Method for producing renewable fuels

Abstract

A process for producing hydrocarbons from an oxygenate feedstock having high nitrogen impurities, such as animal fats, is described. The process includes hydroprocessing the oxygenate feedstock in a first hydroprocessing reactor and further hydroprocessing in a second hydroprocessing reactor, with removal of the gas phase between the two reactors. The particular process arrangement is effective in removing nitrogen impurities from the resulting hydrocarbon product, resulting in an increased cloud point after isomerization.

Description

Technical Field

[0001] This invention relates to a method for preparing hydrocarbons from oxygenated hydrocarbon feedstocks with nitrogen impurities of 500 wppm or higher (based on elemental nitrogen), and particularly to improving the quality and quantity of aviation fuel obtained therefrom. Background Technology

[0002] Converting petroleum products (such as crude oil) and renewable oils (such as vegetable oils or animal fats) into valuable products, such as transportation fuels (such as gasoline, jet fuel, and diesel), requires a hydrotreating process that consumes hydrogen.

[0003] The refining of heavy crude oil and low-quality vegetable oils and animal fats (such as waste animal fats) increases the demand for hydrogen in hydrotreating processes. Therefore, the production, recycling, and purchase of hydrogen for petroleum hydrotreating have a significant impact on refinery operating costs.

[0004] Compared to theoretical consumption, hydrotreating of petroleum and renewable oils uses excess hydrogen. The hydrogen remaining after the hydrotreating step can be purified and recycled along with additional fresh hydrogen to compensate for the hydrogen consumed in the hydrotreating step—this is known as supplemental hydrogen.

[0005] During hydrotreating, various reactions occur to varying degrees depending on the feedstock composition. Hydrotreating reactions include double bond hydrogenation, hydrodeoxygenation (HDO), hydrodesulfurization (HDS), nitrogen removal (HDN), hydrodearomatization (HDAr), hydrocracking (HC), and hydroisomerization.

[0006] Hydroisomerization is typically carried out on bifunctional catalysts with both metal dehydrogenation and acidification functions, such as platinum or palladium catalysts and molecular sieves like SAPO-11. The isomerization selectivity of the catalyst is important; that is, if a decrease in the average molecular weight of the feed is undesirable during the hydroisomerization process, hydrocracking, which also occurs to some extent during hydroisomerization, is usually suppressed. This involves a balance between the metal dehydrogenation function and the acidification function, which is sensitive to elements capable of altering this balance. It is speculated that amines neutralize strong acid sites, resulting in lower catalyst acidity and activity. Sulfur is known to poison the metal dehydrogenation function of noble metal catalysts.

[0007] One of the common feedstock impurities is nitrogen, a well-known component of petroleum and renewable source oils. It has been reported to be present at an average level of 940 wppm in crude oil, with levels as high as 7500 wppm (Manrique et al., (1997)). Basic Nitrogen Compounds in Crude Oils: Effect on Mineral Dissolution During Acid Stimulation Processes(SPE-37224-MS; https: / / www.onepetro.org / conference-paper / SPE-37224-MS). It is not uncommon for animal fats to contain 1000 ppm or even higher levels of nitrogen. A typical method for treating undesirable impurities such as nitrogen impurities in feedstocks is to purify the feedstock prior to hydrogenation. Removing water-soluble nitrogen compounds via degumming is straightforward. However, in animal fats, most nitrogen compounds are oil-soluble and more difficult to remove than water-soluble nitrogen compounds.

[0008] US 2011 / 0094149 A1 (granted to IFP Energies Nouvelles) describes a method for hydrotreating a feed from a renewable source in two catalytic zones using a molybdenum catalyst, wherein, due to the exothermic nature of the hydrotreating reaction, the gaseous and liquid effluents from the bed are at higher temperatures than the inlet and are directly used as recirculation to heat the fresh feed entering the catalytic zones. US 2011 / 0094149 A1 exemplifies the invention by using high-quality palm oil and soybean oil with trace amounts of nitrogen impurities of 15 and 23 ppm, respectively, and mentions that feed from renewable sources typically contains various impurities, such as nitrogen impurities typically ranging from 1-100 ppm and even up to 1 wt%.

[0009] US 2011 / 0094149 A1 reduces the nitrogen content in the examples to about 2% of the original amount and does not hydrogenate any impure feedstock with nitrogen content outside the general range of 1-100 ppm.

[0010] Under the conditions described in US 2011 / 0094149 A1, Comparative Example 1 involved hydrogenation and isomerization of animal fat with a nitrogen content of about 1 wt%, demonstrating that impure feedstocks with nitrogen contents outside the general range of 1-100 ppm can be hydrogenated. However, the nitrogen content after the hydrodeoxygenation stage was about 2-5 ppm, and after isomerization, the yield of the aviation fuel fraction was only 5% compared to the requirements for aviation fuel, with a pour point as high as -10°C.

[0011] Therefore, a further hydrotreating process is needed that can effectively hydrotreat oxygenated hydrocarbons with nitrogen impurities outside the general range of 1-100 ppm while ensuring low nitrogen content in the hydrotreating products. Furthermore, a process is needed to produce high-quality aviation fuel fractions with good low-temperature flow properties from oxygenated hydrocarbons with nitrogen impurities outside the general range of 1-100 ppm.

[0012] It is possible to further purify the feed before hydrogenation to remove as much nitrogen as possible. However, while purification methods for removing water-soluble nitrogen are easy to implement, the large amount of nitrogen in animal fats is oil-soluble and more difficult to remove. Summary of the Invention

[0013] The present invention is made in view of the above-mentioned prior art, and the object of the present invention is to provide a method for improving the quality of hydrotreated products obtained from oxygenated hydrocarbon feedstock containing nitrogen impurities in a general range of 1-100 ppm, particularly wherein the improved quality includes at least a small amount of nitrogen impurities in the product.

[0014] To address this problem, the present invention provides a method for preparing hydrocarbons from an oxygenated hydrocarbon feedstock (e.g., animal fat) having nitrogen impurities of 150 wppm or higher, such as 300 ppm or 500 wppm or higher (based on elemental nitrogen). The method comprises a first hydrotreating reactor (101) and a second hydrotreating reactor (102), wherein the effluent from the first hydrotreating reactor is purified, and wherein the purified effluent from the first hydrotreating reactor (101) is hydrotreated in the second hydrotreating reactor (102) at a higher temperature, and wherein the feed to the second hydrotreating reactor is not mixed with the oxygenated feedstock.

[0015] Specifically, the present invention relates to a method for preparing hydrocarbons from oxygen-containing hydrocarbon feedstocks, the oxygen-containing hydrocarbon feedstocks having nitrogen impurities (calculated as elemental nitrogen) of 300 wppm to 3000 wppm or higher, the method comprising: - A first hydrotreating reactor (101) includes at least one catalytic zone (105), wherein a hydrotreating inlet stream comprising an oxygenated hydrocarbon feedstock (104) and optionally a hydrocarbon diluent (126) is introduced into the catalytic zone along with a hydrogen-rich gas (120) at an inlet temperature and pressure that at least causes hydrodeoxygenation and hydrodenitrification, so that the effluent (106) from the first hydrotreating reactor is primarily composed of hydrocarbons, and wherein the oxygenated hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons; - The effluent (106) from the first hydrotreating reactor undergoes a first separation stage (107), wherein at least a portion of the effluent (106) is separated into a first gaseous fraction (121) and a first hydrotreating liquid (108), wherein the first hydrotreating liquid contains greater than or equal to 95 wt% hydrocarbons and greater than 1 wppm nitrogen; - At an inlet temperature (higher than the inlet temperature in the first hydrotreating reactor) and pressure that cause hydrodeoxygenation and hydrodenitrogenation, at least a portion of the first hydrotreating liquid (108) and hydrogen-rich gas (120) are introduced into a second hydrotreating reactor (102), the second hydrotreating reactor including at least one catalytic zone, wherein the first hydrotreating liquid is not mixed with a feed having an oxygen content higher than that of the first hydrotreating liquid, and wherein the first hydrotreating liquid is not mixed with a feed having a nitrogen content higher than that of the first hydrotreating liquid; - The effluent (130) from the second hydrotreating reactor (102) undergoes one or more second separation stages (111) and / or stripping stages (114), wherein the effluent (130) is separated into a second gaseous fraction (113) and a second hydrotreating liquid (112) and / or a stripped hydrotreating liquid (115), wherein the second hydrotreating liquid (112) or the stripped hydrotreating liquid (115) contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 wppm nitrogen, preferably less than or equal to 0.4 wppm nitrogen, for example less than or equal to 0.3 wppm nitrogen (as determined by ASTM D4629), on an elemental nitrogen basis; In other words, the inventors of this invention discovered in a first aspect of the invention that oxygenated hydrocarbons with nitrogen impurities far exceeding those typically present can be effectively hydrogenated in only two hydrogenation reactors, each containing at least one catalytic zone, when ammonia and other low-boiling-point amines are removed from the effluent of a first hydrogenation reactor by separating it into gaseous and liquid phases, and then hydrogenated from the resulting liquid phase in a second hydrogenation reactor, wherein this liquid phase is neither combined with other oxygenated hydrocarbon feeds nor with other feeds having a nitrogen content higher than that of the liquid from the first hydrogenation reactor. The effluent from the second hydrogenation reactor is then separated into a gaseous and a liquid stream from the second hydrogenation reactor; this separation may be a stripping step or a subsequent stripping step, wherein the liquid stream from the second hydrogenation reactor may be stripped with a stripping gas such as hydrogen to reduce the nitrogen content of the stripped liquid to 0.3 wppm or lower.

[0016] The second hydrotreated liquid (112) can be used as its own product or as a process recycle. The second hydrotreated liquid can also be isomerized in a first isomerization reactor (103) including at least one catalytic zone, wherein the second hydrotreated liquid and a hydrogen-rich gas (120) having less than or equal to 1 ppm (mol / mol) of nitrogen (as elemental nitrogen) are introduced into the catalytic zone at an inlet temperature and pressure that at least causes hydroisomerization to produce a first isomerized effluent (116); wherein the first isomerized effluent (116) from the first isomerization reactor (103) undergoes a third separation stage (117), wherein the first isomerized effluent (116) is separated into a third gaseous fraction (118) and a first isomerized liquid (119), wherein the first isomerized liquid contains greater than or equal to 30 wt% branched hydrocarbons and / or the branched hydrocarbons are increased by greater than or equal to 30 wt% compared with the second hydrotreated liquid.

[0017] For example, the second hydrotreated liquid (112) or the second hydrotreated effluent (130) is subjected to a stripping stage (114), wherein the second hydrotreated liquid or the second hydrotreated effluent is stripped with a hydrogen-rich gas (120), such that the stripped hydrotreated liquid (115) has less than or equal to 0.4 wppm of nitrogen (as elemental nitrogen), and a lower nitrogen content compared to the second hydrotreated liquid (112), for example, less than or equal to 0.4 wppm of nitrogen (as elemental nitrogen); the stripped hydrotreated liquid (115) may be subjected to an isomerization step in a first isomerization reactor (103) comprising at least one catalytic zone, wherein the stripped hydrotreated liquid (115) and the first isomerized effluent (116) are at a temperature and pressure that at least causes hydroisomerization to produce a first isomerized effluent (116), the stripped hydrotreated liquid (115) and the first isomerized effluent (130) have less than or equal to 0.4 wppm of nitrogen (as elemental nitrogen). A hydrogen-rich gas (120) of ppm (mol / mol) nitrogen (as elemental nitrogen) is introduced into the catalytic zone; wherein the first isomerization effluent (116) from the first isomerization reactor (103) undergoes a third separation stage (117), wherein the first isomerization effluent (116) is separated into a third gaseous fraction (118) and a first isomerization liquid (119), wherein the first isomerization liquid contains greater than or equal to 30 wt% branched hydrocarbons.

[0018] The first isomerized liquid (119) can be separated into at least one aviation fuel with a cloud point of -40°C or lower, such as -47°C or lower.

[0019] Cooling can be applied during the separation phase of the effluent (106) of the first hydrotreating process to the extent that the temperature of the liquid (108) of the first hydrotreating process is lower than the inlet temperature of the first catalytic zone of the first hydrotreating reactor. For example, the temperature of the liquid (108) of the first hydrotreating process is at least 50°C lower than the inlet temperature of the first catalytic zone of the first hydrotreating reactor.

[0020] No diluent is needed to control the exothermic characteristics of the hydrotreating reaction in the second hydrotreating reactor. Therefore, hydrocarbon diluents may not be present in the second hydrotreating reactor, i.e., in some cases, hydrocarbon diluents are not introduced into the second hydrotreating reactor (102).

[0021] The degree of hydrodeoxygenation and hydronitrogenation in the first hydrotreatment reactor can be controlled in such a way that the temperature rise between the reactor inlet and the reactor outlet in the second hydrotreatment reactor does not exceed 10°C.

[0022] One or more catalytic zones in the first hydrotreatment reactor (101) may have lower hydrodeoxygenation activity than one or more catalytic zones in the second hydrotreatment reactor (102), or one or more catalytic zones in the second hydrotreatment reactor (102) may have higher hydrodeoxygenation activity than one or more catalytic zones in the first hydrotreatment reactor (101).

[0023] The hydrogen-rich gas (120) used in the second hydrogenation reactor (102) may contain nitrogen impurities of less than or equal to 5 wppm, in terms of elemental nitrogen.

[0024] The inlet temperature and pressure of the first hydrogenation treatment reactor (101) can be 200-400°C and 10-150 bar, for example 250-380°C and 20-120 bar, for example 280-360°C and 30-100 bar.

[0025] The first hydrogenation reactor (101) may include at least three catalytic zones or at most three catalytic zones, such as one, two or three catalytic zones.

[0026] The catalytic zone of the first hydrogenation reactor may contain one or more catalysts selected from hydrides on a support, such as catalysts selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. For example, the catalytic zone may contain one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo on a support (e.g., an alumina support).

[0027] The first hydrogenation reactor (101) can process hydrogenation in 0.5-3 h- 1WHSV within the range; and H2 flow downflow operation with a feed of 350-900 Nl H2 / l.

[0028] The inlet temperature and pressure of the second hydrogenation reactor (102) can be 250-450°C and 10-150 bar, for example 300-430°C and 20-120 bar, for example 330-410°C and 30-100 bar.

[0029] The second hydrogenation reactor (102) may have a single catalytic zone.

[0030] The catalytic zone of the second hydrogenation reactor may contain one or more catalysts selected from hydrides on a support, such as catalysts selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. For example, the catalytic zone may contain one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo on a support (e.g., an alumina support).

[0031] The second hydrogenation reactor (102) can process hydrogenation in 0.5-3 h- 1 WHSV within the range; and H2 flow downflow operation with a feed of 350-900 Nl H2 / l.

[0032] The inlet temperature and pressure of the first isomerization reactor (103) can be 280-370°C and 20-50 bar.

[0033] The catalytic zone of the first isomerization reactor may contain one or more catalysts, which comprise a Group VIII metal on a support, wherein the support may be selected from silica, alumina, clay, titanium oxide, boron oxide, or zirconium oxide, which may be used alone or as a mixture. For example, the support may be silica and / or alumina.

[0034] In addition, one or more catalysts may further include molecular sieves, such as zeolites.

[0035] The first isomerization reactor (103) can operate in 0.5-1 h- 1 WHSV within the range; and H2 flow downflow operation with 300-500 Nl H2 / l feed.

[0036] The first isomerization liquid can be isomerized to such an extent that the ratio of isoalkanes to n-alkanes is greater than 1, for example, 1 to 2.5.

[0037] The inlet stream for hydrotreating can have nitrogen impurities of 100 to 500 wppm or higher.

[0038] The effluent (106) from the first hydrotreating reactor can have 100 to 500 wppm or higher nitrogen impurities. Attached Figure Description

[0039] Figure 1 A process scheme according to the present invention is shown, comprising a first hydrogenation reactor (101), a second hydrogenation reactor (102), and a first isomerization reactor (103).

[0040] Figure 2 A comparative process scheme having a first hydrogenation reactor A (201) and a first isomerization reactor A (203) not according to the present invention is shown.

[0041] Figure 3 A comparative process scheme not according to the invention is shown, comprising a first hydrogenation reactor B (301), a second hydrogenation reactor B (302), and a first isomerization reactor B (303). Detailed Implementation

[0042] In describing embodiments of the invention, specific terminology will be used for clarity. However, the invention is not limited to the specific terminology chosen so far, and it should be understood that each specific term includes all technical equivalents that operate in a similar manner to achieve a similar purpose. When referring to the amount of nitrogen content, unless otherwise stated, it is intended to be nitrogen content expressed as elemental nitrogen.

[0043] This invention relates to a method for preparing hydrocarbons from oxygen-containing hydrocarbon feedstocks having nitrogen impurities of 500 wppm or higher (based on elemental nitrogen), the method comprising: - A first hydrotreating reactor (101) includes at least one catalytic zone (105), wherein a hydrotreating inlet stream containing an oxygenated hydrocarbon feedstock (104) and optionally a hydrocarbon diluent (126) is introduced into the catalytic zone along with a hydrogen-rich gas (120) at an inlet temperature and pressure that at least causes hydrodeoxygenation and hydrodenitrogenation, to achieve a level where the effluent (106) from the first hydrotreating reactor is primarily composed of hydrocarbons, wherein the hydrotreating inlet stream has 100 wppm or higher of nitrogen impurities, and wherein the oxygenated hydrocarbon feedstock has been converted to hydrocarbons of ≥95%; - The effluent (106) from the first hydrotreating reactor undergoes a first separation stage (107), wherein at least a portion of the effluent (106) is separated into a first gaseous fraction (121) and a first hydrotreating liquid (108), wherein the first hydrotreating liquid contains greater than or equal to 95 wt% hydrocarbons and greater than 1 wppm nitrogen; - At an inlet temperature (higher than the inlet temperature in the first hydrotreating reactor) and pressure that cause hydrodeoxygenation and hydrodenitrogenation, at least a portion of the first hydrotreating liquid (108) and hydrogen-rich gas (120) are introduced into a second hydrotreating reactor (102), the second hydrotreating reactor including at least one catalytic zone, wherein the first hydrotreating liquid is not mixed with a feed having an oxygen content higher than that of the first hydrotreating liquid, and wherein the first hydrotreating liquid is not mixed with a feed having a nitrogen content higher than that of the first hydrotreating liquid; - The effluent (130) from the second hydrotreating reactor (102) undergoes one or more second separation stages (111) and / or stripping stages (114), wherein the effluent (130) is separated into a second gaseous fraction (113) and a second hydrotreating liquid (112) and / or a stripped hydrotreating liquid (115), wherein the second hydrotreating liquid (112) or the stripped hydrotreating liquid (115) contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 wppm nitrogen, preferably less than or equal to 0.4 wppm nitrogen, for example less than or equal to 0.3 wppm nitrogen (as determined by ASTM D4629), on an elemental nitrogen basis; In other words, the inventors of this invention discovered in a first aspect of the invention that oxygenated hydrocarbons with nitrogen impurities far exceeding those typically present can be effectively hydrogenated in only two hydrogenation reactors, each containing at least one catalytic zone, when ammonia and other low-boiling-point amines are removed from the effluent of a first hydrogenation reactor by separating it into gaseous and liquid phases, and then hydrogenated from the resulting liquid phase in a second hydrogenation reactor, wherein this liquid phase is neither combined with other oxygenated hydrocarbon feeds nor with other feeds having a nitrogen content higher than that of the liquid from the first hydrogenation reactor. The effluent from the second hydrogenation reactor is then separated into a gaseous and a liquid stream from the second hydrogenation reactor; this separation may be a stripping step or a subsequent stripping step, wherein the liquid stream from the second hydrogenation reactor may be stripped with a stripping gas such as hydrogen to reduce the nitrogen content of the stripped liquid to 0.3 wppm or lower.

[0044] This method is used to prepare hydrocarbons from oxygenated hydrocarbon feedstocks. Examples of oxygenated hydrocarbon feedstocks are fatty acids and triglycerides, which are abundant in vegetable oils and animal fats. Renewable sources of oxygenated hydrocarbon feedstocks, such as vegetable oils and animal fats, are well-suited for this process. Most of these vegetable oils and animal fats typically consist of 25 wt% or 40 wt% or more of fatty acids, as free fatty acids or esters of free fatty acids. Examples of esters of free fatty acids are fatty acid glycerides (mono, di, and / or triglycerides) or, for example, fatty acid methyl esters (FAME) or fatty acid ethyl esters (FAE). Accordingly, renewable sources of oxygenated hydrocarbon feedstocks may contain 25 wt% or more of fatty acids or fatty acid esters.

[0045] The renewable properties of carbon-containing compositions (such as raw materials and products) can be achieved by utilizing the carbon in the raw materials. 14 C isotope content and air in 1950 14 The determination is made by comparing the C isotope content. 14 C isotope content can be used as evidence of a renewable source of raw materials or products.

[0046] Compared to carbon atoms from fossil sources, carbon atoms in renewable materials contain more unstable radioactive carbon. 14 C) Atoms. Therefore, through analysis 12 C and 14 The ratio of carbon isotopes can distinguish between carbon compounds derived from biological sources and those derived from fossil sources. Therefore, a specific ratio of isotopes can be used to identify renewable carbon compounds and differentiate them from non-renewable carbon compounds (i.e., fossil carbon compounds). The isotopic ratio does not change during chemical reactions. An example of a suitable method for analyzing the carbon content of biological sources is ASTM D6866 (2020). An example of how ASTM D6866 can be applied to determine the renewable content in fuels is provided in the article by Dijs et al., Radiocarbon, 48(3), 2006, pp. 315-323. For the purposes of this invention, a carbon-containing material, such as a feedstock or product, containing 90% or more modern carbon, such as approximately 100% modern carbon as measured using ASTM D6866, is considered a renewable source.

[0047] Many vegetable oils and animal fats may contain typical amounts of nitrogen impurities, such as 1-100 ppm, and can also be hydrotreated using the method of the present invention. However, the method of the present invention is advantageous from the perspective that hydrotreatment methods can convert oxygenated hydrocarbon feedstocks with high nitrogen impurities, such as nitrogen impurities of 300 wppm to 2500 wppm or higher, for example 500 wppm or higher, for example 800 wppm or higher. For example, oxygenated hydrocarbon feedstocks can have nitrogen impurities up to 1500 wppm, for example 2500 wppm. Examples of oxygenated hydrocarbon feedstocks with high nitrogen impurities are some animal fats, which may have nitrogen impurities of about 1000 wppm, for example in the range of 600 to 1400 wppm. If desired, the oxygenated hydrocarbon feedstock can consist of a mixture of oxygenated hydrocarbons from different sources. For example, 50% palm oil with 23 ppm nitrogen impurities can be mixed with 50% animal fat with 1000 ppm nitrogen impurities to produce an oxygenated hydrocarbon feedstock with 512 ppm nitrogen impurities. Therefore, the oxygenated hydrocarbon feedstock can be selected from vegetable oils, animal fats, or mixtures thereof.

[0048] Nitrogen impurities are measured as elemental nitrogen. One method for measuring elemental nitrogen is ASTM D4629, which is used in the range of 0.3–100 wppm, and another method is ASTM D572, which may be more suitable for values ​​above 100 wppm. In this invention, both methods can be used as needed to measure nitrogen impurities (measured as elemental nitrogen).

[0049] The method involves feeding a hydrotreating inlet stream into a first hydrotreating reactor (101) comprising at least one catalytic zone (105). The hydrotreating inlet stream comprises an oxygenated hydrocarbon feedstock (104), which can be selected as described above, for example, vegetable oils, animal fats, or mixtures thereof containing 300 wppm or higher nitrogen, for example, 500-1500 wppm nitrogen. The hydrotreating inlet stream may optionally contain a hydrocarbon diluent (126). The hydrocarbon diluent may be product recycled or hydrocarbons from fossil or renewable sources. To control the exothermic nature of the hydrotreating reaction, product recycling is typically used, adding the product recycled to the oxygenated hydrocarbon feedstock. If a hydrocarbon diluent is added, the amount added is typically in the range of 1:1 to 4:1 (total hydrocarbon diluent: total oxygenated feedstock). As described above, the hydrocarbon diluent may be from fossil or renewable sources. Some fossil-sourced hydrocarbon feedstocks may contain significant nitrogen impurities. These fossil-sourced hydrocarbon feedstocks may also be part of a hydrocarbon diluent, alone or in combination with other hydrocarbon diluents (multiple types), such as product recycling. For example, hydrocarbon diluents can be a mixture of recycled products and fossil hydrocarbons.

[0050] Using recycled products is advantageous because they typically contain dissolved hydrogen, which is related to the hydrogenation treatment reaction that depends on the hydrogen dissolved in the liquid phase.

[0051] The hydrotreating inlet stream has nitrogen impurities of 100 wppm or higher, for example, 100 to 500 wppm, and / or the effluent (106) from the first hydrotreating reactor can have nitrogen impurities of 100 to 500 wppm or higher. Hydrotreating inlet streams with nitrogen impurities below 100 wppm can also be hydrotreated using the method of the present invention. However, the method of the present invention is advantageous from the perspective that the hydrotreating method can convert oxygenated hydrocarbon feedstocks with high nitrogen impurities without requiring extensive dilution to reduce the total nitrogen impurities in the hydrotreating inlet stream. This is advantageous because extensive dilution reduces the yield of oxygenated hydrocarbon feedstocks during hydrotreating. Alternatively or additionally, the nitrogen content in the effluent (106) from the first hydrotreating reactor, which can have nitrogen impurities of 100 to 500 wppm or higher, can also be measured.

[0052] Regarding the maximum amount of nitrogen impurities that may be present. There will be limitations on how much nitrogen impurity is present as an impurity or how high the level of impurity removal is practically feasible. Therefore, the hydrotreatment inlet stream and / or the effluent (106) from the first hydrotreatment reactor may have nitrogen impurities of up to 500 wppm or less, i.e., the hydrotreatment inlet stream and / or the effluent (106) from the first hydrotreatment reactor may have nitrogen impurities of up to 100 wppm to 500 wppm.

[0053] The hydrotreatment inlet stream, together with hydrogen-rich gas (120), is introduced into a first hydrotreatment reactor (101) comprising at least one catalytic zone (105).

[0054] The hydrogen-rich gas (120) needs to undergo, for example, hydrodeoxygenation (HDO) and hydrodenitrification (HDN) reactions in the first hydrotreatment reactor (101). The hydrogen-rich gas can be, for example, excess hydrogen from the process, which has been purified by one or more purification steps (122), for example, separating it into a fourth gaseous fraction (123) containing water, ammonia, and other light components, followed by amine washing and / or membrane separation. The purity of the hydrogen-rich gas used in the first hydrotreatment reactor is less important than the purity of the hydrogen-rich gas used for stripping before the isomerization reactor or for the second hydrotreatment reactor (102) used in the first isomerization reactor (103), which appropriately contains no active nitrogen, such as ammonia, or nitrogen of less than 0.3-wppm, in elemental nitrogen. Typically, a purity of 95 mol% or higher for the hydrogen-rich gas used in the first hydrotreatment reactor is acceptable, but its hydrogen purity may also be less than 95 mol%. Make-up hydrogen may also be mixed to form a hydrogen-rich gas, or the hydrogen-rich gas may consist entirely of the make-up gas.

[0055] The first hydrotreating reactor (101) is a vessel capable of accommodating at least one catalytic zone. In this invention, a trickle bed reactor is particularly suitable. A trickle bed reactor involves the downward movement of the hydrotreating inlet stream while it contacts hydrogen in a co-current or counter-current manner. An example of a trickle bed reactor is an adiabatic trickle bed reactor.

[0056] The first hydrogenation reactor (101) includes at least one catalytic zone (105). The simplest form of such a catalytic zone can be a fixed bed of catalyst particles. It can also be multiple fixed beds having the same or different catalyst particles, or it can be multiple layers of catalyst particles with different activities and / or compositions.

[0057] The first hydrogenation reactor (101) may include at least three catalytic zones or at most three catalytic zones, such as one, two or three catalytic zones.

[0058] The hydrogenation inlet stream, together with hydrogen-rich gas (120), is introduced into a first hydrogenation reactor (101) comprising at least one catalytic zone (105).

[0059] At inlet temperatures and pressures that cause at least hydrodeoxygenation and hydronitrogenation, the hydrotreatment inlet stream, together with hydrogen-rich gas (120), is introduced into the catalytic zone to the extent that the effluent (106) from the first hydrotreatment reactor mainly contains hydrocarbons. There are many different combinations of inlet temperature and pressure, which will cause HDO and HDN to reach the extent that oxygen is removed from oxygenated hydrocarbons, thus producing water as a byproduct, and to reach the extent that nitrogen impurities are removed from oxygenated hydrocarbons, thus producing ammonia as a byproduct and the main hydrocarbon products.

[0060] For example, the inlet temperature and pressure of the first hydrogenation treatment reactor (101) can be 200-400°C and 10-150 bar, such as 250-380°C and 20-120 bar, such as 280-360°C and 30-100 bar.

[0061] The routine work of those skilled in the art is to select various combinations of temperatures and pressures that cause at least hydrodeoxygenation and hydrodenitrification to achieve a level in which the effluent (106) from the first hydrotreatment reactor primarily contains hydrocarbons, wherein the oxygenated hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons, suitably greater than or equal to 98% hydrocarbons, wherein less than or equal to 2% oxygenated hydrocarbon feedstock is present.

[0062] In the same way that those skilled in the art can select various combinations of temperature and pressure, they can also select one or more suitable catalysts for one or more catalytic zones of the first hydrogenation reactor.

[0063] For example, the catalytic zone of the first hydrotreating reactor may contain one or more catalysts selected from hydrides on a support, such as catalysts selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. For example, the catalytic zone may contain one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo on a support (e.g., an alumina support). When the catalyst is selected from Ni, Co, Mo, Ru, Rh, W, or any combination thereof, the catalyst is typically sulfided, and a sulfur source is added to or present in the hydrotreating inlet stream and / or the hydrogen-rich gas.

[0064] The first hydrogenation reactor (101) can process hydrogenation in 0.5-3 h- 1 For example, 0.5-1.5 h- 1 The range of WHSV and 350-2100 Nl H2 / l feed, such as 500-1500 Nl H2 / l feed for H2 flow downflow operation.

[0065] More general reaction conditions for the first hydrotreating step may include a trickle bed reactor as the first hydrotreating reactor, the first hydrotreating reactor including a catalyst zone comprising a molybdenum-containing supported hydrotreating catalyst, wherein the hydrotreating is carried out in the presence of hydrogen at a temperature of 200-400°C and a pressure of 10-150 bar, wherein the WHSV is maintained at 0.5-3 h⁻¹. 1 Within the range of 300-2100 Nl H2 / l feed H2 flow.

[0066] The first hydrotreating step produces a first hydrotreating effluent (106) containing excess hydrogen, water vapor from HDO, CO and CO2 from the decarboxylation / decarbonylation of carboxylic acids in the oxygen-containing hydrocarbon feed, and gaseous components in the form of H2S. Finally, NH3 is produced from the HDN reaction. The ammonia (NH3) produced in the method of the present invention will be much greater than during the hydrotreating of a normal feed (e.g., palm oil with a typical amount of 1-100 ppm nitrogen), for example, it can have 23 ppm nitrogen. The inventors have surprisingly found that when the hydrotreating effluent passes through a second hydrotreating step with the addition of supplemental hydrogen, the increased amount of ammonia in the hydrotreating effluent leads to the recombination of nitrogen. That is, the inventors have found that even after stripping with hydrogen, the second hydrotreating effluent from this second hydrotreating step contains 2-5 ppm nitrogen, i.e., it is desirable to remove nitrogen as completely as possible even before contact with the isomerization catalyst, and it is not possible to simply reduce the amount of nitrogen below 2-5 ppm even after stripping. This was quite unexpected, as the second hydrotreating step is carried out at a higher temperature, with particular expectation of a deeper HDO and HDN hydrotreating process to remove oxygen and nitrogen more extensively from the effluent of the first hydrotreating step. Furthermore, it was anticipated that the hydrocarbons already formed would be inert to any reaction with ammonia, and that even under the conditions of the second hydrotreating step, ammonia should react to form amines or amides, and even if there were a theoretical possibility of forming such nitrogen compounds, these formed compounds would again undergo hydrodenitrification (HDN) to remove ammonia. However, surprisingly, it was found that the nitrogen compounds formed in the second hydrotreating reactor did not disappear again under the hydrotreating conditions. These compounds included secondary and tertiary amides.

[0067] As is known in the art, nitrogen can deactivate isomerization catalysts, which is why ammonia contained in the effluent entering the isomerization reactor is typically stripped by a stripping gas, thereby replacing / stripping any dissolved ammonia and removing any residual nitrogen. As the inventors discovered in Comparative Example 1, the absence of a separation step between the first and second hydrotreating reactors during hydrotreating of oxygenated hydrocarbon feedstocks results in a higher nitrogen content in the feed to the isomerization reactor, which in turn leads to a lower yield of aviation fuel fractions with a cloud point of -40°C or lower.

[0068] An unexpected finding was that ammonia in the effluent from the first hydrotreating caused nitrogen recombination in the second hydrotreating reactor, and these nitrogen compounds were also unexpectedly resilient to HDN conditions, rendering normal removal of any residual ammonia from the stripping step prior to isomerization ineffective. This is surprising to the inventors who modified the hydrotreating process by including a separation stage after the first hydrotreating reactor, such that the effluent from the first hydrotreating reactor undergoes a first separation stage (107), in which at least a portion of the first hydrotreating effluent (106) is separated into a first gaseous fraction (121) and a first hydrotreating liquid (108).

[0069] The first separation stage (107) can be, for example, one or more high-pressure or low-pressure separators, which are known in the art to separate the effluent (106) of the first hydrotreating process into a first gaseous fraction (121) and a first hydrotreating liquid (108). Hydrogen stripping can also be used for separation (not shown in the figure). The separation stage can be entirely a high-temperature separation stage, in which the effluent is not actively cooled. From the viewpoint that less heating is required in the second hydrotreating step, it is advantageous not to cool the effluent of the first hydrotreating process. It may also be advantageous if the separated first hydrotreating liquid is used for product recycling to dilute the oxygenated hydrocarbon feedstock.

[0070] The separation stage may also include cryogenic separation, wherein the hydrotreated effluent is actively cooled, for example, by a heat exchanger, as this is advantageous from the viewpoint of separating as much ammonia as possible from the liquid of the first hydrotreatment. Therefore, cooling can be applied during the separation stage of the effluent (106) of the first hydrotreatment to the extent that the temperature of the liquid (108) of the first hydrotreatment is below the inlet temperature of the first catalytic zone of the first hydrotreatment reactor. For example, the temperature of the liquid (108) of the first hydrotreatment is at least 50°C below the inlet temperature of the first catalytic zone of the first hydrotreatment reactor, for example, at least 100°C lower than the inlet temperature of the first hydrotreatment reactor. The cold separation of the effluent of the first hydrotreatment can be carried out, for example, at a temperature of 120 to 200°C.

[0071] The entire amount of the effluent (106) from the first hydrotreating process can be separated, or at least a portion of the effluent (106) from the first hydrotreating process can be separated. For example, the effluent from the first hydrotreating process can be split into two streams, wherein the first stream is separated into liquid and gaseous fractions of the first hydrotreating process as described above, and wherein the second stream is used as a hydrocarbon diluent without any separation. In addition to hydrocarbons, the second stream will also include excess hydrogen and all gaseous impurities, including ammonia, which will be reintroduced into the first hydrotreating reactor.

[0072] The entire amount of the first hydrotreating effluent (106) can be separated to prevent the accumulation of ammonia in the first hydrotreating reactor or to prevent the addition of more ammonia to the first hydrotreating reactor (when the first hydrotreating effluent is used as product recycling), which can react with oxygenated hydrocarbons to form other nitrogen compounds that may subsequently be present in the first hydrotreating effluent.

[0073] In the first separation stage (107), the effluent (106) of the first hydrotreating is separated into a first gaseous fraction (121) and a first hydrotreating liquid (108). The first gaseous fraction (121) will contain excess hydrogen, water vapor from HDO, CO and CO2 from the decarboxylation / decarbonylation of carboxylic acids in the oxygen-containing hydrocarbon feed, and H2S. Finally, NH3 is produced from the HDN reaction. The first hydrotreating liquid (108) will contain greater than or equal to 90 wt% hydrocarbons, the remainder being heteroatom-containing hydrocarbons, such as unreacted oxygen-containing hydrocarbons. It is desirable for the hydrotreating to be as complete as possible, i.e., the first hydrotreating liquid (108) contains greater than or equal to 95 wt% hydrocarbons, for example, greater than or equal to 98 wt% hydrocarbons. However, complete hydrotreating of the hydrotreating inlet stream without increasing the severity of the reaction conditions is not always feasible or possible, which may lead to catalyst coking and other undesirable side effects. Therefore, the conversion rate can make the liquid (108) of the first hydrogenation treatment also contain less than or equal to 99 wt% hydrocarbons, that is, the hydrogenation inlet stream is hydrogenated to the extent that the liquid (108) of the first hydrogenation treatment contains 95 wt% to 99 wt% hydrocarbons.

[0074] The remaining components of the liquid from the first hydrogenation treatment will be heteroatom-containing hydrocarbons, such as oxygen-containing or nitrogen-containing hydrocarbons. Due to the very high initial nitrogen impurities, nitrogen will still be retained to some extent in the liquid from the first hydrogenation treatment, which may contain more than 1 wppm of nitrogen (as elemental nitrogen), for example, more than 5 wppm, and up to 100 wppm.

[0075] The first hydrogenated liquid (108) containing, for example, 5-100 wppm of nitrogen impurities, or at least a portion thereof, is introduced into the second hydrogenated reactor (102) together with hydrogen-rich gas (120).

[0076] The hydrogen-rich gas (120) needs to undergo reactions such as hydrodeoxygenation (HDO) and hydrodenitrification (HDN) not only in the first hydrotreatment reactor (101) as described above, but also in the second hydrotreatment reactor (102). The hydrogen-rich gas can be, for example, excess hydrogen from the process, which has been purified by one or more purification steps (122), such as separating it into a fourth gaseous fraction (123) containing water, ammonia, and other light components, followed by amine washing and / or membrane separation. The purity of the hydrogen-rich gas used in the first hydrotreatment reactor is less important than the purity of the hydrogen-rich gas used for stripping before the isomerization reactor or for use in the second hydrotreatment reactor (102) in the first isomerization reactor (103).

[0077] The hydrogen-rich gas used in the second hydrotreating reactor typically has a purity of 90 mol%, usually 95 mol% or higher, and may contain gaseous hydrocarbons. Ideally, the hydrogen-rich gas used in the second hydrotreating reactor has little or no active nitrogen, such as ammonia, in order to minimize the risk of nitrogen recombination into the effluent (130) of the second hydrotreating reactor. Specifically, when the hydrogen-rich gas (120) used in the second hydrotreating reactor is mixed with the liquid (108) of the first hydrotreating reactor to form the feed (110) for the second hydrotreating reactor (102), the nitrogen content in the hydrogen-rich gas (120) used in the second hydrotreating reactor should ideally not lead to an increase in the nitrogen content of the liquid phase of the feed (110) for the second hydrotreating reactor (102). 。

[0078] Therefore, the hydrogen-rich gas (120) used in the second hydrogenation reactor (102) may contain nitrogen impurities of less than or equal to 10 wppm or lower, for example, nitrogen impurities of less than or equal to 5 wppm (in elemental nitrogen), for example, nitrogen impurities of less than or equal to 1 wppm.

[0079] Hydrogen-rich gas can be purified excess hydrogen, a process known as hydrogen recirculation, if its mass is sufficient. It can also be fresh hydrogen that has not yet been used in the process, and it can be a mixture of hydrogen recirculation and fresh hydrogen.

[0080] As those skilled in the art will understand, when referring to nitrogen impurities, it is intended to encompass nitrogen impurities that, under hydrogenation or hydroisomerization conditions, can be considered to have reacted to form new bonds, i.e., non-inert or reactive nitrogen. For example, according to the invention, nitrogen capable of binding to the products and intermediates of the invention, such as effluents from the first or second hydrogenation treatment, or effluents from the first isomerization, is considered a nitrogen impurity. As used in the invention, nitrogen gas (N2) should not fall within the scope of the term "nitrogen impurity." Nitrogen impurities can be determined using elemental analysis and include organic nitrogen, ammonia, and ammonium.

[0081] The second hydrotreating reactor (102) is a vessel capable of accommodating at least one catalytic zone. In this invention, a trickle bed reactor is particularly suitable. A trickle bed reactor involves the downward movement of the hydrotreating inlet stream while it contacts hydrogen in a co-current or counter-current manner. An example of a trickle bed reactor is an adiabatic trickle bed reactor.

[0082] The second hydrogenation reactor (102) includes at least one catalytic zone. The simplest form of such a catalytic zone can be a fixed bed of catalyst particles. It can also be multiple fixed beds with the same or different catalyst particles, or it can be multiple layers of catalyst particles with different activities and / or compositions.

[0083] The second hydrogenation reactor (102) may have a single catalytic zone.

[0084] The liquid (108) of the first hydrotreating process is introduced together with hydrogen-rich gas (120) into the second hydrotreating reactor (102), wherein it is contacted with at least one catalytic zone at an inlet temperature and pressure that causes at least hydrodeoxygenation and hydrodenitrogenation, to the extent that the liquid of the second hydrotreating process contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 wppm nitrogen, preferably less than or equal to 0.4 wppm nitrogen, for example less than or equal to 0.3 wppm nitrogen (as determined by ASTM D4629) (in elemental nitrogen).

[0085] Specifically, the nitrogen content of the liquid (112) after the second hydrogenation treatment is lower than that of the liquid (108) after the first hydrogenation treatment.

[0086] Before or during hydrogenation in the second hydrogenation reactor, it is neither required nor intended to dilute the liquid from the first hydrogenation process with any diluent such as hydrocarbons. Instead, the liquid from the first hydrogenation process is used as the feed to the second hydrogenation reactor. However, the liquid from the first hydrogenation process may be mixed with another hydrocarbon feed, provided that the liquid from the first hydrogenation process is not mixed with a feed having an oxygen content higher than that of the liquid from the first hydrogenation process and wherein the liquid from the first hydrogenation process is not mixed with a feed having a nitrogen content greater than or equal to 5 wppm. No diluent is required to control the exothermic characteristics of the hydrotreating reaction in the second hydrotreating reactor. Therefore, diluents such as hydrocarbon diluents may not be present in the second hydrotreating reactor; that is, in some cases, hydrocarbon diluents are not introduced into the second hydrotreating reactor (102).

[0087] There are many different combinations of inlet temperature and pressure that will cause HDO and HDN to reach the extent that oxygen is removed from the remaining oxygenated hydrocarbons, thus producing water as a byproduct, and nitrogen impurities are further reduced compared to the liquid of the first hydrogenation treatment, thus producing ammonia as a byproduct, and the liquid of the second hydrogenation treatment (112) contains a lower amount of nitrogen impurities than the liquid of the first hydrogenation treatment (108).

[0088] For example, the inlet temperature and pressure of the second hydrogenation treatment reactor (102) can be 250-450°C and 10-150 bar, such as 300-430°C and 20-120 bar, such as 330-410°C and 30-100 bar.

[0089] To achieve a deeper HDO and HDN reaction, the inlet temperature of the first catalytic zone of the second hydrotreating reactor can be increased compared to the inlet temperature of the first catalytic zone of the first hydrotreating reactor. For example, the inlet temperature of the second hydrotreating reactor can be 10-15°C higher than that of the first hydrotreating reactor, or even higher.

[0090] Since the amount of oxygen-containing hydrocarbons in the liquid of the first hydrotreating reactor is significantly less than that in the hydrotreating inlet stream of the first hydrotreating reactor, this means that the temperature rise on the catalyst bed is not as high as that in the catalyst bed of the first hydrotreating reactor due to the occurrence of less exothermic reaction.

[0091] For example, the temperature rise between the reactor inlet and reactor outlet of the second hydrotreating reactor may be small, such as no more than 35°C, or it can be considered to be 50% or less of the temperature rise in the first hydrotreating reactor.

[0092] Therefore, the degree of hydrodeoxygenation and hydronitrogenation in the first hydrotreatment reactor can be controlled such that the temperature rise between the reactor inlet and outlet in the second hydrotreatment reactor does not exceed 10°C. This can be controlled by ensuring sufficient conversion of oxygen-containing hydrocarbon feed in the first hydrotreatment reactor, leaving only a small amount of hydrocarbons with heteroatoms (e.g., oxygen and nitrogen) in the liquid from the first hydrotreatment, which will subsequently result in a smaller temperature rise due to the amount of residual material undergoing the exothermic hydrotreatment reaction.

[0093] To increase the hydrotreating activity in the second hydrotreating reactor, the temperature can be increased as described above to achieve deeper HDO and HDN reactions. Hydrotreating activity can also be increased by ensuring that one or more catalytic zones in the second hydrotreating reactor (102) have higher hydrodeoxygenation activity than one or more catalytic zones in the first hydrotreating reactor (101).

[0094] Catalytic activity can also be initiated at the same rate in both the first and second hydrotreatment reactors, for example, by using catalysts with the same activity in both reactors. Over time, one or more catalytic zones in the first hydrotreatment reactor will deactivate faster than one or more catalytic zones in the second hydrotreatment reactor because a more impure feed, i.e., the hydrotreatment inlet stream, is supplied to the first hydrotreatment reactor, while a purer feed, i.e., the liquid from the first hydrotreatment, is supplied to the second hydrotreatment reactor. Therefore, one or more catalytic zones in the first hydrotreatment reactor (101) have lower hydrodeoxygenation activity than one or more catalytic zones in the second hydrotreatment reactor (102). Catalytic activity can be measured compared to fresh catalyst.

[0095] In the same way that those skilled in the art can select various combinations of temperature and pressure to induce deeper HDO and HDN reactions, they can also select one or more suitable catalysts and other conditions for one or more catalytic zones of the first hydrotreating reactor.

[0096] The catalytic zone of the second hydrotreating reactor may contain one or more catalysts selected from hydrides on a support, such as catalysts selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. For example, the catalytic zone may contain one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo on a support (e.g., alumina support). When the catalyst is selected from Ni, Co, Mo, Ru, Rh, W, or any combination thereof, the catalyst is typically sulfided, and a sulfur source is added to or present in the hydrotreating inlet stream and / or the hydrogen-rich gas.

[0097] The second hydrogenation reactor (102) can process hydrogenation in 0.5-3 h- 1 For example, 0.5-1.5 h- 1 The range of WHSV and 350-2100 Nl H2 / l feed, such as 500-1500 Nl H2 / l feed for H2 flow downflow operation.

[0098] More general reaction conditions for the second hydrotreating step may include a trickle bed reactor serving as the second hydrotreating reactor, the second hydrotreating reactor including a catalyst zone comprising a molybdenum-containing supported hydrotreating catalyst, wherein the hydrotreating is carried out in the presence of hydrogen at a temperature of 250-400°C and a pressure of 10-150 bar, wherein the WHSV is maintained at 0.5-3 h⁻¹. 1 Within the range of 500-2100 Nl H2 / l feed H2 flow.

[0099] The effluent (130) from the second hydrotreating reactor (102) undergoes one or more second separation stages (111) and / or stripping stages (114), wherein the effluent (130) from the second hydrotreating reactor is separated into a second gaseous fraction (113) and a second hydrotreating liquid (112) and / or a stripped hydrotreating liquid (115).

[0100] The second separation stage (111) can be, for example, one or more high-pressure or low-pressure separators, which are known in the art to be capable of separating the effluent (130) from the second hydrotreating process into a second gaseous fraction (113) and a second hydrotreating liquid (112). The separation stage can be entirely a high-temperature separation stage, in which the effluent is not actively cooled. It is advantageous not to cool the second hydrotreating effluent from the perspective of requiring less heating in any subsequent steps (e.g., the first isomerization step). It may also be advantageous if the separated second hydrotreating liquid is used for product recycling to dilute the oxygenated hydrocarbon feedstock.

[0101] The stripping stage (114) is a stripping tower that uses a gas (usually hydrogen) to remove impurities from the effluent (130) or liquid (112) of the second hydrotreating process. Hydrogen is typically used as the stripping gas because the stripping stage serves both to remove impurities and to ensure that a certain amount of hydrogen is dissolved in the liquid (112) of the second hydrotreating process and / or the stripped liquid (115), which is advantageous if these liquids are fed, for example, to a hydroisomerization stage such as the first isomerization reactor (103). If stripping is used, the nitrogen content of the liquid (112) of the second hydrotreating process and the liquid (115) of the stripped liquid (115) is lower than the nitrogen concentration of the liquid (108) of the first hydrotreating process.

[0102] Therefore, the effluent (130) from the second hydrotreatment reactor (102) can be stripped with stripping gas (e.g., hydrogen) from the stripping stage (114) so ​​that the stripped hydrotreated liquid (115) has less than or equal to 0.4 wppm of nitrogen, for example less than or equal to 0.3 wppm of nitrogen (ASTM D4629 detection limit) (in elemental nitrogen).

[0103] If necessary, for example from the perspective of further purification of the effluent (130) from the second hydrotreatment reactor (102), a second separation stage (111) may be performed first, in which the effluent (130) from the second hydrotreatment reactor (102) is separated into a second gaseous fraction (113) and a second hydrotreated liquid (112), and then the second hydrotreated liquid (112) is stripped in a stripping stage (114) with a stripping gas (e.g., hydrogen) so that the stripped hydrotreated liquid (115) has less than or equal to 0.4 wppm of nitrogen, for example less than or equal to 0.3 wppm of nitrogen (ASTM D4629 detection limit) (in elemental nitrogen).

[0104] The use of a hydrogen stripping stage is advantageous in order to both remove impurities and ensure that a certain amount of hydrogen is dissolved in the liquid phase, as described above. The stripping stage is particularly useful when the liquid is brought to, for example, a hydroisomerization stage, such as the first isomerization reactor (103).

[0105] However, a second separation stage (111) comprising one or more high-pressure or low-pressure separators may also be used, as described above. This may be relevant when the liquid from the second hydrogenation treatment is used as its own product or as a process recycle.

[0106] The liquid from the second hydrogenation treatment can be used as its own product or as a process recycling.

[0107] The liquid undergoing the second hydrotreating can also be isomerized in a first isomerization reactor (103) comprising at least one catalytic zone, wherein the liquid undergoing the second hydrotreating and a hydrogen-rich gas (H2) having less than or equal to 1 ppm (mol / mol) of nitrogen (in elemental nitrogen) are introduced into the catalytic zone at an inlet temperature and at a pressure that at least causes hydroisomerization to produce the first isomerization effluent (116).

[0108] Hydrogen-rich gas (120) is also necessary for hydrodeoxygenation (HDO) and hydrodenitrification (HDN) in the first hydrogenation reactor (101) and the second hydrogenation reactor (102) as described above, but is also necessary in the first isomerization reactor (103).

[0109] The hydrogen-rich gas can be, for example, excess hydrogen from the process, which has been purified by one or more purification steps (122), such as separating it into a fourth gaseous fraction (123) containing water, ammonia, and other light components, followed by amine washing and / or membrane separation. The purity of the hydrogen-rich gas used in the first isomerization reactor is important.

[0110] The hydrogen-rich gas used in the first isomerization reactor has a purity of 95% or higher. This is because it is designed to minimize the risk of poisoning in the catalytic zone of the first isomerization reactor. Therefore, the hydrogen-rich gas used in the second hydrotreating reactor ideally has little or no active nitrogen, such as ammonia.

[0111] Therefore, the hydrogen-rich gas (120) used in the first isomerization reactor (103) may contain nitrogen impurities of less than or equal to 1 ppm (mol / mol) (based on elemental nitrogen). The hydrogen-rich gas may be purified excess hydrogen, i.e., so-called hydrogen recirculation, if its mass is sufficient. The hydrogen-rich gas may also be fresh hydrogen that has not yet been used in the process, and it may be a mixture of hydrogen recirculation and fresh hydrogen.

[0112] As those skilled in the art will understand, when referring to nitrogen impurities, it is intended to encompass nitrogen impurities that, under hydrotreatment or hydroisomerization conditions, can be considered to have reacted to form new bonds, i.e., non-inert or reactive nitrogen. For example, according to the invention, nitrogen capable of binding to the products and intermediates of the invention, such as effluents from the first or second hydrotreatment, or from the first isomerization effluent, is considered a nitrogen impurity. As used in the invention, nitrogen gas (N2) should not fall within the scope of the term "nitrogen impurity." When the isomerization catalyst comprises a noble metal catalyst, such as a catalyst containing Pd or Pt, sulfur impurities (if present) should also be low.

[0113] The first isomerization reactor (103) is a vessel capable of housing at least one catalytic zone. In this invention, a trickle bed reactor is particularly suitable. A trickle bed reactor involves the downward movement of the feed while it contacts hydrogen in a co-current or counter-current manner. An example of a trickle bed reactor is an adiabatic trickle bed reactor.

[0114] The first isomerization reactor (103) includes at least one catalytic zone. The simplest form of such catalytic zone can be a fixed bed of catalyst particles. It can also be multiple fixed beds having the same or different catalyst particles, or it can be multiple layers of catalyst particles with different activities and / or compositions. The first isomerization reactor (103) may have a single catalytic zone.

[0115] The second hydrotreated liquid (112) or the stripped hydrotreated liquid (115) is introduced together with hydrogen-rich gas (120) into the first isomerization reactor (103), wherein it is contacted with at least one catalytic zone at an inlet temperature and pressure that causes at least hydroisomerization to produce a first isomerization effluent (116) to such an extent that the liquid portion of the first isomerization effluent (116) contains greater than or equal to 30 wt% of branched hydrocarbons and / or an increase of greater than or equal to 30 wt% of branched hydrocarbons compared to the second hydrotreated liquid.

[0116] There are many different combinations of inlet temperature and pressure that will cause hydroisomerization to the extent that the first isomerized effluent (116) contains greater than or equal to 30 wt% branched hydrocarbons, and / or the branched hydrocarbons increase by greater than or equal to 30 wt% compared to the liquid from the second hydrotreatment.

[0117] For example, the inlet temperature and pressure of the first isomer reactor (103) can be 250-400°C and 20-50 bar, such as 280-370°C and 20-50 bar, or 295-370°C and 20-50 bar.

[0118] The catalytic zone of the first isomerization reactor may contain one or more catalysts comprising a Group VIII metal on a support, wherein the support may be selected from silica, alumina, clay, titanium oxide, boron oxide, or zirconium oxide, which may be used alone or as a mixture. For example, the support may be silica and / or alumina. For example, the Group VIII metal may be Pd or Pt. In addition, one or more catalysts may also include molecular sieves, such as zeolites.

[0119] The first isomerization reactor (103) can operate in 0.5-3 h- 1 WHSV within the range; and 150-800 Nl H2 / l feed, for example 0.5-1 h- 1 H2 flow; and operation under H2 flow with 300-500 Nl H2 / l feed.

[0120] Those skilled in the art know how to manipulate the above conditions to obtain a degree of hydroisomerization, wherein the liquid portion of the first isomerization effluent (116) contains more branched hydrocarbons compared to the liquid portion of the second hydrotreatment. For example, reaching a level where the liquid portion of the first isomerization effluent (116) contains greater than or equal to 30 wt% branched hydrocarbons, and / or an increase in branched hydrocarbons greater than or equal to 30 wt% compared to the liquid portion of the second hydrotreatment.

[0121] The first isomerization liquid can also be isomerized to such an extent that the ratio of isoalkanes to n-alkanes is greater than 1, for example, 1 to 4.5, or 1 to 2.5.

[0122] The degree of isomerization is typically measured as the difference between the cloud points of the feed and the product; in this case, it is the difference between the liquid from the second hydrotreating process and the liquid portion of the first isomerized effluent, where the magnitude of the cloud point reduction determines the degree of hydroisomerization. Therefore, the first isomerized liquid can be isomerized to such an extent that the cloud point decreases by 10°C or more from the liquid from the second hydrotreating process to the liquid portion of the first isomerized effluent.

[0123] Generally, a lower cloud point is considered better, as this will result in good low-temperature flow properties. However, under hydroisomerization conditions, a certain degree of hydrocracking also exists. In the art, there are often points where hydrocracking becomes too extensive, making it possible for liquid product losses to outweigh the lower cloud point. The catalyst and any impurities contained therein, as well as the hydroisomerization conditions, are parameters that can affect the degree of hydroisomerization and hydrocracking. Referring to Comparative Example 1 and Example 1, it can be seen that the nitrogen impurities (0.6-2.9 wppm) before entering the isomerization reactor in Comparative Example 1 are much higher than those in Example 1 (less than or equal to 0.3 wppm). This difference in nitrogen content in the isomerization reactor not only affects the yield of a particular fuel fraction but also significantly affects its low-temperature flow properties.

[0124] For example, the second hydrotreated liquid (112) or the second hydrotreated effluent (130) is subjected to a stripping stage (114), wherein the second hydrotreated liquid or the second hydrotreated effluent is stripped with stripping gas (H2), such that the stripped hydrotreated liquid (115) has less than or equal to 0.4 wppm of nitrogen, for example less than or equal to 0.3 wppm of nitrogen (as determined by ASTM D4629) (in elemental nitrogen), and has a lower nitrogen content compared to the second hydrotreated liquid (112); the stripped hydrotreated liquid (115) may be subjected to an isomerization step in a first isomerization reactor (103) comprising at least one catalytic zone, wherein the stripped hydrotreated liquid (115) and the second hydrotreated liquid (115) having less than or equal to 1 wppm of nitrogen are stripped. A hydrogen-rich gas (120) of ppm (mol / mol) nitrogen (based on elemental nitrogen) is introduced into the catalytic zone at a temperature and pressure that at least causes hydroisomerization to produce a first isomerized effluent (116); wherein the first isomerized effluent (116) from the first isomerization reactor (103) undergoes a third separation stage (117), wherein the first isomerized effluent (116) is separated into a third gaseous fraction (118) and a first isomerized liquid (119), wherein the first isomerized liquid contains greater than or equal to 30 wt% branched hydrocarbons.

[0125] More general reaction conditions for the first isomerization step may include a trickle-bed reactor as the first isomerization reactor, comprising a catalyst zone including a supported hydrogenation catalyst containing W, Pt, or Pd, and zeolite, wherein the hydroisomerization is carried out in the presence of hydrogen at a temperature of 295-370°C and a pressure of 20-50 bar, wherein WHSV 0.5-1.5 h⁻¹ 1 Within the range, and with an H2 flow of 50-800 Nl H2 / l feed, the cloud point of the liquid portion from the second hydrogenation treatment to the liquid portion of the first isomerization effluent is reduced by 10°C or more.

[0126] The first isomerized effluent (116) from the first isomerization reactor (103) undergoes a third separation stage (117), wherein the first isomerized effluent (116) is separated into a third gaseous fraction (118) and a first isomerized liquid (119).

[0127] The third separation stage (117) may be, for example, one or more high-pressure or low-pressure separators, which are known in the art to be capable of separating the first isomerized effluent (116) into a third gaseous fraction (118) and a first isomerized liquid (119). The third separation stage (117) may also be distillation, although it is generally advantageous to separate the gaseous fraction from the liquid fraction prior to distillation.

[0128] As described above, the first isomerized liquid contains greater than or equal to 30 wt% branched hydrocarbons, and / or the branched hydrocarbon content increases by greater than or equal to 30 wt% compared to the liquid treated with the second hydrogenation.

[0129] The first isomerized effluent (116) or the first isomerized liquid (119) may undergo a distillation stage to produce one or more product fractions. Such fractionation is well known in the art.

[0130] In particular, the method of the present invention is advantageous because it has been surprisingly found that specific conditions produce a large quantity of high-quality aviation fuel, see Example 1. The aviation fuel fraction contains C8-C16 hydrocarbons, and in particular, the main portion of the aviation fuel contains C9-C12 hydrocarbons. The aviation fuel fraction can also be characterized by its distillation range, for example, between 150-250°C.

[0131] The first isomerized liquid (119) can be separated into at least one aviation fuel with a cloud point of -25°C or lower, such as -30°C or lower, such as 40°C or lower, such as -47°C or lower.

[0132] Figure 1The process describes feeding an oxygenated hydrocarbon feedstock (104) mixed with hydrogen-rich gas (120) and a hydrocarbon diluent (126) into a first hydrotreating reactor (101) comprising at least one catalytic zone (105) as a product recycling. In a first separation stage (107), the effluent (106) of the first hydrotreating is separated into a first gaseous fraction (121) and a first hydrotreating liquid (108). The first gaseous fraction (121) can be flashed again in a separator at a lower temperature into a fourth gaseous fraction (123), a water-rich fraction (125), and a hydrocarbon-rich fraction (124). The liquid (108) of the first hydrotreated process is mixed with hydrogen-rich gas (120) to form a feed (110) for a second hydrotreated reactor (102) including at least one catalytic zone, wherein hydrodeoxygenation and hydrodenitrification result in a second hydrotreated effluent (130), which is separated in a second separation stage (111) into a second gaseous fraction (113) and a second hydrotreated liquid (112). The second hydrotreated liquid (112) is stripped in a stripping stage (114) with hydrogen-rich gas (120) to form a stripped hydrotreated liquid (115), which is mixed with the hydrogen-rich gas (120) and fed into a first isomerization reactor (103) including at least one catalytic zone, wherein the stripped hydrotreated liquid (115) is isomerized to obtain a first isomerized effluent (116), which is separated in a third separation stage (117) into a third gaseous fraction (118) and the first isomerized liquid (119).

[0133] Figure 2 This refers to the comparative reactor settings mentioned in Comparative Example 1 and Table 7. Compared to... Figure 1 Similar, but the second hydrogenation reactor is omitted. Figure 2The process describes feeding an oxygenated hydrocarbon feedstock A (204) mixed with hydrogen-rich gas A (220) and hydrocarbon diluent A (226) into a first hydrotreating reactor A (201) comprising at least one catalytic zone A (205). In a first separator A (207), the effluent A (206) of the first hydrotreating is separated into a first gaseous fraction A (221) and a first hydrotreating liquid A (208). The first gaseous fraction A (221) can be flashed again at a lower temperature in a second separator A (222) to form a fourth gaseous fraction A (223), a water-rich fraction A (225), and a hydrocarbon-rich fraction A (224). The first hydrotreated liquid A (208) is stripped in a stripping stage A (214) with hydrogen-rich gas A (220) to form stripped hydrotreated liquid A (215), the stripped hydrotreated liquid is mixed with hydrogen-rich gas A (220) and fed into a first isomerization reactor A (203) including at least one catalytic zone, wherein the stripped hydrotreated liquid A (215) is isomerized to obtain a first isomerized effluent A (216), which is separated in a third separator A (217) into a third gaseous fraction A (218) and the first isomerized liquid A (219).

[0134] Figure 3 This is the comparative reactor setup mentioned in Comparative Example 2 and Table 7. It is similar to... Figure 1 However, it does not include the separation step between the first and second hydrogenation reactors. Figure 3An oxygenated hydrocarbon feedstock B (304), mixed with hydrogen-rich gas B (320) and hydrocarbon diluent B (326), is described as being fed in the form of product recycling into a first hydrotreating reactor B (301) comprising at least one catalytic zone B (305). The effluent B (306) of the first hydrotreating is mixed with hydrogen-rich gas B (320) to form a feedstock for a second hydrotreating reactor B (302) comprising at least one catalytic zone, wherein hydrodeoxygenation and hydrodenitrification result in a second hydrotreating effluent B (330), which is separated in a first separator B (307) into a first gaseous fraction B (321) and a second hydrotreating liquid B (312). The first gaseous fraction B (321) may be flashed again in a second separator B (322) at a lower temperature to a fourth gaseous fraction B (323), a water-rich fraction B (325), and a hydrocarbon-rich fraction B (324). The second hydrotreated liquid B (312) is stripped in the stripping stage B (314) with hydrogen-rich gas B (320) to form stripped hydrotreated liquid B (315), the stripped hydrotreated liquid is mixed with hydrogen-rich gas B (320) and fed into a first isomerization reactor B (303) including at least one catalytic zone, wherein the stripped hydrotreated liquid B (315) is isomerized to obtain a first isomerized effluent B (316), which is separated in a third separator B (317) into a third gaseous fraction B (318) and the first isomerized liquid B (319).

[0135] When describing embodiments of the invention, not all possible combinations and arrangements of embodiments are explicitly described. However, the fact that certain measures are stated in mutually different dependent claims or described in different embodiments does not indicate that combinations of these measures cannot be used for advantageous purposes. All possible combinations and arrangements of embodiments are contemplated in this invention.

[0136] The terms “comprising,” “comprise,” and “comprises” used herein are, in each case, intended by the inventors to be optionally replaced by the terms “consisting of,” “consist of,” and “consists of,” respectively.

[0137] Example

[0138] Example 1.

[0139] Low-grade animal fat waste derived from extracts containing beef tallow, lard, and chicken fat is used as feedstock for renewable fuel processing. The feedstock is purified using a bleaching pretreatment before being directed to the hydrotreating process. Table 1 shows the carbon number distribution of the low-grade animal fat feedstock used prior to pretreatment, as measured by GC according to ISO 15304M.

[0140] Table 1. Carbon number distribution of inferior animal fat raw materials before pretreatment by GC analysis.

[0141]

[0142] Table 2. Properties of raw materials before pretreatment

[0143] Table 3. Gel permeation chromatography (GPC) analysis of raw material components before pretreatment.

[0144] Before being used as feedstock for hydrotreating, the feedstock is pretreated by bleaching to reduce the nitrogen content, calculated as total elemental nitrogen, to 1000 w-ppm. This is the nitrogen impurity level of the feedstream entering the hydrotreating process (see entry in Table 4). Nitrogen content in HDO feed (”).

[0145] The feedstocks to be processed by hydrogenation contain nitrogen impurities, inorganic and organic matter. Organic impurities mainly exist in the form of organic nitrogen compounds, such as amides and amines, which are analyzed from the feedstock. The amount of metallic impurities (such as Ca, Co, Fe, Mg, Mn, Ni, and Zn) is less than 1 w-ppm, which is the analytical precision limit of the specific ICP determination used. Similarly, the amount of Al and Na impurities is less than 22 w-ppm, and the P content is less than 1 w-ppm.

[0146] To illustrate the invention with different amounts of nitrogen, the pretreated raw material was mixed with palm oil with a nitrogen content of 18 w-ppm to obtain six different nitrogen concentrations (25, 75, 150, 300, 500, 1000 w-ppm) used in runs 1-6 of this embodiment.

[0147] according to Figure 1 Pretreated feedstocks (fresh feedstocks) containing varying amounts of nitrogen were introduced into a hydrodeoxygenation (HDO) fixed-bed trickle-bed reactor in six separate runs. The HDO reaction was carried out on an alumina support in the presence of a catalyst bed containing 45,000 kg of NiMo sulfide (fresh catalyst exhibiting relative HDO activity compared to fresh HDO catalyst), at a pressure of 50 bar. The feed rate to the HDO reactor was 48,000 kg / h, and the total feed rate (WHSV) was 1.1 h⁻¹. -1The H2 flow rate was approximately 590 Nl H2 / l feed, and the reaction temperature measured at the HDO reactor inlet (TIN) was approximately 309°C, resulting in a high HDO reactor outlet temperature (T). OUT The temperature is approximately 340°C. The fresh hydrogen feed into the reactor is 33,400 m³. 3 / h (NTP), the feed volume of low-quality animal fat waste is 57 m³. 3 / h. Liquid HDO product is recycled as a diluent, with a product recycling ratio of approximately 6:1 to fresh feed.

[0148] The effluent from the HDO reactor is separated into liquid and gas phases in a high-temperature separator before being fed into the refining reactor. The HDO reactor is connected to the refining reactor, as shown below. Figure 1 As shown. The refining reactor is a fixed-bed trickle-bed reactor containing a NiMo sulfide catalyst on the same alumina support as the HDO reactor (the fresh catalyst has relative HDO activity compared to the fresh HDO catalyst), with a catalyst material amount of 15,000 kg. The refining reactor operates at a pressure of 50 bar and a feed rate WHSV of approximately 2.7 h⁻¹. 1 The inlet temperature of the refining reactor (T) IN The temperature is approximately 340°C, which is 31°C higher than the HDO inlet temperature. The amount of hydrogen used is approximately 8 vol% of the amount of hydrogen used in the HDO reactor.

[0149] Table 4 shows the results as follows: Figure 1 The results of the test runs (runs 1-6) of the apparatus shown are as described above, in which the HDO reactor is accompanied downstream by a purification reactor, in which gaseous byproducts containing nitrogen compounds are removed between the two reactors. As shown in Table 4, although the nitrogen content of the fresh feed is very high, the nitrogen content after the purification step can be kept low. Low nitrogen content is desirable in the product for various reasons, especially because low nitrogen content affects the isomerization reaction, thus producing better low-temperature flow properties under the same isomerization conditions compared to products with higher nitrogen content before isomerization (data not shown).

[0150] By altering the processing conditions, particularly increasing the processing temperature in the refining reactor, the nitrogen content can be reduced to less than or equal to 0.4 w-ppm. In all runs (1-6), the final nitrogen impurities were less than or equal to 0.3 w-ppm. Increasing the temperature in the HDO reactor typically leads to uncontrollable reactions, resulting in poor low-temperature properties of the final isomerization product. Following hydrodeoxygenation and refining, the final liquid alkane effluent is hydroisomerized in the isomerization reactor. Isomerization is carried out in a fixed-bed trickle-bed reactor in the presence of a Pt-SAPO catalyst at a pressure of 40 bar for a WHSV of 1.5 h.-1 The reaction temperature was 328°C. The hydrogen to feed ratio was 300 normal liters of H2 per liter of feed.

[0151] The extremely low nitrogen content in all experiments resulted in excellent low-temperature properties of the product. After isomerization and distillation, aviation fuel fractions were obtained with a T10 cutoff temperature of 185 to 205°C, a T90 cutoff temperature of 270 to 295°C, and a final boiling point of 275 to 300°C, conforming to Appendix A2 of ASTM D7566 (2016), and a density of less than 772 kg / m³. 3 (Measured according to ASTM 4052 (2018)), and the freezing point is below -40°C (measured according to IP529). The obtained aviation fuel composition further has a cloud point below -30°C (determined according to ASTM D5771 (2017)) and an excellent yield of approximately 60 wt%.

[0152] Table 4. HDO Reactor and Purification Reactor - Fresh Catalyst - Figure 1

[0153] Comparative Example 1

[0154] Tested according to Figure 2 The reactor device serves as an effective alternative for removing unwanted oxygen and nitrogen impurities. Figure 2 In this apparatus, the same feed composition as in Example 1 was used, and the operating conditions (temperature, pressure, catalyst, etc.) were substantially the same as in Example 1, except that there was no refining reactor downstream of the HDO reactor in this reactor apparatus. Instead, in this example, the entire amount of fresh catalyst (60,000 kg) was used in a single HDO reactor. The HDO reaction was carried out at a pressure of 50 bar, the feed rate of the HDO reactor was 48,000 kg / h, and the total feed rate (WHSV) was 0.8 h. -1 The H2 flow rate is approximately 590 Nl H2 / l feed, and at the HDO reactor inlet (T IN The measured reaction temperature was approximately 308°C, resulting in a temperature (T) at the outlet of the HDO reactor. OUT The process was carried out at approximately 340°C. The fresh hydrogen feed into the reactor was 33,400 m³. 3 / h (NTP), the feed volume of low-quality animal fat waste is 57 m³. 3 / h. Liquid HDO product is recycled as a diluent, with a product recycling ratio of approximately 6:1 to fresh feed.

[0155] Table 5 shows the results. Figure 2The results shown are from operation in a single HDO reactor, including the removal of gaseous nitrogen-containing byproducts after the HDO reaction before they enter the liquid alkane effluent for the isomerization stage.

[0156] As can be seen from Table 5, the nitrogen content before operation (7-12) of all isomerization reactors was higher than that in Example 1. In Comparative Example 1, the same amount of catalyst was used, but now it was done in a single reactor, unlike in Example 1. This comparison shows that a single reactor cannot remove nitrogen in a similar efficient manner to dividing the catalyst volume into two separate reactors and removing the gas phase between them.

[0157] An increase in nitrogen content in the feed inevitably leads to an increase in nitrogen in the final liquid alkane effluent, resulting in poorer low-temperature performance and yield of the aviation fuel components recovered through isomerization and distillation. In Operation 12 with an initial nitrogen content of 1000 ppm, a cloud point of approximately -10°C was obtained, with an aviation fuel yield of 5 wt%.

[0158] Table 5. Single HDO reactor only - Fresh catalyst - Figure 2

[0159] Comparative Example 2

[0160] like Figure 3 The reaction apparatus shown is otherwise similar to that of Example 1, except that it uses two HDO reactors in series and a second hydrotreating reactor B (302) downstream of the first hydrotreating reactor B (301), and there is no gas removal after the first hydrotreating reactor. Similar to Figure 1 The catalyst bed of the refining reactor is installed within the second hydrotreating reactor B (302). The liquid alkane effluent from the first hydrotreating reactor is directly directed to the second hydrotreating reactor, i.e., gaseous byproducts, including nitrogen-containing compounds, are not removed before the liquid alkane effluent enters the second hydrotreating reactor. The final liquid alkane effluent obtained after the second hydrotreating reactor B (302) is directed to the stripping stage B (314) to remove gaseous impurities, and then enters the isomerization reactor. The catalyst and reaction conditions are the same as in Example 1.

[0161] This reactor apparatus is similar to the prior art reactor apparatus described in US 2011 / 0094149 A1.

[0162] As can be seen from Table 6, the nitrogen content of all runs (13-18) was much higher than that in Example 1.

[0163] Discovery based on Figure 3The unit is able to reduce low levels of nitrogen impurities with low initial feed nitrogen content (e.g., about 25 ppm or less). However, when the amount of nitrogen in the fresh feed increases to 150 wtppm or higher, the residual nitrogen after the HDO and refining reactors increases to 0.8 ppm or higher. The increased nitrogen content during isomerization results in poorer cryogenic properties and yields of the aviation fuel components recovered by separation distillation after isomerization; in Operation 18 with an initial nitrogen content of 1000 ppm, the aviation fuel yield was 10 wt%, and the cloud point was about -15°C.

[0164] Table 6 - Two HDO Reactors - Fresh Catalyst - Figure 3

[0165] Example 2 – Aging Catalyst

[0166] During operation, the activity of the catalyst in the HDO catalyst bed tends to decrease, eventually reaching the end of its life cycle, and the catalyst material needs to be replaced.

[0167] Run 20 below shows the results obtained when the HDO catalyst bed was used after a considerable run time (i.e., reaching the run endpoint), at which point the activity of the catalyst bed had decreased to two-thirds of the initial value of the fresh catalyst bed. Comparative Examples 1 and 2 (Runs 19 and 21) were also repeated with aged catalysts of lower activity. The reaction conditions for Runs 19, 20, and 21 were as described in Comparative Examples 1, 20, and 21, respectively, except that the HDO temperature was increased, as described below.

[0168] The performance of the HDO reactor decreases as catalyst activity declines at the end of its operating cycle. This gradual catalyst deactivation can be partially compensated for by increasing the temperature of the HDO catalyst bed. In this embodiment, the HDO reactor (T IN The temperature of the catalyst increased from about 309°C to about 320°C at the end of the catalyst run, an increase of about 11°C.

[0169] As can be seen from the results in Table 7 below, when using a catalyst that has reached the end of its operation, the reactor device according to the present invention still effectively removes nitrogen content.

[0170] Table 7. Using catalyst beds with aging (end of operation) Figure 1 , 2 The different reactor devices shown in Figure 3 are used in... The test run of the line.

[0171]

[0172] Example 3 - Aging catalyst after operation

[0173] Compared with Example 2 (experiment completed), Example 1 ( Figure 1) and Comparative Example 1 ( Figure 2 ) and 2 ( Figure 3 The reactor setup shown in the diagram used an extended time period. The operating cycle was extended until the activity of the HDO reactor catalyst decreased to 60% of its activity compared to fresh HDO catalyst.

[0174] Due to the risk of undesirable products, the gradual degradation of this catalyst bed was no longer compensated for by increasing the temperature of the HDO catalyst bed as in the end-of-run experiment (Table 7). The temperature was maintained at the same value as the end-of-run measurement in Example 2.

[0175] The results in Table 8 regarding nitrogen removal efficiency over extended operating cycles indicate that connecting to a refining bed reactor and removing gaseous byproducts ( Figure 1 The reactor unit using HDO catalysts (including nitrogen-containing compounds) was still able to maintain very low nitrogen impurity levels, less than or equal to 0.3 ppm. In comparison reactor units ( Figure 2 and Figure 3 In the reactor unit with a single HDO catalyst bed and the reactor with two HDO catalyst layers in sequence, the nitrogen residual level began to increase, increasing to 4.5 ppm and 4.2 ppm, respectively.

[0176] Therefore, the results shown in Table 7 indicate that the reactor device according to the invention allows for continuous operation after catalyst deactivation, which is typically characterized at the end of operation.

[0177] Table 8. Test runs using different reactor units over extended periods exceeding the typical end-of-run time. OK.

[0178]

[0179] Increasing the processing temperature in the refining reactor can further reduce the final nitrogen impurity content. However, this does not apply to HDO reactors; increasing the processing temperature in HDO reactors typically leads to uncontrollable reactions and poor low-temperature properties.

[0180] Table 4 shows the usage as follows: Figure 1 The results of the test run (Experiments 1-6) of the apparatus shown are as follows: the apparatus includes an HDO reactor, downstream of which is a purification reactor, both of which have fresh catalyst beds, and gaseous byproducts including nitrogen-containing compounds are removed between the two reactors.

[0181] It is noteworthy that although the nitrogen content in the liquid alkane effluent increases after HDO enters the refining reactor, the final nitrogen content measured in the feed stream of the isomerization reactor remains very low.

Claims

1. A method for preparing hydrocarbons from oxygen-containing hydrocarbon feedstock, wherein the oxygen-containing hydrocarbon feedstock has nitrogen impurities of 300 wppm or higher based on elemental nitrogen, the method comprising: - A first hydrotreating reactor (101) includes at least one catalytic zone (105), wherein a hydrotreating inlet stream containing an oxygenated hydrocarbon feedstock (104) and a hydrocarbon diluent (126) is introduced into the catalytic zone along with a hydrogen-rich gas (120) at an inlet temperature and pressure that at least causes hydrodeoxygenation and hydrodenitrification, such that the effluent (106) of the first hydrotreating from the first hydrotreating reactor mainly contains hydrocarbons, and wherein the oxygenated hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons; - The effluent (106) from the first hydrotreating reactor undergoes a first separation stage (107), wherein at least a portion of the first hydrotreating effluent (106) is separated into a first gaseous fraction (121) and a first hydrotreating liquid (108), wherein the first hydrotreating liquid contains greater than or equal to 95 wt% hydrocarbons and greater than 1 wppm nitrogen; - At the inlet temperature and pressure that cause hydrodeoxygenation and hydrodenitrification, at least a portion of the first hydrotreated liquid (108) and hydrogen-rich gas (120) are introduced into a second hydrotreated reactor (102), the second hydrotreated reactor including at least one catalytic zone, the inlet temperature being higher than the inlet temperature in the first hydrotreated reactor, wherein the first hydrotreated liquid is not mixed with a feed having an oxygen content higher than the oxygen content of the first hydrotreated liquid, and wherein the first hydrotreated liquid is not mixed with a feed having a nitrogen content higher than the nitrogen content of the first hydrotreated liquid; - The effluent (130) from the second hydrotreating reactor (102) undergoes one or more second separation stages (111) and / or stripping stages (114), wherein the effluent (130) is separated into a second gaseous fraction (113) and a second hydrotreating liquid (112) and / or a stripped hydrotreating liquid (115), wherein the second hydrotreating liquid (112) or the stripped hydrotreating liquid (115) contains hydrocarbons greater than or equal to 99 wt% and nitrogen less than or equal to 1 wppm based on elemental nitrogen; The inlet temperature and pressure of the first hydrogenation reactor (101) are 200-400°C and 10-150 bar, respectively. The inlet temperature and pressure of the second hydrogenation reactor (102) are 250-450°C and 10-150 bar, respectively. The degree of hydrodeoxygenation and hydronitrogenation in the first hydrotreatment reactor is controlled in such a way that the temperature rise between the reactor inlet and the reactor outlet in the second hydrotreatment reactor is no more than 10°C.

2. The method according to claim 1, comprising isomerizing the second hydrotreated liquid (112) or the stripped hydrotreated liquid (115) in a first isomerization reactor (103), the first isomerization reactor comprising at least one catalytic zone, wherein the second hydrotreated liquid and a hydrogen-rich gas (120) having nitrogen of less than or equal to 1 ppm mol / mol based on elemental nitrogen are introduced into the catalytic zone at an inlet temperature and pressure that at least causes hydroisomerization to produce a first isomerized effluent (116); - The first isomerization effluent (116) from the first isomerization reactor (103) undergoes a third separation stage (117), wherein the first isomerization effluent (116) is separated into a third gaseous fraction (118) and a first isomerization liquid (119), wherein the first isomerization liquid contains greater than or equal to 30 wt% branched hydrocarbons and / or the branched hydrocarbons are increased by greater than or equal to 30 wt% compared with the liquid of the second hydrotreating.

3. The method according to claim 1, wherein the second hydrogenated liquid (112) or the stripped hydrogenated liquid (115) contains hydrocarbons of greater than or equal to 99 wt% and nitrogen of less than or equal to 0.4 wppm based on elemental nitrogen.

4. The method according to claim 1, wherein the separation stage comprises subjecting the second hydrogenated liquid (112) or the second hydrogenated effluent (130) to a stripping stage (114), wherein the second hydrogenated liquid or the second hydrogenated effluent is stripped with a hydrogen-rich gas (120), such that the stripped hydrogenated liquid (115) has a nitrogen content of less than or equal to 0.4 wppm based on elemental nitrogen; - The stripped hydrotreated liquid (115) is isomerized in a first isomerization reactor (103), the first isomerization reactor comprising at least one catalytic zone, wherein the stripped hydrotreated liquid (115) and a hydrogen-rich gas (120) having nitrogen of less than or equal to 1 ppm mol / mol in elemental nitrogen are introduced into the catalytic zone at a temperature and pressure that at least causes hydroisomerization to produce a first isomerized effluent (116); - The first isomerization effluent (116) from the first isomerization reactor (103) undergoes a third separation stage (117), wherein the first isomerization effluent (116) is separated into a third gaseous fraction (118) and a first isomerization liquid (119), wherein the first isomerization liquid contains greater than or equal to 30 wt% branched hydrocarbons.

5. The method according to claim 2 or 4, wherein the first isomerized liquid (119) is separated into at least one aviation fuel with a cloud point of -40°C or lower.

6. The method according to claim 2 or 4, wherein the first isomerized liquid (119) is separated into at least one aviation fuel with a cloud point of -47°C or lower.

7. The method according to any one of claims 1-4, wherein cooling is applied during the separation phase of the effluent (106) of the first hydrotreating to such an extent that the temperature of the liquid (108) of the first hydrotreating is lower than the inlet temperature of the first catalytic zone of the first hydrotreating reactor.

8. The method according to claim 7, wherein the temperature of the liquid (108) undergoing the first hydrogenation treatment is at least 50°C lower than the inlet temperature of the first catalytic zone of the first hydrogenation treatment reactor.

9. The method according to any one of claims 1-4, wherein the hydrocarbon diluent is not introduced into the second hydrogenation reactor (102).

10. The method according to any one of claims 1-4, wherein the catalytic zone in the first hydrotreatment reactor (101) has a lower hydrodeoxygenation activity than the catalytic zone in the second hydrotreatment reactor (102).

11. The method according to any one of claims 1-4, wherein the hydrogen-rich gas (120) used in the second hydrogenation reactor (102) contains nitrogen impurities of less than or equal to 5 wppm based on elemental nitrogen.

12. The method according to any one of claims 1-4, wherein the inlet temperature and pressure of the first hydrogenation treatment reactor (101) are 250-380°C and 20-120 bar.

13. The method according to any one of claims 1-4, wherein the inlet temperature and pressure of the first hydrogenation treatment reactor (101) are 280-360°C and 30-100 bar.

14. The method according to any one of claims 1-4, wherein the first hydrogenation reactor (101) comprises at least three catalytic zones.

15. The method according to any one of claims 1-4, wherein the catalytic zone of the first hydrogenation reactor comprises one or more catalysts selected from hydride metals on a support.

16. The method of claim 15, wherein the catalyst is selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof.

17. The method of claim 15, wherein the catalytic region comprises one or more catalysts selected from CoMo, NiMo, NiW, and CoNiMo on a support.

18. The method of claim 17, wherein the carrier is alumina.

19. The method according to any one of claims 1-4, wherein the first hydrogenation treatment reactor (101) operates for 0.5-3 h. -1 WHSV within the range; and H2 flow downflow operation with a feed of 350-900 Nl H2 / l.

20. The method according to any one of claims 1-4, wherein the inlet temperature and pressure of the second hydrogenation reactor (102) are 300-430°C and 20-120 bar.

21. The method according to any one of claims 1-4, wherein the inlet temperature and pressure of the second hydrogenation reactor (102) are 330-410°C and 30-100 bar.

22. The method according to any one of claims 1-4, wherein the second hydrogenation reactor (102) has a single catalytic zone.

23. The method according to any one of claims 1-4, wherein the catalytic zone of the second hydrogenation reactor comprises one or more catalysts selected from hydride metals on a support.

24. The method of claim 23, wherein the catalyst is selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof.

25. The method of claim 23, wherein the catalytic region comprises one or more catalysts selected from CoMo, NiMo, NiW, and CoNiMo on a support.

26. The method of claim 25, wherein the carrier is alumina.

27. The method according to any one of claims 1-4, wherein the second hydrogenation reactor (102) is in operation for 0.5-3 h. -1 WHSV within the range; and H2 flow downflow operation with a feed of 350-900 Nl H2 / l.

28. The method according to claim 2 or 4, wherein the inlet temperature and pressure of the first isomerization reactor (103) are 280-370°C and 20-50 bar.

29. The method according to claim 2 or 4, wherein the catalytic zone of the first isomerization reactor comprises one or more catalysts, the catalysts comprising a Group VIII metal on a support, wherein the support is selected from silica, alumina, clay, titanium dioxide, boron oxide, zirconium oxide, which may be used alone or as a mixture.

30. The method of claim 29, wherein the carrier is silicon dioxide and / or aluminum oxide.

31. The method of claim 18, wherein the one or more catalysts further comprise molecular sieves.

32. The method of claim 31, wherein the molecular sieve is a zeolite.

33. The method according to claim 2 or 4, wherein the first isomerization reactor (103) is in operation for 0.5-1 h. -1 WHSV within the range; and H2 flow downflow operation with 300-500 Nl H2 / l feed.

34. The method according to claim 2 or 4, wherein the ratio of isoalkane to n-alkane in the first isomerized liquid is greater than 1.

35. The method according to claim 2 or 4, wherein the ratio of isoalkane to n-alkane in the first isomerized liquid is 1 to 2.

5.

36. The method according to any one of claims 1-4, wherein the hydrogenation treatment inlet stream has 100 to 500 wppm of nitrogen impurities.

37. The method according to any one of claims 1-4, wherein the effluent (106) of the first hydrotreating from the first hydrotreating reactor has 100 to 500 wppm or higher nitrogen impurities.

38. The method according to any one of claims 1-4, wherein the second hydrogenated liquid (112) and / or the stripped hydrogenated liquid (115) contain hydrocarbons of greater than or equal to 99 wt% and nitrogen of less than or equal to 0.3 wppm based on elemental nitrogen.

39. The method according to any one of claims 1-4, wherein the hydrocarbon diluent (126) is a product recycling product.

40. The method according to any one of claims 1-4, wherein the oxygenated hydrocarbon feedstock contains 25 wt% or more of fatty acids or fatty acid esters.

41. The method according to any one of claims 1-4, wherein the oxygenated hydrocarbon feedstock is selected from vegetable oils and animal fats.

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