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 reactor and further hydrotreating in a second hydrotreating reactor, where a vapor phase is removed between the two reactors. The specific process setup effectively removes nitrogen impurities from the resulting hydrocarbon product, resulting in an improved cloud point after isomerization.

Description

[Technical Field]

[0001] The present invention relates to a process for producing hydrocarbons from oxygenated hydrocarbon feedstock having nitrogen impurities of 500 wppm or more as measured as elemental nitrogen, and more particularly to improving the quality and quantity of aviation fuel obtained therefrom. [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 feedstock, and it is a well-known component of fossil and renewable oils. Average nitrogen content of 940 w-ppm and high levels up to 7500 w-ppm have been reported in crude oil (Non-Patent Literature 1). It is also not uncommon for animal 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 straightforward. However, in the case of animal fats, most nitrogen compounds are oil-soluble and are 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 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 animal fat with a nitrogen content of about 1 wt% is hydrogenated and isomerized under the conditions described in Patent Document 1, 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 stage 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] In order to remove as much nitrogen as possible, there is also a possibility of further purifying the feed before hydrogenation. However, although the purification method 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.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Non-Patent Documents

[0013]

Non-Patent Document 1

Summary of the Invention

[0014] 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 hydrotreated product obtained from an oxygenated hydrocarbon feed containing nitrogen impurities exceeding a general range of 1 to 100 ppm, particularly a process in which the improved quality includes at least a low amount of nitrogen impurities in the product.

[0015] To solve this problem, the present invention provides a process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock (such as animal fat) having nitrogen impurities measured as nitrogen element and being 150 wppm or more, for example 300 ppm or 500 wppm or more. Here, the process includes two hydrotreating reactors (101, 102). The effluent from the first hydrotreating reactor is purified, and the purified effluent from the first hydrotreating reactor (108) is hydrotreated at a higher temperature in the second hydrotreating reactor (102). And the feed to the second hydrotreating reactor is not mixed with the oxygenated feedstock.

[0016] Specifically, the present invention provides a process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities measured as nitrogen element and being 300 wppm to 3000 wppm or more, a first hydrotreating reactor (101) including at least one catalyst zone (105), where a hydrotreating inlet stream including an oxygenated hydrocarbon feedstock (104) and optionally a hydrocarbon diluent (126) is introduced into the catalyst zone together with a hydrogen-rich gas (120) at an inlet temperature and pressure that cause at least hydrodeoxygenation and hydrodenitrogenation until the first hydrotreating effluent (106) from the first hydrotreating reactor mainly contains hydrocarbons and the oxygenated hydrocarbon feedstock is converted to ≧95% hydrocarbons, where the first hydrotreating effluent (106) from the first hydrotreating reactor is subjected to a separation stage (107) in which at least a part of the first hydrotreating effluent (106) is separated into a gaseous fraction (121) and a first hydrotreating liquid (108), and the first hydrotreating liquid contains ≧95 wt% hydrocarbons and >1 wppm nitrogen, At least a portion of the first hydrogenation liquid (108) and the hydrogen enrichment gas (120) are introduced into a second hydrogenation reactor (102) including at least one catalyst zone at an inlet temperature (higher than the inlet temperature in the first hydrogenation reactor) and pressure that cause hydrogenation deoxygenation and hydrogenation denitrification, wherein the first hydrogenation liquid is not mixed with a feed having an oxygen content higher than the oxygen content of the first hydrogenation liquid, and the first hydrogenation liquid is not mixed with a feed having a nitrogen content higher than the nitrogen content of the first hydrogenation liquid. The second hydrogenation effluent (130) from the second hydrogenation reactor (102) is subjected to one or more separation steps (111 and / or 114), where the second hydrogenation effluent (130) is separated into a gaseous fraction (113) and the second hydrogenation liquid (112) and / or stripped hydrogenation liquid (115), the second hydrogenation liquid (112) and / or stripped hydrogenation liquid (115) containing ≥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). Regarding the process.

[0017] 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 of a first hydrogenation reactor by separation into a gas phase and a liquid phase, and the liquid phase therefrom is then hydrogenated in a second hydrogenation reactor, 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, oxygenated hydrocarbons containing much greater amounts of nitrogen than normally present can be efficiently hydrogenated using only two hydrogenation reactors, each containing at least one catalyst zone. The second hydrogenation effluent is then separated into a gas phase and a second hydrogenation liquid stream, where the separation may be a stripping step or precede a stripping step, and the second hydrogenation liquid stream may be stripped using a stripping gas, such as hydrogen, to reduce the nitrogen content of the stripped hydrogenation liquid to 0.3 wppm or less.

[0018] The second hydrogenation treatment liquid (112) can be used as a product of the process or recycled into the process. A second hydrogenation liquor may also be isomerized in a first isomerization reactor (103) comprising at least one catalyst zone, where the second hydrogenation liquor 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 a first isomerization effluent (116), the first isomerization effluent (116) from the first isomerization reactor (103) is subjected to a separation step (117), where the first isomerization effluent (116) is separated into a gaseous fraction (118) and a first 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 second hydrogenation liquor.

[0019] For example, the second hydrogenation liquid (116) or second hydrogenation effluent (130) is subjected to a stripping step (114), where the second hydrogenation liquid or second hydrogenation effluent is stripped with a stripping gas (120) such that the stripped hydrogenation liquid (115) has a nitrogen content of ≤0.4 wppm as measured as elemental nitrogen, and a lower nitrogen content compared to the second hydrogenation liquid (112), for example, ≤0.4 wppm as measured as elemental nitrogen; this stripped hydrogenation liquid (115) is then subjected to a first isomerization reactor including at least one catalyst zone ( In 103), the product may be subjected to an isomerization step, where the stripped hydrogenated liquid (115) and a hydrogen-enriched gas (120) having ≤1 ppm (mol / mol) of nitrogen as measured as elemental nitrogen are introduced into a catalyst zone at a temperature and pressure that causes at least hydrogen denitrification to produce a first isomerized effluent (116); where the first isomerized effluent (116) from the first isomerization reactor (103) is subjected to a separation step (117), where the first isomerized effluent (116) is separated into a gaseous fraction (118) and a first isomerized liquid (119), the first isomerized liquid containing ≥30 wt% branched hydrocarbons.

[0020] The first isomerized liquid (119) can be separated into at least aviation fuel having a cloud point of -40°C or lower, for example, -47°C or lower.

[0021] Cooling may be applied during the separation step of the first hydrogenation liquid (106) to such an extent that the first hydrogenation liquid (108) is at a temperature lower than the temperature of the inlet of the first catalyst zone of the first hydrogenation reactor. For example, the first hydrogenation liquid (108) is at a temperature at least 50°C lower than the temperature of the inlet of the first catalyst zone of the first hydrogenation reactor.

[0022] The diluent is not necessary to control the exothermic characteristics of the hydrogenation reaction in the second hydrogenation reactor. Therefore, the hydrocarbon diluent does not need to be present in the second hydrogenation reactor; in other words, the hydrocarbon diluent may not be introduced into the second hydrogenation reactor (102) in some cases.

[0023] The degree of hydrogenation deoxygenation and hydrogenation denitrification in the first hydrogenation reactor can be controlled in the second hydrogenation reactor in such a manner that the temperature rise between the reactor inlet and the reactor outlet does not exceed 10°C.

[0024] The catalyst zone or multiple catalyst zones in the first hydrogenation reactor (101) may have lower hydrogenation deoxygenation activity than the catalyst zone or multiple catalyst zones in the second hydrogenation reactor (102), or the catalyst zone or multiple catalyst zones in the second hydrogenation reactor (102) may have higher hydrogenation deoxygenation activity than the catalyst zone or multiple catalyst zones in the first hydrogenation reactor (101).

[0025] The hydrogen-enriched gas (120) used in the second hydrogenation reactor (102) may contain nitrogen impurities of ≤5 wppm, as measured for elemental nitrogen.

[0026] The temperature and pressure at the inlet of the first hydrogenation reactor (101) 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.

[0027] The first hydrogenation reactor (101) may comprise at least three catalyst zones or up to three catalyst zones, for example, one, two, or three catalyst zones.

[0028] The catalyst zone of the first 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, and CoNiMo supported on a support, such as an alumina support.

[0029] The first hydrogenation reactor (101) is used 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.

[0030] The temperature and pressure at the inlet of the second hydrogenation reactor (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.

[0031] The second hydrogenation reactor (102) may have a single catalyst zone.

[0032] The catalyst zone of the second 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, and CoNiMo supported on a support such as an alumina support.

[0033] The second hydrogenation reactor (102) lasts 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.

[0034] The temperature and pressure at the inlet of the first isomerization reactor (103) can be 280-370°C and 0-50 bar, respectively.

[0035] 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.

[0036] Furthermore, one or more catalysts may further contain molecular sieves, such as zeolites.

[0037] 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.

[0038] The first isomerized solution can be isomerized to such an extent that the ratio of isoparaffin to n-paraffin is greater than 1, for example, 1 to 2.5.

[0039] The hydrogenation treatment inlet stream may contain nitrogen impurities at concentrations of 100-500 wppm or higher.

[0040] The first hydrogenation effluent (106) from the first hydrogenation reactor may contain nitrogen impurities at concentrations of 100-500 wppm or higher. [Brief explanation of the drawing]

[0041] [Figure 1] Figure 1 shows a process scheme according to the present invention, comprising a first hydrogenation reactor (101), a second hydrogenation reactor (102), and a third hydrogenation 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]

[0042] 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 such selected terms, and each specific term is understood to include all technical equivalents that operate in a similar manner to achieve a similar purpose. When nitrogen content is referred to, unless otherwise specified, it is intended to be nitrogen content measured as elemental nitrogen.

[0043] The present invention relates to a process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities measured as elemental nitrogen at 500 wppm or more, A first hydrogenation reactor (101) comprising at least one catalyst zone (105), wherein a hydrogenation inlet stream comprising an oxygenated hydrocarbon feedstock (104) and optionally a hydrocarbon diluent (126) is introduced into the catalyst zone together with a hydrogen-enriched gas (120) at an inlet temperature and pressure that causes at least hydrogen deoxygenation and hydrogen denitrification to such an extent that the first hydrogenation effluent (106) from the first hydrogenation reactor mainly consists of hydrocarbons, the hydrogenation inlet stream contains 100 wppm or more of nitrogen impurities, and the oxygenated hydrocarbon feedstock is converted to ≥95% hydrocarbons, wherein The first hydrogenation effluent (106) from the first hydrogenation reactor is separated into a gaseous fraction (121) and a first hydrogenation liquid (108), at least a portion of which is subjected to a separation step (107) in which the first hydrogenation liquid contains ≥95 wt% hydrocarbons and >1 wppm nitrogen. At least a portion of the first hydrogenation liquid (108) and the hydrogen enrichment gas (120) are introduced into a second hydrogenation reactor (102) including at least one catalyst zone at an inlet temperature (higher than the inlet temperature in the first hydrogenation reactor) and pressure that cause hydrogenation deoxygenation and hydrogenation denitrification, wherein the first hydrogenation liquid is not mixed with a feed having an oxygen content higher than the oxygen content of the first hydrogenation liquid, and the first hydrogenation liquid is not mixed with a feed having a nitrogen content higher than the nitrogen content of the first hydrogenation liquid. The second hydrogenation effluent (130) from the second hydrogenation reactor (102) is subjected to one or more separation steps (111 and / or 114), where the second hydrogenation effluent (130) is separated into a gaseous fraction (113) and the second hydrogenation liquid (112) and / or stripped hydrogenation liquid (115), the second hydrogenation liquid (112) and / or stripped hydrogenation liquid (115) containing ≥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). Regarding the process.

[0044] 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 of a first hydrogenation reactor by separation into a gas phase and a liquid phase, and the liquid phase therefrom is then hydrogenated in a second hydrogenation reactor, 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, oxygenated hydrocarbons containing much greater amounts of nitrogen than normally present can be efficiently hydrogenated using only two hydrogenation reactors, each containing at least one catalyst zone. The second hydrogenation effluent is then separated into a gas phase and a second hydrogenation liquid stream, where the separation may be a stripping step or a step prior to the stripping step, and the second hydrogenation liquid stream may be stripped with a stripping gas, such as hydrogen, to reduce the nitrogen content of the stripped hydrogenation liquid to 0.3 wppm or less.

[0045] 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 typically 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 (FAE). Therefore, oxygenated hydrocarbon feedstocks from renewable sources may contain 25 wt% or more fatty acids or fatty acid esters.

[0046] For example, the renewable nature of carbon-containing compositions such as feedstocks and products is due to the feedstock's... 14The C isotope content can be determined by comparing it with the C isotope content in the atmosphere in 1950. 14 The C isotope content can be used as proof of the renewable origin of the feedstock or product. The carbon atoms of renewable materials contain more unstable radiocarbon ( 14 C) atoms compared to the carbon atoms of fossil origin. Therefore, 14 by analyzing the ratio of the 12 C and 14 C isotopes, it is possible to distinguish carbon compounds from biological sources and carbon compounds from fossil sources. Therefore, a specific ratio of these isotopes can be used to identify renewable carbon compounds and distinguish them from non-renewable, i.e., fossil carbon compounds. The isotope ratio does not change during the course of a chemical reaction. An example of a suitable method for analyzing the carbon content from biological sources is ASTM D6866 (2020). An example of how to apply ASTM D6866 to determine the renewable content in fuels is shown in the paper by Dijs et al., Radiocarbon, 48(3), 2006, pp 315-323. For the purposes of the present invention, a carbon-containing material, such as a feedstock or product, for example, is considered to have a renewable origin if it is measured using ASTM D6866 and contains 90% or more of the current standard carbon, such as 100% of the current standard carbon.

[0047] Many vegetable oils and animal fats may contain typical amounts of nitrogen impurities, such as between 1 and 100 ppm, and these may 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 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, such as 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, such as 600 to 1400 wppm. The oxygenated hydrocarbon feedstock may, if preferred, consist of a mixture of oxygenated hydrocarbons from various sources. 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.

[0048] 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.

[0049] The process involves flowing a hydrogenation inlet stream into a first hydrogenation reactor (101) which includes at least one catalyst zone (105). The hydrogenation inlet stream comprises an oxygenated hydrocarbon feedstock (104), which may be selected from the aforementioned nitrogen-containing plant oils, animal fats, or mixtures thereof, such as 300 wppm or more of nitrogen, or 500–1500 wppm. The hydrogenation inlet stream may optionally contain a hydrocarbon diluent (126). The hydrocarbon diluent may be product recycled (126) or hydrocarbons of fossil or renewable origin. Typically, to control the exothermic properties of the hydrogenation reaction, product recycled will be added to the oxygenated hydrocarbon feedstock. If a hydrocarbon diluent is added, it will typically be added in amounts ranging from 1:1 to 4:1 (total hydrocarbon diluent:total oxygenated 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 can also be used alone or in mixtures with other hydrocarbon diluents as part of a hydrocarbon diluent, such as a product recycling product. For example, a hydrocarbon diluent may be a mixture of product recycling and fossil hydrocarbons.

[0050] Product recycling is advantageous for use because it typically involves dissolved hydrogen associated with hydrogenation reactions that depend on hydrogen dissolved in the liquid phase.

[0051] The hydrogenation inlet stream may have nitrogen impurities of 100 wppm or more, for example, 100-500 wppm, and / or the first hydrogenation effluent (106) from the first hydrogenation reactor may have nitrogen impurities of 100-500 wppm or more. A hydrogenation inlet stream having nitrogen impurities of less than 100 wppm may 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 feedstock having 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 treated by the hydrogenation process. Alternatively or additionally, the nitrogen content may also be measured in the first hydrogenation effluent (106) from the first hydrogenation reactor, which may have nitrogen impurities of 100-500 wppm or more.

[0052] Regarding the maximum amount of nitrogen impurities that may be present: There may be limitations on how many nitrogen impurities, or how high a degree of impurity, can realistically be removed. Therefore, the first hydrogenation effluent (106) from the hydrogenation inlet stream and / or the first hydrogenation reactor may have nitrogen impurities up to 500 wppm, i.e., the first hydrogenation effluent (106) from the hydrogenation inlet stream and / or the first hydrogenation reactor may have nitrogen impurities between 100 and 500 wppm.

[0053] The hydrogenation inlet flow is introduced along with a hydrogen-enriched gas (120) into a first hydrogenation reactor (101) which has at least one catalyst zone (105).

[0054] The hydrogen-enriched gas (120) is required in the first hydrogenation reactor (101), i.e., to carry out the hydrogenation deoxygenation (HDO) and hydrogenation denitrification (HDN) reactions. The hydrogen-enriched gas may be excess hydrogen from the process (123, 131, 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 hydrogenation reactor is preferably not as critical as the purity of the hydrogen-enriched gas used in the second hydrogenation reactor (102), the hydrogen-enriched gas used for stripping before the isomerization reactor (114), or the hydrogen-enriched gas used in the isomerization reactor (103), preferably containing no reactive nitrogen such as ammonia, for example, and containing less than 0.3 wppm of nitrogen as measured as elemental nitrogen. Typically, the hydrogen enrichment gas used for the first hydrogenation reactor 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.

[0055] The hydrogenation reactor (101) 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 hydrogenation inlet flow, 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.

[0056] The first hydrogenation reactor (101) includes at least one catalyst zone (105). 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.

[0057] The first hydrogenation reactor (101) may comprise at least three catalyst zones or up to three catalyst zones, for example, one, two, or three catalyst zones.

[0058] The hydrogenation inlet flow, along with the hydrogen-enriched gas (120), is introduced into a first hydrogenation reactor (101) which includes at least one catalyst zone (105).

[0059] The hydrogenation inlet flow, along with the hydrogen-enriched gas (120), is introduced into the catalyst zone at an inlet temperature and pressure that causes at least hydrogenated deoxygenation and hydrogenated denitrification to such an extent that the first hydrogenation effluent (106) from the first hydrogenation reactor contains mainly hydrocarbons.

[0060] There are many different inlet temperature and pressure combinations that will produce HDO and HDN to the extent that oxygen is removed from the oxygenated hydrocarbon, thereby producing water as a byproduct, and nitrogen impurities are removed from the oxygenated hydrocarbon, thereby producing a product mainly consisting of ammonia and hydrocarbons as byproducts.

[0061] For example, the temperature and pressure at the inlet of the first hydrogenation reactor (101) 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.

[0062] It is common practice for those skilled in the art to select various combinations of temperature and pressure that cause at least hydrogenated deoxygenation and hydrogenated denitrification to such an extent that the first hydrogenated effluent (106) from the first hydrogenated reactor 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.

[0063] Just as a person skilled in the art can select various combinations of temperature and pressure, a person skilled in the art can also select one or more catalysts suitable for one or more catalyst zones of the first hydrogenation reactor.

[0064] For example, the catalyst zone of the first 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.

[0065] The first hydrogenation reactor (101) is used for 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.

[0066] More general reaction conditions for the first hydrogenation step may include a trickle bed reactor as the first hydrogenation reactor, comprising a catalyst zone, the catalyst zone comprising a supported hydrogenation catalyst containing molybdenum, where the hydrogenation is carried out in the presence of hydrogen at a temperature of 200-400°C and a pressure between 10-150 bar, where WHSV is 0.5-3h -1 This ranges from 300 to 2100 Nl H2 / l, and represents an H2 flow with a feed of 300 to 2100 Nl H2 / l.

[0067] The first hydrogenation step produces a first 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. In the process of the present invention, far more ammonia (NH3) will be produced than during the hydrogenation of a typical feed containing a typical amount of nitrogen, for example 1 to 100 ppm, such as palm oil which may contain 23 ppm of nitrogen. Surprisingly, the inventors found that when the hydrogenation effluent is subjected to a second hydrogenation step with added makeup hydrogen, the increased amount of ammonia in the hydrogenation effluent causes nitrogen reuptake. In other words, the inventors confirmed that the second hydrogenation effluent from such a second hydrogenation process still contained 2–5 ppm of nitrogen even after stripping with hydrogen gas. That is, even if there was a 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 second hydrogenation process was carried out at a higher temperature, based on the specific expectation that it would perform more advanced HDO and HDN hydrogenation, thereby removing less oxygen and nitrogen from the first hydrogenation effluent. Furthermore, even if ammonia reacted under the conditions of the second hydrogenation process to produce amines or amides, and even if there was a theoretical possibility that such nitrogen compounds would be produced, it was expected that the hydrocarbons already produced 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 discovered that nitrogen compounds that did not disappear under the hydrogenation conditions of the second hydrogenation reactor were regenerated. These compounds were secondary and tertiary amides.

[0068] 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 Example 1, the absence of a separation step between the first and second hydrogenation reactors when hydrogenating an oxygenated hydrocarbon feedstock results in a higher nitrogen content being supplied to the isomerization reactor, which in turn leads to a decrease in the yield of aviation fuel cut with a cloud point below -40°C.

[0069] It was an unexpected discovery that ammonia in the first hydrogenation effluent 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, thereby subjecting the first hydrogenation effluent from the first hydrogenation reactor to a separation step (107), where at least a portion of the first hydrogenation effluent (106) is separated into a gaseous fraction (121) and the first hydrogenation liquid (108).

[0070] The separation step (107) may be one or more high-pressure or low-pressure separators known in the art to be capable of separating the first hydrogenation effluent (106) into a gaseous fraction (121) and the first hydrogenation liquid (108). Hydrogen stripping may be used for separation (not shown). 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 second hydrogenation step. It may also be beneficial if the separated first hydrogenation liquid is used for product recycling to dilute the oxygenated hydrocarbon feedstock.

[0071] 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 first hydrogenation effluent (106) to such an extent that the first hydrogenation effluent (108) has a temperature lower than the inlet temperature of the first catalyst zone of the first hydrogenation reactor. For example, the first hydrogenation effluent (108) has a temperature at least 50°C lower than the inlet temperature of the first catalyst zone of the first hydrogenation reactor, for example, at least 100°C lower than the inlet temperature of the first hydrogenation reactor. The low-temperature separation of the first hydrogenation effluent may be carried out at a temperature between 120 and 200°C, for example.

[0072] The entirety of the first hydrogenation effluent (106), or at least a portion of the first hydrogenation effluent (106), can be separated. For example, the first hydrogenation effluent may be split into two streams, where the first stream is separated into the first hydrogenation liquid and gaseous fraction as described above, and the second stream is used as a hydrocarbon diluent without separation. The second stream contains hydrocarbons, as well as excess hydrogen and all gaseous impurities, including ammonia, which will be reintroduced into the first hydrogenation reactor.

[0073] The entire amount of the first hydrogenation effluent (106) can be separated in order to avoid the accumulation of ammonia in the first hydrogenation reactor, which may react with oxygenated hydrocarbons to form further nitrogen compounds and thus may be present in the first hydrogenation effluent, or to avoid the addition of further amounts of ammonia to the first hydrogenation reactor (if the first hydrogenation effluent is used for product recycling).

[0074] In the separation step (107), the first hydrogenation effluent (106) is separated into a gaseous fraction (121) and a first 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 first 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 first 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 first hydrogenation liquid (108) contains ≤99 wt% hydrocarbons, i.e., to such an extent that the first hydrogenation liquid (108) contains 95-99 wt% hydrocarbons.

[0075] The remaining components of the first hydrogenation solution would be heteroatom-containing hydrocarbons, such as oxygenated hydrocarbons or nitrogen-containing hydrocarbons. Because the initial nitrogen impurities are very high, it is assumed that some nitrogen still remains 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.

[0076] For example, a first hydrogenation solution (108) containing 5 to 100 wppm of nitrogen impurities, or at least a portion of the first hydrogenation solution (108), is introduced into a second hydrogenation reactor (102) together with a hydrogen enrichment gas (120).

[0077] The hydrogen-enriched gas (120) is required not only in the first hydrogenation reactor (101) but also in the second hydrogenation reactor (102), as described above, to carry out the hydrogenation deoxygenation (HDO) and hydrogenation denitrification (HDN) reactions. The hydrogen-enriched gas may be excess hydrogen from the process (123, 131, 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 first hydrogenation reactor is not as critical as the purity of the hydrogen-enriched gas used in the second hydrogenation reactor (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-enriched gas used for the second hydrogenation reactor 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 second hydrogenation effluent (130), the hydrogen-enriched gas used for the second hydrogenation reactor ideally contains little to no reactive nitrogen, such as ammonia. Specifically, the nitrogen content in the hydrogen-enriched gas (120) used for the second hydrogenation reactor should ideally not cause an increase in the nitrogen content of the liquid phase of the feed (110) for the second hydrogenation reactor when mixed with the first hydrogenation liquid (108) to form the feed (110) for the second hydrogenation reactor (102).

[0078] Therefore, the hydrogen enriched gas (120) used in the second hydrogenation reactor (102) may contain nitrogen impurities measured as nitrogen element, such as ≤10 wppm or less, such as ≤5 wppm, or such as ≤1 wppm.

[0079] 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.

[0080] As those skilled in the art will understand, when referring to nitrogen impurities, it is intended to include nitrogen impurities that can be 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 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. Nitrogen gas (N2) is not intended to be the equivalent of 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.

[0081] The second hydrogenation reactor (102) 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 hydrogenation inlet flow, 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.

[0082] The second hydrogenation reactor (102) 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.

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

[0084] The first hydrogenation liquid (106), together with a hydrogen enrichment gas (120), is introduced into a second hydrogenation reactor (102), where it is brought into contact with at least one catalyst zone at an inlet temperature and pressure that causes at least hydrogenated deoxygenation and hydrogenated denitrification to such an extent that the second hydrogenation liquid contains ≥99 wt% hydrocarbons and ≤1 wppm of nitrogen, preferably ≤0.4 wppm of nitrogen, for example ≤0.3 wppm of nitrogen (as detected by ASTM D4629) as measured as elemental nitrogen.

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

[0086] The first hydrogenation liquor does not need to be diluted with any diluent, such as hydrocarbons, before or during hydrogenation in the second hydrogenation reactor, nor is it intended to be diluted. Rather, the first hydrogenation liquor is used as feed to the second hydrogenation reactor. However, the first hydrogenation liquor can be mixed with other hydrocarbon feeds, provided that the first hydrogenation liquor is not mixed with a feed having a higher oxygen content than the first hydrogenation liquor, and that the first hydrogenation liquor is not mixed with a feed having a nitrogen content of ≥5 wppm.

[0087] Diluents are not necessary to control the exothermic properties of the hydrogenation reaction in the second hydrogenation reactor. Therefore, diluents such as hydrocarbon diluents do not need to be present in the second hydrogenation reactor; in other words, hydrocarbon diluents may not be introduced into the second hydrogenation reactor (102) in some cases.

[0088] There are many different inlet temperature and pressure combinations that will produce HDO and HDN to the extent that oxygen is removed from the remaining oxygenated hydrocarbons, thereby generating water as a byproduct, and nitrogen impurities are further removed from the first hydrogenation solution, thereby generating ammonia as a byproduct, and a second hydrogenation solution (112) containing lower amounts of nitrogen impurities than the first hydrogenation solution (108).

[0089] For example, the temperature and pressure at the inlet of the second hydrogenation reactor (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.

[0090] To induce more advanced HDO and HDN reactions, the temperature at the inlet of the first catalyst zone of the second hydrogenation reactor may be increased compared to the temperature at the inlet of the first catalyst zone of the first hydrogenation reactor. For example, the temperature at the inlet of the second hydrogenation reactor may be 10-15°C higher than the temperature at the inlet of the first hydrogenation reactor, or even higher.

[0091] Because the amount of oxygenated hydrocarbons in the first hydrogenation liquid is significantly less than that in the hydrogenation inlet flow of the first hydrogenation reactor, exothermic reactions are less likely to occur. This means that the temperature rise in the catalyst bed is not as high as that in the catalyst bed of the first hydrogenation reactor.

[0092] 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.

[0093] Therefore, the degree of hydrogenation deoxygenation and hydrogenation denitrification in the first hydrogenation reactor can be controlled in the second hydrogenation reactor in such a manner that the temperature rise between the reactor inlet and the reactor outlet 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).

[0094] To enhance the hydrogenation activity in the second hydrogenation reactor, 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 catalyst zone or multiple catalyst zones in the second hydrogenation reactor (102) have higher hydrogenation deoxygenation activity than the catalyst zone or multiple catalyst zones in the first hydrogenation reactor (101).

[0095] Catalyst activity can also be started to be the same in both the first and second hydrogenation reactors, for example, by using catalysts with the same activity in both reactors. Over time, the catalyst zone or multiple catalyst zones in the first hydrogenation reactor will deactivate faster than the catalyst zone or multiple catalyst zones in the second hydrogenation reactor, because a more impure feed, the hydrogenation inlet flow, is supplied to the first hydrogenation reactor, compared to a purer feed, the first hydrogenation fluid, supplied to the second hydrogenation reactor. Thus, the catalyst zone or multiple catalyst zones in the first hydrogenation reactor (101) will have lower hydrogenation deoxygenation activity than the catalyst zone or multiple catalyst zones in the second hydrogenation reactor (102). Catalyst activity can be measured in comparison to fresh catalyst.

[0096] 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 catalysts suitable for one or more catalyst zones of the first hydrogenation reactor, as well as further conditions.

[0097] The catalyst zone of the second 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 and / or present in the hydrogenation inlet stream and / or hydrogen-enriched gas.

[0098] The second hydrogenation reactor (102) lasts for 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.

[0099] More general reaction conditions for the second hydrogenation step may include a trickle bed reactor as the first hydrogenation reactor, comprising a catalyst zone containing a supported hydrogenation catalyst containing molybdenum, where the hydrogenation is carried out in the presence of hydrogen at a temperature of 250-400°C and a pressure between 10-150 bar, with a WHSV of 0.5-3 hours. -1 This range is and represents an H2 flow of 500-2100 Nl H2 / l feed.

[0100] The second hydrogenation effluent (130) from the second hydrogenation reactor (102) is subjected to one or more separation steps (111 and / or 114) in which the second hydrogenation effluent (130) is separated into a gaseous fraction (113) and the second hydrogenation liquid (112) and / or stripped hydrogenation liquid (115).

[0101] The separation step (111) 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 (130) into a gaseous fraction (113) and a second hydrogenation liquid (112). The separation step may be a high-temperature separation step overall, in which the effluent is not actively cooled. Not cooling the second hydrogenation effluent is beneficial in that less heating is required in subsequent steps, such as a first isomerization step. It may also be beneficial if the separated second hydrogenation liquid is used as a product recycling for diluting an oxygenated hydrocarbon feedstock.

[0102] The separation stage (114) is a stripper, using a gas, usually hydrogen, to remove impurities from the second hydrogenation effluent (130) or the second hydrogenation liquid (112). Hydrogen is usually used as the stripping gas because the stripping stage serves both purposes: to remove impurities and to ensure that a certain amount of hydrogen dissolves in the second hydrogenation liquid (112) and / or the stripped hydrogenation liquid (115) (which is beneficial if these liquids are transported to a hydrogen isomerization stage, such as the first isomerization reactor (103). The nitrogen content of the second hydrogenation liquid (112) and the stripped hydrogenation liquid (115), when stripping is used, is lower than the nitrogen content of the first hydrogenation liquid (108).

[0103] Therefore, the second hydrogenation effluent (130) from the second hydrogenation reactor (102) is stripped using a stripping gas (e.g., hydrogen) that is subjected to the stripping step (114), and the stripped hydrogenation liquid (115) is measured as having ≤0.4 wppm of nitrogen, for example ≤0.3 wppm of nitrogen (ASTM D4629 detection limit).

[0104] If necessary, for example, from the viewpoint of further purification, the second hydrogenation effluent (130) from the second hydrogenation reactor (102) is first subjected to a separation step (111), where the second hydrogenation effluent (130) is separated into a gaseous fraction (113) and a second hydrogenation liquid (112). Subsequently, the second hydrogenation liquid (112) is stripped in a stripping step (114) using a stripping gas (e.g., hydrogen), so that the stripped hydrogenation liquid (115) has, when measured as nitrogen, ≤0.4 wppm of nitrogen, for example, ≤0.3 wppm of nitrogen (detected by ASTM D4629).

[0105] 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 a first isomerization reactor (103).

[0106] However, as described above, it is also possible to use a separation step (111) comprising one or more high-pressure or low-pressure separators. This may be relevant when the second hydrogenation liquid is used as its own product or recycled into the process.

[0107] The second hydrogenation solution can be used either as a product of the process or recycled into the process.

[0108] The second hydrogenation liquid may also be isomerized in a first isomerization reactor (103) having at least one catalyst zone, where the second hydrogenation liquid and a hydrogen-enriched gas (H2) having ≤1 ppm (mol / mol) of nitrogen as measured as nitrogen element are introduced into the catalyst zone at an inlet temperature and pressure that causes at least hydrogen isomerization to produce a first isomerization effluent (116).

[0109] Furthermore, the hydrogen-enriched gas (120) is also necessary for hydrogenated deoxygenation (HDO) and hydrogenated denitrification (HDN) in the first and second hydrogenation reactors (101, 102), as described above, and the same applies to the first isomerization reactor (103).

[0110] The hydrogen-enriched gas may be excess hydrogen from the process (123, 131, 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.

[0111] The hydrogen-enriched gas used for the first isomerization reactor has a purity of 95% or higher. This is intended to minimize the risk of poisoning the catalyst zone of the first isomerization reactor. Therefore, the hydrogen-enriched gas used for the second hydrogenation reactor ideally contains little to no reactive nitrogen, such as ammonia.

[0112] Therefore, the hydrogen-enriched gas (120) used in the first isomerization reactor (103) may contain nitrogen impurities measured as elemental nitrogen, with a concentration of ≤1 ppm (mol / mol). 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.

[0113] 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.

[0114] The first isomerization reactor (103) is a vessel capable of accommodating 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.

[0115] The first 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 multiple fixed beds having the same or different catalyst particles, or a number of layers of catalyst particles of different activity and / or composition. The first isomerization reactor (103) may comprise a single catalyst zone.

[0116] The second hydrogenation effluent (112) or stripped hydrogenation effluent (115) is introduced together with a hydrogen enrichment gas (120) into the first 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 first isomerization effluent (116) to such an extent that the liquid portion (119) of the first isomerization effluent (116) contains ≥30 wt% branched hydrocarbons and / or an increase of ≥30 wt% branched hydrocarbons compared to the second hydrogenation effluent.

[0117] There are many different inlet temperature and pressure combinations that will cause hydrogenation denitrification to the extent that the first isomerized effluent (116) contains ≥30 wt% branched hydrocarbons and / or an increase of ≥30 wt% branched hydrocarbons compared to the second hydrogenation effluent.

[0118] For example, the temperature and pressure at the inlet of the first 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.

[0119] 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.

[0120] 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.

[0121] Those skilled in the art will know how to manipulate the above conditions to obtain a degree of hydrogen isomerization in which the liquid portion (119) of the first isomerized effluent (116) contains more branched hydrocarbons compared to the second hydrogenation solution. 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 solution.

[0122] 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, 1 to 4.5, or 1 to 2.5.

[0123] The degree of isomerization is often measured as the difference in cloud point between the feed and the product, in this case between the second hydrogenation solution and the liquid portion (119) of the first isomerization effluent, where the magnitude of the decrease in cloud point determines how extensive the hydrogen isomerization was. Thus, the first isomerization solution can be isomerized to such an extent that the decrease in cloud point from the second hydrogenation solution to the liquid portion (119) of the first isomerization effluent is 10°C or more.

[0124] 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.

[0125] For example, a second hydrogenation liquor (112) or second hydrogenation effluent (130) is subjected to a stripping step (114), where the second hydrogenation liquor or second hydrogenation effluent is stripped with a stripping gas (H2) such that the stripped hydrogenation liquor (115) has a lower nitrogen content compared to the second hydrogenation liquor (112), such as ≤0.4 wppm nitrogen, e.g., ≤0.3 wppm (ASTM D4629 detection); the hydrogenation liquor (115) and the stripped hydrogen-enriched gas (120), which has ≤1 ppm (mol / mol) nitrogen as measured by element, are introduced into a catalyst zone at a temperature and pressure that causes hydrogen isomerization to produce a first isomerized effluent (116). The hydrogenated liquid (115) stripped in a first isomerization reactor (103) having at least one catalyst zone is subjected to the step of isomerization; the first isomerized effluent (116) from the first isomerization reactor (103) is subjected to a separation step (117), where the first isomerized effluent (116) is separated into a gaseous fraction (118) and a first isomerized liquid (119), the first isomerized liquid containing ≥30 wt% branched hydrocarbons.

[0126] More general reaction conditions for the first isomerization step may include a trickle bed reactor as the first isomerization reactor, comprising a catalyst zone, the catalyst zone comprising a supported hydrogenation catalyst comprising W, Pt, or Pd, and a zeolite, wherein hydrogenation 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 isomerization effluent from the second hydrogenation treatment liquid 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.

[0127] The first isomerized effluent (116) from the first isomerization reactor (103) is subjected to a separation step (117), where the first isomerized effluent (116) is separated into a gaseous fraction (118) and the first isomerized liquid (119). The separation step (117) may be, for example, one or more high-pressure or low-pressure separators, which are known to those skilled in the art to be capable of separating the first isomerized effluent (116) into a gaseous fraction (118) and the 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.

[0128] 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.

[0129] The first isomerized effluent (116) or the first 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.

[0130] 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.

[0131] The first isomerized liquid (119) 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.

[0132] 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 a first hydrogenation reactor (101) having at least one catalyst zone (105). The first hydrogenation effluent (106) is separated in a separator (107) into a gaseous fraction (121) and a first 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) is mixed with a hydrogen-enriched gas (120) to form a feed (110) for a second hydrogenation reactor (102) having at least one catalyst zone, where hydrogenation deoxygenation and hydrogenation denitrification are induced to obtain a second hydrogenation effluent (130), which is separated in a separator (111) into a gaseous fraction (113) and a second hydrogenation liquid (112). The second hydrogenation liquid (112) is stripped together with hydrogen enrichment gas (120) in a stripper (114) to form a stripped hydrogenation liquid (115), which is mixed with the hydrogen enrichment gas (120) and supplied to a first isomerization reactor (103) having at least one catalyst zone, where the stripped hydrogenation liquid (115) is isomerized to obtain a first isomerized effluent (116), which is separated in a separator (117) into a gaseous fraction (118) and a first isomerized liquid (119).

[0133] 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).

[0134] 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).

[0135] 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.

[0136] 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]

[0137] 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.

[0138] [Table 1]

[0139] [Table 2]

[0140] [Table 3]

[0141] 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).

[0142] 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.

[0143] 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.

[0144] 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 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, for 1.1 hours. -1 The total feed rate WHSV is approximately 590 Nl H2 / l, with an H2 flow rate of approximately 590 Nl H2 / l, and the reaction temperature measured at the HDO reactor inlet is 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 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.

[0145] 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 reactor. The HDO reactor was connected to the polishing reactor as shown in Figure 1. The polishing reactor was a fixed-bed trickle-bed reactor 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 reactor, with a catalyst material quantity of 15,000 kg. The polishing reactor was operated under a pressure of 50 bar for approximately 2.7 hours. -1 The reactor is operated at a feed rate of WHSV, and the temperature at the policing reactor 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 8 vol-% of the amount of hydrogen used in the HDO reactor.

[0146] Table 4 shows the results of a test run using the setup shown in Figure 1, as described above, where the HDO reactor is accompanied downstream by a polishing reactor, where gaseous byproducts containing nitrogen compounds are removed between the two reactors. 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, as it affects the isomerization reaction, resulting in better cold flow characteristics under the same isomerization conditions compared to products with high nitrogen content before isomerization (data not shown).

[0147] The nitrogen content can be reduced to ≤0.4 w-ppm by changing process conditions, particularly by increasing the processing temperature of the polishing reactor. The final nitrogen impurity was ≤0.3 w-ppm in all runs (1-6). Increasing the temperature of the HDO reactor 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. -1 The 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)).

[0148] [Table 4]

[0149] 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 policing reactor (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.

[0150] 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.

[0151] 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.

[0152] 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-%.

[0153] [Table 5]

[0154] 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 reactor catalyst 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.

[0155] This reactor configuration was similar to the prior art reactor setup described in Patent Document 1.

[0156] 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.

[0157] 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 the HDO and policing reactor increased to 0.8 ppm or more. The increase in nitrogen content in isomerization resulted in reduced low-temperature properties and yields 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 a yield of 10 wt-% aviation fuel.

[0158] [Table 6]

[0159] Example 2: Degraded catalyst During the operation, the catalytic activity of the HDO catalyst bed tends to decrease, eventually reaching the end of its lifespan and requiring replacement of the catalyst material.

[0160] Run 20 below shows the results obtained when using an HDO catalyst bed after a significant operating time (i.e., reaching the end of the run), when the activity of the catalyst bed had decreased to two-thirds of the initial value of a fresh catalyst bed. Comparative Examples 1 and 2 (Runs 19 and 21) were also repeated using degraded catalysts with lower activity. The reaction conditions for Runs 19, 20, and 21 were as described in Comparative Example 1, Example 1, and Comparative Example 2, respectively, except that the HDO temperature was increased as described below.

[0161] The performance of the HDO reactor decreases as the catalyst activity declines towards the end of the operating cycle. This gradual catalyst deactivation can be compensated to some extent by increasing the temperature of the HDO catalyst bed. In this example, the HDO reactor temperature (T IN The temperature was raised from approximately 11°C, then approximately 309°C, to approximately 320°C at the end of the run in the catalyst.

[0162] As can be seen from the results in Table 7 below, the reactor setup according to the present invention still effectively removes nitrogen content even when using a catalyst that has reached the end point of the run.

[0163] [Table 7]

[0164] Example 3: Catalyst that has deteriorated beyond the end of the run. The reactor setups shown in Example 1 (Figure 1) and Comparative Examples 1 (Figure 2) and 2 (Figure 3) were used for a longer period compared to Example 2 (end-of-run experiment). The operating cycle was extended until the activity of the HDO reactor catalyst decreased to 60% of that of a fresh HDO catalyst.

[0165] This gradual degradation of the catalyst bed could no longer be compensated for by increasing the temperature of the HDO catalyst bed, as was done in the end-of-run experiment (Table 7), due to the risk of undesirable product formation. The temperature was maintained at the same value as measured at the end of the run in Example 2.

[0166] The results for nitrogen removal efficiency in the extended run cycle, shown in Table 8, demonstrate that the reactor setup (Figure 1) containing an HDO catalyst connected to a polishing bed reactor with removal of gaseous byproducts containing nitrogen-containing compounds was still able to maintain very low levels of nitrogen impurities, ≤0.3 ppm. In the comparative reactor setups (Figures 2 and 3), nitrogen residue levels began to rise, reaching 4.5 ppm and 4.2 ppm in the reactor setup with a single HDO catalyst bed and the reactor setup with two consecutive HDO catalyst beds, respectively.

[0167] Therefore, the results shown in Table 7 demonstrate that the reactor setup according to the present invention allows for operation to continue beyond catalyst deactivation, which would typically be characterized as the end of a run.

[0168] [Table 8]

[0169] The final nitrogen impurity content can be further reduced by increasing the processing temperature of the policing reactor. However, this does not apply to the HDO reactor. When the processing temperature of the HDO reactor is increased, this typically leads to uncontrollable reactions and reduced low-temperature properties. Table 4 shows the results of test runs (Experiments 1-6) using a setup including an HDO reactor with a point reactor downstream as shown in Figure 1, where both reactors have fresh catalyst beds and gaseous byproducts containing nitrogen compounds are removed between the two reactors.

[0170] Notably, despite the increase in nitrogen content in the liquid paraffin effluent stream after HDO was introduced into the policing reactor, the final nitrogen content in the inflow stream to the isomerization reactor remained very low.

Claims

1. A process for preparing hydrocarbons from an oxygenated hydrocarbon feedstock having nitrogen impurities of 300 wppm or more as measured as elemental nitrogen, A first hydrogenation reactor (101) comprising at least one catalyst zone (105), wherein a hydrogenation inlet flow comprising an oxygenated hydrocarbon feedstock (104) and a hydrocarbon diluent (126) is introduced into the catalyst zone together with a hydrogen-enriched gas (120) at an inlet temperature and pressure that causes at least hydrogen deoxygenation and hydrogen denitrification to such an extent that the first hydrogenation effluent (106) from the first hydrogenation reactor (101) consists mainly of hydrocarbons, and the oxygenated hydrocarbon feedstock is converted to ≥95% hydrocarbons; The first hydrogenation effluent (106) from the first hydrogenation reactor is separated into a gaseous fraction (121) and a first hydrogenation liquid (108), at least a portion of which is subjected to a separation step (107) in which the first hydrogenation liquid contains ≥95 wt% hydrocarbons and >1 wppm nitrogen; At least a portion of the first hydrogenation liquid (108) and the hydrogen enrichment gas (120) are introduced into a second hydrogenation reactor (102) including at least one catalyst zone at an inlet temperature that causes hydrogenation deoxygenation and hydrogenation denitrification, and at a temperature and pressure higher than the inlet temperature in the first hydrogenation reactor, wherein the first hydrogenation liquid is not mixed with a feed having an oxygen content higher than the oxygen content of the first hydrogenation liquid, and the first hydrogenation liquid is not mixed with a feed having a nitrogen content higher than the nitrogen content of the first hydrogenation liquid; The second hydrogenation effluent (130) from the second hydrogenation reactor (102) is subjected to one or more separation steps (111 and / or 114), where the second hydrogenation effluent (130) is separated into a gaseous fraction (113) and a second hydrogenation liquid (112) and / or stripped hydrogenation liquid (115), the second hydrogenation liquid (112) and / or stripped hydrogenation liquid (115) containing ≥99 wt% hydrocarbons and ≤1 wppm of nitrogen as measured as elemental nitrogen; Optionally, the second hydrogenated liquid (112) or the stripped hydrogenated liquid (115) is isomerized in a first isomerization reactor (103) including at least one catalyst zone, wherein the second hydrogenated liquid and a hydrogen-enriched gas (120) having ≤1 ppm (mol / mol) nitrogen as measured as nitrogen element are introduced into the catalyst zone at an inlet temperature and pressure that causes at least hydrogen isomerization to produce a first isomerized effluent (116); The first isomerized effluent (116) from the first isomerization reactor (103) is subjected to a separation step (117), where the first isomerized effluent (116) is separated into a gaseous fraction (118) and a first 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 second hydrogenated liquid; and The temperature and pressure at the inlet of the first hydrogenation reactor (101) are 200 to 400°C and 10 to 150 bar, and The temperature and pressure at the inlet of the second hydrogenation reactor (102) are 250 to 450°C and 10 to 150 bar, The degree of hydrogenation deoxygenation and hydrogenation denitrification in the first hydrogenation reactor is controlled in such a manner that the temperature rise between the reactor inlet and the reactor outlet in the second hydrogenation reactor does not exceed 10°C. process.

2. The separation step includes subjecting the second hydrogenation liquid (112) or second hydrogenation effluent (130) to a stripping step (114), wherein the second hydrogenation liquid or second hydrogenation effluent is stripped using a stripping gas (120) such that the stripped hydrogenation liquid (115) has a nitrogen content of ≤0.4 wppm as measured by element; A step of isomerizing the stripped hydrogenation liquid (115) in a first isomerization reactor (103) including at least one catalyst zone, wherein the stripped hydrogenation liquid (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 hydrogen denitrification to produce a first isomerization effluent (116); The first isomerized effluent (116) from the first isomerization reactor (103) is subjected to a separation step (117), where the first isomerized effluent (116) is separated into a gaseous fraction (118) and a first isomerized liquid (119), the first isomerized liquid containing ≥30 wt% branched hydrocarbons. The process according to claim 1.

3. The process according to claim 1 or 2, wherein the first isomerized liquid (119) is separated into at least aviation fuel having a cloud 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 first hydrogenation liquid (106) to such an extent that the first hydrogenation liquid (108) has a temperature lower than the temperature of the inlet to the first catalyst zone of the first hydrogenation reactor.

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

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

7. The process according to any one of claims 1 to 6, wherein the hydrogen enriched gas (120) used in the second hydrogenation reactor (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 first hydrogenation reactor (101) are 200 to 400°C and 10 to 150 bar.

9. The process according to any one of claims 1 to 8, wherein the first hydrogenation reactor (101) includes at least three catalyst zones.

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

11. The first 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 10, operated in a flow.

12. The process according to any one of claims 1 to 11, wherein the temperature and pressure at the inlet of the second hydrogenation reactor (102) are 250 to 450°C and 10 to 150 bar.

13. The process according to any one of claims 1 to 12, wherein the second hydrogenation reactor (102) comprises a single catalyst zone.

14. The process according to any one of claims 1 to 13, wherein the catalyst zone of the second hydrogenation reactor comprises one or more catalysts selected from metal hydrides supported on a carrier.

15. The second hydrogenation reactor (102) is used 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 14, operated in a flow.

16. The process according to any one of claims 1 to 15, wherein the temperature and pressure at the inlet of the first isomerization reactor (103) are 280 to 370°C and 20 to 50 bar.

17. The process according to any one of claims 1 to 16, wherein the catalyst zone of the first 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.

18. The process according to claim 17, wherein the one or more catalysts further comprises molecular sieves.

19. The isomerization reactor (103) has a WHSV in the range of 0.5 to 1 h -1 and is operated at a H flow of 300 to 500 Nl H 2 / l feed in accordance with any one of claims 1 to 18. 2 The process according to any one of claims 1 to 18, wherein the process is operated at a H flow of 300 to 500 Nl H

20. The process according to any one of claims 1 to 19, wherein the first isomerizing solution has an isoparaffin-to-n-paraffin ratio greater than 1.

21. The process according to any one of claims 1 to 20, wherein the hydrogenation treatment inlet flow contains 100 to 500 wppm of nitrogen impurities.

22. The process according to any one of claims 1 to 21, wherein the first hydrogenation effluent (106) from the first hydrogenation reactor contains 100 to 500 wppm or more of nitrogen impurities.

23. The process according to any one of claims 1 to 22, wherein the second hydrogenated liquid (112) and / or the stripped hydrogenated liquid (115) contains ≥99 wt% hydrocarbons and ≤0.3 wppm nitrogen as measured as elemental nitrogen.

24. The process according to any one of claims 1 to 23, wherein the hydrocarbon diluent (126) is a product recycled.

25. The process according to any one of claims 1 to 24, wherein the oxygenated hydrocarbon feedstock may contain 25 wt% or more of a fatty acid or fatty acid ester.

26. The process according to any one of claims 1 to 25, wherein the oxygenated hydrocarbon feedstock may be selected from plant oils and animal fats.

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