Method for processing a phosphorus-containing hydrocarbon stream

Abstract

The invention relates to a process for processing a phosphorus (P)-containing hydrocarbon stream (1), the process comprising the following steps: - providing the hydrocarbon stream (1); - separating a P-rich fraction (9) from the hydrocarbon stream (1), wherein the P-rich fraction (9) has a boiling range with a lower end of at least 350 °C and a P content of at least 10 ppm; - processing the P-rich fraction (9) in a fluid catalytic cracking (FCC) unit (20).

Description

[0001] The present invention relates to methods for processing a phosphorus (P)-containing hydrocarbon stream.

[0002] Refinery processes utilize material streams of diverse origins, which may contain various impurities. Silicon (Si) and phosphorus (P) play a significant role in this context. For example, material streams can be contaminated by silicone oils, which are used as lubricants and sealants in refinery equipment. Silicone oils are also sometimes used as process additives or antifoaming agents, for example in coke cores or thermal gas oil units (TGUs). Phosphorus compounds are also frequently used as additives, such as corrosion inhibitors, which can result in phosphorus-containing impurities.

[0003] Such impurities are particularly significant in connection with synthetic crude oils. Synthetic crude oil, sometimes also referred to as syncrude, can be obtained through various processes. For example, synthetic crude oil can be shale oil, which is extracted from oil shale by pyrolysis. Another source is hydrocarbons, especially bitumen, extracted from oil sands, from which synthetic crude oil can be obtained through upgrading. Furthermore, synthetic crude oil can also be produced from plastic materials, such as plastic waste, through cracking.Another source of synthetic crude oils is biomass, wood, and other biological raw materials, which may already contain naturally occurring organic phosphorus compounds (such as phospholipids and nucleic acids) and to which silicon and phosphorus compounds are often added in the form of impregnations and surface treatments (such as flame retardants, surface enhancements with silicones, silicone adhesives, etc.). Synthetic crude oils typically contain various impurities that can adversely affect refining processes and refinery equipment, or even render the crude oil completely unsuitable for certain refining processes. The type and concentration of impurities can vary considerably depending on the source and method used to obtain the synthetic crude oil. However, silicon and phosphorus play a significant role.

[0004] Silicon (Si) and phosphorus (P) can cause problems in various refinery processes. For example, Si and P compounds can be detrimental to catalysts in hydrogenation plants, leading to vitrification. Typically, Si and P must therefore be removed before such a process. Separation is usually achieved using complex guard beds. However, guard beds incur ongoing costs and require regular replacement, which in turn necessitates plant shutdowns. When handling large volumes of hydrocarbon streams, guard beds become quickly overloaded even with low Si or P concentrations and require frequent replacement.

[0005] There is therefore a need for new and improved methods to utilize hydrocarbon streams containing silicon and / or phosphorus. It is an object of the present invention to provide such methods.

[0006] The present invention therefore relates to a process for processing a phosphorus (P)-containing hydrocarbon stream, the process comprising the following steps: Provision of the hydrocarbon stream; separation of a phosphorus-rich fraction from the hydrocarbon stream, wherein the phosphorus-rich fraction has a boiling range with a lower end of at least 350 °C and a phosphorus content of at least 10 ppm; processing of the phosphorus-rich fraction in a Fluid Catalytic Cracking (FCC) unit.

[0007] In a preferred embodiment, the hydrocarbon stream is a phosphorus (P) and silicon (Si)-containing hydrocarbon stream, wherein, in addition to the P-rich fraction, a Si-rich fraction is separated from the hydrocarbon stream, wherein the Si-rich fraction has a boiling range with a lower end of at least 120 °C and a Si content of at least 10 ppm, and wherein the P-rich fraction and the Si-rich fraction are processed in the FCC unit.

[0008] Up to now, the prior art has generally assumed that impurities must be removed from hydrocarbon streams prior to refinery processes such as FCC. For example, WO 2021 / 201932 A1 describes a process for the pyrolysis of plastic waste, whereby the entire liquid fraction from the pyrolysis is fed to an FCC unit. It is expressly stated that impurities—including numerous others such as phosphorus compounds and silica—must be removed from the plastic waste to levels preferably below 5 ppm (WO 2021 / 201932 A1,

[0036] ). If this is not achieved, a separate guard bed must be provided for the removal of the impurities (WO 2021 / 201932 A1,

[0037] ). In addition, a pretreater unit can be provided upstream of the FCC unit to remove sulfur, nitrogen, phosphorus, silica, dienes and metals (WO 2021 / 201932 A1,

[0014] ).

[0009] In the course of the present invention, it has surprisingly been found that, in the case of Si and P compounds, it is not necessary to remove them prior to an FCC process. Moreover, surprisingly, an FCC unit can even be used specifically for the removal of such compounds. This is impressively demonstrated by the examples contained herein, in which hydrocarbon streams overloaded with silicone oil or organic P compounds could still be treated without problems in an FCC unit even at concentrations of 1 wt% (i.e., 10,000 ppm). Si and P were efficiently removed even at these high concentrations.

[0010] Without being bound to any specific theory, the inventors explain this by stating that during the FCC process, any organic components of Si and P compounds are cleaved, formally forming SiO₂ or PO₄³⁻ groups. Unlike hydrogenation plants, where the top layer of the catalyst can vitrify, the SiO₂ or PO₄³⁻ groups do not harm the FCC process. Instead, they can even extend the basic structure of FCC catalysts. Zeolites, which consist of a silicate framework and may be modified with phosphate groups in the active site, are regularly used as catalysts in FCC processes. According to the inventors, the SiO₂ or PO₄³⁻ groups formed in the process can attach to existing catalysts and subsequently act as catalysts themselves, or at least not negatively affect the catalyst activity.This effect is particularly advantageous when a zeolite is already used as the starting catalyst; however, the use of other catalysts is also possible.

[0011] In connection with the invention, "P-containing" is preferably understood to mean a P content of at least 0.1 ppm, preferably at least 1 ppm, and in particular at least 10 ppm.

[0012] Preferably, the hydrocarbon stream contains organic phosphorus compounds, more preferably triarylphosphites and / or triaryl phosphates. Triarylphosphites are used, for example, as additives in plastics, e.g., as flame retardants. During the pyrolysis of plastic material, triarylphosphites can be partially converted into stable triaryl phosphates. Therefore, synthetic crude oils obtained from the depolymerization of plastics, for example, can contain significant amounts of triarylphosphites and / or triaryl phosphates. It is therefore also preferred if the hydrocarbon stream is generated from the depolymerization of plastic material containing triarylphosphites. Preferably, the triarylphosphites are tris(2,4-di-tert-butylphenyl)phosphite, trisphenylphosphite, and / or tristolylphosphite. It is particularly preferred if the triarylphosphite is Tris(2,4-di-tert-butylphenyl)phosphite (CAS Registry number 31570-04-4).Preferably, the concentration of organic phosphorus compounds, in particular the aforementioned preferred organic phosphorus compounds, in the hydrocarbon stream is at least 0.1 ppm, preferably at least 1 ppm, in particular at least 10 ppm.

[0013] Preferably, the phosphorus-rich fraction has a phosphorus content of at least 20 ppm, preferably at least 30 ppm, more preferably at least 40 ppm, more preferably at least 50 ppm, more preferably at least 60 ppm, more preferably at least 70 ppm, more preferably at least 80 ppm, more preferably at least 90 ppm, more preferably at least 100 ppm. It is particularly preferred if the phosphorus content is between 10 and 10000 ppm, more preferably between 15 and 2000 ppm, more preferably between 20 and 800 ppm, more preferably between 30 and 700 ppm, more preferably between 40 and 600 ppm, more preferably between 50 and 550 ppm, more preferably between 60 and 500 ppm, more preferably between 70 and 450 ppm, more preferably between 80 and 400 ppm, more preferably between 90 and 350 ppm, more preferably between 100 and 300 ppm.

[0014] Preferably, a low-P FCC product is obtained by processing the P-rich fraction in the FCC unit.

[0015] In this context, "low phosphorus" preferably means a lower phosphorus content than "high phosphorus," i.e., the low phosphorus FCC product has a lower phosphorus content than the high phosphorus fraction. Preferably, the low phosphorus FCC product has a phosphorus content of less than 10 ppm, more preferably less than 5 ppm, more preferably less than 1 ppm, and more preferably less than 0.5 ppm.

[0016] Within the scope of the invention, it has been shown that phosphorus compounds are typically present, particularly in hydrocarbon fractions with boiling ranges above 350 °C. This applies especially to the triarylphosphites and triarylphosphates mentioned above. If the phosphorus-rich fraction has a boiling range with a lower end of at least 350 °C, a large proportion of the phosphorus compounds can therefore be separated from the hydrocarbon stream without carrying along valuable, lighter fractions with boiling ranges below 350 °C. These lighter fractions can thus advantageously be used elsewhere. It is therefore preferred if the phosphorus-rich fraction has a boiling range with a lower end of at least 350 °C, preferably at least 360 °C, more preferably at least 370 °C, more preferably at least 380 °C, more preferably at least 385 °C, more preferably at least 390 °C, more preferably at least 395 °C, more preferably at least 400 °C.

[0017] To ensure that the most important phosphorus compounds are separated with the phosphorus-rich fraction, it is also advantageous if the lower end of the boiling range of the phosphorus-rich fraction is not too high. Therefore, the lower end of the boiling range is preferably between 350 °C and 500 °C, more preferably between 360 °C and 480 °C, more preferably between 370 °C and 470 °C, more preferably between 380 °C and 460 °C, more preferably between 385 °C and 450 °C, more preferably between 390 °C and 440 °C, more preferably between 395 °C and 430 °C, and more preferably between 400 °C and 420 °C.

[0018] In embodiments of the process according to the invention, it is further preferred if the phosphorus-rich fraction has a boiling range with an upper limit of at most 1000 °C, preferably at most 900 °C, more preferably at most 800 °C, more preferably at most 700 °C, more preferably at most 600 °C, and more preferably at most 500 °C. Preferably, the upper limit of the boiling range lies between 450 °C and 1000 °C, more preferably between 500 °C and 900 °C, and more preferably between 600 °C and 800 °C. By providing a boiling range with a lower and an upper limit as indicated, those fractions containing the most important phosphorus compounds can be selectively separated from the hydrocarbon stream.

[0019] Within the scope of the invention, it has proven advantageous to subject the phosphorus-rich fraction to solids removal before processing in the FCC unit. Preferably, the solids-depleted phosphorus-rich fraction is processed in the FCC unit. It has been found that the phosphorus-rich fraction can frequently contain solids, for example, inorganic salts. Such solids can have a negative impact on the FCC unit and damage the FCC catalyst. This is particularly true if the hydrocarbon stream is a synthetic crude oil stream, for example, a synthetic crude oil stream obtained from the depolymerization of plastic material. Plastic material can often contain fillers and similar additives, which can result in higher solids contents in the synthetic crude oil stream and, consequently, in the phosphorus-rich fraction.

[0020] Solids reduction is preferably understood here to mean a reduction in the solids content. Preferably, the solids content of the phosphorus-rich fraction processed in the FCC unit is less than 3 wt.%, more preferably less than 1 wt.%, even more preferably less than 0.5 wt.%, even more preferably less than 0.3 wt.%, even more preferably less than 0.2 wt.%, and even more preferably less than 0.1 wt.%. The solids content is preferably determined according to standard ASTM D5631-21.

[0021] Solid removal can occur before or after separating the phosphorus-rich fraction from the hydrocarbon stream; that is, the phosphorus-rich fraction can also pass through solid removal as part of the hydrocarbon stream. Furthermore, additional steps can take place between solid removal and processing the phosphorus-rich fraction in the FCC unit; for example, further fractions can be separated from the solid-depleted phosphorus-rich fraction.

[0022] To minimize negative effects on the FCC process and the FCC catalyst, it is preferred that the phosphorus-rich fraction processed in the FCC unit has an ash content of less than 0.1 wt%, preferably less than 0.05 wt%, more preferably less than 0.02 wt%, and more preferably less than 0.01 wt%. The ash content can preferably be determined according to ISO 6245:2002.

[0023] To minimize negative effects on the FCC process and the FCC catalyst, it is also preferred that the phosphorus-rich fraction processed in the FCC unit exhibits low coke formation. Preferably, the phosphorus-rich fraction has a Conradson carbon residue (CCR) of less than 0.5 wt%, more preferably less than 0.2 wt%, more preferably less than 0.1 wt%, and more preferably less than 0.05 wt%. The CCR can preferably be determined according to ASTM D189-06(2019).

[0024] In a preferred embodiment, the solids removal process comprises the following steps: adding a solvent to the phosphorus-rich fraction to form a mixture; separating solids from the mixture. Adding a solvent to the phosphorus-rich fraction has the advantage that waxes present in the phosphorus-rich fraction can be at least partially dissolved in the solvent and thus separated particularly well from the unwanted solids.

[0025] The solvent can be added to the phosphorus-rich fraction using an introduction device. The introduction device may include a metering unit, such as a metering pump. For the addition of the solvent, the phosphorus-rich fraction can be fed into a container to which the introduction device may be connected. The container may be heated so that the dissolution of wax contained in the phosphorus-rich fraction in the solvent can occur at a specific temperature.

[0026] Preferably, the mixture has a temperature of at least 80 °C, more preferably at least 100 °C, even more preferably at least 120 °C, even more preferably 140 °C, and even more preferably at least 160 °C. At such a high temperature, waxes present in the phosphorus-rich fraction can be dissolved even more effectively, and solids can be removed even more efficiently. In particular, it is preferred that the mixture has a temperature in the range of 80 to 240 °C, more preferably 100 to 160 °C, and even more preferably 100 to 140 °C.

[0027] The mixture can preferably be subjected to a pressure in the range of 1 to 25 bar, particularly in the range of 5 to 16 bar. This allows for further improvement of the process control and rapid dissolution of wax in the solvent.

[0028] The solvent preferably has a boiling point (or boiling range) in the range of 20 to 270 °C, more preferably 20 to 250 °C, more preferably 35 to 200 °C, and even more preferably 50 to 150 °C. This has proven particularly advantageous for the efficient dissolution of wax and also enables efficient subsequent separation of the solvent. The boiling point (or boiling range) of the solvent can be determined according to ASTM D5399-09:2017 or ASTM D2887-22:2022.

[0029] In a preferred embodiment, the solvent comprises at least 10 wt.%, more preferably at least 20 wt.%, even more preferably at least 50 wt.%, even more preferably at least 70 wt.%, and even more preferably at least 90 wt.%, of an aliphatic hydrocarbon, based on the total weight of the solvent. Preferably, the solvent consists of a single aliphatic hydrocarbon or a mixture of two or more aliphatic hydrocarbons. With an increasing proportion of aliphatic hydrocarbon, not only can the solvent's ability to dissolve wax improve, but the solubility of solids in the solvent can also be reduced. Conversely, with a high proportion of aromatics in the solvent, certain solids, such as asphaltenes or tar, may partially dissolve in the solvent, which can make separation more difficult.

[0030] The aliphatic hydrocarbon is preferably selected from the group of aliphatic hydrocarbons with up to 15 carbon atoms per molecule, particularly those with 4 to 12 carbon atoms per molecule. n-Pentane, n-Hexane, n-Heptane, iso-Dodecane, n-Tetradecane, or a mixture thereof have proven to be particularly suitable.

[0031] The mass ratio between the phosphorus-rich fraction and the solvent can preferably be in the range of 3:1 to 1:5, more preferably in the range of 1:1 to 1:3. This allows the dissolution of waxes in the solvent to occur quickly and as completely as possible.

[0032] The separation of solids from the mixture can be carried out by any separation method, preferably by gravimetric separation, filtration, and / or centrifugal separation. The gravimetric separation can include sedimentation and / or decantation. In particular, separation can be achieved by filtration. Filtration can be performed using a filter medium, which may include activated carbon or bleaching earth. This allows any polar components dissolved in the solvent along with the wax (e.g., tar or polyphenol) to be effectively separated and adsorbed by the filter medium. Even small particles can be effectively removed by filtration.

[0033] The solids may preferably comprise inorganic salts, ceramic raw materials, asphaltenes, tar, and / or coke. In particular, the solids may comprise talc, iron oxide (e.g., iron(III) oxide), aluminum oxide, titanium dioxide, magnesium oxide, and / or calcium carbonate. If the hydrocarbon stream is a synthetic crude oil stream, especially from the depolymerization of plastic material, the solid may comprise an additive contained in the plastic material. For example, the additive may comprise a filler, a color pigment, and / or an additive.

[0034] In a preferred embodiment, after separating the solids from the mixture, at least a portion of the solvent is separated from the mixture. This solvent separation preferably takes place before processing in the FCC unit. This separation makes it possible to reduce the amount of material processed in the FCC unit and thus increase the efficiency of the process.

[0035] The separation of the solvent can involve evaporation or extraction under pressure. Preferably, the solvent separation is carried out at a temperature in the range of 50 to 280 °C, more preferably from 80 to 150 °C, and even more preferably from 100 to 130 °C. Preferably, the solvent separation is carried out at a pressure in the range of 0.1 to 2.5 bar, more preferably from 0.5 to 1 bar.

[0036] In a preferred embodiment, at least a portion of the separated solvent is reused for solids removal. Prior to being recycled back into the process, the solvent can preferably be further purified, preferably by evaporation, in particular by rotary evaporation.

[0037] In a preferred embodiment, the hydrocarbon stream is a phosphorus (P) and silicon (Si)-containing hydrocarbon stream, wherein, in addition to the P-rich fraction, a Si-rich fraction is separated from the hydrocarbon stream, the Si-rich fraction having a boiling range with a lower end of at least 120 °C and a Si content of at least 10 ppm, and wherein the P-rich fraction and the Si-rich fraction are processed in the FCC unit. Preferably, a P- and Si-poor FCC product is obtained from processing the P-rich fraction and the Si-rich fraction.

[0038] A process for processing a silicon (Si)-containing hydrocarbon stream is also disclosed, comprising the following steps: providing the hydrocarbon stream; separating a Si-rich fraction from the hydrocarbon stream, wherein the Si-rich fraction has a boiling range with a lower end of at least 120 °C and a Si content of at least 10 ppm; and processing the Si-rich fraction in a fluid catalytic cracking (FCC) unit. This process can also be used independently of the process described above for processing a phosphorus-containing hydrocarbon stream.

[0039] A preferred embodiment relates to a process for processing a hydrocarbon stream containing phosphorus (P) and silicon (Si), the process comprising the following steps: Providing the hydrocarbon stream; separating a phosphorus-rich fraction from the hydrocarbon stream, wherein the phosphorus-rich fraction has a boiling range with a lower end of at least 350 °C and a phosphorus content of at least 10 ppm; Separation of a Si-rich fraction from the hydrocarbon stream, wherein the Si-rich fraction has a boiling range with a lower end of at least 120 °C and a Si content of at least 10 ppm; processing of the P-rich fraction and the Si-rich fraction in a Fluid Catalytic Cracking (FCC) unit.

[0040] Preferably, a low-P and low-Si FCC product is obtained from processing the P-rich fraction and the Si-rich fraction.

[0041] In connection with the invention, "Si-containing" is preferably understood to mean a Si content of at least 0.1 ppm, preferably at least 1 ppm, and in particular at least 10 ppm. Preferably, the hydrocarbon stream contains organic Si compounds, preferably silicone oils or siloxanes, more preferably dimethylsiloxanes, in particular cyclic dimethylsiloxanes, preferably selected from the group consisting of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane. Preferably, the concentration of organic Si compounds, in particular of the aforementioned preferred organic Si compounds, in the hydrocarbon stream is at least 0.1 ppm, preferably at least 1 ppm, and in particular at least 10 ppm.

[0042] Preferably, the Si-rich fraction has a Si content of at least 20 ppm, preferably at least 30 ppm, more preferably at least 40 ppm, more preferably at least 50 ppm, more preferably at least 60 ppm, more preferably at least 70 ppm, more preferably at least 80 ppm, more preferably at least 90 ppm, more preferably at least 100 ppm. It is particularly preferred if the Si content is between 10 and 10000 ppm, more preferably between 15 and 2000 ppm, more preferably between 20 and 800 ppm, more preferably between 30 and 700 ppm, more preferably between 40 and 600 ppm, more preferably between 50 and 550 ppm, more preferably between 60 and 500 ppm, more preferably between 70 and 450 ppm, more preferably between 80 and 400 ppm, more preferably between 90 and 350 ppm, more preferably between 100 and 300 ppm.

[0043] Preferably, a low-Si FCC product is obtained by processing the Si-rich fraction in the FCC unit.

[0044] In this context, "low-Si" preferably means a lower silicon content than "high-Si", i.e., the low-Si FCC product has a lower silicon content than the high-Si fraction. Preferably, the low-Si FCC product has a silicon content of less than 10 ppm, more preferably less than 5 ppm, more preferably less than 1 ppm, and more preferably less than 0.5 ppm.

[0045] Within the scope of the invention, it has been shown that silicon compounds can typically be present, particularly in hydrocarbon fractions with boiling ranges above 120 °C. If the hydrocarbon stream is, for example, a synthetic crude oil stream produced from a starting material containing silicon polymers—such as a hydrocarbon stream obtained from the depolymerization of plastic material—the hydrocarbon stream can contain large quantities of cyclic dimethylsiloxanes, which are formed from the silicon polymers during pyrolysis. These can be, in particular, the following compounds: Hexamethylcyclotrisiloxane (boiling point: 134-135 °C); Octamethylcyclotetrasiloxane (boiling point: 171-175 °C); Decamethylcyclopentasiloxane (boiling point: 210 °C); Dodecamethylcyclohexasiloxane (boiling point: 245 °C).

[0046] Silicone oils, which are used as antifoaming agents or as lubricants and sealants, often also have boiling points > 200 °C.

[0047] If the silicon-rich fraction has a boiling range with a lower end of at least 120 °C, a large proportion of the silicon compounds can be separated from the hydrocarbon stream without carrying over valuable lighter fractions with boiling ranges below 120 °C. These lighter fractions can therefore advantageously be used elsewhere. It is preferred if the silicon-rich fraction has a boiling range with a lower end of at least 125 °C, preferably at least 130 °C, more preferably at least 135 °C, more preferably at least 140 °C, more preferably at least 145 °C, more preferably at least 150 °C, more preferably at least 155 °C, more preferably at least 160 °C, more preferably at least 170 °C. This allows the silicon compounds to be separated even more selectively and even larger boiling ranges to be used elsewhere.

[0048] To ensure that the most important silicon compounds are separated with the silicon-rich fraction, it is also advantageous if the lower end of the boiling range of the silicon-rich fraction is not too high. Therefore, the lower end of the boiling range is preferably between 120 °C and 230 °C, more preferably between 130 °C and 220 °C, more preferably between 140 °C and 210 °C, more preferably between 145 °C and 205 °C, more preferably between 150 °C and 200 °C, more preferably between 155 °C and 195 °C, more preferably between 160 °C and 190 °C, more preferably between 165 °C and 185 °C, and more preferably between 170 °C and 180 °C.

[0049] In embodiments of the process according to the invention, it is also preferred if the Si-rich fraction has a boiling range with an upper end of at most 500 °C, preferably at most 450 °C, more preferably at most 400 °C, more preferably at most 350 °C, more preferably at most 300 °C, more preferably at most 280 °C, more preferably at most 270 °C, more preferably at most 260 °C, more preferably at most 255 °C, more preferably at most 250 °C, more preferably at most 245 °C, more preferably at most 240 °C, more preferably at most 235 °C, more preferably at most 230 °C, more preferably at most 225 °C. Preferably, the upper end of the boiling range lies between 205 °C and 500 °C, more preferably between 210 °C and 400 °C, more preferably between 215 °C and 300 °C, more preferably between 220 °C and 280 °C, more preferably between 225 °C and 260 °C, more preferably between 230 °C and 250 °C, more preferably between 235 °C and 245 °C.By defining a boiling range with a lower and an upper limit as specified, those fractions containing the most important silicon compounds can be selectively extracted from the hydrocarbon stream. This applies particularly to the cyclic dimethylsiloxanes mentioned above. Defining the specified boiling ranges is therefore especially advantageous when the hydrocarbon stream is a synthetic crude oil stream, particularly one obtained from the depolymerization of plastic materials.

[0050] In a preferred embodiment of the process according to the invention, a light fraction is separated from the hydrocarbon stream in addition to the silicon-rich fraction. Preferably, the light fraction is a naphtha fraction. Preferably, the light fraction has a boiling range with an upper limit of at most 200 °C, more preferably at most 190 °C, more preferably at most 180 °C, more preferably at most 170 °C, and more preferably at most 160 °C. Choosing such a boiling range for the light fraction has the advantage that significant silicon compounds are generally not contained in it, and the light fraction can thus be further used without additional removal of silicon compounds, for example as a valuable naphtha fraction, e.g., in a naphtha hydrotreating plant.

[0051] In a preferred embodiment, the light fraction has a silicon content of less than 20 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, and more preferably less than 1 ppm. Likewise, it is preferred that the light fraction has a phosphorus content of less than 20 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, and more preferably less than 1 ppm.

[0052] Within the scope of the invention, it has proven advantageous to wash the silicon-rich fraction with at least one aqueous washing solution before processing it in the FCC unit. Preferably, the washed silicon-rich fraction is processed in the FCC unit. Such washing removes undesirable compounds that may be present in the silicon-rich fraction and that could have negative effects on the FCC unit. For example, hydrocarbon streams often contain basic compounds, such as amines, which can partially deactivate the typically acidic FCC catalyst. This is particularly the case when the hydrocarbon stream is a synthetic crude oil stream. For example, amines from polyamide contained in plastic material or from biomass can enter the silicon-rich fraction. An aqueous wash removes such basic compounds, especially amines, before they enter the FCC unit.Washing with the at least aqueous washing solution can take place before or after separating the silicon-rich fraction from the hydrocarbon stream; that is, the silicon-rich fraction can also pass through the washing process as part of the hydrocarbon stream. Further steps can also be performed between washing the silicon-rich fraction and processing in the FCC unit; for example, additional fractions can be separated from the washed silicon-rich fraction.

[0053] In this context, it is particularly preferred if the pH value of the at least one aqueous washing solution is less than 8, preferably less than 7, more preferably less than 6, more preferably less than 5, more preferably less than 4, more preferably less than 3, more preferably less than 2, and most preferably less than 1. This enables particularly efficient removal of basic compounds. It is particularly preferred if the pH value of the aqueous washing solution is in the range of 0 to 8, more preferably 0.5 to 7, more preferably 1 to 6, more preferably 1 to 5, more preferably 2 to 4, and most preferably 2.5 to 3.5.

[0054] In a preferred embodiment, the at least one aqueous washing solution contains sulfuric acid. Preferably, the concentration of sulfuric acid is between 0.5 and 10 wt.%, in particular between 1 and 5 wt.%.

[0055] Preferably, washing with the at least one aqueous washing solution is carried out at a temperature of at least 20 °C, preferably at least 30 °C, more preferably at least 40 °C, more preferably at least 50 °C, more preferably at least 60 °C, and more preferably at least 70 °C. Using such a high temperature allows for particularly thorough removal of the unwanted basic compounds. It is especially preferred if the washing is carried out at a temperature in the range of 20 °C to 120 °C, preferably from 30 °C to 110 °C, more preferably from 40 °C to 100 °C, even more preferably from 50 °C to 90 °C, and even more preferably from 60 °C to 80 °C.

[0056] Typically, washing the silicon-rich fraction with an aqueous washing solution involves mixing the silicon-rich fraction with the aqueous washing solution, followed by separation of the washed silicon-rich fraction. Preferably, the washing is carried out in a mechanical mixer, a static mixer, and / or a mixer-settler. Washing in a mixer-settler has proven particularly advantageous. Mixer-settlers typically comprise a continuously operated mixing zone and a continuously operated settling zone, thus allowing the mixing with the aqueous washing solution and the subsequent settling process for phase separation and separation of the purified silicon-rich fraction to be carried out in a continuous process.

[0057] Particularly suitable washing processes for the Si-rich fraction are known from WO 2023 / 041680 A1.

[0058] The silicon-rich fraction and the phosphorus-rich fraction can be mixed before processing in the FCC unit, so that a mixture containing both fractions is processed in the FCC unit. Alternatively, the silicon-rich fraction and the phosphorus-rich fraction can also be processed separately in the FCC unit. In a preferred embodiment, the silicon-rich fraction and / or the phosphorus-rich fraction is mixed with another hydrocarbon stream before processing in the FCC unit. This is particularly advantageous because the silicon-rich fraction and / or the phosphorus-rich fraction can then be processed as a co-feed in an existing FCC process.

[0059] In the context of the process according to the invention, processing in an FCC unit is preferably understood as contacting the hydrocarbons with an FCC catalyst at a temperature of at least 400 °C, preferably at least 450 °C, more preferably at least 480 °C, wherein hydrocarbons contained preferably in the silicon-rich fraction and / or the phosphorus-rich fraction are cracked, i.e., preferably longer hydrocarbon chains are converted into shorter hydrocarbon chains. The contacting preferably takes place in a fluidized bed reactor. The FCC catalyst is preferably a silicate or an aluminate, and particularly preferably a zeolite.

[0060] In a preferred embodiment, the FCC unit comprises a catalyst consisting of zeolites. As explained above, zeolites are particularly well suited for the removal of Si and P according to the inventive process, since the free Si=O or Si-OH groups of the catalyst can react with Si and / or P groups, whereby the catalyst can grow by the respective number of Si or P atoms from the impurities. The organic residue of organic Si and P compounds can be removed under FCC conditions.

[0061] Zeolites modified with phosphate groups are particularly preferred as catalysts. The zeolites can also be modified with rare earth elements. For example, the catalyst could be zeolite Y.

[0062] Preferably, the FCC unit has a riser nozzle. A riser nozzle particularly facilitates the introduction of lighter fractions into the FCC unit. Preferably, the silicon-rich fraction and the phosphorus-rich fraction are introduced into the FCC unit via separate riser nozzles. This simplifies the processing of fractions with different boiling ranges.

[0063] Preferably, the FCC product comprises ethylene and / or propylene.

[0064] In a preferred embodiment, the hydrocarbon stream is a synthetic crude oil stream. In the context of the invention, a "synthetic crude oil stream" is preferably understood to be a stream containing synthetic crude oil or a fraction thereof. Preferably, the synthetic crude oil stream consists of synthetic crude oil or a fraction thereof. Within the scope of the invention, it is particularly preferred if the synthetic crude oil stream includes, and especially consists of, a pyrolysis oil or a fraction thereof. Preferably, the pyrolysis oil is a pyrolysis oil obtained from biomass, especially wood, and / or plastic.As mentioned at the outset, pyrolysis oils from biomass or wood can already contain organic phosphorus compounds of natural origin (such as phospholipids and nucleic acids) and often also exhibit silicon and phosphorus compounds in the form of impregnations and surface treatments (such as flame retardants, surface enhancements by silicones, silicone adhesives, etc.). The process according to the invention has proven particularly suitable when the synthetic crude oil stream is a hydrocarbon mixture obtained from the depolymerization of biomass or plastic material, especially plastic material. Preferably, the synthetic crude oil stream is therefore a plastic pyrolysate or a fraction thereof, or a biomass, especially wood, pyrolysate, or a fraction thereof. However, the process according to the invention is also well suited for other synthetic crude oils and fractions thereof.In further preferred embodiments, the synthetic crude oil stream therefore contains shale oil or upgraded bitumen, preferably it consists of these.

[0065] In a particularly preferred embodiment, the synthetic crude oil stream is therefore produced by depolymerization of plastic material, especially plastic waste. Those skilled in the art are familiar with the production of a synthetic crude oil stream by depolymerization of plastic material. Such processes are known, for example, from WO 2012 / 149590 A1 and US 6,060,631 A. Preferably, the plastic material comprises polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyamide (PA), styrene-acrylonitrile (SAN), and / or acrylonitrile butadiene styrene (ABS).

[0066] In a preferred embodiment, the plastic material comprises silicon compounds, preferably organic silicon compounds, and preferably silicones, in particular polyorganosiloxanes. Silicones typically contain O-Si(CH₃)-O dimethylsiloxane units. Silicones (oils and plastics) are typically produced industrially from dimethyldichlorosilane or via cyclic siloxanes (e.g., octamethylcyclotetrasiloxane). For stability reasons, cyclic siloxanes can be regenerated from the straight-chain silicone by pyrolysis. These cyclic siloxanes have the property of binding to inorganic SiO₂ units via ring opening. This reaction is favored by the conditions in an FCC unit, in particular by elevated temperatures and a formally acidic environment. The dimethyl groups can be cleaved in the FCC process, which can lead to the formation of SiO₂ with the release of CO₂.

[0067] In a preferred embodiment, the silicon content in the plastic material is at least 1 ppm, preferably at least 10 ppm, more preferably at least 100 ppm, even more preferably at least 1000 ppm, and still more preferably at least 10,000 ppm. Preferably, the silicon content is between 1 ppm and 10,000 ppm, more preferably between 5 ppm and 1,000 ppm, and more preferably between 10 ppm and 100 ppm. The silicon content in the plastic material is preferably determined according to ASTM D7111-16(2021).

[0068] Preferably, the silicon content from organic silicon compounds, in particular from silicones, in the plastic material is at least 1 ppm, preferably at least 10 ppm, more preferably at least 100 ppm, even more preferably at least 1000 ppm, and still more preferably at least 10,000 ppm. More preferably, the silicon content is between 1 ppm and 10,000 ppm, more preferably between 5 ppm and 1,000 ppm, and more preferably between 10 ppm and 100 ppm. The silicon content from organic silicon compounds or from silicones refers to the concentration of silicon in the plastic material that is present as part of organic compounds or silicones, respectively. The determination can be carried out, for example, by manually separating the plastic material. If, for instance, the silicon content from organic silicon compounds is to be determined, inorganic silicon sources (filler material, glass, etc.) can be included in a sample of the plastic material.The silicon content of silicones can be removed manually, and the silicon content in the remaining material can be determined using ASTM D7111-16(2021) and extrapolated to the total weight of the sample. If the silicon content of silicones is to be determined, the same procedure can be used: all silicon-containing components except silicones can be removed from a sample, and the silicon content in the remaining material can be determined using ASTM D7111-16(2021) and extrapolated to the total weight of the sample.

[0069] In a preferred embodiment, the plastic material contains phosphorus compounds, preferably organic phosphites, more preferably triarylphosphites. As described above, triarylphosphites are frequently used as additives in plastics, e.g., as flame retardants. Triarylphosphites, or the triaryl phosphates formed from them during pyrolysis, can be removed particularly efficiently using the process according to the invention.

[0070] Unless otherwise indicated, all parameters mentioned herein refer to SATP conditions according to IUPAC ("Standard Ambient Temperature and Pressure"), in particular to a temperature of 25 °C and a pressure of 101,300 Pa.

[0071] All percentage figures (%) herein refer to weight percentages unless otherwise indicated.

[0072] Unless otherwise indicated, all values ​​expressed in "ppm" herein refer to parts per million by mass (ppmw). 1 ppm as used herein is equal to 0.0001 wt.%.

[0073] The person responsible is familiar with the determination of Si and P contents in hydrocarbon streams. Unless otherwise indicated, all Si and P contents specified herein are preferably determined according to ASTM D7111-16(2021).

[0074] The expert is also familiar with the determination of boiling ranges of hydrocarbon fractions. Unless otherwise indicated, all boiling ranges specified herein are determined in accordance with ISO 3924:2019, preferably by Method A or Method B as defined in that standard.

[0075] The present invention is illustrated by the following figure and the following examples, to which it is of course not limited.

[0076] Figure 1 shows a process flow diagram of a preferred embodiment of the method according to the invention.

[0077] In the Figure 1In the illustrated embodiment, a silicon- and phosphorus-containing hydrocarbon stream 1 is generated by the depolymerization of plastic material. The plastic material is compacted, degassed, and melted in an extruder 2. The plastic melt exiting the extruder 2 is mixed in a static mixer 3 with an external solvent 4, preferably heavy oil, and / or with pre-cracked plastic material, which is recycled as a stream 5, to reduce the viscosity of the plastic melt. The resulting mixture is introduced into a depolymerization reactor 6, in which the plastic material is depolymerized, preferably at a temperature between 350 °C and 450 °C. The pyrolysis product obtained is a silicon- and phosphorus-containing hydrocarbon stream 1, which is fed to a hydrocyclone 7 downstream of the pyrolysis reactor 6.In hydrocyclone 7, the hydrocarbon stream 1 is separated into a light stream 8, the recycling stream 5, and a phosphorus-rich fraction 9. A suitable hydrocyclone 8 for this purpose is described, for example, in WO 2023 / 036751 A1.

[0078] The phosphorus-rich fraction 9 can have a boiling range with a lower end of 400 °C and a phosphorus content of at least 10 ppm. In the illustrated embodiment, the phosphorus-rich fraction is subjected to a solids removal process. The phosphorus-rich fraction 9 is fed to a cooling unit 11 to cool it to a temperature in the range of 80 to 240 °C. Subsequently, a solvent 13 comprising at least 20 wt% of an aliphatic hydrocarbon is added to the phosphorus-containing fraction 9 in a container 12 to form a mixture 14. The mass ratio of the phosphorus-rich fraction to the solvent is in the range of 1:1 to 1:3. The container 12 is heated. Wax contained in the phosphorus-rich fraction 9 is dissolved in the solvent at a temperature in the range of 80 to 240 °C, which facilitates the separation of the solids contained in the phosphorus-rich fraction 9.In a separation device 15, which includes a filter, the solids 16 are at least partially separated from the mixture 14 and removed. An evaporator 17 is connected downstream of the separation device 15, enabling the separation of a portion of the solvent 13 used and the return of the separated solvent 18 to the container 12. The solids-depleted, phosphorus-rich fraction 19 is fed to an FCC unit 20.

[0079] The light stream 8 from the hydrocyclone 7 is separated in a column 21 into a gas stream 22, a naphtha fraction 23, and a silicon-rich fraction 24. The naphtha fraction 23 can have a boiling range with an upper limit of 160 °C and can, for example, be further processed in a naphtha hydrotreating plant. The silicon-rich fraction 24 can have a boiling range with a lower limit of 160 °C and an upper limit of 240 °C and a silicon content of at least 10 ppm. In the embodiment shown, the silicon-rich fraction 24 is washed in the FCC unit 20 before processing. The silicon-rich fraction 24 is mixed with an aqueous washing solution 25 in a mixing zone of a mixer-settler 26, preferably in a volumetric mixing ratio of 1:1 and at a temperature of at least 40 °C. The aqueous washing solution is preferably aqueous sulfuric acid with a pH value of less than 7.In a settling zone of the mixer-settler 26, a purified oil phase is separated from a water phase. The water phase is removed as wastewater stream 27. The oil phase, as a washed Si-rich fraction 28, is fed to the FCC unit 20.

[0080] The washed Si-rich fraction 28 and the solids-depleted P-rich fraction 19 are processed in the FCC unit 20 and converted into a Si- and P-poor FCC product 29. Example 1: Removal of Si and P compounds using FCC

[0081] The influence of high silicon and phosphorus contents on FCC processes was investigated. For this purpose, a vacuum gas oil was used as the hydrocarbon stream to be processed. Either 10,000 ppm (= 1 wt%) of silicone oil or 10,000 ppm (= 1 wt%) of tris(2,4-di-tert-butylphenyl)phosphite was added to the vacuum gas oil. The resulting mixtures were processed in an FCC system, and the FCC products were analyzed for their silicon and phosphorus content according to ASTM D7111-16(2021).

[0082] The following results were obtained: FCC deployment P in the FCC product Si in the FCC product Vacuum gas oil < 1 ppm < 1 ppm Vacuum gas oil + 10000 ppm Tris(2,4-di-tert-butylphenyl)phosphite < 1 ppm 7.7 ppm Vacuum gas oil + 10000 ppm silicone oil < 1 ppm 1.6 ppm

[0083] These results demonstrate that even with an overdose of Si and P compounds (10,000 ppm), the FCC process can still be successfully carried out, yielding a product with low Si and P content. Both Si and P are virtually completely removed; the small amounts of Si observed in some cases are not due to the silicone oil used, but rather to catalyst fines, as evidenced by their presence even in the experiment without silicone oil. This shows that Si and P compounds can be efficiently removed by treatment in an FCC unit. Example 2: Si and P concentrations in boiling sections from synthetic crude oil

[0084] Experiments were conducted to investigate which boiling points in synthetic crude oils exhibit particularly high Si and P concentrations and are therefore advantageously suited for processing in an FCC unit. For this purpose, pyrolysis oils were produced from various waste plastics (silicone additives, pyrolysis of plastics from the electronics industry, real mixtures from sorting facilities, residual waste sorting, etc.) and separated by subsequent distillation for pilot plant trials. The pyrolysis was carried out as described in the section on Figure 1 The described procedure was carried out. The Si and P content in the individual boiling points was determined according to the standard ASTM D7111-16(2021).

[0085] The following tables show the results of two separate distillations with a pyrolysis oil from a plastic waste sorting process: Attempt 1: Faction (boiling area) P [ppm] Si [ppm] Naphtha SB-175 °C 1,8 9,8 Kerosene 175-225 °C 1 22,5 Gas oil 225-350 °C 0,5 5,2 Spindle oil 350-410 °C 0, 8 2,1 +410 °C 32,1 1,2 Attempt 2: Faction (boiling area) P [ppm] Si [ppm] Naphtha SB-175 °C 1,2 7,2 Kerosene 175-225 °C 0, 9 21,3 Gas oil 225-350 °C 0, 6 4,5 Spindle oil 350-410 °C 2, 9 2,4 +410 °C 30,4 1

[0086] The results of these experiments show that the silicon concentrations are highest in the kerosene fractions with boiling ranges in the range of 175 to 225 °C. The phosphorus concentrations are highest in the heavier fractions, especially with boiling ranges above 410 °C.

Claims

1. A process for processing a phosphorus (P)-containing hydrocarbon stream (1), the process comprising the following steps: - providing the hydrocarbon stream (1); - separating a P-rich fraction (9) from the hydrocarbon stream (1), wherein the P-rich fraction (9) has a boiling range with a lower end of at least 350 °C and a P content of at least 10 ppm; - processing the P-rich fraction (9) in a fluid catalytic cracking (FCC) unit (20).

2. The process according to claim 1, wherein the P-rich fraction (9) is subjected to solids depletion prior to processing in the FCC unit (20).

3. The process according to claim 2, wherein the solids depletion comprises the following steps: - adding a solvent (13) to the P-rich fraction (9) to form a mixture (14); - separating solids (16) from the mixture (14).

4. The process according to claim 3, wherein the solvent (13) comprises at least 20 wt.% of an aliphatic hydrocarbon, based on the total weight of the solvent (13).

5. The method according to claim 3 or 4, wherein the mixture (14) has a temperature of at least 80 °C.

6. The method according to any one of claims 3 to 5, wherein after separating the solids (16) from the mixture (14), at least a portion of the solvent (13) is separated from the mixture (14).

7. The method according to claim 6, wherein at least a portion of the separated solvent (18) is reused for solids depletion.

8. The process according to any one of claims 1 to 6, wherein the hydrocarbon stream (1) is a phosphorus (P) and silicon (Si)-containing hydrocarbon stream (1), wherein, in addition to the P-rich fraction (9), an Si-rich fraction (24) is separated from the hydrocarbon stream (1), wherein the Si-rich fraction (24) has a boiling range with a lower end of at least 120 °C and a Si content of at least 10 ppm; and wherein the P-rich fraction (9) and the Si-rich fraction (24) are processed in the FCC unit (20).

9. The process according to claim 8, wherein the Si-rich fraction (24) has a boiling range with an upper end of at most 280 °C.

10. Process according to claim 8 or 9, wherein a naphtha fraction (23) is separated from the hydrocarbon stream (1) in addition to the Si-rich fraction (24), preferably wherein the naphtha fraction (23) has a boiling range with an upper end of at most 200 °C.

11. The method according to any one of claims 8 to 10, wherein the Si-rich fraction (24) is washed with at least one aqueous washing solution (25) prior to processing in the FCC unit (20).

12. The method according to claim 11, wherein the washing with the at least one aqueous washing solution (25) takes place at a temperature of at least 40 °C.

13. The method according to claim 11 or 12, wherein the pH of the aqueous washing solution (25) is less than 8.

14. The process according to any one of claims 1 to 13, wherein the FCC unit (20) comprises a catalyst comprising zeolites.

15. The process according to any one of claims 1 to 14, wherein the hydrocarbon stream (1) is produced by depolymerization of plastic material, in particular plastic waste.

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