Method for producing renewable fuels

Abstract

This application describes a process for making hydrocarbons from an oxygenate-containing hydrocarbon feedstock having high nitrogen impurities, such as animal fats. The process includes hydroprocessing of the oxygenate-containing feedstock in a first hydroprocessing bed disposed downstream of a finishing bed. After the first hydroprocessing bed, the gas phase is removed and the liquid hydroprocessing phase is fed to the finishing bed, disposed upstream of the first hydroprocessing bed, along with fresh hydrogen, which further reduces any nitrogen impurities contained in the finished hydrocarbon product. This particular process arrangement effectively removes nitrogen impurities from the resulting hydrocarbon product, resulting in an improved cloud point after isomerization, and at the same time this particular arrangement enables the efficient use of fresh hydrogen for finishing, thereby providing a finished hydrocarbon product rich in dissolved hydrogen, where a portion of the product can be used as a hydrocarbon diluent in downstream hydroprocessing beds, and / or can be withdrawn between the finishing bed and the hydroprocessing bed and isomerized in an isomerization reactor.

Description

Technical Field

[0001] This invention relates to a method for preparing hydrocarbons from oxygen-containing hydrocarbon feedstocks containing nitrogen impurities, and more particularly to the efficient utilization of hydrogen in such methods. Background Technology

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

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

[0004] Hydrotreating of fossil and renewable oils uses excess hydrogen compared to theoretical consumption. The hydrogen remaining after the hydrotreating step can be purified and recycled, along with other fresh hydrogen, to compensate for the hydrogen consumed in the hydrotreating process; this is known as compensating hydrogen.

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

[0006] Hydroisomerization is typically carried out on bifunctional catalysts possessing both metal dehydrogenation and acidic functions, such as platinum or palladium catalysts and molecular sieves like SAPO-11. If a reduction in the average molecular weight of the feed is not desired during hydrotreatment, the isomerization selectivity of the catalyst is important, i.e., suppressing hydrocracking, which typically occurs to some extent during hydroisomerization. This involves a balance between the metal dehydrogenation and acidic functions, which is sensitive to elements that can alter this balance. Amines are presumably used to neutralize strong acid sites, resulting in low 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 oils from fossil and renewable sources, as well as animal waste fats. The average nitrogen impurity content in crude oil has been reported to be 940 w-ppm, with some reaching as high as 7500 w-ppm (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). Animal waste fats can commonly contain 1000 ppm of nitrogen or even higher. A typical approach to treating undesirable impurities in feedstocks, such as nitrogen impurities, is to purify the feedstock prior to hydrotreating. Removal of water-soluble nitrogen compounds is typically achieved through degumming. However, in animal fats, most nitrogen compounds are oil-soluble and significantly more difficult to remove than water-soluble nitrogen compounds.

[0008] US 2011 / 0094149 A1 (granted by 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 gas and liquid effluent from the bed, whose outlet temperature is higher than the inlet temperature, is directly used as recirculation to heat the fresh feed entering the catalytic zone. US 2011 / 0094149A1 illustrates the invention using high-quality palm oil and soybean oil, which have low nitrogen impurities of 15 and 23 ppm, respectively, and mentions that feed from renewable sources typically contains a variety of impurities, such as nitrogen impurities typically ranging from 1-100 ppm, and even up to 1 wt%.

[0009] US 2011 / 0094149 A1 reduces the amount of nitrogen in the examples to about 2% of the original amount and does not hydrogenate any impure feedstock with a nitrogen content outside the general range of 1-100 ppm. Under the operating conditions described in US 2011 / 0094149 A1, Comparative Example 1 hydrogenates and isomerizes animal fat with a nitrogen content of about 1 wt%, demonstrating the possibility of hydrogenating impure feedstocks with a nitrogen content outside the general range of 1-100 ppm. However, the nitrogen content after the hydrodeoxygenation stage is about 2-5 ppm, and after isomerization, the yield of the high-pour-point aviation fuel cut with a temperature of -10°C is only 5%, compared to aviation fuel requirements.

[0010] Therefore, there remains a need for other hydrotreating methods that can effectively hydrotreat oxygenated hydrocarbons with nitrogen impurities outside the general range of 1-100 ppm and ensure low nitrogen content in the hydrotreating products. Additionally, there remains a need for methods to produce high-quality aviation fuel fractions with excellent cold-flow properties from oxygenated hydrocarbons with nitrogen impurities outside the general range of 1-100 ppm.

[0011] 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 very difficult to remove.

[0012] In addition, excess hydrogen that is added and usually recycled needs to be utilized more efficiently. Summary of the Invention

[0013] This invention is made in view of the above-mentioned prior art, and the object of this invention is to provide a method that can improve the quality of hydrotreated products obtained from oxygenated hydrocarbon feed containing nitrogen impurities, while simultaneously enabling more efficient hydrogen utilization. Specifically, the improved quality includes at least a small amount of nitrogen impurities in the product and improved cold flow properties of the isomerization products.

[0014] To address this problem, the present invention provides a method for preparing hydrocarbons from an oxygen-containing hydrocarbon feedstock having nitrogen impurities of 10 w ppm or higher based on elemental nitrogen. The method includes a reactor (101) comprising a first catalytic zone / refining zone (102) arranged upstream of a second catalytic zone / hydrogenation zone (105). The oxygen-containing hydrocarbon feedstock is fed into the hydrogenation zone, and the effluent from the first hydrogenation zone is purified. The purified effluent from the first hydrogenation zone (108) is hydrogenated at high temperature in the refining zone (102), and the feed to the refining zone (102) is not mixed with the oxygen-containing hydrocarbon feedstock, i.e., not mixed with fresh feed.

[0015] Specifically, the present invention relates to a method for preparing hydrocarbons from oxygen-containing hydrocarbon feedstock having nitrogen impurities of 10 wppm or higher based on elemental nitrogen, comprising:

[0016] - A hydrotreating reactor (101) comprising a first catalytic zone (102) arranged above a second catalytic zone (105), wherein a hydrotreating inlet stream comprising an oxygenated hydrocarbon feedstock (104), a hydrogen-rich gas (120), and optionally a product recycling diluent (108, 126) is introduced into the second catalytic zone (105) through an inlet located between the first (102) and the second catalytic zone (105), where it is mixed with a portion of a first hydrotreating effluent from the first catalytic zone, wherein the second catalytic zone is operated at temperatures and pressures that cause at least hydrodeoxygenation and hydrodenitrification to such an extent that a second hydrotreating effluent (106) from the second catalytic zone (105) of the hydrotreating reactor comprises primarily hydrocarbons, and wherein the oxygenated hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons;

[0017] - The second hydrotreating effluent from the second catalytic zone of the hydrotreating reactor undergoes a separation stage (107), wherein at least a portion of the second hydrotreating effluent (106) is separated into a gaseous fraction (121) and a hydrotreating liquid (108), wherein the hydrotreating liquid contains greater than or equal to 95 wt% hydrocarbons and greater than 1 w ppm nitrogen.

[0018] - At the inlet temperature and pressure that cause hydrodeoxygenation and hydrodenitrification, at least a portion of the hydrotreatment liquid (108) and hydrogen-rich gas (120) are introduced into the first catalytic zone (102) of the hydrotreatment reactor (101), the inlet temperature of which is higher than the inlet temperature in the second catalytic zone of the hydrotreatment reactor;

[0019] - A product side stream (112) containing a portion of the first hydrotreating effluent from the first catalytic zone (102) is taken out between the first and second catalytic zones. The product side stream (112) contains a liquid component and a gaseous component, and wherein the liquid component of the side stream contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 w ppm nitrogen as elemental nitrogen, preferably less than or equal to 0.4 w ppm nitrogen, such as less than or equal to 0.3 w ppm nitrogen (tested by ASTM D4629).

[0020] In other words, in a first aspect of the invention, the inventors have discovered that when ammonia and other low-boiling-point amines are removed from the effluent from the second catalytic zone (105) (hydrotreating zone) by separating the liquid phase into a gas phase and a liquid phase, and then hydrogenating the resulting liquid phase in the first catalytic zone (102) (purification zone), oxygenated hydrocarbons containing nitrogen impurities can be effectively hydrogenated in both catalytic zones within the reactor, wherein such liquid phase is neither mixed with other oxygenated hydrocarbon feeds nor with other feeds having a nitrogen content higher than that of the first hydrogenated liquid. At least a portion of the first hydrogenated effluent is taken out as a side stream and separated into a gas stream and a second hydrogenated liquid stream. The separation may be a stripping step or a subsequent stripping step (114), wherein the first hydrogenated liquid stream may be stripped with a stripping gas, such as hydrogen, to reduce the nitrogen content of the stripped side stream (115) to 0.3 wppm or lower.

[0021] Specifically, the inventors have discovered that ammonia, which is formed from nitrogen impurities in the feed during hydrotreating and is present in hydrogen-rich exhaust gas, can be reincorporated into the product under deeper hydrodeoxygenation / hydrodenitrification conditions if the hydrogen-rich gas containing these ammonia impurities is used in a purification step without prior removal of the ammonia impurities.

[0022] By using a refining zone (first catalytic zone) upstream of the hydrotreating zone (second catalytic zone), fresh hydrogen can be utilized better compared to a reactor with a refining zone downstream of the hydrotreating zone. This is because the feed to the first catalytic zone (102) (refining zone) already contains less nitrogen than the oxygen-containing hydrocarbon feed to the second catalytic zone (105) (hydrotreating zone), and the fresh hydrogen added to the refining zone will not contain nitrogen impurities present in the effluent from the second catalytic zone. Furthermore, the excess hydrogen present in the effluent from the first catalytic zone (102) (refining zone) still has a suitable quality for use in the second catalytic zone (105) (hydrotreating zone).

[0023] The reactor apparatus and method of the present invention result in more efficient hydrogen use while ensuring a low amount of nitrogen impurities in the product side stream (112).

[0024] The product side stream (112) can be used as the product itself or it can be isomerized in an isomerization reactor (103) containing at least one catalytic zone, wherein the product side stream (112) and hydrogen-rich gas (120) are introduced into the catalytic zone at an inlet temperature and pressure that causes at least hydroisomerization to produce an isomerized effluent (116), the hydrogen-rich gas may contain less than or equal to 1 ppm (mol / mol) of nitrogen as elemental nitrogen;

[0025] - The isomerization effluent from the isomerization reactor undergoes a separation stage (117), in which the isomerization effluent (116) is separated into a gaseous fraction (118) and an isomerization liquid (119), wherein the isomerization liquid contains greater than or equal to 30 wt% branched hydrocarbons and / or the increase in branched hydrocarbons is greater than or equal to 30 wt% compared with the product side stream (112).

[0026] For example, the side stream can undergo a stripping stage (114), in which the side stream (116) is stripped with stripping gas (H2), resulting in the stripping side stream (115) having less than or equal to 0.4 wppm of nitrogen as elemental nitrogen, such as less than or equal to 0.3 wppm of nitrogen (as measured by ASTM D4629), and a lower amount of nitrogen compared to the side stream (116); the step of isomerizing the stripping side stream (115) can be carried out in an isomerization reactor (103) containing at least one catalytic zone, wherein the stripping side stream (115) having less than or equal to 1 ppm (mol / mol) of nitrogen as elemental nitrogen and hydrogen-rich gas (120) are introduced into the catalytic zone at a temperature and pressure that causes at least hydroisomerization to produce the first isomerized effluent (116);

[0027] The isomerization effluent from the isomerization reactor (103) undergoes a separation stage, in which the isomerization effluent is separated into a gaseous fraction and an isomerized liquid, 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 stripping side stream (115).

[0028] The isomerized liquid can be separated into aviation fuels with a freezing point of at least -40°C or lower, such as -47°C or lower.

[0029] Cooling can be applied during the separation phase of the second hydrotreating effluent (106) to achieve a temperature in the second hydrotreating liquid (108) that is lower than the inlet temperature of the first catalytic zone (102) of the first hydrotreating reactor (101).

[0030] Hydrocarbon diluents and fresh oxygenated hydrocarbon feedstocks are not intended to be introduced into the first catalytic zone of the hydrotreating reactor (102).

[0031] The degree of hydrodeoxygenation and hydronitrogenation in the second catalytic zone (105) can be controlled in such a way that the temperature rise between the inlet and outlet of the first catalytic zone (102) does not exceed 10°C.

[0032] The second catalytic zone (105) in the hydrotreatment reactor (101) may have a lower hydrodeoxygenation activity than the first catalytic zone (102) in the hydrotreatment reactor (101).

[0033] The hydrogen-rich gas (120) used in the first catalytic zone (102) may contain nitrogen impurities of less than or equal to 5 w ppm in terms of elemental nitrogen.

[0034] The inlet temperature and pressure of the second catalytic zone (105) 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.

[0035] The second catalytic zone of the hydrotreating reactor may contain one or more catalysts selected from supported hydrides, such as those selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. Preferably, the second catalytic zone contains one or more catalysts supported on a support, such as an alumina support, selected from CoMo, NiMo, NiW, and CoNiMo.

[0036] The hydrogenation reactor (101) can operate at a rate of 0.5-3 hours. -1 Operating within the range of WHSV and H2 flow rate of 350-900 Nl H2 / l feed.

[0037] The inlet temperature and pressure of the first catalytic zone (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.

[0038] The first catalytic zone of the hydrotreating reactor contains one or more catalysts, which may be selected from hydride metal compounds supported on a support, such as catalysts selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W or any combination thereof. Preferably, the first catalytic zone contains one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo on a support, such as an alumina support.

[0039] The inlet temperature and pressure of the isomerization reactor (103) can be 280-370 °C and 20-50 bar.

[0040] The catalytic zone of the isomerization reactor contains one or more catalysts, which may be contained in a Group VIII metal on a support, wherein the support is selected from silica, alumina, clay, titanium oxide, boron oxide, zirconium oxide, and may be used alone or as a mixture, preferably silica and / or alumina.

[0041] The catalytic zone of the isomerization reactor may also contain molecular sieves, such as zeolites.

[0042] The isomerization reactor (103) can operate at a rate of 0.5-1 h. -1 Operating within the range of WHSV and H2 flow rate of 300-500 Nl H2 / l feed.

[0043] Isomerized liquids can have a ratio of isoalkanes to n-alkanes greater than 1, such as 5 to 30 or 15 to 30.

[0044] A portion of the first hydrotreating effluent from the first catalytic zone (102) can be used to heat the hydrotreating inlet stream, for example, by mixing and heating.

[0045] The oxygenated hydrocarbon feedstock may have nitrogen impurities of 300 wppm or higher, preferably 500 wppm or higher, based on elemental nitrogen.

[0046] The inlet stream of the hydrotreating process can have nitrogen impurities ranging from 100 to 500 wppm.

[0047] The second hydrotreating effluent (106) from the second catalytic zone may have 100 to 500 wppm or higher nitrogen impurities. Attached Figure Description

[0048] Figure 1 The process scheme shown is that the hydrotreating reactor (101) includes a first catalytic zone (102) (purification bed) and a first isomerization reactor (103) arranged above the second catalytic zone (105) (hydrotreating bed).

[0049] Figure 2 A comparative process scheme not according to the invention is shown, which has a first hydrogenation reactor (201) and a first isomerization reactor (203).

[0050] Figure 3 A comparative process scheme not according to the invention is shown, which has a first hydrogenation reactor (301), a second hydrogenation reactor (302) and a first isomerization reactor (303). Detailed Implementation

[0051] In describing embodiments of the invention, specific terminology will be used for clarity. However, the invention is not intended to be 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.

[0052] This invention relates to a method for preparing hydrocarbons from oxygenated hydrocarbon feedstocks having nitrogen impurities of 10 wppm or higher based on elemental nitrogen, comprising:

[0053] - A hydrotreating reactor (101) comprising a first catalytic zone (102) arranged above a second catalytic zone (105), wherein a hydrotreating inlet stream comprising an oxygenated hydrocarbon feedstock (104), a hydrogen-rich gas (120), and optionally a product recycling diluent (108, 126) is introduced into the second catalytic zone (105) through an inlet located between the first (102) and the second catalytic zone (105), where it is mixed with a portion of a first hydrotreating effluent from the first catalytic zone, wherein the second catalytic zone is operated at temperatures and pressures that cause at least hydrodeoxygenation and hydrodenitrification to such an extent that a second hydrotreating effluent (106) from the second catalytic zone (105) of the hydrotreating reactor comprises primarily hydrocarbons, and wherein the oxygenated hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons;

[0054] - The second hydrotreating effluent from the second catalytic zone of the hydrotreating reactor undergoes a separation stage (107), wherein at least a portion of the second hydrotreating effluent (106) is separated into a gaseous fraction (121) and a hydrotreating liquid (108), wherein the hydrotreating liquid contains greater than or equal to 95 wt% hydrocarbons and greater than 1 w ppm nitrogen.

[0055] - At the inlet temperature and pressure that cause hydrodeoxygenation and hydrodenitrification, at least a portion of the hydrotreatment liquid (108) and hydrogen-rich gas (120) are introduced into the first catalytic zone (102) in the hydrotreatment reactor (101), the inlet temperature of which is higher than the inlet temperature in the second catalytic zone of the hydrotreatment reactor.

[0056] - A product side stream (112) containing a portion of the first hydrotreating effluent from the first catalytic zone (102) is taken out between the first and second catalytic zones. The product side stream (112) contains a liquid component and a gaseous component, wherein the liquid component of the side stream contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 w ppm nitrogen as elemental nitrogen, preferably less than or equal to 0.4 w ppm nitrogen, such as less than or equal to 0.3 w ppm nitrogen (tested by ASTM D4629).

[0057] In other words, in a first aspect of the invention, the inventors have discovered that when ammonia and other low-boiling-point amines are removed from the effluent from the second catalytic zone (105) (hydrotreating zone) by separating the liquid phase into a gas phase and a liquid phase, and then hydrogenating the resulting liquid phase in the first catalytic zone (102) (purification zone), oxygenated hydrocarbons containing nitrogen impurities can be effectively hydrogenated in both catalytic zones within the reactor, wherein such liquid phase is neither mixed with other oxygenated hydrocarbon feeds nor with other feeds having a higher nitrogen content than the first hydrogenated liquid. At least a portion of the first hydrogenated effluent is taken out as a product side stream (112) and separated into a gas stream and a second hydrogenated liquid stream. The separation may be a stripping step or a subsequent stripping step (114), wherein the first hydrogenated liquid stream may be stripped with a stripping gas, such as hydrogen, to reduce the nitrogen content of the stripping side stream (115) to 0.4 wppm or less, such as less than or equal to 0.3 wppm of nitrogen (as measured by ASTM D4629).

[0058] Specifically, the inventors have discovered that gaseous ammonia present in hydrogen-rich exhaust gas, formed from nitrogen impurities in the feed during hydrotreating, can be reincorporated into the product under deeper hydrodeoxygenation / hydrodenitrification conditions if the hydrogen-rich gas containing these ammonia impurities is used in a purification step without prior removal of the ammonia impurities.

[0059] By using a refining zone (first catalytic zone) upstream of the hydrotreating zone (second catalytic zone), fresh hydrogen can be utilized better compared to a reactor with a refining zone downstream of the hydrotreating zone. This is because the feed to the first catalytic zone (102) (refining zone) already contains less nitrogen than the oxygen-containing hydrocarbon feed to the second catalytic zone (105) (hydrotreating zone), and the fresh hydrogen added to the refining zone will not contain nitrogen impurities present in the effluent from the second catalytic zone. Furthermore, the excess hydrogen present in the effluent from the first catalytic zone (102) (refining zone) still has a suitable quality for use in the second catalytic zone (105) (hydrotreating zone).

[0060] The reactor apparatus and method of the present invention result in more efficient hydrogen use while ensuring a low amount of nitrogen impurities in the product side stream (112).

[0061] 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 method. Most of these vegetable oils and animal fats consist of 25 wt% or 40 wt% or more of fatty acids as free fatty acids or as free fatty acid esters. Examples of free fatty acid esters are fatty acid glycerides (monoglycerides, diglycerides, and / or triglycerides) or, for example, fatty acid methyl esters (FAME) or fatty acid ethyl esters (FAEE). Therefore, renewable sources of oxygenated hydrocarbon feedstocks can contain 40 wt% or more of fatty acids or fatty acid esters.

[0062] By comparing the raw materials 14 C-isotope content and atmospheric concentrations in 1950 14 C-isotope content is used to determine the renewable characteristics of carbon-containing compositions, such as the raw materials and products. 14 C-isotope content can be used as evidence of a renewable source of raw materials or products.

[0063] Compared to carbon atoms from fossil sources, carbon atoms in renewable materials contain a higher number of unstable radioactive carbon atoms. 14 C) Atoms. Therefore, it is possible to analyze 12 C and 14 Carbon isotope ratios are used to distinguish carbon compounds from biologically derived carbon compounds from fossil-derived carbon compounds. Therefore, a specific ratio of isotopes can be used to identify renewable carbon compounds and distinguish them from non-renewable ones, i.e., fossil carbon compounds. The isotope ratio does not change during chemical reactions. An example of a suitable method for analyzing carbon content from 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 Dijs et al., Radiocarbon, 48(3), 2006, pp. 315-323. For the purposes of this invention, carbon-containing materials, such as feedstocks or products, are considered to be of renewable origin if they contain 90% or more modern carbon, such as 100% modern carbon, as measured using ASTM D6866.

[0064] Some vegetable oils and animal fats may contain typical amounts of nitrogen impurities, such as between 1 and 100 ppm, which can 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 10 wppm or higher. For example, 300 wppm to 2500 wppm or higher, such as 500 wppm or higher, for example, 800 wppm or higher. Oxygenated hydrocarbon feedstocks may, for example, have nitrogen impurities of up to 1500 wppm, such as up to 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 blended 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.

[0065] 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 is more suitable for values ​​above 100 wppm. Both methods can be used as needed in this invention to measure nitrogen impurities as elemental nitrogen.

[0066] The method uses a hydrotreating reactor (101) comprising a first catalytic zone (102) arranged above a second catalytic zone (105), and the method includes allowing a hydrotreating inlet stream to flow into the second catalytic zone (105) through an inlet between the first (102) and the second catalytic zone (105). The hydrotreating inlet stream contains an oxygenated hydrocarbon feedstock (104), which can be selected as described above, for example, vegetable oils, animal fats, or mixtures thereof containing 10 w ppm nitrogen or higher, such as 300 w ppm nitrogen or higher, for example, between 500 and 1500 w ppm nitrogen.

[0067] The oxygen-containing hydrocarbon feedstock is mixed with a portion of the first hydrotreating effluent from the first catalytic zone and optionally a product recycling diluent (108, 126). Using a portion of the first hydrotreating effluent from the first catalytic zone as a hydrocarbon diluent is advantageous from the perspective that it contains hydrocarbons with dissolved hydrogen, resulting in more efficient hydrodeoxygenation (HDO) and hydrodenitrification (HDN) in the second catalytic zone. Using the product recycling (108, 126) as a hydrocarbon diluent is advantageous compared to using the first hydrotreating effluent as a hydrocarbon diluent, where a larger volume of the first hydrotreating effluent product can be discharged as a product side stream (112).

[0068] Hydrocarbon diluents are well known in the art and are used to control the exothermic properties of hydrotreating reactions (e.g., HDO and HDN reactions). Additionally, hydrocarbon diluents may contain dissolved hydrogen, which is necessary for efficient hydrotreating because the catalyst must come into contact with both the oxygen-containing hydrocarbon feedstock and the hydrogen for the hydrotreating reaction to proceed.

[0069] A portion of the first hydrogenation treatment effluent from the first catalytic zone is used ( Figure 1 ,l) is advantageous as a hydrocarbon diluent because it will already contain dissolved hydrogen and it has a high temperature that can be used to heat the inlet of the second catalytic zone (105).

[0070] The portion containing dissolved hydrogen is recycled and mixed with the product from the upstream section, while the effluent is treated with only the first hydrogenation treatment. Figure 1 Compared to using a hydrocarbon diluent, this increases the amount of product sidestream (112) that can be discharged, thereby improving the reactor's production capacity. The first hydrogenation treatment effluent from the first catalytic zone is used as a hydrocarbon diluent. Figure 1 A mixture of both, for example, at least 10% of both, is advantageous, consisting of the product from the second catalytic zone (108, 126) and the product from the second catalytic zone (108, 126).

[0071] A portion of the first hydrotreating effluent from the first catalytic zone (102) can also be used to heat the hydrotreating inlet stream, for example, by mixing and heating.

[0072] As mentioned, the hydrocarbon diluent can be product recycled (108, 126) or hydrocarbons from fossil or renewable sources. It will typically be product recycled and / or the first hydrotreating effluent from the first catalytic zone. The hydrocarbon diluent is typically added in an amount ranging from 1:1 to 4:1 (total hydrocarbon diluent: total oxidized feedstock). As mentioned, the hydrocarbon diluent can be from fossil or renewable sources. Some fossil-derived hydrocarbon feedstocks may contain significant nitrogen impurities. These fossil-derived hydrocarbon feedstocks may also be used alone or mixed with other hydrocarbon diluents, such as product recycled and / or the first hydrotreating effluent from the first catalytic zone, as part of the hydrocarbon diluent. For example, the hydrocarbon diluent can be a mixture of product recycled and fossil hydrocarbons.

[0073] The use of product recycling and the first hydrotreatment effluent from the first catalytic zone is advantageous because they will typically contain dissolved hydrogen, which is relevant to the hydrotreatment reaction depending on the amount of hydrogen dissolved in the liquid phase.

[0074] The hydrotreating inlet stream may have 100 W ppm or higher, for example, 100 to 500 W ppm of nitrogen impurities, and / or the second hydrotreating effluent (106) from the second catalytic zone may have 100 W ppm or higher, for example, 100 to 500 W ppm or higher of nitrogen impurities. The method of the present invention is advantageous from the perspective that the hydrotreating process can convert oxygenated hydrocarbon feedstocks with high nitrogen impurities without extensive dilution to reduce the overall nitrogen impurities in the hydrotreating inlet stream. This is advantageous because extensive dilution would reduce the production capacity of the oxygenated hydrocarbon feedstock in the hydrotreating process. Alternatively, or additionally, the nitrogen content in the second hydrotreating effluent (106) from the second catalytic zone may also be measured, which may have 100 W ppm or higher, for example, from 100 to 500 W ppm or higher of nitrogen impurities.

[0075] Regarding the maximum amount of nitrogen impurities that can exist, there are limitations on the amount of nitrogen impurities present as impurities or the amount of impurities that can be effectively removed. Therefore, the hydrotreatment inlet stream and / or the second hydrotreatment effluent (106) from the second catalytic zone can have up to 500 Wppm or less of nitrogen impurities, i.e., the hydrotreatment inlet stream and / or the second hydrotreatment effluent (106) from the first hydrotreatment reactor can have nitrogen impurities between 100 and 500 Wppm.

[0076] The hydrogenation inlet stream, together with hydrogen-rich gas (120), is introduced into the hydrogenation reactor (101) which contains a first catalytic zone (102) arranged above a second catalytic zone (105).

[0077] Hydrogen-rich gas (120) is necessary for implementation in the first and second catalytic zones (102, 105) of the hydrotreatment reactor (101), particularly for hydrodeoxygenation (HDO) and hydrodenitrification (HDN) reactions. The hydrogen-rich gas can be, for example, excess hydrogen from methods (123, 118) that has been purified by one or more purification steps (122), such as separation (122) into a gaseous fraction (123) containing hydrogen, water, ammonia, and other light substances, followed by ammonia purification and / or membrane separation purification. The purity of the hydrogen-rich gas used in the second catalytic zone is less important than that used in the first catalytic zone (102), for stripping before the isomerization reactor (114), and in the isomerization reactor (103), and it suitably contains no reactive nitrogen, such as ammonia, such as nitrogen less than 0.3 w-ppm as elemental nitrogen. Typically, a hydrogen-rich gas with a purity of 95 mol% or higher is acceptable for use in the second catalytic zone, but it is also possible for it to have a hydrogen purity of less than 95 mol%. Compensating hydrogen can also be mixed to form a hydrogen-rich gas, or the hydrogen-rich gas can consist entirely of the compensating gas.

[0078] The hydrotreating reactor (101) is a vessel capable of housing at least two catalytic zones (102, 105). In this invention, a trickle bed reactor is well-suited. 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.

[0079] The hydrotreating reactor (101) includes a first catalytic zone (102) arranged above a second catalytic zone (105). The catalytic zone can be in its simplest form as a fixed bed of catalyst particles. The catalytic zone can contain a single fixed bed or multiple fixed beds having the same or different catalyst particles, or it can be a layer of catalyst particles with different activities and / or compositions.

[0080] The first catalytic zone (102) may be a single fixed bed, and / or the second catalytic zone (105) may contain at least three fixed beds.

[0081] The hydrogenation inlet stream, together with the hydrogen-rich gas (120), is introduced into the second catalytic zone (105) through an inlet between the first (102) and the second catalytic zone (105).

[0082] The hydrotreatment inlet stream, together with hydrogen-rich gas (120), is introduced into the second catalytic zone at inlet temperatures and pressures that result in the second hydrotreatment effluent (106) from the second catalytic zone (105) of the hydrotreatment reactor being predominantly hydrocarbon-containing, for hydrodeoxygenation and hydronitrogenation.

[0083] There are various combinations of inlet temperatures and pressures that will enable HDO and HDN to remove oxygen from oxygenated hydrocarbons, thereby producing water as a byproduct, and to remove nitrogen impurities from oxygenated hydrocarbons, thereby producing ammonia as a byproduct, thereby obtaining products that are primarily hydrocarbon-containing.

[0084] For example, the inlet temperature and pressure of the second catalytic zone (105) 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.

[0085] Choosing different combinations of temperature and pressure to achieve at least hydrodeoxygenation and hydrodenitrogenation, wherein the second hydrotreatment effluent (106) from the second catalytic zone contains primarily hydrocarbons (where oxygenated hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons, appropriately greater than or equal to 98% hydrocarbons, wherein less than or equal to 2% oxygenated hydrocarbon feedstock is present), is routine work for technicians.

[0086] In the same way that technicians can select different combinations of temperature and pressure, technicians will also be able to select one or more catalysts suitable for the second catalytic zone (105).

[0087] For example, the second catalytic zone of the 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. Preferably, the second catalytic zone is contained on a support, such as an alumina support, one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo.

[0088] The hydrogenation reactor (101) can operate at a rate of 0.5-3 hours. -1 Operating within the range of WHSV and H2 flow rate of 350-900 Nl H2 / l feed.

[0089] More general reaction conditions in the second catalytic zone (105) may include a trickle bed reactor as a hydrotreating reactor (101), which includes a second catalytic zone containing a supported molybdenum-containing hydrogenation catalyst, wherein hydrotreating is carried out in the presence of hydrogen at a temperature of 200-400°C and a pressure between 10-150 bar, wherein the WHSV is 0.5-3 h. -1 Within the range of 300-2100 Nl H2 / l feed H2 flow rate.

[0090] The second catalytic zone will produce a second hydrotreating effluent (106), which will contain a gaseous component in excess of hydrogen, water vapor from HDO, CO and CO2 from the decarboxylation / decarbonylation of carboxylic acids in the oxygenated hydrocarbon feed, and H2S. Finally, NH3 will be produced from the HDN reaction. More ammonia (NH3) will be produced in a process where the oxygenated hydrocarbon feedstock contains 30 wppm or higher nitrogen impurities, compared to the hydrotreating of a normal feedstock, such as palm oil (e.g., which may have 23 ppm nitrogen), which typically contains 1-100 ppm nitrogen. The inventors unexpectedly discovered that, particularly when the hydrotreating effluent is further hydrotreated with added compensating hydrogen, the increased amount of ammonia in the hydrotreating effluent from an oxygenated hydrocarbon feedstock containing 300-wppm or higher nitrogen impurities causes a re-incorporation of nitrogen. In other words, the inventors observed that even after hydrogen stripping, the further hydrotreating effluent from other hydrotreating steps contained 2-5 ppm of nitrogen. That is, even if nitrogen removal was expected to be as complete as possible before contact with the isomerization catalyst, it was simply impossible to reduce the nitrogen content below 2-5 ppm, even after stripping. This was quite unexpected, because by specifically anticipating deeper HDO and HDN hydrotreating, and implementing additional hydrotreating steps at high temperatures, oxygen and nitrogen were removed more thoroughly from the second hydrotreating effluent. Furthermore, it was expected that any reaction of the formed hydrocarbons with ammonia should be inert, and that even under the conditions of other hydrotreating steps, ammonia should react to produce amines or amides, and even if there was a theoretical possibility of forming these nitrogen compounds, these formed compounds would again undergo hydrodenitrification (HDN) to remove ammonia. However, it was unexpectedly discovered that nitrogen compounds that did not disappear again under the hydrotreating conditions in other hydrotreating steps were produced. These compounds included secondary and tertiary amides.

[0091] As is known in the art, nitrogen can deactivate isomerization catalysts, which is why ammonia contained in the effluent to be fed into the isomerization reactor is typically stripped with stripping gas, thereby removing any remaining amount of nitrogen by replacing / stripping any dissolved ammonia with stripping gas. As the inventors have found in Comparative Examples 1 and 2, the absence of a separation step between the first and second hydrotreating steps (corresponding to the second catalytic zone and the first catalytic zone, respectively) when hydrotreating oxygenated hydrocarbon feedstocks will result in a higher nitrogen content in the feedstock to the isomerization reactor, which in turn leads to a low yield of aviation fuel fractions with a cloud point of -40°C or lower.

[0092] Unexpected discovery Figure 2 and 3Ammonia in the first hydrotreating effluent causes heavy incorporation of nitrogen in the second hydrotreating reactor, and these nitrogen compounds are also unexpectedly resilient to HDN conditions, which leads to the failure of normal removal of any residual ammonia in the stripping step prior to isomerization. This was unexpected for the inventors, who modified the hydrotreating steps by including a separation stage after the first hydrotreating reactor, in a manner that subjectes the second hydrotreating effluent from the second catalytic zone of the hydrotreating reactor to a separation stage (107), wherein at least a portion of the second hydrotreating effluent (106) is separated into a gaseous fraction (121) and a hydrotreating liquid (108).

[0093] The 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 second hydrotreating effluent (106) into a gaseous fraction (121) and a second 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 effectively cooled. From the perspective that less heating is required in the first catalytic zone, it is advantageous not to cool the first hydrotreating effluent. It can also be advantageous if the separated second hydrotreating liquid is used for product recycling to dilute the oxygenated hydrocarbon feedstock.

[0094] The separation stage may also include cryogenic separation, wherein the effluent from the hydrotreatment process is effectively cooled, for example, by a heat exchanger, as this is advantageous from the perspective of being able to separate as much ammonia as possible from the first hydrotreatment liquid. Therefore, cooling may be applied during the separation stage of the second hydrotreatment effluent (106) when the second hydrotreatment liquid (108) is at a temperature lower than the inlet temperature of the first catalytic zone (102) of the hydrotreatment reactor (101), such as at least 100°C lower than the inlet temperature of the first hydrotreatment reactor. For example, cold separation of the first hydrotreatment effluent may be carried out at a temperature between 120 and 200°C.

[0095] The entire amount of the second hydrotreating effluent (106) can be separated, or at least a portion of the second hydrotreating effluent (106) can be separated. For example, the second hydrotreating effluent can be split into two streams, wherein, as described above, one stream is separated into a second hydrotreating liquid (108) and a gaseous fraction (121), and the other stream is used as a hydrocarbon diluent without any separation. In addition to hydrocarbons, the other stream will also include excess hydrogen and all gaseous impurities, including ammonia, which will be reintroduced into the second catalytic zone.

[0096] It is also possible to separate all amounts of the second hydrotreating effluent (106) to avoid the accumulation of ammonia in the second catalytic zone or to avoid the addition of other amounts of ammonia to the second catalytic zone (when the second hydrotreating effluent is used as a product for recycling), which can react with oxygen-containing hydrocarbons to form other nitrogen compounds, which can then exist in the second hydrotreating effluent.

[0097] In the separation stage (107), the second hydrotreating effluent (106) is separated into a gaseous fraction (121) and a second hydrotreating liquid (108). The 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 will be produced from the HDN reaction. The second hydrotreating liquid (108) will contain greater than or equal to 90 wt% hydrocarbons, with 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 second hydrotreating liquid (108) contains greater than or equal to 95 wt% hydrocarbons, such as 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, as it can lead to catalyst coking and other undesirable side effects. Therefore, the conversion can result in the second hydrogenation treatment liquid (108) containing less than or equal to 99 wt% hydrocarbons, that is, hydrogenating the hydrogenation treatment inlet stream to the point that the second hydrogenation treatment liquid (108) contains between 95 and 99 wt% hydrocarbons.

[0098] The remaining components of the first hydrotreating solution will be heteroatom-containing hydrocarbons, such as oxygen-containing or nitrogen-containing hydrocarbons. Even when the initial nitrogen impurities are high, nitrogen will still be retained to a certain extent in the first hydrotreating solution, which may contain more than 1 w ppm of elemental nitrogen, such as more than 5 w ppm and up to 100 w ppm.

[0099] A second hydrogenation treatment liquid (108) containing, for example, 5-100 wppm of nitrogen impurities, or at least a portion thereof, is introduced into the first catalytic zone (102) together with hydrogen-rich gas (120).

[0100] Hydrogen-rich gas (120) is necessary not only in the second catalytic zone (105) as described above, but also in the first catalytic zone (102), particularly for hydrodeoxygenation (HDO) and hydrodenitrification (HDN) reactions. The hydrogen-rich gas can be, for example, excess hydrogen from methods (123, 118) that has been purified by one or more purification steps (122), such as separation (122) into a gaseous fraction (123) containing water, ammonia, and other light substances, followed by ammonia purification and / or membrane separation purification. The purity of the hydrogen-rich gas used in the second catalytic zone is less important than that used in the first catalytic zone (102), for stripping before the isomerization reactor (114), or in the isomerization reactor (103).

[0101] The hydrogen-rich gas used in the first catalytic zone typically has a purity of 90 mol%, usually 95 mol% or higher, and may contain gaseous hydrocarbons. To minimize the risk of nitrogen re-introduction into the first hydrotreating effluent discharged as a product side stream (112), the hydrogen-rich gas used in the first catalytic zone (102) ideally contains very little or no reactive nitrogen, such as ammonia. Specifically, when mixed with the first hydrotreating liquid (127) to form the feed (127+102) to the first catalytic zone (102), the nitrogen content in the hydrogen-rich gas (120) used in the reactor of the first catalytic zone (102) should ideally not cause an increase in the nitrogen content of the liquid phase of the feed (127+102) to the first catalytic zone (102).

[0102] Therefore, the hydrogen-rich gas (120) used in the first catalytic zone (102) may contain nitrogen impurities of less than or equal to 10 wppm or even lower, such as nitrogen impurities of less than or equal to 5 wppm in elemental nitrogen, or nitrogen impurities of less than or equal to 1 wppm in elemental nitrogen.

[0103] If sufficient mass is available, the hydrogen-rich gas can be purified excess hydrogen, a process known as hydrogen recycling. The hydrogen-rich gas can also be fresh hydrogen that has not yet been used in the method, and it can be a mixture of recycled and fresh hydrogen.

[0104] As those skilled in the art will understand, when referring to nitrogen impurities, it is intended to encompass nitrogen impurities that can be considered to react to form new bonds under hydrotreating or hydroisomerizing conditions, i.e., non-inert or reactive nitrogen. For example, according to the invention, nitrogen capable of being incorporated into the products and intermediates of the invention, such as the second hydrotreating effluent (106), the first hydrotreating effluent, or the isomerization effluent (116) discharged as a product side stream (112), is considered a nitrogen impurity. As used in the invention, it is not intended that nitrogen (N2) should be included within the scope of the term nitrogen impurity. Nitrogen impurities can be determined using elemental analysis, and nitrogen impurities cover organic nitrogen, ammonia, and ammonium.

[0105] As mentioned above, the hydrotreating reactor (101) includes a first catalytic zone (102) arranged above the second catalytic zone (105). The first catalytic zone (102) may be a single fixed bed.

[0106] At inlet temperatures and pressures for hydrodeoxygenation and hydronitrogenation that result in at least one side-flowing liquid component containing greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 w ppm nitrogen in elemental nitrogen, preferably less than or equal to 0.4 w ppm nitrogen, such as less than or equal to 0.3 w ppm nitrogen (as determined by ASTM D4629), at least a portion of the second hydrotreating liquid (108, 127) is introduced into the first catalytic zone (102) together with hydrogen-rich gas (120).

[0107] Specifically, the nitrogen content of the liquid component of the product side stream (112) is less than the nitrogen content of the second hydrogenation treatment liquid (108).

[0108] It is neither required nor intended that the second hydrotreating solution be diluted with any diluent, such as hydrocarbons, before or during the hydrotreating in the first catalytic zone (102). Instead, the second hydrotreating solution (108, 127) is used as feed into the second hydrotreating reactor. However, it is possible to mix the second hydrotreating solution (108, 127) with another hydrocarbon feed, provided that the second hydrotreating solution (108, 127) is not mixed with a feed having an oxygen content higher than that of the second hydrotreating solution (108, 127), and wherein the second hydrotreating solution (108, 127) is preferably not mixed with a feed having a nitrogen content greater than or equal to 100 wppm;

[0109] Hydrocarbon diluents are not necessary to control the exothermic characteristics of the hydrotreating reaction in the first catalytic zone. Therefore, diluents, such as hydrocarbon diluents, may be absent in the second hydrotreating reactor, i.e., in some cases, hydrocarbon diluents are not introduced into the first catalytic zone of the hydrotreating reactor (102).

[0110] There are various combinations of inlet temperatures and pressures that will allow HDO and HDN to remove oxygen from the remaining oxygen-containing hydrocarbons, thereby producing water as a byproduct, and further reduce nitrogen impurities compared to the second hydrogenation treatment liquid (108), thereby producing ammonia as a byproduct, and the liquid component of the product side stream (112) contains a lower amount of nitrogen impurities than the second hydrogenation treatment liquid (108).

[0111] Specifically, the inlet temperature in the first catalytic zone (102) is higher than the inlet temperature in the second catalytic zone (105) of the hydrotreating reactor (101).

[0112] For example, the inlet temperature and pressure of the first catalytic zone (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.

[0113] To achieve a deeper HDO and HDN reaction, the inlet temperature of the first catalytic zone (102) is higher than that of the second catalytic zone (105). For example, the inlet temperature of the first catalytic zone (102) can be 10-15°C higher than that of the second catalytic zone (105), or even higher.

[0114] Since the amount of oxygenated hydrocarbons in the second hydrotreating solution (108, 127) is significantly less than that in the hydrotreating inlet stream entering the second catalytic zone (105), this means that the temperature rise in the first catalytic zone (102) is not as high as that in the second catalytic zone (105) due to the fewer exothermic reactions that occur.

[0115] For example, the temperature rise between the reactor inlet and reactor outlet of the second hydrogenation reactor can be small, for example, not exceeding 35°C, or can be considered to be 50% or less of the temperature rise in the first hydrogenation reactor.

[0116] Therefore, the degree of hydrodeoxygenation and hydronitrogenation in the second catalytic zone (105) can be controlled such that the temperature rise between the inlet and outlet of the first catalytic zone (102) does not exceed 10°C. This can be controlled by ensuring sufficient conversion of the oxygen-containing hydrocarbon feed in the first hydrotreating reactor, thereby leaving only a small amount of hydrocarbons with heteroatoms, such as oxygen and nitrogen, in the first hydrotreating liquid, which will subsequently result in a smaller temperature rise due to the amount of material retained after undergoing the exothermic hydrotreating reaction.

[0117] The second catalytic zone (105) in the hydrotreatment reactor (101) may have a lower hydrodeoxygenation activity than the first catalytic zone (102) in the hydrotreatment reactor (101).

[0118] To enhance the hydrotreating activity in the first catalytic zone, as mentioned above, it is possible to increase the temperature to achieve a more complete HDO and HDN reaction. It is also possible to enhance the hydrotreating activity by ensuring that the first catalytic zone (102) has a higher hydrodeoxygenation activity than the second catalytic zone (105).

[0119] Catalytic activity can also be initiated by using the same catalyst in both the first and second catalytic zones, for example, by using a catalyst with the same activity in both reactors. Over time, the second catalytic zone (105) will deactivate faster than the first catalytic zone (102) because a less pure feed, the hydrotreatment inlet stream, is supplied to the second catalytic zone, while a purer feed, the second hydrotreatment liquid (108, 127), is supplied to the first catalytic zone (102). Therefore, the second catalytic zone (105) can have lower hydrodeoxygenation activity than the first catalytic zone (102). Catalytic activity can be measured compared to fresh catalyst.

[0120] In the same way that technicians can select different combinations of temperature and pressure in the second catalytic zone, they will also be able to select one or more suitable catalysts and conditions to cause a more complete HDO and HDN reaction in the first catalytic zone.

[0121] The first catalytic zone of the hydrotreating reactor contains one or more catalysts, which may be selected from supported metal hydrides, such as those 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 supported on a support, such as an alumina support, selected from CoMo, NiMo, NiW, CoNiMo. When the catalyst is selected from Ni, Co, Mo, Ru, Rh, W, or any combination thereof, the catalyst is typically a sulfide, and a source of sulfur is added to or present in the hydrotreating inlet stream and / or the hydrogen-rich gas.

[0122] The first catalytic zone of the hydrotreating reactor can be completed in 0.5-3 hours. -1 For example, 0.5-1.5h -1 It can operate within the range of WHSV and feed rates of 350-2100 Nl H2 / l, such as 500-1500 Nl H2 / l feed rates.

[0123] More general reaction conditions for the first catalytic zone may include a trickle bed reactor comprising both first and second catalytic zones, the catalytic zones comprising a supported molybdenum-containing hydrogenation catalyst, wherein hydrogenation is carried out in the presence of hydrogen at a temperature of 200-400°C and a pressure between 10-150 bar, wherein the WHSV is 0.5-3 h. -1 Within the range of 500-2100 Nl H2 / l feed H2 flow rate.

[0124] A product side stream (112) containing a portion of the first hydrotreating effluent from the first catalytic zone (102) is removed between the first and second catalytic zones. For example, this can be achieved by using one or more overflow weirs or chimneys to allow the exhaust gas ( Figure 1g) is passed downstream to the second catalytic zone (105) and the overflow of the first hydrotreating effluent ( Figure 1 ,l) collect the first hydrotreating effluent through a tray downstream to the second catalytic zone.

[0125] A product sidestream (112) containing liquid and optionally gaseous components can be discharged between the first and second catalytic zones. The liquid component of the sidestream contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 w ppm nitrogen as elemental nitrogen, preferably less than or equal to 0.4 w ppm nitrogen, such as less than or equal to 0.3 w ppm nitrogen (tested by ASTM D4629).

[0126] For example, the product sidestream (112) can be subjected to one or more high-pressure or low-pressure separators, which are known in the art to separate the product sidestream (112) into a liquid fraction and a gaseous fraction. The separation stage can be a completely high-temperature separation stage in which the product sidestream (112) is not effectively cooled. From the perspective of any subsequent steps, such as isomerization steps, which require less heating, it is advantageous not to cool the product sidestream (112).

[0127] The separation stage (114) can be a stripper, which uses a gas, typically hydrogen, to remove impurities from the product side stream (112) or the liquid component of the product side stream (112). Hydrogen is typically used as the stripping gas because the stripping stage serves two purposes: removing impurities and ensuring a certain amount of hydrogen is dissolved in the liquid components of the side stream (112) and the stripping liquid side stream (115), which is beneficial if these liquids begin, for example, a hydroisomerization section, such as an isomerization reactor (103). If stripping is used, the nitrogen content of the liquid components of the product side stream (112) and the stripping liquid side stream (105) is less than the nitrogen content of the second hydrotreating liquid (108).

[0128] Therefore, the product side stream (112) from the first catalytic zone (102) can be stripped with stripping gas (e.g., hydrogen) that has undergone the stripping stage (114), thereby giving the stripping liquid side stream (105) a nitrogen content of less than or equal to 0.4 wppm in elemental nitrogen, such as less than or equal to 0.3 wppm (ASTM D4629 detection limit).

[0129] As mentioned above, a hydrogen stripping stage is beneficial for removing impurities and ensuring a certain amount of hydrogen dissolves in the liquid phase. The stripping stage is particularly useful when the liquid begins, for example, a hydroisomerization stage, such as in an isomerization reactor (103).

[0130] The product sidestream (112) can be used as its own product or further purified by isomerization.

[0131] The product side stream (112) can be isomerized in an isomerization reactor (103) containing at least one catalytic zone, wherein the product side stream (112) and hydrogen-rich gas (120) are introduced into the catalytic zone at an inlet temperature and pressure that results in at least hydroisomerization to produce an isomerized effluent (116), the hydrogen-rich gas may contain less than or equal to 1 ppm (mol / mol) of nitrogen as elemental nitrogen.

[0132] Hydrogen-rich gas (120) is also necessary for carrying out hydrodeoxygenation (HDO) and hydrodenitrification (HDN) in the first and second catalytic zones (102, 105) as described above, and in the isomerization reactor (103).

[0133] The hydrogen-rich gas can be, for example, excess hydrogen from methods (123, 118) that has been purified by one or more purification steps (122), such as separation (122) into a gaseous fraction (123) containing water, ammonia, and other light substances, and subsequent ammonia purification and / or membrane separation purification. The purity of the hydrogen-rich gas used in the isomerization reactor is important.

[0134] The hydrogen-rich gas used in the isomerization reactor has a purity of 95% or higher. This is intended to minimize the risk of poisoning in the catalytic zone of the isomerization reactor. Therefore, the hydrogen-rich gas used in the second hydrotreating reactor ideally contains very little or no reactive nitrogen, such as ammonia.

[0135] Therefore, the hydrogen-rich gas (120) used in the isomerization reactor (103) may contain nitrogen impurities of less than or equal to 1 ppm (mol / mol) based on elemental nitrogen. If of sufficient mass, the hydrogen-rich gas may be purified excess hydrogen, a so-called hydrogen recycle. The hydrogen-rich gas may also be fresh hydrogen that has not yet been used in the method, and it may be a mixture of hydrogen recycle and fresh hydrogen.

[0136] As those skilled in the art will understand, when referring to nitrogen impurities, it is intended to encompass nitrogen impurities that can be considered to react to form new bonds under hydrotreatment or hydroisomerization conditions, i.e., non-inert or reactive nitrogen. For example, according to the invention, nitrogen capable of being incorporated into the products and intermediates of the invention, such as the first or second hydrotreatment effluent or the first isomerization effluent, is considered a nitrogen impurity. As used in the invention, it is not intended that nitrogen (N2) should be within the scope of the term nitrogen impurity. When the isomerization catalyst contains a noble metal catalyst, such as a catalyst containing Pd or Pt, sulfur impurities should be low, even if present.

[0137] The isomerization reactor (103) is a vessel capable of housing at least one catalytic zone. In this invention, a trickle bed reactor is well-suited. 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.

[0138] The isomerization reactor (103) comprises at least one catalytic zone. This catalytic zone can be in its simplest form as a fixed bed of catalyst particles. It can also be multiple fixed beds having the same or different catalyst particles, or it can be a layer of some catalyst particles with different activities and / or compositions. The isomerization reactor (103) can have a single catalytic zone.

[0139] At the inlet temperature and pressure that leads to at least hydroisomerization to produce isomerization effluent (116), the liquid portion (119) of isomerization effluent (116) contains greater than or equal to 30 wt% branched hydrocarbons and / or an increase of greater than or equal to 30 wt% branched hydrocarbons compared to the second hydrotreating liquid, the liquid component of the side stream (112) or stripping side stream (115) is introduced together with hydrogen-rich gas (120) into the isomerization reactor (103), where it contacts at least one catalytic zone.

[0140] There are various combinations of inlet temperature and pressure that will cause the hydroisomerization effluent (116) to contain greater than or equal to 30 wt% branched hydrocarbons and / or an increase of greater than or equal to 30 wt% branched hydrocarbons compared to the second hydrotreatment liquid.

[0141] For example, the inlet temperature and pressure of the isomerization 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.

[0142] The catalytic zone of the first isomerization reactor may contain one or more catalysts comprising a Group VIII metal supported on a carrier, wherein the carrier may be selected from silica, alumina, clay, titanium dioxide, boron oxide, and zirconium oxide, and may be used alone or in mixtures. For example, the carrier may be silica and / or alumina. The Group VIII metal may be, for example, Pd or Pt. Additionally, one or more catalysts may also contain molecular sieves, such as zeolites.

[0143] The isomerization reactor (103) can be used in 0.5-3 hours. -1 Within the range, for example, 0.5-1h -1 Operating within the WHSV range; and at H2 flow rates of 150-800 Nl H2 / l feed, such as at H2 flow rates of 300-500 Nl H2 / l feed.

[0144] The technician knows how to manipulate the above conditions to obtain a degree of hydroisomerization in which the liquid portion (119) of the first isomerization effluent (116) contains more branched hydrocarbons than the liquid component of the product side stream (112). For example, to the extent that the liquid portion (119) 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 hydrotreating liquid.

[0145] The first isomerization liquid can also be isomerized to the extent that the ratio of isoalkanes to n-alkanes is greater than 1, such as 5 to 30 or 15-30.

[0146] The degree of isomerization is typically measured as the difference between the cloud points of the feed and the product. In this paper, it is measured as the difference between the liquid component of the product sidestream (112) and the liquid portion (119) of the isomerized effluent, where the magnitude of the cloud point reduction determines the completeness of the hydroisomerization. Therefore, the cloud point reduction of the first isomerized liquid to that of the liquid portion (119) of the first isomerized effluent from the second hydrotreating liquid can be 10°C or more.

[0147] Generally, a lower cloud point is considered preferable because it delivers excellent cold flow properties. However, hydrocracking also occurs to some extent during hydroisomerization. In the art, hydrocracking often becomes very thorough, resulting in liquid product losses that outweigh the potential for a low 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 observed that the nitrogen impurity content in Comparative Example 1 before entering the isomerization reactor is much higher (0.6–2.9 wppm) compared to Example 1 (less than or equal to 0.3 wppm). This difference in nitrogen content entering the isomerization reactor not only affects the yield of a specific fuel cut but also significantly affects its cold flow properties.

[0148] For example, the side stream can undergo a stripping stage (114), wherein the side stream (116) is stripped with stripping gas (H2), resulting in the stripping side stream (115) having a nitrogen content of less than or equal to 0.4 wppm in elemental nitrogen, such as less than or equal to 0.3 wppm (as determined by ASTM D4629), and a lower amount of nitrogen compared to the side stream (116); the step of isomerizing the stripping side stream (115) can be carried out in an isomerization reactor (103) containing at least one catalytic zone, wherein the stripping side stream (115) having a nitrogen content of less than or equal to 0.3 wppm in elemental nitrogen (as determined by ASTM D4629) and hydrogen-rich gas (120) are introduced into the catalytic zone at a temperature and pressure that results in at least hydroisomerization to produce a first isomerized effluent (116);

[0149] The isomerization effluent from the isomerization reactor (103) undergoes a separation stage, in which the isomerization effluent is separated into a gaseous fraction and an isomerized liquid, 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 stripping side stream (115).

[0150] More general reaction conditions for the isomerization step may include a trickle-bed reactor as the isomerization reactor, comprising a catalytic zone containing a supported hydrogenation catalyst comprising 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 between 20-50 bar, wherein WHSV is present for 0.5-1.5 h. -1 Within the range and at an H2 flow rate of 150-800 Nl H2 / l feed, the cloud point of the liquid portion (119) from the second hydrotreating liquid and reaching the first isomerization effluent is reduced by 10°C or more.

[0151] The isomerized effluent (116) from the isomerization reactor (103) undergoes a separation stage (117), in which the isomerized effluent (116) is separated into a gaseous fraction (118) and an isomerized liquid (119).

[0152] The separation stage (117) 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 isomerized effluent (116) into a gaseous fraction (118) and a first isomerized liquid (119). The separation stage (117) can also be distillation, although it is generally advantageous to separate the gaseous fraction from the liquid portion prior to distillation.

[0153] As mentioned above, the first isomerization liquid contains greater than or equal to 30 wt% branched hydrocarbons and / or the increase in branched hydrocarbons is greater than or equal to 30 wt% compared with the second hydrogenation liquid.

[0154] The isomerized effluent (116) or isomerized liquid (119) can be distilled to produce one or more product fractions. Such fractionation is well known in the art.

[0155] Specifically, the method of the present invention is advantageous because it has been unexpectedly discovered that specific conditions result in the production of a large quantity of high-quality aviation fuel, see Example 1. The aviation fuel fraction contains C8-C16 hydrocarbons, and specifically, the main fraction of the aviation fuel contains C9-C12 hydrocarbons. The aviation fuel fraction can also be identified by its distillation range, for example, having a distillation range between 150-250°C.

[0156] The isomerized liquid can be separated into aviation fuels with a cloud point of at least -25°C or lower, such as -30°C or lower, for example -40°C or lower, such as -47°C or lower.

[0157] Figure 1 The process describes feeding an oxygenated hydrocarbon feedstock (104) mixed with hydrogen-rich gas (120) and a hydrocarbon diluent (126) in the form of a product recycling agent into a second catalytic zone (105) of a hydrotreating reactor (101) comprising a first catalytic zone (102) located upstream of a second catalytic zone (105). In a separator (107), the second hydrotreating effluent (106) is separated into a gaseous fraction (121) and a second hydrotreating liquid (108). The gaseous fraction (121) can be flash-distilled again at a lower temperature in a separator (122) into a gaseous fraction (123), a water-rich fraction (125), and a hydrocarbon-rich fraction (124). The first hydrotreating liquid (108) can be heated (109, 111) and recompressed (110) and mixed with hydrogen-rich gas (120) to form the feed to the first catalytic zone (102), wherein hydrodeoxygenation and hydrodenitrogenation are caused to obtain the first hydrotreating effluent, from which the product side stream (112) can be discharged. The product side stream (112) is stripped with hydrogen-rich gas (120) in a stripper (114) to form a stripped hydrotreating liquid (115), which is mixed with hydrogen-rich gas (120) and fed to an isomerization reactor (103) containing at least one catalytic zone, wherein the stripped hydrotreating liquid (115) is isomerized to obtain an isomerized effluent (116), and the isomerized effluent (116) is separated in a separator (117) into a gaseous fraction (118) and an isomerized liquid (119). The specific arrangement allows for the efficient use of fresh hydrogen in the first catalytic zone for refining, thereby providing refined hydrocarbon products rich in dissolved hydrogen, wherein these products ( Figure 1 Part of the liquid overflow and excess hydrogen (l (liquid overflow)) Figure 1 g) can be used as a hydrocarbon diluent and compensating hydrogen in the downstream hydrotreating process in the second catalytic zone, and / or discharged as a product side stream (112) between the refining and hydrotreating beds and isomerized in the isomerization reactor.

[0158] Figure 2 This is the comparative reactor apparatus mentioned in Example 1 and Table 7. It is similar to... Figure 1 However, the second hydrogenation reactor was omitted. Figure 2The process describes feeding an oxygenated hydrocarbon feedstock (204) mixed with hydrogen-rich gas (220) and a hydrocarbon diluent (226) into a first hydrotreating reactor (201) containing at least one catalytic zone (205). In a separator (207), the first hydrotreating effluent (206) is separated into a gaseous fraction (221) and a first hydrotreating liquid (208). The gaseous fraction (221) can be flash-distilled again at a lower temperature in a separator (222) into a gaseous fraction (223), a water-rich fraction (225), and a hydrocarbon-rich fraction (224). In a stripper (214), a first hydrotreated liquid (208) is stripped with hydrogen-rich gas (220) to form a stripped hydrotreated liquid (215), which is then mixed with the hydrogen-rich gas (220) and fed into a first isomerization reactor (203) containing at least one catalytic zone, wherein the stripped hydrotreated liquid (215) is isomerized to obtain a first isomerized effluent (216), and the isomerized effluent (216) is separated in a separator (217) into a gaseous fraction (218) and a first isomerized liquid (219).

[0159] Figure 3 This is the comparative reactor apparatus mentioned in Example 2 and Table 7. It is similar to... Figure 1 However, it does not include the separation step located between the first and second hydrogenation reactors. Figure 3 An oxygenated hydrocarbon feedstock (304), mixed with hydrogen-rich gas (320) and a hydrocarbon diluent (326) in product recycling form, is described as being fed into a first hydrotreating reactor (301) containing at least one catalytic zone (305). The first hydrotreating effluent (306) is mixed with the hydrogen-rich gas (320) to form the feedstock of a second hydrotreating reactor (302) containing at least one catalytic zone, wherein hydrodeoxygenation and hydrodenitrogenation are caused to obtain a second hydrotreating effluent (330), which is separated in a separator (307) into a gaseous fraction (321) and a second hydrotreating liquid (312). The gaseous fraction (321) can be flashed again in a separator (322) at a lower temperature to form a gaseous fraction (323), a water-rich fraction (325), and a hydrocarbon-rich fraction (324). In a stripper (314), a second hydrotreated liquid (312) is stripped with hydrogen-rich gas (320) to form a stripped hydrotreated liquid (315), which is then mixed with hydrogen-rich gas (320) and fed into a first isomerization reactor (303) containing at least one catalytic zone, wherein the stripped hydrotreated liquid (315) is isomerized to obtain a first isomerized effluent (316), and the isomerized effluent (316) is separated in a separator (317) into a gaseous fraction (318) and a first isomerized liquid (319).

[0160] When describing embodiments of the invention, not all possible combinations and arrangements of embodiments are explicitly described. Nevertheless, the indisputable fact that certain measures are listed in different dependent claims or described in different embodiments does not imply that combinations of these measures cannot be advantageous. The invention contemplates all possible combinations and arrangements of the described embodiments.

[0161] In this document, the inventors intend that the term “comprising”, “comprise”, and “comprises” may optionally be used in each instance as interchangeably with the term “consisting of” (corresponding to “consisting of”, “consist of”, and “consists of”, respectively).

[0162] Example

[0163] Example 1

[0164] Low-quality waste derived from animal fats containing extracted fats such as butter, lard, and chicken fat is used as feedstock for renewable fuel processing. The feedstock is purified through a pretreatment process involving bleaching before being subjected to hydrogenation. Table 1 shows the carbon number distribution of the low-quality animal fat feedstock used prior to pretreatment, as measured by GC according to ISO 15304M.

[0165] Table 1. Carbon number distribution of low-quality animal fat raw materials before pretreatment, analyzed by GC.

[0166]

[0167]

[0168] Table 2. Properties of raw materials before pretreatment

[0169] method nature Animal fat waste EN ISO 12185 Density at 15℃ <![CDATA[913.4kg / m 3 ]]> EN ISO 12185 Density at 50℃ <![CDATA[883.4kg / m 3 ]]> EN ISO 20846 sulfur 71.5ppm ASTM D4629 / D5762 nitrogen 1120ppm ASTM D2710 Bromine index 24g / 100g ISO 3961 iodine value 58 ASTM D3242 Free fatty acids (TAN) 1.00mg KOH / g ENISO12937 water 0.05％

[0170] Table 3. Gel permeation chromatography (GPC) analysis of raw material components before pretreatment.

[0171] Components Amount (wt-%) Oligomers 0.4 Triglycerides 75.3 diglycerides 15.4 monoglycerides 0.4 carboxylic acid 11.1

[0172] The feedstock is pretreated by bleaching before being used as feedstock for hydrotreatment, wherein the amount of nitrogen, calculated as total elemental nitrogen, is reduced to 1000 w-ppm, which is therefore the nitrogen impurity level of the feedstock stream when it is fed into hydrotreatment (see entry “N content in feed to HDO” in Table 4).

[0173] The feedstock containing inorganic and organic nitrogen impurities is processed by hydrogenation. Organic impurities are primarily in the form of organic nitrogen compounds, such as amides and amines, and their analysis is performed on the feedstock. Metallic impurities, such as Ca, Co, Fe, Mg, Mn, Ni, and Zn, are present in amounts less than 1 w-ppm, which is the analytical precision limit for the specific ICP determination used. Similarly, Al and Na impurities are present in amounts less than 2 w-ppm, and phosphorus content is less than 1 w-ppm.

[0174] To illustrate the invention using various amounts of nitrogen, this pretreated feedstock was mixed with palm oil containing 18 w-ppm of nitrogen to obtain six different nitrogen concentrations (25, 75, 150, 300, 500, 1000 w-ppm) used in runs 1-6 of this embodiment.

[0175] As six separate operations, pretreated feedstocks (fresh feed) containing varying amounts of nitrogen are introduced according to... Figure 1 A hydrodeoxygenation (HDO) fixed-bed trickle-bed reactor apparatus was constructed. In the presence of 45,000 kg of NiMo sulfide supported on an alumina carrier (a fresh catalyst with relative HDO activity compared to the fresh HDO catalyst), the reactor was operated at a pressure of 50 bar and a feed rate of 48,000 kg / h for the HDO reactor, with a catalyst bed length of (105) of 1.1 h. -1 The total feed rate WHSV, with an H2 flow rate of approximately 500 Nl H2 / l feed and at the HDO reactor inlet (T IN The measured reaction temperature was approximately 309°C (which resulted in the HDO reactor outlet temperature being approximately 309°C). OUT The HDO reaction was carried out at a temperature of approximately 340°C. The fresh hydrogen feed into the reactor was 28,700 m³. 3 / h(NTP) and the feed volume of low-quality animal fat waste is 57m³. 3 / h. The liquid HDO product is recycled as a diluent (126), and the ratio of product recycling to fresh feed is about 6:1.

[0176] Before being fed into the refining bed (102) located upstream of the HDO bed, the effluent from the HDO reactor undergoes separation into liquid and gas phases in a high-temperature separator. The refining bed is a fixed bed containing the same NiMo sulfide catalyst supported on an alumina support (a fresh catalyst with relative HDO activity compared to the fresh HDO catalyst), serving as the HDO bed, with a catalyst material content of 15,000 kg. The refining bed operates at a pressure of 50 bar and has a duration of approximately 8.2 h based on the total liquefied feed. -1 The feed rate WHSV, and the refining bed inlet temperature (T) INThe temperature is approximately 340°C, which is 31°C higher than the HDO inlet temperature. Hydrogen consumption is approximately 25 vol% of the amount of hydrogen used in the HDO catalyst bed.

[0177] Table 4 shows the usage as follows: Figure 1 The results of the test runs (runs 1-6) of the apparatus shown are as described above, which utilize a combined HDO reactor and a purification bed, wherein gaseous byproducts, including nitrogen-containing compounds, are removed between the two beds. As is evident from Table 4, the nitrogen content after the purification step can be kept low, despite the high nitrogen content of the fresh feed. Low nitrogen levels in the product are desirable for several reasons, specifically because low nitrogen levels affect the isomerization reaction, thereby resulting in better cold-flow properties under the same isomerization conditions compared to the product with high nitrogen levels prior to isomerization (data not shown).

[0178] By altering the processing conditions, specifically increasing the processing temperature of the refining bed, 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 bed generally leads to uncontrollable reactions, resulting in undesirable cold properties in the final isomerization product. After hydrodeoxygenation and refining, the final liquid alkane effluent is hydroisomerized in the isomerization reactor. In the presence of a Pt-SAPO catalyst, at a pressure of 40 bar, for 1.5 h... -1 Isomerization was carried out in a fixed-bed trickle-bed reactor at a WHSV and a reaction temperature of 328°C. The hydrogen-to-feed ratio was 300 standard liters of H2 per liter of feed.

[0179] The extremely low nitrogen content in all experiments resulted in excellent cold properties of the products. After isomerization and separation by distillation, products 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 were obtained, meeting the specifications of ASTM D7566 (2016), Appendix A2, and exhibiting a nitrogen content of less than 772 kg / m³. 3 The aviation fuel fraction has a density (measured according to ASTM 4052 (2018)) and a pour point of less than -40°C (measured according to IP 529). The obtained aviation fuel composition also has a turbidity point of less than -30°C (determined according to ASTM D5771 (2017)) and an excellent yield of approximately 60 wt%.

[0180] Table 4. HDO Reactor and Purifying Bed - Fresh Catalyst - Figure 1

[0181]

[0182] Comparative Example 1

[0183] As an alternative, for the effective removal of undesirable oxygen and nitrogen impurities, tests were conducted based on... Figure 2 The reactor apparatus. Figure 2 In this apparatus, the same feed composition as in Example 1 was used, and the operating conditions (temperature, pressure, catalyst, etc.) were essentially the same as in Example 1, except that there was no downstream refining bed (102) in this reactor apparatus. However, in this example, the entire amount of fresh catalyst (60,000 kg) was placed in a single HDO reactor. The HDO reaction was carried out under the following conditions: 50 bar pressure, HDO reactor feed rate of 48,000 kg / h, and total feed rate WHSV of 0.8 h. -1 The H2 flow rate is approximately 590 N / L H2 / L feed, and the reaction temperature (T) measured at the HDO reactor inlet is... IN The temperature is approximately 308°C, resulting in a temperature (T) at the HDO reactor outlet. OUT The temperature is approximately 340°C. The fresh hydrogen feed into the reactor is 33,400 m³. 3 / h(NTP) and the feed volume of low-quality animal fat waste is 57m³. 3 / h. The liquid HDO product is recycled as a diluent, and the ratio of product recycling to fresh feed is approximately 6:1.

[0184] Table 5 shows the following... Figure 2 The results shown are from operation in a single HDO reactor, where gaseous byproducts including nitrogen-containing compounds are removed after the HDO reactor and before the liquid alkane effluent enters the isomerization section.

[0185] As shown in Table 5, the nitrogen content before all the isomerization reactors running (7-12) was higher than that in Example 1. In Comparative Example 1, the same amount of catalyst was used compared to Example 1, but it was now within a single reactor. This comparison shows that a single reactor cannot remove nitrogen in a similar efficient manner to the case where the catalyst volume is divided into two separate reactors and the gas phase is removed between these two reactors.

[0186] The increased nitrogen content in the feed inevitably leads to an increase in nitrogen in the final liquid alkane effluent entering the isomerization process, and thus results in poor cold properties and yield of the aviation fuel components recovered from the subsequent separation distillation. In run 12, with an initial nitrogen content of 1000 ppm, a turbidity point of approximately -10°C was obtained with a 5 wt% aviation fuel yield.

[0187] Table 5. Single HDO reactor only - fresh catalyst - Figure 2

[0188]

[0189] Comparative Example 2

[0190] Reaction apparatus such as Figure 3 As shown, it is similar to Example 1, except that two HDO reactors are used in series and no gas removal is performed after the first HDO reactor and before the feed (306) enters the second HDO reactor (302) downstream of the first HDO reactor (301). Similar to Figure 1 The catalyst bed of the refining bed is installed inside the second HDO reactor (302). The liquid alkane effluent (306) from the first HDO reactor is directly directed to the second HDO reactor, i.e., after the first HDO reactor and before the liquid alkane effluent enters the second HDO reactor, without removal of gaseous byproducts including nitrogen-containing compounds. The final liquid alkane effluent (312) obtained after the second HDO reactor (302) is directed to a stripper (314) for removal of gaseous impurities and subsequently into the isomerization reactor. The catalyst and reaction conditions are the same as in Example 1.

[0191] The reactor structure is similar to the prior art reactor device described in US 2011 / 0094149 A1.

[0192] As can be seen from Table 6, the nitrogen content of all runs (13-18) resulted in a much higher nitrogen content than that in Example 1.

[0193] According to the discovery Figure 3 The apparatus is capable of reducing the amount of nitrogen impurities at lower initial feed nitrogen contents, for example, about 25 ppm or less. However, when the amount of nitrogen in the fresh feed increases to 150 ppm or higher, the nitrogen retained after HDO and purification increases to 0.8 ppm or higher. The increased nitrogen content during isomerization leads to poor cold properties and yield of the aviation fuel components recovered from the separate distillation after isomerization, in which a turbidity point of about -15°C was obtained with an aviation fuel yield of 10 wt% in run 18 with an initial nitrogen content of 1000 ppm.

[0194] Table 6 - Two HDO Reactors - Fresh Catalyst - Figure 3

[0195]

Claims

1. A method for preparing hydrocarbons from an oxygen-containing hydrocarbon feedstock, the oxygen-containing hydrocarbon feedstock having nitrogen impurities of 10 wppm or higher based on elemental nitrogen, the method comprising: - A hydrotreating reactor comprising a first catalytic zone arranged above a second catalytic zone, wherein a hydrotreating inlet stream comprising an oxygen-containing hydrocarbon feedstock, a hydrogen-rich gas, and optionally a product recycling diluent is introduced into the second catalytic zone through an inlet located between the first and second catalytic zones, where it is mixed with a portion of a first hydrotreating effluent from the first catalytic zone, wherein said portion of the first hydrotreating effluent comprises liquid hydrocarbons having dissolved hydrogen, wherein the second catalytic zone is operated at temperatures and pressures that cause at least hydrodeoxygenation and hydrodenitrogenation to such an extent that the second hydrotreating effluent from the second catalytic zone of the hydrotreating reactor comprises primarily hydrocarbons, and wherein said oxygen-containing hydrocarbon feedstock has been converted to greater than or equal to 95% hydrocarbons; - The second hydrotreated effluent from the second catalytic zone of the hydrotreated reactor undergoes a separation stage, wherein at least a portion of the second hydrotreated effluent is separated into a gaseous fraction and a hydrotreated liquid, wherein the hydrotreated 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 hydrotreatment liquid and hydrogen-rich gas are introduced into the first catalytic zone in the hydrotreatment reactor, the inlet temperature being higher than the inlet temperature in the second catalytic zone of the hydrotreatment reactor; - A product side stream containing a portion of the first hydrotreating effluent from the first catalytic zone is taken out between the first catalytic zone and the second catalytic zone. The product side stream contains liquid and gas components, and the liquid component of the product side stream contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 1 w ppm nitrogen as elemental nitrogen. - Optionally, the product side stream is isomerized in an isomerization reactor containing at least one catalytic zone, wherein the product side stream and a hydrogen-rich gas containing less than or equal to 1 ppm of nitrogen as elemental nitrogen are introduced into the catalytic zone at an inlet temperature and pressure that causes at least hydroisomerization to produce an isomerized effluent. - The isomerization effluent from the isomerization reactor undergoes a separation stage, wherein the isomerization effluent is separated into a gaseous fraction and an isomerized liquid, wherein the isomerized liquid contains greater than or equal to 30 wt% branched hydrocarbons and / or an increase of greater than or equal to 30 wt% in branched hydrocarbons compared to the product sidestream. A portion of the first hydrotreating effluent from the first catalytic zone heats the hydrotreating inlet stream, and The inlet temperature and pressure of the second catalytic zone are 200-400℃ and 10-150 bar, respectively. The inlet temperature and pressure of the first catalytic zone are 250-450℃ and 10-150 bar.

2. The method according to claim 1, wherein the liquid component of the product side stream contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 0.4 wppm nitrogen as elemental nitrogen.

3. The method of claim 1, wherein the product side stream undergoes a stripping stage, wherein the product side stream is stripped with stripping gas H2, thereby resulting in the stripping side stream having less than or equal to 0.4 wppm of nitrogen as elemental nitrogen, and a lower amount of nitrogen compared to the product side stream; - The stripping side stream is isomerized in an isomerization reactor containing at least one catalytic zone, wherein the stripping side stream and a hydrogen-rich gas having less than or equal to 1 ppm of nitrogen as elemental nitrogen are introduced into the catalytic zone at a temperature and pressure that causes at least hydroisomerization to produce an isomerized effluent. - The isomerization effluent from the isomerization reactor undergoes a separation stage, wherein the isomerization effluent is separated into a gaseous fraction and an isomerized liquid, wherein the isomerized liquid contains greater than or equal to 30 wt% branched hydrocarbons.

4. The method of claim 3, wherein the product side stream is stripped with stripping gas H2, thereby resulting in the stripping side stream having nitrogen content less than or equal to 0.3 wppm in elemental nitrogen.

5. The method according to any one of claims 1-4, wherein the isomerized liquid is separated into aviation fuel having a freezing point of -40°C or lower.

6. The method according to any one of claims 1-4, wherein the isomerized liquid is separated into aviation fuel having a freezing point of -47°C or lower.

7. The method according to any one of claims 1-4, wherein cooling is performed during the separation stage of the second hydrotreating effluent to such an extent that the temperature of the hydrotreating liquid is lower than the inlet temperature of the first catalytic zone of the hydrotreating reactor.

8. The method according to any one of claims 1-4, wherein the hydrocarbon diluent and fresh oxygenated hydrocarbon feedstock are not introduced into the first catalytic zone of the hydrotreating reactor.

9. The method according to any one of claims 1-4, wherein the degree of hydrodeoxygenation and hydrodenitrification in the second catalytic zone is controlled by the following manner: in the first catalytic zone, the temperature rise between the inlet and outlet of the first catalytic zone does not exceed 10°C.

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

11. The method according to any one of claims 1-4, wherein the hydrogen-rich gas used in the first catalytic zone 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 second catalytic zone 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 second catalytic zone are 280-360°C and 30-100 bar.

14. The method according to any one of claims 1-4, wherein the second catalytic zone of the hydrogenation reactor comprises one or more catalysts selected from supported hydrides of metals.

15. The method of claim 14, wherein the metal is selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof.

16. The method of claim 14, wherein the second catalytic region comprises one or more catalysts selected from CoMo, NiMo, NiW, and CoNiMo supported on a support.

17. The method of claim 16, wherein the carrier is alumina.

18. The method according to any one of claims 1-4, wherein the hydrogenation reactor operates at a rate of 0.5-3 h. -1 The WHSV range is within the specified range; and the H2 flow rate of the feed is 350-900 Nl H2 / l.

19. The method according to any one of claims 1-4, wherein the inlet temperature and pressure of the first catalytic zone are 300-430°C and 20-120 bar.

20. The method according to any one of claims 1-4, wherein the inlet temperature and pressure of the first catalytic zone are 330-410°C and 30-100 bar.

21. The method according to any one of claims 1-4, wherein the first catalytic zone of the hydrotreating reactor comprises one or more catalysts selected from supported hydrides of metals.

22. The method of claim 21, wherein the metal is selected from Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof.

23. The method of claim 21, wherein the first catalytic region comprises one or more catalysts selected from CoMo, NiMo, NiW, and CoNiMo supported on a support.

24. The method of claim 23, wherein the carrier is alumina.

25. The method according to any one of claims 1-4, wherein the inlet temperature and pressure of the isomerization reactor are 280-370°C and 20-50 bar.

26. The method according to any one of claims 1-4, wherein the catalytic zone of the isomerization reactor comprises one or more catalysts comprising a group VIII metal supported on a support, wherein the support is selected from silica, alumina, clay, titanium dioxide, boron oxide, zirconium oxide, used alone or as a mixture thereof.

27. The method of claim 26, wherein the carrier is silicon dioxide and / or aluminum oxide.

28. The method of claim 15, wherein the one or more catalysts further comprises a molecular sieve.

29. The method of claim 15, wherein the one or more catalysts further comprise zeolite.

30. The method according to any one of claims 1-4, wherein the isomerization reactor operates at a rate of 0.5-1 h. -1 The WHSV range is within the specified range; and the H2 flow rate of the feed is 300-500 Nl H2 / l.

31. The method according to any one of claims 1-4, wherein the isomerized liquid has a ratio of isoalkane to n-alkane greater than 1.

32. The method according to any one of claims 1-4, wherein the isomerization liquid has a ratio of isoalkanes to n-alkanes of 5 to 30.

33. The method according to any one of claims 1-4, wherein the isomerized liquid has a ratio of isoalkanes to n-alkanes of 15 to 30.

34. The method according to any one of claims 1-4, wherein the oxygenated hydrocarbon feedstock has a nitrogen impurity of 300 wppm or higher based on elemental nitrogen.

35. The method according to any one of claims 1-4, wherein the oxygenated hydrocarbon feedstock has a nitrogen impurity of 500 wppm or higher based on elemental nitrogen.

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 second hydrotreating effluent from the second catalytic zone has 100 to 500 wppm or higher nitrogen impurities.

38. The method according to any one of claims 1-4, wherein a product side stream containing a portion of the first hydrotreating effluent from the first catalytic zone is taken out between the first catalytic zone and the second catalytic zone, the product side stream containing a liquid component and a gaseous component, and wherein the liquid component of the product side stream contains greater than or equal to 99 wt% hydrocarbons and less than or equal to 0.3 wppm nitrogen as elemental nitrogen.

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

40. 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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