020] Solution to the problem

[0021] As previously mentioned, the formation of polycyclic aromatic hydrocarbons (PAHs) is undesirable, and aromatics are highly stable compounds requiring significant saturation. Furthermore, the cost of using noble metal catalysts and the necessary separation of hydrogen-rich gases containing sulfides and ammonia are also undesirable. However, we have determined that by operating the hydrogenation reactor at a temperature lower than that of the upstream isomerization reactor (e.g., 20°C, 40°C, 60°C, 80°C, or more lower than that of the upstream isomerization reactor using a base metal catalyst), the equilibrium between PAHs and cycloalkanes shifts towards cycloalkanes, resulting in a final product containing low levels of PAHs and thus exhibiting a high Seypot color value. The temperature of the hydrogenation reactor can be controlled by a cooling system, typically through heat exchange with the process stream or heat exchange medium (such as steam), but quenching by mixing with a cold stream is also a possibility.

[0022] US 2005 / 0133411 discloses the formation of polycyclic aromatic hydrocarbons (PAHs) at elevated temperatures during hydrodesulfurization of fossil feedstocks, and the removal of these PAHs related to cryogenic hydrotreating, but the document does not identify similar issues related to isomerization catalysts.

[0023] Beneficial effects of the invention

[0024] In a first aspect, this disclosure relates to a method for producing a hydrocarbon product comprising a boiling fraction in the range of aviation fuel from a hydrocarbon composition, wherein at least 80 wt% of the hydrocarbon composition boils in the range of 150°C to 400°C, the method comprising the steps of: (a) a hydrotreating step, wherein the hydrocarbon composition and a hydrogen-containing gas are contacted with a catalytically active material comprising aluminosilicates and one or more sulfide metals (selected from molybdenum, tungsten, nickel, and cobalt) at an inlet temperature above 340°C, 350°C, or 360°C; (b) a cooling step, wherein the hydrotreated process stream is cooled to a temperature above 20°C (e.g., 40°C or 60°C) in the presence of a hydrotreating catalyst at an inlet temperature above 200°C and below 340°C; and (d) optionally, removing one or more products after fractionation, wherein at least 80% by weight of the hydrocarbon composition boils in the range of aviation fuel.

[0025] This provides the following related benefits: a method is provided that enables the economical production of aviation fuel with a Seybert color value of at least 20, 25, or 30 from hydrocarbon compositions comprising colored compound precursors and having cloud points above -20°C, -10°C, or 0°C, thus requiring hydrotreating in the form of isomerization or hydrocracking, which necessitates cooling of the hydrotreated process stream at temperatures above 340°C and below 400°C or 420°C. A more specific aspect of this disclosure may relate to hydrocarbon compositions comprising 1 wt% to 5 wt% or 10 wt% of diaromatics.

[0026] In a second aspect, this disclosure relates to generating hydrocarbon products by means of the method according to the first aspect, wherein the hydrogenation catalyst is a sulfide hydrogenation catalyst comprising a refractory support (e.g., alumina, silica, titanium dioxide, and silica-alumina) and an active hydrogenation metal (one or more of nickel, cobalt, tungsten, and molybdenum in sulfide form) at a total concentration of 5 to 30 wt%.

[0027] This offers the following related benefits: such materials are active at low temperatures (e.g., 230°C to 270°C, 300°C, or 320°C), allowing the equilibrium to shift towards aromatic saturation without requiring a prior separation step to remove sulfur. The sulfide hydrogenation catalyst may contain at least 1 wt%, at least 5 wt%, or at least 15 wt% to up to 20 wt%, up to 30 wt%, or up to 50 wt% of molybdenum or tungsten, promoted by cobalt or nickel in a ratio ranging from 0.1:1 (Co+Ni):(Mo+W) to 2:1 (Co+Ni):(Mo+W) (where the ratio refers to the molar ratio of the total amount of Co and Ni to the total amount of Mo and W).

[0028] In a third aspect, this disclosure relates to the method according to the first aspect, wherein the hydrogenation catalyst is an unsulfurized hydrogenation catalyst comprising a refractory support (e.g., alumina, silica, titanium dioxide, and silica-alumina) and an active hydrogenation metal (any one or more of platinum, palladium, or nickel in elemental form), with a total concentration of 0.1 to 5 wt%.

[0029] This has the following associated benefits: such materials are active at extremely low temperatures (e.g., 200°C to 250°C, 270°C, or 300°C), which can shift the equilibrium toward aromatic saturation, but if sulfur is present, a prior separation step to remove sulfur and the addition of a pure stream containing hydrogen may be required.

[0030] In a fourth aspect, this disclosure relates to a method according to any of the preceding aspects, wherein the hydrocarbon composition comprises at least 1%wt, 5%wt, or 10%wt of aromatics and cycloalkanes in aggregate.

[0031] This has the following related benefits: such hydrocarbon compositions have a high probability of forming colored products during high-temperature isomerization, regardless of whether the aromatics originate from fossil fuels, from the thermal decomposition products of renewable materials, or are formed through side reactions during hydrodeoxygenation.

[0032] In a fifth aspect, this disclosure relates to a method according to any of the preceding aspects, wherein the hydrocarbon composition is provided by contacting and reacting a hydrocarbon feedstock and a hydrogen-containing gas with a hydrotreating catalyst under active hydrotreating conditions.

[0033] This has the following related benefits: it provides a method in which hydrocarbon compositions undergo cost-effective combined hydrogenation and isomerization while ensuring products with acceptable colors.

[0034] In a sixth aspect, this disclosure relates to the method according to the fifth aspect above, wherein the hydrocarbon feedstock contains at least 10 ppm. wt S, 50 ppm wt S or 500 ppm wt S.

[0035] This offers the following benefits: it provides a method for processing feedstocks requiring sulfur removal and cloud point reduction, such as hydrocarbon feedstocks containing a combination of fossil and biological materials. Typically, the sulfur content will be less than 10,000 ppm. wt S.

[0036] In a seventh aspect, this disclosure relates to the method according to the fifth or sixth aspect above, wherein the hydrocarbon feedstock contains at least 5 ppm wt N, 10 ppm wt N or 50 ppm wt N.

[0037] This offers the following benefits: it provides a method for processing feedstocks requiring nitrogen removal and cloud point reduction, such as hydrocarbon feedstocks containing a combination of fossil and biological materials. Typically, the nitrogen content will be less than 10,000 ppm. wt N.

[0038] In an eighth aspect, this disclosure relates to the method according to the fifth, sixth or seventh aspects above, wherein the hydrocarbon feedstock contains a certain amount (e.g., at least 10 wt%, 20 wt% or 50 wt% and less than 99 wt% or 95 wt%) of fossil feedstock.

[0039] This has the following related benefits: fossil raw materials are highly available, while the process of processing biological materials has no substantial impact on the performance of the product.

[0040] In a ninth aspect, this disclosure relates to methods according to the fifth, sixth, seventh or eighth aspects above, wherein the hydrocarbon feedstock contains an amount (e.g., at least 1 wt%, 5 wt% or 10 wt% and less than 50 wt% or 90 wt%) of bio-derived feedstock, such as animal fats, vegetable oils, tall oils and thermal decomposition products of solid materials (including municipal or biological waste).

[0041] This has the following related benefits: it provides a method for producing raw materials with a reduced carbon footprint.

[0042] In a tenth aspect, this disclosure relates to a method in which a hydrocarbon feedstock and a hydrogen-containing gas are contacted with a hydrotreating catalyst (e.g., an isomerization catalyst or a hydrocracking catalyst) under active hydrotreating conditions to provide a hydrotreating process stream, wherein the hydrotreating process stream is contacted with a catalyst containing aluminosilicates, characterized in that the entire hydrotreating process stream is guided to be cooled by at least 20°C, such as 40°C or 60°C, prior to contact with the hydrotreating catalyst.

[0043] This has the following related benefits: it provides a simple process without intermediate separations, and the process has a low net yield of polycyclic aromatic hydrocarbons.

[0044] A further aspect of this disclosure relates to a process apparatus comprising: a hydrotreating reactor having an inlet and an outlet and containing a hydrotreating catalyst comprising aluminosilicates and metal sulfides; a cooling device having an inlet and an outlet; and a hydrotreating reactor having an inlet and an outlet and containing a hydrotreating catalyst, wherein the outlet of the hydrotreating reactor is in fluid communication with the inlet of the cooling device, and the outlet of the cooling device is in fluid communication with the inlet of the hydrotreating reactor.

[0045] This has the following related benefits: it provides a hydrotreating process that modulates the low-temperature flow properties of hydrocarbon mixtures while avoiding product discoloration. Attached Figure Description

[0046] Figure 1 The method according to the present invention is shown.

[0047] Figure 1

[0048] [ Figure 1The process layout according to this disclosure is described. A mixture of hydrocarbons comprising triglycerides or linear fatty acids, aromatics (such as xylene), phenols or resin acids, and organosulfur compounds (such as thiophene) is directed to the process as feedstock (2). The feedstock can be a single stream or a combination of one or more of bio-derived oils (such as vegetable oils, animal fats, or crude tallow), pyrolysis oils, and petrochemicals (such as kerosene or VGO (vacuum gas oil)). Feedstock (2) is combined with an optional liquid recirculation stream (26) and a certain amount of hydrogen-rich gas (4), which may be partially provided by the recirculated gas. Feedstock (2) and hydrogen-rich gas (4) together form a reactor feed stream (6), which is directed to a hydrotreating reactor (HDT) containing a catalyst with hydrotreating activity, wherein organically combined oxygen and sulfur react under hydrotreating conditions to provide water, hydrogen sulfide, and possibly carbon oxides as products, and release an intermediate hydrocarbon-rich stream (8) in which the heteroatom content in the hydrocarbons is minimized. The hydrotreating reactor can have multiple beds with intermediate quenching hydrogen injection to control temperature, and the feedstock can also be diverted and partially directed to individual reactor beds, but this part is not shown in the figure. The intermediate hydrocarbon-rich stream (8) is transferred to a conversion reactor containing catalytically active material in isomerization (ISOM) to form an isomerization process stream (10) containing branched hydrocarbons. In the figure, the conversion reactor also contains catalytically active material in hydrocracking (HDC) to obtain a variation in boiling point range, but in practice, only a single type of catalytically active material may be present in this reactor. Due to the isomerization activity requirements, the temperature of the catalytically active material in isomerization (ISOM) is elevated, so the isomerization process stream (10) may also contain a certain amount of polycyclic aromatic hydrocarbons as previously described. In a cooler (COOL), the isomerization process stream (10) is cooled, and the cooled isomerization process stream (12) is directed to contact the catalytically active material in hydrotreating (HYD) to form a partially saturated process stream (14). In this configuration, the partially saturated process stream (14) contains hydrocarbons boiling over a wide range of conditions and is directed to the fractionation section (FRAC), which is shown as a single unit but typically comprises multiple components. In this illustration, overhead vapor (16), naphtha (18), aviation fuel (20), and heavy understream (22) are produced, and the heavy understream (22) is split into heavy product (24) and liquid recirculation stream (26).

[0049] An implementation scheme could be considered as a variant of this process layout, such as an implementation scheme with a single catalytic activity, rather than an implementation scheme with two materials that are active in both isomerization and hydrocracking reactions, if the boiling point range of the products is satisfactory.

[0050] Example

[0051] A feedstock containing 3 wt% animal fat and 97 wt% kerosene was hydrotreated on a hydrotreating catalyst containing 11 wt% Mo sulfide supported on alumina, and then hydroisomerized in an isothermal reactor at 340°C on an isomerization catalyst containing 3 wt% Ni sulfide and 23 wt% W supported on a support comprising zeolite and alumina. Two substitution tests were performed; one without further treatment, and the second with the product directed to a hydrotreating reactor containing a hydrotreating catalyst containing 3 wt% Ni and 16 wt% Mo supported on alumina at 240–280°C.

[0052] In experiments using a color reactor, the product had a low Seybert color value of 17, while the hydrogenation reactor improved the product's Seybert color to >30, corresponding to a colorless liquid.

[0053] Patent documents

[0054] PTL1: US 2005 / 0133411

[0055] Table 1

Claims

1. A method for producing a hydrocarbon product from a hydrocarbon composition, said hydrocarbon product comprising a fraction boiling in the range of aviation fuel, said hydrocarbon composition having at least 80 wt% boiling in the range of 150°C to 400°C, said method comprising the following steps: a. A hydrotreating step, wherein a hydrocarbon composition and a hydrogen-containing gas are contacted with a catalytically active material at an inlet temperature of 340°C, 350°C, or above 360°C, said catalytically active material comprising an aluminosilicate and one or more sulfided metals selected from molybdenum, tungsten, nickel, and cobalt. b. Cooling step, cooling the hydrogenated process stream by at least 20°C, for example 40°C or 60°C, to a temperature above 200°C. c. Saturation step: At an inlet temperature above 200°C and below 340°C, in the presence of a hydrogenation catalyst, the hydrogenated process stream is guided to the saturation step. d. After optional fractionation, one or more products are removed, wherein at least 80 wt% of the hydrocarbon composition boils in the aviation fuel range.

2. The method according to claim 1, wherein the hydrogenation catalyst is a sulfide hydrogenation catalyst comprising a refractory support, such as alumina, silica, titanium dioxide, and silica-alumina, and an active hydrogenation metal, which is one or more sulfide forms of nickel, cobalt, tungsten, and molybdenum, with a total concentration of 5 to 30 wt%.

3. The method according to claim 1, wherein the hydrogenation catalyst is an unsulfurized hydrogenation catalyst comprising a refractory support, such as alumina, silica, titanium dioxide, and silica-alumina, and an active hydrogenation metal, which is one or more elemental forms of platinum, palladium, or nickel, with a total concentration of 0.1 to 5 wt%.

4. The method according to claim 1, 2 or 3, wherein the hydrocarbon composition comprises at least 1%wt, 5%wt or 10%wt of aromatics and cycloalkanes in total.

5. The method according to claim 1, 2, 3 or 4, wherein the hydrocarbon composition is provided by reacting a hydrocarbon feedstock and a hydrogen-containing gas with a hydrotreating catalyst under active hydrotreating conditions.

6. The method according to claim 5, wherein the hydrocarbon feedstock contains at least 10 ppm wt S, 50 ppm wt S or 500 ppm wt S.

7. The method according to claim 5 or 6, wherein the hydrocarbon feedstock contains at least 5 ppm. wt N, 10 ppm wt N or 50 ppm wt N.

8. The method according to claim 5, 6 or 7, wherein the hydrocarbon feedstock contains a certain amount, for example at least 10 wt%, 20 wt% or 50 wt% and less than 99 wt% or 95 wt%, of fossil feedstock.

9. The method according to claim 5, 6, 7 or 8, wherein the hydrocarbon feedstock contains a certain amount, for example at least 1 wt%, 5 wt% or 10 wt% and less than 50 wt% or 90 wt%, of a bio-derived feedstock, such as animal fat, vegetable oil, tall oil and thermal decomposition products of solid materials.

10. A method in which a hydrocarbon feedstock and a hydrogen-containing gas are contacted with a hydrotreating catalyst, such as an isomerization catalyst or a hydrocracking catalyst, under active hydrotreating conditions to provide a hydrotreating process stream, wherein the hydrotreating process stream is contacted with a catalyst comprising an aluminosilicate, characterized in that, Before contact with the hydrogenation catalyst, the entire post-hydrogenation process stream is directed to be cooled to at least 20°C, such as 40°C or 60°C.

11. A process apparatus for performing the method according to any of the preceding claims, the process apparatus comprising: A hydrotreating reactor having an inlet and an outlet and containing a hydrotreating catalyst comprising aluminosilicates and metal sulfides; A cooling device having an inlet and an outlet; And a hydrogenation reactor having an inlet and an outlet and containing a hydrogenation catalyst, wherein the outlet of the hydrogenation reactor is in fluid communication with the inlet of a cooling device, and the outlet of the cooling device is in fluid communication with the inlet of the hydrogenation reactor.

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