Catalytic aromatization of pyrolysis vapors

Abstract

This invention relates to the field of catalytic processes. In particular, this invention relates to a thermocatalytic pyrolysis process for the preparation of low molecular weight monocyclic aromatic compounds. The present invention provides a thermocatalytic pyrolysis process for preparing low molecular weight monocyclic aromatic compounds from a feed stream containing biomass and / or one or more polymers, comprising: a) subjecting a feed stream containing biomass and / or one or more polymers to a pyrolysis treatment at a pyrolysis temperature to generate pyrolysis vapors; b) optionally cooling or heating the pyrolysis vapors; c) in a catalytic conversion step, contacting the pyrolysis vapors with an aromatization catalyst at an aromatization temperature to produce a conversion product containing low molecular weight aromatic compounds; and d) optionally recovering the low molecular weight monocyclic aromatic compounds from the conversion product, wherein the catalytic conversion step c) is carried out in a smooth or bubble fluidized bed reactor.

Description

[Background technology]

[0001] This invention relates to the field of catalytic processes. In particular, this invention relates to a thermocatalytic pyrolysis process for the preparation of low molecular weight monocyclic aromatic compounds.

[0002] Low molecular weight monocyclic aromatic compounds such as benzene, toluene, and xylene (BTX) are important starting materials for a large number of chemicals, including ethylbenzene, cumene, cyclohexane, adipic acid (from benzene), toluene diisocyanate, benzaldehyde and benzoic acid (from toluene), and terephthalic acid (from p-xylene).

[0003] Currently, the aromatic compounds mentioned above are mainly produced through the refining processes of fossil resources such as crude oil or coal. Common processes include catalytic cracking such as steam cracking, steam reforming, fluid catalytic cracking, catalytic reforming, and coal tar distillation.

[0004] Alternatively, biomass, waste, or combinations thereof may be used for preparation or aromatics. Different types of biomass and / or waste can be used. Examples of usable waste include organic or biodegradable waste and mixed plastic waste. Several routes have been proposed for converting biomass or waste plastic materials into aromatics via chemical synthesis and / or thermochemical transformation.

[0005] The thermal conversion of biomass and / or mixed plastic waste into aromatics is a promising technique for reducing plastic waste and generating large quantities of chemicals, particularly for mixed and / or contaminated plastics that are not easily recyclable. Currently, these streams are incinerated and, in some cases, used to convert plastics into alternative fuels, but converting them into chemical building blocks for the chemical industry would bring significant value to these waste streams.

[0006] A thermal catalytic process for the preparation of low molecular weight monocyclic aromatic compounds is described in WO2020 / 204707. This document describes a two-step process comprising the steps of subjecting a feed stream containing plastic to a thermal decomposition treatment to generate thermal decomposition vapors, and in a catalytic conversion step, contacting the thermal decomposition vapors with an aromatization catalyst to produce conversion products containing low molecular weight aromatic compounds.

[0007] However, as described in WO2020 / 204707, the product stream does not consist entirely of aromatic compounds, but typically also contains gaseous compounds such as carbon dioxide, carbon monoxide, hydrogen, water, and low molecular weight alkanes, as well as by-products such as olefins and oxygenates. To obtain low molecular weight monocyclic aromatic compounds with higher purity and free of by-products, it is necessary to fractionate and / or purify the low molecular weight monocyclic aromatic compounds. WO2020 / 204707 shows that the BTX yield, expressed as wt% based on the organic fraction present in the plastic, depends on the raw materials and the temperature of the pyrolysis process.

[0008] Catalytic processes for producing aromatics can be carried out in fluidized bed reactors. A well-known example of a process for producing aromatics in a fluidized bed reactor is fluidized catalytic cracking (FCC). In FCC, not only cracking reactions occur, but aromatication reactions also play an important role. In FCC, riser reactors, more specifically Davison risers, are typically used, and a mixture of reactants / products and fluidized catalyst particles moves together upward in a plug-flow manner. These fluidization conditions are often referred to as fast fluidization. After reaching the top of the riser, the catalyst particles, to which coke has adhered, are regenerated and supplied to the bottom of the riser as fresh catalyst. To achieve these conditions, the flow rate of the reactants is relatively high compared to the diameter of the reactor, resulting in a relatively short residence time of the reactants / products in the catalyst bed.

[0009] Because the reactants / products and catalyst particles move together, a drawback of these high-speed fluidization conditions is that it is difficult to control the rate of catalyst regeneration independently of the space velocity in the reactor. Another drawback of using high-speed fluidization and / or riser reactors is that they are optimized for processes where catalyst particles are rapidly deactivated and immediate regeneration is required, and are less suitable for processes where the catalyst is deactivated more slowly. Other drawbacks include limited contact time between substrate and catalyst, plug-flow behavior, limited catalyst-substrate ratio, and the need for high structure.

[0010] The object of the present invention is to increase the yield of low molecular weight monocyclic aromatic compounds such as BTX, and / or reduce the amount of unwanted by-products such as oxygenates in the aromatization of pyrolysis vapors.

[0011] Another object of the present invention is to improve the energy efficiency of thermal catalytic processes for the preparation of low molecular weight monocyclic aromatic compounds.

[0012] Another objective is to provide a thermocatalytic process for the preparation of low molecular weight monocyclic aromatic compounds in which the space velocity and catalyst regeneration can be controlled independently of each other during the aromatization step. [Overview of the project]

[0013] The inventors have found that at least some of these objectives can be satisfied by carrying out the aromatization step of a thermal catalytic pyrolysis process in a smooth or buoyant fluidized bed reactor.

[0014] Accordingly, the present invention provides a thermal catalytic pyrolysis process for preparing a low molecular weight monocyclic aromatic compound from a feed stream containing biomass and / or one or more polymers, comprising: a) subjecting a feed stream containing biomass and / or one or more polymers to a pyrolysis treatment at a pyrolysis temperature to generate pyrolysis vapor; b) optionally cooling or heating the pyrolysis vapor; c) in a catalytic conversion step, contacting the pyrolysis vapor with an aromatization catalyst at an aromatization temperature to produce a conversion product containing a low molecular weight aromatic compound; and d) optionally recovering the low molecular weight monocyclic aromatic compound from the conversion product, wherein the catalytic conversion step c) is carried out in a smooth or bubble fluidized bed reactor.

[0015] By carrying out aromatization under smooth or buoyant fluidized bed conditions, the yield of low molecular weight monocyclic aromatic compounds such as BTX can be improved, and the amount of oxygenated material can be reduced compared to using other fluidized bed conditions such as high-speed fluidized bed conditions. In addition, the rate of catalyst regeneration can be controlled independently of controlling the gravimetric time-space velocity or the catalyst / supply ratio. This allows for greater flexibility in optimizing reaction conditions compared to high-speed fluidized bed conditions, where the catalyst regeneration rate is typically closely related to the space velocity. Furthermore, by applying smooth or buoyant fluidized bed conditions, the aromatization step becomes more flexible in adapting the conditions to changing raw materials. In particular, when using non-fossil raw materials such as biomass or mixed plastic waste, the variation in raw materials can be much greater compared to fossil raw materials.

[0016] The superiority of the smooth-bubble regime in terms of product quality is best demonstrated by very low concentrations of oxygen. In conventional aromatic plants, processing BTX flows requires low oxygen levels. In smooth or bubble fluidized bed reactors, oxygenation levels can be in the range of 5.0% by weight or less, such as 3.0% by weight or less, or even 2.0% by weight or less.

[0017] The advantages of carrying out the aromatization step in a smooth or bubbling fluidized bed reactor may include one or more of the following: · The smooth or bubbling fluidized bed regime allows for a wide range of WHSV and a broad fluid feed, which is particularly useful as the composition of the feed stream for the overall process (e.g., a mixed waste plastic and biomass mixture) can vary significantly. · A longer residence time (substrate-catalyst contact time) can be achieved compared to high-velocity fluidized bed conditions, enabling the maximization of so-called thermodynamic products (in contrast to kinetic products) and helping to convert unwanted oxygen to hydrocarbons. · Better product specifications: The product stream from the aromatization reactor can be very low in unwanted components such as oxygenates. · The equipment can be made more compact (e.g., a lower reactor height is required and a more compact cyclone can be used). · The smooth and bubbling fluidized bed regime is denser in the catalyst. · There is better mixing of the catalyst and the fluid, resulting in good and homogeneous mass and heat transfer, reducing the temperature difference along the fluidized bed and enabling constant catalyst conditions. · For example, the operation is not more complex compared to high-velocity fluidized bed conditions. · The deactivation of the fluidized bed catalyst occurs gradually throughout the entire bed due to the ideal mixing behavior of the smooth bubbling fluidized bed, reducing the differences in catalyst activity between individual particles in the smooth and bubbling fluidized beds and enabling constant conversion.

Brief Description of the Drawings

[0018] [Figure 1] Schematic diagram of part of the process according to the present invention. [Figure 2-3] Schematically shows different fluidized bed regimes. [Figure 4-8] Graph comparing the yields of different products when using a bubbling fluidized bed or plug flow conditions in the catalytic conversion step. [Modes for carrying out the invention]

[0019] According to the present invention, a thermocatalytic pyrolysis process is provided for the preparation of low molecular weight monocyclic aromatic compounds from a feed stream containing biomass and / or one or more polymers.

[0020] The thermal catalytic process includes a) a step of subjecting a feed stream containing biomass and / or one or more polymers to a thermal decomposition treatment at a thermal decomposition temperature to generate thermal decomposition vapor; c) a step of contacting the thermal decomposition vapor with an aromatization catalyst at an aromatization temperature in a catalytic conversion step to produce a conversion product containing a low molecular weight aromatic compound; and d) an optional step of recovering a low molecular weight monocyclic aromatic compound from the conversion product.

[0021] Depending on the temperature at which pyrolysis and aromatization are carried out, it may be necessary to heat or cool the pyrolysis vapor before aromatization. Therefore, the process may include an optional step b) of cooling or heating the pyrolysis vapor. However, if, for example, pyrolysis and aromatization are carried out at similar temperatures, heating or cooling the pyrolysis vapor may be undesirable or unnecessary.

[0022] According to the present invention, the catalyst conversion step c) is carried out in a smooth or bubble fluidized bed reactor.

[0023] As used herein, the term smooth or buoyant fluidized bed reactor refers to a reactor in which compounds present in the reactor, such as fluid reactants, fluid products, and catalyst particles, are subjected to smooth or buoyant fluidized bed conditions.

[0024] Preferably, the pyrolysis step a) and the catalytic conversion step c) are carried out in two different reactors, which allows the conditions in each reactor to be adapted to the desired conditions for each process.

[0025] The process described herein uses a feed stream containing biomass and / or one or more polymers. It will be understood that the composition of the pyrolysis vapor produced in step a) depends to some extent on the properties of the feed stream.

[0026] When the feedstream contains biomass, good results have been found with feedstreams containing biomass selected from the group consisting of agricultural waste, plants, wood, and combinations thereof. These types of biomass preferably include organic materials such as glucose, maltose, starch, cellobiose, cellulose, hemicellulose, other polysaccharides, lignin, sugarcane bagasse, lignocellulose materials (e.g., wood chips or shavings, lignocellulose biomass, etc.), glycerol, fatty acids, fatty acid methyl esters, triglycerides, food waste, animal waste, fertilizers, and corn stover. Partially decomposed vegetation such as peat or even lignite can also be used as biomass feedmaterial in the process of the present invention. When used, the biomass in the feedstream preferably contains crude glycerol and / or triglycerides. In addition to carbon and hydrogen, biomass typically contains heteroatoms such as oxygen, sulfur, and nitrogen.

[0027] The feed stream may contain one or more polymers, preferably one or more synthetic or semi-synthetic polymers, or mixtures thereof. For example, one or more polymers may be one or more selected from polyolefins such as polyethylene (PE), including high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP); polyesters such as polybutylene terephthalate (PBT) and polyethylene terephthalate (PET); acrylonitrile butadiene styrene (ABS); polystyrene (PS); polyamides; and aromatic polymers. One or more polymers in the feed stream may also be in the form of a plastic material. A plastic material typically contains a specific polymer (e.g., more than 25% by weight, preferably more than 40% by weight, more preferably more than 50% by weight of the total weight of the specific polymer), and the plastic is generally named after this specific polymer. In addition, a plastic material generally contains one or more additives such as fillers, reinforcing agents, processing aids, plasticizers, pigments, light stabilizers, lubricants, impact modifiers, antistatic agents, inks, and antioxidants.

[0028] Depending on any additives that may be present in the polymer and plastic materials, one or more polymers in the feed stream may also contain heteroatoms such as oxygen, sulfur, and nitrogen, as well as halogens such as chlorine and bromine.

[0029] Polymer or plastic materials may also be in the form of fiber-reinforced composites, multilayer plastics, metallized plastic bags (MPBs), mixed plastic waste, and / or recyclable waste. Preferably, the feed stream includes waste plastics such as post-consumer waste plastics, off-spec plastics, and industrial scrap plastics. The waste plastics may be single plastics or, preferably, mixed waste plastics.

[0030] The feedstream may also include a liquid stream derived from the thermal decomposition of one of the aforementioned biomass and polymer materials, and / or the feedstream may be pretreated, for example, by liquefaction, solvation, or slurrying of the feedstream.

[0031] In general, whether fluidized bed conditions are present in the reactor, and the fluidized bed regime, depend on several conditions such as the size and shape of the reactor, the density and size of the solid particles, the amount of catalyst, the flow rate, and the surface velocity of the fluid. The fluidization behavior of solid particles can be described, for example, using the Geldart particle classification. According to this classification, solid particles can be categorized into four types: A) permeable, B) granular, C) cohesive, and D) jet-like. Each of these particle types behaves differently at a given surface gas velocity, for example, as described in detail in D. Kunii and O. Levenspiel, Fluidization Engineering, 2nd edition, Butterworth-Heinemann, 1991. Preferably, the aromatic catalyst used in step c) comprises multiple solid catalyst particles of type A according to the Geldart classification. Whether multiple solid particles can be classified as Geldart type A is preferably established empirically, as described in the publications of Kunii and Levenspiel mentioned above. Alternatively, the definition of Geldart A-type particles that can be used is approximately 1400 kg / m³. 3 These are multiple solid particles having the following bulk densities and / or average particle size of 20-125 μm.

[0032] Figures 2 and 3 show schematic diagrams of fluidized bed regimes that can be encountered as the surface velocity (u) of the fluid in the reactor increases. Generally, fluidized bed conditions are those where the surface velocity of the fluid is at the minimum fluidization rate u mf This is achieved when it exceeds the minimum fluidization rate. When it exceeds the minimum fluidization rate, for example in the case of Geldart A particles, the fluidized bed regimes that can be encountered as the surface velocity increases are smooth fluidized bed, bubbly fluidized bed, and terminal velocity u tWhen exceeding this level: includes slugging and / or high-speed fluidized beds. In slugging and high-speed fluidized bed regimes, the degree of entrainment of catalyst particles in the fluid flow is increased. It is known in the art that reactors operating under plug-flow conditions, including entrained-flow fluidized bed (i.e., high-speed fluidized bed) reactors such as riser reactors, have higher conversion rates than smooth and / or bubbled fluidized bed reactors and are therefore used in petrochemical processes such as the FCC (J. Werther, Fluidized-Bed reactors, Ullmann's Encyclopedia of Industrial Chemistry (7th Ed.) 2011).

[0033] The inventors have found that using a smooth or buoyant fluidized bed for catalytic conversion of pyrolysis vapors obtained by pyrolysis treatment of a feed stream containing biomass and / or one or more polymers results in a higher yield of condensable products compared to using plug flow conditions. Surprisingly, high-speed fluidized bed conditions, which are typically applied to modern fluid catalytic decomposition processes and are generally considered to result in higher conversion, are not well-suited for the catalytic conversion step of the present invention. Therefore, in the process according to the present invention, entrainment of catalyst particles in the fluid stream is preferably prevented. While not wishing to be bound by theory, the inventors believe that stronger mixing and / or longer contact times between pyrolysis vapors and catalysts in a buoyant fluidized bed lead to more selective formation of low-aromatic compounds such as BTX.

[0034] The process described herein can convert a feed stream containing biomass and / or one or more polymers into a conversion product containing a significant proportion of lower molecular weight aromatics. Particularly preferred lower molecular weight aromatic compounds are benzene, toluene, and xylene (BTX). The proportion of BTX relative to the total weight of the condensed product may be at least 25% by weight, preferably at least 30% by weight, and more preferably at least 35% by weight. In embodiments, the yield of BTX relative to the total weight of the feed stream is 10% by weight or more, such as 5.0% by weight or more, preferably 7.0% by weight or more, more preferably 15% by weight or more, 20% by weight or more, 20% by weight or more, or even 25% by weight or more.

[0035] Low molecular weight monocyclic aromatic compounds (e.g., BTX) can be recovered from the conversion product, for example, by distillation. Other products, such as highly substituted aromatic fractions, can be recycled in the process of the present invention, for example, by co-feeding them with the feed stream described above to further increase the yield of low molecular weight monocyclic aromatic compounds. Before recycling the highly substituted aromatic compounds, they can be hydrogenated to polycyclic alkanes or partially hydrogenated to a mixture of polycyclic alkanes / polycyclic aromatic hydrocarbons / mono-aromatic polycyclic hydrocarbons.

[0036] As used herein, the terms smooth or bubbled fluidized bed conditions refer to conditions where the surface velocity of the fluid is the minimum fluidization rate u mf The above is true, and terminal velocity u tLess than, and refers to conditions where significant entrainment of catalyst particles can occur if the terminal velocity is exceeded. For example, by placing a gamma-ray source on one side of the reactor and measuring the intensity of the radiation transmitted at different heights along the reactor on the other side, empirical measurements can be carried out on the catalyst bed to evaluate in which fluidization regime the reaction operates or to what extent entrainment of catalyst particles occurs. Additionally or alternatively, for example, based on a figure such as the figure of FIG. 3, or based on a cold flow model which is a transparent model setting where catalyst particles are exposed to gases with different superficial velocities and the resulting fluidization regime can be observed, it is possible to calculate or predict the superficial flow rate and / or other conditions to be applied to achieve smooth or bubbling fluidized bed conditions.

[0037] As mentioned above, different parameters play a role in whether fluidization bed characteristics such as smooth or bubbling fluidized bed conditions are achieved in the reactor and what types of fluidization bed characteristics are achieved, and the parameters may need to be optimized for each specific application. Some exemplary values of these conditions are described in more detail below.

[0038] Preferably, the weight hourly space velocity is in the range of 0.1 to 10.0 hours -1 , preferably 0.25 to 2.0 hours -1 , or 0.5 to 2.0 hours -1 , more preferably 0.7 to 1.5 hours -1 . As used herein, the weight hourly space velocity (WHSV) is defined as the mass of the pyrolysis vapor (kg per hour) derived over the mass (kg) of the aromatization catalyst present in the aromatization reactor. For example, if 1000 kg of pyrolysis vapor per hour is passed through a 1000 kg catalyst bed, the WHSV is 1 hour -1 . In this formula, the mass of the aromatization catalyst refers to the total mass of the catalyst particles present in the aromatization reactor. If the catalyst particles contain, for example, an active domain (e.g., a zeolite domain) dispersed in an amorphous binder, the mass of the catalyst for calculating the WHSV refers not only to the mass of the active domain but also to the total mass of the catalyst particles.

[0039] In the embodiment, the gas flow rate of the pyrolysis steam entering the smooth or bubble fluidized bed reactor is 200 to 10,000 kg / hour, preferably 400 to 7,000 kg / hour.

[0040] In this embodiment, the amount of catalyst particles present in the aromatization reactor is 200 to 10,000 kg, preferably 400 to 7,000 kg.

[0041] In the embodiments, aromatization is carried out in a substantially cylindrical container, meaning that the horizontal cross-section of the container is substantially circular. Aromatization may also be carried out in a rectangular parallelepiped container, for example, if the container is made of a refractory material, meaning that the horizontal cross-section of the container is substantially square. Preferably, the container has a diameter of 0.5 to 4.0 m, more preferably 1.0 to 2.0 m.

[0042] The height of the vessel in which aromatization is carried out should be sufficient to accommodate a smooth or buoyant fluidized catalyst bed. For example, using the surface velocity and the particle size and density of the aromatization catalyst described herein, the height of the catalyst bed can be on the order of 2.0 m. Therefore, the height of the vessel is preferably 5.0 m or more, such as 5.0 to 15 m or 6.0 to 10 m.

[0043] Preferably, the aromatization catalyst is present in the aromatization reactor in the form of a plurality of solid catalyst particles. The catalyst particles preferably have an average particle size of 20 to 120 μm, such as 1 to 150 μm, and more preferably 30 to 100 μm.

[0044] The bulk density of the catalyst particles is 1400 kg / m³. 3 Preferably, the following ranges from 500 to 1300 kg / m³. 3 Within the range of 700-1000 kg / m², it is comfortable. 3 It could be within the range of.

[0045] Catalyst particles that may be particularly suitable as aromatization catalysts and / or particularly suitable for fluidization are, for example, commercially available FCC catalyst particles obtained from Ketjen Netherlands BV (formerly Albemarle Catalysts Company BV).

[0046] Preferably, the surface velocity of the pyrolysis vapor entering the aromatization reactor is 0.005 m / sec or more, preferably 0.01 to 1.0 m / sec, and more preferably 0.02 to 0.8 m / sec.

[0047] In the embodiment, step c) further includes the steps of: c1) producing a conversion product by contacting a pyrolysis vapor with an aromatizing catalyst at the aromatizing temperature to produce a carbonaceous deposit on the aromatizing catalyst; c2) separating the entrained fluid from the aromatizing catalyst containing the carbonaceous deposit in the catalyst circulation flow, preferably using a stripper; c3) regenerating the aromatizing catalyst in a regenerator, the regenerator also preferably being a smooth or buoyant fluidized bed reactor; and c4) supplying the regenerated aromatizing catalyst to the aromatizing reactor to obtain circulation of the aromatizing catalyst.

[0048] The separation of entrained fluids, such as fluid reactants, BTX, and / or other fluid products, from the catalyst can be carried out, for example, by stripping using nitrogen gas and / or vapor.

[0049] The regeneration of the aromatization catalyst is preferably carried out in the presence of oxygen, for example, by using air. Preferably, the regeneration is carried out at a regeneration temperature (T) of 500°C or higher, preferably 600°C or higher, more preferably 650°C or higher. reg This is carried out at a temperature below 900°C, such as 700-800°C. If the temperature is too high, the aromatization catalyst may be damaged. Therefore, it is preferable to carry out the regeneration of the aromatization catalyst at a temperature below 900°C, such as 700-800°C.

[0050] The frequency at which the aromatization catalyst should be regenerated can vary depending on the rate at which carbonaceous deposits form on the catalyst and the degree of catalyst deactivation caused by the formation of carbonaceous deposits. When using smooth or buoyant fluidized bed conditions, the catalyst circulation rate can be controlled independently of the gravimetric time-space velocity. This is in contrast to high-speed fluidization conditions in a riser (comparable to plug-flow conditions), where the catalyst moves along with the gaseous flow of reactants and products. In embodiments, the total amount of aromatization catalyst present in the aromatization reactor circulates between the aromatization reactor and the regenerator 0.2 to 20 times per hour, preferably 0.5 to 15 times per hour, and more preferably 1 to 10 times per hour.

[0051] Preferably, the regenerator also operates under smooth or buoyant fluidized bed conditions.

[0052] In this embodiment, contacting the pyrolysis vapor with the aromatization catalyst in a smooth or bubble fluidized bed reactor is performed at an aromatization temperature (T arom The process is carried out in a range of 500 to 575°C, preferably 300 to 650°C, more preferably 400 to 600°C, and more preferably 540 to 560°C.

[0053] After catalytic conversion in the aromatization reactor, the product gas can be separated from the catalyst particles, for example, by using a cyclone array, which may be located outside the aromatization reactor or in the freeboard section of the aromatization reactor. Due to smooth or buoyant fluidized bed conditions, the amount of entrained particles in the fluid product flow is typically small, as the surface velocity is much lower than the terminal velocity of most of the catalyst bed particles.

[0054] The gauge pressure upstream of the aromatization reactor is preferably 0.2 to 2.5 bar, more preferably 0.5 to 1.5 bar, or 0.5 to 2.0 bar.

[0055] The fluidized catalyst bed presents resistance to the fluid flow, which can lead to a pressure drop across the aromatization reactor. This pressure drop can range from 0.05 to 1.5 bar, for example, 0.10 to 1.0 bar.

[0056] The thermal decomposition treatment is performed at a thermal decomposition temperature (T) in the range of 400 to 700°C, preferably 400 to 600°C or 425 to 650°C. pyr ) can be implemented.

[0057] The aromatization reactor may be supplied with pyrolysis vapors via a gas distribution system, such as a plate or tube with tuyeres, or via a sparger, such as a ring sparger, orthogonal sparger, or a sparger with grid tubes. The advantage of such a distribution system is that the gas is well distributed, which has a positive effect on the fluidization of the floor. These systems can also be easily replaced as needed.

[0058] In the embodiment, the average residence time of the fluid in the smooth or buoyant fluidized bed present in the aromatization reactor is less than 2 minutes, preferably less than 1 minute, and more preferably less than 30 seconds. Typically, the average residence time of the fluid in the smooth or buoyant fluidized bed is 0.5 seconds or more, for example, 1.0 to 60 seconds or 2.0 to 45 seconds.

[0059] The aromatization catalyst may comprise one or more of zeolite catalysts, non-zeolite catalysts, metal catalysts, and / or metal oxide catalysts. In certain embodiments, the aromatization catalyst is a zeolite catalyst preferably selected from aluminosilicates, SAPO, silicates, and combinations thereof. It has been found that the aromatization catalyst is preferably acidic. The acidity may also be influenced by the structure of the aluminosilicate and by the ratio of silicate to aluminate moieties in the aluminosilicate. Suitable silica-alumina ratios include those in the range of 5 to 100, preferably 10 to 80, and more preferably 20 to 60. Another feature that may play a role in the performance of the catalyst is pore size. It has been found that particularly good results are obtained when the pore size of the aromatization catalyst is in the range of 4.5 to 6.5 Å, preferably 5 to 6 Å.

[0060] The zeolite catalyst is preferably selected from the group consisting of (S)AlPO-31, EU-1, ferrielite, IM-5, MCM-22, mordenite, SSZ-20, SSZ-23, SSZ-55, SUZ-4, TNU-9, zeolite A, zeolite beta, zeolite X, zeolite Y, ZSM-11, ZSM-23, ZSM-35, ZSM-5, ZSM-57, and combinations thereof, and may be treated, exchanged, or impregnated with metal to improve aromatic yield. In a particular embodiment, the zeolite catalyst is ZSM-5.

[0061] The metal can be selected from, in particular, nickel, platinum, vanadium, palladium, manganese, cobalt, zinc, copper, chromium, gallium, sodium, bismuth, tungsten, zirconium, indium, tin, thallium, lead, molybdenum, and / or their oxides.

[0062] The aromatic catalyst may further contain an amorphous binder. Therefore, the catalyst may suitably contain an amorphous binder in addition to the zeolite. The amorphous binder imparts strength, density, and shape to the particles thus obtained, and provides the catalyst particles with a consistent particle size. Therefore, the amorphous binder can be suitably selected from inorganic refractory oxides, particularly alumina, silica, silica-alumina, titania, zirconia, clay, layered mixed metal oxides, phosphates, sulfonates, and mixtures thereof.

[0063] When a binder is used, the amount of the binder in such a combination can vary over a wide range. Preferably, the amount of amorphous binder in the zeolite secondary catalyst is in the range of 30 to 80% by weight, preferably 40 to 70% by weight, based on the weights of the zeolite and amorphous binder. Such a ratio not only provides particles with sufficient mechanical strength but also, in the case of silica-alumina, provides a synergistic effect of increasing the yield of aromatic compounds compared to the yield expected proportionally. In the process according to the present invention, the aromatic catalyst can be regenerated by contacting the catalyst having carbonaceous deposits with oxygen to produce a regenerated aromatic catalyst.

[0064] Figure 1 shows a schematic overview of part of the process according to the present invention. Pyrolysis vapor (61) enters the bottom of the aromatization reactor (20). Product vapor (62) with catalyst particles and / or encompassed solid particles such as coke is led to a cyclone (21), where the catalyst particles and other solids are separated from the product vapor stream and supplied back to the aromatization reactor (20) (51). Product vapor (63) is led out of the cyclone (21). During the aromatization reaction, a catalyst circulation stream (55) is extracted from the fluidized catalyst bed. The catalyst particles in the catalyst circulation stream (55) typically contain catalyst particles with varying amounts of carbonaceous deposits. In the stripper (22), a recoverable fluid containing products such as BTX is stripped from the catalyst particles using stripper gas (71), and a stream (64) containing the stripper gas and recoverable fluid exits from the top of the stripper (22). A fluid-free catalyst circulation flow (56) is led to a regenerator (23) where carbonaceous deposits from catalyst particles are burned using a regenerating gas (72), such as air. The combustion gas (73) with entrained catalyst particles is led to a cyclone (26) used to separate the entrained catalyst particles from the combustion gas. The entrained catalyst particles (52) are led back to the regenerator, and the combustion gas (74), which typically contains regenerated gas concentrated with combustion products such as CO and / or CO2, exits the cyclone (26). The regenerated catalyst circulation flow (57) is led to a riser (24), and the riser gas (75) is used to transport the regenerated catalyst particles to a cyclone (25). In the cyclone (25), this flow is separated again with the regenerated catalyst particles (53) and riser gas (76), and the regenerated catalyst particles (53) are led back to the aromatization reactor (20). [Examples]

[0065] Example 1. The thermocatalytic pyrolysis process for preparing low molecular weight monocyclic aromatic compounds according to the present invention was carried out using mixed plastic waste (DKR350) and crude glycerol as feed materials, respectively.

[0066] Example 1-1. Mixed plastic waste (DKR350) as a raw material The raw material, which is a mixed plastic waste according to the DKR350 specification, is a mixture of different polymers such as polyethylene, polypropylene, polyethylene terephthalate, and polystyrene. DKR350 may also contain fractions of other polymers such as polyamide, polycarbonate, and other less common polymers. In addition, DKR350 contains fractions of bio-derived materials from various types of biomass. Analysis has shown that this raw material can contain up to 10% by weight of oxygen atoms. This oxygen can be present in the bio-derived fraction, but can also be present in the polymer fraction (e.g., polyethylene terephthalate).

[0067] Mixed plastic waste (DKR350) was subjected to a pyrolysis step in a pyrolysis reactor and a catalytic aromatization step in an aromatization reactor. The pyrolysis step was carried out in a reactor with an inner diameter of 168 mm, using silver sand (Geldart type B) with an average particle size of 225 μm as the heat transfer medium. The amount of sand packed into the pyrolysis reactor was 10 kg, resulting in a fluidized bed height of approximately 500 mm. A raw material supply rate of 5 to 10 kg / hour was used to supply the raw material to the pyrolysis reactor. The heat transfer medium in the pyrolysis reactor was fluidized using nitrogen gas at a rate of 2.5 kg / hour via a gas distribution plate. This resulted in a surface gas velocity of 0.07 to 0.1 m / s in the fluidized bed pyrolysis reactor, which corresponds to 2.5 to 3.0 times the minimum fluidization rate of the heat transfer medium used, indicating that bubbly fluidized bed conditions were present in the pyrolysis reactor. The residence time of the raw material in the fluidized bed was less than 2 seconds. The pyrolysis temperature (T) measured by at least two thermocouples located directly in the fluidized bed. pyr The temperature was 500-700°C, and the gauge pressure inside the pyrolysis reactor was 100-500 millibars.

[0068] The aromatization step was carried out in a fluidized bed aromatization reactor with an inner diameter of 256 mm. The average particle size was 70 μm, and the load was approximately 780 kg / m³. 3FCC-like catalyst particles (Geldart type A) with a fluidization density were used as the catalyst. The catalyst packing amount in the catalytic reactor was 10 kg. The surface gas velocity of 0.06 to 0.1 m / sec, which corresponds to approximately 30 to 60 times the minimum fluidization rate, indicates that there were bubbly fluidized bed conditions in the aromatization reactor. The WHSV was 0.5 to 1.0 hours. -1 The residence time in the catalyst bed was approximately 2 seconds. The aromatization temperature (T) was measured by a thermocouple located directly within the catalyst bed. arom The temperature was 550°C, and the gauge pressure inside the catalytic reactor was 20-300 millibars.

[0069] The BTX-rich product stream exiting the aromatization reactor was transferred to the condensation section, where the condensate was recovered as a liquid-phase product, leaving the soft components (non-condensable substances such as methane, hydrogen, carbon monoxide, carbon dioxide, and propane) in the gas phase. The liquid product was then analyzed. Benzene, toluene, and xylene were quantified using an internal standard method with octane as the internal standard, performed by GC-FID. The weight fractionation of oxygenated compounds was also determined. The results are shown in Table 1.

[0070] Examples 1-2. Crude glycerol as a raw material Besides glycerol itself, crude glycerol typically contains several contaminants, including ash (mainly potassium salts), water, and fatty acid methyl esters. It may also contain relatively small amounts of methanol. Analysis reveals that the ash level can be as high as 6% by weight, while the moisture level can be up to 5% by weight. The fatty acid methyl ester level can be as high as 10% by weight. Based on the atomic ratio of pure glycerol, the glycerol raw material contains approximately 52% by weight of oxygen atoms and is therefore oxygen-rich.

[0071] Crude glycerol was used as a raw material and subjected to thermal decomposition in a liquid-feed pyrolysis reactor, followed by aromatization in a fluidized-bed aromatization reactor. The aromatization reactor and the equipment for condensing and analyzing the product flow were the same as those described above for the example using mixed plastic waste as a raw material.

[0072] The pyrolysis step was carried out in a reactor with an inner diameter of 498 mm, and preheated raw materials were introduced using a spray nozzle. A raw material supply rate of 5-10 kg / hour was used to the pyrolysis reactor. The pyrolysis reactor was flushed with nitrogen gas at a rate of 2.0 kg / hour. The pyrolysis residence time in the pyrolysis reactor was several seconds. The pyrolysis temperature was 450-500°C (T), measured using a thermocouple located directly in the pyrolysis reactor. pyr The experiment was conducted at [location / location]. The gauge pressure inside the pyrolysis reactor was 100-500 millibars.

[0073] Aromatization was carried out in the same reactor used in the process where mixed plastic waste was the raw material. The catalyst packing amount was 15 kg. A surface gas velocity of 0.06–0.1 m / s, which corresponds to approximately 30–60 times the minimum fluidization rate, indicates that there were bubbly fluidized bed conditions in the aromatization reactor. The resulting WHSV was obtained in 0.5–1.0 hours. -1 The residence time in the catalyst bed was approximately 1-2 seconds. The catalyst was also the same as that used in the mixed plastic waste process. The aromatization temperature (T) was measured by a thermocouple located directly within the catalyst bed. arom The temperature was 550°C, and the gauge pressure inside the catalytic reactor was 20-300 millibars.

[0074] As with the case where the raw material was mixed plastic waste, the product flow was condensed and analyzed, and the results are shown in Table 1. [Table 1]

[0075] The product distribution shows that despite a large weight fraction of oxygen atoms present in the raw materials used, only oxygenated compounds with a low weight fraction are present in the product (this should not be confused with the weight fraction of oxygen atoms present in the product).

[0076] Comparative Example 1. The data obtained in Example 1 were compared with the data published in Jarvis et al., Energy Fuels 2018, 32, 1733. In this paper, vacuum gas oil mixed with 5 wt% biomass pyrolysis oxygenate was catalytically upgraded in a riser reactor (i.e., a Davison Circular Riser reactor) using an FCC catalyst. As can be seen in Figure 7 of this paper, a considerable proportion of oxygenates is present in the resulting product, even though only 5 wt% biomass pyrolysis oxygenate, corresponding to approximately 1.3 wt% oxygen content in the raw material, was added to the vacuum gas oil feed. This means that no significant oxygen removal occurs in the process of Jarvis et al. In comparison, since the proportion of oxygenated compounds in the product is lower than expected from Jarvis et al., considering the weight fractionation of oxygen atoms present in each raw material, there is more oxygen removal in Example 1. This indicates that the smooth or buoyant fluidized bed conditions used in the aromatization step of Example 1 actually result in higher oxygenate removal.

[0077] Example 2. Further experiments using different raw materials were conducted on bench-scale equipment designed to continuously process 100–200 g / hour of raw material. Different experiments used virgin polyethylene, DKR imitation (a defined raw material representing DKR350, consisting of a mixture of 50 wt% polyethylene, 30 wt% polypropylene, 10 wt% polyethylene terephthalate, and 10 wt% polystyrene), and a blend of polyethylene and pine wood (1:1 weight ratio) as raw materials, respectively.

[0078] Similar to Example 1, the raw materials were subjected to a pyrolysis step at 500°C in a pyrolysis reactor under buoyant fluidized bed conditions. 500g of sand was used as the heat transfer medium to control the minimum fluidization rate (U mf By using three times the amount of ), the conditions for a fluidized bed with bubbles were achieved.

[0079] Next, the vapor formed in the pyrolysis step was subjected to a catalytic conversion step in a separate aromatization reactor. The catalytic conversion step was carried out in the aromatization reactor at a temperature of 550°C. As the catalyst, 200 g of spray-dried catalyst particles with a particle size of 70-100 μm, containing ZSM-5 and a binder, were used under fluidized bed conditions. The weight-time-space velocity (WHSV) of the catalytic conversion step was 0.5-1.0 hours. -1 The experiment was conducted within this range and lasted 4 to 6 hours.

[0080] The products were categorized into gaseous products, liquid products (i.e., condensed vapor), and coke. The yield of liquid products was analyzed by GC-MS / FID using octane as an internal standard. "Oil" refers to the sum of all liquid (i.e., condensed) products excluding water.

[0081] Gas analysis was performed using online μGC with a mass flow rate of argon known as an internal standard.

[0082] The amount of coke retained on the catalyst was determined by regenerating the catalyst with air after the experiment was completed.

[0083] The yields of different products are shown in Figures 4-8 and Table 2. [Table 2]

[0084] In addition, for experiments where the feed stream contained oxygen (i.e., DKR imitation and PE: pine wood blend), the presence of oxygenates in the liquid product was analyzed again using GC-MS / FID data. Oxygenates detected in the liquid product included ketones, aldehydes, alcohols, carboxylic acids, esters, and phenols. The amount of oxygenates in the liquid product was estimated based on the relative peak area of ​​the oxygenates. The results are shown in Table 3. [Table 3]

[0085] Comparative Example 2. The same experiment as in Example 2 was carried out, except that in the catalyst conversion step, a fixed bed of 200 g of extruded material containing ZSM-5 and a binder was used instead of a fluidized bed.

[0086] In a stationary catalyst bed, as described above, contact between the reactants and the catalyst bed is controlled by plug flow conditions, similar to a riser reactor (i.e., a high-performance fluidized bed). Therefore, experiments using plug flow through a stationary catalyst bed can be used to simulate processes to which high-performance fluidized bed conditions (e.g., a riser reactor) are applied.

[0087] The results are shown in Figures 4-8 and Tables 2 and 3. Surprisingly, oil and BTX yields are higher when using fluidized bed conditions for the catalytic aromatization step compared to using plug flow conditions (in fixed bed or riser reactors, etc.).

[0088] In addition, in experiments where the raw materials contained oxygen atoms, i.e., DKR mimics and PE:pine wood blend, a decrease in the amount of oxygenated material was observed when bubble fluidized bed conditions were used, which indicates better deoxygenation of pyrolysis vapors compared to plug flow conditions (e.g., fixed bed reactor or riser reactor).

Claims

1. A thermocatalytic pyrolysis process for preparing low molecular weight monocyclic aromatic compounds from a feed stream containing biomass and / or one or more polymers, a) A step of subjecting the feed stream containing biomass and / or one or more polymers to a thermal decomposition treatment at a thermal decomposition temperature to generate thermal decomposition steam, b) Optionally, a step of cooling or heating the pyrolysis vapor, c) In the catalytic conversion step, the thermal decomposition vapor is brought into contact with the aromatization catalyst at the aromatization temperature to produce a conversion product containing a low molecular weight aromatic compound, d) optionally a step of recovering the low molecular weight monocyclic aromatic compound from the conversion product, A process in which the catalyst conversion step c) is carried out in a smooth or bubble fluidized bed reactor.

2. The process according to claim 1, wherein the pyrolysis step a) and the catalyst conversion step c) are carried out in two different reactors.

3. Step c) further produces carbonaceous deposits on the aromatic catalyst, and step c) c1) A step of extracting a fraction of the aromatization catalyst containing carbonaceous deposits from the aromatization reactor, thereby creating a catalyst circulation flow. c2) Preferably using a stripper to separate the entrained fluid from the aromatic catalyst containing carbonaceous deposits in the catalyst circulation flow, c3) A step of regenerating the aromatic catalyst in a regenerator, wherein the regenerator is preferably a smooth or buoyant fluidized bed reactor, c4) The process further includes supplying the regenerated aromatization catalyst to the aromatization reactor, thereby obtaining a circulation of the aromatization catalyst, The process according to claim 1 or 2, wherein the aromatic catalyst is recycled.

4. The process according to claim 3, wherein the total amount of aromatizing catalyst in the aromatizing reactor is circulated 0.2 to 20 times per hour, preferably 0.5 to 15 times per hour, more preferably 1 to 10 times per hour.

5. The gravitational space-time velocity is between 0.1 and 10.0 hours. －１ Preferably, 0.5 to 2.0 hours －１ , more preferably 0.7 to 1.5 hours －１ The process according to any one of claims 1 to 4.

6. The process according to any one of claims 1 to 5, wherein the surface velocity of the pyrolysis vapor in the aromatization reactor is 0.005 m / sec or more, preferably 0.01 to 1.0 m / sec, and more preferably 0.02 to 0.8 m / sec.

7. The process according to any one of claims 1 to 6, wherein the aromatic catalyst comprises a plurality of Geldart A-type solid catalyst particles.

8. The aromatic catalyst has an average particle size of 20 to 120 μm, preferably 30 to 100 μm, and / or 500 to 1300 kg / m³. ３ Preferably 700 to 1000 kg / m ３ The process according to any one of claims 1 to 7, comprising a plurality of solid catalyst particles having a bulk density.

9. In the smooth or bubble fluidized bed reactor, the thermal decomposition vapor is brought into contact with the aromatization catalyst at an aromatization temperature (T) in the range of 300 to 650°C, preferably 400 to 600°C, and more preferably 500 to 575°C. ａｒｏｍ The process according to any one of claims 1 to 8, carried out in )

10. The aromatizing catalyst is regenerated at a regeneration temperature (T) in the range of 650°C or higher, preferably 500°C or higher, more preferably 700-800°C or higher. ｒｅｇ The process according to any one of claims 3 to 9, to the extent dependent on claim 3, carried out in )

11. The process according to any one of claims 1 to 9, wherein the gauge pressure upstream of the aromatization reactor is 0.2 to 2.5 bar, preferably 0.5 to 2.0 bar, and the pressure drop across the aromatization reactor is 0.05 to 1.5 bar.

12. The thermal decomposition treatment is performed at a thermal decomposition temperature (T) in the range of 400 to 700°C, preferably 425 to 650°C. ｐｙｒ The process according to any one of claims 1 to 11, carried out in )

13. The process according to any one of the prior claims, wherein the residence time of the gas in the smooth or bubble fluidized bed reactor is less than 2 minutes, preferably less than 1 minute, and more preferably less than 30 seconds.

14. The process according to any one of the prior claims, wherein the aromatic catalyst comprises one or more selected from the group consisting of ZSM-5, ZSM-11, ZSM-35, ZSM-23, ferriate, zeolite beta, zeolite Y, zeolite X, mordenite, zeolite A, IM-5, SSZ-20, SSZ-55, MCM-22, TNU-9, metal-treated, replaced, or impregnated catalysts, and combinations thereof.

15. The process according to claim 14, wherein the aromatic catalyst further comprises an amorphous binder.

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