JP7632039B2 - Silver-alkaline earth metal-containing MFI type zeolite and catalyst for producing hydrocarbons - Google Patents

Description

The present invention relates to a metal-containing MFI-type zeolite containing silver and alkaline earth metals and a catalyst for producing hydrocarbons comprising the same. More specifically, the present invention relates to a catalyst for producing hydrocarbons, which is a catalyst for simultaneously producing light hydrocarbon compounds and aromatic compounds, and which has a specific average particle size and specific amounts of silver and alkaline earth metals, and exhibits excellent performance in terms of productivity, stability, and long life when producing aromatic compounds from aliphatic hydrocarbons, while enabling the simultaneous production of light C2-C3 hydrocarbon compounds in a balanced manner with high yields.

MFI zeolite is used as a highly selective catalyst that utilizes the uniform pores derived from the zeolite structure. Examples of using MFI zeolite as a catalyst include the disproportionation of toluene (see, for example, Patent Document 1) and the isomerization of xylene (see, for example, Patent Document 2).

These reactions mainly take advantage of the characteristics of the micropores in MFI zeolite. The micropores in MFI zeolite have an entrance diameter of approximately 0.5 nm, and are thought to be an effective reaction site for molecules with molecular diameters close to this pore diameter.

Furthermore, research is being conducted on MFI-type zeolites that have pores larger than micropores (less than 2 nm), i.e., mesopores (pore diameter 2 to 50 nm) (see, for example, Non-Patent Document 1).

As a promising material for industrial use, a new MFI-type zeolite with uniform mesopores of 10 nm or more and its manufacturing method (see, for example, Patent Document 3) have been proposed. However, there have been only a few reports of specific results being obtained by using zeolites with mesopores as catalysts, especially in reactions using relatively small molecules with 10 or fewer carbon atoms as raw materials.

Benzene, toluene, and xylene (hereinafter, collectively referred to as aromatic compounds) are often obtained by decomposing feedstock oil (e.g., naphtha, etc.) obtained by petroleum refining in a thermal cracking reactor, and separating and refining aromatic compounds from the obtained thermal cracking products by distillation or extraction. In the production of aromatic compounds by these production methods, aliphatic hydrocarbons (including paraffinic, olefinic, acetylene, and alicyclic) are included as thermal cracking products other than aromatic compounds. Therefore, since aliphatic hydrocarbons are simultaneously produced along with the production of aromatic compounds, the production amount of aromatic compounds is adjusted according to the production amount of aliphatic hydrocarbons, and the production amount is naturally limited. In addition, aromatic compounds can be produced by contacting aliphatic hydrocarbon feedstock with a catalyst mainly containing medium pore size zeolite at a temperature of about 400°C to about 800°C (see, for example, Non-Patent Documents 2 to 5). Compared with the production method of aromatic compounds by thermal cracking, this production method has the advantage of being low in added value and being able to produce aromatic compounds from surplus hydrocarbon feedstock. Catalysts for use in the production of these aromatic compounds have also been developed. For example, as a catalyst for producing aromatic compounds using hydrocarbons containing paraffins, olefins, and naphthenes as raw materials, a zinc-supported intermediate pore size zeolite catalyst with reduced zinc scattering has been provided (see, for example, Patent Document 4). In addition, as a catalyst for producing aromatic compounds using paraffins, olefins, acetylene-based hydrocarbons, cyclic paraffins, and cyclic olefins as raw materials, a catalyst in which platinum and a halogen component are simultaneously supported on L-type zeolite has been provided (see, for example, Patent Document 5). Furthermore, an aromatization reaction catalyst has been provided, which is characterized in that zinc and/or gallium are supported on a structure having a size of 0.1 to 100 mm, a crystalline porous aluminosilicate present on the surface layer of the structure, and an inorganic support present in the inner layer except for the surface layer of the structure (see, for example, Patent Document 6). In addition, catalysts for producing aromatic compounds using hydrocarbons as raw materials have been provided (see, for example, Patent Documents 7 and 8). In recent years, proposals have also been made regarding aromatic compound production catalysts containing specific MFI-type zeolites (see, for example, Patent Document 9), silver-containing zeolites with high heat resistance and hydrothermal resistance (see, for example, Patent Document 10), etc.

Patent No. 4014279 Patent No. 2598127 JP 2013-227203 A Japanese Patent Application Publication No. 10-33987 Patent No. 3264447 Patent No. 5447468 Patent No. 3966429 Patent No. 5564769 JP 2017-127857 A JP 2018-154538 A

Microporous and Mesoporous Materials, Vol. 137, p. 92 (2011) Industrial & Engineering Chemistry Research, Vol. 31, p. 995 (1992) Industrial & Engineering Chemistry Research, Vol. 26, p. 647 (1987) Applied Catalysis Vol. 78, p. 15 (1991) Microporous and Mesoporous Materials, Vol. 47, p. 253 (2001)

However, in the methods for producing aromatic compounds using catalytic reactions provided in Patent Documents 4 to 8, there was an issue with the catalyst life (the time from when the catalyst is active after the start of the reaction until it becomes inactive) from the perspective of production costs. In addition, the proposals in Patent Documents 9 and 10 were effective in terms of producing aromatic compounds, but no consideration was given to the production of light hydrocarbon compounds.

The present invention provides a novel catalyst that enables the simultaneous, selective, and balanced production of light hydrocarbon compounds (hydrocarbon compounds having 2 to 3 carbon atoms) and aromatic compounds from aliphatic hydrocarbons, which are relatively small molecules (particularly those having 10 or less carbon atoms, preferably 4 to 6 carbon atoms), in high yields, over a long period of time, and a metal-containing MFI-type zeolite that can be used therewith.

As a result of intensive research conducted by the inventors to solve the above problems, they discovered that a specific MFI-type zeolite into which silver and an alkaline earth metal have been introduced can serve as a catalyst that enables the simultaneous production of light hydrocarbon compounds and aromatic compounds from aliphatic hydrocarbons selectively, stably over a long period of time, and in a balanced and high yield, and thus completed the present invention.

That is, the present invention relates to a silver-alkaline earth metal-containing MFI zeolite which is characterized by satisfying the following characteristics (i) to (v), and a catalyst for simultaneously producing light hydrocarbon compounds and aromatic compounds comprising the same:
(i) The average particle diameter (PD) is PD≦100 nm.
(ii) The mesopore distribution curve has a peak, the half width (hw) of the peak is hw≦20 nm, the center value (μ) of the peak is 10 nm≦μ≦20 nm, and the mesopore volume (pv) of the mesopores corresponding to the peak is 0.05 ml/g≦pv.
(iii) In powder X-ray diffraction measurement at a diffraction angle of 2θ, there is no peak in the range of 0.1 to 3 degrees.
(iv) the silver content is 0.05 to 3 wt %;
(v) The alkaline earth metal content is 0.05 to 5 wt. %.

The present invention is described in detail below.

The novel silver-alkaline earth metal-containing MFI zeolite of the present invention satisfies the above characteristics (i) to (v), and MFI zeolite refers to an aluminosilicate compound that belongs to the structure code MFI defined by the International Zeolite Society.

The novel silver-alkaline earth metal-containing MFI zeolite of the present invention has (i) a PD≦100 nm, and since it is a zeolite with particularly excellent thermal stability, it is desirable that the PD is 5 nm≦PD≦100 nm. Here, if the PD exceeds 100 nm, the reaction efficiency will be poor when used as a catalyst for hydrocarbon conversion reactions.

The method for measuring PD in the present invention is not limited, and any method can be used, such as a method in which 100 or more particles are arbitrarily selected from a photograph taken with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) and the average diameter is calculated, or a method in which the average diameter is calculated from the external surface area of zeolite using the following formula (1).
PD=6/S×(1/(2.29×10 ⁶ )+0.18×10 ⁻⁶ ) (1)
(Here, S indicates the external surface area (m ² /g).)
The external surface area (S (m ² /g)) in formula (1) can be determined by a t-plot method using a general nitrogen adsorption method at liquid nitrogen temperature. For example, when t is the thickness of the adsorption amount, measurement points in the range of 0.6 to 1 nm for t are linearly approximated, and the external surface area of the zeolite is determined from the slope of the obtained regression line.

Among these, SEM or TEM methods are preferred because they allow for simple measurements.

The novel silver-alkaline earth metal-containing MFI zeolite of the present invention (ii) has a mesopore distribution curve with a peak, the half-width (hw) of the peak is hw≦20 nm, the center value (μ) of the peak is 10 nm≦μ≦20 nm, and the mesopore volume (pv) of the mesopores corresponding to the peak is 0.05 ml/g≦pv. The mesopores referred to in the present invention are mesopores defined by IUPAC and indicate pores with a pore diameter in the range of 2 to 50 nm. The mesopores can be measured by a general nitrogen adsorption method at liquid nitrogen temperature. The pore volume of the mesopores can be obtained by analyzing the measurement results obtained by the nitrogen adsorption method. For example, the following method can be used for the analysis.

Specific examples include a method for analyzing the desorption process using the Barret-Joyner-Halenda method (Journal of the American Chemical Society, 1951, pp. 373-380). For example, the total pore volume of mesopores can be obtained by integrating the amount of nitrogen gas desorbed in the range of pore diameters from 2 nm to 50 nm.

In addition, by first obtaining a cumulative curve with the nitrogen desorption amount per unit mass V/m (mL/g) on the vertical axis and the mesopore diameter D (nm) on the horizontal axis, and then taking the differential value (d(V/m)/d(D)) of the amount of nitrogen gas desorbed from the mesopores with respect to the mesopore diameter value on the vertical axis, it is possible to obtain the peak of the increase in the amount of nitrogen desorption per unit mass at the mesopore diameter.

The novel silver-alkaline earth metal-containing MFI zeolite of the present invention comprises an MFI zeolite having a group of mesopores with a nearly uniform pore diameter, and in the present invention, a group of mesopores with a nearly uniform pore diameter may be referred to as a uniform mesopore. Specifically, the uniform mesopore refers to a mesopore having a pore diameter within a range (μ±2σ) of twice the standard deviation (2σ) from the center value (μ) of the Gaussian function, which is obtained by approximating the maximum peak among the peaks related to mesopores in the pore distribution curve with a Gaussian function. The pore volume of the uniform mesopores can be calculated by integrating the amount of nitrogen gas desorbed within the range of μ±2σ.

The silver-alkaline earth metal-containing MFI zeolite of the present invention is, among MFI zeolites having a nearly uniform group of mesopores, (ii) an MFI zeolite having a more uniform group of mesopores, in which the mesopore distribution curve has a peak, the half-width (hw) of the peak is hw≦20 nm, the center value (μ) of the peak is 10 nm≦μ≦20 nm, and the mesopore volume (pv) of the mesopores corresponding to the peak is pv≧0.05 ml/g.

The silver-alkaline earth metal-containing MFI zeolite of the present invention has a peak in the mesopore distribution curve, and the peak is an MFI zeolite having a group of almost uniform mesopores with small variation in the pore diameter size, which is hw≦20 nm or less, and therefore has excellent reaction selectivity. This effect is more pronounced and preferable when hw≦15 nm, especially hw≦10 nm. The lower limit of hw is not particularly limited, but it is preferable that it is 1 nm or more because it will have better reaction selectivity. Note that if hw>20 nm, the reaction selectivity will be poor when used as a catalyst for producing hydrocarbon compounds. In addition, by including an MFI zeolite with a center value (μ) of 10 nm≦μ≦20 nm when the peak is approximated by a Gaussian function, it becomes possible to selectively react even with molecules of larger sizes, and it becomes an excellent catalyst for producing hydrocarbon compounds. Furthermore, by satisfying pv≧0.05 ml/g, the catalyst used will have a long life for producing hydrocarbon compounds, and it is preferable that 0.05 ml/g≦pv≦0.70 ml/g, particularly preferably 0.10 ml/g≦pv≦0.70 ml/g, and even more preferably 0.20 ml/g≦pv≦0.50 ml/g. Here, if pv<0.05 ml/g, the pores will be easily clogged due to the accumulation of coke and other by-products produced during the reaction, resulting in a poor catalyst life when used as a catalyst.

In addition, since the silver-alkaline earth metal-containing MFI zeolite of the present invention is particularly suitable as a catalyst for producing hydrocarbon compounds that enables selective reactions, the ratio of pv to the total pore volume (pvr) shown in (ii) above is preferably 30%≦pvr≦100%, and more preferably 40%≦pvr≦100%.

The silver-alkaline earth metal-containing MFI zeolite of the present invention (iii) has no peaks in the range of 0.1 to 3 degrees in powder X-ray diffraction measurement with a diffraction angle of 2θ. This indicates that there is no regularity in the arrangement of mesopores and that there are no walls separating the mesopores. When used as a catalyst, this facilitates material transfer between the mesopores, making it a catalyst for producing hydrocarbon compounds with excellent reaction efficiency.

The silver-alkaline earth metal-containing zeolite of the present invention (iv) has a silver content of 0.05 to 3 wt %, and by having a silver content within a specific range, it exhibits particularly excellent catalytic performance when used as a catalyst for producing hydrocarbon compounds. Here, if the silver content is less than 0.05 wt %, the acid site protection effect of silver cannot be obtained, and the catalytic performance of production efficiency and selectivity when used as a catalyst for producing hydrocarbon compounds is inferior. On the other hand, if it exceeds 3 wt %, the aggregation of silver progresses, side reactions and caulking are likely to occur on the surface of the silver aggregate particles, and the catalytic performance is deteriorated.

The silver-alkaline earth metal-containing zeolite of the present invention has an alkaline earth metal content of 0.05 to 5 wt %, and by containing an alkaline earth metal within a specific range, it is useful as a catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds, which enables the simultaneous, selective and stable production of light hydrocarbon compounds and aromatic compounds from aliphatic hydrocarbons over a long period of time. Examples of alkaline earth metals include calcium, strontium, barium, and radium, and one or more selected from the group consisting of calcium, strontium, and barium are preferable because they exhibit excellent properties as a catalyst for the production of hydrocarbon compounds. Here, if the alkaline earth metal content is less than 0.05 wt %, the selectivity for light hydrocarbon compounds will be poor. Also, if it exceeds 5 wt %, the stability as a catalyst for the simultaneous production will be poor.

The silver-alkaline earth metal-containing MFI zeolite of the present invention is not limited in terms of its SiO ₂ /Al ₂ O ₃ (molar ratio), and it is preferable that the SiO ₂ /Al ₂ O ₃ (molar ratio) be 20 or more and 200 or less, since this zeolite serves as a catalyst for producing hydrocarbon compounds that is excellent in heat resistance, reaction selectivity, and productivity.

The silver-alkaline earth metal-containing MFI type zeolite of the present invention is preferably one that does not contain a structure directing agent such as tetrapropylammonium salt within the pores, since it serves as a catalyst for producing hydrocarbon compounds with excellent reaction selectivity and productivity.

The following method can be mentioned as an example of a method for producing MFI zeolite, a raw material that satisfies the above characteristics (i) to (iii).

Amorphous aluminosilicate gel is added to an aqueous solution of tetrapropylammonium (hereinafter sometimes referred to as "TPA") hydroxide and sodium hydroxide to form a suspension, MFI type zeolite is added to the resulting suspension as seed crystals to form a raw material composition, and the resulting raw material composition is crystallized and fired to obtain MFI type zeolite.

The silver-alkaline earth metal-containing MFI type zeolite of the present invention further preferably has (vi) an outer surface acid amount of 0.01 mmol/g or less, and particularly preferably 0.0001 to 0.01 mmol/g. Here, the outer surface acid site of a zeolite, as the term implies, indicates an acid site present on the outer surface of the zeolite. Normally, a zeolite has acid sites on its outer surface and in its (micro)pores, and not having acid sites on the outer surface means that the acid sites are present only in the (micro)pores. And, since it has excellent heat resistance, hot water resistance, and durability, it is preferable that the silver-alkaline earth metal-containing MFI type zeolite has an unmodified surface that is not coated with silicate, dialkylamine reagent, or the like.

The acid sites on the external surface of zeolites can be confirmed by any method that allows such confirmation. For example, they can be confirmed by adsorption of 2,4-dimethylquinoline, which has an adsorption property for acid sites (see Characterization of acid sites on the external surface of zeolites, Reaction Kinetics and Catalysis Letters, vol. 67, p. 281 (1999)).

The silver-alkaline earth metal-containing MFI zeolite of the present invention preferably has an acid amount (vii) of 0.05 to 0.85 mmol/g, and more preferably 0.05 to 0.55 mmol/g. The acid amount can be measured using a method generally known as a method for measuring acid amount, for example, a method based on the ammonia-TPD method (see Measurement of solid acidity by ammonia temperature-programmed desorption method, Catalysts, vol. 42, p. 218 (2000)).

As a method for producing MFI zeolite satisfying any one of (vi) to (vii), it is possible to produce it by, for example, dealumination of the aluminum in the framework of MFI zeolite, which is a raw material satisfying the above characteristics (i) to (iii), using steam or the like. The temperature of the steam treatment is, for example, preferably 400 to 900°C, particularly preferably 450 to 800°C, and more preferably 500 to 700°C. The partial pressure of the steam is preferably 0.001 to 5 MPa, particularly preferably 0.01 to 0.5 MPa, and more preferably 0.05 to 0.2 MPa. The concentration of the steam is preferably, for example, 0.01 to 100 vol% water steam/dilution gas. The dilution gas may be an inert gas such as nitrogen, air, oxygen, carbon monoxide, carbon dioxide, or a mixture thereof. The steam treatment time can be selected arbitrarily.

The silver-alkaline earth metal-containing MFI zeolite of the present invention is a catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds that is particularly well-balanced when producing these compounds, so it is preferable that the silver to alkaline earth metal content is (viii) silver/alkaline earth metal (weight ratio) in the range of 100/100 to 500/100.

The silver-alkaline earth metal-containing MFI zeolite of the present invention can be produced by, for example, adding silver and alkaline earth metal to MFI zeolite by methods such as impregnation, ion exchange, and physical mixing.

The silver-alkaline earth metal-containing MFI zeolite of the present invention may be used as a catalyst for producing hydrocarbon compounds in any form, and may be used in any form, such as by using the silver-alkaline earth metal-containing MFI zeolite powder as it is as a catalyst, by compressing and molding it into a specific shape, or by mixing it with a binder or the like and molding it into a specific shape.

By using the silver-alkaline earth metal-containing MFI type zeolite of the present invention as a catalyst for producing hydrocarbon compounds, it becomes a catalyst with excellent efficiency in terms of reaction selectivity, productivity, etc., and by contacting it with, for example, aliphatic hydrocarbons, particularly aliphatic hydrocarbons having 10 or less carbon atoms, and further aliphatic hydrocarbons having 4 to 6 carbon atoms, it becomes possible to efficiently and balancedly produce light hydrocarbon compounds and aromatic compounds simultaneously. In this case, the aliphatic hydrocarbons include, for example, paraffinic, olefinic, acetylene, and alicyclic hydrocarbons, and specific examples thereof include paraffinic, such as butane, isobutane, pentane, and hexane; olefinic, such as butene, isobutene, pentene, and hexene; alicyclic, such as cyclohexane, and mixtures thereof.

In the reaction of the embodiment, the reaction temperature is not particularly limited, and may be any temperature that allows the production of hydrocarbon compounds such as light hydrocarbon compounds and aromatic compounds. In particular, the reaction temperature is preferably in the range of 400 to 800°C, since it suppresses the production of by-product paraffins, olefins, or alkanes and provides an efficient reaction between light hydrocarbon compounds and aromatic compounds without requiring a heat-resistant reaction apparatus more than necessary. There is also no restriction on the reaction pressure, and operation is possible within a pressure range of, for example, about 0.05 MPa to 5 MPa. The supply of aliphatic hydrocarbons, which are reaction raw materials, to the catalyst for simultaneous production of light hydrocarbon compounds and aromatic compounds at that time is not particularly limited as the ratio of the volume of the raw material gas to the volume of the catalyst, and can be, for example, a space velocity of about 1h ^-1 to 50,000h ^-1 . When the aliphatic hydrocarbons are supplied as raw material gas, they can be used as single gases, mixed gases, and those diluted with a single or mixed gas selected from an inert gas such as nitrogen, hydrogen, carbon monoxide, and carbon dioxide.

There are no limitations on the reaction type, and for example, fixed bed, transport bed, fluidized bed, moving bed, multi-tubular reactor, as well as continuous flow, intermittent flow and swing reactors, etc. can be used.

The light hydrocarbon compounds produced include C2-C3 hydrocarbon compounds such as ethane, ethylene, propane, and propylene, with ethylene being particularly preferred. The aromatic compounds are not particularly limited as long as they fall into the category of aromatic compounds, and examples include benzene, toluene, xylene, trimethylbenzene, ethylbenzene, propylbenzene, butylbenzene, naphthalene, and methylnaphthalene, with benzene, toluene, and xylene being particularly preferred. Since this method provides a hydrocarbon compound production method with an excellent balance between the production of light hydrocarbon compounds and aromatic compounds, it is preferable to produce C2-C3 hydrocarbon compounds/aromatic compounds (weight ratio) of 80/100 to 180/100.

The present invention relates to a specific MFI-type zeolite containing a new silver-alkaline earth metal, which can be used as a catalyst for producing hydrocarbon compounds that can provide a specifically high yield, good balance, and a long catalyst life, particularly when simultaneously producing light hydrocarbon compounds and aromatic compounds from aliphatic hydrocarbons, and is therefore extremely useful industrially.

The present invention will be explained in detail below with reference to examples.

The performance of the MFI zeolite used in the examples as a catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds was measured and defined by the following method.

- Measurement of pore distribution, pore diameter, and external surface area -
The pore distribution and pore diameter of the MFI zeolite were measured by nitrogen adsorption measurement.

The nitrogen adsorption measurements were performed using a nitrogen adsorption device (OMNISORP360CX, manufactured by Beckman Coulter) at 30 torr/step for both adsorption and desorption. The external surface area was calculated by linear approximation of the thickness of the adsorption layer (t = 0.6 to 1.0 nm) using the t-plot method.

The desorption process of the nitrogen adsorption measurement was analyzed using the Barret-Joyner-Halenda method (Journal of the American Chemical Society, 1951, pp. 373-380), and a mesopore distribution curve was obtained in which the horizontal axis represents the pore diameter constant and the vertical axis represents the differential value of the amount of desorbed nitrogen gas. The total pore volume of the mesopores was calculated by integrating the amount of desorbed nitrogen gas in the range of 2 nm to 50 nm.

The maximum peak of the differential value (d(V/m)/d(D)) of the amount of nitrogen gas desorbed from the mesopores with respect to the mesopore diameter value was analyzed using the intensity approximation of a Gaussian function, and mesopores with diameters within a range of twice the standard deviation (2σ) (=μ±2σ) from the center value (μ) of the Gaussian function were defined as uniform mesopores. The pore volume of uniform mesopores was calculated by integrating the amount of nitrogen gas desorbed within a range of ±2σ based on the center value (μ).

～Measurement of average particle size～
The average particle diameter was calculated from the external surface area using the above formula (1). In formula (1), S is the external surface area (m ² /g) and PD is the average particle diameter (m). The external surface area (S (m ² /g)) in formula (1) was determined by the t-plot method using a nitrogen adsorption method at liquid nitrogen temperature.

- Measurement of silver and alkaline earth metal introduction amount -
The amount of silver and alkaline earth metal introduced into the zeolite was determined by dissolving the MFI zeolite in a mixed aqueous solution of hydrofluoric acid and nitric acid, and measuring the resultant solution by inductively coupled plasma atomic emission spectrometry (ICP-AES) using a general ICP apparatus (product name: OPTIMA3300DV, manufactured by PerkinElmer).

~ Powder X-ray diffraction measurement ~
Measurements were performed in air using an X-ray diffraction measurement device (Spectris Corporation, product name: X'pert PRO MPD) with a tube voltage of 45 kV, a tube current of 40 mA, and CuKα1. The range of 0.04 to 5 degrees was analyzed at 0.08 degree/step and 200 seconds/step. In addition, the background corrected for the absorption rate of the direct beam was removed. The presence or absence of peaks was confirmed by visual inspection.

- Measuring the amount of outer surface acid -
The amount of external surface acid was measured by 2,4-dimethylquinoline adsorption infrared absorption spectroscopy. The measurement was performed by a transmission method using an FT-IR measurement device ((trade name) FT/IR-6700, manufactured by JASCO Corporation). The spectrum was obtained by 256 integration times using an MCT detector. The sample was molded into a disk with a diameter of 13 mm, and then placed in a disk holder in a quartz vacuum degassing cell, so that it was placed vertically on 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 2,4-dimethylquinoline adsorption was measured. 2,4-dimethylquinoline gas was introduced and adsorbed for 30 minutes, and after evacuation at 150°C for 1 hour, the infrared absorption spectrum after 2,4-dimethylquinoline adsorption was measured. The difference between the infrared absorption spectrum after 2,4-dimethylquinoline adsorption and the spectrum before adsorption was taken to measure the change in infrared absorption due to adsorption. In this difference spectrum, the peak near 3600 cm ^-1 is the absorption spectrum peak of 2,4-dimethylquinoline adsorbed on the outer surface acid site (Bronsted acid site). After calculating the integrated intensity, the amount of outer surface acid was calculated from the following formula (2) according to the Lambert-Beerr law.
Acid amount (μmol/mg) = A・S/(W・ε) (2)
(Here, A is the peak area intensity (cm ⁻¹ ) of the peak of interest, S is the sample cross-sectional area (cm ² ), W is the sample weight (mg), and ε is the integrated extinction coefficient, 3.7 cm·μmol ⁻¹ .)
～Acid amount measurement～
The amount of acid was measured by pyridine adsorption infrared absorption spectroscopy. The same apparatus and method were used as in the above 2,4-dimethylquinoline adsorption infrared absorption spectroscopy, except that pyridine gas was introduced and adsorbed for 10 minutes.

The peak near 1545 cm ⁻¹ in the difference spectrum was used as the peak of the absorption spectrum of pyridine adsorbed to the Bronsted acid site, and the amount of acid was calculated from the above formula (2) using an integrated absorption coefficient of 1.67 cm·μmol ⁻¹ .

- Hydrocarbon compound production equipment and its manufacturing method -
The MFI zeolite obtained in the examples and the catalyst for simultaneous production of light hydrocarbon compounds and aromatic compounds containing the same were used to produce light hydrocarbon compounds and aromatic compounds by the following methods, and the products were evaluated.

A fixed-bed gas-phase flow reactor using stainless steel reaction tubes (inner diameter 16 mm, length 900 mm) was used. A catalyst for producing hydrocarbon compounds was packed in the middle of each stainless steel reaction tube, and after heating pretreatment under dry air flow, the raw material gas was fed. The reactor equipment conditions and operating conditions are not limited to those described in this example, and can be selected as appropriate. A ceramic tubular furnace was used for heating, and the temperature of the catalyst layer was controlled. The reaction outlet gas and reaction liquid were collected, and the gas and liquid components were analyzed individually using a gas chromatograph. The gas components were analyzed using a gas chromatograph (Shimadzu Corporation, (product name) GC-1700) equipped with a TCD detector. The packing material used was Waters' PorapakQ (product name) or GL Science's MS-5A (product name). The liquid components were analyzed using a gas chromatograph (Shimadzu Corporation, (product name) GC-2015) equipped with an FID detector. The separation column used was a capillary column (GL Sciences, product name: TC-1).

The reaction conditions were set as follows:

(Manufacturing conditions)
Catalyst temperature: 585°C.
Flowing gas: a mixed gas of 1-butene 125 ml/min, 2-butene 75 ml/min, isobutene 225 ml/min, normal butane 50 ml/min, and isobutane 25 ml/min.
Catalyst weight: 70.0g.
Reaction pressure: 0.1 MPa.

Preparation Example 1
The MFI zeolite was produced with reference to JP 2013-227203 A.

Amorphous aluminosilicate gel was added to an aqueous solution of tetrapropylammonium (hereinafter sometimes abbreviated as TPA) hydroxide and _sodium hydroxide and suspended. MFI type zeolite was added as seed crystals to the resulting suspension to prepare a raw material composition. The amount of seed crystals added was 0.7% by weight based on the weight of _Al2O3 and _SiO2 in the raw material composition. The by-produced ethanol was removed by evaporation.

The composition of the raw material composition is as follows:
_SiO2 / _{Al2O3 molar} ratio = 47, TPA/Si molar ratio = 0.05, Na/Si molar ratio = 0.17, OH/Si molar ratio = 0.21, _H2O /Si molar ratio = 10
The obtained raw material composition was sealed in a stainless steel autoclave and crystallized for 4 days while stirring at 115° C. to obtain a slurry mixture. The slurry mixture after crystallization was subjected to solid-liquid separation using a centrifugal settler, and the solid particles were washed with a sufficient amount of pure water and dried at 110° C. to obtain a dry powder.

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

The obtained MFI zeolite had an average particle size of 39 nm, an outer surface acid amount of 0.003 mmol/g, and an acid amount of 0.24 mmol/g.

Preparation Example 2
To 100 parts by weight of the MFI zeolite obtained in Preparation Example 1, 43 parts by weight of silica (product name Snowtex N-30G, manufactured by Nissan Chemical Industries, Ltd.), 4 parts by weight of cellulose, and 20 parts by weight of pure water were added and kneaded. The kneaded product was then formed into a cylindrical molded product having a diameter of 1.5 mm and a length of 1.0 to 7.0 mm (average length 3.5 mm). This was dried overnight at 100° C. and then calcined in air at 550° C. for 1 hour. The obtained MFI zeolite molded product had an average particle size of 35 nm, an outer surface acid amount of 0.003 mmol/g, and an acid amount of 0.20 mmol/g.

Preparation Example 3
Silver was supported on the MFI zeolite molded body obtained in Preparation Example 2 by ion exchange. 300 parts by weight of pure water and 8 parts by weight of silver nitrate were used for 100 parts by weight of the MFI zeolite molded body obtained in Preparation Example 2. Silver nitrate was dissolved in pure water to prepare an aqueous silver nitrate solution, the zeolite molded body was added, and the aqueous solution was circulated in a dark place for 6 hours using a circulation pump. After washing with pure water, the product was dried overnight at 110°C, and heated to 550°C and calcined for 6 hours to prepare a silver-containing zeolite molded body.
The obtained silver-containing zeolite shaped body had a 10-membered ring framework structure, an average particle size of 32 nm, an outer surface acid amount of 0.003 mmol/g, an acid amount of 0.19 mmol/g, and a silver content of 1.4 wt %.

Example 1
The MFI zeolite molded body obtained in Preparation Example 2 was loaded with calcium by impregnation. 3.1 g of calcium acetate was dissolved in 2.0 L of pure water, and 1,050 g of the MFI zeolite molded body was added and immersed at room temperature for 30 minutes. Then, the molded body was immersed in 2.0 L of pure water for 5 minutes. This immersion in the calcium acetate aqueous solution and pure water was repeated three times. Then, the zeolite was transferred to a magnetic dish, heated to 110°C, and dried overnight. The molded body was then heated to 550°C and calcined for 6 hours to obtain a calcium-containing zeolite molded body.

The obtained calcium-containing zeolite molded body was subjected to silver loading by impregnation method. 3.1 g of silver nitrate was dissolved in 350 ml of pure water, and 108 g of the above calcium-containing zeolite was added to the aqueous solution and immersed at room temperature for 2 hours. After washing with pure water, the zeolite was dried overnight at 110°C and calcined at 550°C for 6 hours to obtain a silver-calcium-containing MFI-type zeolite molded body.

The obtained silver-calcium-containing MFI-type zeolite had a 10-membered ring framework structure, and the mesopore distribution curve in the pore distribution curve had a peak, with the half-width of the uniform mesopore peak being 10 nm and μ = 18 nm. The pore volume of the uniform mesopores was 0.36 ml/g, and the proportion of the pore volume of the uniform mesopores to the total pore volume of the mesopores was 83%. In the powder X-ray diffraction, there was no peak in the range of 0.1 to 3 degrees, the average particle size was 28 nm, the amount of outer surface acid was 0.003 mmol/g, the amount of acid was 0.16 mmol/g, the silver content was 1.1 wt%, the calcium content was 0.3 wt%, and the silver/calcium (weight ratio) was 380/100.

The silver-calcium-containing MFI-type zeolite molded body was used as a catalyst for producing hydrocarbon compounds, and the reaction was carried out for 48 hours as described above. The average yield of each product during the reaction is shown in Table 1. The average yield of light hydrocarbon compounds (total of ethane, ethylene, propane, and propylene) was 38.7% by weight, the average yield of aromatic compounds (total of benzene, toluene, and xylene) was 38.6% by weight, and the total yield of light hydrocarbon compounds and aromatic compounds was 77.3% by weight. As a catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds, it demonstrated an excellent balance and total yield.

Example 2
The silver-containing zeolite shaped body obtained in Preparation Example 3 was subjected to calcium loading by impregnation. 0.3 g of calcium hydroxide was dissolved in 200 ml of pure water, and 105 g of the silver-containing zeolite shaped body was added and immersed at room temperature for 30 minutes. Then, the zeolite was immersed in 200 ml of pure water for 15 minutes. This immersion in the calcium hydroxide aqueous solution and pure water was repeated twice. Then, the zeolite was transferred to a magnetic dish, heated to 110°C, and dried overnight. The temperature was then raised to 550°C and calcined for 6 hours to obtain a silver-calcium-containing MFI type zeolite shaped body.

The obtained silver-calcium-containing MFI-type zeolite had a 10-membered ring framework structure, and the mesopore distribution curve in the pore distribution curve had a peak, with the half-width of the uniform mesopore peak being 10 nm and μ = 17 nm. The pore volume of the uniform mesopores was 0.36 ml/g, and the proportion of the pore volume of the uniform mesopores to the total pore volume of the mesopores was 82%. In the powder X-ray diffraction, there was no peak in the range of 0.1 to 3 degrees, the average particle size was 30 nm, the amount of outer surface acid was 0.003 mmol/g, the amount of acid was 0.18 mmol/g, the silver content was 1.4 wt%, the calcium content was 0.3 wt%, and the silver/calcium (weight ratio) was 460/100.

The silver and calcium-containing zeolite molded body was used as a catalyst for producing hydrocarbon compounds, and the reaction was carried out for 48 hours as described above. The average yield of each product during the reaction is shown in Table 1. The average yield of light hydrocarbon compounds (total of ethane, ethylene, propane, and propylene) was 35.5% by weight, the average yield of aromatic compounds (total of benzene, toluene, and xylene) was 42.4% by weight, and the total yield of light hydrocarbon compounds and aromatic compounds was 77.9% by weight. As a catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds, it demonstrated an excellent balance and total yield.

Example 3
The silver-containing zeolite shaped body obtained in Preparation Example 3 was subjected to calcium loading by impregnation. 0.3 g of calcium hydroxide was dissolved in 200 ml of pure water, and 105 g of the silver-containing zeolite shaped body was added and immersed at room temperature for 30 minutes. Then, the zeolite was immersed in 200 ml of pure water for 15 minutes. This immersion in the calcium hydroxide aqueous solution and pure water was repeated six times. Then, the zeolite was transferred to a magnetic dish, heated to 110°C, and dried overnight. The temperature was then raised to 550°C and calcined for six hours to obtain a silver-calcium-containing MFI type zeolite shaped body.

The obtained silver-calcium-containing MFI-type zeolite had a 10-membered ring framework structure, and the mesopore distribution curve in the pore distribution curve had a peak, with the half-width of the uniform mesopore peak being 10 nm and μ = 18 nm. The pore volume of the uniform mesopores was 0.35 ml/g, and the proportion of the pore volume of the uniform mesopores to the total pore volume of the mesopores was 81%. In the powder X-ray diffraction, there was no peak in the range of 0.1 to 3 degrees, the average particle size was 27 nm, the amount of outer surface acid was 0.002 mmol/g, the amount of acid was 0.15 mmol/g, the silver content was 1.4 wt%, the calcium content was 0.8 wt%, and the silver/calcium (weight ratio) was 173/100.

The silver-calcium-containing zeolite was used as a catalyst for producing hydrocarbon compounds, and the reaction was carried out for 48 hours as described above. The average yield of each product during the reaction is shown in Table 1. The average yield of light hydrocarbon compounds (total of ethane, ethylene, propane, and propylene) was 46.9% by weight, the average yield of aromatic compounds (total of benzene, toluene, and xylene) was 30.3% by weight, and the total yield of light hydrocarbon compounds and aromatic compounds was 77.2% by weight. As a catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds, it demonstrated an excellent balance and total yield.

Comparative Example 1
The silver-containing zeolite shaped body obtained in Preparation Example 3 was used as a catalyst for producing hydrocarbon compounds, and the reaction was carried out for 48 hours as described above. The average yields of each product during the reaction are shown in Table 1. The average yield of light hydrocarbon compounds (the total of ethane, ethylene, propane, and propylene) was 18.0% by weight, the average yield of aromatic compounds (the total of benzene, toluene, and xylene) was 54.6% by weight, and the total yield of light hydrocarbon compounds and aromatic compounds was 72.6% by weight.

Priority was given to the production of aromatic compounds, and the production balance and productivity between light hydrocarbon compounds and aromatic compounds was poor.

Comparative Example 2
The MFI zeolite molded body obtained in Preparation Example 2 was subjected to calcium loading by an ion exchange method. 2105 g of the MFI zeolite molded body was filled up to a length of 40 cm in a PVC pipe having an inner diameter of 10.0 cm, and 6.2 g of calcium hydroxide was dissolved in 6700 ml of pure water to prepare a 12 mmol/L calcium hydroxide aqueous solution. A circulation pump and a PVC pipe were connected using a chemical-resistant polyolefin hose, and the calcium hydroxide aqueous solution was circulated at 26 cm/min for 60 minutes. After repeating this operation twice, all of the calcium hydroxide aqueous solution was extracted, and then 6700 ml of pure water was circulated at the same flow linear velocity for 15 minutes. After repeating this pure water circulation twice, the zeolite was collected on a magnetic dish, heated to 110° C., and dried overnight to obtain a calcium-containing MFI zeolite.

The calcium content of the obtained calcium-containing MFI-type zeolite was 0.3 wt%, it had a 10-membered ring framework structure, no peaks were present in the range of 0.1 to 3 degrees in powder X-ray diffraction, the average particle size was 33 nm, the amount of outer surface acid was 0.003 mmol/g, and the amount of acid was 0.19 mmol/g.

The calcium-containing zeolite molded body was used as a catalyst for producing hydrocarbon compounds, and the reaction was carried out for 48 hours as described above. The average yield of each product during the reaction is shown in Table 1. The average yield of light hydrocarbon compounds (total of ethane, ethylene, propane, and propylene) was 36.6% by weight, the average yield of aromatic compounds (total of benzene, toluene, and xylene) was 38.3% by weight, and the total yield of light hydrocarbon compounds and aromatic compounds was 74.9% by weight.

The total yield of light hydrocarbon compounds and aromatic compounds was low, resulting in poor productivity.

Comparative Example 3
The MFI zeolite molded body obtained in Preparation Example 1 was used as a catalyst for producing hydrocarbon compounds, and a reaction was carried out for 48 hours as described above. The average yields of each product during the reaction are shown in Table 1. The average yield of light hydrocarbon compounds (the total of ethane, ethylene, propane, and propylene) was 28.3% by weight, the average yield of aromatic compounds (the total of benzene, toluene, and xylene) was 46.5% by weight, and the total yield of light hydrocarbon compounds and aromatic compounds was 74.8% by weight.

Priority was given to the production of aromatic compounds, and the production balance and productivity between light hydrocarbon compounds and aromatic compounds was poor.

The novel silver-alkaline earth metal-containing MFI-type zeolite of the present invention enables a stable production method with excellent productivity and balance for each, for example, when simultaneously producing light hydrocarbon compounds and aromatic compounds from aliphatic hydrocarbons, and is extremely useful industrially as a catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds.

Claims (6)

A silver-alkaline earth metal-containing MFI zeolite characterized by satisfying the following characteristics (i) to (v):
(i) The average particle diameter (PD) is PD≦100 nm.
(ii) The mesopore distribution curve has a peak, the half width (hw) of the peak is hw≦20 nm, the center value (μ) of the peak is 10 nm≦μ≦20 nm, and the mesopore volume (pv) of the mesopores corresponding to the peak is 0.05 ml/g≦pv.
(iii) In powder X-ray diffraction measurement at a diffraction angle of 2θ, there is no peak in the range of 0.1 to 3 degrees.
(iv) the silver content is 0.05 to 3 wt %;
(v) The alkaline earth metal content is 0.05 to 5 wt. %. The silver-alkaline earth metal-containing MFI zeolite (vi) according to claim 1, further comprising any one of the following characteristics (vi) to (viii):
(vii) the acid amount is 0.05 to 0.85 mmol/g;
(viii) The weight ratio of silver/alkaline earth metal is 100/100 to 500/100. The silver-alkaline earth metal-containing MFI type zeolite according to claim 1 or 2, characterized in that the alkaline earth metal is one or more selected from the group consisting of calcium, barium and strontium. A catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds, comprising the silver-alkaline earth metal-containing MFI type zeolite according to any one of claims 1 to 3. A method for producing hydrocarbon compounds, comprising contacting aliphatic hydrocarbons having 4 to 6 carbon atoms at 400 to 800°C in the presence of the catalyst for the simultaneous production of light hydrocarbon compounds and aromatic compounds described in claim 4 to produce C2 to C3 light hydrocarbon compounds and aromatic compounds. The method for producing hydrocarbon compounds according to claim 5, characterized in that the weight ratio of C2-C3 light hydrocarbon compounds/aromatic compounds is 80/100-180/100.