Hydrocarbon adsorbent and method for adsorbing hydrocarbons

Abstract

The objective is to provide a hydrocarbon adsorbent with a high hydrocarbon desorption initiation temperature, and to provide at least one of the following: a hydrocarbon adsorbent and a hydrocarbon adsorption method using the hydrocarbon adsorbent. [Solution] A hydrocarbon adsorbent comprising a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores.

Description

[Technical Field]

[0001] This disclosure relates to hydrocarbon adsorbents and methods for adsorbing hydrocarbons. [Background technology]

[0002] Exhaust gases emitted from internal combustion engines used in mobile vehicles such as automobiles and ships contain a large amount of hydrocarbons. Hydrocarbons emitted from internal combustion engines are purified by a three-way catalytic converter. A temperature environment of 200°C or higher is required for the three-way catalytic converter to function. Therefore, in temperature ranges where the three-way catalytic converter does not function, such as during a so-called cold start, hydrocarbons are adsorbed onto a hydrocarbon adsorbent, and then released from the adsorbent when the temperature range in which the three-way catalytic converter begins to function is reached, thereby decomposing and purifying the hydrocarbons with the three-way catalytic converter. Compositions containing zeolite are generally used as hydrocarbon adsorbents, and the higher the desorption initiation temperature of the hydrocarbon in the composition, the more active the three-way catalytic converter can be in when releasing hydrocarbons. Compositions with a high hydrocarbon desorption initiation temperature are desired because they work advantageously for hydrocarbon purification.

[0003] Patent Document 1 proposes a composition containing a zeolite that includes at least one ion with an elemental electronegativity of 1.40 or higher as a composition with a high hydrocarbon desorption initiation temperature. Although Patent Document 1 provides a composition with a high desorption initiation temperature, it requires the use of a precious metal as a catalyst, and the hydrocarbon adsorbent located before the three-way catalyst is exposed to higher temperatures. Therefore, the composition in Patent Document 1 does not have sufficient heat resistance to be practical as a hydrocarbon adsorbent for purifying hydrocarbons emitted from internal combustion engines, and is also disadvantageous in terms of cost.

[0004] Patent document 2 proposes a hydrocarbon adsorbent consisting of a zeolite containing an alkali metal. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-005020 [Patent Document 2] Japanese Patent Publication No. 2001-293368 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The hydrocarbon adsorbent described in Patent Document 2 had the problem that the desorption initiation temperature of hydrocarbons was not sufficiently high. The object of this disclosure is to provide a hydrocarbon adsorbent with a high desorption initiation temperature of hydrocarbons, and to provide at least one of the above: a hydrocarbon adsorbent and a method for adsorbing hydrocarbons using the hydrocarbon adsorbent. [Means for solving the problem]

[0007] The inventors investigated the hydrocarbon adsorption properties of compositions containing zeolite. As a result, they found that hydrocarbon adsorbents containing zeolite having the following pore structure exhibit a high hydrocarbon desorption initiation temperature.

[0008] In other words, the present invention is as described in the claims, and the gist of this disclosure is as follows: [1] A hydrocarbon adsorbent comprising a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores. [2] The hydrocarbon adsorbent according to [1] above, wherein the three-dimensional pore is a three-dimensional pore consisting of two or more pores selected from the group consisting of 10-membered ring pores, 12-membered ring pores, and 14-membered ring pores. [3] The hydrocarbon adsorbent according to [1] above, wherein the three-dimensional pores consist of 10-membered ring pores and 12-membered ring pores. [4] A hydrocarbon adsorbent according to any one of the above [1] to [3], which contains a metal. [5] The hydrocarbon adsorbent according to [4] above, wherein the metal is at least one of rubidium and cesium. [6] The hydrocarbon adsorbent according to [4] or [5] above, wherein the main peak in the MAS NMR spectrum for the metal is located between -250 ppm and -130 ppm. [7] The hydrocarbon adsorbent according to [4] to [6] above, wherein the main peak in the MAS NMR spectrum for the metal is located between -250 ppm and -150 ppm. [8] 133 A hydrocarbon adsorbent according to [4] to [7] above, wherein the main peak in the Cs MAS NMR spectrum is located between -300 ppm and -130 ppm. [9] 133 A hydrocarbon adsorbent according to [4] to [8] above, wherein the main peak in the Cs MAS NMR spectrum is located between -300 ppm and -130 ppm.

[10] The hydrocarbon adsorbent according to any one of [1] to [9] above, wherein the zeolite is a zeolite having a molar ratio of silica to alumina (SiO2 / Al2O3 ratio) of 2 or more and 200 or less.

[11] The hydrocarbon adsorbent according to any one of [1] to

[10] above, wherein the zeolite is a zeolite having at least one structure selected from an MSE structure and a CON structure.

[12] A method for adsorbing hydrocarbons, characterized by contacting a hydrocarbon-containing fluid with a hydrocarbon adsorbent described in any of [1] to

[11] above. [Effects of the Invention]

[0009] This disclosure aims to achieve at least one of the following objectives: to provide a hydrocarbon adsorbent with a high hydrocarbon desorption initiation temperature when the SiO2 / Al2O3 ratio is similar; and to provide a method for adsorbing hydrocarbons using the hydrocarbon adsorbent. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows the 133Cs MAS NMR spectrum and waveform separation results for Example 1. [Figure 2]It is a diagram showing the 133Cs MAS NMR spectrum and the waveform separation result of Comparative Example 3.

Mode for Carrying Out the Invention

[0011] Hereinafter, an example of an embodiment of the hydrocarbon adsorbent of the present disclosure will be shown and described.

[0012] The hydrocarbon adsorbent of this embodiment is characterized by including a zeolite having three-dimensional pores composed of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores.

[0013] In this embodiment, zeolite is a compound having a regular structure in which framework atoms (hereinafter, also referred to as "T atoms") are bonded via oxygen (O), and the T atoms are a compound composed of at least any one of metal atoms, metalloid atoms, and other atoms. Examples of metal atoms include one or more selected from the group of iron (Fe), aluminum (Al), gallium (Ga), tin (Sn), and titanium (Ti), and other transition metal elements. Examples of metalloid atoms include one or more selected from the group of boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te). An example of other atoms is phosphorus (P). Specific zeolites include one or more selected from the group of aluminosilicate, ferrosilicate, and gallosilicate, such as metallosilicates in which T atoms are composed of metal atoms and silicon, and metal phosphates such as at least any one of aluminophosphate (AlPO) and silicoaluminophosphate (SAPO). However, it is preferable that the zeolite contained in the hydrocarbon adsorbent of this embodiment does not contain phosphorus as a T atom.

[0014] The zeolite contained in the hydrocarbon adsorbent of this embodiment is preferably a metallosilicate, more preferably a crystalline aluminosilicate. The crystalline aluminosilicate is a compound having a crystal structure composed of a network repetition of aluminum (Al) and silicon (Si) via oxygen (O). The crystalline aluminosilicate may have a structure in which at least a part of at least one of the aluminum and silicon of the T atoms is substituted with at least one of metal atoms and metalloid atoms of aluminum and silicon.

[0015] The framework structure of the zeolite (used interchangeably with the crystal structure and hereinafter also referred to as the "zeolite structure") is a framework structure specified by a structure code determined by the Structure Commission of the International Zeolite Association (hereinafter simply referred to as the "structure code"), and is identified by comparing the XRD pattern of each zeolite structure described in Collection of simulated XRD powder patterns for zeolites, Fifth revised edition (2007) (hereinafter also referred to as the "reference pattern") with the XRD pattern of the target zeolite.

[0016] In this embodiment, examples of the XRD pattern include those obtained from XRD measurement under the following conditions.

[0017] Accelerating current·voltage: 40 mA·40 kV X-ray source: CuKα ray (λ = 1.5405 Å) Measurement mode: Continuous scan Scan condition: 40° / min Measurement range: 2θ = 3° to 43° Detector: Semiconductor detector In this embodiment, a zeolite having a zeolite structure indicated by a specific structural code is also referred to as a "~-type zeolite." For example, CON structure (or CON type) means a zeolite structure specified by the structural code "CON," and CON-type zeolite is a zeolite having a zeolite structure specified by the structural code "CON."

[0018] The pores of zeolites are formed by a cyclic structure consisting of T atoms and oxygen atoms bonded to them (hereinafter also referred to as "skeletal oxygen"). The pore diameter of a zeolite is determined by the number of skeletal oxygen atoms bonded to the T atoms that form the pore. In this embodiment, a ring surrounded by 6 skeletal oxygen atoms is called a 6-membered oxygen ring, a ring surrounded by 8 skeletal oxygen atoms is called an 8-membered oxygen ring, a ring surrounded by 10 skeletal oxygen atoms is called a 10-membered oxygen ring, a ring surrounded by 12 skeletal oxygen atoms is called a 12-membered oxygen ring, a ring surrounded by 14 skeletal oxygen atoms is called a 14-membered oxygen ring, a ring surrounded by 18 skeletal oxygen atoms is called an 18-membered oxygen ring, and so on. A ring surrounded by n skeletal oxygen atoms is called an "n-membered oxygen ring" or simply an "n-membered ring," and the pores formed by these n-membered oxygen rings are called "n-membered ring pores" (where n is an integer of 3 or more). The pore diameter tends to increase as the number of skeletal oxygen atoms in an n-membered ring pore increases.

[0019] The pore dimensions of zeolites are generally known to be one-dimensional pores (more specifically, tunnel-type one-dimensional pores or cage-type one-dimensional pores), two-dimensional pores, and three-dimensional pores. In this embodiment, the pore dimensions can be classified in the same way as the dimensions classified by Channel dimensionality (Sorption) as defined by IZA, where dimension 1 corresponds to one-dimensional pores, dimension 2 to two-dimensional pores, and dimension 3 to three-dimensional pores. The pore dimensions can be confirmed, for example, on the IZA homepage (https: / / asia.iza-structure.org / IZA-SC / search_cs.html). Specifically, the zeolite having one-dimensional pores in this embodiment is a zeolite in which pores are formed only in one-dimensional directions, and these pores do not have a structure that intersects with other pores. The zeolite having one-dimensional pores is characterized by having a structure in which the pore spaces formed by the above pores are connected in a straight line. Examples of such zeolite structures include one or more selected from the group consisting of MOR structure, LTL structure, DON structure, CFI structure, and AFI structure. Two-dimensional pores refer to a pore structure in which one-dimensional pores are connected in different directions, such as horizontal holes, and are characterized by having a structure in which the pore space is connected in a planar manner. Examples of zeolite structures having two-dimensional pores include one or more selected from the group consisting of NES structure, MWW structure, and FER structure. Three-dimensional pores refer to a pore structure in which two-dimensional pores are further connected by other holes (for example, holes in different directions from the two pores that form the two-dimensional pore, such as vertical holes), and are characterized by having a structure in which the pore space is connected in three dimensions: up, down, left, right, front, and back. Examples of zeolite structures having three-dimensional pores include one or more selected from the group consisting of FAU structure, *BEA structure, MFI structure, CON structure, MSE structure, IWR structure, BEC structure, BOG structure, BSV structure, DFO structure, EMT structure, IMF structure, IRR structure, ISV structure, ITG structure, ITT structure, IWS structure, JSR structure, JST structure, MEL structure, POS structure, SAO structure, SOV structure, UWY structure, *-ITN structure, and *SFV structure.In other words, zeolites with one-dimensional pores are zeolites with linear pores, zeolites with two-dimensional pores are zeolites with planar pores, and zeolites with three-dimensional pores are zeolites with three-dimensional pores.

[0020] Note that some classifications of pore dimensions in IZA are based on pores with more than 6-membered rings (Open Pore > 6 ring) (Channel dimensionality (topological)). The pore dimensions in this embodiment may differ from the topological classification of pore dimensions.

[0021] Examples of zeolites having three-dimensional pores (hereinafter also referred to as "three-dimensional pore zeolites") include one or more selected from the group consisting of FAU-type zeolites, *BEA-type zeolites, MSE-type zeolites, and CON-type zeolites. The zeolite contained in the hydrocarbon adsorbent of this embodiment is characterized by being a zeolite having three-dimensional pores consisting of two or more pores selected from the group consisting of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores. That is, the zeolite in the hydrocarbon adsorbent of this embodiment does not include zeolites having three-dimensional pores consisting only of 10-membered rings, three-dimensional pore zeolites consisting only of 12-membered rings, or zeolites having three-dimensional pores consisting only of 10-membered rings, 12-membered ring pores, 14-membered ring pores, or 18-membered ring pores. For example, the FAU structure, *BEA structure, or EMT structure are zeolite structures having a three-dimensional pore consisting of three 12-membered rings (12-12-12-membered rings), and are different from the zeolite structure of the zeolite contained in the hydrocarbon adsorbent of this embodiment. On the other hand, for example, a zeolite structure having a three-dimensional pore consisting of one 12-membered ring and two 10-membered rings (12-10-10-membered rings) (CON structure), and a zeolite structure having a three-dimensional pore formed by one 12-membered ring and two 10-membered rings (12-10-10-membered rings) (IWR structure) are examples of the zeolite structures of the zeolite contained in the hydrocarbon adsorbent of this embodiment. Thus, the zeolite in the hydrocarbon adsorbent of this embodiment is a three-dimensional pore zeolite having two or more pores with different numbers of member rings, selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores. Such zeolites are not particularly limited, but examples include one or more selected from the group consisting of MSE type zeolite, CON type zeolite, IWR type zeolite, *SFV type zeolite, BOG type zeolite, IRR type zeolite, ITG type zeolite, ITT type zeolite, POS type zeolite, UWY type zeolite, and *-ITN type zeolite, and it is preferable that at least one of MSE type zeolite and CON type zeolite is used.In another embodiment, the zeolite contained in the hydrocarbon adsorbent of this embodiment may be any zeolite containing one or more zeolite structures selected from the group consisting of MSE structure, CON structure, IWR structure, *SFV structure, BOG structure, IRR structure, ITG structure, ITT structure, POS structure, UWY structure, and *-ITN structure, or it may be a zeolite containing these zeolite structures and other zeolite structures, a so-called intercrystalline structure. Examples of intercrystalline structures include zeolites having a structure in which a zeolite structure having at least one of one-dimensional pores and two-dimensional pores is stacked with a zeolite structure having three-dimensional pores. It is believed that having such complex pore shapes allows water and hydrocarbons to move through different diffusion paths, and only small molecules of water can desorb from narrow diffusion paths, resulting in competitive adsorption between hydrocarbons and water being more favorable to hydrocarbons, and thus the desorption initiation temperature of hydrocarbons is further increased.

[0022] Furthermore, the zeolite contained in the hydrocarbon adsorbent of this embodiment is preferably a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, and 14-membered ring pores, and more preferably a zeolite having three-dimensional pores consisting of 10-membered ring pores and 12-membered ring pores, in terms of excellent hydrocarbon adsorption performance.

[0023] An example of a zeolite included in the hydrocarbon adsorbent of this embodiment is at least one of MSE-type zeolite and CON-type zeolite. MES-type zeolite and CON-type zeolite are zeolites having a zeolite structure with three-dimensional pores consisting of 12-membered ring pores and 10-membered ring pores, respectively.

[0024] The hydrocarbon adsorbent of this embodiment may contain a metal (hereinafter referred to as the "target metal"). The target metal is a metal other than a T atom, and is not particularly limited, but examples include one or more selected from the group consisting of alkali metals, alkaline earth metals, and transition metals, with at least one of alkali metals and alkaline earth metals, and more preferably alkali metals. These may be contained individually or in combination.

[0025] The term "target metal" refers to a metallic element, and its elemental state is not particularly limited; at least one of ions and oxides can be exemplified, however, it is preferable that the target metal be included as at least an ion. Furthermore, a target metal that is ion-exchangeable is considered to be in at least an ionic state.

[0026] The alkali metals mentioned above are not particularly limited, but examples include one or more selected from the group consisting of sodium, potassium, rubidium, and cesium. At least one of rubidium and cesium is preferred, and cesium is more preferred, due to their high hydrocarbon desorption initiation temperatures. Two or more alkali metals may be present in the same state.

[0027] The aforementioned alkaline earth metals are not particularly limited, but examples include one or more selected from the group consisting of beryllium, magnesium, calcium, strontium, and barium, with at least one of magnesium and calcium being preferred due to their high hydrocarbon desorption initiation temperatures. Two or more of these alkaline earth metals may be present in the same state.

[0028] The transition metals mentioned above are not particularly limited, but examples include one or more selected from the group consisting of manganese, iron, cobalt, nickel, copper, molybdenum, silver, and zinc, preferably at least one of iron and copper, and more preferably copper. Two or more of these transition metals may be present together.

[0029] The target metal may be in a state where at least two or more alkali metals, alkaline earth metals, and transition metals coexist.

[0030] The content of the target metal in the hydrocarbon adsorbent of this embodiment is not particularly limited, but in terms of a high hydrocarbon desorption initiation temperature, examples include a target metal mass percentage of 1% by mass or more, 3% by mass or more, 5% by mass or more, or 10% by mass or more when the hydrocarbon adsorbent of this embodiment is considered as 100% by mass, and also 40% by mass or less, 30% by mass or less, 20% by mass or less, or 15% by mass or less. If the hydrocarbon adsorbent of this embodiment contains a binder or the like described later, the target metal mass percentage when the hydrocarbon adsorbent of this embodiment is considered as 100% by mass may be 60% by mass or less or 50% by mass or less.

[0031] Furthermore, regarding the content of the target metal in the hydrocarbon adsorbent of this embodiment, in terms of the high desorption initiation temperature of hydrocarbons, it is preferable that the ratio of target metal [mol] / Al [mol] is 0.01 or more and 10 or less, based on the amount of Al in the zeolite contained in the hydrocarbon adsorbent of this embodiment, it is more preferable that the ratio of target metal [mol] / Al [mol] is 0.02 or more and 8 or less, and it is even more preferable that the ratio of target metal [mol] / Al [mol] is 0.05 or more and 5 or less.

[0032] The metals contained in the zeolite can be those contained in the zeolite itself obtained during hydrothermal synthesis (after the crystallization process) as described later, those contained in zeolites that have been further treated with metal support, or those contained in zeolites that have been ion-exchanged with hydrogen ions or ammonium ions before being treated with metal support. The state of the target metal in this embodiment is not particularly limited, but it is preferable that the metal be in an ion-exchangeable state, that is, it is preferable that the target metal be an ion in an ion-exchangeable state. An example of an ion-exchangeable metal ion is an aluminum anion (AlO4) which is a T atom. - One example is their existence as countercations of anions such as ).

[0033] In this embodiment, an ion-exchangeable state means a state in which at least a portion of the target metal can be exchanged for another metal. This state can be confirmed by the fact that at least a portion of the target metal contained in the hydrocarbon adsorbent of this embodiment is exchanged for another metal. Examples of metal ions that are not in an ion-exchangeable state include metal ions present at ion-exchange sites such as inside closed pores, which are substantially unable to exchange ions.

[0034] The amount of the target metal in an ion-exchangeable state can be determined from the following formula. This can be quantified by ion-exchange treating the hydrocarbon adsorbent with a metal different from the target metal contained in the hydrocarbon adsorbent (hereinafter also referred to as the "exchange metal"), and measuring the difference in the content of the target metal in the hydrocarbon adsorbent before and after ion exchange.

[0035] This quantitative analysis can be performed using analytical instruments such as ICP.

[0036] [ka]

[0037] The ion exchange treatment method described above can be any general ion exchange method using an exchange metal, and may involve exchanging the target metal contained in the hydrocarbon adsorbent of this embodiment with a metal that can exchange ions (for example, if the target metal is Cs, then Na, etc.). The conditions for the ion exchange treatment are room temperature (20-35°C) and aluminum anion (AlO4), which is the T atom of the zeolite contained in the hydrocarbon adsorbent of this embodiment. - This involves circulating an excess amount (for example, 5 to 10 times the equivalent amount) of exchange metal relative to the amount of anions such as ). The exchange metal is preferably circulated in an aqueous solution containing the exchange metal. The exchange time is preferably 1 minute or more and 1 day or less.

[0038] Of the total target metal contained in the hydrocarbon adsorbent of this embodiment, the proportion of the target metal that can be ion-exchanged with an exchange metal is preferably 30 mol% to 100 mol%, and more preferably 50 mol% to 95 mol%, given the high hydrocarbon desorption initiation temperature.

[0039] In this embodiment, the hydrocarbon adsorbent containing the target metal preferably has a main peak in the MAS NMR spectrum for the target metal located at -130 ppm or below, and more preferably at -150 ppm or below, due to its high hydrocarbon desorption initiation temperature. Furthermore, the main peak may be located at -250 ppm or above, or -200 ppm or above. The main peak in the MAS NMR spectrum refers to the peak with the highest intensity among the detected peaks. The peak position refers to the chemical shift position [ppm] of the peak top for each peak.

[0040] The fact that the main peak is located below -130 ppm suggests that the interaction between the target metal and the zeolite is small, and the target metal strongly interacts with the hydrocarbons, which tends to increase the desorption initiation temperature of the hydrocarbons. Furthermore, in the zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores in this embodiment, it is thought that the hydrocarbons adsorbed in the complex-shaped pores are retained by the action of the target metal, which tends to increase the desorption initiation temperature of the hydrocarbons in particular. For example, when cesium is included as the target metal, 133 The main peak in the Cs MAS NMR spectrum is preferably located below -130 ppm, and more preferably below -150 ppm. Examples include peaks located above -250 ppm or above -200 ppm. 133 The Cs MAS NMR spectrum can be measured under the following conditions. • Pre-treatment and sampling of measurement samples: The sample to be measured is obtained by pretreatment by heating and dehydration, followed by sampling in a nitrogen glove box. Heating and dehydration is performed by raising the temperature to 400°C at 0.25°C / min under vacuum, holding for 5 hours, and then cooling to room temperature. • Measuring device Equipment name: Varian NMR System 400 (manufactured by Varian) Probe: 4mmφ solid probe Analysis software (NMR measurement): VnmrJ version 4.2 ·NMR measurement conditions Resonance frequency: 52.4MHz (133Cs) Pulse width: 3.8 μs (π / 2) Rotation frequency: 15kHz Repeat time: 2s Sampling time: 10ms Total number of times: 2048 Observation center: -150 ppm Observation range: 120kHz Reference (0 ppm): 1.0 M CsCl aqueous solution • Fourier transform conditions Points: 4096 points Window function: Exponential function (LB: 25kHz) Furthermore, in this embodiment of hydrocarbon adsorbents containing the target metal, it is preferable that the peak located on the highest magnetic field side (i.e., having the smallest chemical shift) after waveform separation in the MAS NMR spectrum for the target metal is located at -171 ppm or below, given the high desorption initiation temperature of hydrocarbons. Examples include the peak being located at -300 ppm or above, or -250 ppm or above. For example, when cesium is included as the target metal, 133 In the Cs MAS NMR spectrum, it is preferable that the peak located on the highest magnetic field side after waveform separation is located at -171 ppm or below. Furthermore, examples include the peak being located at -300 ppm or above, or -250 ppm or above. 133 Cs MAS NMR spectra can be separated by waveform under the following conditions. ·Waveform separation conditions Waveform separation software: GRAMS / AI version 8.0 (manufactured by Thermo Fisher Scientific) Separation method: Fitting with a Gaussian function The zeolite contained in the hydrocarbon adsorbent of this embodiment may have a molar ratio of silica to alumina (hereinafter also referred to as "SiO2 / Al2O3 ratio") of 2 or more and 200 or less, further 2 or more and 100 or less. Also, in terms of the high desorption start temperature of hydrocarbons, it is particularly preferable that it is 5 or more and 100 or less, 5 or more and 75 or less, 5 or more and 50 or less, 5 or more and 25 or less. Further, the SiO2 / Al2O3 ratio may be 5 or more, 10 or more or 15 or more, and may be 65 or less, 55 or less or 30 or less.

[0041] The zeolite contained in the hydrocarbon adsorbent of this embodiment has a BET specific surface area of 200 m 2 / g or more and 800 m 2 / g or less, preferably 300 m 2 / g or more and 700 m 2 / g or less is more preferable.

[0042] The zeolite contained in the hydrocarbon adsorbent of this embodiment, for example, has a crystal particle size of 0.01 μm or more or 0.1 μm or more, and may be 50 μm or less or 20 μm or less.

[0043] In addition, the hydrocarbon adsorbent of this embodiment may further contain other components such as a binder in addition to the above zeolite and target metal, and is not particularly limited. For example, one or more selected from the group consisting of silica, alumina, kaolin, attapulgite, montmorillonite, bentonite, allophane and sepiolite can be mentioned.

[0044] The desorption start temperature of the hydrocarbon adsorbent of this embodiment can be measured by the method shown below.

[0045] <Measurement sample> Shape: Hydrocarbon adsorbent with an aggregate diameter of 20-30 mesh and an irregularly formed shape. Manufacturing method: Pressure molding and crushing <Pre-treatment> Atmosphere: Nitrogen-circulating atmosphere Temperature: 500℃ Time: 1 hour <Conditions for adsorption and desorption of hydrocarbons> The sample to be measured is packed into a fixed-bed flow-through reaction tube at atmospheric pressure, and a hydrocarbon-containing gas is flowed through it under the following conditions.

[0046] Hydrocarbon-containing gas: Toluene 3000 ppmC (methane equivalent concentration) Water 3% by volume Nitrogen remainder Gas flow rate: 200 mL / min Measurement temperature: 50~600℃ Heating rate: 10°C / min <Measurement of desorption initiation temperature> The hydrocarbon concentration (methane equivalent; hereinafter also referred to as "inlet concentration") of the hydrocarbon-containing gas at the inlet side of a fixed-bed flow-through reactor tube at atmospheric pressure, and the hydrocarbon concentration (methane equivalent; hereinafter also referred to as "outlet concentration") of the hydrocarbon-containing gas at the outlet side of the fixed-bed flow-through reactor tube at atmospheric pressure are measured using a hydrogen ionization detector (FID).

[0047] The integral of the inlet concentration is used to determine the amount of hydrocarbon that has passed through the hydrocarbon adsorbent. The integral of the outlet concentration (methane equivalent concentration) is then subtracted from this amount of hydrocarbon to determine the amount of hydrocarbon adsorbed in the sample, which is defined as the amount of hydrocarbon desorption per unit mass of hydrocarbon adsorbent (μmolC / g). As the measurement temperature increases, the temperature at which the amount of hydrocarbon desorption first reaches 0 μmolC / g is defined as the desorption start temperature.

[0048] Next, the method for producing the hydrocarbon adsorbent of this embodiment will be described.

[0049] The hydrocarbon adsorbent of this embodiment consists solely of a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores, or can be manufactured by mixing the zeolite with the other components mentioned above.

[0050] The zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores contained in the hydrocarbon adsorbent of this embodiment can be produced by a manufacturing method that includes a crystallization step of hydrothermally treating a composition containing a silica source, an alumina source, an alkali source, and water (hereinafter also referred to as the "raw material composition") to obtain a crystallized product. The manufacturing method may also include a metal-containing step after the crystallization step in which a metal is added.

[0051] The silica source mentioned above is at least one of silica and its precursors, and examples include one or more selected from the group consisting of colloidal silica, amorphous silica, sodium silicate, tetraethyl orthosilicate, and aluminosilicate gel.

[0052] The alumina source mentioned above is at least one of alumina and its precursors, and includes, for example, one or more selected from the group consisting of aluminum sulfate, sodium aluminate, aluminum hydroxide, aluminum chloride, aluminosilicate gel, and metallic aluminum.

[0053] Examples of the alkali source include one or more selected from the group of various salts such as sodium, potassium, ammonium hydroxides, halides, and carbonates.

[0054] The above raw material composition may optionally contain a structure-directing agent (hereinafter also referred to as "SDA"). Examples of structure-directing agents include N,N,N-trimethyl-(+)-cis-miltanylammonium, hexamethonium, 1,1-dialkyl-4-alkylcyclohexylpiperazine-1-ium, 1,1-dialkyl-4-cyclohexylpiperazine-1-ium, 1,1'-((3as,6as)-octahydropentalene-2,5-diyl)bis(1-methylpiperidine-1-ium), and 1,1'-(butane-1,4-di 1,1'-(pentan-1,5-diyl)bis(1-methylpiperidine-1-ium), 1,1'-(hexane-1,6-diyl)bis(1-methylpiperidine-1-ium), 3-hydroxy-1-(4-(1-methylpiperidine-1-ium-1-yl)butyl)quinucidin-1-ium, 3-hydroxy-1-(5-(1-methylpiperidine-1-ium-1-yl) )Pentyl)Quinucidine-1-ium, N,N,N,N-tetraethylbicyclo[2.2.2]-octo-7-en-dipyrrolidinium, N,N-dimethyl-N'-cyclohexylpiperidineium, dimethyldipropylammonium, tetraethylammonium, 1,6-bis(N-cyclohexylpyrrolidinium)hexanedication, 1,4-bis(N-cyclohexylpiperidinium)butanedication, 1,4-bis One or more of the following can be selected from the group consisting of (N-cyclohexylpyrrolidinium)butanedication, 1,4-bis(N-cyclopentylpiperidinium)butanedication, 1,5-bis(N,N-dimethylcyclohexylammonium)pentanedication, N,N,N-trimethyltricyclo[5.2.1.0]-decaneammonium, and (6R,10S)-6,10-dimethyl-5-azoniaspiro[4.5]decanecation. Since SDA is often a cation, it is sufficient if it is included in the raw material composition as a salt paired with one or more anions selected from the group consisting of fluoride, chloride, bromide, iodide, and hydroxide (hereinafter, salts of SDA will also be referred to as "SDAX").

[0055] Preferably, the raw material composition has the following molar composition. In the following composition, SDAX is a salt of SDA, and X is an anion other than fluorine.

[0056] SiO2 / Al2O3 ratio = 2 or more and 500 or less SDAX / SiO2 ratio = 0.00 or more and 0.80 or less Na / SiO2 ratio = 0.00 or more and 0.80 or less K / SiO2 ratio = 0.00 or more and 0.80 or less X / SiO2 ratio = 0.00 or more and 2.0 or less HF / SiO2 ratio = 0.00 or more and 1.0 or less H2O / SiO2 ratio = 2 or more and 100 or less By adjusting the above conditions in various ways within the bounds of common sense of the art, it is possible to selectively produce zeolites having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores. More specific examples are not limited to these, but one example is shown below.

[0057] For example, a method for producing MSE-type zeolite involves crystallizing a raw material composition having the following molar composition. In the following composition, SDA is dimethyldipropylammonium cation, 1,1-dialkyl-4-alkylcyclohexylpiperazine-1-ium cation, 1,1-dialkyl-4-cyclohexylpiperazine-1-ium cation, 1,1'-((3as,6as)-octahydropentalene-2,5-diyl)bis(1-methylpiperidine-1-ium) cation, 1,1'-(butane-1,4-diyl)bis(1-methylpiperidine-1-ium) cation, 1,1'-(hexane-1,6-diyl)bis(1-methylpiperidine-1-ium) cation, 1,1' -(pentan-1,5-diyl)bis(1-methylpiperidine-1-ium) cation, 3-hydroxy-1-(4-(1-methylpiperidine-1-ium-1-yl)butyl)quinucidin-1-ium cation, 3-hydroxy-1-(5-(1-methylpiperidine-1-ium-1-yl)pentyl)quinucidin-1-ium cation, N,N,N,N-tetraethylbicyclo[2.2.2]-octo-7-en-dipyrrolidinium cation, N,N-dimethyl-N'-cyclohexylpiperazinium cation, and tetraethylammonium cation, one or more selected from the group, and dimethyldipropylammonium cation (hereinafter referred to as "Me2Pr2N + It is also called ". ) is preferable.

[0058] SiO2 / Al2O3 ratio = 2 or more, 15 or more, or 20 or more, 500 or less, 100 or less, or 50 or less SDA / SiO2 ratio = 0.00 or higher, 0.05 or higher, or 0.10 or higher, 0.40 or less, 0.30 or less, or 0.20 or less Na / SiO2 ratio = 0.00 or higher or 0.10 or higher, 0.80 or less, 0.40 or less, or 0.20 or less K / SiO2 ratio = 0.00 or higher or 0.10 or higher, 0.80 or less, 0.40 or less, or 0.20 or less H2O / SiO2 ratio = 2 or more or 3 or more, 100 or less, 50 or less, or 15 or less For example, a method for producing CON-type zeolite involves crystallizing a raw material composition having the following molar composition. In the following composition, SDAX is one or more selected from the group consisting of trimethyl-(-)-cismyltanylammonium hydroxide (hereinafter also referred to as "TMMAOH"), trimethyl-(-)-cismyltanylammonium iodide, and trimethyl-(-)-cismyltanylammonium hydroxydobromide, and is preferably TMMAOH.

[0059] SiO2 / Al2O3 ratio = 2 or more, 15 or more, or 20 or more, 500 or less, 100 or less, or 60 or less SDAX / SiO2 ratio = 0.00 or higher, 0.05 or higher, or 0.10 or higher, 1.00 or less, 0.80 or less, or 0.60 or less HF / SiO2 ratio = 0.00 or higher or 0.10 or higher, 1.0 or less, or 0.6 or less H2O / SiO2 ratio = 2 or more or 3 or more, 100 or less, 50 or less, or 15 or less The raw material composition may contain seed crystals, and it is preferable that the seed crystals are zeolites having a ring structure of 8 or more oxygen rings. The seed crystal content in the raw material composition (hereinafter also referred to as "seed crystal content") is preferably 0% by mass or more and 30% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, as the ratio of the mass of silicon (Si) contained in the seed crystals, converted to SiO2, to the mass of silicon (Si) contained in the raw material composition (raw material composition excluding seed crystals), converted to SiO2.

[0060] In the crystallization process, the raw material composition can be crystallized, for example, by hydrothermal treatment. While there are no particular limitations on the conditions for the hydrothermal treatment, the following conditions are examples.

[0061] Crystallization temperature: 120℃ or higher and 200℃ or lower Crystallization time: 1 hour to 20 days Crystallization pressure: Autoclaving pressure The crystallization process described above yields a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores. After the crystallization process, the obtained zeolite may be subjected to recovery, washing, drying, and calcination by any method, and may also be dealuminized to achieve an arbitrary SiO2 / Al2O3 ratio.

[0062] It is preferable to subject the material to a calcination process after the crystallization process, as this allows for an increase in the desorption initiation temperature of hydrocarbons.

[0063] The calcination process is a step in which SDA is removed from zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores. The calcination conditions are arbitrary, but examples of calcination conditions include an oxidizing atmosphere, a calcination temperature of 400°C to 800°C, and a calcination time of 0.5 hours to 12 hours.

[0064] The metal-containing step described above involves contacting the metal with a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores, with the aim of containing the metal in the zeolite. In this embodiment, it is believed that the metal-containing step makes at least a portion of the metal contained in the ion exchange sites in the zeolite skeleton having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores, capable of ion exchange, thereby raising the desorption initiation temperature of hydrocarbons.

[0065] The metals to be included are as described above.

[0066] The metal source to be included is not particularly limited, but for example, when a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores of this embodiment is to contain one or more selected from the group of sodium, potassium, rubidium, and cesium, it is preferable to use a compound containing one or more selected from the group of sodium, potassium, rubidium, and cesium, and it is even more preferable to use an inorganic salt containing one or more selected from the group of sodium, potassium, rubidium, and cesium, and further, one or more selected from the group of sulfates, nitrates, acetates, hydroxides, and chlorides containing one or more selected from the group of sodium, potassium, rubidium, and cesium.

[0067] The metal-containing process can be any method by which the metal is contained in the ion-exchange sites of a zeolite having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores. Specific methods include one or more selected from the group of ion-exchange method, evaporation to dryness method, and impregnation-supported method, with the impregnation-supported method and, more preferably, a method of mixing an aqueous solution containing a metal compound with the zeolite. This results in the metal being supported in the ion-exchange sites.

[0068] In the metal-containing process, it is preferable to intentionally create a state in which the metal does not coordinate to some of the ion exchange sites (metal coordination sites) in the zeolite skeleton having three-dimensional pores consisting of two or more pores selected from the group of 10-membered ring pores, 12-membered ring pores, 14-membered ring pores, and 18-membered ring pores, that is, to make at least a portion of the metal contained in the hydrocarbon adsorbent ion-exchangeable. The method is not particularly limited, but an example is a method in which the zeolite is used as a fixed bed and the metal is supported by circulating a metal solution through the fixed bed.

[0069] Furthermore, the manufacturing method of this embodiment may include one or more steps after the metal-containing step, such as a washing step, a drying step, and an activation step.

[0070] The cleaning process after the metal-containing process aims to remove impurities, and any cleaning method can be used. For example, the zeolite after the metal-supporting treatment may be washed with a sufficient amount of pure water.

[0071] The drying process after the metal-containing process aims to remove any remaining moisture from the surface and pores of the zeolite, and can be exemplified by processing in air at a temperature of 100°C to 200°C, preferably 110°C to 190°C.

[0072] The activation step aims to remove organic matter from the zeolite and can be exemplified by treatment in air at a temperature between 200°C and 600°C, with treatment in air at a temperature between 300°C and 600°C being preferable.

[0073] The hydrocarbon adsorbent of this embodiment can be used in any shape depending on the application, and is not particularly limited, but can be used in the form of powder, molded body, or adsorbent member, for example. Specific molded body shapes include one or more selected from the group consisting of spherical, substantially spherical, elliptical, disc-shaped, cylindrical, polyhedral, irregular shape, and petal-shaped.

[0074] When the hydrocarbon adsorbent of this embodiment is made into a molded body, the hydrocarbon adsorbent made of the zeolite described above can be molded, but it is preferable to mold a hydrocarbon adsorbent that further contains additives to the zeolite, in terms of superior operability and durability. Examples of molding methods include one or more selected from the group consisting of rolling granulation, press molding, extrusion molding, injection molding, casting, and sheet molding.

[0075] When the hydrocarbon adsorbent of this embodiment is used as an adsorbent member, the adsorbent member can be manufactured by mixing the hydrocarbon adsorbent with additives such as binders as needed in a solvent such as water or alcohol to produce a slurry, and then coating a substrate with the slurry.

[0076] The hydrocarbon adsorbent of this embodiment can be used in a hydrocarbon adsorption method.

[0077] The hydrocarbon adsorbent of this embodiment can adsorb hydrocarbons by a method that includes a step of bringing a hydrocarbon-containing fluid into contact with the hydrocarbon adsorbent of this embodiment.

[0078] Examples of hydrocarbon-containing fluids include at least one of hydrocarbon-containing gases and hydrocarbon-containing liquids.

[0079] The hydrocarbon-containing gas is a gas containing at least one hydrocarbon, and preferably contains two or more hydrocarbons. The hydrocarbons contained in the hydrocarbon-containing gas include at least one of the groups paraffins, olefins, and aromatic hydrocarbons. The number of carbon atoms in the hydrocarbon may be 1 or more, and preferably 1 to 15. Preferably, the hydrocarbons contained in the hydrocarbon-containing gas are at least one or two of the groups methane, ethane, ethylene, propylene, butane, linear paraffins with 5 or more carbon atoms, linear olefins with 5 or more carbon atoms, benzene, toluene, and xylene, more preferably at least one or two of the groups methane, ethane, ethylene, propylene, butane, benzene, toluene, and xylene, and more preferably at least one of the groups methane, ethane, ethylene, and propylene and at least one of the groups benzene, toluene, and xylene. The hydrocarbon-containing gas may also contain at least one of the groups carbon monoxide, carbon dioxide, hydrogen, oxygen, nitrogen, nitrogen oxides, sulfur oxides, and water. Specific examples of hydrocarbon-containing gases include combustion gases such as exhaust gases from internal combustion engines.

[0080] In the hydrocarbon adsorption method, the hydrocarbon-containing gas preferably contains one or more hydrocarbons selected from the group consisting of meta-xylene, ortho-xylene, and branched paraffins.

[0081] Preferably, the contact temperature in this process is room temperature to 200°C.

[0082] The hydrocarbon adsorbent of this embodiment exhibits the effect of a higher hydrocarbon desorption initiation temperature compared to hydrocarbon adsorbents other than those of this embodiment. While it is generally known that the hydrocarbon desorption initiation temperature correlates with the SAR ratio, the hydrocarbon adsorbent of this embodiment exhibits an unprecedentedly high hydrocarbon desorption initiation temperature under the same SAR conditions. In other words, the hydrocarbon adsorbent of this embodiment exhibits the effect of a high hydrocarbon desorption initiation temperature under high SAR conditions. Furthermore, a higher SAR is preferable for hydrocarbon adsorbents because it increases the hydrophobicity of the zeolite, thereby improving durability. [Examples]

[0083] The hydrocarbon adsorbents of this disclosure will be described in more detail below in the examples. However, this disclosure is not limited to these examples.

[0084] (Identification of crystal structure) XRD measurements of the sample were performed using a standard X-ray diffractometer (instrument name: UltimaIV Protectus, manufactured by Rigaku Corporation). The measurement conditions were as follows:

[0085] Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Continuous scan Scanning conditions: 40° / min Measurement range: 2θ = 3° to 43° Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Light-receiving slit: open Detector: D / teX Ultra Nifilter used The obtained XRD pattern was compared with a reference pattern to identify the crystal structure of the sample.

[0086] (composition analysis) A sample solution was prepared by dissolving the sample in a mixed aqueous solution of hydrofluoric acid and nitric acid. The sample solution was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES) using a general ICP instrument (instrument name: OPTIMA5300DV, PerkinElmer). From the obtained measurements of Si, Al, and alkali metals (Cs and Na, etc.), the SiO2 / Al2O3 molar ratio and the mass percentage of alkali metals in the sample were determined.

[0087] (Measurement of MAS NMR spectrum) As a pretreatment, a hydrocarbon adsorbent containing cesium as the target metal was heated and dehydrated, and then sampled in a nitrogen glove box to obtain the measurement sample. Heating and dehydration was performed under vacuum, raising the temperature to 400°C at 0.25°C / min, holding for 5 hours, and then cooling to room temperature. Regarding the obtained measurement sample, 133 The Cs MAS NMR spectra were measured under the following conditions. The peak with the highest intensity among the measured peaks was designated as the main peak. Furthermore, waveform separation was performed on the measured peaks. Example 1 and Comparative Example 3 133 The results of the Cs MAS NMR spectrum measurement and waveform separation are shown in Figures 1 and 2, respectively. In Figure 1, the solid line represents the raw data, the dashed line represents the fitting curve, and the dotted, dashed, double-dotted, and long dashed lines represent the separated peaks after waveform separation. In Figure 4, the solid line represents the raw data, the dashed line represents the fitting curve, and the dotted and dashed lines represent the separated peaks after waveform separation. <Condition> Equipment name: Varian NMR System 400 (manufactured by Varian) Probe: 4mmφ solid probe Analysis software (NMR measurement): VnmrJ version 4.2 ·NMR measurement conditions Resonance frequency: 52.4MHz (133Cs) Pulse width: 3.8 μs (π / 2) Rotation frequency: 15kHz Repeat time: 2s Sampling time: 10ms Total number of times: 2048 Observation center: -150 ppm Observation range: 120kHz Reference (0 ppm): 1.0 M CsCl aqueous solution • Fourier transform conditions Points: 4096 points Window function: Exponential function (LB: 25kHz) ·Waveform separation conditions Waveform separation software: GRAMS / AI version 8.0 (manufactured by Thermo Fisher Scientific) Separation method: Fitting with a Gaussian function In Example 1, Comparative Example 1, and Comparative Example 2, the spinning sideband (hereinafter also referred to as "SSB") was fitted with one waveform, and the main peak with four waveforms. In Example 2 and Comparative Example 5, the SSB was fitted with one waveform, and the main peak with three waveforms. In Comparative Example 3, the main peak was fitted with two waveforms.

[0088] (Preparation and pretreatment of hydrocarbon adsorbent samples) The desorption start temperature of hydrocarbons was measured for the hydrocarbon adsorbents obtained in the examples and comparative examples described later. The obtained hydrocarbon adsorbents were each pressure-molded and pulverized to form amorphous molded bodies with an aggregation diameter of 20 to 30 mesh, and the resulting molded bodies were used as measurement samples. 0.1 g of each measurement sample was packed into a fixed-bed flow reaction tube at atmospheric pressure, treated at 500°C for 1 hour under nitrogen flow, and then cooled to 50°C as a pretreatment.

[0089] (Hydroxide adsorption by hydrocarbon adsorbents) Hydrocarbon-containing gases were passed through each hydrocarbon adsorbent that had undergone the above pretreatment, and the amount of adsorbed hydrocarbons was measured between 50°C and 200°C to determine the amount of adsorbed hydrocarbons. The composition of the hydrocarbon-containing gases and the measurement conditions are shown below.

[0090] Hydrocarbon-containing gas: Toluene 3000 ppmC (methane equivalent concentration) Water 3% by volume Nitrogen remainder Gas flow rate: 200 mL / min Measurement temperature: 50~600℃ Heating rate: 10°C / min (Measurement of the desorption initiation temperature of hydrocarbons in hydrocarbon adsorbents) A hydrogen ionization detector (FID) was used to continuously quantitatively analyze hydrocarbons in the gas after it had passed through a hydrocarbon adsorbent. The hydrocarbon concentration (methane equivalent; hereinafter referred to as "inlet concentration") of the hydrocarbon-containing gas at the inlet side of the atmospheric pressure fixed-bed flow reaction tube and the hydrocarbon concentration (methane equivalent; hereinafter referred to as "outlet concentration") of the hydrocarbon-containing gas at the outlet side of the atmospheric pressure fixed-bed flow reaction tube were measured.

[0091] The amount of hydrocarbons that passed through the hydrocarbon adsorbent was determined by using the integral value of the inlet concentration. The amount of hydrocarbons adsorbed by each adsorbent was then calculated by subtracting the integral value of the outlet concentration (methane equivalent concentration) from this amount of hydrocarbons, and this was expressed as the amount of hydrocarbons desorbed per unit weight of hydrocarbon adsorbent (μmolC / g). The temperature at which the amount of hydrocarbon desorption first reached 0 μmolC / g as the temperature of the sample increased was defined as the desorption start temperature.

[0092] Example 1 (Synthesis of MSE-type zeolite having three-dimensional pores consisting of 12-membered ring pores and 10-membered ring pores) Nipsil LP (manufactured by Tosoh Silica Co., Ltd.), Y-type zeolite (product name: HSZ-350HUA, manufactured by Tosoh Corporation), aqueous sodium silicate solution (SiO2: 28.9 wt%, Na2O: 9.3 wt%), Me2Pr2NOH, KOH, and H2O were mixed to obtain a raw material composition having the following molar composition.

[0093] SiO2 / Al2O3 / Me2Pr2NOH / NaOH / KOH / H2O = 1 / 0.0278 / 0.17 / 0.15 / 0.15 / 5.0 (molar ratio) SiO2 / Al2O3 molar ratio = 36 Me2Pr2N+ / SiO2 molar ratio = 0.17 Na / SiO2 molar ratio = 0.15 K / SiO2 molar ratio = 0.15 H2O / SiO2 molar ratio = 5.0 5% by mass of seed crystals was added to the SiO2 of the raw material composition. The resulting raw material composition was packed into an autoclave and crystallized under rotational conditions at 160°C for 3 days under autosynthesis pressure. After crystallization, it was calcined in air at 550°C. Next, a treatment with a 10% ammonium chloride aqueous solution at 80°C for 20 hours was repeated three times, and it was dried overnight in air at 110°C. This yielded an MSE-type zeolite with an SiO2 / Al2O3 ratio of 18 and a cation type of NH4.

[0094] (Bearing Cs) A 2% by mass aqueous solution of cesium chloride (manufactured by Fujifilm Wako Pure Chemical Industries (special grade)) was prepared. The amount of cesium chloride aqueous solution used was such that the amount of Cs (moles) was 2 equivalents to the amount of Al (moles) of the zeolite obtained above. Loading was performed on the zeolite on a cake obtained by mixing MSE zeolite with water and filtering it. That is, the above cesium chloride aqueous solution was poured onto the cake. Next, water at 60°C with a volume 10 times that of the MSE type zeolite was poured in to wash it. After washing, Cs was loaded by drying at 110°C in the air, and a hydrocarbon adsorbent of this example with a Cs content of 15.8% by mass was obtained.

[0095] Example 2 (Synthesis of CON-type zeolite having three-dimensional pores consisting of 12-membered rings and 10-membered rings) A 15.9% aqueous solution of trimethyl-cis-mirtanylammonium hydroxide (TMMAOH), aluminum isopropoxide (Kishida Chemical), and tetraethoxysilane (TEOS, Kishida Chemical) were mixed and heated at 90°C for 20 hours to evaporate the water. TMMAOH was obtained by methylating (-)-cis-mirtanylamine (Aldrich) with iodomethane (Kishida Chemical), followed by ion exchange with ion exchange resin SA10AOH (Mitsubishi Chemical). The resulting solid was pulverized in a mortar, and then mixed with 48% hydrofluoric acid (Hirota Chemical Industry) and 5% by mass of CIT-1 as seed crystals to obtain the raw material composition. The molar composition of the obtained raw material composition is shown.

[0096] SiO2 / Al2O3 / TMMAOH / HF / H2O = 1 / 0.02 / 0.5 / 0.5 / 5.0 (molar ratio) SiO2 / Al2O3 ratio = 50.0 TMMAOH / SiO2 ratio = 0.5 HF / SiO2 ratio = 0.5 H2O / SiO2 ratio = 5.0 The obtained composition was sealed in an autoclave with a Teflon® inner cylinder, and the autoclave was heated at 170°C under autocatalytic pressure for 7 days while standing to obtain the product. The product was filtered, washed, and dried overnight in air at 110°C. Then, organic matter incorporated into the framework was removed by heating at 450°C for 1 hour under nitrogen, followed by heating at 600°C for 2 hours under air. This yielded a CON-type zeolite with an SiO2 / Al2O3 ratio of 53 and a cation type of H. The hydrocarbon adsorbent of this example, with a Cs content of 4.6% by mass, was obtained by the same method as in Example 1, except that the obtained CON-type zeolite was used.

[0097] Comparative Example 1 (*Synthesis of BEA-type zeolite) A 35 wt% TEAOH aqueous solution, a 48 wt% potassium hydroxide aqueous solution, pure water, and amorphous aluminosilicate (SiO2 / Al2O3 = 18.2) were mixed, and then 1.5 wt% zeolite β (product name: HSZ930NHA, manufactured by Tosoh Corporation) was added as a seed crystal to obtain a raw material composition having the following molar composition.

[0098] SiO2 / Al2O3 ratio =18.2 TEAOH / SiO2 ratio =0.12 K / SiO2 ratio =0.12 H2O / SiO2 ratio =12.0 Seed crystal =1.5% by mass The raw material composition was filled into a sealed container, and the container was rotated at 55 rpm while the raw material composition was reacted at 150°C for 48 hours to obtain crystals. The obtained crystals were separated into solid and liquid phases, washed with pure water, and then dried in the air at 110°C to recover. The obtained crystals were calcined in the air at 600°C for 2 hours and treated with a 20% ammonium chloride aqueous solution, and then dried overnight in the air at 110°C. This yielded a BEA-type zeolite (zeolite β) having a three-dimensional pore structure consisting only of 12-membered ring pores with an SiO2 / Al2O3 ratio of 18 and a cation type of NH4.

[0099] The hydrocarbon adsorbent for this comparative example was obtained in the same manner as in Example 1, except that the *BEA-type zeolite obtained above was used instead of the MSE-type zeolite.

[0100] Comparative Example 2 (Synthesis of YFI-type zeolite) Colloidal silica AS-40 (manufactured by GRACE), zeolite Y (product name: HSZ-350HUA, manufactured by Tosoh Corporation), Me2Pr2NOH, NaOH, KOH, and H2O were mixed to obtain a raw material composition having the following molar composition.

[0101] SiO2:0.025 Al2O3:0.17 Me2Pr2NOH:0.15 NaOH:0.17 KOH:7 H2O SiO2 / Al2O3 ratio =40 Me2Pr2NOH / SiO2 ratio =0.17 Na+K / SiO2 ratio =0.32 H2O / SiO2 ratio =7.0 The obtained raw material composition was packed into an autoclave and crystallized at 160°C for 6 days under standing conditions. After crystallization, it was calcined at 550°C in air and treated with a 20% ammonium chloride aqueous solution, and dried overnight at 110°C in air. This yielded a YFI-type zeolite having a three-dimensional pore structure consisting only of 12-membered ring pores with an SiO2 / Al2O3 ratio of 18 and a cation type of NH4.

[0102] The hydrocarbon adsorbent for this comparative example was obtained in the same manner as in Example 1, except that the YFI-type zeolite obtained above was used instead of the MSE zeolite.

[0103] Comparative Example 3 The hydrocarbon adsorbent for this comparative example was obtained in the same manner as in Example 1, except that a MOR-type zeolite with a one-dimensional pore structure (product name: HSZ-640HOA, manufactured by Tosoh Corporation, SiO2 / Al2O3=19) was used instead of an MSE-type zeolite.

[0104] Comparative Example 4 The hydrocarbon adsorbent for this comparative example was obtained in the same manner as in Example 1, except that instead of MSE zeolite, MFI-type zeolite (product name: HSZ-870NHA, manufactured by Tosoh Corporation; SiO2 / Al2O3=70) was calcined at 570°C for 2 hours in an air atmosphere to obtain an MFI-type zeolite having a three-dimensional pore structure consisting only of 10-membered ring pores with a cation type of H.

[0105] Comparative Example 5 The hydrocarbon adsorbent of this comparative example was obtained in the same manner as in Example 1, except that an MFI type zeolite (product name: HSZ-850NHA, manufactured by Tosoh Corporation; SiO2 / Al2O3=51) was calcined at 570°C for 2 hours in an air atmosphere to obtain an MFI type zeolite with a three-dimensional pore structure consisting only of 10-membered ring pores, resulting in an H-type cation, instead of an MSE type zeolite.

[0106] Comparative Example 6 The hydrocarbon adsorbent for this comparative example was obtained in the same manner as in Example 1, except that an MFI type zeolite (product name: HSZ-840NHA, manufactured by Tosoh Corporation; SiO2 / Al2O3=39) having a three-dimensional pore structure consisting only of 10-membered ring pores was used instead of an MSE type zeolite.

[0107] The results for Example 1 and Comparative Examples 1 to 3 are shown in the table below.

[0108] [Table 1]

[0109] From the table above, it can be seen that, for zeolites with similar SiO2 / Al2O3 ratios and target metal content, zeolites with three-dimensional pores exhibit a higher desorption initiation temperature than zeolites with one-dimensional pores. Furthermore, a comparison of Example 1 and Comparative Example 1 confirms that zeolites with three-dimensional pores consisting of 10-membered rings and 12-membered rings are hydrocarbon adsorbents that exhibit a higher desorption initiation temperature than zeolites with three-dimensional pores consisting only of 12-membered rings.

[0110] Next, the results for Example 2 and Comparative Examples 4 to 6 are shown in the table below.

[0111] [Table 2]

[0112] In the table above, "-" indicates that the value has not been measured. Examples 2 and Comparative Examples 4 to 6 are all zeolites having three-dimensional pores. From Comparative Examples 4 to 6, it can be confirmed that the desorption initiation temperature tends to decrease with decreasing SiO2 / Al2O3 ratio, and that as the SiO2 / Al2O3 ratio decreases from 70 to 39, the desorption initiation temperature increases by about 20°C, from 143°C to 165°C. On the other hand, although Example 2 has an SiO2 / Al2O3 ratio of 53, which is about the same as Comparative Example 5, it can be confirmed that the desorption initiation temperature is about the same as that of Comparative Example 6, which has an SiO2 / Al2O3 ratio that is 10 or more lower than that of Comparative Example 5. From this, it can be confirmed that the hydrocarbon adsorbent of this embodiment exhibits a high desorption initiation temperature at a high SiO2 / Al2O3 ratio, which was previously only achievable with conventional hydrocarbon adsorbents in the low SiO2 / Al2O3 ratio range.

Claims

1. A hydrocarbon adsorbent comprising a zeolite having a CON structure (excluding zeolites having a CON structure containing boron), and containing at least one of the metals rubidium and cesium in an amount of 1% by mass or more and 20% by mass or less.

2. The hydrocarbon adsorbent according to claim 1, wherein the amount of the metal is 3% by mass or more and 15% by mass or less.

3. The hydrocarbon adsorbent according to claim 1 or 2, wherein the ratio of at least one of rubidium and cesium metal [mol] / Al [mol] is 0.01 or more and 10 or less.

4. The hydrocarbon adsorbent according to any one of claims 1 to 3, wherein the metal is cesium.

5. １３３ The hydrocarbon adsorbent according to claim 4, wherein the main peak in the Cs MAS NMR spectrum is located between -300 ppm and -130 ppm.

6. １３３ The hydrocarbon adsorbent according to claim 5, wherein the main peak in the Cs MAS NMR spectrum is located between -250 ppm and -150 ppm.

7. The zeolite has a molar ratio of silica to alumina (SiO ２ / Al ２ O ３ A hydrocarbon adsorbent according to any one of claims 1 to 6, wherein the zeolite has a ratio of 2 or more and 200 or less.

8. The zeolite has a molar ratio of silica to alumina (SiO ２ / Al ２ O ３ A hydrocarbon adsorbent according to any one of claims 1 to 7, wherein the zeolite has a ratio of 2 to 100.

9. A method for adsorbing hydrocarbons, characterized by contacting a hydrocarbon-containing fluid with a hydrocarbon adsorbent according to any one of claims 1 to 8.

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