Method for purifying synthetic crude oil stream

Abstract

The invention relates to a method for purifying a synthetic crude oil stream (1), comprising the following steps:-providing a synthetic crude oil stream (1), the synthetic crude oil stream (1) containing aromatic compounds; -contacting the synthetic crude oil stream (1) with a carbonyl stream (2) containing at least one carbonyl compound selected from aldehydes and ketones to form a mixture, thereby cross-linking at least a portion of the aromatic compounds to a condensation product; and-separating the condensation product from the mixture to obtain a purified synthetic crude oil stream (3). The invention also relates to a method for producing a purified synthetic crude oil stream (3).

Description

Technical Field

[0001] This invention relates to a method for purifying synthetic crude oil streams. Background Technology

[0002] Synthetic crude oil, sometimes referred to as syncrude, can be obtained through various processes. For example, synthetic crude oil can be shale oil, obtained through the pyrolysis of oil shale. Another source is hydrocarbons derived from oil sands, particularly bitumen, from which synthetic crude oil can be obtained through upgrading. Furthermore, synthetic crude oil can also be produced by cracking plastic materials, such as plastic waste.

[0003] Synthetic crude oil typically contains various impurities that can adversely affect refining processes and systems, or render the crude oil completely unsuitable for certain refining processes. The type and amount of impurities can vary significantly depending on the source and method of obtaining the synthetic crude oil.

[0004] A particularly significant problem in the further processing of synthetic crude oil is the formation of so-called gum. Pyrolysis oils typically contain various compounds that readily form deposits. These deposits can subsequently clog or otherwise damage refining systems, increase cleaning workloads, and shorten system lifespan. Summary of the Invention

[0005] The problem of gum formation associated with synthetic crude oil has not yet been fully resolved. Methods to reduce the tendency of synthetic crude oil to form gums are still needed. Therefore, the object of this invention is to provide a method for reducing gum formation in synthetic crude oil.

[0006] Therefore, the present invention relates to a method for purifying synthetic crude oil streams, the method comprising the following steps:

[0007] – Provide a synthetic crude oil stream containing aromatic compounds;

[0008] – Contacting a synthetic crude oil stream with a carbonyl stream containing at least one carbonyl compound selected from aldehydes and ketones to form a mixture, thereby crosslinking at least a portion of the aromatic compounds into condensation products; and

[0009] – Separate the condensation products from the mixture to obtain a purified synthetic crude oil stream.

[0010] Another aspect of the present invention relates to a method for producing purified synthetic crude oil streams from plastic materials, comprising the following steps:

[0011] – Provide a plastic material, wherein the plastic material contains a carbonyl source;

[0012] – Pyrolysis of a plastic material to obtain a synthetic crude oil stream containing aromatic compounds, wherein at least one carbonyl compound selected from aldehydes and ketones is released from a carbonyl source, and wherein said at least one carbonyl compound crosslinks with at least a portion of the aromatic compounds to form a condensation product; and

[0013] – Separate the condensation products to obtain a purified synthetic crude oil stream.

[0014] It has been found that certain aromatic compounds significantly promote sediment formation in synthetic crude oil. This is particularly true for phenols, heterocyclic aromatics, bicyclic aromatics, tricyclic aromatics, and polycyclic aromatics. For the purposes of this invention, it has been found that these aromatic compounds in synthetic crude oil can be cross-linked by treatment with aldehydes or ketones to form condensation products, which can be easily separated and removed as insoluble solids. Therefore, in the method according to the invention, gum formation can be promoted in a targeted manner, and the "gum" (i.e., the insoluble condensation products) can be separated. Consequently, the purified synthetic crude oil stream has a low aromatic content, making sediment formation less likely, which protects the system, especially the reaction surfaces containing the catalyst.

[0015] Aromatic compounds are preferably present in dissolved form in the synthetic crude oil stream. In the mixture, the aromatic compounds are preferably cross-linked by at least one carbonyl compound to form insoluble condensation products. These products precipitate as insoluble solids and can therefore be easily separated. Thus, spontaneous precipitation of unwanted components can be achieved by treatment with carbonyl compounds. "Condensation product" herein refers to the reaction product of a carbonyl compound and an aromatic compound. The term "reaction product" may also be used as an alternative to "condensation product".

[0016] The aromatic compounds are preferably selected from phenols, heterocyclic aromatics, bicyclic aromatics, tricyclic aromatics, and polycyclic aromatics. Phenolic compounds are particularly preferred. These compounds have a strong tendency to form deposits, and they can be removed particularly effectively using the method according to the invention.

[0017] Next, using formaldehyde (HCHO) as an example of a carbonyl compound, we will demonstrate the possible condensation reactions of phenolic compounds:

[0018]

[0019] In the first step, the reaction with formaldehyde leads to cross-linking of the two phenolic compounds, while simultaneously eliminating water. The reaction product of this first condensation reaction can then react with other starting products and / or reaction products to form polymers. These polymers can precipitate as solids and are easily separated. The reaction can proceed similarly with other aldehydes and ketones.

[0020] For the purposes of this invention, it is particularly preferred that the aromatic compounds be nitrogen-containing heterocyclic aromatics (N-heterocyclic aromatics), especially pyridine and / or indole. These compounds, in addition to forming deposits, have a significant effect on catalysts, particularly deactivating acidic FCC or HDT catalysts due to their basicity. Since N-heterocyclic aromatics generally have higher nucleophilicity than carbocyclic aromatics, they react particularly efficiently with carbonyl compounds and can therefore be removed particularly effectively using the method according to this invention. Consequently, catalysts in refineries can be particularly well protected.

[0021] Here are some examples of possible condensation reactions between indole and formaldehyde:

[0022]

[0023] The dimethyl dimethyl compound shown is insoluble in the synthetic crude oil stream and can therefore be easily removed. The reaction proceeds similarly for other aldehydes and ketones. Of course, condensation reactions can also occur between different types of aromatic hydrocarbons.

[0024] The aromatic content in the synthetic crude oil stream is preferably at least 10% (w / w), more preferably at least 12% (w / w), more preferably at least 14% (w / w), more preferably at least 16% (w / w), more preferably at least 18% (w / w), and more preferably at least 20% (w / w). Preferably, the aromatic content in the synthetic crude oil stream is from 10% (w / w) to 50% (w / w), more preferably from 12% (w / w) to 45% (w / w), more preferably from 14% (w / w) to 40% (w / w), more preferably from 16% (w / w) to 35% (w / w), more preferably from 18% (w / w) to 30% (w / w), and more preferably from 20% (w / w) to 25% (w / w).

[0025] Preferably, the aromatic content of the purified synthetic crude oil stream is lower than that of the synthetic crude oil stream. Therefore, the method of the present invention can reduce the aromatic content. The aromatic content in the purified synthetic crude oil stream is preferably less than 20% (w / w), more preferably less than 18% (w / w), more preferably less than 16% (w / w), more preferably less than 14% (w / w), more preferably less than 12% (w / w), and more preferably less than 10% (w / w). Preferably, the aromatic content in the purified synthetic crude oil stream is at least 1 percentage point (% (w / w)) lower than that in the synthetic crude oil stream (for example, if the aromatic content in the synthetic crude oil stream is 20% (w / w), then the aromatic content in the purified synthetic crude oil stream is preferably 19% (w / w) or lower). Preferably, the aromatic content in the purified synthetic crude oil stream is at least 2 percentage points (% (w / w) lower than that in the synthetic crude oil stream, more preferably at least 3 percentage points (% (w / w) lower).

[0026] The aromatic hydrocarbon content is preferably determined according to ASTM D6591-19. Alternatively, the aromatic hydrocarbon content may also be determined according to ASTM D5134-21.

[0027] It has proven advantageous that the contact between the synthetic crude oil stream and the carbonyl stream is carried out at a temperature of at least 50°C, preferably at least 60°C, more preferably at least 70°C, more preferably at least 80°C, more preferably at least 100°C, and even more preferably at least 120°C. Particularly preferred is that the contact between the synthetic crude oil stream and the carbonyl stream is carried out at a temperature in the range of 50 to 450°C, more preferably 60 to 350°C, more preferably 70 to 250°C, more preferably 80 to 180°C, more preferably 100 to 170°C, and even more preferably 120 to 160°C. Higher temperatures promote the reaction between aromatic compounds and carbonyl compounds, thereby more effectively removing unwanted aromatic compounds.

[0028] In a preferred embodiment, the contact between the synthetic crude oil stream and the carbonyl stream lasts for at least 0.5 minutes, preferably at least 1 minute, more preferably at least 2 minutes, even more preferably at least 5 minutes, and most preferably at least 12 minutes. A longer duration allows for a more complete reaction, thereby further reducing the content of undesirable aromatic compounds. Therefore, a duration between 0.5 and 180 minutes is particularly preferred, preferably between 1 and 120 minutes, more preferably between 2 and 60 minutes, even more preferably between 5 and 30 minutes, and most preferably between 12 and 20 minutes. The duration is preferably the average time from the initial contact between the synthetic crude oil stream and the carbonyl stream to the separation of the condensation product from the mixture to obtain a purified synthetic crude oil stream. If the method is carried out as a continuous process, the duration preferably corresponds to the average residence time in the washing apparatus used (such as a mixing clarifier).

[0029] In a preferred embodiment, the contact between the synthetic crude oil stream and the carbonyl stream takes place in a pressure vessel. Providing a pressure vessel allows for processing at higher pressures and temperatures and can promote the condensation reaction. This is particularly preferred if the carbonyl stream is an aqueous solution and / or if the mixture formed from the synthetic crude oil stream and the carbonyl stream contains water. As described in more detail below, the presence of water can favor the condensation reaction. In this case, providing increased pressure can keep the water in the mixture liquid.

[0030] Preferably, the contact between the synthetic crude oil stream and the carbonyl stream is carried out at a pressure greater than 2 bar, more preferably greater than 3 bar, more preferably greater than 5 bar, even more preferably greater than 7 bar, and most preferably greater than 10 bar. Particularly preferred is that the contact is carried out at a pressure in the range of 2 to 50 bar, preferably 3 to 35 bar, more preferably 5 to 25 bar, even more preferably 7 to 20 bar, and most preferably 10 to 18 bar.

[0031] In a preferred embodiment, the carbonyl stream is an aqueous solution. Among other advantages, it also facilitates condensation reactions between undesirable aromatic compounds and carbonyl compounds. Specifically, the presence of protons and hydroxide ions in water allows for acidic or basic catalysis of the reaction.

[0032] The beneficial effect can be further enhanced or amplified by the addition of an acid or base to the mixture. The more acid or base present, the faster and more efficient the reaction. In a preferred embodiment, the pH of the carbonyl stream is at least 8, more preferably at least 9, more preferably at least 10, more preferably at least 11, and more preferably at least 12. The pH is preferably in the range of 8 to 14, more preferably in the range of 10 to 13. This allows the condensation reaction to undergo effective basic catalysis. In an equally preferred alternative embodiment, the pH of the carbonyl stream is at most 6, more preferably at most 5, more preferably at most 4, more preferably at most 3, and more preferably at most 2. The pH is preferably in the range of 0 to 6, more preferably in the range of 1 to 5. This allows the condensation reaction to undergo effective acidic catalysis.

[0033] In a particularly preferred embodiment of the method according to the invention, the contact between the synthetic crude oil stream and the carbonyl stream is carried out in the presence of an acid or a base, and / or an acid or base is added to the mixture of the synthetic crude oil stream and the carbonyl stream. This is preferably an acidic aqueous solution or an alkaline aqueous solution. Thus, as described above, the desired condensation reaction can be promoted by an acidic or alkaline catalyst.

[0034] For the purposes of the method according to the invention, any type of aldehyde or ketone can be used as the carbonyl compound. Preferably, the at least one carbonyl compound is selected from formaldehyde, acetaldehyde, propionaldehyde, acrolein, butyraldehyde, crotonaldehyde, acetone, methyl ethyl ketone, and / or pentanone.

[0035] It has been shown that it is particularly advantageous if the at least one carbonyl compound is an aldehyde. Without being bound by any theory, the inventors speculate that this is partly because aldehydes are more electrophilic than ketones, and partly because the steric hindrance is lower when the carbonyl group is terminal. Both factors favor the desired reaction with aromatic compounds. Since these factors are most pronounced with formaldehyde, it is particularly preferred if the at least one carbonyl compound is formaldehyde. The overall advantage of aldehydes over ketones, and especially the advantage of formaldehyde, can also be seen from the data in Example 1, where it was found that the reduction in aromatic hydrocarbon content by formaldehyde was more significant than that by acetone.

[0036] The concentration of carbonyl compounds in the carbonyl stream is preferably at least 1% (w / w), more preferably at least 5% (w / w), more preferably at least 10% (w / w), more preferably at least 15% (w / w), more preferably at least 20% (w / w), and more preferably at least 25% (w / w). This concentration is preferably between 1% (w / w) and 100% (w / w), more preferably between 5% (w / w) and 80% (w / w), more preferably between 10% (w / w) and 60% (w / w), and more preferably between 15% (w / w) and 50% (w / w). Using such a high concentration is beneficial for reaction with aromatic compounds contained in the synthetic crude oil stream.

[0037] Based on the total mass of the synthetic crude oil stream and the carbonyl stream, the concentration of the carbonyl compound is preferably at least 0.01% (w / w), more preferably at least 0.02% (w / w), more preferably at least 0.05% (w / w), more preferably at least 0.1% (w / w), and more preferably at least 0.2% (w / w). Based on the total mass of the synthetic crude oil stream and the carbonyl stream, the concentration of the carbonyl compound is preferably from 0.01% (w / w) to 5% (w / w), preferably from 0.02% (w / w) to 2% (w / w), and more preferably from 0.05% (w / w) to 0.5% (w / w).

[0038] In a preferred embodiment, the volumetric mixing ratio between the synthetic crude oil stream and the carbonyl stream is 10:1 to 1:5, more preferably 5:1 to 1:2.5, and even more preferably 1.5:1 to 1:1.5. This mixing ratio has proven to be particularly effective for processing synthetic crude oil streams.

[0039] In a preferred embodiment, the mixture formed from the synthetic crude oil stream and the carbonyl stream has both polar and non-polar phases, with the condensation products primarily present in the polar phase. Preferably, the condensation products are separated from the mixture by separating the polar phase. If the carbonyl stream is an aqueous solution, the polar phase can be an aqueous phase. Therefore, the condensation products can be separated in a particularly simple manner.

[0040] It has been shown that contact with the carbonyl stream and subsequent polar phase separation are particularly advantageous when carried out in a mixer-clarifier. Typically, a mixer-clarifier comprises a continuously operating mixing zone and a continuously operating clarification zone, thus allowing for the mixing of the synthetic crude oil stream with the carbonyl stream in a continuous process, followed by sedimentation processes for separating the phases and purifying the synthetic crude oil stream.

[0041] In an advantageous embodiment, at least a portion of the separated polar phase is recovered and reused as part of the carbonyl stream. It has been found that the separated polar phase typically still contains a significant proportion of unconsumed carbonyl compounds. If the wastewater stream is partially recycled, the carbonyl compounds can thus be better utilized. For example, recycling can include 1 to 25 cycles. This recycling can offer energy advantages, lower costs, and allow for a smaller system size. The proportion of consumed chemicals can be compensated by adding fresh media to the loop.

[0042] In a preferred embodiment of the method according to the invention, the purified synthetic crude oil stream is washed with a washing aqueous solution to obtain a second purified synthetic crude oil stream. This additional washing step allows for a more thorough removal of impurities contained in the synthetic crude oil stream.

[0043] The washing aqueous solution is preferably an acidic washing aqueous solution. In particular, the pH value of the washing aqueous solution is preferably less than 6, more preferably less than 5, more preferably less than 4, and even more preferably less than 3.5. If the pH value of the carbonyl stream is alkaline, such a pH value is particularly preferred. Therefore, after alkaline washing in the form of carbonyl stream treatment, acidic washing can be performed.

[0044] Washing purified synthetic crude oil streams with acidic washes can improve the removal of basic compounds such as amines, pyridines, and other basic impurities. If the carbonyl stream has an alkaline pH, especially if it is an aqueous stream, neutral compounds may have already undergone alkaline hydrolysis by treatment with the carbonyl stream. In this case, additional alkaline hydrolysis products (such as amines) can be removed by acid washing. In particular, polycyclic amines can also be effectively removed by this step. Polycyclic amines are often present in synthetic crude oils, especially in pyrolysis oils. They may form during cracking in the presence of nitrogen sources such as additives or polymers, such as polyamide (PA), polyacrylonitrile (PAN), or acrylonitrile-butadiene-styrene copolymer (ABS). Polycyclic amines can be, for example, polycondensed—saturated, monounsaturated and polyunsaturated, or aromatic ring systems. They may be partially dissolved in the synthetic crude oil or suspended in colloidal regions, often leading to unwanted deposits that make the system difficult to clean. Furthermore, they can also cause laying on the active surfaces of catalysts in subsequent applications. Furthermore, they can dissolve unwanted compounds in the organic product phase, such as salts, chlorides, heavy metals, or sulfides. It has been demonstrated that polycyclic amines can be effectively removed by an acidic washing step. For the removal of polycyclic amines, an acidic washing step at a temperature of at least 20°C has proven advantageous. Removal is particularly effective at a temperature of at least 50°C.

[0045] However, it has been found that it is advantageous if the temperature during the acid washing step is not too high, particularly below the temperature at which the carbonyl stream contacts. It has been demonstrated that high temperatures during the acid washing step lead to reduced product yield and impurity formation. Therefore, performing the acid washing step at temperatures below 120°C has proven advantageous. In particular, these adverse effects can be minimized if the temperature is below 100°C, or even more preferably below 95°C.

[0046] Another advantage of the lower temperature in the acid washing step is that it significantly reduces the material requirements for the washing apparatus. At high temperatures in the presence of acidic solutions, special materials or coatings are typically required, leading to a substantial increase in cost. In a preferred embodiment, the washing of the purified synthetic crude oil stream with the acidic washing solution is therefore carried out at a temperature lower than the temperature at which the synthetic crude oil stream contacts the carbonyl stream.

[0047] In a preferred embodiment, the washing aqueous solution contains sulfuric acid. The concentration of sulfuric acid is preferably between 0.5% and 10% (w / w), particularly between 1% and 5% (w / w).

[0048] It has proven advantageous to use a volumetric mixing ratio of 10:1 to 1:5 between the purified synthetic crude oil stream and the washing aqueous solution, preferably 5:1 to 1:2.5, and even more preferably 2.5:1 to 1:1.5. Such a mixing ratio is particularly effective in removing alkaline impurities.

[0049] The method according to the invention may further include a washing step. For example, the purified synthetic crude oil stream may undergo a further washing or purification step before washing with a washing aqueous solution. However, it is preferred that no further purification step, particularly no washing step, filtration step, and / or hydrogenation treatment step, is performed between the separation of condensation products to obtain the purified synthetic crude oil stream and the washing of the purified synthetic crude oil stream with a washing aqueous solution. Among other advantages, this also has the advantage that the basic products generated by alkaline hydrolysis of neutral compounds can be removed in a preferred acidic washing step immediately following the alkaline washing step.

[0050] In another preferred embodiment of the method according to the invention, the second purified synthetic crude oil stream is washed with an additional washing aqueous solution to obtain a third purified synthetic crude oil stream. This additional washing step allows for particularly thorough removal of impurities that may still remain after the acid washing step.

[0051] In this context, it is particularly preferred that the pH range of the additional washing aqueous solution is 3 to 13, preferably 4 to 12, more preferably 5 to 11, even more preferably 6 to 10, even more preferably 6.5 to 9, and most preferably 7 to 8. pH values ​​within this range are particularly effective for removing small polar neutral molecules, as well as inorganic and organic salts. It is especially advantageous that the additional washing aqueous solution is alkaline or substantially neutral, particularly substantially neutral.

[0052] For the purposes of this invention, a continuous method is preferred for purifying the synthetic crude oil stream. Compared to a batch process, this method offers the advantages of achieving higher productivity and shorter downtime.

[0053] As described herein, washing a crude oil stream with a suitable washing solution may include mixing the crude oil stream with the washing solution and then separating the purified crude oil stream from the washing solution. Preferably, the washing step according to the method of the invention is carried out in a mechanical mixer, a static mixer, and / or a mixing clarifier. As described above for the treatment of carbonyl streams, the washing step being carried out in a mixing clarifier has proven particularly advantageous.

[0054] In accordance with the present invention, it has been found that synthetic crude oil has an increased tendency to form gums, especially when it contains high levels of diene compounds in addition to the aforementioned aromatic compounds. Therefore, reactive dienes can also act as gum-forming agents and lead to harmful deposits in refining systems. For example, dienes can sometimes undergo Diels-Alder reactions, resulting in intermolecular crosslinking and ultimately deposit formation. Furthermore, dienes can form stable complexes with catalysts in hydrotreating units. Therefore, within the scope of the present invention, it has been found advantageous to reduce the diene content in synthetic crude oil, in addition to reducing the content of the aforementioned aromatic compounds.

[0055] It has been demonstrated that carbonyl compounds contained in a carbonyl stream can also react with diene compounds. Carbonyl compounds can undergo an oxo-Diels–Alder reaction with diene compounds, thereby converting the diene compounds into diene-free products. However, the oxo-Diels–Alder reaction is energy-disadvantaged and therefore occurs only to a limited extent.

[0056] In the present invention, it has been surprisingly found that the removal of diene compounds is significantly facilitated if the contact between the synthetic crude oil stream and the carbonyl stream is carried out in the presence of nitrogen compounds, and / or if a composition containing nitrogen compounds is added to the mixture of the synthetic crude oil stream and the carbonyl stream.

[0057] In their experiments, the inventors surprisingly discovered that adding nitrogen compounds (such as amines) resulted in a distinctive orange-red coloration. Careful examination revealed the formation of tetrahydropyridine compounds, which the inventors believe are responsible for this coloration. Simultaneously, a sharp decrease in diene value was observed, indicating the removal of diene compounds. This, among other things, is also demonstrated in Example 2.

[0058] According to the inventors, the reason why diene compounds are removed more efficiently in the presence of amines is that amines can react with carbonyl compounds to form imines. These imines are much more nucleophilic than the initial carbonyl compounds, and therefore they more readily undergo hetero-Diels-Alder reactions with dienes. The more readily occurring reaction is the aza-Diels-Alder reaction, rather than the oxa-Diels-Alder reaction. The following diagram illustrates this process as an example:

[0059]

[0060] In this scheme, a primary amine is used as an example. The reaction can also proceed in the same manner with NH3 or other compounds. In principle, various reactions occurring in the mixture may also produce open systems, but these open systems can also be separated and thus removed in the same way.

[0061] In a preferred embodiment, the method for purifying synthetic crude oil stream according to the present invention includes the following steps:

[0062] – Provide a synthetic crude oil stream, wherein the synthetic crude oil stream contains aromatic compounds and diene compounds, and preferably has a diene value of at least 0.1 g / 100 g;

[0063] – A synthetic crude oil stream is contacted with a carbonyl stream containing at least one carbonyl compound selected from aldehydes and ketones to form a mixture, whereby at least a portion of the aromatic compound is crosslinked into a condensation product; wherein the contact between the synthetic crude oil stream and the carbonyl stream is carried out in the presence of a nitrogen compound, and / or a composition containing a nitrogen compound is added to the mixture of the synthetic crude oil stream and the carbonyl stream, thereby converting at least a portion of the diene compound into a diene-free product; and

[0064] – The condensation products and diene-free products are separated from the mixture to obtain a purified synthetic crude oil stream.

[0065] The diene compounds contained in the synthetic crude oil stream are preferably compounds containing conjugated or cumulative carbon-carbon double bonds, especially conjugated carbon-carbon double bonds. Such compounds tend to form gums, for example, via the Diels-Adel reaction, and can be removed particularly effectively by the method according to the invention.

[0066] Those skilled in the art are familiar with methods for determining diene values. Preferably, the diene value is determined according to ASTM UOP326-07 standard.

[0067] The diene value of the synthetic crude oil stream is preferably at least 0.1 g / 100 g, more preferably at least 0.2 g / 100 g, more preferably at least 0.3 g / 100 g, more preferably at least 0.4 g / 100 g, more preferably at least 0.5 g / 100 g, more preferably at least 0.6 g / 100 g, more preferably at least 0.7 g / 100 g, more preferably at least 0.8 g / 100 g, more preferably at least 0.9 g / 100 g, more preferably at least 1.0 g / 100 g, more preferably at least 1.1 g / 100 g, more preferably at least 1.2 g / 100 g, more preferably at least 1.3 g / 100 g, more preferably at least 1.4 g / 100 g, more preferably at least 1.5 g / 100 g, more preferably at least 1.6 g / 100 g, more preferably at least 1.7 g / 100 g, more preferably at least 1.8 g / 100 g, more preferably at least 1.9 g / 100 g, and more preferably at least 2.0 g / 100 g. g / 100g. The diene value of the synthetic crude oil stream is preferably in the range of 0.1 g / 100 g to 15 g / 100 g, more preferably 1.0 g / 100 g to 12 g / 100 g, and particularly 1.5 g / 100 g to 10 g / 100 g.

[0068] The purified synthetic crude oil stream preferably has a lower diene value than the synthetic crude oil stream. The diene value of the purified synthetic crude oil stream is preferably less than 5 g / 100 g, more preferably less than 4 g / 100 g, more preferably less than 3 g / 100 g, more preferably less than 2 g / 100 g, more preferably less than 1.5 g / 100 g, more preferably less than 1 g / 100 g, more preferably less than 0.9 g / 100 g, more preferably less than 0.8 g / 100 g, more preferably less than 0.7 g / 100 g, more preferably less than 0.6 g / 100 g, and more preferably less than 0.5 g / 100 g. The range of the diene value of the purified synthetic crude oil stream is preferably from 0.01 g / 100 g to 5 g / 100 g, more preferably from 0.1 g / 100 g to 2 g / 100 g, and particularly from 0.2 g / 100 g to 1 g / 100 g.

[0069] Preferably, the at least one nitrogen compound is selected from ammonia, primary amines, and / or secondary amines. These nitrogen compounds have proven highly suitable for the removal of diene compounds. It has been shown that the reaction proceeds more readily when using smaller nitrogen compounds. Primary amines and ammonia, especially ammonia, have proven particularly advantageous.

[0070] Preferably, the at least one nitrogen compound is selected from ammonia, methylamine, dimethylamine, ethylamine, diethylamine, ethanolamine, diethanolamine, 3-methoxypropylamine, dibutylamine, morpholine and / or triethylamine.

[0071] It has been demonstrated that using high concentrations of nitrogen compounds can further promote the removal of diene compounds. Therefore, it is preferred that the concentration of nitrogen compounds be at least 0.01% (w / w), more preferably at least 0.02% (w / w), more preferably at least 0.05% (w / w), more preferably at least 0.1% (w / w), and more preferably at least 0.2% (w / w) based on the total mass of the synthetic crude oil stream and the carbonyl stream. The concentration of nitrogen compounds is preferably from 0.01% (w / w) to 5% (w / w), more preferably from 0.02% (w / w) to 2% (w / w), and more preferably from 0.05% (w / w) to 0.5% (w / w) based on the total mass of the synthetic crude oil stream and the carbonyl stream.

[0072] It has been shown that it is advantageous if the concentrations of the carbonyl compound and the nitrogen compound are similar. According to the inventors, this is because one carbonyl compound molecule can react with one nitrogen compound molecule to form an imine. In a preferred embodiment, the molar ratio of the carbonyl compound to the nitrogen compound in the mixture of the synthetic crude oil stream and the carbonyl stream is therefore between 1:5 and 5:1, preferably between 1:2 and 2:1.

[0073] The separation of the diene-free product can be carried out in the same manner as described above for the condensation product; in particular, the diene-free product and the condensation product can be separated together. The condensation product and the diene-free product are preferably separated together, particularly in a mixing clarifier, by a polar phase (preferably an aqueous phase). Preferably, the diene-free product exists in the polar phase in at least partially dissolved and / or at least partially particulate form.

[0074] In a preferred embodiment of the method according to the invention, a purified synthetic crude oil stream, a second purified synthetic crude oil stream, or a third purified synthetic crude oil stream is fed into a hydrotreating unit. It has been found that reducing the diene content in the synthetic crude oil stream is particularly advantageous, especially during the hydrotreating process in the hydrotreating unit, because dienes can form stable complexes with the catalyst in such systems. Therefore, combining the method according to the invention with hydrotreating can significantly improve the lifespan of the hydrotreating unit, especially the lifespan of the catalyst used.

[0075] For the purposes of this invention, "synthetic crude oil stream" is preferably understood to refer to a stream of material containing synthetic crude oil or synthetic crude oil fractions. Preferably, the synthetic crude oil stream consists of synthetic crude oil or its fractions. Within the scope of this invention, it is particularly preferred that the synthetic crude oil stream contains pyrolysis oil or its fractions, especially consisting of pyrolysis oil or its fractions. The pyrolysis oil is preferably pyrolysis oil obtained from biomass (especially wood) and / or plastics. If the synthetic crude oil stream is a mixture of hydrocarbons obtained from the depolymerization of biomass or plastic materials (especially plastic materials), the method according to the invention has proven particularly applicable. Therefore, the synthetic crude oil stream is preferably a plastic pyrolysis product or its fraction, or a biomass pyrolysis product (especially wood pyrolysis product) or its fraction. However, the method according to the invention is also very applicable to other synthetic crude oils and their fractions. In a further preferred embodiment, the synthetic crude oil stream therefore contains shale oil or modified bitumen, preferably consisting of shale oil or modified bitumen.

[0076] In a particularly preferred embodiment, the synthetic crude oil stream is thus generated by the depolymerization of plastic materials (particularly plastic waste). Those skilled in the art are familiar with producing synthetic crude oil streams by depolymerizing plastic materials. Such methods are known, for example, see WO 2012 / 149590 A1 and US 6,060,631 A.

[0077] In a preferred embodiment, the plastic material includes polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyamide (PA), styrene-acrylonitrile (SAN), and / or acrylonitrile-butadiene-styrene (ABS). The method according to the invention has proven particularly suitable for purifying pyrolysis oils obtained from the aforementioned plastic materials.

[0078] Surprisingly, it has been found that the effects of the present invention can also be achieved, at least to some extent, through plastic materials containing a carbonyl source, which releases at least one carbonyl compound selected from aldehydes and ketones during pyrolysis. Particularly preferred is that the carbonyl source is an aldehyde source, wherein during pyrolysis, aldehydes are released from the aldehyde source, and these aldehydes crosslink with at least a portion of aromatic compounds to form condensation products. In this case, similar effects to those achieved when carbonyl compounds are supplied externally via a carbonyl stream can be achieved. Unlike externally added carbonyl compounds, these are formed internally during the process, thus simplifying the method. Preferably, the carbonyl source (or aldehyde source) decomposes at least partially during pyrolysis to form at least one carbonyl compound (or aldehyde).

[0079] Even if the plastic material contains a carbonyl source, it may still be advantageous to add an additional carbonyl stream containing at least one carbonyl compound in order to further increase the amount of carbonyl compound available for the desired crosslinking reaction.

[0080] Surprisingly, cellulose and / or starch have been found to be particularly suitable carbonyl sources. It has been demonstrated that these materials decompose at high temperatures during pyrolysis to form aldehydes, which can then undergo the desired reactions. Therefore, cellulose and / or starch can also be referred to as aldehyde sources. This has proven particularly advantageous because cellulose and starch are present in various wastes, such as waste paper or biomass. Advantageously, using the method according to the invention, a certain proportion of waste paper and / or biomass can be co-treated with plastic waste, thereby producing a synergistic effect on the removal of unwanted aromatic compounds and / or diene compounds from the pyrolysis oil. Mixed wastes containing a certain amount of paper and / or biomass in addition to plastics can also be used.

[0081] The carbonyl source preferably includes cellulose and / or starch, and is more preferably composed of cellulose and / or starch. The cellulose and / or starch can be modified cellulose and / or starch, particularly HES, cellulose acetate, HMC, and / or HMS. However, it can also be unmodified cellulose and / or starch.

[0082] In a preferred embodiment, the carbonyl source comprises paper, and is preferably composed of paper.

[0083] The concentration of the carbonyl source in the plastic material is preferably at least 0.1% (w / w), more preferably at least 0.2% (w / w), more preferably at least 0.5% (w / w), more preferably at least 1% (w / w), more preferably at least 2% (w / w), and more preferably at least 5% (w / w). It has been shown that higher concentrations result in greater aldehyde generation, thereby enabling better removal of aromatic compounds and / or diene compounds. The concentration is preferably between 0.1% (w / w) and 15% (w / w), more preferably between 0.2% (w / w) and 12% (w / w), more preferably between 0.5% (w / w) and 10% (w / w), and even more preferably between 1% (w / w) and 5% (w / w).

[0084] In a preferred embodiment, the plastic material comprises a nitrogen-containing polymer, wherein during the pyrolysis of the plastic material, the nitrogen-containing polymer decomposes at least partially and forms at least one nitrogen compound selected from ammonia, primary amines and / or secondary amines.

[0085] As has been demonstrated, with respect to the method according to the invention, the preferred presence of nitrogen compounds when the synthetic crude oil stream comes into contact with the carbonyl stream can also be achieved, at least in part, through a plastic material having a nitrogen source in the form of a nitrogen-containing polymer. Therefore, the aforementioned advantages, particularly improved removal of diene compounds, can be achieved. These advantages are also evident if the carbonyl compounds are not provided in the form of the carbonyl stream, but rather formed from the carbonyl source during the aforementioned pyrolysis process.

[0086] Preferably, the nitrogen-containing polymer comprises polyamide, and is preferably composed of polyamide. Particularly preferred are aliphatic polyamides, especially PA6, PA6.6, PA6.4 and / or PA11.

[0087] In a preferred embodiment, the nitrogen-containing polymer includes nitrogen-containing biopolymers, and is preferably composed of nitrogen-containing biopolymers.

[0088] The concentration of the nitrogen-containing polymer in the plastic material is preferably at least 0.1% (w / w), more preferably at least 0.2% (w / w), more preferably at least 0.5% (w / w), more preferably at least 1% (w / w), more preferably at least 2% (w / w), and more preferably at least 5% (w / w). It has been shown that higher concentrations can lead to the formation of a larger amount of the at least one nitrogen compound, thereby enabling better removal of the diene compound. The concentration is preferably between 0.1% (w / w) and 30% (w / w), more preferably between 0.2% (w / w) and 20% (w / w), more preferably between 0.5% (w / w) and 12% (w / w), and more preferably between 1% (w / w) and 5% (w / w).

[0089] Unless otherwise stated, all parameters mentioned herein refer to SATP conditions as specified by IUPAC (“Standard Ambient Temperature and Pressure”), specifically a temperature of 25°C and a pressure of 101,300 Pa.

[0090] Unless otherwise stated, all percentages (%) in this document refer to weight percentages.

[0091] Unless otherwise stated, all mixing ratios specified herein refer to volume mixing ratios, i.e., volume ratios (volume:volume). Attached Figure Description

[0092] The present invention will be described with reference to the following figures and embodiments, but the present invention is not limited thereto.

[0093] Figure 1 A flowchart of a preferred embodiment of the method according to the present invention is shown. Detailed Implementation

[0094] exist Figure 1In the illustrated embodiment, synthetic crude oil stream 1 is obtained by depolymerization of a plastic material. The plastic material is compacted, degassed, and melted in an extruder 12. The plastic melt discharged from the extruder 12 is mixed in a static mixer 13 with an external solvent 14 (preferably heavy oil) and / or with pyrolyzed plastic material recovered as a recovery stream 15 to reduce the viscosity of the plastic melt. The resulting mixture is introduced into a depolymerization reactor 16, where the plastic material is preferably depolymerized at a temperature between 400°C and 440°C. The pyrolyzed plastic material is obtained as the top product of column 17. In the illustrated embodiment, the top product is then contacted with a composition 4 containing a nitrogen compound (preferably NH3). In another column 19, a gas stream 18 is separated from the resulting mixture to obtain synthetic crude oil stream 1. The synthetic crude oil stream contains aromatic compounds and diene compounds, and preferably has a diene value of at least 0.1 g / 100 g.

[0095] In the illustrated embodiment, synthetic crude oil stream 1 and carbonyl stream 2 are mixed in the mixing zone of the first mixing clarifier 8, preferably at a volume ratio of 1:1. Carbonyl stream 2 is preferably an alkaline aqueous solution containing formaldehyde. The temperature of the mixture of synthetic crude oil stream 1 and carbonyl stream 2 is preferably at least 50°C. The aromatic compounds contained in synthetic crude oil stream 1 undergo at least a partial condensation reaction with formaldehyde and precipitate as insoluble condensation products. Furthermore, formaldehyde reacts with NH3 from composition 4 to form an imine compound, which undergoes an Aza-Diels-Alder reaction with a diene compound, converting it into a diene-free product. Therefore, in the settling zone of the mixing clarifier 8, the oil phase separates from the aqueous phase. The condensation products and the diene-free product are separated from the aqueous phase. The average residence time in the first mixing clarifier 8 is preferably between 5 minutes and 30 minutes. The aqueous phase is removed as part of the wastewater stream 11, and the oil phase is separated as purified synthetic crude oil stream 3.

[0096] Example 1: Using carbonyl compounds to reduce the aromatic content in pyrolysis oil

[0097] To investigate the use of carbonyl compounds to remove unwanted aromatic compounds, laboratory tests were conducted using pyrolysis oils. In the experiments, different pyrolysis oils were mixed with carbonyl compounds, nitrogen compounds, acids, and / or bases, and heated to 50°C to 160°C for 1 to 30 minutes.

[0098] The aqueous phase was then removed, and the reaction solution was analyzed directly by gas chromatography (GC) according to ASTM D 6591-19 and ASTM D5134-21.

[0099] Experiment 1:

[0100] Light products (boiling range IBP-175℃) obtained from the pyrolysis of waste plastics were used as pyrolysis oil. The carbonyl compounds used, reaction conditions, and the measured proportions of aromatics in the products are shown in the table below (percentages refer to weight percentages):

[0101] Therefore, treatment with formaldehyde (an aldehyde) and acetone (a ketone) both significantly reduce the aromatic content in pyrolysis oil. This effect is observed regardless of the presence of other reagents. Treatment with aldehydes shows a greater reduction compared to treatment with ketones.

[0102] Experiment 2:

[0103] Heavy products (boiling range IBP 175-410℃) obtained from the pyrolysis of waste plastics were used as pyrolysis oil. In addition to the total aromatic hydrocarbon content, the proportion of tetracore aromatics was also determined in this experiment. This determination was performed according to ASTM D 6591-19 and ASTM D5134-21. The carbonyl compounds used, reaction conditions, and the measured proportions of aromatics in the products are shown in the table below (percentages refer to weight percentages):

[0104] Therefore, treatment with carbonyl compounds also resulted in a significant reduction in the content of tetracyclic aromatic hydrocarbons, and the presence of bases further promoted this removal compared to the presence of acids.

[0105] Experiment 3:

[0106] Light gas oil produced from the pyrolysis of waste plastics was used as the pyrolysis oil. The carbonyl compounds used, reaction conditions, and the measured proportions of aromatics in the products are shown in the table below (percentages are by weight):

[0107] Example 2: Using carbonyl compounds and nitrogen compounds to reduce the diene value of pyrolysis oil

[0108] Laboratory tests were conducted to investigate the reduction in diene value of the pyrolysis oil. Light products (boiling range IBP – 175°C) obtained from the pyrolysis of waste plastics were used as the pyrolysis oil. For the tests, all components were heated together in a sealed container. The aqueous phase was then removed, and the reaction solution was directly analyzed by GC (according to ASTM D 6591-19 and ASTM D5134-21).

[0109] The carbonyl compounds used, reaction conditions, and diene values ​​obtained are shown in the table below (percentages refer to weight percentages):

[0110] The results clearly show that carbonyl compounds alone can reduce the diene value, with aldehydes (formaldehyde) being more effective than ketones (acetone). Adding nitrogen compounds can significantly increase the reduction in diene value, thus ammonia (NH3) has proven to be more suitable than monoethanolamine.

[0111] Example 3: Reducing the diene value of pyrolysis oil by using carbonyl sources in the feedstock

[0112] To study the effect of carbonyl sources in the feedstock on the reduction of diene value in pyrolysis oil, basically following the... Figure 1 The diagram shows a pilot run of synthetic crude oil production. The starting material used was a plastic mixture to which varying amounts of paper were added as a carbonyl source, or more specifically, as an aldehyde source.

[0113] The starting materials, with or without paper, were pyrolyzed at temperatures between 400°C and 480°C, and as... Figure 1 Separation was performed as shown. In some pilot runs, nitrogen compounds were also added to the obtained synthetic crude oil stream at a rate of 0.5–2 kg / h. The nitrogen compounds were added at a temperature of 300–400 °C. As described above, the condensation products and diene-free products were separated by polar phase separation.

[0114] Diene values ​​were measured for each trial run and compared with each other.

[0115]

[0116] These results show that adding paper to the raw material can significantly reduce the diene value. This effect is further enhanced in the presence of amines.

Claims

1. A method for purifying synthetic crude oil stream (1), the method comprising the following steps: – Provide the synthetic crude oil stream (1), wherein the synthetic crude oil stream (1) contains aromatic compounds; – The synthetic crude oil stream (1) is contacted with a carbonyl stream (2) containing at least one carbonyl compound selected from aldehydes and ketones to form a mixture, thereby crosslinking at least a portion of the aromatic compound into a condensation product; as well as – The condensation product is separated from the mixture to obtain a purified synthetic crude oil stream (3).

2. The method according to claim 1, wherein the aromatic content of the synthetic crude oil stream (1) is at least 10% (w / w).

3. The method according to any one of the preceding claims, wherein, The synthetic crude oil stream (1) is brought into contact with the carbonyl stream (2) at a temperature of at least 50°C.

4. The method according to any one of the preceding claims, wherein the carbonyl stream (2) is an aqueous solution.

5. The method according to any one of the preceding claims, wherein the contact between the synthetic crude oil stream (1) and the carbonyl stream (2) is carried out in the presence of an acid or a base, and / or wherein an acid or a base is added to the mixture of the synthetic crude oil stream (1) and the carbonyl stream (2).

6. The method according to any one of the preceding claims, wherein the at least one carbonyl compound is formaldehyde.

7. The method according to any one of the preceding claims, wherein, Based on the total mass of the synthetic crude oil stream (1) and the carbonyl stream (2), the concentration of the carbonyl compound is at least 0.01% (w / w).

8. The method according to any one of the preceding claims, wherein the mixture formed from the synthetic crude oil stream (1) and the carbonyl stream (2) has a polar phase and a non-polar phase, wherein the condensation product is mainly present in the polar phase, and wherein the condensation product is separated from the mixture by separating the polar phase.

9. The method according to any one of the preceding claims, wherein the contact between the synthetic crude oil stream (1) and the carbonyl stream (2) is carried out in the presence of a nitrogen compound, and / or wherein a composition (4) containing a nitrogen compound is added to the mixture of the synthetic crude oil stream (1) and the carbonyl stream (2).

10. The method according to any one of the preceding claims, wherein at least one nitrogen compound is selected from ammonia, primary amines and / or secondary amines; preferably selected from ammonia, methylamine, dimethylamine, ethylamine, diethylamine, ethanolamine, diethanolamine, 3-methoxypropylamine, dibutylamine, morpholine and / or triethylamine.

11. The method according to any one of the preceding claims, wherein, Based on the total mass of the synthetic crude oil stream (1) and the carbonyl stream (2), the concentration of the nitrogen compound is at least 0.01% (w / w).

12. The method according to any one of the preceding claims, wherein the synthetic crude oil stream (1) is generated by depolymerization of plastic materials, particularly plastic waste.

13. A method for producing a purified synthetic crude oil stream (3) from a plastic material, comprising the following steps: – Provide a plastic material, wherein the plastic material contains a carbonyl source; – The plastic material is pyrolyzed to obtain a synthetic crude oil stream (1) containing aromatic compounds, wherein at least one carbonyl compound selected from aldehydes and ketones is released from the carbonyl source, and wherein the at least one carbonyl compound is crosslinked with at least a portion of the aromatic compound to form a condensation product. as well as – Separate the condensation product to obtain a purified synthetic crude oil stream (3).

14. The method of claim 13, wherein the carbonyl source comprises cellulose and / or starch.

15. The method according to claim 13 or 14, wherein the plastic material comprises a nitrogen-containing polymer, preferably a polyamide, wherein during the pyrolysis of the plastic material, the nitrogen-containing polymer decomposes at least partially and forms at least one nitrogen compound selected from ammonia, primary amines and / or secondary amines.

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