Method for Reducing Impurities in a Hydrocarbon-Comprising Composition

Abstract

A method for reducing at least one impurity in a hydrocarbon-comprising composition, the method comprising the following steps: providing, in a composition provision step, a hydrocarbon-comprising composition; providing, in a pyrolysis coke provision step, a pyrolysis coke, wherein the pyrolysis coke comprises at least one catalytically active component; in a contact step, contacting the pyrolysis coke with the hydrocarbon-comprising composition.

Description

Method for Reducing Impurities in a Hydrocarbon-Comprising CompositionTechnical FieldThe present invention relates to a method for reducing impurities in a hydrocarbon-comprising composition, as well as the use of pyrolysis coke for reducing impurities in a hydrocarbon-comprising composition.Prior ArtThe chemical recycling of plastics - such as those found in mixed plastic waste - via pyrolysis is gaining increasing interest, as it has the potential to complement conventional mechanical recycling processes to achieve the policy goals of a circular economy for plastics.The theoretical approach of producing steam cracker-compatible feedstocks from low-grade waste has not yet been implemented in commercially viable plants, and it remains questionable whether this route is economically and environmentally sustainable.To bypass the steam cracker route and thereby avoid high energy consumption and a larger ecological footprint, and thus be more sustainable, the state of the art proposes producing bulk aromatic chemicals directly from mixed plastic waste. Patent application EP 3 744 814 A1 describes that gaseous pyrolysis products can be catalytically converted into high-value monocyclic aromatic compounds such as BTEX and styrene. However, this process employs technical catalysts such as metal-impregnated zeolites. A disadvantage of this process, however, is that such catalysts can hardly be recovered or regenerated due to the high levels of impurities in the decomposition products of mixed plastic waste.Another, albeit less efficient, option for chemical recycling is to convert the pyrolysis oils in a steam cracker into bulk chemicals such as ethylene and propylene. Due to the high level of contaminants such as halogens, phosphorus, and other elements, (raw) pyrolysis oils from mixed plastic waste or other sources such as biogenic raw materials are only of limited suitability. One drawback of this process is the need for extensive pretreatment steps to, on the one hand, remove undesirable contaminants such as halogens, phosphorus, and other elements (e.g., hydrogenation) and, on the other hand, separate aromatic from aliphatic compounds. The specifications of existing steam crackers as well as subsequent synthesis steps require narrow concentration ranges regarding the content of halogens, phosphorus, and other elements, as well as a limited concentration of aromatic compounds.The final route, which is still commonly used today, is thermal recovery, in which the feedstock is incinerated. This process has the disadvantage that no material recovery is possible, and thus it cannot be part of a sustainable circular economy. Furthermore, it generates a significant amount of climate-damaging emissions, making the process unsustainable.Summary of the InventionThe objective of the present invention is to provide a process that eliminates the disadvantages of the prior art described above. In particular, it is an objective of the present invention to provide a process that produces high-quality aromatic compounds from carbon-comprising waste, removes impurities from the product, is suitable for use in a circular economy, is sustainable, and does not require complex subsequent steps such as purification and / or catalyst recovery.Surprisingly, it has now been discovered that the above-mentioned problem is solved by a process for reducing at least one impurity in a hydrocarbon-comprising composition, wherein the process comprises the following steps: providing, in a composition provision step, a hydrocarbon-comprising composition; providing, in a pyrolysis coke provision step, a pyrolysis coke, wherein the pyrolysis coke comprises at least one catalytically active component; contacting, in a contact step, the pyrolysis coke with the hydrocarbon-comprising composition.Furthermore, it has now been surprisingly discovered that the above-mentioned problem is solved by using a pyrolysis coke to reduce at least one impurity in a hydrocarbon-comprising composition, wherein the pyrolysis coke comprises at least one catalytically active component.Brief Description of the DrawingsFigure 1 shows a schematic representation of the pyrolysis plant as used in the examples.Figure 2 shows the pyrolysis plant used in the examples.Figure 3 shows the experimental setup as used in the examples.Figure 4 shows a schematic of the experimental setup used in the examples.List of reference symbolsFigure 11 Inert gas bottle2 Manual valve3 Manual valve4 Collection vessel for pyrolysis coke5 Pyrolysis reactor6 Connector7 Tar filter8 First spiral cooler9 Second spiral cooler10 3-way valve11 First wash bottle with NaOH12 Second wash bottle with n-hexane13 3-way valve14 Activated carbon filter with vent to the outside air15 Safety valve16 Filling lance17 Ball valve18 Round rod19 Stirring rod20 Heating surfacesFigure 41 Insulation2 Coke bed3 Inlet4 Nitrogen bottle5 Pyrolysis oil storage tank6 Metering pump7 Heating coil8 Cooler9 Cooling connection10 Product collection tankDetailed description of the inventionAs described above, the present invention relates to a method and a use. These are now described in more detail below.MethodAs described above, the present invention relates to a method for reducing at least one impurity in a hydrocarbon-comprising composition, wherein the method comprises the following steps:Providing, in a composition preparation step, a hydrocarbon-comprising composition;providing, in a pyrolysis coke provision step, a pyrolysis coke, wherein the pyrolysis coke comprises at least one catalytically active component;Contacting, in a contact step, the pyrolysis coke with the hydrocarbon-comprising composition.The advantage of this process is that, compared to the prior art, the proportion of high-quality aromatics in the product has been increased while simultaneously significantly reducing the proportion of impurities in the product. Without wishing to be bound by any theory, it is presumed that this effect is attributable to the pyrolysis coke comprising a catalytically active component. Consequently, no costly subsequent purification steps are necessary. Since at least one catalytically active component is present in the pyrolysis coke, it is also not necessary to recover a catalyst from the product. Furthermore, the process is sustainable due to the use of pyrolysis coke and can be integrated into a circular economy for material recovery.a) Pyrolysis coke preparation stepTypically, the pyrolysis coke preparation step involves pyrolysis. Pyrolysis serves to thermochemically convert carbon-comprising feedstocks into liquid pyrolysis concentrate (pyrolysis oil), solid pyrolysis coke, and pyrolysis gas as pyrolysis products and takes place in the absence of oxygen or at least essentially without the presence of oxygen. The proportions and quality of the pyrolysis products are influenced, on the one hand, by the choice of feedstock (and in particular by its residual moisture), but above all by the prevailing process conditions. In this context, the pyrolysis temperature, the residence time in the pyrolysis zone, and any subsequent processing steps are particularly noteworthy.Preferably, the pyrolysis coke is produced from the starting material by pyrolysis. Typically, pyrolysis yields pyrolysis gas, pyrolysis oil, preferably still in a gaseous state, and pyrolysis coke.Preferably, the starting material comprises a polymer and / or a mixture of polymers. It is particularly preferred that the starting material consists of a polymer and / or a mixture of polymers.Preferably, the polymers are selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyvinyl chloride (PVC), polyamide (PA), and polyethylene terephthalate (PET).In a particularly preferred embodiment of the invention, the starting material comprises 25 to 35 wt.-%, preferably 28 to 34 wt.-%, polyethylene, 10 to 30 wt.-%, preferably 12 to 29 wt.-%, polypropylene, 1 to 10 wt.-%, preferably 2 to 5 wt.-%, polystyrene, 1 to 10 wt.-%, preferably 2 to 6 wt.-%, polyvinyl chloride, 2 to 10 wt.-%, preferably 4 to 9 wt.-%, polyamide, and 5 to 20 wt.-%, preferably 8 to 14 wt.-%, polyethylene terephthalate.Pyrolysis is typically carried out at temperatures in the range of 350 to 700 °C and under a system pressure in the range of 1 to 2 bar, preferably in an oxygen-free atmosphere (particularly preferably in nitrogen).The pyrolysis coke produced in this pyrolysis step exhibits certain properties that can act similarly to a catalyst or an adsorbent or absorbent.Primarily, the pyrolysis coke comprises a catalytically active component. The catalytically active component preferably comprises at least one element, preferably consists of it, wherein the at least one element is selected from the group consisting of Si, Al, Ca, Fe, Ti, Na, Mg, Zn, Mn, Ni, Ba, Cr, Cu, B, or Sn. It is particularly preferred that the at least one element be selected from the group consisting of Si, Al, Ca, Fe, Ti, Zn, Mg, Na, and Ca. It is especially preferred that the at least one element be Ca.Preferably, the catalytically active component comprises 1.0 to 35.0 wt.-%, preferably 15.0 to 30.0 wt.-%, of Ca, 0.1 to 20.0 wt.-%, preferably 5.0 to 15.0 wt.-%, Si, 0.1 to 25.0 wt.-%, preferably 10.0 to 20.0 wt.-%, Al, 0.1 to 10.0 wt.-%, preferably 1.0 to 5.0 wt.-%, Zn, 0.1 to 10.0 wt.-%, preferably 0.5 to 5.0 wt.-%, Fe, 0.1 to 10.0 wt.%, preferably 0.5 to 5.0 wt.%, Cu, 0.1 to 5.0 wt.%, preferably 1.0 to 3.0 wt.%, Ti, and / or 0.01 to 1.5 wt.%, preferably 0.1 to 1.0 wt.%, Ba.Preferably, the at least one element in the catalytically active component is present in an activated form, preferably an oxidized form, a reduced form, a sulfured form, a chlorinated form, or a mixture thereof.The catalytically active component is present in the pyrolysis coke in a proportion of 0.1 to 50 wt.-%, preferably 0.5 to 20 wt.-%, based on the total mass of the pyrolysis coke.Preferably, the pyrolysis coke has a pore volume of more than 0.001 cm2 / g, more preferably of more than 0.01 cm3 / g, measured according to DIN ISO 9277-2014-01. Typically, the pore volume of the pyrolysis coke is no higher than 0.1 cm3 / g.Likewise, the pyrolysis coke preferably has a pore size of more than 5 nm, more preferably of more than 8 nm, and particularly preferably of more than 10 nm, measured according to DIN ISO 9277 - 2014-01. Typically, the pore size of the pyrolysis coke is not greater than 50 nm .Preferably, the pyrolysis coke has a specific surface area of more than 1.0 m2 / g, more preferably more than 2 m2 / g, and most preferably more than 4.5 m2 / g, measured according to DIN ISO 9277-2014-01. Typically, the specific surface area of the pyrolysis coke is no greater than 10 m2 / g.b) Contact stepIn the contact step, the hydrocarbon-comprising composition is brought into contact with the pyrolysis coke as the active component.This contact can be achieved, for example, by passing the hydrocarbon-comprising composition through the pyrolysis coke. It is also conceivable that pyrolysis coke is simply stirred into the hydrocarbon-comprising composition. However, passing the composition through the coke is preferred, as a continuous process offers advantages in terms of efficiency and can be better integrated into existing systems.Preferably, the hydrocarbon-comprising composition is liquid at 20 °C and 1 bar. It is particularly preferred that the hydrocarbon-comprising composition be selected from the list consisting of petrochemical intermediates, waste oil, and pyrolysis oil, most preferably, the hydrocarbon-comprising composition comprises or consists of pyrolysis oil.In the contact step, it is preferred that, in addition to the pyrolysis coke, no other component comprising a catalytically active component is used, wherein the catalytically active component comprises at least one element, preferably consists of it, and wherein the at least one element is preferably selected from the group consisting of Si, Al, Ca, Fe, Ti, Na, Mg, Zn, Mn, Ni, Ba, Cr, Cu, B, or Sn.A process for producing pyrolysis oil comprises the following steps: A) First, a feedstock to be treated is fed into a pyrolysis zone of a reactor and pyrolyzed there at a temperature of 250 to 700 °C (material temperature measured at the inner surface of the reactor wall of the pyrolysis reactor), wherein the residence time of the material to be pyrolyzed in the pyrolysis zone is 1 second to 1 hour. The material obtained at the end of the pyrolysis zone is referred to as “pyrolyzed material.” The pyrolyzed material comprises pyrolyzed solids and pyrolysis vapors.B) Finally, the pyrolysis oil is optionally separated from other pyrolysis products formed in a separation unit. In particular, the pyrolysis oil can be separated from an aqueous phase that is also formed.Preferably, the at least one impurity of the hydrocarbon-comprising compound comprises at least one halogen-comprising component. The halogen-comprising component preferably comprises a chlorine-comprising component and / or a bromine-comprising component.Preferably, the at least one impurity comprises at least one phosphorus-comprising component.Preferably, in the method according to the present invention, the impurities Cl, Br, and P are reduced. More preferably, the hydrocarbon-comprising composition comprises, after the contact step, less than 100 ppm Cl, less than 200 ppm Br, and / or less than 10 ppm P.Preferably, the contact step is carried out at a temperature in the range of 350 to 1000 °C, more preferably 500 to 700 °C, even more preferably 550 to 650 °C, and most preferably 575 to 625 °C. It is also preferred that the contact step be carried out at a pressure in the range of 0.1 to 150 bar, particularly preferred 0.5 to 1.5 bar.In a preferred embodiment of the present invention, the residence time of the hydrocarbon-comprising composition on the pyrolysis coke in the contact step is 0.1 s to 60 min, preferably 0.5 s to 60 s, more preferably 1 s to 45 s, even more preferably 2.5 to 30 s, and particularly preferably 3.0 s to 20 s.When the contact step is carried out continuously, the weight-based space velocity (WHSV) is preferably in the range of 0.01 to 50 1 / h, more preferably in the range of 0.1 to 15 1 / h, even more preferably in the range of 0.5 to 10 1 / h, and particularly preferably in the range of 0.9 to 6.0 1 / h.In a particularly preferred embodiment of the present invention, the process is carried out at a temperature in the range of 500 to 700 °C and at a residence time of 0.5 s to 45 s, preferably at a temperature in the range of 550 to 650 °C and a residence time of 2.5 s to 30 s, particularly preferably at a temperature in the range of 575 to 625 °C and a residence time of 3 s to 20 s, and most preferably at a temperature in the range of 595 to 605 °C and a residence time of 4.0 s to 6.0 s.In a further particularly preferred embodiment of the present invention, the process is carried out at a temperature in the range of 500 to 700 °C and at a weight-based space velocity (WHSV) of 0.1 to 15 1 / h, preferably at a temperature in the range of 550 to 650 °C and at a weight-based space velocity (WHSV) of 0.5 to 10 1 / h; particularly preferably at a temperature in the range of 575 to 6250 °C and at a weight-based space velocity (WHSV) of 0.9 to 6.0 1 / h, and most particularly preferred at a temperature in the range of 595 to 605 °C and at a weight-based space velocity (WHSV) of 3.0 to 4.0 1 / h.Preferably, the process is carried out continuously. It is particularly preferred that the pyrolysis coke be continuously fed in the pyrolysis coke supply step.In another particularly preferred embodiment of the present invention, the pyrolysis coke is moved in the contact step relative to the direction of movement of the hydrocarbon-comprising composition, preferably in the opposite direction and / or transversely to the direction of movement of the hydrocarbon-comprising composition.In particular, when the contact step is carried out continuously, the residence time is also influenced by the maximum filling level of the reactor. Typically, in order to exploit the activity of the pyrolysis coke to the greatest extent possible, the highest possible filling level is achieved (a filling level of at least 50% is likely to be appropriate). In continuous operation, once the desired fill level has been reached, spent pyrolysis coke is discharged from the reforming zone to the extent that pyrolysis coke is fed into the reforming zone. To enable the most efficient possible contact of the hydrocarbon-comprising composition, according to a further preferred embodiment, the hydrocarbon-comprising composition is fed to the contact step such that the volume flow of the hydrocarbon-comprising composition is guided substantially entirely through flow paths present in the pyrolysis coke bed. The reactor of the contact step is therefore preferably designed such that the hydrocarbon-comprising composition must not only flow over the pyrolysis coke bed but also completely penetrate it. It is particularly preferred that the pyrolysis coke bed be arranged in the contact stage reactor such that a cross-sectional area of the contact stage reactor arranged perpendicular to the flow direction is essentially completely filled with the pyrolysis coke bed. Accordingly, the residence times of the hydrocarbon-comprising composition in the contact stage reactor specified above are also based on such complete filling. Preferably, the pyrolysis bed comprises no further component in addition to the pyrolysis coke that comprises a catalytically active component, wherein the catalytically active component comprises at least one element, preferably consists of it, and wherein the at least one element is preferably selected from the group consisting of Si, Al, Ca, Fe, Ti, Na, Mg, Zn, Mn, Ni, Ba, Cr, Cu, B, or Sn.In another preferred embodiment, the flow of the hydrocarbon-comprising composition is directed through the pyrolysis coke bed in such a way that the hydrocarbon-comprising composition does not come into contact with the pyrolysis coke that has been in the reactor of the contact stage the longest until the very end of the contact stage. The hydrocarbon-comprising composition is thus first brought into contact with the pyrolysis coke that has just been fed into the reactor of the contact step and should also exhibit the highest activity. Gradually, the hydrocarbon-comprising composition is then brought into contact with pyrolysis coke that is catalytically less and less active, until finally, contact also occurs with pyrolysis coke that is about to be discharged. In a continuous process, the feed of pyrolysis coke to the contact step is preferably also arranged to be continuous.The process of the present invention may comprise further steps. For example, the contact step may be preceded by an evaporation step in which the hydrocarbon-comprising composition is evaporated. Such an embodiment has the advantage that the contact is intensified and the hydrocarbon-comprising composition has a higher temperature, which can lead to a more efficient reaction, i.e., higher aromatic yields and lower impurities.Furthermore, the method of the present invention preferably comprises a washing step in which the pyrolysis coke is washed with an acid, a base, and / or a solvent, preferably an acid and a solvent, before being fed to the contact step. This reduces the formation of initial products with even higher levels of impurities.In addition, the method of the present invention may preferably comprise a separation step following the contact step, in which the pyrolysis coke is separated from the hydrocarbon-comprising composition. Such a separation step is not strictly necessary if the hydrocarbon-comprising compound is brought into contact in the gaseous state. Furthermore, such a separation step is not strictly necessary if the process is carried out continuously.The contact step can be carried out in a reactor. Preferably, the pyrolysis coke can be continuously or discontinuously replaced therein to remove loaded or spent coke and to replenish unloaded or unused coke. This can be implemented as a fixed-bed, moving-bed, or fluidized-bed reactor, or in another form.In a particularly preferred embodiment of the present invention, the pyrolysis coke can be produced directly in a pyrolysis step preceding the contact step. In that case, the starting material is the hydrocarbon-comprising composition.UseAs described above, the present invention relates to the use of a pyrolysis coke for reducing impurities in a hydrocarbon-comprising composition, wherein the pyrolysis coke comprises at least one catalytically active component.The pyrolysis coke comprises a catalytically active component. The catalytically active component preferably comprises at least one element, or preferably consists of said element, wherein the at least one element is selected from the group consisting of Si, Al, Ca, Fe, Ti, Na, Mg, Zn, Mn, Ni, Ba, Cr, Cu, B, or Sn. It is particularly preferred that the at least one element be selected from the group consisting of Si, Al, Ca, Fe, Ti, Zn, Mg, Na, and Ca. It is especially preferred that the at least one element be Ca.Preferably, the catalytically active component comprises 1.0 to 35.0 wt.-%, preferably 15.0 to 30.0 wt.-%, of Ca, 0.1 to 20.0 wt.-%, preferably 5.0 to 15.0 wt.-%, Si, 0.1 to 25.0 wt.-%, preferably 10.0 to 20.0 wt.-%, Al, 0.1 to 10.0 wt.-%, preferably 1.0 to 5.0 wt.-%, Zn, 0.1 to 10.0 wt.-%, preferably 0.5 to 5.0 wt.-%, Fe, 0.1 to 10.0 wt.%, preferably 0.5 to 5.0 wt.%, Cu, 0.1 to 5.0 wt.%, preferably 1.0 to 3.0 wt.%, Ti, and / or 0.01 to 1.5 wt.%, preferably 0.1 to 1.0 wt.% Ba.Preferably, the at least one element in the catalytically active component is present in an activated form, preferably an oxidized form, a reduced form, a sulfured form, a chlorinated form, or a mixture thereof.The catalytically active component is present in the pyrolysis coke preferably in a proportion of 0.1 to 50 wt.%, preferably 0.5 to 20 wt.%, based on the total mass of the pyrolysis coke.Preferably, the pyrolysis coke has a pore volume of more than 0.001 cm2 / g, and more preferably of more than 0.01 cm3 / g, as measured according to DIN ISO 9277-2014-01. Typically, the pore volume of the pyrolysis coke is no higher than 0.1 cm3 / g.Likewise, the pyrolysis coke preferably has a pore size of more than 5 nm, more preferably of more than 8 nm, and particularly preferably of more than 10 nm, measured according to DIN ISO 9277-2014-01. Typically, the pore size of the pyrolysis coke is no greater than 50 nm.The pyrolysis coke also preferably has a specific surface area of more than 1.0 m2 / g, more preferably more than 2 m2 / g, and most preferably more than 4.5 m2 / g, measured according to DIN ISO 9277-2014-01. Typically, the specific surface area of the pyrolysis coke is no greater than 10 m2 / g.Preferably, the hydrocarbon-comprising composition is liquid at 20 °C and 1 bar. More preferably, the hydrocarbon-comprising composition is selected from the list consisting of petrochemical intermediates, waste oil, and pyrolysis oil; most preferably, the hydrocarbon-comprising composition comprises or consists of pyrolysis oil.In a particularly preferred embodiment of the invention, the hydrocarbon-comprising composition comprises 5 to 85 wt.%, preferably 40 to 65 wt.%, carbon, 0.5 to 5 wt.%, preferably 1 to 3.5 wt.%, hydrogen, 0.1 to 3 wt.-%, preferably 0.5 to 1.5 wt.-%, nitrogen, and / or 0.01 to 1 wt.-%, preferably 0.1 to 0.5 wt.-%, sulfur.Preferably, the at least one impurity of the hydrocarbon-comprising compound comprises at least one halogen-comprising component. The halogen-comprising component preferably comprises a chlorine-comprising component and / or a bromine-comprising component.Preferably, the at least one impurity comprises at least one phosphorus-comprising component.Preferably, the use according to the present invention reduces the impurities Cl, Br, and P in the hydrocarbon-comprising composition. More preferably, the hydrocarbon-comprising composition comprises, after use, less than 100 ppm Cl, less than 200 ppm Br, and / or less than 10 ppm P.Experimental SectionMeasurement Methodsa) Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)Liquid samplesICP measurements of liquid samples were performed using a Spectro Arcos ICP-OES in dual-side-on plasma mode. The ICP system was equipped with a Nordermeer nebulizer, a cyclone spray chamber, and a fixed glass torch with a 1.8 mm injector. The measurement conditions were RF power 1350 W, plasma gas flow 14 L / min, nebulizer flow 0.72 L / min, and auxiliary gas flow 2 L / min. The sample flow rate was set to 2.0 mL / min. All samples and standards were diluted 1:10 with 1-butanol. The concentration of Cl was determined according to DIN 51577-5. The concentration of P was determined according to DIN EN 51363-3. The concentrations of other elements were determined according to DIN EN ISO 11885.SolidsThe concentrations of selected elements were determined in accordance with DIN EN ISO 11885 following digestion with aqua regia in accordance with DIN EN ISO 54321 and following fusion digestion in accordance with DIN ISO 14869 for Ba, Ca, Cu, and Fe, or by microwave digestion in accordance with DIN 51460-3 for other selected elements.c) Gas Chromatography with Mass Spectrometry (GC-MS)All GC-MS measurements were performed using a gas chromatograph coupled with a mass spectrometer (GC-MS), model GCMS-QP2020 from Shimadzu Kabushiki Kaisha, Kyoto (Japan).A nonpolar DB-5 column (30 m, 0.2 mm inner diameter, and 0.25 µm film thickness) was used. Helium (purity 5.0) was used as the carrier gas for all measurements. The injection volume was 1 µl for a dilution of 1 mg of sample in 1 ml of dichloromethane (DCM). The measurements were performed at a carrier gas flow rate of 40 mL / min. After a hold time of 3 min at 40 °C, the GC oven temperature was set to 320 °C (3-min hold time) with a constant heating rate of 10 K / min. The injector temperature was set to 250 °C, the MS surface to 280 °C, and the MS to 200 °C. The quadrupole MS detector was operated at a scan rate of 5000 Hz and in a mass range of 35–500 m / z, and the solvent cut-off time was 3 minutes.The NIST 17 database was used to identify the substances. Since the chromatogram showed peaks, the area of each peak was directly linked to the percentage composition. First, each value was normalized, i.e., scaled to the sum of the areas of the peaks that appear among the 100 largest peaks. By comparing the mass spectra with the NIST 17 database, substances with a similarity index (SI) > 70 are identified. An SI of 100 corresponds to an exact match between the mass spectra from the measurement and those in the NIST 17 database.The values for the GC / MS measurements are given as area % (area %) of the areas integrated under the peaks.d) Elemental AnalysisThe determination of the CHNS composition was performed using a vario macro cube from Elementar. The measurements were carried out based on DIN 51724-3 for S and DIN 51732 for C, H, and N using triplicate determinations.e) Specific surface area, pore size, pore volumeThe specific surface area, pore size, and pore volume were determined in accordance with DIN ISO 9277-2014-01 – “Bestimmung der spezifischenOberfläche von FestkörpernmittelsGasadsorption - BET-Verfahren“ (“Determination of the specific surface area of solids by gas adsorption – BET method.”)f) Mass-based space velocityThe mass-based space velocity WHSV is calculated using Equation (1):(1)whereWHSV is the mass-specific space velocity in 1 / h,Mfeed is the mass flow rate of the pyrolysis oil used (plus, if applicable, the nitrogen mass flow rate) in kg / h, andmcat is the mass of the pyrolysis coke in kg.The mass of the pyrolysis coke can be determined by weighing before the pyrolysis coke is fed into the reactor. The mass flow rate mcat can also be measured or adjusted. Alternatively, the mass flow rate mcat can be calculated from the oil flow rate using the measured density of the oil (often in the range of 0.9 kg / m3).g) Residence timeThe residence time is calculated according to Equation (2):(2)wheret is the residence time in s,Vtube is the pipe volume of the coke bed in m3, andWgas is the volume flow rate of the vaporized pyrolysis oil in m3 / s.Examplesa) Pyrolysis (IE1-3)Experimental SetupThe pyrolysis of the starting materials to produce pyrolysis coke was carried out in a system as shown in Figures 1 and 2. For the pressure test, a pressure sensor was connected to the ALMEMO 710 precision measuring device. The compressed air hose was connected to a valve and inserted into the collection vessel. The valve was opened for a brief interval and then closed again. If the pressure drop in the system was less than 1 mbar per second, the pressure test was considered successful. After completion of the pressure test, the shut-off valve was replaced with a three-way valve.To purge the system with nitrogen, a nitrogen hose was connected to the collection vessel and a flow rate of 0.5 L / min was set. The three-way valve was rotated so that gases escaping from the reactor could pass through the activated carbon filter. The lambda probe reading was checked to ensure that the oxygen content in the system had dropped to 0% by volume as a result of the nitrogen purge.To heat the reactor, all temperature sensors were connected to the ALMEMO 710 precision measuring instrument. The temperature controller was then turned on to heat the reactor to 520 °C.During heating, the freshly filled wash bottles were connected with plastic tubing between the three-way valve behind the coolers and the gas analyzer. The cooling units were then filled with ice or water, depending on the feedstock. After the gas analyzer was connected to the system, it was turned on and was ready for operation after 5-7 minutes.For pyrolysis, the starting material was weighed and loaded into the lance. After loading, the ball valve was closed, and the lance was mounted onto the reactor’s shut-off valve via the screw cap. Additionally, the nitrogen supply was connected to the lance, and a flow rate of approximately 0.5 L / min was set.Once a stable reactor temperature was reached, recording was started for the gas analyzer and ALMEMO 710. The three-way valve was opened so that all resulting gases were directed to the wash bottle. By opening the ball valve on the lance and the reactor, the starting material entered the reactor due to the slope. The filling rod on the lance was pressed in, causing the material to be conveyed into the reactor. The reactor’s shut-off valve was closed. After loading, the energy was absorbed by the introduced material as a result of the thermochemical process, leading to a drop in temperature, and the heat supply was increased via the temperature controller to maintain a stable temperature.The filling lance was then purged with nitrogen, disassembled, and refilled with the new batch. The filling lance was then reassembled and purged with nitrogen again for approximately five minutes. After a residence time of 15 minutes following the last material addition, the next addition process was initiated.After the holding time for the last batch had elapsed, the reactor was emptied for the final time and the reactor heating was turned off. Recording of the measured values continued for about 10 to 15 minutes to capture any subsequent changes in temperature, pressure, or gas composition. Heat supply to the transition pipe and the tar filter was also maintained during this period to prevent further clogging of these components.Test ProcedureThe following feedstocks were converted to pyrolysis coke via pyrolysis:MPO323 (IE1) Mixed polyolefin fraction from the dual system in Germany (Der Grüne Punkt – Duales System Deutschland GmbH). The MPO with fraction number 323 was used, which means it primarily comprises polypropylene (PP) and polyethylene (PE). PP and PE are used, for example, in cups, films, and other household items; secondary components such as labels may also be present. The MPO323 fraction is currently not recycled and is incinerated for energy recovery. The fraction numbers are part of Germany’s dual system, which uses these numbers to define mixed plastic waste. Further information on this mixed polyolefin fraction can be found in Raw Material Fraction Specification 323-2 Flexible PO Articles, version dated April 5, 2023, available at https: / / www.gruener-punkt.de / fileadmin / Files / Downloads / PDFs / Raw Material Fraction Specifications 2023 / DOC-23-50738_-_Raw Material Fraction Specification_323-2_Flexible_PO_Articles_-_v0.02.0006.pdf.MK350 (IE2) This is a fraction of mixed plastics (polyethylene, polypropylene, polystyrene, polyethylene terephthalate) from the dual system in Germany (Der Grüne Punkt – Duales System Deutschland GmbH). Further information on this mixed plastic fraction can be found in the Raw Material Fraction Specification 350 Mixed Plastics dated April 5, 2023, available at https: / / www.gruener-punkt.de / fileadmin / Files / Downloads / PDFs / RawMaterialFractionSpecifications2023 / DOC-23-50749_-_RawMaterialFractionSpecification_350_MixedPlastics_-_v0.02.0006.pdf.WEEE (IE3) Shredded waste electrical and electronic equipmentPC (CE2) Untreated polycarbonate granules from SABIC are commercially available.ResultsThe pyrolysis cokes MPO323 (IE1) and MK350 (IE2) obtained were analyzed for their elemental content. The results are listed in Table 1.Table 1: Elemental composition of the pyrolysis cokes in [mg / kg] measured by ICP-OES. * digested with aqua regia / # fusion digestion BaCaCu FeMPO323*7300> 120,00021,00018,000MK350#6600210,0009,00017,000MPO323*7,700> 120,00029,00024,000MK350#6,700220,00017,00017,000 Ag AlAs AuMPO32310110,000< 10< 10MK35010180,000< 10< 10 BBBiCdMPO323200< 10< 10< 10MK350200< 10< 10< 10 CeCoCrDyMPO3231030600< 10MK3501020600< 10 HeEUGaGdMPO323< 10< 10< 20< 10MK350< 10< 10< 20< 10 Ge Hf Hg Ho MPO323< 10< 10< 10< 10MK350< 10< 10< 10< 10 In IrK La MPO323< 10606,700< 10MK350< 10905,800< 10 Li Lu Mg MnMPO32320< 1012,000500MK35010< 1012,000600 MonNa Nb Nd MPO323< 1016,000< 10< 10MK350< 1017,000< 10< 10 Ni P PbPd MPO3236003,400500< 10MK3506003,100800< 10 PrPtRh Ru MPO323< 10< 10< 10< 50MK350< 10< 10< 10< 50 S SbScSe MPO3236,700100< 1030MK3505,900100< 1050 SiSm Sn Sr MPO32383,000< 10200300MK35084,000< 10200300 Ta Tb Te Th MPO323< 10< 10< 10< 10MK350< 10< 10< 10< 10 Ti Tl Tm U MPO32331,000< 10< 10< 100MK35036,000< 10< 10< 100 VWYYbMPO32320< 10< 10< 20MK35020< 10< 10< 20 ZnZr   MPO32327,00060  MK35034,00050   Table 2: Comparison of pyrolysis coke. 1Values were measured using ICP-OES (solid sample) as described herein and converted to the oxide form.2 Fuel Processing Technology 182 (2018) 26–36  MPO323 (IE1)1MK350 (IE2)1Biochar2E-Waste Char2Fe / Biochar2SiO2[wt.%]6.97.310.880.67633.3Al2O3[wt.%]9.29.31.280.1655.46CaO[wt.%]21.723.01.281.895.13Fe2O3[wt.%]1.52.21.121.2117.2TiO2[wt.%]2.32.50.0600.24Na2O[wt.%]0.90.930.820.113.33ZnO[wt.%]1.31.8---MgO[wt.%]0.730.80.480.422.03Others[wt.%]  84.0895.5333.31BET[m2 / g]6.15.34.24.552.4Pore volume[cm2 / g]0.0160.0130.0080.0060.055Pore size[nm]10.610.27.655.434.2 Table 3: Elemental analysis of N, C, H, S as described herein for the pyrolysis coke (IE1) produced from MPO323 NCHSMPO323 Coke (IE1)0.6763.663.140.14MPO323 Coke (IE1)1.2141.531.500.30 h) Reduction of impurities in pyrolysis oil using pyrolysis coke (CE3-4; IE4-7)Experimental setupFigure 1 shows the experimental setup for the process used to reduce impurities in pyrolysis oil. A quartz glass cylinder with an inner diameter of 16 mm was used as the reactor. The coke bed was located in the center of the glass reactor and was held in place by glass wool. The upper part of the reactor was sealed with a PTFE rubber septum, through which the nitrogen supply and the 0.8-mm-diameter cannula for feeding the pyrolysis oil were routed. The pyrolysis oil was fed via a feed oil pump, which generated a constant oil flow at the desired flow rate. A tubular heating element was arranged around the reactor, and a thermocouple was installed in the center of the reactor’s heating zone for temperature control. Cooling unit 1 was located directly below the reactor. The beaker was connected to cooling unit 1. Cooling unit 2, comprising glass wool, was connected to the beaker to achieve a higher liquid yield. To achieve optimal cooling performance, the water flowed in the opposite direction to the gas. The resulting product was collected in a beaker. The excess gas was allowed to escape from cooling unit 2. To achieve maximum oil yield, the beaker was cooled in an ice-water bath.Experimental Procedure5 g of coke was weighed and placed in the center of the glass reactor, with the coke bed held in place by glass wool at a height of 50 mm. The weight of the reactor was determined before and after filling. Subsequently, a 24-ml syringe with a 0.8-mm needle was filled with oil. An oil sample was taken from the syringe to determine the exact composition of the oil used for analysis. The syringe was then clamped into the pump, and the needle was inserted through the membrane into the reactor. Before the experiment began, the entire system was purged of air by flushing with nitrogen (200 ml / min) for at least 3 minutes. Once the inert gas had distributed throughout the system and the air had been displaced, the nitrogen flow was set to 50 ml / min. The heater was then turned on and the reactor heated to the desired temperature. Thermocouples were used to monitor the temperature inside the reactor. As soon as the system reached the desired temperature of 600 °C, the syringe pump was turned on, delivering a constant flow rate of 0.25 ml / min of oil. The oil was converted into a gaseous phase in the reactor and flowed through the coke bed. The gas condensed in the condenser, and the liquid product was collected in the beaker. The mass flow rate of the pyrolysis oil was determined by weighing the syringe before and after the experiment and calculating the duration of the experiment. A WHSV of 3.63 1 / h was determined.The following coke materials were examined. CE3 is untreated pyrolysis oil. In this case, therefore, no reaction took place on a coke. In CE4, a coke similar to that used in CE2 was employed, i.e., a pyrolysis coke based on pure polycarbonate. This pyrolysis coke comprises no catalytically active components and therefore serves as a control sample. In the following examples IE4-6, increasingly larger amounts of coke produced as in IE1 - i.e., MPO323-based coke - were successively mixed with CE2, i.e., pure polycarbonate-based coke. IE7 then examines a coke bed consisting exclusively of coke produced as in IE1. These experiments allow not only the absolute influence of a pyrolysis coke on the composition of the oil to be purified to be assessed, but also the relative influence in combination with a pyrolysis coke that comprises no catalytically active components.ResultsTable 4 shows the proportions of aromatic, monocyclic aromatic, and aliphatic hydrocarbons in the pyrolysis oils obtained from experiments CE3-4 and IE4-7. The proportions of Alip and Total add up to 100%, while the proportions of Mono and PAH correspond to the Total proportions. It can be observed that the enrichment of aromatic hydrocarbons is generally enhanced by the presence of a coke bed. The method according to the invention does not yield inferior results but is capable of slightly increasing the aromatic fractions even further.Table 4: Fractions of aromatic compounds in the pyrolysis oil measured by GC / MS as described herein. aBenzene, toluene, ethylbenzene, xylene; bBTEX + styrene; cMonocyclic aromatics; dPolycyclicaromatic hydrocarbons; eAliphatic compounds; f Aromatic compounds CokeBTEXaBTEXSbMonocPAHdAlipeTotalfCE3-38.7451.3758.960.0041.0558.96CE4CE252.0869.6077.550.7721.6878.32IE475:25 CE2:IE157.9972.1581.274.7014.0385.97IE550:50 CE2:IE164.0080.0789.050.0010.9489.05IE625:75 CE2:IE162.2877.2986.190.3713.4186.56IE7IE166.1977.0184.624.7110.6789.32Table 5 lists the measured impurities in the pyrolysis oils from experiments CE3-4 and IE4-7. It shows that halogens such as Cl or Br were significantly reduced in the case of pure MPO. However, an effect can already be achieved even with a proportion of coke according to the invention.Table 5: Proportion of impurities in the pyrolysis oil in [ppm] measured by ICP-OES (liquid sample). CokeClSAlPBrCE3-42,8877881.2232.27195.33CE4CE235,9206950.5221.05136.00IE475:25 CE2:IE121,847----IE550:50 CE2:IE130,827----IE625:75 CE2:IE124,490----IE7IE16836790.023.151.10 i) Reduction of impurities in pyrolysis oil using pyrolysis coke from various sources (CE4, IE7, IE8)Experimental setupThe same experimental setup as in examples CE3-4 and IE4-7 was used.Experimental ProcedureThe same experimental procedure as in examples CE3-4 and IE4-7 was used. However, in addition to the cokes produced as in CE1 (CE4) and IE1 (IE7), a coke produced as in IE3 was also compared (IE8).ResultsTable 6 shows the fractions of aromatic, monocyclic aromatic, and aliphatic hydrocarbons in the pyrolysis oils obtained from experiments CE3, CE4, IE8, and IE7. The fractions of Alip and Total add up to 100%, while the fractions of Mono and PAH correspond to the Total fraction. It can be observed that the enrichment of aromatic hydrocarbons is generally enhanced by the presence of a coke bed. It turns out that the MPO323-based coke bed (IE1 and IE7) performs better than the WEEE-based coke bed (IE3 and IE8). Table 6: Fractions of aromatic compounds in pyrolysis oil for various pyrolysis cokes measured by GC / MS as described herein. aBenzene, toluene, ethylbenzene, xylene; bBTEX + styrene; cMonocyclic aromatics; dPolycyclicaromatic hydrocarbons; eAliphatic compounds; fAromatic compounds CokeBTEXaBTEXSbMonocPAHdAlipeTotalfCE3-38.7751.3758.960.0041.0558.96CE4CE252.0869.60577.550.7721.6878.32IE8IE355.8573.8082.802.5514.6785.34IE7IE166.1977.0184.624.7110.6789.32Table 7 lists the measured impurities in the pyrolysis oils from tests CE3-4 and IE7-8. It can be seen that halogens such as Cl or Br were significantly reduced in the case of pure MPO. It also turns out here that the MPO323-based coke bed (IE1 and IE7) performs better than the WEEE-based coke bed (IE3 and IE8).Table 7: Proportion of contaminants in the pyrolysis oil for various pyrolysis cokes in [ppm], measured by ICP-OES (liquid samples) as described herein. CokeClAlPCE3-42,8871.2232.27CE4CE235,9200.5221.05IE8IE331,9930.3124.00IE7IE16830.023.15j) Results dependent on temperature and flow rate (IE7, IE9-12)Experimental setupThe same experimental setup as in examples CE3-4 and IE4-8 was used.Experimental procedureThe same experimental procedure as in examples CE3-4 and IE4-8 was used. However, in examples IE9-12, different temperatures and flow rates were used than in IE7 (600 °C; 0.25 ml / min) (see Tables 8 and 9). ResultsTable 8: Experiments as a function of temperature and flow rate (or WHSV or residence time), Cl impurities in the pyrolysis oil in [ppm] measured by ICP-OES (liquid sample); proportions of aromatic compounds in the pyrolysis oil measured by GC / MS as described herein. aPolycyclic aromatic hydrocarbons, bAromatic compounds TFlow rateWHSVResidence timeClaPAHbTotal [°C][ml / min][1(h][s][ppm][Fl.-%][Vol. %]IE95000.050.9716.771410.0064.58IE76000.253.634.466834.7189.32IE107000.456.302.57491911.2799.50 Table 9: Experiments as a function of temperature and flow rate (or WHSV or residence time), Cl impurities in the pyrolysis oil in [ppm] measured by ICP-OES (liquid sample); proportions of aromatic compounds in the pyrolysis oil measured by GC / MS as described herein. aPolycyclic aromatic hydrocarbons, bAromatic compounds TFlow rateWHSVResidence timeClaPAHbTotal [°C][ml / min][1(h][s][ppm][v / v][vol.%]IE115000.456.302.5727420.0060.95IE76000.253.634.466834.7189.32IE127000.050.9716.7779525.7599.80 The examples in Tables 8 and 9 show that short residence times lead to a reduced reduction of impurities. Without wishing to be bound by any theory, it is assumed that the shorter residence times also allow for shorter desorption or adsorption on the pyrolysis coke. It can be seen that, relatively speaking, higher temperatures at the same residence times also lead to higher impurity levels in the product (see IE9 vs. IE12). An analysis of the impurities indicates that lower temperatures and longer residence times represent an optimum (see IE9).However, in addition to impurities, the effect on the yield and quality of aromatics must not be overlooked. Tables 8 and 9 show that the total amount of aromatics increases significantly with temperature. The decrease with decreasing residence time appears to be negligible. In this respect, a contrasting picture emerges. While IE9 is the optimum for impurities, IE12 is the optimum for aromatic yields. However, the yield of polycyclic aromatics also increases with rising temperature. Since these are less desirable, it becomes apparent that selecting a temperature of 600 °C and a residence time of 4.46 s (without nitrogen flow) or a WHSV of 3.63 1 / h represents an optimum in terms of reducing impurities, maximizing the yield of aromatics, and maximizing the quality of these aromatics. 

Claims

1. A method for reducing at least one impurity in a hydrocarbon-comprising composition, the method comprising the following steps:providing, in a composition provision step, a hydrocarbon-comprising composition;providing, in a pyrolysis coke provision step, a pyrolysis coke, wherein the pyrolysis coke comprises at least one catalytically active component;in a contact step, contacting the pyrolysis coke with the hydrocarbon-comprising composition.

2. The method according to claim 1, wherein the contact step is carried out at a temperature in the range of 350 to 1000 °C, preferably 500 to 700 °C.

3. The method according to claim 1 or 2, wherein the contact step is carried out at a pressure in the range of 0.1 to 150 bar, preferably 0.5 to 1.5 bar.

4. The method according to any one of the preceding claims, wherein the residence time of the hydrocarbon-comprising composition on the pyrolysis coke in the contact step is from 0.1 s to 60 min, preferably from 0.5 s to 60 s.

5. The method according to any one of the preceding claims, wherein the contact step is carried out continuously and the weight-based space velocity (WHSV) is in the range of 0.1 to 30 1 / h, preferably in the range of 0.25 to 15 1 / h.

6. The method according to one of the preceding claims, wherein the pyrolysis coke is moved in the contact step relative to the direction of movement of the hydrocarbon-comprising composition, preferably in the opposite direction and / or transversely to the direction of movement of the hydrocarbon-comprising composition.

7. Use of a pyrolysis coke for reducing at least one impurity in a hydrocarbon-comprising composition, wherein the pyrolysis coke comprises at least one catalytically active component. 8. The method according to any one of the preceding claims 1 to 6, or a use according to claim 7, wherein the catalytically active component comprises at least one element, preferably consists of said element, wherein said at least one element is selected from the group consisting of Si, Al, Ca, Fe, Ti, Na, Mg, Zn, Mn, Ni, Ba, Cr, Cu, B, or Sn, is preferably selected from the group consisting of Si, Al, Ca, Fe, Ti, Zn, Mg, Na, and Ca, and most preferably is Ca.

9. The method according to any one of the preceding claims 1 to 6, or the use according to claims 7 or 8, wherein the element is present in an activated form.

10. The method or use according to claim 9, wherein the element is present in an oxidized form, a reduced form, a sulfured form, a chlorinated form, or mixtures thereof.

11. The method according to any one of the preceding claims 1 to 6, or the use according to any one of the preceding claims 7 to 10, wherein the pyrolysis coke may be produced by pyrolysis of a starting material.

12. The method or use according to claim 11, wherein the starting material comprises a mixture of polymers.

13. The method or use according to claim 12, wherein the polymers are selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), polyvinyl chloride (PVC), polyamide (PA), and polyethylene terephthalate (PET).

14. The method according to any one of the preceding claims 1 to 6 or the use according to any one of the preceding claims 7 to 13, wherein the impurity comprises at least one halogen-comprising component, preferably consists of it.

15. The method according to any one of the preceding claims 1 to 6, or the use according to any one of the preceding claims 7 to 14, wherein the impurity comprises at least one phosphorus-comprising component, preferably consists of such a component. 

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