Pyrolysis oil and / or fossil naphtha as indirect gasification feedstock

Abstract

A process for the production of olefins by indirect gasification, wherein the process comprises the steps of feeding a feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes to a fluidized bed gasifier; feeding a steam stream to the fluidized bed gasifier; and gasifying the feedstock in the fluidized bed gasifier; wherein the step of gasifying the feedstock in the fluidized bed gasifier is carried out at a temperature in the range of 600 DEG C to 900 DEG C. Use of a feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes for the production of olefins.

Description

Technical Field

[0001] The present invention relates to the field of polymer recycling and in particular to the recycling of pyrolysis products obtained from plastic waste. Even more particularly, the invention relates to the conversion of such pyrolysis products into olefins by indirect gasification. Background Art

[0002] Current chemical recycling processes are often limited in terms of feedstock specifications or product value. Commercial-scale pyrolysis processes are under development, but to date, these have required strict specification of the waste feedstock composition. This limits the availability of feed streams. The resulting fractionation also means that the remaining components lose value, making it increasingly difficult to increase the circularity of the overall material system.

[0003] EP 3 950 889 A1 mentions the option of combining plastic waste with hydrocarbon feedstocks in catalytic cracking. However, the catalytic nature of the process dictates strict feed specifications.

[0004] GB 2 601 570 A discloses a method for obtaining solid recovered fuel from waste-based feedstock and converting it into synthesis gas, which, after purification, can serve as feedstock for downstream processes such as Fischer-Tropsch synthesis, ammonia synthesis or methanol synthesis.

[0005] WO 2021 / 105327 A1 relates to a method for producing high-quality components, particularly hydrocarbons, from liquefied waste plastics, and involves co-feeding a highly paraffinic material and (preferably pretreated) liquefied waste plastics into a steam cracking process. However, a disadvantage of this process is its low tolerance for impurities (particularly chlorine and olefinic compounds) in the mixed feedstock.

[0006] The partial oxidation gasification process is capable of accepting lower quality feeds but is primarily used to produce synthesis gas, which requires further processing and energy to convert to hydrocarbons for recycling.

[0007] Mandviwala et al.'s "Biomass Conversion and Biorefinery" (https: / / doi.org / 10.1007 / s13399-022-02925-z, published online June 14, 2022) outlines the thermochemical conversion of biomass feedstocks, specifically rapeseed oil, into building blocks for the chemical industry as a means of introducing fossil-free feedstocks. While this idea could reduce the global environmental impact of polymer production, it does nothing to address the accumulation of plastic waste unless the plastics are incinerated to form CO2 or recycled in some way.

[0008] Furthermore, according to Kusenberg et al., "Waste Management," Vol. 148, pp. 83-115 (2022), typical steam cracking feedstocks used for base chemical production can tolerate only small amounts of contaminants. Specifically, a typical steam cracking feedstock may contain no more than 3 ppm of chlorine, 100 ppm of nitrogen, and 100 ppm of oxygen. Summary of the Invention

[0009] Purpose of the Invention

[0010] The present invention aims to provide a one-step conversion process for producing olefins from a feedstock containing fluid aliphatic hydrocarbons and / or cycloalkanes (e.g., pyrolysis products and / or fossil naphtha) without the need for hydrotreating the feedstock prior to gasification. Consequently, the present invention aims to provide a process with a higher tolerance to contaminants, particularly chlorine. SUMMARY OF THE INVENTION

[0012] Surprisingly, it has been found that the above object can be achieved by a method for producing olefins by indirect gasification, wherein the method comprises the following steps: feeding a feedstock containing fluid aliphatic hydrocarbons and / or cycloalkanes to a fluidized bed gasifier; feeding a steam stream to the fluidized bed gasifier; and gasifying the feedstock in the fluidized bed gasifier; wherein the step of gasifying the feedstock in the fluidized bed gasifier is carried out at a temperature in the range of 600° C. to 900° C. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of the experimental setup used in industrial-scale experiments; DETAILED DESCRIPTION Detailed Description of the Invention

[0015] The present invention relates to a gasification process suitable for converting plastic waste into olefins.

[0016] As noted above, Mandviwala et al. disclose a method for producing methane from biomass. However, further development of the process now allows for the processing of a wider range of feedstocks and products. The technology has demonstrated good yields of ethylene and propylene when using various aliphatic materials as feedstocks.

[0017] Unlike partial oxidation gasification, the indirect gasification process lacks atmospheric oxygen in the gasifier, creating a chemical environment very similar to conventional hydrocarbon steam cracking. This is achieved by transferring the solid bed material to a separate vessel for heat recovery and incineration of heavy by-products. For example, indirect gasification of polyethylene produces ethylene and propylene comparable to steam cracking of virgin naphtha, demonstrating the commercial potential of the process. However, due to the different CH 4 ratios of the virgin naphtha and polyethylene, the heavy end of the product distribution between indirect gasification and conventional steam cracking exhibits significant differences.

[0018] In the context of the present invention, the expression "indirect gasification" refers to a process in which the heat required for the endothermic conversion of the feedstock is generated outside the chamber in which this conversion takes place.

[0019] It has now been discovered that the developed gasification process (Mandviwala et al.) can also accept liquid oil feedstocks, such as fossil naphtha and pyrolysis oil, resulting in ethylene and propylene yields comparable to those of industrial steam cracking. The gasification process is robust and can accept very low-quality feedstocks, and pyrolysis oil can be fed without any pretreatment steps, making it possible to skip the complex and expensive upgrading of pyrolysis oil.

[0020] Experimental results show that when processed by indirect gasification, heteroatoms tend to leave the carbon matrix and form smaller molecular compounds. Therefore, they can be removed by simpler methods than hydrotreating, such as adsorption, filtration, or even other separation methods. The presence of olefins in the pyrolysis oil does not cause a problem because, unlike traditional steam cracking, the solid bed material in indirect gasification is continuously regenerated, thus preventing coke accumulation by design and thus avoiding plant downtime due to decoking. In addition, contaminants that remain solid under process conditions (such as certain metals) will be captured in the solid stream and can therefore be removed by solid purification.

[0021] Indirect gasification provides conditions for high-temperature pyrolysis while limiting the formation of carbon oxides. Rather than providing heat by directly oxidizing a portion of the feedstock, heat is added to the process by means of a heated solid medium transferred between the reactor and the regenerator.

[0022] The type of solid medium is not particularly limited. Thus, the solid medium may be chemically inert or catalytically active. However, it is required that the solid medium be thermally stable at the operating temperature of the process according to the invention. Alternatively, the expression "solid bed material" may be used to describe the "solid medium."

[0023] raw material

[0024] Typically, the feedstock used in the process of the present invention comprises aliphatic hydrocarbons and / or cycloalkanes, preferably in an amount of at least 50 wt. %, based on the total feedstock.

[0025] Typically, the feedstock comprising aliphatic hydrocarbons and / or cycloparaffins comprises hydrocarbons having greater than 4 carbon atoms.

[0026] Preferably, the feedstock comprising aliphatic hydrocarbons and / or cycloparaffins comprises at least 30 wt.% fluid hydrocarbons, more preferably at least 30 wt.% liquid hydrocarbons.

[0027] In the context of this application, the expression "fluid hydrocarbons" refers to hydrocarbons that are in liquid or gaseous state at ambient temperature and pressure (298 K, 1013 hPa). Similarly, the expression "liquid hydrocarbons" refers to hydrocarbons that are in liquid state at ambient temperature and pressure (298 K; 1013 hPa).

[0028] Preferably, the liquid hydrocarbons contained in the feedstock have a dynamic viscosity in the range of 0.1 mPa·s to 100 mPa·s and a viscosity of about 1 g / ml (1000 kg / m 3 ) density.

[0029] Preferably, the liquid hydrocarbons contained in the feedstock have a density in the range of 0.6 to 1.3 g / ml at ambient temperature.

[0030] Preferably, the feedstock comprises pyrolysis products, such as pyrolysis oils and gases. More preferably, the pyrolysis products are obtained from plastic waste, such as post-consumer waste plastics / recycled consumer plastics. Another way of describing the above is "liquefied waste plastics."

[0031] In particular, it is preferred that the feedstock comprises one or more fluid pyrolysis products, more preferably one or more fluid pyrolysis products obtained from plastic waste, and more preferably one or more fluid pyrolysis products obtained from plastic waste that has not undergone hydrogenation.

[0032] In the context of the present invention, the term "pyrolysis oil" is understood to mean any oil that is at least partly derived from the pyrolysis of plastic waste, including (i) any crude pyrolysis oil derived entirely from the pyrolysis of plastic waste (referred to herein as "plastic waste pyrolysis oil"), (ii) any crude pyrolysis oil derived from the pyrolysis of a mixture of plastic waste and biomass, or (iii) any crude pyrolysis oil comprising a mixture of crude plastic waste pyrolysis oil and crude biomass pyrolysis oil.

[0033] As used herein, "(crude) plastic waste pyrolysis oil" refers to pyrolysis oil produced by pyrolysis of feedstock consisting of plastic waste.

[0034] The term "pyrolysis" includes slow pyrolysis, fast pyrolysis, flash catalysis, and catalytic pyrolysis. These types of pyrolysis differ in terms of process temperature, heating rate, residence time, feed particle size, etc., which leads to different product qualities. Sharuddin et al., "A review of pyrolysis of plastic waste", Energy Conversion and Management, Vol. 115, pp. 308-326 (May 2016), describe typical process conditions for the pyrolysis of plastic waste.

[0035] Typically, plastic waste is a mixture of different plastic materials, including hydrocarbon plastics such as polyethylene (HDPE, LDPE) and polyolefins such as polypropylene, polystyrene, and their copolymers, as well as polymers composed of carbon, hydrogen, and other elements such as chlorine, fluorine, oxygen, nitrogen, sulfur, and silicon. Examples include chlorinated plastics (e.g., polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), etc.), nitrogen-containing plastics (e.g., polyamide (PA), polyurethane (PU), acrylonitrile-butadiene-styrene (ABS), etc.), oxygen-containing plastics (e.g., polyesters (e.g., polyethylene terephthalate (PET), polycarbonate (PC), etc.), silicones, and / or sulfur-crosslinked rubbers. PET plastic waste is typically sorted prior to pyrolysis because PET has a significant resale value. Therefore, the plastic waste to be pyrolyzed typically contains less than about 10 wt.% PET, preferably less than about 5 wt.% PET, based on the dry weight of the plastic material, and most preferably is substantially free of PET.

[0036] The one or more pyrolysis products may be in fluid form, preferably in liquid form (at ambient temperature and pressure; 298K, 1013hPa). Liquid pyrolysis products may also be referred to as pyrolysis oil (see above); gaseous pyrolysis products may also be referred to as pyrolysis gas.

[0037] Optionally, the one or more pyrolysis products may be subjected to a pretreatment operation, for example as described in WO 2020 / 242912 A1; WO 2020 / 242916 A1; WO 2020 / 242925 A1 and WO 2021 / 105327 A1.

[0038] However, the one or more pyrolysis products contained in the feedstock can be used without undergoing hydrotreatment; that is, without the presence of hydrogen and / or hydrogenation catalyst in any optional pretreatment step. In other words, the one or more pyrolysis products are not hydrogenated and / or hydrocracked prior to use as a feedstock in the process as detailed herein.

[0039] Preferably, the feedstock comprising aliphatic hydrocarbons and / or cycloalkanes may comprise, more preferably consist of, one or more pyrolysis products as defined above.

[0040] The raw material is further preferably characterized by having at least one of the following:

[0041] -Chlorine levels of 10 ppm or higher,

[0042] - Nitrogen content of 10 ppm or higher,

[0043] -10 ppm or higher sulfur content, and

[0044] -Oxygen content of 10 ppm or higher.

[0045] When the density of the raw material is about 1g / ml (1000kg / m 3 ), the above concentrations given in mg / l are equivalent to the same concentrations given in ppm, i.e. 1 mg / l is equivalent to 1 ppm.

[0046] The content of heteroatoms (eg, chlorine, sulfur, oxygen, and nitrogen) in the feedstock can be determined by standard procedures, such as gas chromatography.

[0047] Furthermore, the feedstock preferably contains less than 10 wt.% fatty acids.

[0048] Fatty acid quantification can be performed according to standard procedures, for example, by gas chromatography coupled to a flame ionization detector (GC-FID). Preferably, the feedstock is characterized by a mixed carbonaceous feedstock comprising at least a first feedstock component as defined above and a second feedstock component, the second feedstock component comprising at least one of oils and waxes of synthetic or biological origin, sorted plastic waste (solids), biomass and mixed plastic waste (solids).

[0049] method

[0050] The present invention relates to a method for producing olefins by indirect gasification, wherein the method comprises the following steps:

[0051] a) feeding a feedstock containing fluid aliphatic hydrocarbons and / or cycloalkanes into a fluidized bed gasifier;

[0052] b) feeding a steam stream to the fluidized bed gasifier; and

[0053] c) gasifying the raw material in the fluidized bed gasifier;

[0054] Wherein, the step c) is carried out at a temperature in the range of 600°C to 900°C, preferably in the range of 700°C to 820°C.

[0055] Preferably, the process is carried out in an inert or quasi-inert atmosphere in a reactor.

[0056] In the context of this application, an inert atmosphere is characterized by being completely oxygen-free, a condition that can be achieved using gases such as N2, CO2, or any other gas that does not react with the feedstock molecules. A quasi-inert atmosphere consists of gases that have limited interaction with the hydrocarbons. For example, steam is a quasi-inert environment. It not only acts as a diluent in the hydrocarbon mixture, limiting the extent of runaway reactions (such as secondary free radical reactions) and limiting the formation of unwanted complex structures (such as polyaromatics and coke), but also plays an important role in determining the equilibrium of synthesis gas formation.

[0057] Preferably, the process is carried out at a steam to fuel (feedstock) ratio in the range of 1 to 5 (v / v).

[0058] The bed material used in the above method is not particularly limited and can be selected from inert and catalytically active bed materials. However, it is preferred that the bed material is inert. Silica sand is an exemplary inert bed material that can be used in the above method.

[0059] Preferably, the process is a continuous process.

[0060] Generally speaking, the starting materials used in step a) are the starting materials described above.

[0061] More specifically, it is preferred that the feedstock used in step a) comprises one or more fluid pyrolysis products, preferably one or more fluid pyrolysis products obtained from plastic waste that has not been subjected to a hydrogenation treatment.

[0062] Furthermore, it is preferred that the feedstock comprising fluid aliphatic hydrocarbons and / or cycloparaffins contains less than 10 wt.% fatty acids, based on the total weight of the feedstock.

[0063] Preferably, in the above process, at least a portion of the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes is in liquid state at ambient temperature and pressure (298 K; 1013 hPa).

[0064] Preferably, in the above process, at least a portion of said feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes and being in liquid state at ambient temperature and pressure is fed into the reactor as a spray.

[0065] Preferably, in the above process, at least a portion of the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes is in a gaseous state at ambient temperature and pressure.

[0066] Preferably, in the above method, the feedstock used in step a) contains 30 wt.% to 100 wt.%, preferably 40 wt.% to 100 wt.%, more preferably 50 wt.% to 100 wt.% of fluid aliphatic hydrocarbons and / or cycloalkanes, based on the total weight of the feedstock.

[0067] Preferably, the feedstock used in step a) is a mixed feedstock further comprising at least one of oils and waxes of synthetic or biological origin, sorted plastic waste, biomass and mixed plastic waste.

[0068] It is further preferred that the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes has at least one of the following:

[0069] - chlorine levels of 10 ppm or higher; and / or

[0070] - 10 ppm or higher sulfur content; and / or

[0071] - oxygen levels of 10 ppm or more; and / or

[0072] -Nitrogen content of 10 ppm or higher.

[0073] Preferably, step c) is performed at a temperature in the range of 650°C to 850°C, more preferably in the range of 700°C to 820°C.

[0074] Preferably, the method further comprises the following steps:

[0075] d) continuously monitoring the composition of the hydrocarbon product stream obtained from step c) by at least one gas analyzer; and

[0076] e) adjusting the composition of said feedstock comprised in step a) to obtain a mixed hydrocarbon stream of predetermined composition.

[0077] Preferably, the step a) comprises feeding the first carbonaceous feed component and the second carbonaceous feed component into the fluidized bed reactor through at least two separate inlets.

[0078] Preferably, the method further comprises the step of regenerating the solid bed material used in the fluidized bed reactor.

[0079] More preferably, the step of regenerating the bed material is performed in a fluidized bed combustor fluidly connected to a fluidized bed gasifier.

[0080] More preferably, said step of regenerating said solid bed material is performed at a temperature of 800°C to 1100°C.

[0081] Preferably, the combined content of ethylene and propylene recovered by the above process is at least 30 wt.%, more preferably at least 40 wt.%, based on the total aliphatic and / or cycloparaffinic content of the feedstock comprising fluid aliphatic and / or cycloparaffinic hydrocarbons. Preferably, the combined content of ethylene and propylene recovered by the above process is in the range of 30 wt.% to 50 wt.%, based on the total aliphatic and / or cycloparaffinic content of the feedstock.

[0082] Fluidized bed reactor components

[0083] The method according to the present invention is preferably carried out in a fluidized bed reactor system (or assembly). According to a particularly preferred embodiment, the fluidized bed reactor system comprises a dual fluidized bed reactor system, which comprises a reactor / gasifier and a regenerator / burner, wherein heating is provided to the solid bed material transferred to the reactor / gasifier bed. The reactor can be fed with a single feedstock comprising liquid aliphatic hydrocarbons and / or cycloalkanes. Alternatively, the reactor can be fed with two or more different feedstock components simultaneously, provided that at least one feedstock component is a feedstock comprising liquid aliphatic hydrocarbons and / or cycloalkanes.

[0084] Preferably, a fluidized bed reactor system suitable for implementing the method of the present invention comprises a fluidized bed gasifier, at least one gas analyzer connected to the product gas outlet fluid of the fluidized bed gasifier, and at least one control unit for adjusting the feedstock composition; wherein the fluidized bed gasifier comprises at least one inlet for introducing the mixed carbonaceous feedstock, preferably at least two inlets for introducing the mixed carbonaceous feedstock.

[0085] Preferably, the at least one inlet for introducing the mixed carbonaceous feedstock into the fluidized bed reactor assembly comprises an extruder.

[0086] Preferably, the at least one inlet for introducing the mixed carbonaceous feedstock into the fluidized bed reactor assembly is adapted to introduce the mixed carbonaceous feedstock into the gasifier in a liquid state (more preferably as a melt).

[0087] Optionally, the at least one inlet for introducing the mixed carbonaceous feedstock in a liquid state into a fluidized bed reactor assembly comprises a nozzle for spraying the mixed carbonaceous feedstock into the gasifier.

[0088] According to a particularly preferred embodiment, the fluidized bed reactor assembly comprises a dual fluidized bed reactor comprising a first fluidized bed reactor serving as a gasifier and a second fluidized bed reactor serving as a burner / regenerator. The first fluidized bed reactor and the second fluidized bed reactor are fluidically connected to each other.

[0089] The configuration of a dual fluidized bed (DFB) system can be compared to the more widely studied fluid catalytic cracking (FCC) unit. In a DFB system, hot fluidized bed material circulates between two interconnected fluidized beds: a burner (or regenerator) and a gasifier. The overall reaction on the burner side is exothermic, while on the gasifier side it is endothermic. The heat generated on the burner side is transported by the solid fluidized bed material to the gasifier side to meet its endothermic needs. This type of configuration allows the production of two independent gas streams: flue gas from the burner and product gas from the gasifier.

[0090] In a DFB system, solid bed material is continuously circulated between two interconnected fluidized beds. It is fully oxidized in the combustor (in the presence of air) and partially reduced in the gasifier (in the presence of hydrocarbon feed). The partially reduced bed material, along with unconverted solids, leaves the gasifier and enters the combustor. The unconverted solids are oxidized in the combustor along with the bed material.

[0091] Also in a DFB system, the two fluidized beds are preferably interconnected by a non-mechanical valve called a loop seal (LS). The loop seal allows the transfer of bed material between the two reactors without exchanging any gas. Typically, these loop seals are fluidized to avoid accumulation of hot bed material.

[0092] exist Figure 1 A schematic diagram of an exemplary DFB system is depicted in FIG, wherein the DFB system includes (1) a burner (or regenerator); (2) a fuel feed to the burner; (3) a cyclone separator; (4) a particle distributor; (5) a first loop seal for the gasifier; (6) a gasifier; (7) a second loop seal for the burner; and (8) a fuel feed to the gasifier. In addition, Figure 1 Also included are the sampling point (X) and the return point of the second loop seal (crossover ring).

[0093] Furthermore, details on conventional steam cracking reactor arrangements can be found, for example, in Ullmann's Encyclopedia of Industrial Chemistry (DOI: 10.1002 / 14356007).

[0094] Furthermore, a comparative example was performed using the reactor apparatus described in “Kusenberg, et al., Waste Management, 141 (2022), 104-114” (DOI: 10.1016 / j.wasman.2022.01.033).

[0095] use

[0096] The invention also relates to the use of a feedstock as defined above for producing olefins.

[0097] The present invention therefore relates to the use of a feedstock comprising fluid aliphatic hydrocarbons and / or cycloparaffins for the production of olefins.

[0098] Preferably, said feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes comprises one or more pyrolysis products as defined above.

[0099] Preferably, the use involves a feedstock containing less than 10 wt.% fatty acids based on the total weight of the feedstock.

[0100] Example

[0101] Material

[0102] Different feedstocks were used to demonstrate the versatility of the DFB system compared to conventional steam cracking units. The feedstocks studied were:

[0103] Fossil naphtha - Batch A (obtained from Borealis AG);

[0104] Fossil naphtha - Batch B (obtained from Preem Petroleum AB);

[0105] Pyrolysis oil from Renasci - Batch C (obtained from Renasci);

[0106] • Pyrolysis oil from Renasci - Batch D (obtained from Renasci).

[0107] PIONA (paraffins, isoparaffins, olefins, cycloparaffins, aromatics) analysis was performed on the various feedstocks used, and the results are presented in Table 3 below. Fossil naphtha generally has a very low olefin content. Lots A and C were analyzed by GC×GCFID / TOF-MS. Lots B and D were analyzed using GC-VUV.

[0108] Detailed characterization using GC-VUV

[0109] In order to determine the quality composition of raw material batch B and batch D, GC-VUV (Thermo Scientific TRACE 1310 model) analysis was carried out. The detailed information of the DGC-VUV analysis method for batch B and batch D is provided in Table 1. The analytical results (PIONA analysis) related to raw material batch B and batch D are given in Table 3.

[0110] Table 1: GC-VUV conditions and settings

[0111] Column Description ZB-1HT(30m×0.32mm×0.10μm) capillary Dimethicone polarity Non-polar Injector temperature 350℃ Detector temperature 325℃ Column flow <![CDATA[2 ml / min H2, constant flow]]> Split ratio 1:12 Initial temperature 35℃ Initial hold time 0min Heating rate 10℃ / min Target temperature 300℃ Final hold time 0min Total time 32min Detection substance range C5 to C18

[0112] Using this method, the GC-VUV system is able to detect and quantify all hydrocarbons in the boiling point range of C5 to C18.

[0113] To determine the mass composition of the samples, VUV analysis software (version 1.8.1) was used, developed by VUV Analytics in Texas, U.S.A. This software takes into account the relative response factor (RRF) of each species present in the gas sample to determine the mass composition of the sample.

[0114] Detailed characterization using GC×GC-FID / TOF-MS

[0115] All experiments were performed using three Thermo Scientific TRACE GC×GCs (Interscience, Belgium). For FID and MS analysis, the GC×GC conditions for the selected normal phase column combination (PONA×BPX-50) are shown in Table 2. The quantitative procedure was based on the method developed by Dijkmans et al., as published in:

[0116] -Industrial & Engineering Chemistry Research, 53(40), 15436-15446 (DOI: 10.1021 / ie5000888), and

[0117] -Fuel,140(0),398-406(DOI: 10.1016 / j.fuel.2014.09.055).

[0118] These analytical results relating to raw material batches A and C are given in Table 3 (PIONA analysis).

[0119] Table 2: GC×GC setup for offline analysis using FID and TOF-MS detectors

[0120]

[0121]

[0122] aDimethylpolysiloxane (Restek); b 50% phenylpolysilphenylene-siloxane (SGE); PTV: programmed temperature vaporization injector

[0123] The sample was quantitatively analyzed using GC×GC-FID. This analysis is based on peak surface area. The surface area of ​​a peak in the chromatogram is proportional to the amount of the corresponding component. Therefore, by integrating the peaks observed in the chromatogram, it is possible to quantitatively analyze the sample.

[0124] Known amounts of internal standards (3-chlorothiophene and 2-chloropyridine) were added to the samples for FID analysis. The internal standards for each chromatogram were chosen in such a way that they were properly separated from all other peaks (Dijkmans et al., DOI: 10.1016 / j.fuel.2014.09.055).

[0125] The amount of the added internal standard is selected in such a way that the internal standard has a similar peak height as the component quantified by the internal standard.

[0126] The mass fraction of each compound on FID (w i ) can be expressed as the mass fraction of the internal standard (3-chlorothiophene or 2-chloropyridine) w st To calculate:

[0127]

[0128] Among them, f i is the relative response factor of compound i, V i is the peak volume of compound i (corresponding to the sum of the peak areas recorded in the two-dimensional mode), f st is the relative response factor of the internal standard, V st is the peak volume of the internal standard. It has been shown that different isomeric hydrocarbons will produce only slightly different relative FID responses, so a reasonable approximation for the relative response factor (relative to methane) can be written as:

[0129]

[0130] Among them, M i is the molar mass of compound i, N c,i is the number of carbon atoms in compound i, M CH4 is the molar mass of methane. This approximation eliminates the need to calibrate for each compound present in the mixture. However, calibrations were performed for 3-chlorothiophene and 2-chloropyridine. Using the internal standard method, it was observed that the total weight fraction of this feed measured using GC×GC-FID was approximately 100 wt.% (± 5 wt.%). Therefore, the internal standard method was only used to check that the analysis was performed regularly, while the weight fractions of the individual compounds were calculated using internal normalization to 100 wt.%. All of these calculations were handled by an Excel macro written in-house.

[0131] Detailed qualitative characterization was achieved using information obtained from GC×GC-TOF-MS analysis, an existing mass spectral library (NIST), and Kovats retention indices (Kováts, Helvetica Chimica Acta, 41(7), 1915-1932; DOI: 10.1002 / hlca.19580410703). In addition, the structured chromatograms obtained by orthogonal GC×GC separation were used to assist in the identification of the components.

[0132] GC×GC-TOF-MS operation is computer-controlled, with GC peaks automatically detected as they emerge from the column. Each individual mass spectrum is recorded directly to a hard drive for subsequent analysis. This technique exploits common fragmentation pathways for various substances, providing identification information for each individual component obtained through chromatographic separation. Mass spectra are interpreted using XCalibur and / or Hyperchrom software.

[0133] Table 3: PIONA analysis results of exemplary raw materials (results are expressed as weight percentage of raw materials)

[0134]

[0135] Reactor device

[0136] Comparative Example - Conventional Steam Cracking Unit

[0137] Steam cracking pilot tests of pyrolysis oil were carried out in a hydrocarbon steam cracking pilot plant at the "Laboratorium voor Chemische Technologie" at the University of Ghent. In CE1a and CE1b, fossil naphtha (batch A) was used as the raw material. Details of the reactor apparatus can be found in Waste Management, 141 (2022), 104-114 by Kusenberg et al. Pyrolysis oil (batch C; 40%) was mixed with fossil naphtha (batch A; 60%) to obtain the raw materials for CE2a and CE2b. In order to determine the product yield and coking trend, various raw materials were processed in a steam cracking pilot plant with the furnace outlet temperature (COT) set to 840°C and 860°C, respectively. Throughout the test, the furnace outlet pressure (COP) was maintained at 1.7 bara, the hydrocarbon mass flow rate was 3.5 kg / h, and the dilution was 0.5 kg steam / kg hydrocarbon. DMDS (dimethyl disulfide) was added continuously to keep the sulfur content at 120 ppmw (ppmw = parts per million by weight).

[0138] Online product analysis was performed on the reactor effluent, and it was possible to characterize and quantify the different product components. C2 analysis of the quenched effluent gas was performed simultaneously on two gas chromatographs (GC) instruments. Hydrogen was only detected on one GC. Using two instruments to perform the same analysis allowed the consistency of the results to be checked. The first system was an Interscience Trace GC Ultra, known as the Refinery Gas Analyzer (RGA). Hydrogen, carbon dioxide, carbon monoxide, nitrogen, methane, ethane, ethylene and acetylene were all detected by a thermal conductivity detector (TCD). The second system was an InterscienceFisons GC 8340, known as a Permanent Gas Analyzer (PGA), equipped with a TCD that could detect the same compounds except hydrogen.

[0139] C1 to C4 compounds were also analyzed using an Interscience Trace GC Ultra with a flame ionization detector (FID). Comprehensive two-dimensional GC (referred to as GC×GC) was also used to measure the total content of C5+ compounds (hydrocarbons containing 5 or more carbon atoms), specifically benzene, toluene, styrene, and xylene (BTSX). The GC×GC instrument is coupled with an FID for quantitative analysis and a TOF-MS (time-of-flight mass spectrometer) for qualitative analysis. It can be used for both online analysis and offline analysis, as described above in the feedstock analysis section.

[0140] Coke formation in the radiant section was measured after 6 hours of cracking of three different feeds at COTs of 840°C and 860°C in both the radiant and convection sections of the pilot plant.

[0141] The analysis results of the products of the comparative examples are given in Table 4 (expressed as wt. % of the raw material).

[0142] Invention Example - Dual Fluidized Bed (DFB) System

[0143] Indirect gasification experiments were conducted in a Chalmers pilot plant DFB system consisting of a 12 MWth circulating fluidized bed (CFB) burner coupled to a 2-4 MWth bubbling fluidized bed (BFB) gasifier. This configuration allows the heat required for the gasification side to be obtained by recirculating the bed material from the burner. For steam gasification experiments, steam at a flow rate of 160 kg / h was used as the fluidizing medium in the gasifier. The liquid feedstock was pumped and fed directly into the gasifier as a spray. Silica sand was used as the bed material for all experiments.

[0144] To better understand the system, Figure 1 A schematic diagram of the apparatus is provided in .

[0145] In order to quantify the total dry gas produced during the test, a small flow of helium was added as a tracer gas (35lN / min) in the vaporizer. The raw gas stream was continuously sampled and used for permanent gases and condensable hydrocarbons (tar). In order to analyze the raw gas composition, the slip stream of the extracted raw gas was passed through a hot ceramic filter, cooled and washed in isopropanol to remove condensable hydrocarbons. This cold dry stream was then analyzed in a micro GC (Varian CP-4900). This micro GC has two channels and uses Porapplot Q and MS5 The microGC was operated with a chromatographic column and carrier gases of He and Ar, respectively. Dry, tar-free feed gas was sampled every 3 minutes (injection time 10-30 ms), with each injection producing a new chromatogram. The microGC was calibrated weekly using five concentration levels covering the expected concentration range. The substances analyzed were: H2, He, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H6, C3H8, and N2.

[0146] The gas composition results are the average of chromatograms taken during a period of stable operation (i.e., when the gasification temperature and fuel flow rate are stable). During this stable measurement period, the temperature within the gasifier was varied within a range of ±3°C. To measure the tar species, the same solid phase adsorption method as described in the previous section was used. In this case, a panel of four amines was sampled during stable operation. After elution, the resulting liquid was analyzed on a BRUKER 430 GC-FID. Each sample was analyzed three times, and the results presented are the average of the values ​​obtained from three replicate analyses of four different samples.

[0147] BTSX and aromatic substances are typically quantified using solid phase adsorption (SPA). In this method, a sample is drawn from the gas production line at a constant rate using a 100 mL syringe and passed through an adsorption column (Supelclean ENVI-Carb / NH2 SPE column) consisting of an amine adsorption layer (500 mg) and an activated carbon layer (500 mg). The adsorbed material is eluted into a vial using a mixture of dichloromethane, isopropanol, and acetonitrile (8:1:1). Hexylbenzene or 4-ethoxyphenol is added as an internal standard at concentrations suitable for quantification (approximately 12,000 mg / L and 250 mg / L, respectively). The vial is characterized on a Bruker GC430 gas chromatograph equipped with a flame ionization detector (FID) and a medium-polarity BR-17MS (BR85877) column, using H2 as the carrier gas. 28 different aromatic substances were detected, with boiling points ranging from C6 to C18, including monocyclic aromatics such as BTSX, and polycyclic aromatics such as naphthalene, anthracene, and triphenyl (C18). The product analysis results of the inventive examples are given in Table 5 (expressed in wt.% of the raw material).

[0148] Comparison of experimental results between comparative example and inventive example

[0149] The product distribution and yields of pyrolysis oil feedstock obtained from a comparative conventional steam cracking unit and a DFB gasification process are shown in Tables 4 and 5. The results are expressed as wt.% of the feedstock.

[0150] The results of the comparative experiment and the invention experiment were grouped according to the raw materials:

[0151] CE1a and CE1b: Batch A at two different temperatures (COT);

[0152] CE2a and CE2b: mixtures of batch C (40 wt.%) and batch A (60 wt.%) using two different temperatures (COT);

[0153] IE1a to IE1c: Batch D using three raw material mass flow rates and heating ratios;

[0154] IE2a to IE2c: Batch B using two different cracking temperatures.

[0155] As is apparent from Tables 4 and 5, the yields of ethylene and propylene are similar for the comparative example using a conventional steam cracking unit and the inventive example using a DFB gasification process. This result demonstrates that the DFB gasification process can replace the conventional steam cracking process to produce comparable amounts of ethylene and propylene from pyrolysis oil.

[0156] In conventional steam cracking units, olefins are known to cause coking of the cracking furnace tubes, increasing steam cracking unit downtime. Table 4 shows the total amount of coke formed in the comparative examples. In the inventive examples involving DFB gasification, coking is not considered a production limitation. This is because the continuous regeneration of the bed material during the DFB gasification process prevents production unit downtime associated with decoking of the steam cracking furnace.

[0157] Furthermore, during the thermal conversion process, contaminants containing heteroatoms, such as oxygen, chloride, cyanide, sulfur, and nitrogen, are converted into stable products such as CO2, HCl, H2S, HCN, and NH3 under specific operating conditions, thereby enabling recovery and avoiding operational problems. (Energy Fuel 23(5), (2009), 2743-2749 and Additives in Polymers, Modification of Polymer Properties, published by William Andrew, 2017, pp. 87-108.)

[0158] In fact, the Inventive Examples exhibited increased ethylene yields compared to the Comparative Examples. Overall, despite occurring at lower temperatures, the gasification yields of the Inventive Examples in the C1-C5 range matched or exceeded those obtained in the Comparative Examples. While the furnace tube outlet temperatures (COT) in the Comparative Examples are not directly comparable to the cracking temperatures of the DFB process (Inventive Examples), the results clearly demonstrate that a higher degree of cracking is possible in the DFB process at lower process temperatures.

[0159] The continuous regeneration of the heat carrying solid phase in the embodiments of the invention provides the additional benefit of removing coke from the production process, thereby minimizing or even avoiding complete interruption of production due to decoking of the equipment.

[0160] Furthermore, the DFB process (inventive example) resulted in a significantly lower aromatics yield compared to a conventional steam cracking unit (comparative example). At 780°C (IE2b), the total aromatics yield in the DFB process was 6 wt.%. On the other hand, the yield in a conventional steam cracking unit at 840°C was 17.34 wt.% (CE1a). This suggests that a higher degree of cracking at lower temperatures (as in the inventive DFB process) is beneficial because it reduces the yield of aromatics, which are less economically valuable than olefins. Furthermore, the reduced tendency to aromatize indicates a reduced tendency to coke.

[0161] As is clear from Table 3, the naphtha used in the Inventive Examples is of superior quality compared to the naphtha used in the Comparative Examples, taking into account both the cycloparaffinic and aromatic components. However, while the quality of the naphtha may contribute to some extent to the superior yields of the Inventive Examples, it is clear that the overall difference in product yields outweighs the difference in feedstock quality.

[0162] Another advantage of the process of the present invention can be seen in the examples (IE1a to IE1c) using pyrolysis oil as a feedstock, where conventional steam cracking is limited by coking due to the high content of unsaturated C-C bonds in the feed. Unsaturated C-C bonds are known to be the driving factor for coking in steam cracking, and the amount of unsaturated C-C bonds permitted in a steam cracker feed is limited. Due to the continuous regeneration / decoking described above, the process of the present invention is capable of processing this material. The pyrolysis oil examples (IE1a to IE1c) demonstrate olefinic naphtha yields without sacrificing ethylene yield.

[0163] Table 4: Comparative Example; Conventional Steam Cracking Unit

[0164]

[0165]

[0166] *BTSX = total amount of benzene, toluene, styrene and xylenes; measured by GC x GC as described above for the comparative examples.

[0167] Table 5: Inventive embodiment; DFB system

[0168]

[0169] *BTSX = total amount of benzene, toluene, styrene and xylenes; measured as described above for the inventive examples.

Claims

1. A method for producing olefins by indirect gasification, wherein the method comprises the following steps: a) feeding a feedstock containing fluid aliphatic hydrocarbons and / or cycloalkanes into a fluidized bed gasifier; b) feeding a steam stream into the fluidized bed gasifier; and c) gasifying the raw material in the fluidized bed gasifier; Wherein, the step c) is carried out at a temperature ranging from 600°C to 900°C.

2. The process according to claim 1, wherein the process is a continuous process.

3. The method according to any one of the preceding claims, wherein the feedstock comprises one or more fluid pyrolysis products, preferably one or more fluid pyrolysis products obtained from plastic waste, and more preferably one or more fluid pyrolysis products obtained from plastic waste that has not undergone hydrogenation.

4. The process according to any one of the preceding claims, wherein the feedstock comprising fluid aliphatic hydrocarbons and / or cycloparaffins contains less than 10 wt.% fatty acids, based on the total weight of the feedstock.

5. A process according to any one of the preceding claims, wherein the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes has a chlorine content of 10 ppm or more; and / or Sulfur content of 10 ppm or greater; and / or Oxygen levels of 10 ppm or greater; and / or Nitrogen content of 10 ppm or higher.

6. The method according to any one of the preceding claims, wherein step c) is performed at a temperature in the range of 650 to 850°C, preferably in the range of 700 to 820°C.

7. A process according to any one of the preceding claims, wherein at least a portion of the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes is in a liquid state at ambient temperature and pressure.

8. The process according to claim 7, wherein at least a portion of the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes and being in liquid state at ambient temperature and pressure is fed into the reactor as a spray.

9. A process according to any one of the preceding claims, wherein at least a portion of the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes is in a gaseous state at ambient temperature and pressure.

10. The process according to any one of the preceding claims, wherein the feedstock used in step a) comprises 50 to 100 wt.% of fluid aliphatic hydrocarbons and / or cycloalkanes, based on the total weight of the feedstock.

11. The method according to any one of the preceding claims, wherein the feedstock used in step a) is a mixed feedstock further comprising at least one of oils and waxes of synthetic or biological origin, sorted plastic waste, biomass and mixed plastic waste.

12. The method according to claim 11, further comprising the steps of: d) continuously monitoring the composition of the hydrocarbon product stream obtained from said step c) by at least one gas analyzer; and e) adjusting the composition of said feedstock comprised in step a) to obtain a mixed hydrocarbon stream of predetermined composition.

13. Use of a feedstock comprising fluid aliphatic hydrocarbons and / or cycloparaffins for the production of olefins.

14. Use according to claim 13, wherein the feedstock comprising fluid aliphatic hydrocarbons and / or cycloalkanes comprises one or more pyrolysis products obtained from plastic waste.

15. Use according to claim 13 or 14, wherein the feedstock contains less than 10 wt.% fatty acids, based on the total weight of the feedstock.

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