Method for Simultaneously Producing Lower Aliphatic Hydrocarbons and Aromatic Hydrocarbons

Abstract

To provide a simultaneous production method of lower aliphatic hydrocarbons and aromatic hydrocarbons useful as petrochemicals, even though hydrocarbon-based plastics obtained from the lower aliphatic hydrocarbons and the aromatic hydrocarbons have conventionally been difficult to be used as raw materials because the lower aliphatic hydrocarbons and the aromatic hydrocarbons contain a wide variety of components.SOLUTION: When producing the lower hydrocarbons and the aromatic hydrocarbons from thermally-decomposed products of hydrocarbon plastics, a simultaneous production method of lower aliphatic hydrocarbons and aromatic hydrocarbons comprises steps of: heating and melting at least hydrocarbon-based plastics (1); thermally decomposing heat-melted hydrocarbon-based plastics in presence of a zeolite having a solid acid content of 200 μmol / g or less to obtain a thermally-decomposed product (2); and simultaneously producing the lower aliphatic hydrocarbons and the aromatic hydrocarbons by bringing the thermally-decomposed product into contact with a catalyst containing zeolite satisfying specific characteristics under a heating condition (3).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for producing lower hydrocarbons and aromatic hydrocarbons from hydrocarbon-based plastics. Specifically, aliphatic hydrocarbons composed of paraffins, olefins, diolefins, etc. having 1 to 30 carbon atoms (hereinafter sometimes referred to as C), which are the main components of the pyrolysis products of hydrocarbon-based plastics, are subjected to specific processes using two specific types of zeolite catalysts, thereby enabling highly efficient, balanced, and stable conversion of olefins, paraffins, and aromatic hydrocarbons having 2 to 8 carbon atoms, which are useful as petrochemical products, into lower aliphatic hydrocarbons and aromatic hydrocarbons. The present invention relates to a method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons.

Background Art

[0002] In recent years, the issues of global warming and marine plastics have been spotlighted, and chemical recycling, which chemically decomposes waste plastics and reuses them as raw materials for petrochemical products, has attracted attention. Among them, the oil conversion technology by pyrolysis is an important technology that can substantially enable the recycling of plastics by converting thermoplastic polyolefins (polyethylene, polypropylene), which account for half of waste plastics, into hydrocarbon oil and using this hydrocarbon oil as a raw material for naphtha crackers and the like.

[0003] The oil conversion technology by pyrolysis of waste plastics has been known for a long time. When pyrolysis is carried out under anaerobic and catalyst-free conditions, products with a wide carbon number distribution range of C1 to C30, that is, hydrocarbon oil, can be obtained. Among these, light oil with C5 to C10 can be used as a raw material oil for naphtha crackers, but kerosene, gas oil, heavy oil, and wax with C11 or more are used as fuels and do not have a high added value as products.

[0004] As a method for increasing the added value of products, a method has been proposed in which polyolefin-based (waste) plastics are pyrolyzed, and the products generated by pyrolysis are brought into contact with a catalyst layer such as zeolite to recover hydrocarbon oil (see, for example, Patent Document 1 and Non-Patent Document 1).

[0005] In addition, a method for treating waste plastics (see, for example, Patent Document 2) has been proposed in which a pyrolysis product obtained by vaporizing waste plastics by pyrolysis is brought into contact with a boron-containing silicate catalyst to recover hydrocarbon oil. Further, a method for treating waste plastics using a gallium-containing silicate catalyst (see, for example, Patent Document 3), etc. have been proposed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in the method proposed in Patent Document 1, by using a ZSM-5 catalyst, the carbon number distribution of hydrocarbon oil is reduced from C5 to C38 to C5 to C21, but still there is a problem that there are many fractions of kerosene, light oil, and heavy oil with low added value of C11 or more. In the method proposed in Non-Patent Document 1, in addition to ZSM-5, HY, REY, and Ni / ReY catalysts are used for pyrolysis. In particular, when the REY catalyst is used, the selectivity of the gasoline fraction of C5 to C11 is increased, but these Y-type zeolites have poor thermal stability and there are still many fractions with low added value of C9 or more, and they are not sufficient as industrial catalysts.

[0009] In the method proposed in Patent Document 2, by using a boron-containing silicate catalyst, the reduction of the molecular weight of hydrocarbon oil progressed significantly. In particular, although the total selectivity of C3 and C4 olefins and paraffins increased, the production of biased components made it difficult to use in combination with existing plants. For example, the load on a specific distillation column in an ethylene plant (naphtha cracker) increased, and it was necessary to excessively reduce the operating rate of the naphtha cracker, or a new specific distillation column had to be installed. Therefore, the economic rationality was low. In addition, because the synthesis of boron-containing silicate is difficult, there are difficulties in obtaining it, and the coke resistance is not sufficient, and satisfactory consideration has not been given in terms of catalyst life. Furthermore, in the method proposed in Patent Document 3, by using a gallium-containing silicate catalyst, the carbon number distribution is C1 to C13, and in particular, the selectivities of benzene (C6), toluene (C7), and xylene (C8) increase, and the reduction of the molecular weight progresses in a well-balanced manner. However, gallium-containing silicate, especially gallosilicate, is difficult to insert Ga metal into the skeleton of silicate, and it is difficult to synthesize it reproducibly and industrially. In addition, because the coke resistance is not sufficient, there is still room for improvement in terms of catalyst life.

[0010] Therefore, the emergence of a production method that can efficiently, highly selectively, and simultaneously convert the pyrolysis products of hydrocarbon-based plastics into lower aliphatic hydrocarbons and aromatic hydrocarbons useful as petrochemical products has been desired.

Means for Solving the Problems

[0011] As a result of intensive studies to solve the above problems, the present inventors have found that when producing lower hydrocarbons and aromatic hydrocarbons from the pyrolysis products of hydrocarbon-based plastics, by passing through a specific process using two specific zeolite catalysts, lower aliphatic hydrocarbons and aromatic hydrocarbons useful as petrochemical products can be simultaneously produced in high yields, and moreover, a production method excellent in catalyst life is obtained, and thus the present invention has been completed.

[0012] That is, the present invention relates to a method for producing lower aliphatic hydrocarbons and aromatic hydrocarbons using a hydrocarbon-based plastic as a raw material, and is characterized by passing through at least the following steps (1) to (3), and relates to a method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons. (1) Step: A step of heating and melting the hydrocarbon-based plastic. (2) Step: A step of thermally decomposing in the presence of a zeolite in which the acid amount (solid acid amount by the NH3-TPD method) determined from the high-temperature desorption amount in the ammonia temperature-programmed desorption spectrum of the heat-melted hydrocarbon-based plastic is 200 μmol / g or less to obtain a thermal decomposition product. (3) Step: A step of simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons by bringing the thermal decomposition product into contact with a catalyst containing a zeolite that satisfies the following characteristics (i) to (iv) under heating conditions. (i) The average particle size is 100 nm or less. (ii) A 10-membered ring pore zeolite of the MFI type or MEL type. (iii) The Bronsted acid amount on the outer surface is 0.1 to 10.0 μmol / g. (iv) The total Bronsted acid amount is 0.01 to 1.0 mmol / g.

[0013] The present invention will be described in detail below.

[0014] The production method of the present invention is a method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons useful as petrochemical products, even for hydrocarbon-based plastics that conventionally have been difficult to use as raw materials because they contain a wide variety of components. It includes the steps of: (1) heating and melting the hydrocarbon-based plastic; (2) thermally decomposing the heated and melted hydrocarbon-based plastic in the presence of a zeolite with an acid amount (solid acid amount by NH3-TPD method) determined from the high-temperature desorption amount in the ammonia temperature-programmed desorption spectrum of 200 μmol / g or less to obtain a thermally decomposed product; and (3) contacting the thermally decomposed product with a catalyst containing a zeolite satisfying the characteristics of (i) an average particle size of 100 nm or less, (ii) a 10-membered ring microporous zeolite of the MFI type or MEL type, (iii) a Bronsted acid amount on the outer surface of 0.1 to 10.0 μmol / g, and (iv) a total Bronsted acid amount of 0.01 to 1.0 mmol / g under heating conditions to simultaneously produce lower aliphatic hydrocarbons and aromatic hydrocarbons. A schematic diagram of a preferred embodiment at that time is shown in FIG. 1.

[0015] The production method of the present invention uses hydrocarbons, which are pyrolysis products of hydrocarbon-based plastics, as raw materials, and through steps (1) to (3), it is possible to simultaneously and highly selectively produce hydrocarbons, particularly lower hydrocarbons useful as petrochemical products, that is, lower aliphatic hydrocarbons and aromatic hydrocarbons having 2 to 8 carbon atoms. The pyrolysis products of hydrocarbon-based plastics as raw materials at that time are not limited as long as they are obtained by pyrolyzing hydrocarbon-based plastics. Among them, by reusing plastic waste as resources again, it is possible to contribute to solving social issues in both resource conservation and waste treatment. Therefore, hydrocarbon-based plastics that do not have oxygen atoms or nitrogen atoms in their structure and exhibit thermoplasticity, and furthermore, used waste plastics and / or pyrolysis products of waste products during the production and processing of hydrocarbon-based plastics are preferably used. Examples of hydrocarbon-based plastics include polyethylene, polypropylene, ethylene-propylene rubber, polystyrene, etc. Further, plastics obtained by separating and removing chlorine atoms from chlorinated plastics composed of vinyl chloride resin, vinylidene chloride resin, and chlorinated polyethylene are included.

[0016] Step (1) constituting the production method of the present invention is a step of heating and melting a hydrocarbon-based plastic. As long as the hydrocarbon-based plastic is heated and melted and the melted plastic can be supplied to the subsequent step (2), the apparatus, method, etc. are not particularly limited. For example, a single-screw or twin-screw extrusion melter heated by a heat medium jacket or a heating heater, a stirred autoclave, etc. are used. The temperature during heating and melting is not particularly limited as long as the hydrocarbon-based plastic is heated and melted. For example, 140°C to 300°C is preferable, and 160 to 250°C is more preferable.

[0017] The (2) process that constitutes the manufacturing method of the present invention is a process of thermally decomposing a heat-melted hydrocarbon-based plastic in the presence of a zeolite having a solid acid amount of 200 μmol / g or less by the NH3-TPD method to obtain a thermal decomposition product. If the mixture of aliphatic hydrocarbons composed of paraffins, olefins, and diolefins with a carbon number distribution of C1 to C30, which is the thermal decomposition product, can be further reduced in molecular weight and supplied to the (3) process, the process and apparatus are not particularly limited. For example, a method in which a heat-melted hydrocarbon-based plastic comes into contact with a zeolite having a solid acid amount of 200 μmol / g or less by the NH3-TPD method can be mentioned. Specifically, a method of supplying a heat-melted hydrocarbon-based plastic to a thermal decomposition apparatus such as a single-screw or twin-screw extrusion melter heated by a heat medium jacket or a heating heater, or a stirred autoclave, and supplying a zeolite having a solid acid amount of 200 μmol / g or less by the NH3-TPD method can be mentioned. Furthermore, the above-mentioned (1) process and the (2) process can be carried out simultaneously or sequentially in the same apparatus.

[0018] (2) The shape of the zeolite in the process is not particularly limited. Among them, a powder shape is preferable because it is easy to handle. There is no particular limitation on the reaction temperature. A range of 200 to 600 °C is preferable because thermal decomposition proceeds more efficiently, and a range of 250 to 500 °C is more preferable because the reduction in molecular weight proceeds more. There is also no limitation on the reaction pressure. For example, it can be operated in a pressure range of normal pressure to about 5 MPa. When supplying the heat-melted hydrocarbon-based plastic and the zeolite, it can also be used after being diluted with an inert gas such as nitrogen.

[0019] (2) The zeolite used in the process is a zeolite with an acid amount determined from the high-temperature desorption amount in the ammonia temperature-programmed desorption spectrum of 200 μmol / g or less. Here, the solid acid amount of the zeolite by the NH3-TPD method is a value measured by the NH3-TPD method in accordance with "Measurement of Solid Acid Properties by Ammonia Temperature-Programmed Desorption Method, Catalysis, vol. 42, p. 218 (2000)". That is, the solid acid amount of the zeolite in the present invention by the NH3-TPD method is a value obtained by measuring the amount of ammonia desorbed from a sample saturated with ammonia at room temperature at 100°C or higher and 500°C or lower. Specifically, it is obtained by the measurement of the solid acid amount by the NH3-TPD method described later.

[0020] (2) The zeolite used in the process has a solid acid amount by the NH3-TPD method of 200 μmol / g or less. Within this range, the yield of relatively lower aliphatic hydrocarbons (olefins, paraffins, diolefins) with carbon numbers ranging from C1 to C20 is high. By supplying this aliphatic hydrocarbon to step (3), a catalytic reaction by the catalyst containing zeolite in step (3), that is, the efficient simultaneous production of lower aliphatic hydrocarbons and aromatic hydrocarbons by further lower-leveling and cyclization of aliphatic hydrocarbons is made possible. Further, the framework structure of the zeolite is not particularly limited, and as the structure code consisting of three capital letters of the alphabet defined by the International Zeolite Association, for example, ABW, AFG, ANA, * BEA, BIK, BOG, BRE, CAN, CAS, CFI, CHA, DAC, DDR, EAB, EDI, EMT, EPI, ERI, ESV, EUO, FAU, FER, FRA, GIS, GME, GOO, HEU, IFR, ITE, JBW, KFI, LAU, LEV, LIO, LOS, LTA, LTL, LTN, MAZ, MEI, MEL, MER, MFI, MFS, MON, MOR, MSO, MTF, MTN, MTT, MTW, MWW, NAT, NES, NON, OFF, -PAR, PAU, PHI, RHO, RTS, RUT, SFE, SFF, SFG, SOD, SST, STF, STI, STT, TER, THO, TON, TSC, UFI, VET, VFI, WEN, YUG, etc. can be mentioned. Since it has high catalytic activity and is easily available, preferably* BEA, FAU, FER, LTA, LTL, MFI, MOR, MWW, and more preferably FAU and MFI are mentioned.

[0021] In addition, the composition of the zeolite is not particularly limited. For example, aluminosilicates; metalloaluminosilicates such as borosilicate aluminosilicate, titanosilicate aluminosilicate, vanadium aluminosilicate, manganese aluminosilicate, iron aluminosilicate, zinc aluminosilicate, gallium aluminosilicate, tin aluminosilicate; and metallosilicates such as borosilicate, titanosilicate, vanadium silicate, manganese silicate, iron silicate, zinc silicate, gallium silicate, tin silicate are used. Among these, aluminosilicates are preferably used because they are easily available at the industrial level.

[0022] Here, the above aluminosilicate is generally M 2 / nIt is preferably an aluminosilicate of the proton type, represented by the composition of O·Al2O3·xSiO2·yH2O (where n is the valence of the cation M, x is a number of 2 or more, and y represents the water adsorption amount). Also, x is called the SiO2 / Al2O3 ratio and is a numerical value that serves as an index representing the heat resistance, acid resistance, solid acidity, and reactivity of zeolite. There is no particular limitation as long as the amount of solid acid by the NH3-TPD method is 200 μmol / g or less. Since the yield of relatively lower aliphatic hydrocarbons with a carbon number distribution of C1 to C20 is high, the proton type aluminosilicate with a SiO2 / Al2O3 ratio of preferably 100 or more, more preferably 200 or more is used. The method for producing a proton type aluminosilicate with a SiO2 / Al2O3 ratio of 100 or more at that time is not particularly limited. For example, an aluminosilicate is synthesized by a hydrothermal synthesis method in which a mixture of a silica source, an alumina source, an alkali source, and water is heated in a sealed system. In the hydrothermal synthesis method, since an aluminosilicate with a structurally stable SiO2 / Al2O3 ratio of 5 to 50 is often generated, an aluminosilicate with a desired SiO2 / Al2O3 ratio of 100 or more is synthesized by various methods such as hydrothermal (steam) treatment and acid treatment. Since the cation M of the aluminosilicate generated by hydrothermal synthesis is an alkali metal, the conversion to the proton type can be easily performed by a method of heating after ion exchange to the ammonium type or a method by acid treatment.

[0023] The zeolite exhibits high catalytic performance as it is, but since the amount of solid acid by the NH3-TPD method can be efficiently adjusted, it preferably contains at least one metal selected from metals belonging to Group IA and Group IIA of the periodic table. Its content is not particularly limited as long as the amount of solid acid by the NH3-TPD method is 200 μmol / g or less, and it is preferably zeolite with a content of 0.05 to 5.0 wt%. Among these metals, calcium and sodium are more preferable because they have a high yield of relatively lower aliphatic hydrocarbons with a carbon number distribution of C1 to C20 and high heat resistance. The method for producing an aluminosilicate containing at least one metal selected from metals belonging to Group IA and Group IIA of the periodic table is not particularly limited, and a method of introducing a metal by an ion exchange method using the above-mentioned proton-type aluminosilicate is used. Also, the amount of the metal to be ion-exchanged may be appropriately used so that the metal content becomes the desired content.

[0024] In addition, since the amount of solid acid by the NH3-TPD method can be precisely adjusted for the zeolite, it is preferably a zeolite in which part or all of the surface OH groups are silylated. The silylation treatment of the zeolite is not particularly limited. For example, using the above-mentioned proton-type aluminosilicate, it can be easily treated by appropriately treating with a silylating agent such as hexamethylsilazane, trimethylsilyl chloride, t-butyldimethylchlorosilane, or butylchlorodimethylsilane.

[0025] In addition, as an embodiment of the (2) process, since it enables particularly efficient decomposition, at least the following steps are preferred: (a) a first decomposition step of thermally decomposing a molten hydrocarbon-based plastic without oxygen and without a catalyst; and (b) a second decomposition step of contacting and thermally decomposing with zeolite after the step (a) to obtain a thermally decomposed product. It is preferable to adopt a process that includes steps (a) and (b). A schematic diagram of a preferred embodiment at that time is shown in FIG. 2. Here, the apparatus for step (a) is not particularly limited, and a thermal decomposition apparatus such as a single-screw or twin-screw extrusion melting machine heated by a heat medium jacket or a heating heater, or a stirred autoclave is preferably used. The temperature is not particularly limited, and a range of 200 to 600 ° C is preferred because thermal decomposition proceeds more efficiently, and a range of 250 to 500 ° C is more preferred because lower molecular weight products are more likely to be obtained. There is no limitation on the reaction pressure either, and for example, it can be operated in a pressure range of normal pressure to about 5 MPa. Further, when supplying the molten hydrocarbon-based plastic and zeolite, it can also be used after being diluted with an inert gas such as nitrogen.

[0026] In addition, the apparatus for step (b) is not particularly limited, and a fixed-bed flow-type catalytic reaction process is preferably used. The shape of the zeolite can be any shape, and since it is easy to handle, a granular shape is preferred. Examples thereof include cylindrical shapes, cylindrical shapes, triangular prism shapes, quadrangular prism shapes, pentagonal prism shapes, hexagonal prism shapes and other polygonal prism shapes, hollow polygonal prism shapes, spherical shapes, etc. Among them, a cylindrical shape or a cylindrical shape is preferred because it is excellent in continuous productivity and has a high crushing strength. Further, the size such as its diameter, width, length, etc., and the density such as bulk density and true density can be arbitrarily selected in consideration of filling efficiency, etc. In particular, since it becomes a catalyst capable of supplying an aliphatic hydrocarbon having a carbon number distribution suitable for step (3), it preferably has a cylindrical shape with a diameter of 1.0 to 10 mm or a cylindrical shape with a thickness of 0.5 to 5.0 mm. The temperature is not particularly limited, and a range of 200 to 600 ° C is preferred because thermal decomposition proceeds more efficiently, and a range of 250 to 500 ° C is more preferred because lower molecular weight proceeds. There is no limitation on the reaction pressure either, and for example, it can be operated in a pressure range of normal pressure to about 5 MPa. The supply of the thermal decomposition product is not particularly limited as the ratio of the volume of the thermal decomposition product gas to the volume of the zeolite catalyst body. For example, 1 h -1 ~50000 h -1 The space velocity of about can be mentioned. In that case, it can also be used as diluted with a single or mixed gas selected from inert gases such as nitrogen, hydrogen, carbon monoxide, and carbon dioxide.

[0027] In addition, there is a step of separating the thermal decomposition product into a high-boiling component and a low-boiling component by distillation between the step (a) and the step (b). The step (b) is a step of contacting and thermally decomposing the high-boiling component and the zeolite. Further, as the step (d), a process that passes through a step of mixing the low-boiling component of the step (a) and the decomposition product of the step (b) to form a thermal decomposition product is a more preferred embodiment, and a schematic diagram thereof is shown in FIG. 3. Here, as long as the distillation can separate the high-boiling component and the low-boiling component from the aliphatic hydrocarbons having a wide carbon number distribution range of C1 to C30 generated by thermally decomposing the heat-melted hydrocarbon-based plastic without oxygen and without a catalyst, any general distillation form may be used.

[0028] (A) In the step, since the hydrocarbon-based plastic is pyrolyzed without oxygen and without a catalyst, aliphatic hydrocarbons having a wide carbon number distribution ranging from C1 to C30 are produced. Among these, relatively lower aliphatic hydrocarbons having C1 to C15, that is, low-boiling components are separated by distillation and used as part of the pyrolyzate supplied to the (B) step. On the other hand, relatively higher aliphatic hydrocarbons having C16 to C30, that is, high-boiling components are brought into contact with a zeolite having a solid acid amount of 200 μmol / g or less by the NH3-TPD method, and the pyrolyzate produced by catalytic pyrolysis is also used as part of the pyrolysis product supplied to the (B) step. By adding a step of separating the pyrolyzate into high-boiling components and low-boiling components by distillation between the (A) step and the (C) step, the burden on the zeolite having a solid acid amount of 200 μmol / g or less by the NH3-TPD method is reduced, and there is an advantage that deterioration of the zeolite catalyst can be suppressed.

[0029] The (3) step constituting the production method of the present invention is such that by bringing the pyrolysis product into contact with a catalyst containing a zeolite satisfying the above (i) to (iv) characteristics under heating conditions, it is possible to simultaneously produce lower aliphatic hydrocarbons and aromatic hydrocarbons, particularly olefins, paraffins, and aromatic hydrocarbons having 2 to 8 carbon atoms, with high selectivity. The reaction temperature at that time is not particularly limited, and since it becomes a more efficient production method, a range of 350 to 650 °C is preferable, and a range of 500 to 600 °C is more preferable because the selectivity of useful components is high. Also, there is no limitation on the reaction pressure, and for example, it can be operated in a pressure range of about 0.05 MPa to 5 MPa. The supply of the pyrolysis product is not particularly limited as the ratio of the volume of the original pyrolysis product gas to the volume of the catalyst body, and for example, 1 h -1 ~50000 h -1 about a space velocity can be mentioned. At that time, it can also be used as diluted with a single or mixed gas selected from inert gases such as nitrogen, hydrogen, carbon monoxide, and carbon dioxide. Also, there is no limitation on the reaction apparatus at that time, and examples thereof include heating decomposition apparatuses such as a single-screw or twin-screw extrusion melter heated by a heat medium jacket or a heater, and a stirred autoclave.

[0030] And the zeolite contained in the catalyst in step (3) has an average particle diameter (hereinafter sometimes referred to as PD) ≦ 100 nm, and in particular, since it becomes a catalyst with excellent thermal stability, it is desirable that 5 nm ≦ PD ≦ 100 nm. Here, when PD exceeds 100 nm, the conversion efficiency to lower aliphatic hydrocarbons and aromatic hydrocarbons of the pyrolysis products of hydrocarbon-based plastics deteriorates.

[0031] In addition, PD in the present invention is not limited to its measurement method. For example, from photographs of a scanning electron microscope (SEM) or a transmission electron microscope (TEM), 100 or more arbitrary particles are selected and their average diameter is determined. From the external surface area of the zeolite, PD = 6 / S × (1 / (2.29×10 6 )) + 0.18×10 -6 )(S represents the external surface area (m 2 / g)).) And any method such as a method calculated using can be mentioned.

[0032] In addition, the external surface area (S (m 2 / g)) can be obtained from the t-plot method using a general nitrogen adsorption method at liquid nitrogen temperature. For example, when t is the thickness of the adsorption amount, the measurement points in the range of 0.6 to 1 nm for t are linearly approximated, and the external surface area of the zeolite can be obtained from the slope of the obtained regression line.

[0033] And among them, since simple measurement is possible, the method using SEM or TEM is preferred.

[0034] Further, the zeolite is (ii) a 10-membered ring pore zeolite of the MFI type or MEL type. Here, as the MFI type zeolite, an aluminosilicate compound belonging to the structure code MFI defined by the International Zeolite Association can be mentioned, and as the MEL type zeolite, an aluminosilicate compound belonging to the same structure code MEL can be mentioned. Here, when it contains zeolites other than the 10-membered ring pore zeolites of the MFI type or MEL type, the efficiency of the conversion reaction of the pyrolysis products of hydrocarbon-based plastics will be inferior.

[0035] The zeolite is (iii) such that the amount of Bronsted acid on the outer surface (hereinafter sometimes referred to as the amount of B acid) is 0.1 to 10.0 μmol / g, and by having the amount of outer surface B acid within a specific range, it exhibits particularly excellent catalytic performance. Here, when the amount of outer surface B acid is less than 0.1 μmol / g, the production efficiency and catalytic performance will be inferior when converting the pyrolysis products of hydrocarbon-based plastics. On the other hand, when it is greater than 10.0 μmol / g, side reactions and coking are likely to occur on the catalyst surface, and the catalytic performance will be insufficient.

[0036] And in the zeolite, since it is a catalyst excellent in the conversion efficiency of the pyrolysis products of hydrocarbon-based plastics, particularly in the selectivity to lower aliphatic hydrocarbons and aromatic hydrocarbons having 2 to 8 carbon atoms, (iv) those having a B acid amount of 0.01 to 1.0 mmol / g are preferred, and those having a B acid amount of 0.1 to 1.0 mmol / g are more preferred.

[0037] Here, the B acid amount of the zeolite indicates the amount of Bronsted acid sites (hereinafter sometimes referred to as B acid sites), and indicates the acidic OH groups present in the zeolite. Usually, zeolites have B acid sites on their outer surface and in (micro) pores. And those having only a small amount of B acid sites on the outer surface mean that most of the B acid sites are present in the (micro) pores.

[0038] As a method for confirming the amount of Brønsted acid on the outer surface of the zeolite, any method can be used as long as the confirmation can be carried out. For example, it can be confirmed by the adsorption of 2,4-dimethylquinoline having an adsorptivity for Brønsted acid sites. 2,4-Dimethylquinoline has an adsorption property with Brønsted acid sites (acidic OH groups) present in the zeolite (including inside the pores). However, when the (micro) pore diameter of the zeolite is smaller than the 2,4-dimethylquinoline molecule, such as in the MFI type, it cannot penetrate into the (micro) pores and cannot adsorb with the Brønsted acid sites inside the (micro) pores. That is, it will adsorb only with the Brønsted acid sites on the outer surface of the zeolite. Therefore, by determining the adsorption amount of 2,4-dimethylquinoline on the Brønsted acid sites on the outer surface of the MFI type zeolite, the amount of Brønsted acid on the outer surface can be quantified.

[0039] As a more specific method, infrared absorption spectrum measurement is performed at 150 °C on the zeolite that has been subjected to degassing and dehydration treatment at 400 °C for 2 hours as a pretreatment of the zeolite. Then, 2,4-dimethylquinoline gas is introduced into the degassed and dehydrated zeolite and adsorbed for 30 minutes, and excess 2,4-dimethylquinoline is removed by evacuation at 150 °C to prepare 2,4-dimethylquinoline-adsorbed zeolite and perform infrared absorption spectrum measurement at 150 °C. That is, in the difference spectrum of infrared absorption before and after the adsorption of 2,4-dimethylquinoline, by quantifying the difference (decrease) in infrared absorption in the range of 3600 - 3650 cm -1 , the amount of Brønsted acid on the outer surface can be obtained. Note that 2,4-dimethylquinoline also adsorbs to the OH sites on the zeolite surface, but the absorption derived from the O-H stretching vibration of OH is observed at 3700 - 3800 cm -1 . On the other hand, the absorption derived from the O-H stretching vibration of the Brønsted acid sites on the outer surface of the zeolite is observed at 3600 - 3650 cm -1 , and the decrease in the infrared absorption spectrum in the range of 3600 - 3650 cm -1 of the absorption derived from the O-H stretching vibration of the Brønsted acid sites when 2,4-dimethylquinoline is adsorbed indicates that 2,4-dimethylquinoline has adsorbed to the Brønsted acid sites on the outer surface of the zeolite.

[0040] In addition, as a method for measuring the amount of Bronsted acid (Bronsted acid sites present on the outer surface and in the (micro) pores) of the zeolite, any method can be used as long as the measurement can be performed. For example, it can be confirmed by the adsorption of pyridine having adsorptivity for Bronsted acid sites. Pyridine has an adsorption property with Bronsted acid sites (acidic OH groups) present in the zeolite (including inside the pores). When the (micro) pore diameter of the zeolite is larger than that of pyridine, it can also penetrate into the (micro) pores and adsorb with Bronsted acid sites on the outer surface and in the (micro) pores. Therefore, all the amounts of Bronsted acid present in the zeolite, including those present in the pores of the MFI-type zeolite, can be quantified.

[0041] As a more specific method, infrared absorption spectrum measurement is performed at 150 °C on the zeolite that has been subjected to degassing and dehydration treatment at 400 °C for 2 hours as a pretreatment of the zeolite. Then, pyridine gas is introduced into the degassed and dehydrated zeolite and adsorbed for 10 minutes, and excess pyridine is removed by evacuation at 150 °C to prepare pyridine-adsorbed zeolite, and infrared absorption spectrum measurement is performed at 150 °C. That is, in the difference spectrum of infrared absorption before and after pyridine adsorption, the difference (decrease) in infrared absorption in the range of 1515 - 1565 cm -1 By quantifying the difference (decrease) in infrared absorption in the range of, the amount of Bronsted acid including that in the pores can be obtained.

[0042] And the zeolite in the step (3) is preferably a catalyst having excellent conversion efficiency of the pyrolysis product of hydrocarbon-based plastics and selectivity for lower aliphatic hydrocarbons and aromatic hydrocarbons having 2 to 8 carbon atoms. Therefore, it preferably has a small amount of Bronsted acid sites on the outer surface, and most of the Bronsted acid sites are present in the (micro) pores. The Bronsted acid sites present on the outer surface are preferably 1 to 10% of all the Bronsted acid sites. The ratio of the Bronsted acid sites on the outer surface is obtained as the ratio of the amount of Bronsted acid on the outer surface of the zeolite described above to the amount of Bronsted acid present in the zeolite (including inside the pores).

[0043] As a method for producing the zeolite, any method can be used as long as it can produce a zeolite that satisfies the characteristics described in the above (i) to (iv). And, as a method for selectively removing Bronsted acid sites of a specific amount on the outer surface of the zeolite, that is, a zeolite having Bronsted acid sites on the zeolite surface, a method can be mentioned in which part or all of the calcination treatment (heat treatment) when producing a zeolite that satisfies the characteristics of (i) to (ii) is a hydrothermal (steam) treatment, and an ion exchange treatment is added before and after the calcination treatment.

[0044] And, as a method for synthesizing a zeolite that satisfies the characteristics of (i) to (ii), by using a general known method, a zeolite having a framework structure of 10-membered ring pores with PD≤100 nm, MFI type or MEL type can be obtained. Specifically, it can be produced by mixing a compound containing an alkali metal and / or an alkaline earth metal as a cation, an organic structure-directing agent and an aluminosilicate gel, and firing the obtained crystal. Examples of the compound containing an alkali metal and an alkaline earth metal at that time include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, etc., and sodium hydroxide is particularly preferable. Examples of the organic structure-directing agent include tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetraethylammonium hydroxide, etc. Examples of the aluminosilicate gel include amorphous aluminosilicate gel, etc.

[0045] Furthermore, when obtaining a zeolite that satisfies the characteristics of (i) to (iv), ion exchange is performed before firing the crystal obtained as described above, part or all of the firing is a hydrothermal treatment, and then ion exchange is further performed; a method in which ion exchange is performed after firing the crystal obtained as described above to obtain a proton-type zeolite, and then firing is performed in a hydrothermal atmosphere, etc., can be used for production.

[0046] As the firing conditions at that time, the processing temperature is preferably 300 to 900 °C, particularly preferably 400 to 700 °C. The processing time is preferably 5 minutes to 25 hours industrially. As the atmosphere, for example, one or a combination of two or more of nitrogen, air, oxygen, argon, and other inert gases can be mentioned. And, by performing hydrothermal (steam) treatment on a part or all of the firing process, aluminum at the B acid site is desorbed. The processing temperature of the hydrothermal treatment is preferably 400 to 750 °C, particularly preferably 500 to 650 °C. Also, the water vapor concentration is preferably 5 to 100%, particularly preferably 10 to 80%.

[0047] In addition, ion exchange is carried out before and after the firing process, and it may be carried out in multiple divided ion exchanges. Also, examples of ion exchange include ion exchange using acids such as ammonium chloride, hydrochloric acid, and nitric acid, and those using hydrochloric acid and nitric acid are preferred. Also, ion exchange can be substituted with washing with water.

[0048] (3) The zeolite used in the process exhibits high catalytic performance as it is, but since it becomes a catalyst showing even higher coking resistance and catalyst life, (v) it may contain at least one metal selected from sodium, potassium, calcium, silver, and zinc, and it is preferably a metal-containing zeolite with a content rate of 0.05 to 5.0 wt%. Among these metals, since the selectivity for lower aliphatic hydrocarbons and aromatic hydrocarbons having 2 to 8 carbon atoms increases, it is even more preferably a zeolite containing zinc and / or calcium. Also, the introduction method when incorporating the metal is not limited, and for example, any method such as impregnation loading, ion exchange, physical mixing, and vapor deposition is possible.

[0049] When using it as the catalyst in step (3), it is preferable to impart a shape as a molded body because it has excellent handleability and catalyst performance. When imparting a shape, it may be molded by any method. For example, a method of directly compressing zeolite powder into a predetermined shape by compression molding or the like to obtain a molded body, a method of mixing a binder at a predetermined ratio with zeolite, and in some cases, further additives or the like are mixed at a predetermined ratio, and the mixture is molded into a predetermined shape to obtain a molded body, and further, a method of accompanying sintering to obtain a molded body can be mentioned. It is preferable that it is a molded body composed of the zeolite and a binder because it has excellent moldability as a molded body, exhibits high crushing strength, and also has excellent handleability and catalyst life. It is more preferable that it is a molded body composed of the zeolite and silica because it exhibits better catalyst performance. As the silica at that time, any silica belonging to the category called silica may be used, which may have a specific crystal structure or may be amorphous. Further, there are no restrictions on the particle diameter, aggregate diameter, etc. of the silica. Also, the blending ratio of the zeolite and silica is arbitrary. Among them, in particular, since it becomes a zeolite catalyst showing excellent catalyst performance, handleability, and catalyst life, it is preferable that the zeolite:silica = 50 to 95:50 to 5 (weight ratio), and particularly preferably 60 to 90:40 to 10.

[0050] The zeolite catalyst may have any shape, and examples thereof include cylindrical shape, cylindrical shape, triangular prism shape, quadrangular prism shape, pentagonal prism shape, hexagonal prism shape and other polygonal prism shapes, hollow polygonal prism shape, spherical shape, etc. Among them, cylindrical shape and cylindrical shape are preferable because they are excellent in continuous productivity and have high crushing strength. In addition, the size such as its diameter, width, length, etc., and the density such as bulk density and true density can be arbitrarily selected in consideration of filling efficiency, etc. In particular, it can effectively produce lower aliphatic hydrocarbons and aromatic hydrocarbons having 2 to 8 carbon atoms useful as petrochemical products. Therefore, it preferably has a cylindrical shape with a diameter of 1.0 to 10 mm or a cylindrical shape with a thickness of 0.5 to 5.0 mm. The zeolite catalyst in step (3) has high catalytic activity and can extend the catalyst life. Therefore, the amount of solid acid by the NH3-TPD method is preferably 10 to 150, and more preferably 20 to 100.

[0051] In step (3), by contacting the pyrolysis product with a catalyst containing zeolite that satisfies the characteristics of (i) to (iv) under heating conditions, it is possible to highly selectively produce lower hydrocarbons and aromatic hydrocarbons, particularly olefins, paraffins, and aromatic hydrocarbons having 2 to 8 carbon atoms. The reaction temperature at that time is not particularly limited, and the range of 350 to 650 °C is preferable because it is a more efficient production method, and the range of 500 to 600 °C is more preferable because the selectivity of useful components is high. Also, there is no limitation on the reaction pressure, and for example, it can be operated in a pressure range of about 0.05 MPa to 5 MPa. The supply of the pyrolysis product is not particularly limited as the ratio of the volume of the original pyrolysis product gas to the volume of the catalyst body, and for example, 1h -1 ~50000h -1 The space velocity of about can be mentioned. At that time, it can also be used as diluted with a single or mixed gas selected from inert gases such as nitrogen, hydrogen, carbon monoxide, and carbon dioxide.

[0052] In the production method of the present invention, the lower aliphatic hydrocarbons and aromatic hydrocarbons to be produced are preferably olefins, paraffins, and aromatic hydrocarbons having 2 to 8 carbon atoms. For example, paraffins such as ethane, propane, butane, pentane, hexane, heptane, and octane; olefins such as ethylene, propylene, butene, pentene, hexene, heptene, and octene; and aromatic hydrocarbons such as benzene, toluene, xylene, trimethylbenzene, ethylbenzene, and ethyltoluene can be mentioned.

[0053] By the production method of the present invention, the low-molecular-weighting and cyclodehydrogenation reaction of the pyrolysis products of hydrocarbon plastics proceed efficiently, and lower aliphatic hydrocarbons and aromatic hydrocarbons useful as petrochemical products can be produced highly selectively, particularly at a selectivity of 60% or more. In addition, since each component of olefins, paraffins, and aromatic hydrocarbons having 2 to 8 carbon atoms is produced in a well-balanced manner, it becomes possible to perform efficient combined operation with an existing plant without installing a new distillation column. Specifically, since the distillation columns of each component of the ethylene plant can be fully utilized, the ethylene plant can be operated efficiently without excessively reducing the operating rate of the naphtha cracker.

Effects of the Invention

[0054] The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons of the present invention is a production method that can produce paraffins, olefins, and aromatic hydrocarbons having 2 to 8 carbon atoms, which are useful as petrochemical products, in high yields by passing through a specific process using two specific zeolite catalysts when simultaneously producing lower hydrocarbons and aromatic hydrocarbons from the pyrolysis products of hydrocarbon plastics, and moreover, has excellent catalyst life, so it is expected to have industrial utility.

Brief Description of the Drawings

[0055]

Figure 1

Figure 2

Figure 3

Examples

[0056] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0057] ~Measurement of the amount of solid acid by NH3-TPD method~ The measurement of the amount of acid was carried out by a method according to the ammonia-TPD method (measurement of solid acid properties by ammonia temperature-programmed desorption method, see Catalyst, vol. 42, p. 218 (2000)). The apparatus used was a catalyst analyzer (manufactured by Microtrac BEL Corporation, trade name: BELCATII). After pretreatment at 500 °C for 1 hour under a helium flow, ammonia was adsorbed at 100 °C for 30 minutes. Then, under a helium flow containing water vapor by passing through a bubbler, it was treated at 125 °C for 60 minutes to remove ammonia adsorbed at weak acid sites. After that, it was purged at 100 °C under a helium flow, and then the temperature was raised at 10 °C / min under a helium flow to measure the temperature-programmed desorption amount. A quadrupole mass spectrometer (trade name: BELMASS, manufactured by Microtrac BEL Corporation) was used as the detector. The peak derived from the acid site near the desorption temperature of 370 °C in the obtained temperature-programmed desorption curve was fitted with a Gaussian function, and the amount of acid was obtained by determining the ammonia desorption amount from the area.

[0058] ~Measurement of average particle diameter (PD)~ The average particle size was measured by a transmission electron microscope (hereinafter sometimes referred to as TEM) and a scanning electron microscope (hereinafter sometimes referred to as SEM). For TEM, a transmission electron microscope (manufactured by JEOL Ltd., trade name: JEM-2100, acceleration voltage 200 kV, observation magnification 30,000 times) was used. A sample lightly pulverized in a mortar was ultrasonically dispersed in acetone, dropped onto a plastic support film, and air-dried to obtain a sample for microscopy, and a photograph was taken. For each primary particle in the photograph, the longest diameter and the average of the diameters in the direction perpendicular to the midpoint were measured, and the average of a total of 300 particles was taken as the average particle size.

[0059] For SEM, a scanning electron microscope (manufactured by KEYENCE CORPORATION, trade name: VE-9800, acceleration voltage 20 kV, observation magnification 2000 times) was used. A sample lightly pulverized in a mortar was placed on a sample stage, and the sample with gold vapor deposition was used as a sample for microscopy, and a photograph was taken. The length of one side of 150 particles in the photograph was measured, and the average value was taken as the average crystal size.

[0060] ~Measurement of Powder X-ray Diffraction~ Using an X-ray diffractometer (manufactured by Spectris, trade name: X’pert PRO MPD), CuKα1 was used with a tube voltage of 45 kV and a tube current of 40 mA, and the measurement was carried out in the air. The range of 0.04 to 5 degrees was analyzed at 0.08 degrees / step and 200 seconds / step. Also, the background corrected by the absorption rate of the direct beam was removed.

[0061] The crystal structure was identified by visually checking the presence or absence of peaks. As another method, a peak search program may be used. As the peak search program, a general program can be used. For example, when the measurement results with the horizontal axis being 2θ (degrees) and the vertical axis being intensity (a.u.) are smoothed with the Savitzky & Golay formula and the Sliding Polynomial filter and then second-order differentiation is performed, if there are three or more consecutive negative values, it can be determined that a peak exists.

[0062] ~2,4-Dimethylquinoline Adsorption Infrared Absorption Spectroscopy Measurement (Amount of Bronsted Acid on the Outer Surface)~ The measurement of infrared absorption spectroscopy was carried out by the transmission method using an FT-IR measurement device (trade name: FT / IR-6700, manufactured by JASCO Corporation). A MCT detector was used, and spectra were obtained with 256 accumulations. The sample was formed into a disk with a diameter of 13 mm and then placed on a disk holder in a quartz vacuum degassing cell, installed perpendicular to the infrared light path. As a pretreatment of the sample, the temperature was raised to 400 °C at 10 °C / min under vacuum evacuation and held for 2 hours. After cooling to 150 °C, the infrared absorption spectrum before the adsorption of 2,4-dimethylquinoline was measured. 2,4-Dimethylquinoline gas was introduced and adsorbed for 30 minutes, and after vacuum evacuation at 150 °C for 1 hour, the infrared absorption spectrum after the adsorption of 2,4-dimethylquinoline was measured. The difference between the infrared absorption spectrum after the adsorption of 2,4-dimethylquinoline and the spectrum before adsorption was taken to measure the change in infrared absorption due to adsorption. Among these difference spectra, the peak around 3600 cm -1 is the peak of the absorption spectrum of 2,4-dimethylquinoline adsorbed on Bronsted acid. After determining this area intensity, according to the Lambert-Beer's law, the amount of Bronsted acid (μmol / mg) = A·S / (W·ε) (where A is the peak area intensity (cm -1 ) of the target peak, S is the sample cross-sectional area (cm 2 ), W is the sample weight (mg), and ε is the integrated absorption coefficient, which is 3.7 cm·μmol -1 respectively), the amount of Bronsted acid on the outer surface was determined.

[0063] ~ Pyridine adsorption infrared absorption spectroscopy measurement (total amount of Bronsted acid) ~ In the above 2,4-dimethylquinoline adsorption infrared absorption spectroscopy measurement, only the point where pyridine gas was introduced and adsorbed for 10 minutes was changed, and the measurement was carried out with the same apparatus and the same method.

[0064] However, the peak around 1545 cm -1 in the difference spectrum was used as the peak of the absorption spectrum of pyridine adsorbed on Bronsted acid, and with the integrated absorption coefficient of 1.67 cm·μmol -1 , the total amount of Bronsted acid was determined from the Lambert-Beer's law.

[0065] ~External surface B acid ratio~ The external surface B acid ratio was defined as the ratio of the external surface B acid amount to the total B acid amount.

[0066] ~Measurement of SiO2 / Al2O3 molar ratio and metal introduction amount~ The SiO2 / Al2O3 molar ratio of the zeolite and the introduction amount of the transition metal were measured and determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) using an ICP device (trade name: OPTIMA3300DV, manufactured by PerkinElmer) after dissolving the zeolite in an aqueous mixed solution of hydrofluoric acid and nitric acid.

[0067] ~Catalyst activity test method serving as an index of the catalyst life including the zeolite used in step (3)~ After conducting an experiment using hydrocarbon-based plastic as a raw material and converting it into lower aliphatic hydrocarbons and aromatic hydrocarbons, in order to grasp the catalytic performance of the zeolite in step (3), a catalyst activity test was conducted using the following C4 fraction. The conversion rate of the C4 fraction 1 hour after the start of the reaction was used as an index of the catalyst life.

[0068] (Catalyst reaction conditions in the catalyst activity test) C4 fraction: isobutane 2 Nml / min, normal butane 5 Nml / min, trans-2-butene 8 Nml / min, 1-butene 15 Nml / min, isobutene 3 Nml / min, propane 7 Nml / min, propylene 2 Nml / min Diluent gas; nitrogen 42 Nml / min. Reaction temperature: 530 °C. Reaction time: 1 hour.

[0069] Catalyst Preparation Example 1 The proton-type MFI zeolite powder (manufactured by Tosoh Corporation, trade name: HSZ-840HOA) was calcined at 550 °C for 1 hour under air, and then treated with 600 °C and 30% steam. Subsequently, it was calcined at 550 °C for 2 hours under air to obtain a powder.

[0070] Catalyst Preparation Example 2 The zeolite powder obtained by Catalyst Preparation Example 1 was immersed in distilled water to prepare a suspension. An aqueous solution of 0.2 mol / L sodium nitrate was gradually added to this suspension at room temperature, and sodium ion exchange was carried out by stirring at 80 °C for 2 hours. After cooling to room temperature, filtration, washing with distilled water, and drying were sequentially performed, and then calcination was carried out at 550 °C in air for 4 hours to obtain a zeolite powder partially exchanged with sodium ions.

[0071] To 100 parts by weight of this powder, 40 parts by weight of silica (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex N-30G), 5 parts by weight of cellulose, and 40 parts by weight of pure water were added and kneaded. Then, the kneaded material was made into a columnar molded body with a diameter of 1.5 mm and a length of 1.0 to 7.0 mm (average length 3.5 mm). This was dried at 100 °C overnight. The dried molded body was calcined at 600 °C for 2 hours under air circulation to obtain a molded body.

[0072] Catalyst Preparation Example 3 To 100 parts by weight of proton-type MFI zeolite powder (manufactured by Tosoh Corporation, trade name: HSZ-840HOA), 40 parts by weight of silica (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex N-30G), 5 parts by weight of cellulose, and 40 parts by weight of pure water were added and kneaded. Then, the kneaded material was made into a columnar molded body with a diameter of 1.5 mm and a length of 1.0 to 7.0 mm (average length 3.5 mm). This was dried at 100 °C overnight. The dried molded body was calcined at 600 °C for 2 hours under air circulation to obtain a molded body.

[0073] Catalyst Preparation Example 4 100 g of the molded body obtained by Catalyst Preparation Example 3 was immersed in distilled water. It was immersed using a 0.12 mol / L aqueous calcium hydroxide solution. The molded body was filtered off, washed with water, and then immersed again in a 0.2 mol / L aqueous sodium nitrate solution. After drying overnight at 110 °C, calcination was carried out at 550 °C for 5 hours under air circulation to obtain a zeolite (molded body) in which calcium ions and sodium ions were partially exchanged.

[0074] Catalyst Preparation Example 5 An amorphous aluminosilicate gel was added to an aqueous solution of tetrapropylammonium hydroxide and sodium hydroxide and suspended. MFI-type zeolite was added as seed crystals to the resulting suspension to obtain a raw material composition. The addition amount of the seed crystals at that time was 0.7% by weight based on the weights of Al2O3 and SiO2 in the raw material composition. The composition of the raw material composition is as follows. SiO2 / Al2O3 molar ratio = 48, TPA / Si molar ratio = 0.05, Na / Si molar ratio = 0.16, OH / Si molar ratio = 0.21, H2O / Si molar ratio = 10.

[0075] The obtained raw material composition was sealed in a stainless steel autoclave and crystallized for 4 days with stirring at 115 °C to obtain a slurry-like mixture. After solid-liquid separation of the slurry-like mixture after crystallization with a centrifugal sedimentation machine, the solid particles were washed with a sufficient amount of pure water and dried at 110 °C to obtain a dry powder.

[0076] The obtained dry powder was dispersed in 1 mol / L hydrochloric acid at room temperature, filtered, then the solid particles were washed with a sufficient amount of pure water, filtered again, and dried at 100 °C overnight. After calcination at 550 °C for 1 hour under air, it was treated with 30% steam at 600 °C for 2 hours.

[0077] The obtained powder was dispersed in 1 mol / L hydrochloric acid at room temperature, filtered, then the solid particles were washed with a sufficient amount of pure water, filtered again, and zeolite was obtained.

[0078] To 100 parts by weight of the zeolite prepared above, 25 parts by weight of silica (manufactured by Nissan Chemical Industries, Ltd., trade name: Snowtex N-30G), 5 parts by weight of cellulose, and 40 parts by weight of pure water were added and kneaded. Then, the kneaded product was made into a columnar molded body with a diameter of 1.5 mm and a length of 1.0 to 7.0 mm (average length 3.5 mm). This was dried at 100 °C overnight. The dried molded body was calcined at 600 °C for 2 hours under air flow to obtain a molded body.

[0079] Catalyst Preparation Example 6 100 g of the MFI-type zeolite formed body obtained by Catalyst Preparation Example 5 was immersed in 109.9 g of a 0.75 mol / L aqueous zinc acetate solution for 30 minutes. After filtering off the formed body, it was dried overnight at 110 °C and then calcined at 550 °C for 5 hours under air circulation to obtain a zeolite (formed body) partially containing zinc ions.

[0080] Example 1 An apparatus was used in which a stainless steel autoclave (internal volume 200 ml) for performing the (1) step of melting a hydrocarbon-based plastic and the (2) step of pyrolysis was connected to a stainless steel reaction tube (inner diameter 16 mm, length 600 mm) for performing the (3) step of converting the pyrolysis product into lower hydrocarbons. Here, the middle part of the stainless steel reaction tube was filled with a formed body of the zeolite catalyst, and heat pretreatment was performed at 530 °C under a dry air flow.

[0081] Into the stainless steel autoclave, 5 g of high-density polyethylene (HDPE) that became waste during the production process of a low-pressure polyethylene production facility and the zeolite catalyst (powder) prepared in Catalyst Preparation Example 1 were put and replaced with nitrogen. By slowly raising the temperature to 180 °C, HDPE was brought into a molten state, and then the temperature was raised to 450 °C under a nitrogen gas flow (40 ml / min), and heating and catalytic decomposition were performed to obtain the hydrocarbon produced as the pyrolysis product. The pyrolysis product was fed into the stainless steel reaction tube by nitrogen gas and reacted in contact with the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 5 (catalyst weight: 3.8 g, flowing gas: nitrogen 40 ml / min, reaction temperature: 585 °C, reaction time: 24 hours). Note that a ceramic tubular furnace was used for temperature control of the stainless steel reaction tube.

[0082] The reaction outlet gas and reaction solution were collected, and the gas components and liquid components were analyzed separately using a gas chromatograph. The gas components were analyzed using a gas chromatograph (manufactured by Shimadzu Corporation, model name: GC-1700) equipped with a TCD detector and having a packing material (manufactured by Waters Corporation, product name: Porapak Q or manufactured by GL Sciences Inc., product name: MS-5A). The liquid components were analyzed using a gas chromatograph (manufactured by Shimadzu Corporation, model name: GC-2015) equipped with an FID detector and having a capillary column (manufactured by GL Sciences Inc., product name: TC-1) as a separation column.

[0083] The results are shown in Table 1. Useful components of lower aliphatic hydrocarbons and aromatic hydrocarbons having 2 to 8 carbon atoms were obtained in high yields. Further, even after the completion of the reaction, the zeolite catalyst prepared in Catalyst Preparation Example 5 maintained high catalytic performance, enabling stable production and being excellent in coke resistance.

[0084] Example 2 An apparatus in which a stainless steel autoclave (internal volume: 200 ml) for performing the (1) step of melting a hydrocarbon-based plastic and the (2) step of pyrolysis and a stainless steel reaction tube (inner diameter: 16 mm, length: 600 mm) for performing the (3) step of converting the pyrolysis product into lower hydrocarbons were connected was used. Here, the stainless steel reaction tube was filled with the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 2 in the front stage and the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 6 in the rear stage, and heat pretreatment was performed at 530 °C under a dry air flow.

[0085] A stainless steel autoclave was charged with high-density polyethylene (HDPE) that had become waste during the manufacturing process of low-pressure polyethylene production equipment and purged with nitrogen. The temperature was slowly raised to 180 °C to melt the HDPE, and then it was heated to 450 °C under a nitrogen gas flow (40 ml / min) to perform pyrolysis, resulting in pyrolysis products that were hydrocarbon mixtures. The pyrolysis products were fed into a stainless steel reaction tube by nitrogen gas and reacted by contacting with two types of zeolite catalysts (formed bodies) (catalyst weight: 3.8 g each, flowing gas: nitrogen 40 ml / min, reaction temperature: 530 °C, reaction time: 24 hours).

[0086] The product was analyzed in the same manner as in Example 1, and the results are shown in Table 1.

[0087] Example 3 A stainless steel autoclave was charged with high-density polyethylene (LDPE) that had become waste during the manufacturing process of high-pressure polyethylene production equipment and purged with nitrogen. The temperature was slowly raised to 180 °C to melt the LDPE, and then it was heated to 450 °C under a nitrogen gas flow (40 ml / min) to perform pyrolysis. As pyrolysis products, the gas components and liquid components at normal temperature and pressure were collected separately.

[0088] Distillation of the liquid component (pressure 2.6 kPa, reflux ratio 20) was performed using a packed column distillation column with 35 theoretical plates equipped with a mantle heater type distillation kettle, thermometer, reflux valve, and effluent receiver (manufactured by Shibata Scientific, trade name: HP-1000), and the distillation was terminated when the component with a top temperature of 150 °C flowed out.

[0089] A fixed-bed gas-phase flow-type reactor having a stainless steel reaction tube (inner diameter 16 mm, length 600 mm) for converting pyrolysis products into lower hydrocarbons was used. The stainless steel reaction tube was filled with the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 2 in the front stage and the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 5 in the rear stage, and heat pretreatment was performed at 530 °C under a dry air flow.

[0090] The liquid components collected in the effluent receiver were fed using a liquid transfer pump, and the gas components were analyzed using a gas chromatograph. Based on the analysis results, simulated gas components were prepared using reagents, and using a mass flow controller, the liquid components and gas components were fed into a stainless steel reaction tube and contacted with a zeolite catalyst (formed body) to conduct a reaction (catalyst weight: 3.8 g each, flowing gas: nitrogen 40 ml / min, reaction temperature: 530 °C, reaction time: 24 hours).

[0091] The analysis of the product was carried out in the same manner as in Example 1, and the results are shown in Table 1.

[0092] Comparative Example 1 Except for not using the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 2 and using the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 3 instead of the zeolite catalyst (formed body) prepared in Catalyst Preparation Example 6, the pyrolysis of hydrocarbon-based plastics and the reaction evaluation using a zeolite catalyst were carried out in the same manner as in Example 2. The results are shown in Table 1.

[0093]

Table 1

Industrial Applicability

[0094] The method for producing lower aliphatic hydrocarbons and aromatic hydrocarbons of the present invention can highly selectively convert hydrocarbon-based plastics, particularly pyrolysis products of waste plastics, into paraffins, olefins, and aromatic hydrocarbons having 2 to 8 carbon atoms, which are useful as petrochemical products, and its industrial value as a production method is extremely high.

Claims

1. A method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons, characterized by passing through at least the following steps (1) to (3) when producing lower hydrocarbons and aromatic hydrocarbons from the pyrolysis products of hydrocarbon-based plastics. Step (1); a step of heating and melting the hydrocarbon-based plastic. (2) Step; pyrolysis in the presence of zeolite in which the acid amount (NH ３ -TPD method for solid acid amount) is 200 μmol / g or less based on the high-temperature desorption amount in the ammonia temperature-programmed desorption spectrum, to obtain a pyrolysis product. Step (3); a step of contacting the pyrolysis product with a catalyst containing zeolite satisfying the following characteristics (i) to (iv) under heating conditions to simultaneously produce lower aliphatic hydrocarbons and aromatic hydrocarbons. (i) The average particle diameter is 100 nm or less. (ii) A 10-membered ring microporous zeolite of MFI type or MEL type. (iii) The amount of Bronsted acid on the outer surface is 0.1 to 10.0 μmol / g. (iv) The total amount of Bronsted acid is 0.01 to 1.0 mmol / g.

2. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to Claim 1, characterized in that the zeolite in step (2) is a proton-type aluminosilicate.

3. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to Claim 1 or 2, characterized in that the zeolite in step (2) is a proton-type aluminosilicate and contains at least one metal selected from metals belonging to Group IA and IIA of the periodic table.

4. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to any one of Claims 1 to 3, characterized in that the zeolite in step (2) is a proton-type aluminosilicate and is a zeolite in which part or all of the surface OH groups have been silylated.

5. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to any one of Claims 1 to 4, characterized in that step (2) passes through at least the following steps (a) and (b). Step (a); a first decomposition step of pyrolyzing the heated and melted hydrocarbon-based plastic without oxygen and without a catalyst. Step (b); a second decomposition step of contacting and pyrolyzing with zeolite after step (a) to obtain a pyrolysis product.

6. There is a step of separating the pyrolyzate into high-boiling components and low-boiling components by distillation between the step (a) and the step (b), the step (b) is one that contacts and pyrolyzes the high-boiling components and zeolite, and further as the step (d), it passes through a step of mixing the low-boiling components of the step (a) and the pyrolyzate of the step (b) to obtain a pyrolysis product. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to claim 5, characterized in that.

7. The zeolite in the step (3) contains at least one or more metals selected from sodium, potassium, calcium, silver, and zinc, and the content rate thereof is 0.05 to 5.0 wt%. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to any one of claims 1 to 6, characterized in that.

8. The hydrocarbon-based plastic is at least one or more selected from polyethylene, polypropylene, ethylene-propylene rubber, and polystyrene. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to any one of claims 1 to 7, characterized in that.

9. The hydrocarbon-based plastic is waste plastic that has been used and / or waste products generated during the production and processing of hydrocarbon-based plastics. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to any one of claims 1 to 8, characterized in that.

10. The total selectivity of lower aliphatic hydrocarbons and aromatic hydrocarbons is 60% or more. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to any one of claims 1 to 9, characterized in that.

11. The lower aliphatic hydrocarbon is any one or more belonging to olefins having 2 to 8 carbon atoms and paraffins having 2 to 8 carbon atoms, and the aromatic hydrocarbon is any one or more belonging to aromatic hydrocarbons having 6 to 8 carbon atoms. The method for simultaneously producing lower aliphatic hydrocarbons and aromatic hydrocarbons according to any one of claims 1 to 10, characterized in that.

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