Methods for refining synthetic crude oil flows

Abstract

To provide a method for purifying a flow of synthetic crude oil.SOLUTION: A method for purifying a flow of synthetic crude oil includes a step of supplying a flow of synthetic crude oil, a step of cleaning the flow of the synthetic crude oil with first water-soluble cleaning liquid at a first temperature, so as to obtain a flow of first purified synthetic crude oil, and a step of cleaning the flow of the first purified synthetic crude oil with second water-soluble cleaning liquid at a second temperature, so as to obtain a flow of second purified synthetic crude oil, wherein the first water-soluble cleaning liquid is basic, the second water-soluble cleaning liquid is acid, and the second temperature is lower than the first temperature. A method for producing synthetic crude oil includes a step of producing a flow (1) of synthetic crude oil by depolymerization of, preferably, a synthetic resin material, particularly, a synthetic resin waste, and a step of purifying the flow (1) of the synthetic crude oil according to the method of the present invention.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for purifying the flow of synthetic crude oil.

Background Art

[0002] Synthetic crude oil, which may also be referred to as syncrude, can be obtained from various methods. For example, synthetic crude oil can be shale oil obtained from oil shale by pyrolysis. Another source is hydrocarbons obtained from oil sands, particularly bitumen, from which synthetic crude oil can be obtained by upgrading. Furthermore, synthetic crude oil can also be produced by decomposition from synthetic resin materials, such as synthetic resin waste.

[0003] Synthetic crude oil usually contains various impurities, which have an adverse effect on the purification method and purification plant, and in certain purification methods, the crude oil can become completely unsuitable. The types and contents of impurities can vary greatly depending on the source and method of obtaining the synthetic crude oil.

[0004] WO 2020 / 020769 A1 describes a method for purifying recyclable or renewable organic materials, including heating a material in the presence of a water-soluble alkali metal hydroxide solution and subjecting it to hydrotreating in the presence of a hydrotreating catalyst to obtain a purified material with a reduced chlorine content.

[0005] WO 2021 / 105326 A1 describes a method for treating liquefied synthetic resin waste. This method includes pretreatment of the liquefied synthetic resin waste with an aqueous medium having a pH value of at least 7 at a temperature of at least 200°C to obtain a feed for a steam cracker, followed by hydrotreating and post-treatment.

[0006] WO 2014 / 165859 A1 describes a method and apparatus for treating synthetic crude oil, where the synthetic crude oil is washed with a basic process water-soluble cleaning liquid to reduce the acidity level. This method may also include two or more washing steps.

[0007] Further methods for refining or processing oil are described in US 9 045 698 B2, US 2006 / 144761 A1 and GB 590 635 A.

[0008] However, conventionally known refining methods are often complex and / or unsuitable. In particular, impurities, such as neutral compounds (esters, aldehydes, ketones, organohalogen compounds, amides, nitriles, etc.) and polycyclic amines, are often not removed adequately or at all. This is especially problematic in the case of complex starting materials, such as synthetic crude oil obtained from synthetic resin waste, where the impurity profile can vary significantly. Improperly removed impurities can then lead to problems in the further processing of the refined crude oil. Another problem is the formation of deposits in the plant, which is observed during many refining processes, making plant cleaning more difficult and hindering efficient operation. [Overview of the Initiative]

[0009] Therefore, there is still a need for new or improved methods for refining synthetic crude oil. The object of the present invention is to provide such a method. In particular, the object of the present invention is to provide a method for refining synthetic crude oil that enables the efficient and thorough removal of impurities, especially neutral compounds, as well as impurities in the form of acidic or basic compounds. Another object of the present invention is to minimize the formation of deposits during the refining process. Another object is to provide a refining method that is as efficient and economical as possible.

[0010] According to the present invention, this objective is achieved by a method for refining a stream of synthetic crude oil, comprising the following steps: Supply of synthetic crude oil; To obtain a first stream of refined synthetic crude oil, the stream of synthetic crude oil is washed with a first water-soluble washing solution at a first temperature; and to obtain a second stream of refined synthetic crude oil, the first water-soluble washing solution is basic, the second water-soluble washing solution is acidic, and the second temperature is lower than the first temperature.

[0011] In a further embodiment, the present invention relates to a method for producing synthetic crude oil, comprising the following steps. Preferably, the generation of a synthetic crude oil flow by depolymerization of synthetic resin materials, particularly synthetic resin waste; and the purification of a synthetic crude oil flow by a method for purifying a synthetic crude oil flow according to the present invention.

[0012] In the process of this invention, it was surprisingly advantageous to perform the basic cleaning step at a higher temperature, followed by the acidic cleaning step at a lower temperature. This surprising advantage arises from both the fact that the basic cleaning step is performed before the acidic cleaning step, and the fact that the temperature of the basic cleaning step is higher than that of the acidic cleaning step.

[0013] Regarding the order of the washing steps, surprisingly, it was found that performing the basic washing step before the acidic washing step could result in better phase separation as well as a significant reduction in sediment. When the acidic washing step was performed without prior basic washing, the inventors observed the formation of sediment, which turned out to be mainly deposited wax carboxylic acids. Wax carboxylic acids are, for example, long-chain carboxylic acids with a chain length of 20 to 75 carbon atoms. In addition to paraffinic unbranched and branched chains, wax carboxylic acids may also have aromatic, olefinic, and heteroatomic functionalities. Wax carboxylic acids are present in many synthetic crude oils, particularly in pyrolysis oils (e.g., from the pyrolysis of synthetic resins). This is because these compounds can be increasingly formed during pyrolysis treatment, for example, from the reaction with introduced oxygen, or by already existing functional polymers or additives. In synthetic crude oils, wax carboxylic acids often exist in a bound state as salts. In the process of the present invention, it was found that when a stream of unreprocessed synthetic crude oil is treated with an acidic, water-soluble washing solution, the bound wax carboxylic acids can be protonated and thus released. The wax carboxylic acids released in this manner can, on the one hand, deposit and form unwanted sediments, and on the other hand, they can act as surfactants, forming mixed phases or binding to unwanted compounds such as water, heavy metals, and nitrogen compounds in the oil phase. Furthermore, wax carboxylic acids that are not removed can cause corrosion in the plant and act as catalytic poisons in subsequent processing of synthetic crude oil.

[0014] In the process of the present invention, it has been found that the release of bound wax carboxylic acids and related problems can be reduced by performing a basic washing step before the acidic washing step. When washing with a basic water-soluble washing solution, the wax carboxylic acids exist mainly in a deprotonated state and can be removed via the aqueous phase, thus reducing their adverse effects in the subsequent acidic washing step. The sequence of washing with a first water-soluble washing solution and a second water-soluble washing solution provided by the present invention can therefore result in a reduction of deposits in the plant, better phase separation, and thus better removal of impurities, a reduction in corrosion in the plant, and protection of the catalyst during further processing.

[0015] Furthermore, it has been shown that performing the basic cleaning process at high temperatures is advantageous for the removal of wax carboxylic acids. Higher temperatures result in better solubility of wax carboxylic acids in the aqueous phase. Therefore, it is advantageous if the cleaning of the synthetic crude oil flow with the first water-soluble cleaning solution is carried out at temperatures above 70°C. It has been found that temperatures above 95°C are particularly advantageous, as many salts of wax carboxylic acids, especially alkali salts, dissolve particularly well in water at these temperatures and can be removed particularly efficiently through the aqueous phase.

[0016] Conventionally, basic water-soluble washing solutions have been mainly used to reduce acid levels in synthetic crude oil. In the process of the present invention, it has been found that even neutral compounds such as esters, aldehydes, ketones, organic halogen compounds, amides, and nitriles can be removed using a basic water-soluble washing solution. In the method according to the present invention, such neutral compounds can be hydrolyzed by a first water-soluble washing solution. The basic hydrolysis products include acidic compounds removed in the basic washing process, such as carboxylic acids, and basic compounds that can be removed in a subsequent acidic washing step, such as amines.

[0017] This offers further advantages when the basic washing step is carried out at higher temperatures. Acidic compounds such as carboxylic acids and phenols only need to be deprotonated during basic washing to be removed with the water-soluble washing solution, but neutral compounds that cannot be deprotonated under washing conditions must undergo hydrolysis. Hydrolysis is temperature-dependent and proceeds faster at higher temperatures. Therefore, higher temperatures in the basic washing step result in better removal of neutral compounds. In this context, it is preferable if the washing of the synthetic crude oil flow with the first water-soluble washing solution is carried out at temperatures above 70°C. Even higher temperatures, such as above 95°C, and especially above 100°C, have been proven to be particularly suitable for the removal of neutral compounds.

[0018] In addition to removing hydrolysis products from the basic washing process, washing the first purified synthetic crude oil stream with an acidic, water-soluble washing solution provided in the method according to the present invention allows for the removal of further basic compounds such as amines, pyridines, and other basic impurities. As a result, polycyclic amines, in particular, can also be efficiently removed. Polycyclic amines can be more abundant in synthetic crude oil, especially in pyrolysis oil. They can be formed by crack treatment, for example, in the presence of a nitrogen source, such as additives, or polymers such as polyamide (PA), polyacrylonitrile (PAN), or acrylonitrile-butadiene-styrene copolymer (ABS). In the case of polycyclic amines, they may be, for example, polycondensation-saturated, mono- and polyunsaturated, or aromatic ring systems. They can be partially dissolved in the synthetic crude oil or suspended in the colloidal region, often resulting in undesirable deposits, thus leading to more difficult cleaning of the plant. Furthermore, they can lead to blocking of the active surface of catalysts in subsequent applications. Furthermore, these methods can dissolve undesirable compounds such as salts, chlorides, heavy metals, or sulfides in the organic product phase. It has been found that polycyclic amines can be efficiently removed by the methods according to the present invention. For the removal of polycyclic amines, it has been proven advantageous that the acidic washing step is carried out at a temperature of at least 20°C. This removal is particularly efficient when the temperature is at least 50°C.

[0019] However, in the course of the invention, it was found that it is surprisingly advantageous when the temperature in the acidic cleaning step is not too high, especially when it is lower than the temperature in the basic cleaning step. Thus, it was found that high temperatures in the acidic cleaning step can lead to a decrease in product recovery and the formation of impurities. In the inventor's view, although not bound by theory, this can be explained by the reaction of the olefin with the acid used, for example, by hydroxysulfonation or sulfurization with sulfuric acid, or by reaction with other acids. Alcohols, sulfonates, sulfates, and hydroxysulfonates can be formed as impurities, which can lead to deposits and thus more difficult cleaning and corrosion. Therefore, it was found that it is advantageous to carry out the acidic cleaning step at a temperature of 120°C or lower. In particular, these adverse effects can be minimized when the temperature is 100°C or lower, and more preferably 95°C or lower.

[0020] A further advantage of lower temperatures in the acidic cleaning step is the significantly lower demands on the materials used in the cleaning equipment. The presence of acidic solutions at high temperatures often necessitates the use of special materials or coatings, which would lead to a significant increase in cost.

[0021] A further advantage of the series of washing steps in the method according to the present invention is that the method can be carried out particularly economically, especially in relation to preferred embodiments in which the basic and acidic washing steps are part of a continuous method. Synthetic crude oil is usually obtained from high-temperature processing, such as pyrolysis or decomposition. If the production method according to the present invention is downstream of such processing, heating of the synthetic crude oil stream is not required if the basic washing step is carried out before the acidic washing step. The synthetic crude oil stream obtained from the production method can be washed with a first water-soluble washing solution directly or after cooling to a first temperature, and the first refined synthetic crude oil stream obtained therefrom can be washed with a second water-soluble washing solution after being further cooled to a second temperature. The fact that the synthetic crude oil stream does not need to be heated between washing steps makes the method particularly economical and efficient. Therefore, in relation to the method according to the present invention, it is particularly preferable that the synthetic crude oil stream is not heated between washing at the first temperature and washing at the second temperature.

[0022] In a preferred embodiment of the method according to the present invention, the first temperature is 70°C or higher, preferably 80°C or higher, more preferably 90°C or higher, more preferably 95°C or higher, even more preferably 100°C or higher, even more preferably 105°C or higher, even more preferably 110°C or higher, even more preferably 115°C or higher, even more preferably 120°C or higher, even more preferably 125°C or higher, even more preferably 130°C or higher, and most preferably 135°C or higher. Providing such a high first temperature has the advantage that wax carboxylic acids present in the synthetic crude oil flow can be better dissolved and removed by basic washing. A further advantage of the high first temperature is that the basic hydrolysis reaction proceeds particularly rapidly, and therefore neutral compounds can be removed particularly well. It is particularly preferable when the first temperature is in the range of 70°C to 190°C, preferably 80°C to 180°C, more preferably 90°C to 170°C, even more preferably 95°C to 165°C, even more preferably 100°C to 160°C, even more preferably 105°C to 155°C, even more preferably 110°C to 150°C, and most preferably 115°C to 145°C.

[0023] In a preferred embodiment of the method according to the present invention, the second temperature is 120°C or lower, preferably 110°C or lower, more preferably 100°C or lower, even more preferably 95°C or lower, even more preferably 90°C or lower, even more preferably 80°C or lower, and most preferably 75°C or lower. Providing such lower temperatures has the advantage that impurity formation can be reduced and product yield can be increased. An additional advantage of lower temperatures is that the washing equipment is subjected to harsher conditions and therefore requires less expensive materials or material coatings. At the same time, basic compounds such as amines and pyridines are protonated only, but in contrast to neutral compounds, they do not require hydrolysis reactions to remove these compounds and can still be removed efficiently. It is particularly preferred when the second temperature is in the range of 20°C to 120°C, preferably 30°C to 110°C, more preferably 40°C to 100°C, even more preferably 50°C to 90°C, even more preferably 60°C to 80°C, and even more preferably 65°C to 75°C. This has the advantage, on the one hand, that the temperature is low enough to minimize the formation of impurities, and on the other hand, that the temperature is high enough to efficiently remove polycyclic amines in particular.

[0024] In a preferred embodiment, the washing of the synthetic crude oil flow with the first water-soluble washing solution is carried out for an average washing time of 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. Providing a longer washing time for basic washing allows for more complete progress of the hydrolysis reaction, and as a result, neutral compounds can be removed more effectively. In particular, it is preferable when the average washing duration is 0.5 to 180 minutes, preferably 1 to 120 minutes, more preferably 2 to 60 minutes, even more preferably 5 to 30 minutes, and most preferably 12 to 20 minutes.

[0025] The average washing duration is preferably the average time while the synthetic crude oil stream is brought into contact with the first water-soluble washing liquid and the stream of the first purified synthetic crude oil is separated from the first water-soluble washing liquid. When the washing is carried out as a continuous process, the average washing duration preferably corresponds, for example, to the average residence time of the washing device in a mixer-settler.

[0026] In a preferred embodiment, the washing of the synthetic crude oil stream with the first water-soluble washing liquid is carried out at a higher pressure than the washing of the stream of the first purified synthetic crude oil with the second water-soluble washing liquid. Providing a higher pressure during the basic washing allows for a higher temperature and thus better removal of less soluble wax carboxylic acids as well as neutral compounds. In contrast, in acid washing, a lower pressure is advantageous because it can reduce the formation of unwanted impurities and also has lower material requirements, resulting in significant cost savings.

[0027] In a preferred embodiment, at least the washing of the synthetic crude oil stream with the first water-soluble washing liquid is carried out in a pressure vessel. By providing a pressure vessel, washing at higher pressures and temperatures becomes possible, thus enabling better removal of not only neutral compounds but also less soluble wax carboxylic acids.

[0028] Preferably, the washing of the synthetic crude oil stream with the first water-soluble washing liquid is carried out at a pressure of 2 bar or more, preferably 3 bar or more, more preferably 5 bar or more, still more preferably 7 bar or more, and most preferably 10 bar or more. As mentioned, providing such a high pressure allows for a high temperature and good removal of not only neutral compounds but also less soluble wax carboxylic acids. It is particularly preferred when the washing of the synthetic crude oil stream with the first water-soluble washing liquid is carried out at a pressure in the range of 2 bar to 50 bar, preferably 3 bar to 35 bar, more preferably 5 bar to 25 bar, still more preferably 7 bar to 20 bar, and most preferably 10 bar to 18 bar.

[0029] Preferably, the washing of the first purified synthetic crude oil stream with the second water-soluble washing liquid is carried out at a pressure of 12 bar or less, preferably 7 bar or less, more preferably 6 bar or less, even more preferably 5 bar or less. As mentioned, providing such a lower pressure allows the use of less expensive materials. It is particularly preferred when the washing of the first purified synthetic crude oil stream with the second water-soluble washing liquid is carried out at a pressure in the range from 1 bar to 12 bar, preferably from 1.5 bar to 7 bar, more preferably from 2 bar to 6 bar, even more preferably from 3 bar to 5 bar.

[0030] Within the scope of the present invention, it has been proven particularly advantageous if the pH value of the first water-soluble washing liquid is 8 or higher, preferably 9 or higher, more preferably 10 or higher, even more preferably 11 or higher, still more preferably 12 or higher, and most preferably 13 or higher. Such a high pH value promotes the hydrolysis reaction, by which neutral compounds can be removed particularly well. It is particularly preferred when the pH value of the first water-soluble washing liquid is in the range from 8 to 14, preferably from 9 to 13, more preferably from 9.5 to 12, and most preferably from 10 to 11.

[0031] In a preferred embodiment, the first water-soluble washing liquid contains sodium hydroxide. It is particularly preferred if the concentration of sodium hydroxide is between 0.5 and 10 wt%, especially between 1 and 5 wt%.

[0032] Regarding the washing of the first purified synthetic crude oil stream with the second water-soluble washing liquid, it has been found particularly advantageous if the pH value of the second water-soluble washing liquid is 6 or lower, preferably 5 or lower, more preferably 4 or lower, even more preferably 3 or lower, still more preferably 2 or lower, and most preferably 1 or lower. Thereby, basic impurities such as amines and pyridines can be removed particularly efficiently. It is particularly preferred when the pH value of the second water-soluble washing liquid is in the range from 0 to 6, preferably from 1 to 5, more preferably from 2 to 4, and most preferably from 2.5 to 3.5.

[0033] In a preferred embodiment, the second water-soluble cleaning solution contains sulfuric acid. The concentration of sulfuric acid is preferably 0.5 to 10% by weight, and particularly preferably 1 to 5% by weight.

[0034] It has been proven that a volume mixing ratio of 5:1 to 1:5, preferably 2.5:1 to 1:2.5, and more preferably 1.5:1 to 1:1.5, between the synthetic crude oil flow and the first water-soluble washing solution is advantageous. Such mixing ratios allow for particularly efficient removal of wax carboxylic acids and hydrolysis of neutral compounds, as well as particularly efficient removal of further acidic impurities.

[0035] Advantageously, the volumetric mixing ratio between the first refined synthetic crude oil stream and the second water-soluble washing solution is from 10:1 to 1:5, preferably from 5:1 to 1:2.5, and more preferably from 2.5:1 to 1:1.5. Such mixing ratios allow for particularly efficient removal of basic impurities.

[0036] Furthermore, the method according to the present invention may undergo further washing steps. For example, the first purified synthetic crude oil stream may undergo further washing or purification steps before washing with the second water-soluble washing solution. However, if no further purification steps are performed between washing the synthetic crude oil stream with the first water-soluble washing solution and washing the first purified synthetic crude oil stream with the second water-soluble washing solution, it is particularly preferable to have no washing steps, no filtration steps, and / or no hydrogenation steps. This has the advantage, in particular, that basic products formed from neutral compounds by basic hydrolysis can be removed in the acidic washing step immediately following the basic washing step.

[0037] Preferably, the method according to the present invention does not involve any filtration steps. Avoiding filtration steps leads to a particularly simple and economical method. Filtration steps can be avoided, in particular, because washing the synthetic crude oil stream with a basic, water-soluble washing solution is carried out at higher temperatures. This allows for efficient removal of wax carboxylic acids in particular, which are often less soluble at lower temperatures and may require filtration if removal is insufficient.

[0038] The method according to the present invention may also include a hydrogenation step for the additional removal of impurities. However, it is preferable that the method according to the present invention does not include a hydrogenation step. Avoiding the hydrogenation step results in a particularly simple and economical purification process. The washing step provided by the present invention enables particularly good removal of impurities even without providing a hydrogenation step at all.

[0039] In a particularly preferred embodiment, the method according to the present invention further includes the step of washing a second stream of refined synthetic crude oil with a third water-soluble washing solution at a third temperature to obtain a third stream of refined synthetic crude oil. Providing such an additional washing step makes it possible to remove particularly thorough impurities that may still be present after the basic and acidic washing steps.

[0040] In this regard, it is particularly preferable that the pH value of the third water-soluble washing solution is in the range of 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 ​​in this range are particularly effective in removing small polar neutral molecules, as well as inorganic and organic salts. It is particularly advantageous that the third water-soluble washing solution is basic or substantially neutral, especially substantially neutral.

[0041] In a preferred embodiment, the third water-soluble cleaning solution contains a neutral amine. This has the advantage of providing better protection for the subsequent plant.

[0042] In a preferred embodiment, the third temperature is lower than the first temperature. This eliminates the need to heat the crude oil flow before washing it with the third water-soluble cleaning solution, allowing the method to be carried out efficiently and economically.

[0043] Preferably, the third temperature is 120°C or lower, preferably 110°C or lower, more preferably 100°C or lower, even more preferably 90°C or lower, even more preferably 80°C or lower, and most preferably 75°C or lower. It is particularly preferable when the third temperature is in the range of 20°C to 120°C, preferably 30°C to 110°C, more preferably 40°C to 100°C, even more preferably 50°C to 90°C, even more preferably 60°C to 80°C, and even more preferably 65°C to 75°C.

[0044] It has been proven advantageous to perform the cleaning of a synthetic crude oil flow with a first water-soluble cleaning solution at a higher pressure than the cleaning of a second refined synthetic crude oil flow with a third water-soluble cleaning solution. Providing higher pressure during the basic cleaning allows for higher temperatures and therefore enables more thorough removal of not only neutral compounds but also poorly soluble wax carboxylic acids. However, when cleaning with the third water-soluble cleaning solution, lower pressure is advantageous because it reduces the requirements for the materials used, which can result in significant cost savings.

[0045] In a preferred embodiment, the washing of the second refined synthetic crude oil flow with the third water-soluble washing solution is carried out at a pressure of 12 bar or less, preferably 10 bar or less, more preferably 8 bar or less, and even more preferably 7 bar or less. Pressures in the range of 1 bar to 12 bar, preferably 1.5 bar to 10 bar, more preferably 2 bar to 8 bar, and even more preferably 3 bar to 7 bar are particularly preferred.

[0046] It has been proven that a volume mixing ratio of 10:1 to 1:5, preferably 5:1 to 1:2.5, and more preferably 2.5:1 to 1:1.5, between the second refined synthetic crude oil stream and the third water-soluble washing solution is advantageous. Such a mixing ratio enables particularly efficient removal of residual impurities.

[0047] In relation to the present invention, it is preferable that the process of purifying the synthetic crude oil stream is a continuous process. Compared to batch processing, this has the advantage of achieving higher productivity and shorter downtime. Preferably, the steps of washing the synthetic crude oil stream with a first water-soluble cleaning solution, washing the first purified synthetic crude oil stream with a second water-soluble cleaning solution, and, if provided, washing the second purified synthetic crude oil stream with a third water-soluble cleaning solution are therefore part of the continuous process. It is also preferable that the method of producing synthetic crude oil according to the present invention is a continuous process, i.e., the production of the synthetic crude oil stream, preferably by depolymerization of a synthetic resin material, is also part of the continuous process. Providing a continuous process has the advantage of avoiding heating of the synthetic crude oil stream, in particular, because the synthetic crude oil stream obtained from the production method can be washed with the first water-soluble cleaning solution directly or after cooling to a first temperature, or the first purified synthetic crude oil stream can be washed with the second water-soluble cleaning solution after cooling from a first temperature to a second temperature.

[0048] Typically, washing a crude oil stream with a water-soluble cleaning solution involves mixing the crude oil stream with the water-soluble cleaning solution and then separating the refined crude oil stream from the water-soluble cleaning solution.

[0049] Preferably, the cleaning steps of the method according to the present invention are carried out in a mechanical mixer, a static mixer, and / or a mixer settler. It has been particularly advantageous if the cleaning steps of the process according to the present invention are carried out in a mixer settler. Typically, a mixer settler includes a continuously operated mixing zone and a continuously operated settling zone, thus enabling the flow of synthetic crude oil to be mixed with the respective water-soluble cleaning solution, and enabling a subsequent settling process to separate the phases and separate the refined flow of synthetic crude oil in a continuous process.

[0050] In relation to the present invention, “synthetic crude oil stream” preferably means a stream of a substance containing synthetic crude oil or fractions of synthetic crude oil. The synthetic crude oil stream preferably consists of synthetic crude oil or fractions thereof. Within the scope of the present invention, it is particularly preferred that the synthetic crude oil stream includes, and especially consists of, pyrolysis oil or fractions thereof. Preferably, the pyrolysis oil is pyrolysis oil obtained from biomass, particularly wood and / or synthetic resins. The method according to the present invention has proven particularly suitable when the synthetic crude oil stream is a hydrocarbon mixture obtained from biomass or synthetic resin materials, particularly from the depolymerization of synthetic resin materials. Therefore, the synthetic crude oil stream is preferably a synthetic resin pyrolysis product or fraction thereof, or a biomass pyrolysis product, particularly a wood pyrolysis product or fraction thereof. However, the method according to the present invention is also well suitable for other synthetic crude oils and fractions thereof. In a further preferred embodiment, the synthetic crude oil stream preferably consists of shale oil or modified bitumen.

[0051] Therefore, in relation to the method according to the present invention for producing synthetic crude oil, it is preferable that the stream of synthetic crude oil is produced by the depolymerization of synthetic resin material, preferably synthetic resin waste. Those skilled in the art are familiar with the production of streams of synthetic crude oil by the depolymerization of synthetic resin material. Such processes are known, for example, from WO 2012 / 149590 A1 and US 6,060,631 A.

[0052] Synthetic crude oil obtained from synthetic resin materials typically contains many different impurities, particularly wax carboxylic acids, polycyclic amines, and neutral compounds, which can be removed particularly well by the method according to the present invention. This is especially true for synthetic resin waste, which usually contains mixtures of various synthetic resins. Furthermore, synthetic resin materials typically contain additives that can result in impurities in the form of organophosphates or phosphonates. Such phosphates or phosphonates can be hydrolyzed under basic conditions in the method according to the present invention and can therefore be removed particularly efficiently.

[0053] In preferred embodiments, the synthetic resin material comprises at least one of polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyamide (PA), styrene-acrylonitrile (SAN), and acrylonitrile-butadiene-styrene (ABS). The method according to the present invention has been found to be particularly suitable for removing impurities arising from the above-mentioned synthetic resin material.

[0054] It is particularly preferable if the synthetic resin material contains PVC. This typically results in impurities in the form of organochlorine compounds in the crude oil stream obtained from the synthetic resin material. Organochlorine compounds can be removed particularly well by basic hydrolysis during the washing process with the first water-soluble washing solution.

[0055] Furthermore, it is particularly preferable when the synthetic resin material contains PET. This typically introduces impurities in the form of ester compounds into the crude oil stream obtained from the synthetic resin material, which can also be removed particularly well by basic hydrolysis during the washing process with the first water-soluble washing solution.

[0056] In particular, it is preferable that the synthetic resin material contains PA, SAN, and / or ABS. These synthetic resin materials typically result in impurities in the form of amides and nitriles. In the process of the method according to the present invention, these compounds can also be hydrolyzed in the process of washing with a first water-soluble washing solution. Basic compounds formed from basic hydrolysis, particularly amines, can be efficiently removed in subsequent washing with an acidic water-soluble washing solution. PA, SAN, and ABS can also act as nitrogen sources and contribute to the increased generation of polycyclic amines through rearrangement reactions, condensation reactions, and / or radical reactions with, for example, PE, PP, and PS. These can be efficiently removed by washing with the acidic water-soluble washing solutions provided by the present invention.

[0057] All parameters mentioned herein, unless otherwise specified, refer to SATP conditions according to IUPAC ("Standard Ambient Temperature and Pressure"), specifically a temperature of 25°C and a pressure of 101,300 Pa.

[0058] Here, all percentages (%) refer to weight percentages unless otherwise specified.

[0059] Unless otherwise specified, all mixing ratios specified herein refer to volume ratios, i.e., volume-to-volume ratios.

[0060] The temperatures specified herein for the cleaning process preferably refer to the temperature of the mixture of the crude oil flow and the water-soluble cleaning solution immediately after mixing and before phase separation in each case.

[0061] The present invention is illustrated by the following figures, but is not limited thereto. [Brief explanation of the drawing]

[0062] [Figure 1] Figure 1 shows a flow chart of a preferred embodiment of the process according to the present invention for producing synthetic crude oil. [Modes for carrying out the invention]

[0063] In the embodiment shown in Figure 1, the synthetic crude oil flow 1 is obtained by the depolymerization of a synthetic resin material. The synthetic resin material is compressed, degassed, and melted in an extruder 12. The synthetic resin molten material exiting the extruder 12 is mixed in a static mixer 13 with an external solvent 14, preferably heavy fuel oil, and / or already decomposed synthetic resin material which is recycled as a recycled flow 15 to reduce the viscosity of the synthetic resin molten material. The resulting mixture is introduced into a depolymerization reactor 16 in which the synthetic resin material is depolymerized at a temperature preferably 400°C to 440°C. The cracked synthetic resin material is obtained as the top product of column 17. After separating the gas flow 18 in a further column 19, the synthetic crude oil flow 1 is obtained.

[0064] In the illustrated embodiment, the synthetic crude oil stream 1 is mixed with the first water-soluble cleaning solution 2 in the mixing zone of the first mixer-settler 8, preferably in a volume mixing ratio of 1:1. The first water-soluble cleaning solution 2 is preferably a sodium hydroxide solution with a pH of 9 to 12. The mixture of the synthetic crude oil stream 1 and the first water-soluble cleaning solution 2 preferably has a temperature of at least 95°C. Since the synthetic crude oil stream 1 is supplied directly from the manufacturing process to the mixer-settler 8, heating is not required to reach this temperature. The high temperature, in particular, improves the water solubility of wax carboxylic acids that enter the aqueous phase through deprotonation formation due to the basic pH value. Furthermore, the high temperature promotes the hydrolysis of impurities by forming neutral compounds. Acidic hydrolysis products, such as carboxylic acids, are deprotonated due to the basic pH value and pass into the aqueous phase as charged compounds. As a result, the purified oil phase is separated from the aqueous phase in the sedimentation zone of the first mixer-settler 8. The average residence time in the first mixer-settler 8 is preferably 5 to 30 minutes. The aqueous phase is removed as part of the wastewater flow 11, and the oil phase is separated as a first refined synthetic crude oil flow 3.

[0065] The first purified synthetic crude oil stream 3 obtained in this manner is then mixed with a second water-soluble washing solution 4 in a second mixer-settler 9. The second water-soluble washing solution 4 is preferably a sulfuric acid-soluble washing solution with a pH of 0 to 5. Furthermore, the temperature of the mixture of the first purified synthetic crude oil stream 3 and the second water-soluble washing solution 4 is lower than the temperature of the mixture in the first washing step, preferably 90°C or lower. The lower temperature in the second washing step reduces the formation of additional impurities and increases the product recovery rate. Moreover, the requirements for the materials of the second mixer-settler 9 are lower, and in particular, expensive materials and coatings are not required. Furthermore, the second washing can be carried out at lower pressure, which in turn leads to lower requirements for the materials used. In particular, basic impurities such as amines or pyridines are protonated by washing with an acidic water-soluble washing solution and thus pass into the aqueous phase as charged compounds. Furthermore, any remaining neutral compounds can also be hydrolyzed under acidic conditions. Next, the refined oil phase is separated again from the aqueous phase in the settling zone of the second mixer settler 9, the aqueous phase is removed via the wastewater flow 11, and a second stream of refined synthetic crude oil 5 is obtained from the oil phase.

[0066] In the illustrated embodiment, the second refined synthetic crude oil flow 5 is washed with a third water-soluble washing solution 6 in a third mixer-settler 10. The third water-soluble washing solution 6 is preferably a neutral water-soluble washing solution, and preferably essentially water. The temperature in this washing step is preferably the same as or lower than the temperature in the second washing step. This washing step removes impurities, some of which may still be present after the first two washing steps (e.g., acidic hydrolysis products, small polar neutral molecules, and inorganic and organic salts). Neutral washing also enhances safety with respect to further use of the third refined synthetic crude oil flow 7 obtained therefrom. After washing, the aqueous phase is again removed as part of the wastewater flow 11, and the third refined synthetic crude oil flow 7 is obtained from the oil phase.

Claims

1. A method for refining the synthetic crude oil flow (1), The aforementioned synthetic crude oil flow (1) is generated, The aforementioned synthetic crude oil flow (1) is refined, The aforementioned flow of synthetic crude oil (1) includes pyrolysis oil or a fraction of the pyrolysis oil, To obtain a first stream of refined synthetic crude oil (3), the stream of synthetic crude oil (1) is washed with the first water-soluble washing solution (2) at a first temperature so as to separate at least acidic impurities in the stream of synthetic crude oil (1) through the aqueous phase by contact with the first water-soluble washing solution (2). To obtain a second stream of refined synthetic crude oil (5), the first stream of refined synthetic crude oil (3) is washed with the second water-soluble washing solution (4) at a second temperature so as to separate basic impurities in the first stream of refined synthetic crude oil (3) through contact with the second water-soluble washing solution (4) via the aqueous phase. A method characterized in that the first water-soluble cleaning solution (2) is basic, the second water-soluble cleaning solution (4) is acidic, the temperature of the second solution is lower than the temperature of the first solution, and the temperature of the first solution is 100°C or higher.

2. The method according to claim 1, characterized in that the first temperature is 105°C or higher.

3. The method according to claim 1 or 2, characterized in that the cleaning of the synthetic crude oil flow (1) with the first water-soluble cleaning solution (2) is carried out with an average cleaning time of at least 0.5 minutes.

4. The method according to 1 or 2, characterized in that the washing of the synthetic crude oil flow (1) with the first water-soluble washing solution (2) is performed at a higher pressure than the washing of the first refined synthetic crude oil flow (3) with the second water-soluble washing solution (4).

5. The method according to claim 1 or 2, characterized in that the pH value of the first water-soluble washing solution (2) is 8 or higher.

6. The method according to claim 1 or 2, characterized in that the pH value of the second water-soluble washing solution (4) is 6 or less.

7. The method according to claim 1 or 2, characterized in that the volume mixing ratio of the synthetic crude oil flow (1) and the first water-soluble cleaning solution (2) is 5:1 to 1:

5.

8. The method according to claim 1 or 2, characterized in that no cleaning step is performed between the cleaning of the synthetic crude oil flow (1) with the first water-soluble cleaning solution (2) and the cleaning of the first refined synthetic crude oil flow (3) with the second water-soluble cleaning solution (4).

9. The method according to claim 1 or 2, further comprising washing the second stream of refined synthetic crude oil (5) with a third water-soluble washing solution (6) at a third temperature in order to obtain a third stream of refined synthetic crude oil (7).

10. The method according to claim 9, characterized in that the pH value of the third water-soluble washing solution (6) is in the range of 3 to 13.

11. The method according to claim 9, characterized in that the third temperature is lower than the first temperature.

12. The method according to claim 9, characterized in that the cleaning of the synthetic crude oil flow (1) with the first water-soluble cleaning solution (2) is performed at a higher pressure than the cleaning of the second refined synthetic crude oil flow (5) with the third water-soluble cleaning solution (6).

13. The method according to claim 9, characterized in that the volume mixing ratio of the second stream of refined synthetic crude oil (5) and the third water-soluble washing liquid (6) is 10:1 to 1:

5.

14. The method according to claim 1, characterized in that the pyrolysis oil is obtained from biomass or synthetic resin.

15. The method according to claim 14, characterized in that the biomass is wood.

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