Method for purifying flow of synthetic crude oil

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 process for refining a synthetic crude stream. [Background technology]

[0002] Synthetic crude oil, sometimes called syncrude, can be obtained from a variety of methods. For example, synthetic crude oil can be shale oil, obtained from oil shale by thermal cracking. Another source is hydrocarbons obtained from oil sands, especially bitumen, from which synthetic crude oil can be obtained by upgrading. Additionally, synthetic crude oil can also be produced from synthetic resin materials, such as synthetic resin waste, by cracking.

[0003] Synthetic crude oils typically contain a variety of impurities that can adversely affect refining processes and plants, and may render the crude oil completely unsuitable for certain refining methods. The type and amount of impurities can vary significantly depending on the source and method by which the synthetic crude oil is obtained.

[0004] WO 2020 / 020769 A1 describes a method for purifying recyclable or renewable organic materials, which comprises heating the material in the presence of an aqueous alkali metal hydroxide liquid and hydrotreating it 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 the treatment of liquefied synthetic resin waste, which comprises pretreatment of liquefied synthetic resin waste with an aqueous medium having a pH value of at least 7 at a temperature of at least 200°C, followed by hydrotreatment and post-treatment to obtain a feed for a steam cracker.

[0006] WO 2014 / 165859 A1 describes a method and apparatus for processing synthetic crude oil, in which the synthetic crude oil is washed with a basic process aqueous wash solution to reduce the acidity level. The method may also include two or more wash steps.

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

[0008] However, conventional refining methods are often complex and / or inadequate. In particular, impurities, such as neutral compounds (esters, aldehydes, ketones, organic halogen compounds, amides, nitriles, etc.) and polycyclic amines, are often insufficiently or not removed at all. This is particularly problematic in the case of complex starting materials, where the impurity profile can vary greatly, as in the case of synthetic crude oils obtained from synthetic resin waste. Inadequately removed impurities can then cause problems in the further processing of the refined crude oil. Another problem is the formation of deposits in plants observed during many refining processes, which makes the plants more difficult to clean and hinders efficient operation. Summary of the Invention

[0009] Therefore, there remains a need for new or improved methods for the refining of synthetic crude oils. It is an object of the present invention to provide such methods. In particular, it is an object of the present invention to provide a method for refining synthetic crude oils that allows for particularly efficient and thorough removal of impurities, especially impurities in the form of acidic or basic compounds, as well as neutral 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 object is achieved by a method for refining a synthetic crude oil stream, the method comprising the steps of: synthetic crude oil supplies; Washing the synthetic crude stream with a first aqueous wash fluid at a first temperature to obtain a first refined synthetic crude stream; washing the first refined synthetic crude stream with a second aqueous wash fluid at a second temperature to obtain a second refined synthetic crude stream, the first aqueous wash fluid being basic and the second aqueous wash fluid being acidic, and the second temperature being lower than the first temperature.

[0011] In a further aspect, the present invention relates to a method for producing a synthetic crude oil comprising the steps of: Preferably, depolymerization of synthetic resin material, especially synthetic resin waste, to produce a synthetic crude stream; and refining the synthetic crude stream by the method for refining a synthetic crude stream according to the present invention.

[0012] In the course of the present invention, it has surprisingly been found advantageous to carry out a basic wash step at a higher temperature followed by an acidic wash step at a lower temperature. The surprising advantage arises from both the fact that the basic wash step is carried out before the acidic wash step and the fact that the temperature of the basic wash step is higher than that of the acidic wash step.

[0013] Regarding the order of wash steps, we have surprisingly found that performing a basic wash step before an acid wash step can result in significantly reduced sediment as well as better phase separation. When performing an acid wash step without a prior basic wash, we observed the formation of sediment, which we found to be primarily deposited wax carboxylic acids. Wax carboxylic acids are long-chain carboxylic acids, e.g., with chain lengths between 20 and 75 carbon atoms. Wax carboxylic acids may contain aromatic, olefinic, and heteroatomic functionality in addition to paraffinic, unbranched, and branched chains. Wax carboxylic acids are present in many synthetic crude oils, particularly pyrolysis oils (e.g., from the pyrolysis of synthetic resins). This is because these compounds can increasingly be formed during the pyrolysis process, for example, from reactions with introduced oxygen or by pre-existing functional polymers or additives. In synthetic crude oils, wax carboxylic acids are often present in a bound state as salts. In the process of the present invention, we have found that treating an unreprocessed synthetic crude oil stream with an acidic aqueous wash solution protonates and thus releases bound wax carboxylic acids. It has been shown that the wax carboxylic acids released in this way can, on the one hand, deposit and form unwanted deposits, and, on the other hand, act as surfactants, form mixed phases, or bind unwanted compounds such as water, heavy metals, and nitrogen compounds in the oil phase. Furthermore, unremoved wax carboxylic acids can also cause corrosion in plants and act as catalyst poisons in the subsequent further 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 aqueous washing solution, the wax carboxylic acids are present mainly in a deprotonated state and can be removed through the aqueous phase, thereby reducing the adverse effects of the subsequent acidic washing step. The sequence of washing with the first aqueous washing solution and the second aqueous washing solution provided by the present invention can therefore result in reduced deposits in the plant, better phase separation, and therefore better removal of impurities, reduced corrosion in the plant, and protection of the catalyst during further processing.

[0015] Furthermore, performing the basic wash step at elevated temperatures has been shown to be advantageous for the removal of wax carboxylic acids. High temperatures result in better solubility of wax carboxylic acids in the aqueous phase. Therefore, it is advantageous if the wash of the synthetic crude oil stream with the first aqueous wash solution is carried out at temperatures above 70°C. Temperatures above 95°C have been found to be particularly advantageous, since many salts of wax carboxylic acids, especially alkali salts, are particularly soluble in water at these temperatures and can be removed particularly efficiently via the aqueous phase.

[0016] Traditionally, basic aqueous washes have been used primarily to reduce the acid level in synthetic crude oil. It has been discovered that basic aqueous washes can even be used to remove neutral compounds such as esters, aldehydes, ketones, organohalogen compounds, amides, and nitriles. In the method of the present invention, such neutral compounds can be hydrolyzed by the first aqueous wash. The basic hydrolysis products include acidic compounds, such as carboxylic acids, which are removed during the basic wash, as well as basic compounds, such as amines, which can be removed in a subsequent acid wash step.

[0017] This provides an additional advantage if the basic wash step is carried out at a higher temperature. While acidic compounds such as carboxylic acids and phenols only need to be deprotonated during the basic wash in order to be removed with the aqueous wash solution, neutral compounds that cannot be deprotonated under the wash conditions must undergo a hydrolysis reaction. The hydrolysis reaction is temperature-dependent and proceeds more quickly at higher temperatures. Therefore, the higher the temperature of the basic wash step, the better the removal of neutral compounds. In this context, it is preferred if the washing of the synthetic crude oil stream with the first aqueous wash solution is carried out at a temperature above 70°C. Even higher temperatures, such as above 95°C, and especially above 100°C, have proven particularly suitable for the removal of neutral compounds.

[0018] In addition to removing hydrolysis products from the basic wash step, washing the first refined synthetic crude oil stream with the acidic aqueous wash solution provided in the method of the present invention allows for the removal of additional 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 present in greater amounts in synthetic crude oil, especially pyrolysis oil. They can be formed during cracking processes, for example, in the presence of nitrogen sources, such as additives, or polymers such as polyamide (PA), polyacrylonitrile (PAN), or acrylonitrile-butadiene-styrene copolymer (ABS). In the case of polycyclic amines, they can be, for example, polycondensed saturated, mono- and polyunsaturated, or aromatic ring systems. They can partially dissolve in synthetic crude oil or float in the colloidal region, often resulting in undesirable deposits and thus more difficult plant cleaning. Furthermore, they can lead to blocking of the active surface of catalysts in subsequent applications. Furthermore, they are capable of dissolving 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 method according to the invention. For the removal of polycyclic amines, it has proven advantageous if 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, during the course of the invention, it has proven surprisingly advantageous if the temperature in the acid wash step is not too high, particularly if it is lower than the temperature in the basic wash step. It has been found that high temperatures in the acid wash step can result in reduced product recovery and the formation of impurities. In the inventors' view, without being bound by theory, this can be explained by the reaction of the olefin with the acid used, for example, by hydroxysulfonation or sulfation with sulfuric acid, or by reaction with other acids. Alcohols, sulfonates, sulfates, and hydroxysulfonates can form as impurities, which can lead to deposits and therefore more difficult cleaning and corrosion. Therefore, it has proven advantageous to perform the acid wash step at a temperature of 120°C or less. These adverse effects can be minimized, particularly if the temperature is 100°C or less, and more preferably 95°C or less.

[0020] A further advantage of the lower temperatures in the acidic cleaning step is that the demands on the materials of the cleaning equipment are significantly lower: the presence of acidic solutions at high temperatures often requires the use of special materials or coatings, which would result in a significant increase in costs.

[0021] A further advantage of the sequential washing steps in the process of the present invention is that the process can be carried out particularly economically, especially in connection with preferred embodiments in which the basic and acidic washing steps are part of a continuous process. Syncrude oil is typically obtained from high-temperature processes, such as pyrolysis or cracking. If the production process of the present invention is downstream of such processes, heating of the syncrude oil stream is not required if the basic washing step is carried out before the acidic washing step. The syncrude oil stream obtained from the production process can be washed with a first aqueous wash solution directly or after cooling to a first temperature, and the first refined syncrude oil stream obtained therefrom can be washed with a second aqueous wash solution after further cooling to a second temperature. Due to the fact that the syncrude oil stream does not need to be heated between washing steps, the process can be carried out particularly economically and efficiently. Therefore, it is particularly preferred in connection with the process of the present invention if the syncrude oil stream is not heated between washing at the first temperature and washing at the second temperature.

[0022] In a preferred embodiment of the process according to the invention, the first temperature is at least 70°C, preferably at least 80°C, more preferably at least 90°C, more preferably at least 95°C, even more preferably at least 100°C, even more preferably at least 105°C, even more preferably at least 110°C, even more preferably at least 115°C, even more preferably at least 120°C, even more preferably at least 125°C, even more preferably at least 130°C, and most preferably at least 135°C. Providing such a high first temperature has the advantage that wax carboxylic acids present in the syncrude stream can be better dissolved and removed by the basic wash. A further advantage of a high first temperature is that the basic hydrolysis reaction proceeds particularly rapidly, thus allowing for particularly good removal of neutral compounds. It is particularly preferred if the first temperature is in the range of from 70°C to 190°C, preferably from 80°C to 180°C, more preferably from 90°C to 170°C, even more preferably from 95°C to 165°C, even more preferably from 100°C to 160°C, even more preferably from 105°C to 155°C, even more preferably from 110°C to 150°C, and most preferably from 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 less, preferably 110°C or less, more preferably 100°C or less, even more preferably 95°C or less, even more preferably 90°C or less, even more preferably 80°C or less, and most preferably 75°C or less. Providing such lower temperatures has the advantage of reducing the formation of impurities and increasing product yield. An additional advantage of lower temperatures is that the cleaning equipment is exposed to more severe conditions, thus requiring less expensive materials or material coatings. At the same time, basic compounds such as amines and pyridines can still be efficiently removed, since, in contrast to neutral compounds, protonation alone does not require a hydrolysis reaction to remove these compounds. It is particularly preferred for the second temperature to be in the range of 20°C to 120°C, preferably in the range of 30°C to 110°C, more preferably in the range of 40°C to 100°C, even more preferably in the range of 50°C to 90°C, even more preferably in the range of 60°C to 80°C, and even more preferably in the range of 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, in particular, polycyclic amines.

[0024] In a preferred embodiment, washing of the synthetic crude oil stream with the first aqueous wash solution is carried out for an average wash 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 wash time for the basic wash allows for more complete progression of the hydrolysis reaction, resulting in better removal of neutral compounds. This is particularly preferred when the average wash duration is between 0.5 and 180 minutes, 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.

[0025] The average wash duration is preferably the average time between contacting the syncrude stream with the first aqueous wash fluid and separating the first refined syncrude stream from the first aqueous wash fluid. If washing is carried out in a continuous process, the average wash duration preferably corresponds to the average residence time of the wash equipment, for example, in a mixer-settler.

[0026] In a preferred embodiment, the washing of the syncrude stream with the first aqueous wash is conducted at a higher pressure than the washing of the first refined syncrude stream with the second aqueous wash. Providing higher pressure during the basic wash allows for higher temperatures and therefore better removal of poorly soluble wax carboxylic acids as well as neutral compounds. In contrast, lower pressures are advantageous in the acid wash because they can reduce the formation of unwanted impurities and can result in significant cost savings due to lower material requirements.

[0027] In a preferred embodiment, washing of at least the syncrude stream with the first aqueous wash solution is carried out in a pressure vessel, which allows for higher pressure and temperature washes and therefore better removal of neutral compounds as well as poorly soluble wax carboxylic acids.

[0028] Preferably, washing of the synthetic crude oil stream with the first aqueous wash liquid is carried out at a pressure of 2 bar or more, preferably 3 bar or more, more preferably 5 bar or more, even more preferably 7 bar or more, and most preferably 10 bar or more. As mentioned, providing such high pressures allows for high temperatures and good removal of poorly soluble wax carboxylic acids as well as neutral compounds. It is particularly preferred if washing of the synthetic crude oil stream with the first aqueous wash 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, even more preferably 7 bar to 20 bar, and most preferably 10 bar to 18 bar.

[0029] Preferably, washing of the first refined synthetic crude stream with the second aqueous wash liquid is carried out at a pressure of 12 bar or less, preferably 7 bar or less, more preferably 6 bar or less, and even more preferably 5 bar or less. As mentioned, providing such lower pressures allows for the use of less expensive materials. It is particularly preferred if washing of the first refined synthetic crude stream with the second aqueous wash liquid is carried out at a pressure in the range of 1 bar to 12 bar, preferably 1.5 bar to 7 bar, more preferably 2 bar to 6 bar, and even more preferably 3 bar to 5 bar.

[0030] Within the scope of the present invention, it has proven particularly advantageous if the pH value of the first aqueous cleaning liquid is 8 or higher, preferably 9 or higher, more preferably 10 or higher, even more preferably 11 or higher, even more preferably 12 or higher, and most preferably 13 or higher. Such high pH values ​​accelerate the hydrolysis reaction, thereby allowing particularly good removal of neutral compounds. It is particularly preferred if the pH value of the first aqueous cleaning liquid is in the range of 8 to 14, preferably 9 to 13, more preferably 9.5 to 12, and most preferably 10 to 11.

[0031] In a preferred embodiment, the first aqueous cleaning liquid comprises sodium hydroxide. It is particularly preferred if the concentration of sodium hydroxide is between 0.5 and 10 wt %, in particular between 1 and 5 wt %.

[0032] With respect to washing the first refined synthetic crude oil stream with the second aqueous wash solution, it has been found to be particularly advantageous if the second aqueous wash solution has a pH value of 6 or less, preferably 5 or less, more preferably 4 or less, even more preferably 3 or less, even more preferably 2 or less, and most preferably 1 or less, which allows for particularly efficient removal of basic impurities such as amines and pyridines. It is particularly preferred if the pH value of the second aqueous wash solution is in the range of 0 to 6, preferably 1 to 5, more preferably 2 to 4, and most preferably 2.5 to 3.5.

[0033] In a preferred embodiment, the second aqueous cleaning liquid contains sulfuric acid, the concentration of which is preferably 0.5 to 10% by weight, and more preferably 1 to 5% by weight.

[0034] It has proven advantageous if the volumetric mixing ratio between the synthetic crude oil stream and the first aqueous wash liquid is between 5:1 and 1:5, preferably between 2.5:1 and 1:2.5, and even more preferably between 1.5:1 and 1:1.5, which allows both 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 mix ratio between the first refined synthetic crude oil stream and the second aqueous wash liquid 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, which allows for particularly efficient removal of basic impurities.

[0036] The process according to the invention can also be subjected to additional washing steps. For example, the first refined synthetic crude stream can be subjected to additional washing or refining steps before washing with the second aqueous wash fluid. However, it is preferred if no additional refining steps are performed between washing the synthetic crude stream with the first aqueous wash fluid and washing the first refined synthetic crude stream with the second aqueous wash fluid, particularly no washing steps, no filtration steps, and / or no hydrotreating steps. This has the advantage, among other things, that basic products formed from neutral compounds by basic hydrolysis can be removed in an acidic wash step immediately following the basic wash step.

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

[0038] The process according to the invention can also include a hydrotreating step for additional removal of impurities. However, it is preferred if the process according to the invention does not include a hydrotreating step. Avoiding a hydrotreating step results in a particularly simple and economical purification process. The washing step provided by the invention allows particularly good removal of impurities, even if no hydrotreating step is provided at all.

[0039] In a particularly preferred embodiment, the method according to the invention further comprises washing the second refined syncrude stream with a third aqueous wash solution at a third temperature to obtain a third refined syncrude stream. Providing such an additional wash step allows for particularly thorough removal of impurities that may still be present after the basic and acidic wash steps.

[0040] In this regard, it is particularly preferred if the pH value of the third aqueous cleaning liquid 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 for removing small polar neutral molecules as well as inorganic and organic salts. It is particularly advantageous if the third aqueous cleaning liquid is basic or substantially neutral, especially substantially neutral.

[0041] In a preferred embodiment, the third aqueous cleaning solution comprises a neutral amine, which has the advantage of providing better protection for subsequent plant life.

[0042] In a preferred embodiment, the third temperature is lower than the first temperature, thereby eliminating the need to heat the crude oil stream prior to washing with the third aqueous wash fluid, thereby allowing the method to be carried out efficiently and economically.

[0043] Preferably, the third temperature is not more than 120° C., preferably not more than 110° C., more preferably not more than 100° C., even more preferably not more than 90° C., even more preferably not more than 80° C., and most preferably not more than 75° C. It is particularly preferred if the third temperature is in the range of from 20° C. to 120° C., preferably from 30° C. to 110° C., more preferably from 40° C. to 100° C., even more preferably from 50° C. to 90° C., even more preferably from 60° C. to 80° C., and even more preferably from 65° C. to 75° C.

[0044] It has been proven advantageous to wash the synthetic crude oil stream with the first aqueous wash at a higher pressure than to wash the second refined synthetic crude oil stream with the third aqueous wash. Providing higher pressure during the basic wash allows for higher temperatures and therefore more thorough removal of neutral compounds as well as poorly soluble wax carboxylic acids. However, when washing with the third aqueous wash, lower pressure is advantageous because it reduces the material requirements used, which can result in significant cost savings.

[0045] In a preferred embodiment, washing of the second refined synthetic crude stream with the third aqueous wash 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 proven advantageous if the volumetric mixing ratio between the second refined synthetic crude oil stream and the third aqueous wash liquid is between 10:1 and 1:5, preferably between 5:1 and 1:2.5, and even more preferably between 2.5:1 and 1:1.5, which allows for a particularly efficient removal of remaining impurities.

[0047] In the context of the present invention, it is preferred if the process for refining the synthetic crude oil stream is a continuous process. Compared to batch processes, this has the advantage of achieving higher productivity and shorter downtimes. Preferably, the steps of washing the synthetic crude oil stream with a first aqueous wash liquid, washing the first refined synthetic crude oil stream with a second aqueous wash liquid, and, if provided, washing the second refined synthetic crude oil stream with a third aqueous wash liquid are therefore part of a continuous process. It is also preferred if the process according to the present invention for producing synthetic crude oil is a continuous process, i.e., if the production of the synthetic crude oil stream, preferably by depolymerization of a synthetic resin material, is also part of a continuous process. Providing a continuous process has the advantage, in particular, of avoiding heating of the synthetic crude oil stream, since the synthetic crude oil stream obtained from the production process can be washed with the first aqueous wash liquid directly or after cooling to the first temperature, or the first refined synthetic crude oil stream can be washed with the second aqueous wash liquid after cooling from the first temperature to a second temperature.

[0048] Typically, washing a crude oil stream with an aqueous wash fluid involves mixing the crude oil stream with the aqueous wash fluid and then separating the refined crude oil stream from the aqueous wash fluid.

[0049] Preferably, the washing steps of the process according to the invention are carried out in a mechanical mixer, a static mixer and / or a mixer-settler. It has proven particularly advantageous if the washing steps of the process according to the invention are each carried out in a mixer-settler. Typically, a mixer-settler comprises a continuously operated mixing zone and a continuously operated settling zone, thus allowing mixing of the syncrude stream with the respective aqueous wash liquid, as well as a subsequent settling process in which the phases are separated and the refined syncrude stream is separated in a continuous process.

[0050] In the context of the present invention, the term "synthetic crude stream" preferably refers to a stream of material containing synthetic crude oil or a fraction thereof. The synthetic crude stream preferably consists of synthetic crude oil or a fraction thereof. Within the scope of the present invention, it is particularly preferred if the synthetic crude stream comprises, and in particular consists of, a pyrolysis oil or a fraction thereof. Preferably, the pyrolysis oil is a pyrolysis oil obtained from biomass, in particular wood and / or synthetic resins. The process according to the present invention has proven particularly suitable when the synthetic crude stream is a hydrocarbon mixture obtained from the depolymerization of biomass or synthetic resin materials, in particular synthetic resin materials. Therefore, the synthetic crude stream is preferably a synthetic resin pyrolysate or a fraction thereof, or a biomass pyrolysate, in particular a wood pyrolysate or a fraction thereof. However, the process according to the present invention is also well suited to other synthetic crude oils and fractions thereof. In a further preferred embodiment, the synthetic crude stream preferably consists of shale oil or modified bitumen.

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

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

[0053] In a preferred embodiment, 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 invention has been found to be particularly suitable for removing impurities originating from the above synthetic resin materials.

[0054] This is particularly preferred when the synthetic resin material contains PVC, which typically results in impurities in the form of organochlorine compounds in the crude oil stream obtained from the synthetic resin material. These organochlorine compounds can be particularly well removed by basic hydrolysis during washing with the first aqueous wash solution.

[0055] This is also particularly preferred when the synthetic resin material comprises PET, which typically results in impurities in the form of ester compounds in the crude oil stream obtained from the synthetic resin material, which can also be particularly well removed by basic hydrolysis during washing with the first aqueous wash solution.

[0056] It is particularly preferred when the synthetic resin material contains PA, SAN, and / or ABS. These synthetic resin materials typically produce impurities in the form of amides and nitriles. In the process of the present invention, these compounds can also be hydrolyzed during washing with the first aqueous washing solution. The basic compounds, especially amines, formed from the basic hydrolysis can be efficiently removed by subsequent washing with an acidic aqueous washing solution. PA, SAN, and ABS can also serve as nitrogen sources, contributing to the increased production 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 aqueous washing solution provided by the present invention.

[0057] All parameters mentioned herein refer to SATP conditions according to IUPAC ("standard ambient temperature and pressure"), in particular a temperature of 25°C and a pressure of 101,300 Pa, unless otherwise indicated.

[0058] All percentages (%) herein refer to weight percent unless otherwise indicated.

[0059] Unless otherwise indicated, all mix ratios specified herein refer to volume mix ratios, i.e., volume:volume ratios.

[0060] The temperatures specified herein for the washing steps preferably refer in each case to the temperature of the mixture of crude oil stream and aqueous wash liquid immediately after mixing and before phase separation.

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

[0062] [Figure 1] FIG. 1 shows a process flow diagram of a preferred embodiment of a process according to the present invention for producing synthetic crude oil. DETAILED DESCRIPTION OF THE INVENTION

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

[0064] In the illustrated embodiment, synthetic crude oil stream 1 is mixed with first aqueous wash liquid 2 in the mixing zone of the first mixer-settler 8, preferably at a volumetric mixing ratio of 1:1. First aqueous wash liquid 2 is preferably a sodium hydroxide solution having a pH value of 9 to 12. The mixture of synthetic crude oil stream 1 and first aqueous wash liquid 2 preferably has a temperature of at least 95°C. Because synthetic crude oil stream 1 is fed directly from the manufacturing process to the mixer-settler 8, no heating is required to reach this temperature. In particular, high temperatures improve the water solubility of wax carboxylic acids, which enter the aqueous phase as deprotonated compounds due to the basic pH. Furthermore, high temperatures promote the hydrolysis of impurities, forming neutral compounds. Acidic hydrolysis products, such as carboxylic acids, are deprotonated due to the basic pH and pass into the aqueous phase as charged compounds. As a result, the refined oil phase is separated from the aqueous phase in the settling 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 wastewater stream 11 and the oil phase is separated as first refined synthetic crude stream 3 .

[0065] The first refined synthetic crude oil stream 3 thus obtained is then mixed with a second aqueous wash solution 4 in a second mixer-settler 9. The second aqueous wash solution 4 is preferably a sulfuric acid aqueous wash solution with a pH value of 0 to 5. Furthermore, the temperature of the mixture of the first refined synthetic crude oil stream 3 and the second aqueous wash solution 4 is lower than that of the mixture in the first wash step, preferably below 90°C. The lower temperature in the second wash step reduces the formation of additional impurities and increases product recovery. Furthermore, the second mixer-settler 9 has lower material requirements, particularly without the need for expensive materials and coatings. Furthermore, the second wash can be carried out at lower pressures, 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 the acidic aqueous wash solution and therefore pass into the aqueous phase as charged compounds. Furthermore, remaining neutral compounds can also be hydrolyzed under acidic conditions. The refined oil phase is then separated again from the aqueous phase in the settling zone of the second mixer-settler 9, the aqueous phase being removed via wastewater stream 11, and a second refined synthetic crude oil stream 5 being obtained from the oil phase.

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

Claims

1. 1. A process for refining a synthetic crude oil stream (1), comprising: producing said synthetic crude stream (1); refining said synthetic crude stream (1); the synthetic crude oil stream (1) comprises a pyrolysis oil or a fraction of the pyrolysis oil; washing said synthetic crude oil stream (1) with a first aqueous wash liquid (2) at a first temperature to obtain a first refined synthetic crude oil stream (3); washing said first refined syncrude stream (3) with a second aqueous wash fluid (4) at a second temperature to obtain a second refined syncrude stream (5); 1. A method according to claim 1, wherein the first aqueous cleaning liquid (2) is basic and the second aqueous cleaning liquid (4) is acidic, the second temperature is lower than the first temperature, and the first temperature is equal to or higher than 100°C.

2. 2. The method of claim 1, wherein the first temperature is 105°C or greater.

3. 3. The method according to claim 1 or 2, characterized in that the washing of the synthetic crude oil stream (1) with the first aqueous washing liquid (2) is carried out for an average washing time of at least 0.5 minutes.

4. 3. The method of claim 1, wherein washing the synthetic crude oil stream (1) with the first aqueous wash fluid (2) is carried out at a higher pressure than washing the first refined synthetic crude oil stream (3) with the second aqueous wash fluid (4).

5. 3. The method according to claim 1 or 2, characterized in that the pH value of the first aqueous cleaning liquid (2) is 8 or higher.

6. 3. The method according to claim 1 or 2, characterized in that the pH value of the second aqueous cleaning liquid (4) is less than or equal to 6.

7. 3. The method according to claim 1 or 2, characterized in that the volumetric mixing ratio of the synthetic crude oil stream (1) to the first aqueous wash liquid (2) is between 5:1 and 1:

5.

8. 3. The method according to claim 1 or 2, characterized in that no washing step is carried out between washing the synthetic crude oil stream (1) with the first aqueous washing liquid (2) and washing the first refined synthetic crude oil stream (3) with the second aqueous washing liquid (4).

9. 3. The method of claim 1 or 2, further comprising washing the second refined syncrude stream (5) with a third aqueous wash fluid (6) at a third temperature to obtain a third refined syncrude stream (7).

10. 10. The method according to claim 9, characterized in that the pH value of the third aqueous cleaning liquid (6) is in the range of 3 to 13.

11. 10. The method of claim 9, wherein the third temperature is lower than the first temperature.

12. 10. The method of claim 9, wherein washing of the synthetic crude oil stream (1) with the first aqueous wash liquid (2) is carried out at a higher pressure than washing of the second refined synthetic crude oil stream (5) with the third aqueous wash liquid (6).

13. 10. The method of claim 9, wherein the volumetric mix ratio of the second refined synthetic crude oil stream (5) to the third aqueous wash liquid (6) is between 10:1 and 1:

5.

14. 2. The method according to claim 1, wherein the pyrolysis oil is a pyrolysis oil obtained from biomass or synthetic resin.

15. 15. The method of claim 14, wherein the biomass is wood.

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