EP4520803A1 - Method for processing a phosphorus-containing hydrocarbon stream - Google Patents

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

The present invention relates to processes for processing a phosphorus (P)-containing hydrocarbon stream.

Refinery processes involve material streams of various origins, which may be contaminated with various contaminants. Silicon (Si) and phosphorus (P) play an important role. For example, material streams can be contaminated by silicone oils used as lubricants and sealants in refinery plants. Silicone oils are also sometimes used as process additives or antifoam agents, for example, in cokers or thermal gasoil units (TGUs). P compounds are also frequently used as additives, for example, as corrosion inhibitors, which can result in P-containing contaminants.

Such contaminants are particularly significant in connection with synthetic crude oils. Synthetic crude oil, sometimes also referred to as syncrude, can be obtained from a variety of processes. For example, synthetic crude oil can be shale oil, which is extracted from oil shale by pyrolysis. Another source is hydrocarbons extracted from oil sands, particularly bitumen, which can be upgraded to produce synthetic crude oil. Furthermore, synthetic crude oil can also be produced from plastic material, such as plastic waste, through cracking. Another source of synthetic crude oils is biomass, wood, and other biological raw materials, which may already contain organic P compounds from their natural origin (such as phospholipids and nucleic acids) and to which Si and P compounds are often added in the form of impregnations and surface treatments (such as flame retardants, surface enhancements using silicones, silicone adhesives, etc.). Synthetic crude oils typically contain various impurities that can have adverse effects on refining processes and refinery facilities, or even render the crude oil completely unsuitable for certain refining processes. The type and content of these impurities can vary greatly depending on the source and method used to extract the synthetic crude oil. However, Si and P play an important role.

Si and P can cause problems in connection with various processes in refinery plants. For example, Si- and P compounds, for example, can be harmful to catalysts in hydrogenation plants and lead to vitrification. Therefore, Si and P typically have to be removed prior to such a process. Separation is usually achieved using complex guard beds. However, guard beds incur ongoing costs and must be replaced regularly, which in turn requires plant shutdown. When using large quantities of hydrocarbon streams, guard beds quickly become overloaded even at low Si or P contents and must be replaced frequently.

There is therefore a need for new and improved processes for utilizing Si- and/or P-containing hydrocarbon streams. It is an object of the present invention to provide such processes.

• Bereitstellen des Kohlenwasserstoffstroms;
• Abtrennen einer P-reichen Fraktion vom Kohlenwasserstoffstrom, wobei die P-reiche Fraktion einen Siedebereich mit einem unteren Ende von mindestens 350 °C und einen P-Gehalt von mindestens 10 ppm aufweist;
• Verarbeiten der P-reichen Fraktion in einer Fluid Catalytic Cracking (FCC)-Einheit.

The present invention therefore relates to a process for processing a phosphorus (P)-containing hydrocarbon stream, the process comprising the following steps:

• Providing the hydrocarbon stream;
• separating a P-rich fraction from the hydrocarbon stream, the P-rich fraction having 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 in a Fluid Catalytic Cracking (FCC) unit.

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, an 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.

Until now, the state of the art has generally assumed that impurities must be removed from hydrocarbon streams prior to refinery processes such as FCC. WO 2021/201932 A1 a process for the pyrolysis of plastic waste, whereby the entire liquid fraction from is fed into an FCC unit for pyrolysis. It is expressly pointed out that impurities - including numerous other P compounds and silica - in plastic waste must be removed to below 5 ppm if possible ( WO 2021/201932 A1 , [0036]). If this is not achieved, a separate guard bed must be provided to remove the impurities ( WO 2021/201932 A1 , [0037]). In addition, a pretreater unit can be provided before the FCC unit to remove sulfur, nitrogen, phosphorus, silica, dienes and metals ( WO 2021/201932 A1 , [0014]).

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

Without being bound to any theory, the inventors explain this by saying that during the FCC process any organic components of Si and P compounds are cleaved, formally forming SiO ₂ or PO ₄ ^3- groups. In contrast to hydrogenation plants, in which the uppermost catalyst layer can vitrify, the SiO ₂ or PO ₄ ^3- groups do not harm the FCC process. Instead, they can even expand the basic framework of FCC catalysts. In FCC processes, zeolites, which consist of a silicate framework and which can be modified with phosphate groups in the active center, are regularly used as catalysts. In the opinion of the inventors, the SiO ₂ or PO ₄ ^3- groups formed during the process can attach themselves to existing catalysts and subsequently act as catalysts themselves or at least not negatively influence the catalyst activity. This effect is particularly beneficial when a zeolite is already used as the starting catalyst; However, the use of other catalysts is also possible.

In the context of the invention, "P-containing" preferably a P content of at least 0.1 ppm, preferably at least 1 ppm, in particular at least 10 ppm.

The hydrocarbon stream preferably contains organic P compounds, 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, for example, from the depolymerization of plastic can contain significant amounts of triarylphosphites and/or triaryl phosphates. It is therefore also preferred if the hydrocarbon stream is produced from the depolymerization of plastic material containing triarylphosphites. The triarylphosphites are preferably tris(2,4-di-tert-butylphenyl)phosphite, trisphenyl phosphite, and/or tristolyl phosphite. 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 P compounds, in particular of the said preferred organic P compounds, in the hydrocarbon stream is at least 0.1 ppm, preferably at least 1 ppm, in particular at least 10 ppm.

Preferably, the P-rich fraction has a P 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 P content is between 10 and 10,000 ppm, more preferably between 15 and 2,000 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.

Preferably, a P-poor FCC product is obtained by processing the P-rich fraction in the FCC unit.

"P-poor" herein preferably means a lower P content than "P-rich," i.e., the P-poor FCC product has a lower P content than the P-rich fraction. Preferably, the P-poor FCC product has a P content of less than 10 ppm, preferably less than 5 ppm, more preferably less than 1 ppm, more preferably less than 0.5 ppm.

Within the scope of the invention, it has been shown that P compounds can typically be present in particular in hydrocarbon fractions with boiling ranges above 350°C. This also applies in particular to the above-mentioned triarylphosphites and triarylphosphates. If the P-rich fraction has a boiling range with a lower end of at least 350°C, a large proportion of the P compounds can therefore be separated from the hydrocarbon stream without, however, entraining valuable lighter fractions with boiling ranges below 350°C. These lighter fractions can therefore advantageously be utilized elsewhere. It is therefore preferred if the P-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.

On the other hand, to ensure that the most important P compounds are separated with the P-rich fraction, it is also advantageous if the lower end of the boiling range of the P-rich fraction is not too high. Therefore, the lower end of the boiling range is preferably between 350°C and 500°C, 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, more preferably between 400°C and 420°C.

In embodiments of the process according to the invention, it is also preferred if the P-rich fraction has a boiling range with an upper end 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, more preferably at most 500 °C. Preferably, the upper end of the boiling range is between 450 °C and 1000 °C, more preferably between 500 °C and 900 °C, more preferably between 600 °C and 800 °C. By providing a boiling range with a lower and an upper end as indicated, those fractions containing the most important P compounds can be selectively cut out of the hydrocarbon stream.

Within the scope of the invention, it has proven advantageous if the P-rich fraction is subjected to a solids depletion prior to processing in the FCC unit. Preferably, the solids-depleted P-rich fraction is therefore processed in the FCC unit. It has been shown that the P-rich fraction can often 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 subsequently in the P-rich fraction.

Solids depletion is preferably understood herein to mean a reduction in the solids content. Preferably, the solids content of the P-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.%, even more preferably less than 0.1 wt.%. The solids content is preferably determined according to ASTM D5631-21.

Solids depletion can occur before or after the separation of the P-rich fraction from the hydrocarbon stream, i.e., the P-rich fraction can also undergo solids depletion as part of the hydrocarbon stream. Additional steps can also occur between solids depletion and the processing of the P-rich fraction in the FCC unit, e.g., additional fractions can also be separated from the solids-depleted P-rich fraction.

To avoid negative impacts on the FCC process and the FCC catalyst To minimize P-rich fractions, it is preferred that the P-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.%, more preferably less than 0.01 wt.%. The ash content can preferably be determined according to ISO 6245:2002.

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

In a preferred embodiment, the solids depletion comprises the following steps: adding a solvent to the P-rich fraction to form a mixture; separating solids from the mixture. The addition of a solvent to the P-rich fraction has the advantage that waxes present in the P-rich fraction can be at least partially dissolved in the solvent and thus can be particularly well separated from the undesired solids.

The solvent can be added to the P-rich fraction using an introduction device. The introduction device can have a dosing device, such as a dosing pump. For the addition of the solvent, the P-rich fraction can be fed to a container to which the introduction device can be connected. The container can be heated so that the wax contained in the P-rich fraction can dissolve in the solvent at a specific temperature.

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, even more preferably at least 160°C. When the mixture has such a high temperature, waxes present in the P-rich fraction can be dissolved even better and solids can be removed even more efficiently. In particular, it is preferred if the mixture has a temperature in the range of 80 to 240 °C, more preferably 100 to 160 °C, even more preferably 100 to 140 °C.

The mixture can preferably be subjected to a pressure in the range of 1 to 25 bar, in particular in the range of 5 to 16 bar. This can further improve the process control and achieve rapid dissolution of wax in the solvent.

The solvent may preferably have a boiling point (or boiling range) in the range of 20 to 270°C, more preferably 20 to 250°C, even more preferably 35 to 200°C, and even more preferably 50 to 150°C. This has been proven particularly favorable for the efficient dissolution of wax and also enables efficient subsequent removal 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.

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. %, even more preferably at least 90 wt. %, of an aliphatic hydrocarbon, based on the total weight of the solvent. The solvent preferably consists of an aliphatic hydrocarbon or a mixture consisting of two or more aliphatic hydrocarbons. With an increasing proportion of aliphatic hydrocarbon, not only can the ability of the solvent to dissolve wax improve, but the solubility of solids in the solvent can also be reduced. With a high proportion of aromatics in the solvent, however, certain solids, for example asphaltenes or tar, can partially dissolve in the solvent, which can make separation more difficult.

The aliphatic hydrocarbon is preferably selected from the group of aliphatic hydrocarbons with up to 15 carbon atoms per molecule, especially from 4 to 12 carbon atoms per molecule. N-pentane, n-hexane, n-heptane, isododecane, n-tetradecane, or a mixture thereof have proven particularly suitable.

The mass ratio between the P-rich fraction and the solvent may 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.

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

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, in particular 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.

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

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

In a preferred embodiment, at least a portion of the separated solvent is reused for solids removal. Before being returned to the process, the solvent can preferably be additionally purified, preferably by evaporation, in particular by rotary evaporation.

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, an 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. Preferably, a P- and Si-poor FCC product is obtained from the processing of the P-rich fraction and the Si-rich fraction.

Also disclosed is a process for processing a silicon (Si)-containing hydrocarbon stream, the process 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 above-described process for processing a P-containing hydrocarbon stream.

• Bereitstellen des Kohlenwasserstoffstroms;
• Abtrennen einer P-reichen Fraktion vom Kohlenwasserstoffstrom, wobei die P-reiche Fraktion einen Siedebereich mit einem unteren Ende von mindestens 350 °C und einen P-Gehalt von mindestens 10 ppm aufweist;

• Abtrennen einer Si-reichen Fraktion vom Kohlenwasserstoffstrom, wobei die Si-reiche Fraktion einen Siedebereich mit einem unteren Ende von mindestens 120 °C und einen Si-Gehalt von mindestens 10 ppm aufweist;
• Verarbeiten der P-reichen Fraktion und der Si-reichen Fraktion in einer Fluid Catalytic Cracking (FCC)-Einheit.

A preferred embodiment relates to a process for processing a phosphorus (P) and silicon (Si)-containing hydrocarbon stream, the process comprising the following steps:

• Providing the hydrocarbon stream;
• Separating a P-rich fraction from the hydrocarbon stream, wherein the P-rich fraction has a boiling range with a lower end of at least 350 °C and a P content of at least 10 ppm;

• Separating a Si-rich fraction 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;
• Processing the P-rich fraction and the Si-rich fraction in a Fluid Catalytic Cracking (FCC) unit.

Preferably, a P-poor and Si-poor FCC product is obtained from processing the P-rich fraction and the Si-rich fraction.

In the context of the invention, "Si-containing" is preferably understood to mean a Si content of at least 0.1 ppm, preferably at least 1 ppm, in particular at least 10 ppm. The hydrocarbon stream preferably 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. The concentration of organic Si compounds, in particular of the aforementioned preferred organic Si compounds, in the hydrocarbon stream is preferably at least 0.1 ppm, preferably at least 1 ppm, in particular at least 10 ppm.

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 10,000 ppm, more preferably between 15 and 2,000 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.

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

"Low Si" herein preferably means a lower Si content than "rich Si," i.e., the low Si FCC product has a lower Si content than the high Si fraction. Preferably, the low Si FCC product has a Si content of less than 10 ppm, preferably less than 5 ppm, more preferably less than 1 ppm, more preferably less than 0.5 ppm.

• Hexamethylcyclotrisiloxan (Siedepunkt: 134-135 °C);
• Octamethylcyclotetrasiloxan (Siedepunkt: 171-175 °C);
• Decamethylcyclopentasiloxan (Siedepunkt: 210 °C);
• Dodecamethylcyclohexasiloxan (Siedepunkt: 245 °C).

Within the scope of the invention, it has been shown that Si compounds can typically be present in particular 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 Si polymers—such as a hydrocarbon stream obtained from the depolymerization of plastic material—the hydrocarbon stream can contain large amounts of cyclic dimethylsiloxanes, which are formed from the Si 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).

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

Therefore, if the Si-rich fraction has a boiling range with a lower end of at least 120°C, a large portion of the Si compounds can be separated from the hydrocarbon stream without, however, entraining valuable lighter fractions with boiling ranges below 120°C. These lighter fractions can therefore advantageously be utilized elsewhere. It is preferred if the Si-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 Si compound to be separated even more specifically and even larger boiling ranges to be utilized for other purposes.

On the other hand, to ensure that the most important Si compounds are separated with the Si-rich fraction, it is also advantageous if the lower end of the boiling range of the Si-rich fraction is not too high. Therefore, the lower end of the boiling range is preferably between 120°C and 230°C, 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, more preferably between 170°C and 180°C.

In embodiments of the process according to the invention, it is further 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. The upper end of the boiling range is preferably 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 providing a boiling range with a lower and an upper end as stated, those fractions containing the most important Si compounds can be specifically removed from the hydrocarbon stream. This applies in particular to the above-mentioned cyclic dimethylsiloxanes. Providing the stated boiling ranges is therefore particularly advantageous when the hydrocarbon stream is a synthetic crude oil stream, in particular a hydrocarbon stream obtained from the depolymerization of plastic material.

In a preferred embodiment of the process according to the invention, a light fraction is separated from the hydrocarbon stream in addition to the Si-rich fraction. The light fraction is preferably a naphtha fraction. The light fraction preferably has a boiling range with an upper end of at most 200 °C, preferably at most 190 °C, more preferably at most 180 °C, more preferably at most 170 °C, more preferably at most 160 °C. The selection of such a boiling range for the light fraction has the advantage that significant Si compounds are generally not present therein, and the light fraction can thus be reused without additional separation of Si compounds, for example as a valuable naphtha fraction, e.g., in a naphtha hydrotreating plant.

In a preferred embodiment, the light fraction has a Si content of less than 20 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, more preferably less than 1 ppm. It is also preferred if the light fraction has a P content of less than 20 ppm, preferably less than 10 ppm, more preferably less than 5 ppm, more preferably less than 1 ppm.

Within the scope of the invention, it has proven advantageous if the Si-rich fraction is washed with at least one aqueous wash solution before processing in the FCC unit. Preferably, the washed Si-rich fraction is therefore processed in the FCC unit. Such washing can remove unwanted compounds that may be present in the Si-rich fraction and that may have negative effects on the FCC unit. For example, hydrocarbon streams often contain basic compounds, e.g. 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 Si-rich fraction. Such basic compounds, in particular amines, can be removed upstream of the FCC unit using an aqueous wash. Washing with the at least aqueous wash solution can take place before or after separating the Si-rich fraction from the The Si-rich fraction can also be scrubbed as part of the hydrocarbon stream, meaning that the Si-rich fraction can also pass through the scrubbing process as part of the hydrocarbon stream. Additional steps can also be performed between the scrubbing of the Si-rich fraction and processing in the FCC unit, for example, additional fractions can be separated from the scrubbed Si-rich fraction.

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

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

Preferably, washing with the at least one aqueous washing solution takes place 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, more preferably at least 70°C. Providing such a high temperature enables particularly thorough removal of the undesired basic compounds. It is particularly preferred if washing takes place at a temperature in the range from 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, even more preferably from 60°C to 80°C.

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

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

The Si-rich fraction and the P-rich fraction can be blended prior to processing in the FCC unit, resulting in a mixture containing the Si-rich fraction and the P-rich fraction being processed in the FCC unit. Alternatively, the Si-rich fraction and the P-rich fraction can also be processed separately in the FCC unit. In a preferred embodiment, the Si-rich fraction and/or the P-rich fraction is blended with another hydrocarbon stream prior to processing in the FCC unit. This is particularly advantageous because the Si-rich fraction and/or the P-rich fraction can thus be processed as co-feed in an existing FCC process.

In the context of the process according to the invention, processing in an FCC unit is preferably understood as contacting 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 present in the Si-rich fraction and/or in the P-rich fraction are preferably cracked, i.e., longer hydrocarbon chains are preferably 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.

In a preferred embodiment, the FCC unit comprises a catalyst comprising zeolites. As explained above, zeolites are particularly suitable for the removal of Si and P according to the process of the invention, since the free Si=O and 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.

Particularly preferred catalysts are zeolites modified with phosphate groups. The zeolites can also be modified with rare earth elements. For example, the catalyst can be zeolite Y.

Preferably, the FCC unit has a riser nozzle. A riser nozzle, in particular, enables the improved introduction of lighter fractions into the FCC unit. Preferably, the Si-rich fraction and the P-rich fraction are introduced into the FCC unit via separate riser nozzles. This facilitates the processing of fractions with different boiling ranges.

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

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 mean a material stream containing a synthetic crude oil or a fraction of a synthetic crude oil. The synthetic crude oil stream preferably 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 comprises, in particular consists of, a pyrolysis oil or a fraction thereof. The pyrolysis oil is preferably a pyrolysis oil obtained from biomass, in particular wood, and/or plastic. As mentioned above, pyrolysis oils from biomass or wood can already contain organic P compounds of natural origin (such as phospholipids and nucleic acids) and frequently also contain Si and P compounds in the form of impregnations and surface treatments (such as flame retardants, surface improvement with silicones, silicone adhesives, etc.). The process according to the invention has proven to be particularly suitable when the synthetic crude oil stream is a product obtained from the depolymerisation of biomass or plastic material, in particular Plastic material, is a hydrocarbon mixture obtained. The synthetic crude oil stream is therefore preferably a plastic pyrolysate or a fraction thereof, or a biomass, in particular 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 comprises shale oil or upgraded bitumen, preferably consisting thereof.

In a particularly preferred embodiment, the synthetic crude oil stream is therefore produced by depolymerization of plastic material, in particular plastic waste. The person skilled in the art is 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 the US 6,060,631 A The plastic material preferably comprises polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyamide (PA), styrene-acrylonitrile (SAN) and/or acrylonitrile-butadiene-styrene (ABS).

In a preferred embodiment, the plastic material comprises Si compounds, preferably organic Si compounds, preferably silicones, in particular polyorganosiloxanes. Silicones typically contain O-Si(CH ₃ )-O dimethylsiloxane units. Silicones (oils and plastics) are typically produced industrially from dimethyldichlorosilane or via cyclic siloxanes (e.g. octamethylcyclotetrasiloxane). For reasons of stability, pyrolysis can convert the straight-chain silicone back into cyclic siloxanes. These have the property of bonding to inorganic SiO ₂ units by 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 SiO ₂ with the elimination of CO ₂ .

In a preferred embodiment, the Si 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, even more preferably at least 10000 ppm. Preferably, the Si content is between 1 ppm and 10,000 ppm, preferably between 5 ppm and 1,000 ppm, and more preferably between 10 ppm and 100 ppm. The Si content in the plastic material is preferably determined according to ASTM D7111-16 (2021).

The Si content from organic Si compounds, in particular from silicones, in the plastic material is preferably at least 1 ppm, preferably at least 10 ppm, more preferably at least 100 ppm, even more preferably at least 1000 ppm, even more preferably at least 10,000 ppm. The Si content is preferably between 1 ppm and 10,000 ppm, preferably between 5 ppm and 1000 ppm, more preferably between 10 ppm and 100 ppm. The Si content from organic Si compounds or from silicones refers to the concentration of Si in the plastic material that is present as part of organic compounds or silicones. The determination can be carried out, for example, by manually separating the plastic material. For example, if the Si content of organic Si compounds is to be determined, inorganic Si sources (filler material, glass, etc.) can be manually removed from a sample of the plastic material, and the Si content in the remaining material can be determined using ASTM D7111-16(2021) and extrapolated to the total weight of the sample taken. If the Si content of silicones is to be determined, a similar procedure can be followed by removing all Si-containing components except silicones from a sample, determining the Si content in the remaining material using ASTM D7111-16(2021) and extrapolating it to the total weight of the sample taken.

In a preferred embodiment, the plastic material comprises P compounds, preferably organic phosphites, more preferably triarylphosphites. As explained above, triarylphosphites are frequently used as additives in plastics, e.g., as flame retardants. Triarylphosphites or the triaryl phosphates formed therefrom during pyrolysis can be removed particularly efficiently using the process according to the invention.

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.

All percentages (%) herein refer to weight percentages unless otherwise indicated.

Unless otherwise indicated, "ppm" refers to parts per million on a mass basis (ppmw). 1 ppm, as used herein, corresponds to 0.0001 wt%.

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

The person skilled in the art is also familiar with the determination of boiling ranges of hydrocarbon fractions. Unless otherwise indicated, all boiling ranges stated herein are determined according to ISO 3924:2019, preferably according to Method A or Method B as defined in this standard.

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

Figure 1 shows a process flow diagram of a preferred embodiment of the process according to the invention.

In the Figure 1 In the embodiment shown, a hydrocarbon stream 1 containing Si and P is produced by depolymerizing plastic material. The plastic material is compacted, degassed, and melted in an extruder 2. The plastic melt emerging from the extruder 2 is mixed in a static mixer 3 with an external solvent 4, preferably heavy oil, and/or with already cracked plastic material, which is returned as a recycling stream 5, in order 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 hydrocarbon stream 1 containing Si and P, which is fed to a hydrocyclone 7 downstream of the pyrolysis reactor 6. In the hydrocyclone 7, the hydrocarbon stream 1 is separated into a light stream 8, the recycling stream 5 and a P-rich fraction 9. A hydrocyclone 8 suitable for this purpose is, for example, in the WO 2023/036751 A1 described.

The P-rich fraction 9 can have a boiling range with a lower end of 400 °C and a P content of at least 10 ppm. In the embodiment shown, the P-rich fraction is subjected to solids depletion. The P-rich fraction 9 is fed to a cooling unit 11 for cooling to a temperature in the range of 80 to 240 °C. A solvent 13 comprising at least 20 wt. % of an aliphatic hydrocarbon is then added to the P-containing fraction 9 in a container 12 to form a mixture 14. The mass ratio of the P-rich fraction to the solvent is in the range of 1:1 to 1:3. The container 12 is heated. Wax contained in the P-rich fraction 9 is dissolved in the solvent at a temperature in the range of 80 to 240 °C, which facilitates separation of the solids contained in the P-rich fraction 9. In a separation device 15, which includes a filter, the solids 16 are at least partially separated and removed from the mixture 14. An evaporator 17 is connected downstream of the separation device 15, which enables 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, P-rich fraction 19 is fed to an FCC unit 20.

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 Si-rich fraction 24. The naphtha fraction 23 may have a boiling range with an upper end of 160 °C and can be further processed, for example, in a naphtha hydrotreating plant. The Si-rich fraction 24 may have a boiling range with a lower end of 160 °C and an upper end of 240 °C and a Si content of at least 10 ppm. In the embodiment shown, the Si-rich fraction 24 is washed before processing in the FCC unit 20. The Si-rich fraction 24 is mixed with an aqueous wash 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 of less than 7. In a settling zone of the mixer-settler 26, the purified oil phase separated from a water phase. The water phase is removed as wastewater stream 27. The oil phase is fed to the FCC unit 20 as washed Si-rich fraction 28.

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

The influence of high Si and P contents on FCC processes was investigated. 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 plant, and the FCC products were analyzed for their Si and P content according to ASTM D7111-16 (2021).

The following results were obtained: FCC deployment P in FCC product Si in 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

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 the fact that they also occur in the experiment without silicone oil. This demonstrates 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

Experiments were conducted to determine which boiling points in synthetic crude oils exhibit particularly high Si and P concentrations and are therefore advantageous 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 plants, residual waste sorting, etc.) and separated by subsequent distillation for pilot plant experiments. The pyrolysis was carried out as described in connection with Figure 1 The Si and P contents in the individual boiling points were determined according to ASTM D7111-16(2021).

The following tables show the results of two separate distillations with a pyrolysis oil from a plastic waste sorting plant:
Experiment 1: Fraction (boiling range) 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: Fraction (boiling range) 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

The results of these experiments show that Si concentrations are highest in the kerosine fractions with boiling ranges between 175 and 225 °C. P concentrations are highest in the heavy fractions, especially with boiling ranges above 410 °C.

Claims (15)

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). 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). 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); - Separation of solids (16) from the mixture (14). 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). The method according to claim 3 or 4, wherein the mixture (14) has a temperature of at least 80°C. 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). The method according to claim 6, wherein at least a portion of the separated solvent (18) is reused for solids depletion. The method 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), the Si-rich fraction (24) 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 (9) and the Si-rich fraction (24) are processed in the FCC unit (20). A process according to claim 8, wherein the Si-rich fraction (24) has a boiling range with an upper end of at most 280 °C. 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. A process 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). 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. A method according to claim 11 or 12, wherein the pH of the aqueous washing solution (25) is less than 8. The process according to any one of claims 1 to 13, wherein the FCC unit (20) comprises a catalyst comprising zeolites. 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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