Zeolite membrane composite, method for producing the same, and method for producing methanol using the same

Abstract

To provide a zeolite membrane composite having a high methanol gas / hydrogen gas permeance ratio, a method for producing the zeolite membrane composite, and a method for producing methanol using the zeolite membrane composite.SOLUTION: A zeolite membrane composite comprises a zeolite membrane on a porous support, where the ratio of the absorption intensity at 3590±10 cm-1 to the absorption intensity at 1865±10 cm-1 in Fourier transform infrared spectroscopy is 1.7 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a zeolite membrane composite, a method for producing the same, and a method for producing methanol using the same for methanol separation. [Background technology]

[0002] Methods for producing methanol from a gas containing hydrogen and carbon monoxide (hereinafter sometimes referred to as "synthetic gas") have been known for a long time, and examples of such methods include those using copper-based catalysts (copper-zinc based catalysts, copper-chromium based catalysts). The reaction for producing methanol from synthesis gas is an equilibrium reaction, and the lower the temperature and the higher the pressure, the more advantageous it is. However, because the reaction rate slows down at lower temperatures, the typical methanol production process is carried out under harsh conditions of 200-300°C and 5-10 MPaG (or higher pressure). This consumes a great deal of energy during methanol production, and the process has many limitations in terms of equipment.

[0003] As a method for efficiently producing methanol, several methods have been proposed in which the gas composition in the reactor is shifted from the equilibrium composition by removing methanol from the reaction system, and the reaction is carried out at a conversion rate exceeding the equilibrium conversion rate.

[0004] Furthermore, Patent Documents 1 to 4 propose a method of increasing the conversion rate above the equilibrium conversion rate by installing a separation membrane in a methanol synthesis reactor and removing methanol and water from the reaction system using the separation membrane. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 9-511509 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-117726 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-174996 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-55970 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 describes a lithium ion-doped perfluorinated polysulfonic acid membrane as a methanol separation membrane. Patent Document 2 describes a porous graphite membrane, and Patent Document 3 describes a zeolite separation membrane that is an MFI-type zeolite and has a Si / Al ratio of 50 or more. Patent Document 4 describes the prevention of catalyst degradation by selectively removing water. However, while these methods were sufficient for separating carbon dioxide and methanol, they had difficulty separating hydrogen and methanol, and the permeance ratio of methanol gas to hydrogen gas was low, making further improvement a challenge. The present inventors have investigated ways to solve this problem by forming a dense, gap-free film, but have found that even if a sufficiently dense film is formed, the permeance ratio is insufficient. Therefore, an object of the present invention is to provide a zeolite membrane composite having a high methanol gas / hydrogen gas permeance ratio, a method for producing the zeolite membrane composite, and a method for producing methanol using the zeolite membrane composite. [Means for solving the problem]

[0007] To selectively allow methanol gas to permeate while blocking hydrogen gas, which has a small molecular diameter, it is necessary to separate methanol by utilizing adsorption at the solid acid sites of the zeolite membrane. The inventors focused on the cation species near the membrane surface to enhance the interaction between methanol gas and the zeolite membrane and strengthen adsorption. They found that when the cation species near the membrane's extreme surface are protons rather than sodium, adsorption of methanol, a polar molecule, is strengthened, inhibiting the permeation of gases other than methanol gas.

[0008] When utilizing adsorption at the solid acid sites of a zeolite membrane, a low Si / Al molar ratio is desirable because it increases the number of adsorption sites. However, as the Si / Al molar ratio decreases, alkali metals such as sodium and potassium and alkaline earth metals such as calcium and magnesium are incorporated as cationic species, which tends to decrease the number of protons. Therefore, the present inventors discovered that a zeolite membrane with a high proton content can be formed by supporting a certain amount of seed crystals with a low content of sodium and other elements and a high Si / Al molar ratio on a porous support and then using these seed crystals as nuclei for crystal growth. This leads to an increase in the adsorption ability of methanol gas and an improvement in the permeance ratio of methanol gas to hydrogen gas. They also discovered a manufacturing method for obtaining such a zeolite membrane, which led to the present invention.

[0009] The present invention resides in the following. [1] A zeolite membrane composite having a zeolite membrane on a porous support, which has a peak intensity of 1865±10 cm in Fourier transform infrared spectroscopy -1 Absorption intensity of 3590±10cm -1 1. A zeolite membrane composite characterized in that the absorption intensity ratio of [2] The zeolite composite membrane according to the above [1], wherein the absorption intensity ratio is 1.8 or more. [3] The zeolite composite membrane according to the above [1], wherein the absorption intensity ratio is 1.9 or more. [4] The zeolite composite membrane according to the above [1], wherein the absorption intensity ratio is 2.0 or more. [5] The zeolite composite membrane according to any one of the above [1] to [4], wherein the zeolite is any one of a CHA type, an FAU type, an MFI type, an LTA type, and an RHO type. [6] A method for producing a zeolite membrane composite by forming a zeolite membrane on a porous support, wherein the zeolite is any one of CHA type, FAU type, MFI type, LTA type, and RHO type, and seed crystals are applied to the surface of the porous support at a density of 0.011 g / cm. 2 A method for producing a zeolite membrane composite, characterized by carrying the above. [7] The method for producing a zeolite composite membrane according to the above [6], wherein the seed crystals are zeolite, and the Si / Al molar ratio of the zeolite is 50 or more. [8] The method for producing a zeolite composite membrane according to the above [6] or [7], wherein the seed crystals are zeolite, and the alkali metal / Al molar ratio of the zeolite is 0.5 or less. [9] A method for producing methanol, comprising reacting a raw material gas containing at least hydrogen and carbon monoxide and / or carbon dioxide in a reactor in the presence of a catalyst to obtain methanol, wherein the methanol produced by the reaction is extracted by permeating through the zeolite membrane composite described in any one of [1] to [5] above. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a zeolite membrane composite having a high methanol gas / hydrogen gas permeance ratio, a method for producing the zeolite membrane composite, and a method for producing methanol using the zeolite membrane composite. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram showing an example of a method for producing methanol using the zeolite membrane composite of the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing an example of a method for separating methanol from a mixed gas of methanol and hydrogen using the zeolite membrane composite of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Representative embodiments for carrying out the present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be carried out in various modified forms as long as they do not depart from the gist of the present invention.

[0013] An embodiment of the present invention is a zeolite membrane composite having a zeolite membrane on a porous support, which has a zeolite peak at 1865±10 cm by Fourier transform infrared spectroscopy (hereinafter sometimes referred to as “FT-IR”). -1 Absorption intensity of 3590±10cm -1 (hereinafter, sometimes simply referred to as "absorption intensity ratio") is 1.7 or more. Normally, zeolite is electrically neutral if all of the T atoms constituting the framework are Si, but in the zeolite constituting the zeolite membrane of the present invention, some of the Si atoms are substituted with Al, resulting in a negative charge, and cations such as Na ions or H ions (protons) are adsorbed to compensate for the charge.

[0014] The Si-(OH)-Al bond formed by proton adsorption can be analyzed by Fourier transform infrared spectroscopy, and the peak wavelength is 3590±10 cm -1 This is observed as an absorption intensity of . It is thought that if this absorption is large, it is easier to adsorb methanol. The preferential adsorption of methanol inhibits the passage of hydrogen through the zeolite membrane, resulting in a high permeance ratio of methanol gas to hydrogen gas. Infrared light is absorbed as energy depending on the bonding state of the zeolite membrane, and the absolute value of this absorption intensity varies depending on the device and measurement conditions. -1 The absorption intensity of the zeolite skeletal vibration overtone (1865±10cm -1 The intensity ratio to the absorption intensity at In view of the above, in the embodiment of the present invention, the wavelength of 1865±10 cm in Fourier transform infrared spectroscopy is -1 Absorption intensity of 3590±10cm -1 The absorption intensity ratio is 1.7 or more, and by satisfying this requirement, the permeance ratio of methanol gas to hydrogen gas becomes high.

[0015] In order to increase the permeance ratio of methanol gas / hydrogen gas, the absorption intensity ratio is preferably 1.8 or more, more preferably 1.9 or more, and even more preferably 2.0 or more. On the other hand, there is no particular upper limit to the absorption intensity ratio, but it is usually 10 or less, preferably 7 or less, and more preferably 5 or less. The absorption intensity ratio can be calculated by the following formula (1): The absorption intensity of infrared light by Fourier transform infrared spectroscopy can be measured by the method described in the Examples. Maximum peak height (3590±10cm -1 ) / Maximum peak height (1865±10cm -1 )···(1)

[0016] [Zeolite membrane composite] The structure of the zeolite membrane composite of the present invention will be described in detail below. The zeolite membrane composite of the present invention has a zeolite membrane on a porous support.

[0017] <Porous support> The porous support used in the present invention preferably has chemical stability that allows zeolite to be crystallized into a membrane on its surface. Suitable porous supports include gas-permeable porous polymers such as polysulfone, cellulose acetate, aromatic polyamide, vinylidene fluoride, polyethersulfone, polyacrylonitrile, polyethylene, polypropylene, polytetrafluoroethylene, and polyimide; sintered ceramics such as silica, α-alumina, γ-alumina, mullite, zirconia, titania, yttria, silicon nitride, and silicon carbide; sintered metals and mesh-like molded bodies such as iron, bronze, and stainless steel; and inorganic porous bodies such as glass and carbon molded bodies. Among these, inorganic porous supports such as sintered ceramics, sintered metals, glass, and carbon molded bodies are preferred as porous supports for methanol separation because of their excellent mechanical strength, deformation resistance, thermal stability, and reactivity resistance at high temperatures.

[0018] The inorganic porous support is preferably a sintered ceramic, which is a solid material whose main component or most of which is composed of inorganic non-metallic substances. As described above, preferred ceramic sintered bodies include ceramic sintered bodies containing α-alumina, γ-alumina, silica, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, etc. These may be sintered bodies of a single material, or may be sintered bodies of a mixture of two or more materials. A portion of the surface of these ceramic sintered bodies may be converted into zeolite during zeolite membrane synthesis, which increases the adhesion between the porous support and the zeolite membrane, thereby improving the durability of the zeolite membrane composite. In particular, inorganic porous supports containing at least one of alumina, silica, and mullite are more preferred because they can be easily partially zeoliteized, resulting in a stronger bond between the inorganic porous support and the zeolite, making it easier to form a dense zeolite membrane with high separation performance.

[0019] The porous support used in the present invention preferably has, on its surface (hereinafter also referred to as "porous support surface"), the action of crystallizing the zeolite formed on the porous support. The pore size of the surface of the porous support is preferably controlled. The average pore size of the porous support near the surface is usually 0.02 μm or more, preferably 0.05 μm or more, more preferably 0.1 μm or more, more preferably 0.15 μm or more, even more preferably 0.5 μm or more, particularly preferably 0.7 μm or more, and most preferably 1.0 μm or more. On the other hand, the upper limit is usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 2 μm or less. By using a porous support having a pore size in this range, a dense zeolite membrane that improves methanol separation performance can be formed. The surface of the porous support is preferably smooth, and the surface may be polished with a file or the like as needed.

[0020] The pore size of the porous support used in the present invention in the portion other than the vicinity of the porous support surface is not limited and does not need to be particularly controlled, but the porosity of the other portion is usually 20% or more, more preferably 30% or more, and usually 60% or less, preferably 50% or less. The porosity of the portion other than the vicinity of the porous support surface affects the permeation flow rate when separating gas or liquid, and when the porosity is above the above-mentioned lower limit, the permeate tends to diffuse easily, while when it is below the above-mentioned upper limit, it tends to be easier to prevent the strength of the porous support from decreasing. In addition, as a method of controlling the permeation flow rate, a porous support formed by combining porous bodies with different porosities in layers may be used.

[0021] <Zeolite membrane> The zeolite constituting the zeolite membrane used in the present invention is not particularly limited as long as it is an aluminosilicate containing aluminum, but it is preferable that the main zeolite constituting the zeolite membrane contains a zeolite having a pore structure with 12 or less oxygen-membered rings and 6 or more oxygen-membered rings. The value of n in the zeolite having n-membered oxygen rings refers to the zeolite with the largest number of oxygen atoms among the pores composed of oxygen and T elements (elements other than oxygen that make up the framework) that form the zeolite framework. For example, when pores with 12-membered oxygen rings and 8-membered oxygen rings exist, as in MOR-type zeolites, the zeolite is considered to have 12-membered oxygen rings.

[0022] Zeolites having a pore structure with 12 or less oxygen-membered rings and 6 or more oxygen-membered rings include, in accordance with the codes established by the International Zeolite Association (IZA), for example, AEI, AEL, AFI, AFG, ANA, ATO, BEA, BRE, CAS, CDO, CHA, CON, DDR, DOH, EAB, EPI, ERI, ESV, EUO, FAR, FAU, FER, FRA, HEU, GIS, GIU, GME, GOO, ITE, KFI, LEV, LIO, LOS, LTA, LTL, LTN, MAR, MEP, MER, MEL, MFI, MON, MOR, MSO, MTF, MTN, MTW, MWW, NON, NES, OFF, PAU, PHI, RHO, RTE, RTH, RUT, SGT, OD, STI, STT, TOL, TON, TSC, UFI, VNI, WEI, and YUG. It is preferable to select one of these. More preferably, it is any of the CHA type, FAU type, MFI type, LTA type, or RHO type, even more preferably the CHA type, MFI type, LTA type, or RHO type, particularly preferably the MFI type or RHO type, and most preferably the MFI type.

[0023] The thickness of the zeolite membrane is not particularly limited, but is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more. By making the thickness equal to or greater than this lower limit, the performance as a separation membrane is likely to be fully exhibited. The upper limit of the membrane thickness is preferably 30 μm or less, more preferably 20 μm or less, and most preferably 10 μm or less. By setting the thickness at this upper limit, damage to the zeolite membrane due to thermal expansion and the like can be prevented, and at the same time, sufficient transmittance can be obtained. The membrane thickness can be easily distinguished by SEM based on the difference in density between the zeolite portion and the support portion, so it can be measured by SEM observation and measuring several average locations. It is sufficient to measure five average locations and calculate the average value, and it is preferable that all five locations are within the above-mentioned range.

[0024] [Method of manufacturing zeolite membrane composite] Next, the method for producing the zeolite composite membrane of the present invention will be described. The method for producing a zeolite membrane composite of the present invention is a method for producing a zeolite membrane composite by forming a zeolite membrane on a porous support, wherein the zeolite is any one of CHA type, FAU type, MFI type, LTA type, and RHO type, and seed crystals are applied to the surface of the porous support at a concentration of 0.011 g / cm. 2 The present invention is characterized in that it carries the above. In the method for producing a zeolite membrane composite of the present invention, a method for producing a zeolite separation membrane on a commonly used porous body may be used, except that a zeolite having a high Si / Al molar ratio is used as the seed crystal, and the zeolite membrane can be supported by a dipping method, a rubbing method, a suction method, an impregnation method, etc. Here, the seed crystal serves as a nucleus for growing the crystals that constitute the zeolite membrane.

[0025] A typical production method for forming Si-(OH)-Al bonds on the surface of the zeolite membrane of the present invention and increasing the proton adsorption capacity is to use a zeolite with a high Si / Al molar ratio as a seed crystal during membrane formation. The higher the Si / Al molar ratio, the less alkali metals such as Na are contained, and the easier it is to take up protons. Specifically, the Si / Al molar ratio is preferably 50 or more, more preferably 75 or more, even more preferably 100 or more, and particularly preferably 150 or more. The upper limit is preferably 500 or less, as this makes it easier to form Si-(OH)-Al bonds. Furthermore, the molar ratio of alkali metal to Al (alkali metal / Al molar ratio) of the zeolite seed crystals is preferably 0.5 or less. If the alkali metal / Al molar ratio is 0.5 or less, the alkali metal decreases as described above, and protons are more easily incorporated. From the above viewpoints, the alkali metal / Al molar ratio is more preferably 0.3 or less, even more preferably 0.1 or less, and particularly preferably 0.05 or less. The lower limit is not particularly limited, but is preferably 0.001 or more in order to avoid unnecessary effort for removal from the viewpoint of productivity. The alkali metal is not particularly limited and may include sodium, potassium, cesium, etc. The alkali metal may also include alkaline earth metals such as magnesium and calcium.

[0026] In the production method of the present invention, it is important to use a larger amount of seed crystals than usual. Specifically, the amount of seed crystals is 0.011 g / cm on the surface of the porous support. 2 or more, preferably 0.013 g / cm 2 More preferably, 0.015 g / cm 2 The amount of support should be equal to or greater than the surface area of ​​the porous carrier. 2 Although not particularly limited, the amount of support is 0.1 g / cm 2 It is preferable to use the seed crystals in the amount of 1000 or less in order to avoid using more seed crystals than necessary and to avoid wasting them. By setting the amount of seed crystals with a high Si / Al molar ratio supported within the above range, the seed crystals are packed at a high density, and a zeolite membrane with a high proton content similar to that of the seed crystals can be formed.

[0027] [Methanol production method] The zeolite membrane composite of the present invention can be suitably used in a methanol production method. More specifically, the method is suitable for producing methanol by reacting a raw material gas containing at least hydrogen and carbon monoxide and / or carbon dioxide in a reactor in the presence of a catalyst to obtain methanol. That is, the methanol produced by the reaction permeates the above-mentioned zeolite membrane composite and is extracted in high yield. As described above, methanol is produced by reacting synthesis gas as a raw material in the presence of a catalyst. The raw gas is H2 and CO x It may contain gases other than H2 and CO x Other gases include CH4, C2H4, C2H6, C3H6, C3H8, C4H8, and C4H 10 , H2O, etc., but H2 and CO xThe content of other gases is usually 50% by volume or less.

[0028] The catalyst used in producing methanol from the raw material gas may be a known catalyst, such as a copper-based catalyst (copper-zinc-based catalyst, copper-chromium-based catalyst), a zinc-based catalyst, a chromium-based catalyst, or an aluminum-based catalyst.

[0029] FIG. 1 is a cross-sectional view showing a typical example of a reactor for producing methanol from a raw material gas. The reactor 10 has a raw material feed inlet a, a permeate gas outlet b, and a non-permeate gas outlet c, and is made of materials that can withstand the high temperature and pressure conditions in which the methanol production reaction takes place. Although only one inlet a, outlet b, and outlet c is shown in the figure, multiple outlets may be present. For example, a zeolite membrane composite 1, which is a methanol permselective membrane of the present invention, is placed in the reactor 10.

[0030] The zeolite membrane composite 1 is formed by forming a zeolite membrane on a porous support. The shape of the porous support is not limited to a tubular shape, and may be a columnar shape, a hollow columnar shape, or a hollow honeycomb shape. One end of the zeolite membrane composite 1 is sealed with a cap 12, and the other end is connected to a pipe 11. The pipe 11 and the zeolite membrane composite 1, and the cap 12 and the zeolite membrane composite 1 are connected with a bonding material. The method of connecting the zeolite membrane composite is not limited to the above, and for example, both ends may be connected to pipes to allow gas to flow inside.

[0031] A catalyst 13 is arranged around the tubular zeolite membrane composite 1. The raw material gas fed from the feed inlet a comes into contact with the catalyst 13, promoting the production of methanol. The produced methanol then permeates the zeolite membrane of the zeolite membrane composite 1, thereby producing methanol with a higher purity. Furthermore, the selective permeation of methanol through the zeolite membrane composite 1 reduces the methanol concentration in the gas that comes into contact with the catalyst 13, promoting the production of methanol.

[0032] The other end of the pipe 11 is connected to a permeate gas outlet d (not shown) of the reactor, and transfers methanol that has permeated through the zeolite membrane of the zeolite membrane composite 1 to the permeate gas outlet d. The zeolite membrane composite 1 may also be connected directly to the permeate gas outlet d of the reactor without using the pipe 11.

[0033] In this embodiment, a zeolite membrane composite formed on a support can be used as the zeolite membrane. To prepare the zeolite membrane composite, for example, a cylindrical support is prepared, and zeolite microcrystals (seed crystals) are first supported in the pores. Hydrothermal synthesis can be used to grow the zeolite, as in zeolite synthesis.

[0034] In this embodiment, a raw material gas containing at least hydrogen and carbon monoxide and / or carbon dioxide is reacted in a reactor in the presence of a catalyst to obtain methanol. While the reaction conditions are not particularly limited, the reaction temperature is preferably 200°C or higher and 300°C or lower. The reaction temperature refers to the temperature inside the reactor. Setting the reaction temperature to 200°C or higher increases the reaction rate and improves productivity. Setting the reaction temperature to 300°C or lower favors the chemical equilibrium of the reaction for obtaining methanol, thereby increasing the conversion rate even if the membrane performance is somewhat inferior. This also broadens the acceptable range of heat resistance required for the bonding material.

[0035] The methanol obtained by the above reaction permeates through the methanol selective permeable membrane (zeolite membrane composite 1) in the reactor, and the methanol is recovered from the permeated gas outlet of the reactor. The pressure inside the reactor when the produced methanol is permeated through the methanol-selective permeable membrane (zeolite membrane composite 1), i.e., the pressure (gauge pressure) on the gas supply side of the methanol-selective permeable membrane (zeolite membrane composite 1) inside the reactor, is preferably 1 MPaG or higher, more preferably 2 MPaG or higher, and is preferably 8 MPaG or lower, more preferably 5 MPaG or lower. By setting the pressure within an appropriate range, the equilibrium constraints of the reaction are reduced, the reaction rate is improved, and higher productivity is easily achieved. Furthermore, increases in the reactor manufacturing costs and the cost of pressurizing the feed gas, which would be caused by excessive pressure, can be suppressed.

[0036] Furthermore, in the reaction vessel, the methanol partial pressure (absolute pressure) on the gas supply side of the methanol permselective membrane (zeolite membrane composite 1) is preferably 0.1 MPaA or more, more preferably 0.2 MPaA or more, and preferably 6 MPaA or less, more preferably 5 MPaA or less. By setting the methanol partial pressure within this range, a sufficient amount of methanol can be obtained to permeate the membrane, and the membrane's effectiveness can be fully demonstrated. On the other hand, within this range, the durability and sealing properties required for the joint do not become higher than necessary, and joining can be carried out easily and in large quantities. The gauge pressure in the reactor can be measured using a pressure gauge installed in the reactor. The absolute pressure of methanol in the reactor varies from the upstream to the downstream of the reactor, but here, the absolute pressure of methanol in the reactor is determined by calculating the gauge pressure from the analysis results of the gas composition at the reactor outlet by gas chromatography. [Example]

[0037] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the embodiments shown in the following examples.

[0038] [Evaluation method] (1) Fourier transform infrared spectroscopy (FT-IR) measurement FT-IR measurements were carried out on the zeolites prepared in each of the Examples and Comparative Examples, and the absorption intensity ratios were calculated. (Pretreatment) Each sample was degassed at room temperature for 15 minutes and then heated to 100°C at a rate of 10°C / min. (Device) The "VERTEX 70v" manufactured by Bruker Optics was used. (Measurement conditions) Measurement temperature: 100℃ Resolution; 4cm -1 Wavenumber (measurement) range: 7500 to 600 cm -1 Detector: MCT Number of measurements: 32 (continuous measurement: data acquisition every 1 minute) Measurement method: Vacuum heating diffuse reflectance method Measurement atmosphere: Degass the inside of the environmental chamber (rotary pump) Reference: Diamond powder (measured in an Al sample container) (analysis) A single spectrum at 100 °C was extracted, and the absorbance spectrum was derived using a single spectrum of diamond (after 15 min of degassing at room temperature). -1 After subtracting a linear baseline, the data were subjected to Kubelka-Munk (KM) transformation. 3590±10cm -1 The peak of the zeolite skeletal vibration is the overtone (1865±10cm -1 The absorption intensity ratio was calculated by dividing the peak height by the peak height of the peak of the

[0039] (2) Evaluation of methanol separation through zeolite membrane composite The methanol used was manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. (99.8%), and the hydrogen gas used was CO / H2 (2 / 1) standard gas manufactured by Japan Fine Products.

[0040] Methanol separation evaluation was performed using the module shown in Figure 2. Figure 2 shows a module in which the zeolite membrane composite is a tubular body with zeolite on the surface of the tubular body. The configuration is shown below. As shown in FIG. 2, a cylindrical zeolite membrane composite 1 is housed in a pressure-resistant container 2 made of stainless steel (SUS304), and the pressure-resistant container is designed to be temperature-controllable (not shown).

[0041] One end of the zeolite membrane composite 1 is connected to a pipe 4 at a connection part 3, and the other end of the pipe 4 is connected to a stainless steel pressure-resistant vessel 2, and then, outside the pressure-resistant vessel 2, is connected to a pipe (not shown) for supplying a sweep gas. The other end of the zeolite membrane composite 1 is connected to a pipe 4' at a connection part 3', and the other end of the pipe 4' is connected to a stainless steel pressure-resistant vessel 2, and then connected to an exhaust gas pipe outside the pressure-resistant vessel 2.

[0042] The pressure inside the zeolite membrane composite 1 can be measured by a pressure gauge (not shown) installed in a pipe that supplies the sweep gas (S). The pressure vessel 2 is equipped with a pipe 5 for introducing a mixed gas as a supply gas (G) and a pipe 6 for discharging a gas that does not permeate the zeolite membrane composite 1 (hereinafter referred to as a non-permeating gas (H)). The pipe 6 is connected to a back pressure valve 7 for adjusting the pressure of the mixed gas between the surface of the zeolite membrane composite 1 and the pressure vessel, and the back pressure valve 7 is connected to an exhaust gas pipe. Each connection is airtight.

[0043] In the evaluation of methanol separation using the module shown in Figure 2, methanol is vaporized in advance in a preheater, entrained with water gas, and supplied at a constant flow rate and composition between the pressure vessel and the surface of the zeolite membrane composite 1, with the pressure of the supply gas kept constant by the back-pressure valve 7. The gas that does not permeate the zeolite membrane composite 1 is discharged through the pipe 6 as non-permeated gas (H). A sweep gas (S) is passed through the inside of the zeolite membrane composite 1, and the sweep gas (S) discharged from the pipe 4 and the gas that has permeated the zeolite membrane composite 1 (hereinafter referred to as the permeated gas (T)) are discharged from the module through the pipe 4'.

[0044] The non-permeated gas (H) and permeated gas (T) were quantitatively analyzed for each gas component using an online gas chromatograph equipped with a thermal conductivity detector (TCD) with N2 as the internal standard. The values ​​obtained after the separation temperature and gas flow rate had stabilized and the analytical results had stabilized were used. The partial pressure of each component in the module varies from upstream to downstream of the reactor of the module, but the average value of the partial pressures on the inlet and outlet sides is used. The partial pressure of each component on the outlet side was calculated using the ratio of each component determined by gas chromatography. The differential pressure of each component was calculated from the partial pressure difference between the non-permeated gas and the permeated gas.

[0045] Based on the measurement results, the permeance [mol·(m 2 ·s·Pa) -1 ] is calculated. The permeance is calculated by dividing the permeation amount per unit time per area of ​​the zeolite membrane composite that the mixed gas supplied comes into contact with by the pressure difference between the partial pressure of the gas on the supply side and the partial pressure of the gas on the permeation side for each gas component. Specifically, it can be calculated using the following formula (2): Permeance = Q / (P(supply) - P(transmission)) (2) In equation (2), Q is the permeation amount of the gas component to be calculated [mol (m 2 ·s) -1 ], and P (supply) and P (permeation) respectively represent the partial pressure [Pa] of the gas to be calculated in the supply gas and the partial pressure [Pa] of the gas to be calculated in the permeation gas.

[0046] The permeance ratio is an index representing separation performance and is calculated by the following formula (3). Permeance ratio = Permeance 1 / Permeance 2 (3) In formula (3), permeance 1 and permeance 2 represent the permeance of gas species 1 and gas species 2, respectively.

[0047] The length of the zeolite membrane composite connected to the module that was in contact with the mixed gas was set to 55 mm. A mixed gas of methanol and hydrogen (mole ratio: 86:150) was supplied as a feed gas from an upstream supply port of the module to the outside of the zeolite membrane composite in the module at 235 ml / min (0°C, 1 atm equivalent). The pressure between the module and the zeolite membrane composite was controlled by a back pressure valve installed downstream of the module, and the pressure of the mixed gas was set to 0.25 MPaG.

[0048] N2 was passed through the zeolite membrane composite as a sweep gas at 97 Nml / min (0°C, 1 atm equivalent), and the gas that permeated the zeolite membrane composite was carried along with it and discharged from the module. Table 2 shows the ratio of permeance of permeated methanol to hydrogen when the module temperature was set to 200°C and 250°C, as well as the permeance of methanol.

[0049] Example 1 (Raw material mixture for hydrothermal synthesis) 2.8 g of 97% by mass sodium hydroxide (Hayashi Pure Chemical Industries, Ltd., granular) and 154.3 g of demineralized water were mixed, to which 0.17 g of sodium aluminate (Kishida Chemical Co., Ltd., containing 62.2% by mass of Al2O3) was added and stirred at 50°C for 30 minutes. 19.4 g of colloidal silica (Nissan Chemical Industries, Snowtex 40) was added, and the mixture was stirred at 50°C for 4 hours to prepare a raw material mixture for hydrothermal synthesis. The composition (molar ratio) of this raw material mixture for hydrothermal synthesis was SiO2 / Al2O3 / NaOH / H2O = 1 / 0.008 / 0.54 / 70.

[0050] (Porous support) The porous support was an 8 cm alumina tube (outer diameter 12 mm, inner diameter 9 mm) manufactured by Iwao Porcelain Industries Co., Ltd., which had been washed by flowing demineralized water and then dried.

[0051] (Seed crystal dispersion) MFI type zeolite (NH type, Si / Al molar ratio = 165, Na / Al molar ratio = 0.01) was ground in a mortar, and the seed crystals were dispersed in water to a seed crystal concentration of 0.15 mass % to prepare a seed crystal dispersion.

[0052] (Production of Zeolite Membrane Composite) The porous support was immersed in the above-mentioned seed crystal dispersion for 60 seconds, and then dried at room temperature for 30 minutes and at 70°C for 30 minutes to attach the seed crystals to the porous support. The mass of the attached seed crystals was approximately 0.0045 g, which was 0.015 g / cm per porous support surface area (external surface area of ​​the tube). 2 By this method, three porous supports with seed crystals attached were prepared. The three porous supports with attached seed crystals were each immersed vertically in a Teflon® inner tube containing the above-mentioned hydrothermal synthesis raw material mixture. The autoclave was then sealed and heated to 180°C in a thermostatic chamber over 5 hours, followed by 15 hours of static heating under autogenous pressure. After the predetermined time had elapsed, the porous support-zeolite membrane composite was removed from the reaction mixture, washed, and then refilled with demineralized water and heated in the autoclave at 120°C for 20 hours. After the predetermined time had elapsed, the porous support-zeolite membrane composite was removed from the demineralized water and dried at 100°C for 3 hours to obtain an MFI zeolite membrane composite. The results of FT-IR analysis of this zeolite membrane composite are shown in Table 1. The mass of the zeolite membrane on the porous support was 0.11 g. Furthermore, methanol was produced by the above method, and the permeance (amount of permeation) of methanol (MeOH) and hydrogen (H2) was measured, and the permeance ratio was calculated. The results are shown in Table 2. The air permeability of the zeolite membrane composite at 50 Torr was 0 cm 3 / min.

[0053] <Comparative Example 1> (Raw material mixture for hydrothermal synthesis) 2.8 g of 97% by mass sodium hydroxide (Hayashi Pure Chemical Industries, Ltd., granular) and 154.3 g of demineralized water were mixed, to which 0.17 g of sodium aluminate (Kishida Chemical Co., Ltd., containing 62.2% by mass of Al2O3) was added and stirred at 50°C for 30 minutes. 19.4 g of colloidal silica (Nissan Chemical Industries, Snowtex 40) was added, and the mixture was stirred at 50°C for 4 hours to prepare a raw material mixture for hydrothermal synthesis. The composition (molar ratio) of this raw material mixture for hydrothermal synthesis was SiO2 / Al2O3 / NaOH / H2O = 1 / 0.008 / 0.54 / 70.

[0054] (Porous support) The porous support was an 8 cm alumina tube (outer diameter 12 mm, inner diameter 9 mm) manufactured by Iwao Porcelain Industries Co., Ltd., which had been washed by flowing demineralized water and then dried.

[0055] (Seed crystal dispersion) MFI type zeolite (NH type, Si / Al molar ratio = 165, Na / Al molar ratio = 0.01) was ground in a mortar, and seed crystals were dispersed in it so that the seed crystal concentration was 0.15 mass %, to prepare a seed crystal dispersion.

[0056] (Production of Zeolite Membrane Composite) The porous support was immersed in the above-mentioned seed crystal dispersion for 10 seconds, and then dried at room temperature for 30 minutes and at 70°C for 30 minutes to attach the seed crystals to the porous support. The mass of the attached seed crystals was approximately 0.0030 g, and the ratio of the surface area of ​​the porous support to the seed crystals was 0.010 g / cm. 2 By this method, three porous supports with seed crystals attached were prepared. Three porous supports with attached seed crystals were immersed vertically in Teflon® inner tubes containing the above-mentioned hydrothermal synthesis raw material mixture. The autoclave was sealed and heated to 180°C in a thermostatic chamber over 5 hours, followed by 15 hours of static heating under autogenous pressure. After the predetermined time had elapsed, the porous support-zeolite membrane composite was removed from the reaction mixture, washed, and then refilled with demineralized water and heated in the autoclave at 120°C for 20 hours. After the predetermined time had elapsed, the porous support-zeolite membrane composite was removed from the demineralized water and dried at 100°C for 3 hours to obtain an MFI zeolite membrane composite. The results of FT-IR analysis of this zeolite membrane composite are shown in Table 1. The mass of the zeolite membrane on the porous support was 0.11 g. Furthermore, methanol was produced by the above method, and the permeance (amount of permeation) of methanol (MeOH) and hydrogen (H2) was measured, and the permeance ratio was calculated. The results are shown in Table 2. The air permeability of zeolite membrane composite 1 at 50 Torr was 0 cm 3 / min.

[0057] [Table 1]

[0058] [Table 2]

[0059] As described above, in both the examples and the comparative examples, -1 An absorption peak attributed to the Si-(OH)-Al bond was observed around 1000 nm. When the peak height was corrected according to formula (1) and compared, the value exceeded 2 in Example 1, which had a high methanol / hydrogen permeance ratio, indicating that the amount of protons adsorbed on the zeolite membrane surface was significantly large. It was also revealed that a high methanol / hydrogen gas permeance ratio could be obtained by using such a zeolite membrane composite. [Industrial Applicability]

[0060] By using the zeolite membrane composite of the present invention, a high methanol gas / hydrogen gas permeance ratio can be obtained during methanol production. Therefore, the zeolite membrane composite of the present invention is a technology of great industrial value as a zeolite separation membrane that can obtain a high methanol gas / hydrogen gas permeance ratio. [Explanation of symbols]

[0061] 1 Zeolite membrane composite 2. Pressure vessel 3, 3' Connection between zeolite membrane composite and piping 4, 4' piping 5. Piping for introducing supply gas 6 Piping 7 Back pressure valve S sweep gas G Supply gas T permeable gas H Non-permeable gas 10. Reactor 11 Piping 12 Caps 13 Catalyst a Raw material feed b Permeate gas outlet c Non-permeate gas outlet

Claims

1. A zeolite membrane composite having a zeolite membrane on a porous support, which has a peak intensity of 1865±10 cm in Fourier transform infrared spectroscopy －1 Absorption intensity of 3590±10 cm －１ 1. A zeolite composite membrane, characterized in that the absorption intensity ratio of

2. The zeolite composite membrane according to claim 1 , wherein the absorption intensity ratio is 2.0 or more.

3. 3. The zeolite composite membrane according to claim 1, wherein the zeolite is any one of a CHA type, an FAU type, an MFI type, an LTA type, and an RHO type.

4. A method for producing a zeolite membrane composite, in which a zeolite membrane is formed on a porous support, the zeolite being any one of a CHA type, an FAU type, an MFI type, an LTA type, and an RHO type, and seed crystals are applied to the surface of the porous support at a concentration of 0.011 g / cm ２ A method for producing a zeolite membrane composite, characterized by carrying the above.

5. 5. The method for producing a zeolite composite membrane according to claim 4, wherein the seed crystals are zeolite, and the zeolite has a Si / Al molar ratio of 50 or more.

6. 6. The method for producing a zeolite composite membrane according to claim 4, wherein the seed crystals are zeolite, and the zeolite has an alkali metal / Al molar ratio of 0.5 or less.

7. A method for producing methanol, comprising reacting a raw material gas containing at least hydrogen and carbon monoxide and / or carbon dioxide in the presence of a catalyst in a reactor to obtain methanol, comprising: A method for producing methanol, wherein methanol produced by the reaction is extracted by permeating through the zeolite membrane composite of claim 3.

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