Methods for producing renewable fuels

Abstract

A process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock, such as animal fat, containing many nitrogen impurities is described. The process involves hydrotreating the oxygenated feedstock in a first hydrotreating bed located downstream of a polishing bed. After the first hydrotreating bed, the gas phase is removed, and the liquid hydrotreating phase is fed together with fresh hydrogen to a polishing bed located upstream of the first hydrotreating bed, which further reduces the nitrogen impurities contained in the polished hydrocarbon product. The specific process setup effectively removes nitrogen impurities from the resulting hydrocarbon product, resulting in an improved cloud point after isomerization. At the same time, the specific configuration efficiently utilizes fresh hydrogen for polishing, providing a polished hydrocarbon compound rich in dissolved hydrogen, where a portion of such product can be used as a hydrocarbon base additive in the hydrotreating bed downstream, and / or can be removed between the polishing and hydrotreating beds and isomerized in an isomerization reactor.

Description

[Technical Field]

[0001] The present invention relates to a process for producing hydrocarbons from oxygenated hydrocarbon feedstock containing nitrogen impurities, and more particularly to the effective utilization of hydrogen in such a process. [Background technology]

[0002] For example, converting petroleum such as crude oil, and renewable oils such as vegetable oils or animal fats, into high-value products such as transportation fuels such as gasoline, aviation fuel, and diesel, involves a hydrogenation process that consumes hydrogen.

[0003] The refining of heavy crude oil, as well as lower-grade vegetable oils and animal fats such as waste animal fats, increases the demand for hydrogen in the hydrogenation process. Therefore, generating, recovering, and purchasing hydrogen for the hydrogenation of oil has a significant impact on the operating costs of refineries.

[0004] The hydrogenation of petroleum and renewable oils uses hydrogen in excess of the theoretical consumption. The hydrogen remaining after the hydrogenation process can be purified and recycled along with fresh hydrogen, so-called make-up hydrogen, to replenish the hydrogen consumed in the hydrogenation process.

[0005] During hydrogenation, many reactions occur to varying degrees depending on the composition of the feedstock. Hydrogenation reactions include double bond hydrogenation, hydrogenated deoxygenation (HDO), hydrogenated desulfurization (HDS), hydrogenated denitrification (HDN), hydrogenated dearomatization (HDAr), hydrogenolysis (HC), and hydrogen isomerization.

[0006] Hydrogen isomerization is typically carried out on bifunctional catalysts that have both metal dehydrogenation and acidic functional groups, such as platinum or palladium catalysts supporting molecular sieves like SAPO-11. The isomerization selectivity of the catalyst is important; that is, if it is undesirable to reduce the average molecular weight of the feed during the hydrogenation process, then the hydrogenolysis that typically occurs to some extent during hydrogen isomerization is suppressed. This involves a balance between the metal dehydrogenation and acidic functional groups, which is sensitive to factors that can shift this balance. Amines are thought to neutralize the strongly acidic sites, leading to lower acidity and activity of the catalyst. Sulfur is known to impair the metal dehydrogenation functional groups of noble metal catalysts.

[0007] Nitrogen is a common impurity in feed, and it is a well-known component of fossil and renewable oils as well as animal fats. Crude oil has been reported to contain an average nitrogen impurity content of 940 w-ppm, with some reaching as high as 7500 w-ppm (Non-Patent Literature 1). It is also not uncommon for animal waste fats to contain 1000 ppm or more of nitrogen. A typical method for treating undesirable impurities in feedstock, such as nitrogen impurities, is to purify the feedstock prior to hydrogenation. Removing water-soluble nitrogen compounds by degumming is typical. However, in the case of animal fats, most nitrogen compounds are oil-soluble and far more difficult to remove than water-soluble nitrogen compounds.

[0008] Patent Document 1 (IFP Energies Nouvelles) describes a method for hydrogenating feed from renewable resources in two catalyst zones using a molybdenum catalyst, where gaseous and liquid effluents from the floor, which have a higher temperature at the outlet than at the inlet due to the exothermic nature of the hydrogenation reaction, are used directly for recycling to heat fresh feed to the catalyst zones. Patent Document 1 exemplifies an invention using high-quality palm oil and soybean oil with small amounts of nitrogen impurities of 15 and 23 ppm, respectively, and mentions that feed from renewable sources generally contains various impurities, such as nitrogen impurities of 1 to 100 ppm and even up to 1 wt%.

[0009] Patent Document 1 describes an example in which the nitrogen content is reduced to about 2% of the original amount, and impurity feed having a nitrogen content outside the typical range of 1 to 100 ppm is not hydrogenated. Comparative Example 1 shows that, under the process conditions described in Patent Document 1, animal fat with a nitrogen content of about 1 wt% is hydrogenated and isomerized, demonstrating that it is possible to hydrogenate impurity feed having a nitrogen content outside the typical range of 1 to 100 ppm. However, the nitrogen content after the hydrogenation and deoxygenation step was about 2 to 5 ppm, and the yield of aviation fuel cut with a high pour point of -10°C after isomerization was only 5% compared to the requirements for aviation fuel.

[0010] Therefore, there is a need for further hydrogenation processes that can effectively hydrogenate oxygenated hydrocarbons having nitrogen impurities outside the typical range of 1-100 ppm and ensure a low nitrogen content in the hydrogenation product. Furthermore, there is a need for a process that can produce high-quality aviation fuel cut with good cold flow characteristics from oxygenated hydrocarbons having nitrogen impurities outside the typical range of 1-100 ppm.

[0011] To remove as much nitrogen as possible, there is also a possibility of further purifying the feed before hydrogenation. However, while purification methods for removing water-soluble nitrogen can be easily implemented, much of the nitrogen content in animal fats is oil-soluble and is very difficult to remove.

[0012] In addition, there is a need for more efficient use of hydrogen that is added in excess and is typically recycled.

Prior Art Documents

Patent Documents

[0013]

Patent Document 1

Non-Patent Documents

[0014]

Non-Patent Document 1

Summary of the Invention

[0015] The present invention has been made in view of the above-described prior art, and an object of the present invention is to provide a process that can improve the quality of a hydrogenated product obtained from an oxygenated hydrocarbon feed containing nitrogen impurities, while at the same time making the use of hydrogen more efficient. In particular, the improved quality includes a low amount of nitrogen impurities in the product and improved low-temperature fluidity characteristics of the isomerized product.

[0016] To solve this problem, the present invention provides a process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities measured as elemental nitrogen of 10 wppm or more, wherein the process includes a reactor (101) including a first catalyst zone / polishing zone (102) disposed upstream of a second catalyst zone / hydrotreating zone (105). The oxygenated hydrocarbon feedstock is fed to the hydrotreating zone, where the effluent from the first hydrotreating zone is purified, and where the purified effluent from the first hydrotreating zone is hydrotreated at a higher temperature in the second hydrotreating zone (102), and the feed to the second hydrotreating zone (102) is not mixed with the oxygenated feedstock, i.e., not mixed with fresh feed.

[0017] Specifically, the present invention is a process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities measured as elemental nitrogen of 10 wppm or more, comprising a hydrotreating reactor (101) comprising a first catalyst zone (102) disposed above a second catalyst zone (105), wherein a hydrotreating inlet stream comprising an oxygenated hydrocarbon feedstock (104), a hydrogen-rich gas (120), and optionally a product recycle diluent (108, 126) is introduced into the second catalyst zone (105) at an inlet between the first catalyst zone (102) and the second catalyst zone (105), which is mixed with a portion of the first hydrotreating effluent from the first catalyst zone, and the second catalyst zone is operated at a temperature and pressure such that the second hydrotreating effluent (106) from the second catalyst zone (105) of the hydrotreating reactor contains mainly hydrocarbons and causes at least hydrodeoxygenation and hydrodenitrogenation, and wherein the hydrotreating reactor (101) in which the oxygenated hydrocarbon feedstock is converted to ≧95% hydrocarbons is included, The second hydrogenation effluent from the second catalyst zone of the hydrogenation reactor is separated into a gaseous fraction (121) and a hydrogenation liquid (108), at least a portion of which is subjected to a separation step (107) in which the hydrogenation liquid contains ≥95 wt% hydrocarbons and >1 wppm nitrogen. At least a portion of the hydrogenation liquid (108) and the hydrogen enrichment gas (120) are introduced into the first catalyst zone (102) in the hydrogenation reactor (101) at an inlet temperature higher than the inlet temperature in the second catalyst zone of the hydrogenation reactor, and at a pressure that causes hydrogenation deoxygenation and hydrogenation denitrification. A product bystream (112) containing a portion of the first hydrogenation effluent from the first catalyst zone (102) is extracted between the first and second catalyst zones, and the product bystream (112) contains liquid and gaseous components, and the liquid component of the bystream contains ≥99 wt% hydrocarbons and, as measured as elemental nitrogen, ≤1 wppm of nitrogen, preferably ≤0.4 wppm of nitrogen, for example ≤0.3 wppm of nitrogen (detected by ASTM D4629), etc. Regarding the process.

[0018] In other words, the inventors of the present invention have found that, in a first embodiment of the present invention, ammonia and other low-boiling amines are removed from the effluent from the second catalyst zone (105) (hydrogenation zone) by separation into gas and liquid phases, and the liquid phase therefrom is then hydrogenated in the first catalyst zone (102) (polishing zone), where this liquid phase is not combined with other oxygenated hydrocarbon feeds and is not combined with other feeds having a higher nitrogen content than the first hydrogenation liquid, thereby enabling efficient hydrogenation of nitrogen-containing oxygenated hydrocarbons in two catalyst zones within a single reactor. At least a portion of the first hydrogenation effluent is taken out as a sidestream and separated into a gaseous stream and a second hydrogenation liquid stream, where the separation may be a stripping step or prior to a stripping step (114), where the first hydrogenation liquid stream may be stripped with a stripping gas to reduce the nitrogen content of the stripped sidestream (115) to 0.3 wppm or less.

[0019] Specifically, the inventors discovered that ammonia present in the hydrogen-enriched effluent gas generated from nitrogen impurities in the feed during the hydrogenation process can be reincorporated into the product during more advanced hydrogenation / hydrogenation conditions if the hydrogen-enriched gas containing such ammonia impurities is used in the polishing process without prior removal of the ammonia impurities.

[0020] By using the policing zone (first catalyst zone) upstream of the hydrogenation zone (second catalyst zone), fresh hydrogen can be utilized more effectively compared to reactors with the policing zone downstream of the hydrogenation zone. This is because the feed to the first catalyst zone (102) (polishing zone) already contains a lower amount of nitrogen compared to the oxygenated hydrocarbon feed to the second catalyst zone (105) (hydrogenation zone), and the fresh hydrogen added to the policing zone does not contain nitrogen impurities present in the effluent from the second catalyst zone, and at the same time, any excess hydrogen present in the effluent from the first catalyst zone (102) (polishing zone) remains of a quality suitable for use in the second catalyst zone (105) (hydrogenation zone).

[0021] The reactor setup and process of the present invention lead to more efficient use of hydrogen while ensuring low levels of nitrogen impurities in the product bystream (112).

[0022] The product bystream (112) may be used as a product of its own, or it may be isomerized in a first isomerization reactor (103) comprising at least one catalyst zone, where the product bystream (112) and a hydrogen-enriched gas (120) having ≤1 ppm (mol / mol) nitrogen as measured as elemental nitrogen are introduced into the catalyst zone at an inlet temperature and pressure that causes at least hydrogen isomerization to produce an isomerization effluent (116), the isomerization effluent from the isomerization reactor is subjected to a separation step (117), where the first isomerization effluent (116) is separated into a gaseous fraction (118) and an isomerized liquid (119), where the first isomerized liquid contains ≥30 wt% branched hydrocarbons and / or an increase of ≥30 wt% branched hydrocarbons compared to the product bystream (112).

[0023] For example, a sidestream is subjected to a stripping step (114), where the sidestream (116) is stripped with a stripping gas (H2) such that the stripped sidestream (115) has a nitrogen content of ≤0.4 wppm, e.g., ≤0.3 wppm (ASTM D4629 detection), and a lower nitrogen content compared to the sidestream (116); this stripped sidestream (115) may be subjected to a step of isomerization in a first isomerization reactor (103) including at least one catalyst zone, where the stripped sidestream (115) and a hydrogen-enriched gas (120) having a nitrogen content of ≤1 ppm (mol / mol), measured as a nitrogen element, are introduced into the catalyst zone at a temperature and pressure that causes at least hydrogenation denitrification to produce a first isomerization effluent (116); Here, the isomerized effluent from the first isomerization reactor (103) is subjected to a separation step (117), where the isomerized effluent is separated into a gaseous fraction and an isomerized liquid, the first isomerized liquid containing ≥30 wt% branched hydrocarbons and / or branched hydrocarbons increased by ≥30 wt% compared to the stripped by-stream (115).

[0024] The isomerized liquid can be separated into at least aviation fuel having a freezing point of -40°C or below, for example, -47°C or below.

[0025] Cooling may be applied during the separation step of the second hydrogenation liquid (106) to such an extent that the second hydrogenation liquid (108) is at a temperature lower than the temperature at the inlet of the first catalyst zone (102) of the first hydrogenation reactor (101).

[0026] Similar to hydrocarbon diluents, fresh oxygenated hydrocarbon feedstock is not intended to be introduced into the first catalytic zone of the hydrogenation reactor (102).

[0027] The degree of hydrogenation deoxygenation and hydrogenation denitrification in the second catalyst zone (105) can be controlled in the first catalyst zone (102) in such a manner that the temperature rise between the inlet and outlet of the first catalyst zone does not exceed 10°C.

[0028] The second catalyst zone (105) in the hydrogenation reactor (101) may have lower hydrogenation deoxygenation activity than the first catalyst zone (102) in the hydrogenation reactor (101).

[0029] The hydrogen enrichment gas (120) used in the first catalyst zone (102) may contain nitrogen impurities of ≤5 wppm, as measured as elemental nitrogen.

[0030] The temperature and pressure at the inlet of the second catalyst zone (105) may be 200-400°C and 10-150 bar, for example 250-380°C and 20-120 bar, for example 280-360°C and 30-100 bar.

[0031] The second catalyst zone of the hydrogenation reactor includes one or more catalysts selected from metal hydrides supported on a support, such as catalysts selected from the group consisting of Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. Preferably, the second catalyst zone may include one or more catalysts selected from CoMo, NiMo, NiW, and CoNiMo supported on a support, such as an alumina support.

[0032] The hydrogenation reactor (101) operates for 0.5 to 3 hours. -1 It can be operated with WHSV in the range of 350-900 Nl H2 / l feeds and with H2 flows.

[0033] The temperature and pressure at the inlet of the first catalyst zone (102) may be 250-450°C and 10-150 bar, for example 300-430°C and 20-120 bar, for example 330-410°C and 30-100 bar.

[0034] The first catalyst zone of the hydrogenation reactor may contain one or more catalysts, which may be selected from metal hydride compounds supported on a support, such as catalysts selected from the group consisting of Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. Preferably, the first catalyst zone contains one or more catalysts selected from CoMo, NiMo, NiW, and CoNiMo supported on a support such as an alumina support.

[0035] The temperature and pressure at the inlet of the isomerization reactor (103) can be 280-370°C and 0-50 bar, respectively.

[0036] The catalyst zone of the isomerization reactor comprises one or more catalysts, which may comprise a group VIII metal supported on a support, where the support is selected from silica, alumina, clay, titanium oxide, boron oxide, and zirconia, which may be used alone or in mixtures, preferably silica and / or alumina.

[0037] The catalyst zone of the isomerization reactor may further contain molecular sieves, such as zeolites.

[0038] The isomerization reactor (103) lasts for 0.5 to 1 hour. -1 It can be operated with WHSV in the range of 300-500 Nl H2 / l feeds and with H2 flows.

[0039] The first isomerized solution may have a ratio of i-paraffin to n-paraffin greater than 1, for example, a ratio of 5-30 or 15-30.

[0040] A portion of the first hydrogenation effluent from the first catalyst zone (102) may be used to heat the hydrogenation inlet flow, for example, by mixing.

[0041] The oxygenated hydrocarbon feedstock may have nitrogen impurities of 300 wppm or more, preferably 500 wppm or more, as measured for elemental nitrogen.

[0042] The hydrogenation treatment inlet stream may contain nitrogen impurities at a concentration of 100-500 wppm.

[0043] The second hydrogenation effluent (106) from the second catalyst zone may contain nitrogen impurities at concentrations of 100-500 wppm or higher. [Brief explanation of the drawing]

[0044] [Figure 1] Figure 1 shows a process scheme comprising a hydrogenation reactor (101) including a first catalyst zone (102) (polishing bed) positioned above a second catalyst zone (105) (hydrogenation bed), and a first isomerization reactor (103). [Figure 2] Figure 2 shows a comparative process scheme that is not according to the present invention, comprising a first hydrogenation reactor (201) and a first isomerization reactor (203). [Figure 3] Figure 3 shows a comparative process scheme that is not according to the present invention, comprising a first hydrogenation reactor (301), a second hydrogenation reactor (302), and a first isomerization reactor (303). [Modes for carrying out the invention]

[0045] Certain terms will be used for clarity when describing embodiments of the present invention. However, the present invention is not intended to be limited to the specific terms thus selected, and each specific term is understood to include all technical equivalents that operate in a similar manner to achieve a similar purpose.

[0046] The present invention is a process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities measured as elemental nitrogen at 10 wppm or more, A hydrogenation reactor (101) comprising a first catalyst zone (102) positioned above a second catalyst zone (105), wherein a hydrogenation inlet flow containing an oxygenated hydrocarbon feedstock (104), a hydrogen enrichment gas (120), and optionally a product recycling diluent (108, 126) is introduced into the second catalyst zone (105) at an inlet between the first catalyst zone (102) and the second catalyst zone (105), and is mixed with a portion of the first hydrogenation effluent from the first catalyst zone, and the second catalyst zone is operated at a temperature and pressure that causes at least hydrogen deoxygenation and hydrogen denitrification to such an extent that the second hydrogenation effluent (106) from the second catalyst zone (105) of the hydrogenation reactor contains mainly hydrocarbons, and wherein the hydrogenation reactor (101) comprises an oxygenated hydrocarbon feedstock converted to ≥95% hydrocarbons. The second hydrogenation effluent from the second catalyst zone of the hydrogenation reactor is separated into a gaseous fraction (121) and a hydrogenation liquid (108), at least a portion of which is subjected to a separation step (107) in which the hydrogenation liquid contains ≥95 wt% hydrocarbons and >1 wppm nitrogen. At least a portion of the hydrogenation liquid (108) and the hydrogen enrichment gas (120) are introduced into the first catalyst zone (102) in the hydrogenation reactor (101) at an inlet temperature higher than the inlet temperature in the second catalyst zone of the hydrogenation reactor, and at a pressure that causes hydrogenation deoxygenation and hydrogenation denitrification. A product bystream (112) containing a portion of the first hydrogenation effluent from the first catalyst zone (102) is extracted between the first and second catalyst zones, and the product bystream (112) contains liquid and gaseous components, and the liquid component of the bystream contains ≥99 wt% hydrocarbons and, as measured as elemental nitrogen, ≤1 wppm of nitrogen, preferably ≤0.4 wppm of nitrogen, for example ≤0.3 wppm of nitrogen (detected by ASTM D4629), etc. Regarding the process.

[0047] In other words, the inventors of the present invention have found that, in a first embodiment of the present invention, ammonia and other low-boiling-point amines are removed from the effluent from the second catalyst zone (105) (hydrogenation zone) by separation into gas and liquid phases, and the liquid phase therefrom is then hydrogenated in the first catalyst zone (102) (polishing zone), where this liquid phase is not combined with other oxygenated hydrocarbon feeds and is not combined with other feeds having a higher nitrogen content than the first hydrogenation liquid, thereby enabling efficient hydrogenation of nitrogen-impregnated oxygenated hydrocarbons in two catalyst zones within a single reactor. At least a portion of the first hydrogenation effluent is taken out as a bystream and separated into a gaseous stream and a second hydrogenation liquid stream, where the separation may be a stripping step or before a stripping step (114), where the first hydrogenation liquid stream has a nitrogen content equal to that of the stripped bystream (115). The nitrogen may be stripped using a stripping gas to reduce it to 0.4 wppm or less, for example, 0.3 wppm or less (ASTM D4629 detectable).

[0048] Specifically, the inventors discovered that gaseous ammonia present in the hydrogen-enriched effluent gas formed from nitrogen impurities in the feed during the hydrogenation process can be reincorporated into the product during more advanced hydrodeoxygenation / hydrodenitrification conditions if the hydrogen-enriched gas containing such ammonia impurities is used in the polishing process without prior removal of the ammonia impurities.

[0049] By using a policing zone (first catalyst zone) upstream of the hydrogenation zone (second catalyst zone), fresh hydrogen can be utilized more effectively compared to reactors with a policing zone downstream of the hydrogenation zone. This is because the feed to the first catalyst zone (102) (polishing zone) already contains a lower amount of nitrogen compared to the oxygenated hydrocarbon feed to the second catalyst zone (105) (hydrogenation zone), and the fresh hydrogen added to the policing zone does not contain nitrogen impurities present in the effluent from the second catalyst zone, and at the same time, any excess hydrogen present in the effluent from the first catalyst zone (102) (polishing zone) remains of a quality suitable for use in the second catalyst zone (105) (hydrogenation zone).

[0050] The reactor setup and process of the present invention lead to more efficient use of hydrogen while ensuring low levels of nitrogen impurities in the product bystream (112).

[0051] This process is for preparing hydrocarbons from oxygenated hydrocarbon feedstocks. Examples of oxygenated hydrocarbon feedstocks include fatty acids and triglycerides, which are abundant in vegetable oils and animal fats. Oxygenated hydrocarbon feedstocks from renewable sources, such as vegetable oils and animal fats, are well-suited to this process. The majority of these vegetable oils and animal fats consist of 25 wt%, 40 wt%, or more free fatty acids or esters of free fatty acids. Examples of esters of free fatty acids include fatty acid glyceride esters (mono-, di-, and / or tri-glycerides) or, for example, fatty acid methyl esters (FAME) or fatty acid ethyl esters (FAEE). Therefore, oxygenated hydrocarbon feedstocks from renewable sources may contain 40 wt% or more fatty acids or fatty acid esters.

[0052] For example, the renewable nature of carbon-containing compositions such as feedstocks and products is due to the feedstock's... 14The C isotope content in the atmosphere in 1950 14 This can be determined by comparing it with the 1C isotope content. 14 C isotope content can be used as proof of the renewable origin of feedstock or product. Carbon atoms in renewable materials are less unstable than radiocarbons compared to carbon atoms of fossil origin. 14 It contains many C atoms. Therefore, 12 C and 14 By analyzing the isotopic ratios of 14C, it is possible to distinguish between carbon compounds from biological sources and those from fossil sources. Therefore, specific isotopic ratios can be used to identify renewable carbon compounds and distinguish them from non-renewable, i.e., fossil carbon compounds. Isotope ratios do not change during chemical reactions. ASTM D6866 (2020) is an example of a suitable method for analyzing the carbon content from biological sources. An example of how ASTM D6866 can be applied to determine the renewable content in fuel is shown in the paper by Dijs et al., Radiocarbon, 48(3), 2006, pp 315-323. For the purposes of this invention, a carbon-containing material, such as feedstock or a product, is considered to be of a renewable origin if, as measured using ASTM D6866, it contains 90% or more of the current standard carbon, e.g., 100% of the current standard carbon.

[0053] Many vegetable oils and animal fats may contain typical amounts of nitrogen impurities, such as between 1 and 100 ppm, and these can also be hydrogenated using the process of the present invention. However, the process of the present invention is advantageous in that the hydrogenation process can convert oxygenated hydrocarbon feedstocks containing high levels of nitrogen impurities, such as 10 wppm or more. For example, 300 wppm to 2500 wppm or more, such as 500 wppm or more, such as 800 wppm or more. Oxygenated hydrocarbon feedstocks may have nitrogen impurities up to, for example, 1500 wppm, or up to 2500 wppm. Examples of oxygenated hydrocarbon feedstocks with high nitrogen impurity are some animal fats, which may contain nitrogen impurities in the range of about 1000 wppm, for example, 600 to 1400 wppm. The oxygenated hydrocarbon feedstock may consist of a mixture of oxygenated hydrocarbons from various sources, if preferred. For example, 50% palm oil containing 23 ppm of nitrogen impurities may be mixed with 50% animal fat containing 1000 ppm of nitrogen impurities to produce an oxygenated hydrocarbon feedstock containing 512 ppm of nitrogen impurities. Thus, the oxygenated hydrocarbon feedstock can be selected from vegetable oils, animal fats, or mixtures thereof.

[0054] Nitrogen impurities are measured as elemental nitrogen. One method for measuring elemental nitrogen is ASTM D4629, used in the range of 0.3–100 wppm, while another method, ASTM D572, may be more suitable in the range above 100 wppm. In this invention, both methods may be used as needed to measure nitrogen impurities as elemental nitrogen.

[0055] A hydrogenation reactor (101) including a first catalyst zone (102) positioned above a second catalyst zone (105) is used in the process, the process including flowing a hydrogenation inlet stream into the second catalyst zone (105) at the inlet between the first catalyst zone (102) and the second catalyst zone (105). The hydrogenation inlet stream comprises an oxygenated hydrocarbon feedstock (104), which may be selected as described above, for example, vegetable oil, animal fat or a mixture thereof containing 10 wppm or more of nitrogen, for example 300 wppm or more of nitrogen, for example 500 to 1500 wppm of nitrogen.

[0056] The oxygenated hydrocarbon feedstock is mixed with a portion of the first hydrogenation effluent from the first catalyst zone and optionally with a product recycling diluent (108, 126). Using a portion of the first hydrogenation effluent from the first catalyst zone as a hydrocarbon diluent is advantageous in that it contains hydrocarbons along with dissolved hydrogen, resulting in more effective hydrodeoxygenation (HDO) and hydrodenitrification (HDN) in the second catalyst zone. Using product recycling (108, 126) as a hydrocarbon diluent is advantageous in that a larger amount of the first hydrogenation effluent products can be drawn as a product bystream (112) compared to using the first hydrogenation effluent as a hydrocarbon diluent.

[0057] Hydrocarbon diluents are well known in the art and are used to control the exothermic properties of hydrogenation reactions (e.g., HDO and HDN reactions). Furthermore, hydrocarbon diluents may contain dissolved hydrogen, which is necessary for efficient hydrogenation, as the catalyst must be in contact with both the oxygenated hydrocarbon feedstock and hydrogen in order for the hydrogenation reaction to proceed.

[0058] Using a portion of the first hydrogenation effluent from the first catalyst zone (Figure 1, I) as a hydrocarbon diluent is advantageous because it will already contain dissolved hydrogen and has a high temperature that can be used to heat the inlet of the second catalyst zone (105).

[0059] Using a mixture of both the first hydrocracking effluent from the first catalyst zone (Figure 1, I) and the recycled product from the second catalyst zone (108, 126), for example at least 10% of both, as a hydrocarbon diluent is advantageous in that the fraction containing dissolved hydrogen is mixed with the recycled product from an earlier stage, thereby increasing the amount of product bystream (112) taken out, and thus increasing the reactor's capacity compared to using only the first hydrocracking effluent (Figure 1, I) as a hydrocarbon diluent.

[0060] A portion of the first hydrogenation effluent from the first catalyst zone (102) may also be used to heat the hydrogenation inlet flow, for example, by mixing.

[0061] As described above, the hydrocarbon diluent may be product recycled (108, 126) or hydrocarbons of fossil or renewable origin. It is typically product recycled and / or the first hydrogenation effluent from the first catalyst zone. The hydrocarbon diluent will typically be added in amounts ranging from 1:1 to 4:1 (total hydrocarbon diluent:total oxygenation feedstock). As mentioned above, the hydrocarbon diluent may be of fossil or renewable origin. Some fossil hydrocarbon feeds may contain large amounts of nitrogen impurities. These fossil hydrocarbon feeds may also be, alone or in mixture with other hydrocarbon diluents, part of a hydrocarbon diluent such as product recycled and / or the first hydrogenation effluent from the first catalyst zone. For example, the hydrocarbon diluent may be a mixture of product recycled and fossil hydrocarbons.

[0062] Product recycling and the first hydrogenation effluent from the first catalyst zone are advantageous for use because they will typically contain dissolved hydrogen related to the hydrogenation reaction, which relies on hydrogen dissolved in the liquid phase.

[0063] The hydrogenation inlet stream may contain nitrogen impurities of 100 wppm or more, e.g., 100-500 wppm, and / or the second hydrogenation effluent (106) from the second catalyst zone may contain nitrogen impurities of 100 wppm or more, e.g., 100-500 wppm or more. The process of the present invention is advantageous in that the hydrogenation process can convert oxygenated hydrocarbon feedstock containing many nitrogen impurities without requiring excessive dilution to reduce the total nitrogen impurities of the hydrogenation inlet stream. This is advantageous because excessive dilution would reduce the amount of oxygenated hydrocarbon feedstock processed by the hydrogenation process. Alternatively, or additionally, the nitrogen content may also be measured in the second hydrogenation effluent (106) from the second catalyst zone, which may still contain nitrogen impurities of 100 wppm or more, e.g., 100-500 wppm or more.

[0064] Regarding the maximum amount of nitrogen impurities that may be present: There may be limitations on how many nitrogen impurities, or how high an amount of impurities, can realistically be removed. Therefore, the second hydrogenation effluent (106) from the hydrogenation inlet stream and / or the second catalyst zone may have nitrogen impurities up to 500 wppm, i.e., the second hydrogenation effluent (106) from the hydrogenation inlet stream and / or the first hydrogenation reactor may have nitrogen impurities between 100 and 500 wppm.

[0065] The hydrogenation inlet flow is introduced together with the hydrogen-enriched gas (120) into the first hydrogenation reactor (101), which has a first catalyst zone (102) located above the second catalyst zone (105).

[0066] The hydrogen-enriched gas (120) is required to carry out the deoxygenation (HDO) and denitrification (HDN) reactions in the first and second catalyst zones (102, 105) of the first hydrogenation reactor (101). The hydrogen-enriched gas may be excess hydrogen from the process (123, 118), purified by one or more purification steps (122), such as separation (122) to a gaseous fraction (123) containing hydrogen, water, ammonia, and other light components, which are subsequently separated by amine scrubbing and / or membrane separation. The purity of the hydrogen enrichment gas used in the second catalyst zone is preferably not as critical as that of the hydrogen enrichment gas used in the first catalyst zone (102), the hydrogen enrichment gas used for stripping before the isomerization reactor (114), or the hydrogen enrichment gas used in the isomerization reactor (103), preferably containing no reactive nitrogen such as ammonia, and for example, containing less than 0.3 wppm of nitrogen as measured as elemental nitrogen. Typically, the hydrogen enrichment gas used for the second catalyst zone may have a purity of 95 mol% or higher, but it may also have a hydrogen purity lower than 95 mol%. Supplemental hydrogen may also be mixed to form the hydrogen enrichment gas, or the hydrogen enrichment gas may consist entirely of supplemental gas.

[0067] The hydrogenation reactor (101) is a vessel capable of accommodating at least two catalyst zones (102, 105). In the present invention, a trickle bed reactor is preferred. The trickle bed reactor involves the downward movement of the hydrogenation inlet flow, while simultaneously being in contact with hydrogen in a parallel or counter-flow manner. An example of a trickle bed reactor is an adiabatic trickle bed reactor.

[0068] The hydrogenation reactor (101) includes a first catalyst zone (102) positioned above a second catalyst zone (105). In its simplest form, the catalyst zone may be a fixed bed of catalyst particles. The catalyst zone may include a single fixed bed, or it may include multiple fixed beds having the same or different catalyst particles, or it may be a number of layers of catalyst particles of different activity and / or composition.

[0069] The first catalyst zone (102) may be a single fixed bed, and / or the second catalyst zone (105) may comprise at least three fixed beds.

[0070] The hydrogenation treatment inlet flow, along with the hydrogen enrichment gas (120), is introduced into the second catalyst zone (105) at the inlet between the first catalyst zone (102) and the second catalyst zone (105).

[0071] The hydrogenation inlet flow, along with the hydrogen-enriched gas (120), is introduced into the second catalyst zone (105) of the hydrogenation reactor at an inlet temperature and pressure that causes at least hydrogen deoxygenation and hydrogen denitrification to such an extent that the second hydrogenation effluent (106) from the second catalyst zone (105) of the hydrogenation reactor contains mainly hydrocarbons.

[0072] There are many different inlet temperature and pressure combinations that will cause HDO and HDN to the extent that oxygen is removed from the oxygenated hydrocarbons, thereby producing water as a byproduct, and nitrogen impurities are removed from the oxygenated hydrocarbons, thereby producing ammonia as a byproduct, thereby yielding products that mainly consist of hydrocarbons.

[0073] For example, the temperature and pressure at the inlet of the second catalyst zone (105) may be 200-400°C and 10-150 bar, e.g., 250-380°C and 20-120 bar, e.g., 280-360°C and 30-100 bar.

[0074] It is common practice for those skilled in the art to select various combinations of temperature and pressure that cause at least hydrodeoxygenation and hydrodenitrification to such an extent that the second hydrotreatment effluent (106) from the second catalyst zone mainly consists of hydrocarbons, the oxygenated hydrocarbon feedstock is converted to ≥95% hydrocarbons, preferably ≥98% hydrocarbons, and ≤2% of the oxygenated hydrocarbon feedstock is present.

[0075] Just as a person skilled in the art can select various combinations of temperature and pressure, a person skilled in the art would also be able to select one or more catalysts suitable for the catalyst zone of the second catalyst zone (105).

[0076] For example, the second catalyst zone of a hydrotreating reactor may include one or more catalysts selected from supported hydrogenation metals such as catalysts selected from the group consisting of Pd, Pt, Ni, Co, Mo, Ru, Rh, W or any combination thereof, and preferably, the second catalyst zone includes one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo supported on a carrier such as an alumina carrier.

[0077] The hydrotreating reactor (101) can be operated at a WHSV in the range of 0.5 to 3 h -1 and a H2 flow of 350 to 900 Nl H2 / l feed.

[0078] More general reaction conditions for the second catalyst zone (105) may include a trickle bed reactor as the hydrotreating reactor, including the second catalyst zone, where the catalyst zone includes a supported hydrogenation catalyst containing molybdenum, and where the hydrotreating is carried out at a temperature of 200 to 400 °C, a pressure between 10 and 150 bar, in the presence of hydrogen, where the WHSV is in the range of 0.5 to 3 h -1 and a H2 flow of 300 to 2100 Nl H2 / l feed.

[0079] The second catalytic zone generates a second hydrogenation effluent (106), which will contain excess hydrogen, water vapor produced from HDO, CO and CO2 produced from the decarboxylation / decarbonylation reaction of carboxylic acids in the oxygenated hydrocarbon feed, and gaseous components in the form of H2S. Finally, NH3 will be produced from the HDN reaction. Much more ammonia (NH3) will be produced in processes where the oxygenated hydrocarbon feedstock contains 300 wppm or more nitrogen than during hydrogenation of a typical feed containing a typical amount of nitrogen, for example, 1-100 ppm, such as palm oil which may contain 23 ppm nitrogen. Surprisingly, the inventors found that when the hydrogenation effluent is subjected to further hydrogenation steps with added makeup hydrogen, the increased amount of ammonia in the hydrogenation effluent particularly causes nitrogen reuptake. In other words, the inventors confirmed that the further hydrogenation effluent from the additional hydrogenation process still contained 2–5 ppm of nitrogen even after stripping with hydrogen gas. This meant that, even with the desire to remove nitrogen as completely as possible before contact with the isomerization catalyst, it was simply impossible to reduce the nitrogen content to less than 2–5 ppm, even after stripping. This was highly unexpected because the additional hydrogenation process was carried out at higher temperatures with the specific expectation that it would perform more advanced HDO and HDN hydrogenation, thereby removing more oxygen and nitrogen from the second hydrogenation effluent. Furthermore, even if ammonia reacted under the conditions of the additional hydrogenation process to produce amines or amides, and even if there was a theoretical possibility that such nitrogen compounds would be formed, it was expected that the hydrocarbons already formed should be inert to any reaction with ammonia, even if these products underwent further hydrodenitrification (HDN) to remove ammonia from them. Surprisingly, however, it was found that nitrogen compounds that did not disappear under the hydrogenation conditions of the additional hydrogenation process were regenerated. These compounds were secondary and tertiary amides.

[0080] As is known in the art, nitrogen can inactivate isomerization catalysts, and therefore, ammonia in the effluent heading toward the isomerization reactor is typically stripped with a stripping gas, and dissolved ammonia is replaced / stripped by the stripping gas, thereby removing any remaining nitrogen. As the inventors found in Comparative Examples 1 and 2, the absence of a separation step between the first and second hydrogenation steps (corresponding to the second catalyst zone and the first catalyst zone, respectively) when hydrogenating oxygenated hydrocarbon feedstock results in a higher nitrogen content being supplied to the isomerization reactor, resulting in a decrease in the yield of aviation fuel cut with a cloud point of -40°C or below.

[0081] It was an unexpected discovery that the ammonia in the first hydrogenation effluent in Figures 2 and 3 caused nitrogen reuptake into the second hydrogenation reactor, and that these nitrogen compounds were also unexpectedly tolerant to HDN conditions, rendering the conditions that normally cause the removal of residual ammonia in the stripping step before isomerization ineffective. This was surprising to the inventors, and they modified the hydrogenation process by including a separation step after the first hydrogenation reactor, so that the second hydrogenation effluent from the second catalyst zone of the hydrogenation reactor is subjected to a separation step (107), where at least a portion of the second hydrogenation effluent (106) is separated into a gaseous fraction (121) and a hydrogenation liquid (108).

[0082] The separation step (107) may be one or more high-pressure or low-pressure separators known in the art to be capable of separating, for example, a second hydrogenation effluent (106) into a gaseous fraction (121) and a second hydrogenation liquid (108). Hydrogen stripping may be used for separation (not shown in the drawings). The separation step may be a high-temperature separation step overall, where the effluent is not actively cooled. Not cooling the first hydrogenation effluent is beneficial in that less heating is required in the first catalyst zone. It may also be beneficial if the separated second hydrogenation liquid is used for product recycling to dilute the oxygenated hydrocarbon feedstock.

[0083] The separation step may also include low-temperature separation, in which the hydrogenation effluent is actively cooled, for example by a heat exchanger, since it is beneficial in terms of separating as much ammonia as possible from the first hydrogenation effluent. Therefore, cooling may be applied during the separation step of the second hydrogenation effluent (106) to such an extent that the second hydrogenation effluent (108) is at a temperature lower than the inlet temperature of the first catalyst zone (102) of the hydrogenation reactor (101), for example, at least 100°C lower than the inlet temperature of the first hydrogenation. Low-temperature separation of the first hydrogenation effluent may be carried out at a temperature between 120 and 200°C, for example.

[0084] The entirety of the second hydrogenation effluent (106), or at least a portion of the second hydrogenation effluent (106), can be separated. For example, the second hydrogenation effluent may be split into two streams, one of which is separated into the second hydrogenation liquid (108) and gaseous fraction (121) as described above, and the other stream is used as a hydrocarbon diluent without separation. The other stream contains hydrocarbons, as well as excess hydrogen and all gaseous impurities, including ammonia, which will be reintroduced into the second catalyst zone.

[0085] The entire amount of the second hydrogenation effluent (106) can be separated in order to avoid the accumulation of ammonia in the second catalyst zone, which may react with oxygenated hydrocarbons to form further nitrogen compounds and thus may be present in the second hydrogenation effluent, or to avoid the addition of further amounts of ammonia to the second catalyst zone (if the second hydrogenation effluent is used for product recycling).

[0086] In the separation step (107), the second hydrogenation effluent (106) is separated into a gaseous fraction (121) and a second hydrogenation liquid (108). The gaseous fraction (121) will contain excess hydrogen, water vapor produced from HDO, CO and CO2 produced from the decarboxylation / decarbonylation of carboxylic acids in the oxygenated hydrocarbon feed, as well as H2S. Finally, NH3 will be produced from the HDN reaction. The second hydrogenation liquid (108) will contain ≥90 wt% hydrocarbons, with the remainder being heteroatom-containing hydrocarbons, such as unreacted oxygenated hydrocarbons. It is desirable that the hydrogenation be as complete as possible, i.e., that the second hydrogenation liquid (108) contains ≥95 wt% hydrocarbons, e.g., ≥98 wt% hydrocarbons. However, completely hydrogenating the hydrogenation inlet flow without increasing the severity of the reaction conditions, which can cause catalyst coking and other undesirable side effects, is not always feasible or possible. Therefore, the conversion can also be carried out so that the hydrogenation inlet flow is hydrogenated to such an extent that the second hydrogenation liquid (108) contains ≤99 wt% hydrocarbons, i.e., to such an extent that the second hydrogenation liquid (108) contains 95-99 wt% hydrocarbons.

[0087] The remaining components of the first hydrogenation solution would be heteroatom-containing hydrocarbons, such as oxygenated hydrocarbons or nitrogen-containing hydrocarbons. If the initial nitrogen impurities are very high, nitrogen is still expected to remain to some extent in the first hydrogenation solution and, measured as elemental nitrogen, may contain nitrogen at >1 wppm, e.g., >5 wppm, and up to 100 wppm.

[0088] For example, a second hydrogenation solution (108) containing 5 to 100 wppm of nitrogen impurities, or at least a portion of the second hydrogenation solution (108), is introduced into the first catalyst zone (102) together with a hydrogen enrichment gas (120).

[0089] The hydrogen-enriched gas (120) is required not only in the second catalyst zone (105) but also in the first catalyst zone (102), as described above, to carry out the hydrodeoxygenation (HDO) and hydrodenitrification (HDN) reactions. The hydrogen-enriched gas may be excess hydrogen from the process (123, 118), purified by one or more purification steps (122), such as separation (122) into a gaseous fraction (123) containing water, ammonia, and other light components, followed by amine scrubbing and / or membrane separation. The purity of the hydrogen-enriched gas used in the second catalyst zone is not as critical as the purity of the hydrogen-enriched gas used in the first catalyst zone (102), the hydrogen-enriched gas used for stripping before the isomerization reactor (114), or the hydrogen-enriched gas used in the isomerization reactor (103). The hydrogen enrichment gas used for the first catalyst zone typically has a purity of 90 mol%, often 95 mol%, or higher, and may contain gaseous hydrocarbons. To minimize the risk of nitrogen reabsorption into the first hydrogenation effluent and removal as a product by-flow (112), the hydrogen enrichment gas (120) used for the first catalyst zone (102) ideally contains little to no reactive nitrogen, such as ammonia. Specifically, the nitrogen content in the hydrogen enrichment gas (120) used for the first catalyst zone (102) should ideally not cause an increase in the nitrogen content of the liquid phase of the feed (127+102) for the first catalyst zone (102) when mixed with the first hydrogenation liquid (108) to form the feed (127+102) for the first catalyst zone (102).

[0090] Therefore, the hydrogen enrichment gas (120) used in the first catalyst zone (102) may contain nitrogen impurities measured as nitrogen element, such as ≤10 wppm or less, such as ≤5 wppm, or such as ≤1 wppm.

[0091] The hydrogen-enriched gas may be purified excess hydrogen gas, or so-called hydrogen recycled gas, provided it is of sufficient quality. Alternatively, the hydrogen-enriched gas may also be fresh hydrogen that has not yet been used in the process, or a mixture of hydrogen recycled gas and fresh hydrogen.

[0092] As those skilled in the art will understand, when referring to nitrogen impurities, it is intended to include nitrogen impurities that are thought to react to form new bonds under hydrogenation or hydrogen isomerization conditions, i.e., non-inert or reactive nitrogen. For example, nitrogen that can be taken out as a product by-stream (112) or isomerization effluent (116) and incorporated into the products and intermediates of the present invention, such as the second hydrogenation effluent (106) and the first isomerization effluent, is considered a nitrogen impurity according to the present invention. Nitrogen gas (N2) is not intended to correspond to the term nitrogen impurity when used in the present invention. Nitrogen impurities can be measured by elemental analysis and include organic nitrogen, ammonia, and ammonium.

[0093] As referenced above, the hydrogenation reactor (101) comprises a first catalyst zone (102) located above the second catalyst zone (105). The first catalyst zone (102) may be a single fixed bed.

[0094] At least a portion of the second hydrogenation liquid (108, 127) is introduced into the first catalyst zone (102) along with the hydrogen enrichment gas (120) at an inlet temperature and pressure that causes at least hydrogenated deoxygenation and hydrogenated denitrification to such an extent that the by-stream liquid component contains ≥99 wt% hydrocarbons and ≤1 wppm of nitrogen, preferably ≤0.4 wppm of nitrogen, for example ≤0.3 wppm of nitrogen (ASTM D4629 detection) as measured as elemental nitrogen.

[0095] Specifically, the nitrogen content of the liquid component of the sidestream (112) is lower than that of the second hydrogenation treatment liquid (108).

[0096] The second hydrogenation solution does not need to be, nor is it intended to be, diluted with any diluent, such as hydrocarbons, before or during hydrogenation in the first catalyst zone (102). Rather, the second hydrogenation solution (108, 127) is used as feed to the second hydrogenation reactor. However, the second hydrogenation solution (108, 127) can be mixed with other hydrocarbon feeds, provided that the second hydrogenation solution (108, 127) is not mixed with a feed having a higher oxygen content than the second hydrogenation solution (108, 127), and the first hydrogenation solution is not mixed with a feed having a nitrogen content of ≥5 wppm.

[0097] Hydrocarbon diluents are not necessary to control the exothermic properties of the hydrogenation reaction in the first catalyst zone. Therefore, diluents such as hydrocarbon diluents do not necessarily need to be present in the second hydrogenation reactor; in other words, hydrocarbon diluents may not be introduced into the first catalyst zone of the hydrogenation reactor (102) in some cases.

[0098] There are many different inlet temperature and pressure combinations that will cause HDO and HDN to the extent that oxygen is removed from the remaining oxygenated hydrocarbons, thereby producing water as a byproduct, and nitrogen impurities are further reduced compared to the second hydrogenation liquid (108), thereby producing ammonia as a byproduct, and a liquid component of the product bystream (112) containing lower amounts of nitrogen impurities than the second hydrogenation liquid (108).

[0099] In particular, the inlet temperature in the first catalyst zone (102) is higher than the inlet temperature in the second catalyst zone (105) of the hydrogenation reactor (101).

[0100] For example, the inlet temperature and pressure in the first catalyst zone (102) may be 250-450°C and 10-150 bar, e.g., 300-430°C and 20-120 bar, e.g., 330-410°C and 30-100 bar.

[0101] To induce more advanced HDO and HDN reactions, the inlet temperature of the first catalyst zone (102) is higher than that of the second catalyst zone (105). For example, the inlet temperature of the first catalyst zone (102) may be 10-15°C higher than that of the second catalyst zone (105), or even higher.

[0102] Because the amount of oxygenated hydrocarbons in the second hydrogenation liquid (108, 127) is significantly less than the hydrogenation inlet flow to the second catalyst zone (105), exothermic reactions are less likely to occur. This means that the temperature rise in the first catalyst zone (102) is not as high as that in the second catalyst zone (105).

[0103] For example, the temperature rise between the reactor inlet and outlet of the second hydrogenation reactor may be small, for example, not higher than 35°C, or less than 50% of the temperature rise in the first hydrogenation reactor.

[0104] Therefore, the degree of hydrogenation deoxygenation and hydrogenation denitrification in the second catalyst zone (105) can be controlled in the first catalyst zone (102) in such a manner that the temperature rise between the inlet and outlet of the first catalyst zone does not exceed 10°C. This can be controlled by ensuring sufficient conversion of the oxygenated hydrocarbon feed in the first hydrogenation reactor and leaving only a small amount of hydrocarbons having heteroatoms, such as oxygen and nitrogen, in the first hydrogenation solution (which will result in a smaller temperature rise due to the remaining amount of material undergoing the exothermic hydrogenation reaction).

[0105] The second catalyst zone (105) in the hydrogenation reactor (101) may have lower hydrogenation deoxygenation activity than the first catalyst zone (102) in the hydrogenation reactor (101).

[0106] To enhance the hydrogenation activity in the first catalyst zone, the temperature can be increased as described above to obtain more advanced HDO and HDN reactions. It is also possible to enhance the hydrogenation activity by ensuring that the first catalyst zone (102) has higher hydrogenation deoxygenation activity than the second catalyst zone (105).

[0107] The catalytic activity can also be started to be the same in both the first and second catalytic zones, for example, by using catalysts 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 more impure feed, the hydrogenation inlet flow, is supplied to the second catalytic zone, compared to a purer feed, the second hydrogenation liquid (108, 127), supplied to the first catalytic zone (102). Thus, the second catalytic zone (105) may have lower hydrogenation deoxygenation activity than the first catalytic zone (102). The catalytic activity can be measured in comparison to a fresh catalyst.

[0108] Just as a person skilled in the art can select various combinations of temperature and pressure to induce more advanced HDO and HDN reactions, a person skilled in the art can also select one or more appropriate catalysts and conditions to induce more advanced HDO and HDN reactions in the first catalytic zone.

[0109] The first catalyst zone of the hydrogenation reactor may include one or more catalysts selected from metal hydrides supported on a support, such as catalysts selected from the group consisting of Pd, Pt, Ni, Co, Mo, Ru, Rh, W, or any combination thereof. For example, the catalyst zone may include one or more catalysts selected from CoMo, NiMo, NiW, CoNiMo, supported on a support such as an alumina support. When the catalyst is selected from the group consisting of Ni, Co, Mo, Ru, Rh, W, or any combination thereof, typically the catalyst is sulfurized, and a sulfur source is added to or present in the hydrogenation inlet stream and / or hydrogen-enriched gas.

[0110] The first catalyst zone of the hydrogenation reactor lasts 0.5 to 3 hours. -1 For example, 0.5 to 1.5 hours -1 It can be operated with WHSV in the range of 350-2100 Nl H2 / l feeds, and with H2 flows of, for example, 500-1500 Nl H2 / l feeds.

[0111] More general reaction conditions for the first catalyst zone may involve a trickle bed reactor comprising first and second catalyst zones, the catalyst zone comprising a supported hydrogenation catalyst containing molybdenum, where the hydrogenation process is carried out in the presence of hydrogen at a temperature of 250-400°C and a pressure between 10-150 bar, where WHSV is 0.5-3h -1 This range is and represents an H2 flow of 500-2100 Nl H2 / l feed.

[0112] A product bystream (112) containing a portion of the first hydrogenation effluent from the first catalyst zone (102) is removed between the first and second catalyst zones. The first hydrogenation extract may be collected in a tray equipped with one or more overflow weirs or chimneys, for example, to allow the effluent gas (Figure 1, g) to pass downstream to the second catalyst zone (105), and to allow the overflow of the first hydrogenation extract (Figure 1, I) to pass downstream to the second catalyst zone.

[0113] The product bystream (112), which includes liquid and optionally gaseous components, can be removed between the first and second catalyst zones. The liquid component of the bystream contains ≥99 wt% hydrocarbons and, as measured as elemental nitrogen, ≤1 wppm of nitrogen, preferably ≤0.4 wppm of nitrogen, for example ≤0.3 wppm of nitrogen (ASTM D4629 detection).

[0114] The product bystream (112) can be subjected to one or more high-pressure or low-pressure separators known in the art, for example, to separate the product bystream (112) into a liquid fraction and a gaseous fraction. The separation step may be a complete high-temperature separation step in which the product bystream (112) is not actively cooled. Not cooling the product bystream (112) is beneficial in that less heating is required in any subsequent steps, such as an isomerization step.

[0115] The separation step (114) may be a stripper, using a gas, usually hydrogen, to remove impurities from the product bystream (112) or the liquid component of the product bystream. Hydrogen is usually used as the stripping gas because the stripping step serves both purposes: to remove impurities and to ensure that a certain amount of hydrogen dissolves in the liquid component of the product bystream (112) and / or the stripped liquid bystream (115) (which is beneficial if these liquids are transported to a hydrogen isomerization step, such as a first isomerization reactor (103). The nitrogen content of the liquid component of the product bystream (112) and the stripped liquid bystream (115), if stripping is used, is lower than the nitrogen content of the second hydrogenation liquid (108).

[0116] Therefore, the product bystream (112) from the first catalyst zone (102) is stripped using a stripping gas (e.g., hydrogen) that is subjected to the stripping step (114), thereby the stripped liquid bystream (115) having, as measured as nitrogen, ≤0.4 wppm of nitrogen, e.g., ≤0.3 wppm of nitrogen (ASTM D4629 detection limit).

[0117] As described above, the hydrogen-based stripping step is useful for removing impurities and ensuring that a certain amount of hydrogen dissolves in the liquid phase. The stripping step is particularly useful when the liquid is transported to a hydrogen isomerization step, such as an isomerization reactor (103).

[0118] The by-product (112) may be used as the product itself, or it may be further purified by isomerization.

[0119] The product bystream (112) may be isomerized in an isomerization reactor (103) having at least one catalyst zone, where the product bystream (112) and a hydrogen-enriched gas (120) (where the hydrogen-enriched gas may contain ≤1 ppm (mol / mol) nitrogen as measured as elemental nitrogen) are introduced into the catalyst zone at an inlet temperature and pressure that causes at least hydrogen isomerization to produce an isomerized effluent (116).

[0120] The hydrogen-enriched gas (120) is also necessary for hydrogenated deoxygenation (HDO) and hydrogenated denitrification (HDN) in the first and second catalyst zones (102, 105), as described above, and also in the isomerization reactor (103).

[0121] The hydrogen-enriched gas may be excess hydrogen from process (123, 118) purified by one or more purification steps (122), such as separation (122) to a gaseous fraction (123) containing water, ammonia, and other light components, followed by amine scrubbing and / or membrane separation. The purity of the hydrogen-enriched gas used in the first isomerization reactor is important.

[0122] The hydrogen-enriched gas used for the isomerization reactor has a purity of 95% or higher. This is intended to minimize the risk of poisoning the catalyst zone of the isomerization reactor. Therefore, the hydrogen-enriched gas used for the second hydrogenation reactor ideally contains little to no reactive nitrogen, such as ammonia.

[0123] Therefore, the hydrogen-enriched gas (120) used in the isomerization reactor (103) may contain nitrogen impurities of ≤1 ppm (mol / mol) as measured as elemental nitrogen. The hydrogen-enriched gas may also be purified excess hydrogen gas, so-called hydrogen recycled gas, provided it is of sufficient quality. Alternatively, the hydrogen-enriched gas may also be fresh hydrogen that has not yet been used in the process, or a mixture of hydrogen recycled and fresh hydrogen.

[0124] As those skilled in the art will understand, when referring to nitrogen impurities, it is intended to include nitrogen impurities that are thought to react to form new bonds under hydrogenation or hydroisomerization conditions, i.e., non-inert or reactive nitrogen. For example, nitrogen that can be incorporated into the products and intermediates of the present invention, such as the first or second hydrogenation effluent or the first isomerization effluent, is considered a nitrogen impurity according to the present invention. It is not intended that nitrogen gas (N2) should correspond to the term nitrogen impurity when used in the present invention. If the isomerization catalyst includes a noble metal catalyst, such as a catalyst containing Pd or Pt, sulfur impurities should be present, if any, in small amounts.

[0125] The isomerization reactor (103) is a vessel capable of housing at least one catalyst zone. In the present invention, a trickle bed reactor is preferred. The trickle bed reactor involves the downward movement of the feed, while simultaneously being in contact with hydrogen in a co-flow or counter-flow manner. An example of a trickle bed reactor is an adiabatic trickle bed reactor.

[0126] The isomerization reactor (103) includes at least one catalyst zone. In its simplest form, such a catalyst zone may be a fixed bed of catalyst particles. It may also be a plurality of fixed beds having the same or different catalyst particles, or a plurality of layers of catalyst particles of different activity and / or composition. The first isomerization reactor (103) may comprise a single catalyst zone.

[0127] The liquid component of the sidestream (112) or the stripped sidestream (115), together with the hydrogen-enriched gas (120), is introduced into the isomerization reactor (103), where it is brought into contact with at least one catalyst zone at an inlet temperature and pressure that causes at least hydrogen denitrification to produce the isomerization effluent (116) to such an extent that the liquid portion (119) of the isomerization effluent (116) contains ≥30 wt% branched hydrocarbons and / or an increase of ≥30 wt% branched hydrocarbons compared to the second hydrogenation effluent.

[0128] There are many different inlet temperature and pressure combinations that will cause hydrogenation denitrification to the extent that the isomerized effluent (116) contains ≥30 wt% branched hydrocarbons and / or an increase of ≥30 wt% branched hydrocarbons compared to the second hydrogenation liquor.

[0129] For example, the temperature and pressure at the inlet of the isomerization reactor (103) may be 250-40°C and 20-50 bar, for example, 280-370°C and 20-50 bar, or 295-370°C and 25-50 bar.

[0130] The catalyst zone of the first isomerization reactor may contain one or more catalysts comprising a group VIII metal supported on a support, where the support may be selected from silica, alumina, clay, titanium oxide, boron oxide, and zirconia, which may be used individually or in mixtures. For example, the support may be silica and / or alumina. Furthermore, one or more catalysts may further contain molecular sieves such as zeolites.

[0131] The isomerization reactor (103) lasts for 0.5 to 3 hours. -1 In WHSV in the range of 150-800 Nl H2 / l feed, and with H2 flow, for example, 0.5-1h -1 WHSV can be operated with an H2 flow of 300-500 Nl H2 / l feed.

[0132] Those skilled in the art will know how to manipulate the above conditions to obtain a degree of hydrogenation isomerization in which the liquid portion (119) of the first isomerized effluent (116) contains more branched hydrocarbons compared to the liquid component (112) of the product bystream. For example, to such an extent that the liquid portion (119) of the first isomerized effluent (116) contains ≥30 wt% branched hydrocarbons and / or an increase of ≥30 wt% of branched hydrocarbons compared to the second hydrogenation effluent.

[0133] The first isomerization solution can also be isomerized to such an extent that the ratio of isoparaffin to n-paraffin is greater than 1, for example, 5-30, or 15-30.

[0134] The degree of isomerization is often measured as the difference in cloud point between the feed and the product, in this case between the liquid component of the product bystream (112) and the liquid portion of the isomerized effluent (119), where the magnitude of the decrease in cloud point determines how extensive the hydrogen isomerization was. Thus, the first isomerized solution can be isomerized to such an extent that the decrease in cloud point from the second hydrogenated solution to the liquid portion of the first isomerized effluent (119) is 10°C or more.

[0135] Generally, a lower cloud point is considered better, as this will result in good cold flow characteristics. However, under hydrogen isomerization conditions, some degree of hydrocracking also occurs. In this art, there are often cases where hydrocracking proceeds too far, and the loss of liquid products outweighs the potential for lowering the cloud point. The catalyst and any impurities it contains, as well as the conditions of hydrogen isomerization, are among the parameters that can affect the degree of hydrogen isomerization and hydrocracking. Referring to Comparative Example 1 and Example 1, it can be seen that the nitrogen impurity before entering the isomerization reactor is much higher in Comparative Example 1 (0.6~2.9 wppm) compared with Example 1 (≤0.3 wppm). Such a difference in nitrogen content into the isomerization reactor not only affects the yield of specific fuel cuts but also has a significant impact on its cold flow characteristics.

[0136] For example, the sidestream is subjected to the stripping stage (114), where the sidestream (116) is stripped with stripping gas (H2) such that the stripped sidestream (115) has a lower amount of nitrogen compared to sidestream (116), for example, ≤0.3 wppm nitrogen (ASTM D4629 detection), and the sidestream (115) is stripped with stripping gas (H2) and measured as nitrogen element, for example, ≤0.3 wppm nitrogen (ASTM D4629 detection); the sidestream (115) is stripped with stripping gas (H2) A stripped hydrogen-enriched gas (120) having D4629 detection is introduced into a catalyst zone at a temperature and pressure that causes hydrogen isomerization to produce a first isomerized effluent (116), and the stripped sidestream (115) is subjected to the step of isomerizing in an isomerization reactor (103) having at least one catalyst zone; the isomerized effluent from the isomerization reactor (103) is subjected to a separation step, where the isomerized effluent is separated into a gaseous fraction and an isomerized liquid, the first isomerized liquid containing ≥30 wt% branched hydrocarbons and / or an ≥30 wt% increase in branched hydrocarbons compared to the stripped sidestream (115).

[0137] More general reaction conditions for the isomerization step may include a trickle bed reactor as the isomerization reactor, comprising a catalyst zone containing a supported hydrogenation catalyst comprising W, Pt, or Pd, and a zeolite, where hydrogen isomerization is carried out in the presence of hydrogen at a temperature of 295–370°C and a pressure between 20–50 bar, such that the decrease in the cloud point of the first isomerized effluent from the second hydrogenated effluent to the liquid portion (119) is reduced to 10°C or more, with WHSV being 0.5–1.5h -1 This range is and the H2 flow is 150-800 Nl H2 / l feed.

[0138] The isomerized effluent (116) from the isomerization reactor (103) is subjected to a separation step (117), where the isomerized effluent (116) is separated into a gaseous fraction (118) and a first isomerized liquid (119). The separation step (117) may be one or more high-pressure or low-pressure separators, for example, which are known to those skilled 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 step (117) may also be distillation, although it is usually beneficial to separate the gaseous fraction from the liquid fraction before distillation.

[0139] As described above, the first isomerized solution contains ≥30 wt% branched hydrocarbons and / or increases the amount of branched hydrocarbons by ≥30 wt% compared to the second hydrogenated solution.

[0140] The isomerized effluent (116) or isomerized liquid (119) may be subjected to a distillation step to produce one or more product fractions. Such fractional distillation is well known in the art.

[0141] In particular, the process of the present invention is beneficial because it has been surprisingly found that certain conditions yield a large fraction of high-quality aviation fuel (see Example 1). Aviation fuel fractions contain C8-C16 hydrocarbons, and in particular, the majority of aviation fuel contains C9-C12 hydrocarbons. Aviation fuel fractions can also be characterized by their distillation range, such as having a distillation range between 150 and 250°C.

[0142] The isomerized liquid can be separated into at least aviation fuel having a cloud point of -25°C or below, for example, -30°C or below, for example, -40°C or below, for example, -47°C or below.

[0143] Figure 1 illustrates the supply of oxygenated hydrocarbon feedstock (104), mixed with hydrogen-enriched gas (120) and a hydrocarbon diluent (126) in the form of product recycling, to the second catalyst zone (105) of a hydrogenation reactor (101) having a first catalyst zone (102) upstream of the second catalyst zone (105). The second hydrogenation effluent (106) is separated in a separator (107) into a gaseous fraction (121) and a second hydrogenation liquid (108). The gaseous fraction (121) can be flushed again at a lower temperature in a separator (122) into a gaseous fraction (123), a water-enriched fraction (125), and a hydrocarbon-enriched fraction (124). The first hydrogenation liquid (108) may be heated (109, 111) and recompressed (110) and mixed with a hydrogen-enriched gas (120) to form a feed (110) for a first catalyst zone (102) which contains therein, where hydrogenation deoxygenation and hydrogenation denitrification are induced to obtain a first hydrogenation effluent from which a product bystream (112) may be taken out. The product bystream (112) is stripped together with hydrogen-enriched gas (120) in a stripper (114) to form a stripped hydrogenation liquid (115), which is mixed with the hydrogen-enriched gas (120) and fed to an isomerization reactor (103) having at least one catalyst zone, where the stripped hydrogenation liquid (115) is isomerized to obtain an isomerized effluent (116), which is separated in a separator (117) into a gaseous fraction (118) and an isomerized liquid (119). This particular arrangement efficiently utilizes fresh hydrogen for polishing in the first catalyst zone to provide a polished hydrocarbon product rich in dissolved hydrogen, where a portion of such product (Figure 1, I (liquid overflow)) and excess hydrogen gas (Figure 1, g) can be used as hydrocarbon diluents and makeup hydrogen in the downstream hydrogenation process in the second catalyst zone, and / or can be removed as a product by-flow (112) between the polishing bed and the hydrogenation bed, and can be isomerized in the isomerization reactor.

[0144] Figure 2 shows the reactor setup for Comparative Example 1 and the comparative examples referenced in Table 7. It is similar to Figure 1, except that the second hydrogenation reactor is omitted. Figure 2 describes feeding an oxygenated hydrocarbon feedstock (204) mixed with a hydrogen-enriched gas (220) and a hydrocarbon diluent (226) into a first hydrogenation reactor (201) having at least one catalyst zone (205). The first hydrogenation effluent (206) is separated in a separator (207) into a gaseous fraction (221) and a first hydrogenation liquid (208). The gaseous fraction (221) can be flushed again at a lower temperature in a separator (222) into a gaseous fraction (223), a water-enriched fraction (225), and a hydrocarbon-enriched fraction (224). The first hydrogenation liquid (208) is stripped together with hydrogen-enriched gas (220) in a stripper (214) to form a stripped hydrogenation liquid (215), which is mixed with the hydrogen-enriched gas (220) and supplied to a first isomerization reactor (203) having at least one catalyst zone, where the stripped hydrogenation liquid (215) is isomerized to obtain a first isomerization effluent (216), which is separated in a separator (217) into a gaseous fraction (218) and a first isomerization liquid (219).

[0145] Figure 3 shows the reactor setup for Comparative Example 2 and the comparative example referenced in Table 7. It is similar to Figure 1, but does not include the separation step between the first and second hydrogenation reactors. Figure 3 describes feeding an oxygenated hydrocarbon feedstock (304), mixed with a hydrogen-enriched gas (320) and a hydrocarbon diluent (326) in the form of product recycling, to a first hydrogenation reactor (301) having at least one catalyst zone (305). The first hydrogenation effluent (306) is mixed with the hydrogen-enriched gas (320) to form a feed for a second hydrogenation reactor (302) having at least one catalyst zone, where hydrodeoxygenation and hydrodenitrification are induced to obtain a second hydrogenation effluent (330), which is separated in a separator (307) into a gaseous fraction (321) and a second hydrogenation liquid (312). The gaseous fraction (321) can be flushed again at a lower temperature in a separator (322) into a gaseous fraction (323), a water-enriched fraction (325), and a hydrocarbon-enriched fraction (324). The second hydrogenation liquid (312) is stripped together with the hydrogen-enriched gas (320) in a stripper (314) to form a stripped hydrogenation liquid (315), which is mixed with the hydrogen-enriched gas (320) and fed into a first isomerization reactor (303) having at least one catalyst zone, where the stripped hydrogenation liquid (315) is isomerized to obtain a first isomerized effluent (316), which is separated in a separator (317) into a gaseous fraction (318) and a first isomerization liquid (319).

[0146] In describing embodiments of the present invention, not all possible combinations and permutations of embodiments are explicitly described. However, the mere fact that certain means are described in different dependent claims or in different embodiments does not imply that combinations of these means cannot be advantageously used. The present invention assumes all possible combinations and permutations of the described embodiments.

[0147] The inventors intend that, in all instances, the terms “comprising,” “comprise,” and “comprises” are optionally replaceable with the terms “consisting of,” “consist of,” and “consists of,” respectively. [Examples]

[0148] Example 1 Low-quality waste derived from animal fat waste, including beef tallow, pork tallow, and chicken tallow, was used as feedstock for a renewable fuel process. This feedstock was purified using bleaching pretreatment before being sent to the hydrogenation process. Table 1 shows the carbon number distribution of the low-quality animal fat feedstock used before pretreatment, as measured by GC according to ISO 15304M.

[0149] [Table 1]

[0150] [Table 2]

[0151] [Table 3]

[0152] The feedstock was pre-treated by bleaching before being used as feedstock for the hydrogenation process, which reduced the amount of nitrogen, calculated as total nitrogen element, to 1000 w-ppm, which became the nitrogen impurity level of the feedstream when it entered the hydrogenation process (see the "Amount of Nitrogen in Feed to HDO" section in Table 4).

[0153] The feedstock treated by hydrogenation contained inorganic and organic nitrogen impurities, with the organic impurities mainly in the form of organic nitrogen compounds such as amides and amines, which were analyzed from the feed. For example, the amounts of metallic impurities such as Ca, Co, Fe, Mg, Mn, Ni, and Zn were below 1 w-ppm, which is the analytical detection precision limit of the specific ICP standard used. Similarly, the amounts of Al and Na impurities were below 2 w-ppm, and the P content was below 1 w-ppm.

[0154] To demonstrate the present invention's ability to utilize various nitrogen content, this pre-treated feedstock was mixed with palm oil having a nitrogen content of 18 w-ppm to obtain six different nitrogen concentrations (25, 75, 150, 300, 500, and 1000 w-ppm) used in runs 1-6 of this embodiment.

[0155] Pre-treated feedstock (fresh feed) containing varying amounts of nitrogen was introduced in six separate runs into a hydrogenation denitrification (HDO) fixed-bed trickle-bed reactor setup as shown in Figure 1. The HDO reaction was carried out in the presence of a catalyst bed (150) containing 45,000 kg of NiMo sulfide supported on an alumina support (fresh catalyst with relative HDO activity compared to fresh HDO catalytic activity), at a pressure of 50 bar, with a feed rate to the HDO reactor of 48,000 kg / h, and 1.1 h for the catalyst bed (150). -1 The total feed rate was WHSV, with an H2 flow of approximately 500 Nl H2 / l feed, and the reaction temperature measured at the HDO reactor inlet was approximately 309°C (T IN ), the temperature at the outlet of the HDO reactor is approximately 340°C (T OUT The process was carried out at 28700m. A fresh hydrogen feed was supplied to the reactor at 28700m. 3 The rate is / h(NTP), and the feed amount of low-quality animal fat waste is 57m 3 The rate was / h. The liquid HDO product was recycled as a diluent (126), and the ratio of recycled product to fresh feed was approximately 6:1.

[0156] The effluent from the HDO reactor was subjected to separation into liquid and gas phases in a high-temperature separator before being supplied to the polishing bed (102) located upstream of the HDO bed. The polishing bed was a fixed bed containing a NiMo sulfide catalyst (a fresh catalyst with relative HDO activity compared to fresh HDO catalytic activity) supported on the same alumina support as the HDO bed, with a catalyst material quantity of 15,000 kg. The polishing bed was subjected to approximately 8.2 hours under a pressure of 50 bar, calculated based on the total liquid feed. -1 It has a supply rate WHSV, and the temperature of the polishing floor inlet (T IN The temperature was approximately 340°C, which is 31°C higher than the HDO inlet temperature. The amount of hydrogen used was approximately 25 vol-% of the amount of hydrogen used in the HDO reactor catalyst bed.

[0157] Table 4 shows the results of a test run using the setup shown in Figure 1, as described above, where a combined HDO reactor and polishing bed were used, and where gaseous by-products containing nitrogen compounds were removed between the two beds. As is evident from Table 4, despite the very high nitrogen content of the fresh feed, the nitrogen content after the polishing step can be kept low. Low nitrogen content is desirable for the product for various reasons, in particular, because low nitrogen content affects the isomerization reaction, thereby resulting in better cold flow characteristics under the same isomerization conditions compared to a product with a high nitrogen content before isomerization (data not shown).

[0158] The nitrogen content can be reduced to ≤0.4 w-ppm by changing process conditions, particularly by increasing the processing temperature of the polishing bed. The final nitrogen impurity was ≤0.3 w-ppm in all runs (1-6). Increasing the HDO bed temperature typically leads to uncontrolled reactions that cause degradation of the low-temperature properties of the final isomerization product. After hydrogenation denitrification and polishing, the final liquid paraffin effluent was hydrogen-isomerized in the isomerization reactor. Isomerization was carried out in a fixed-bed trickle-bed reactor at a pressure of 40 bar in the presence of a Pt-SAPO catalyst for 1.5 hours. -1The reaction was carried out in WHSV at a reaction temperature of 328°C. The hydrogen / feed ratio was 300 normal liters of H2 per liter of feed. The very low nitrogen content in all experiments gave the product excellent low-temperature properties. After separation by isomerization and distillation, an aviation fuel cut was obtained with a T10(°C) cutoff temperature of 185–205°C, a T90(°C) cutoff temperature of 270–295°C, and a final boiling point (°C) of 275–300°C, which meets ASTM D7566 (2016), Annex A2 specification and yields 772 kg / m³ 3 It had a density of less than -40°C (measured according to ASTM 4052 (2018)) and a freezing point (measured according to IP529) below -40°C. The aviation fuel component obtained in excellent yield of approximately 60 wt-% further had a turbidity point below -30°C (measured according to ASTM D5771 (2017)).

[0159] [Table 4]

[0160] Comparative Example 1 As an alternative for efficiently removing undesirable oxygen and nitrogen impurities, the reactor setup shown in Figure 2 was tested. In the setup in Figure 2, the same feed composition as in Example 1 was applied, and substantially the same operating conditions (temperature, pressure, catalyst, etc.) as those used in Example 1 were used, except that this reactor setup lacked the polishing bed (102) downstream of the HDO reactor. In this example, rather, the entire amount of fresh catalyst (60,000 kg) was located in a single HDO reactor. The HDO reaction was carried out at a pressure of 50 bar, a feed rate to the HDO reactor of 48,000 kg / h, and 0.8 h -1 The total feed rate was WHSV, with an H2 flow of approximately 590 Nl H2 / l feed, and the reaction temperature measured at the HDO reactor inlet was approximately 308°C (T IN ), the temperature at the outlet of the HDO reactor is approximately 340°C (T OUT The process was carried out at 33400m. Fresh hydrogen feed to the reactor was 33400m.3 The rate is / h(NTP), and the feed amount of low-quality animal fat waste is 57m 3 The rate was / h. The liquid HDO product was recycled as a diluent, and the ratio of recycled product to fresh feed was approximately 6:1.

[0161] Table 5 shows the results of a run in a single HDO reactor as shown in Figure 2, where gaseous byproducts containing nitrogen-containing compounds were removed after the HDO reactor and before the liquid paraffin effluent was introduced into the isomerization step.

[0162] As can be seen from Table 5, the nitrogen content before the isomerization reactor in all runs (7-12) was higher compared to the nitrogen content in Example 1. In Comparative Example 1, the same amount of catalyst was used as in Example 1, but in this example it was contained within a single reactor. This comparison shows that a single reactor cannot remove nitrogen in the same efficient manner as when the catalyst amount is divided into two separate reactors and the gas phase is removed between these two reactors.

[0163] The increase in nitrogen content in the feed inevitably led to an increase in nitrogen in the final liquid paraffin effluent stream for isomerization, resulting in a decrease in the low-temperature properties and yield of the aviation fuel component recovered from fractional distillation after isomerization. In run 12, where the initial nitrogen content was 1000 ppm, a turbidity of approximately -10°C was obtained, along with an aviation fuel yield of 5 wt-%.

[0164] [Table 5]

[0165] Comparative Example 2 The reaction setup shown in Figure 3 is otherwise similar to Example 1, except that two HDO reactors are used in series, and there is no gas removal after the first HDO reactor before the feed (306) is introduced into the second HDO reactor (302) downstream of the first HDO reactor (301). A catalyst bed similar to the polishing bed in Figure 1 was installed inside the second HDO reactor (302). The liquid paraffin effluent (306) from the first HDO reactor was introduced into the second HDO reactor directly, i.e., without removing gaseous by-products containing nitrogen-containing compounds after the first HDO reactor before introducing the liquid paraffin effluent into the second HDO reactor. The final liquid paraffin effluent stream (312) obtained after the second HDO reactor (302) was led to a stripper (314) to remove gaseous impurities, and then to an isomerization reactor. The catalyst and reaction conditions were the same as in Example 1.

[0166] This reactor configuration was similar to the prior art reactor setup described in Patent Document 1.

[0167] As can be seen from Table 6, the nitrogen content of all orbs (13-18) was significantly higher compared to the nitrogen content of Example 1.

[0168] The setup shown in Figure 3 was found to reduce nitrogen impurities at lower nitrogen content in the initial feed, e.g., around 25 ppm or less. However, when the nitrogen content in the fresh feed was increased to 150 wppm or more, the residual nitrogen after HDO and polishing increased to 0.8 ppm or more. The increase in nitrogen content in isomerization resulted in reduced low-temperature properties and yield of the aviation fuel component recovered from fractional distillation after isomerization. In run 18, where the initial nitrogen content was 1000 ppm, a turbidity of approximately -15°C was obtained, along with an aviation fuel yield of 10 wt-%.

[0169] [Table 6]

Claims

1. A process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities of 10 wppm or more as measured as elemental nitrogen, A hydrogenation reactor (101) comprising a first catalyst zone (102) positioned above a second catalyst zone (105), wherein a hydrogenation inlet flow containing an oxygenated hydrocarbon feedstock (104), a hydrogen enrichment gas (120), and optionally a product recycling diluent (108, 126) is introduced into the second catalyst zone (105) at an inlet between the first catalyst zone (102) and the second catalyst zone (105), and it is introduced into the second catalyst zone (105) from the first catalyst zone. A portion of the hydrogenation effluent of the first hydrogenation effluent is mixed with a portion of the first hydrogenation effluent, the portion of the first hydrogenation effluent contains liquid hydrocarbons containing dissolved hydrogen, the second catalyst zone is operated at a temperature and pressure that causes at least hydrogen deoxygenation and hydrogen denitrification to such an extent that the second hydrogenation effluent (106) from the second catalyst zone (105) of the hydrogenation reactor contains mainly hydrocarbons, and thereafter the hydrogenation reactor (101) converts the oxygenated hydrocarbon feedstock into hydrocarbons ≥95%: The second hydrogenation effluent from the second catalyst zone of the hydrogenation reactor is separated into a gaseous fraction (121) and a second hydrogenation liquid (108), at least a portion of which is subjected to a separation step (107) in which the second hydrogenation liquid (108) contains ≥95 wt% hydrocarbons and >1 wppm nitrogen; At least a portion of the second hydrogenation liquid (108) and the hydrogen enrichment gas (120) are introduced into the first catalyst zone (102) in the hydrogenation reactor (101) at an inlet temperature higher than the inlet temperature in the second catalyst zone of the hydrogenation reactor, and at a pressure that causes hydrogenation deoxygenation and hydrogenation denitrification; A product bystream (112) containing a portion of the first hydrogenation effluent from the first catalyst zone (102) is withdrawn between the first catalyst zone and the second catalyst zone, the product bystream (112) comprising liquid and gaseous components, and the liquid component of the product bystream comprising ≥99 wt% hydrocarbons and ≤1 wppm nitrogen, as measured as elemental nitrogen; Optionally, the process includes isomerizing the product bystream in an isomerization reactor (103) comprising at least one catalyst zone, where the product bystream (112) and a hydrogen-enriched gas (120) containing nitrogen measured as ≤1 ppm (mol / mol) are introduced into the catalyst zone at an inlet temperature and pressure that causes at least hydrogen isomerization to produce an isomerization effluent (116); The isomerized effluent from the isomerization reactor is subjected to a separation step (117), where the isomerized effluent (116) is separated into a gaseous fraction (118) and an isomerized liquid (119), where the isomerized liquid contains ≥30 wt% branched hydrocarbons and / or an increase of ≥30 wt% branched hydrocarbons compared to the second hydrogenated liquid (108); Here, a portion of the first hydrogenation effluent from the first catalyst zone (102) heats the hydrogenation inlet flow; and The temperature and pressure at the inlet of the second catalyst zone (105) are 200 to 400°C and 10 to 150 bar, and The temperature and pressure at the inlet of the first catalyst zone (102) are 250 to 450°C and 10 to 150 bar. This includes, A process in which hydrocarbon diluents and fresh oxygenated hydrocarbon feedstock are not introduced into the first catalyst zone (102) of the hydrogenation reactor.

2. The product bystream is subjected to a stripping step (114), where the product bystream (112) is stripped with a stripping gas (H) such that the stripped product bystream (115) has a nitrogen content of ≤0.4 wppm as measured as nitrogen element, and has a lower nitrogen content compared to the product bystream (112). 2 ) is stripped using; A step of isomerizing the stripped product bystream (115) in a first isomerization reactor (103) including at least one catalyst zone, wherein the stripped product bystream (115) and a hydrogen-enriched gas (120) having ≤1 ppm (mol / mol) of nitrogen as measured as elemental nitrogen are introduced into the catalyst zone at a temperature and pressure that causes at least hydrogenation denitrification to produce a first isomerization effluent (116); The isomerized effluent from the first isomerization reactor (103) is subjected to a separation step (117), where the isomerized effluent is separated into a gaseous fraction and an isomerized liquid, the isomerized liquid containing ≥30 wt% branched hydrocarbons. The process according to claim 1.

3. The process according to claim 1 or 2, wherein the isomerized liquid is separated into at least aviation fuel having a freezing point of -40°C or lower.

4. The process according to any one of claims 1 to 3, wherein cooling is applied during the separation step of the second hydrogenation effluent (106) to such an extent that the second hydrogenation liquid (108) is at a temperature lower than the temperature of the inlet to the first catalyst zone of the hydrogenation reactor.

5. The process according to any one of claims 1 to 4, wherein the degree of hydrogenation deoxygenation and hydrogenation denitrification in the second catalyst zone (105) is controlled in such a manner that the temperature rise between the reactor inlet and the reactor outlet in the first catalyst zone (102) does not exceed 10°C.

6. The process according to any one of claims 1 to 5, wherein the second catalyst zone (105) in the hydrogenation reactor (101) has lower hydrogenation deoxygenation activity than the first catalyst zone (102) in the hydrogenation reactor (101).

7. The process according to any one of claims 1 to 6, wherein the hydrogen enrichment gas (120) used in the first catalyst zone (102) contains nitrogen impurities measured as nitrogen element in an amount of ≤ 5 wppm.

8. The process according to any one of claims 1 to 7, wherein the temperature and pressure at the inlet of the second catalyst zone (105) are 250 to 380°C and 20 to 120 bar.

9. The process according to any one of claims 1 to 8, wherein the second catalyst zone of the hydrogenation reactor comprises one or more catalysts selected from metal hydrides supported on a carrier.

10. The hydrogenation reactor (101) operates for 0.5 to 3 hours. -1 In the WHSV range, and 350-900 Nl H 2 / l feed H 2 A process according to any one of claims 1 to 9, operated in a flow.

11. The process according to any one of claims 1 to 10, wherein the temperature and pressure at the inlet of the first catalyst zone (102) are 300 to 430°C and 20 to 120 bar.

12. The process according to any one of claims 1 to 11, wherein the first catalyst zone of the hydrogenation reactor comprises one or more catalysts selected from metal hydrides supported on a carrier.

13. The process according to any one of claims 1 to 12, wherein the temperature and pressure at the inlet of the isomerization reactor (103) are 280 to 370°C and 20 to 50 bar.

14. The process according to any one of claims 1 to 13, wherein the catalyst zone of the isomerization reactor comprises one or more catalysts comprising a group VIII metal supported on a carrier, the carrier being selected from silica, alumina, clay, titanium oxide, boron oxide, and zirconia, which may be used individually or in mixtures.

15. The process according to claim 14, wherein the one or more catalysts further comprises molecular sieves.

16. The isomerization reactor (103) operates for 0.5 to 1 hour. -1 In the WHSV range, and 300-500 Nl H 2 / l feed H 2 A process according to any one of claims 1 to 15, operated in a flow.

17. The process according to any one of claims 1 to 16, wherein the isomerizing solution has an isoparaffin-to-n-paraffin ratio of 5 to 30 or 15 to 30.

18. The process according to any one of claims 1 to 17, wherein the oxygenated hydrocarbon feedstock contains 300 wppm or more nitrogen impurities as measured as nitrogen element.

19. The process according to any one of claims 1 to 18, wherein the hydrogenation treatment inlet flow contains 100 to 500 wppm of nitrogen impurities.

20. The process according to any one of claims 1 to 19, wherein the second hydrogenation effluent (106) from the second catalyst zone contains 100 to 500 wppm or more of nitrogen impurities.

21. The process according to any one of claims 1 to 20, wherein the product bystream (112) containing a portion of the first hydrogenation effluent from the first catalyst zone (102) taken out between the first catalyst zone and the second catalyst zone comprises a liquid component and a gaseous component, and the liquid component of the product bystream comprises ≥99 wt% hydrocarbons and nitrogen measured as ≤0.3 wppm.

22. The process according to any one of claims 1 to 21, wherein the oxygenated hydrocarbon feedstock may contain 40 wt% or more of a fatty acid or fatty acid ester.

23. The process according to any one of claims 1 to 22, wherein the oxygenated hydrocarbon feedstock may be selected from plant oils and animal fats.

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