JP2016010759A - Aromatic compound or acid separation membrane and separation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation membrane of an aromatic compound or an acid having a high total permeation flux.SOLUTION: A separation membrane of an aromatic compound or an acid is obtained by supplying diphenyl dimethoxysilane to base material to make a film at vapor deposition temperatures of 60°C-400°C.

Description

  The present invention relates to an aromatic compound or acid separation membrane and a separation method.

Aliphatic / aromatic hydrocarbon separation is an important separation process in the petroleum refining process, but efficient separation is generally difficult due to the close azeotropic point. Membrane separation is one of efficient separation methods. As an example of a separation system, an aromatic benzene and an aliphatic cyclohexane pervaporation (PV) method is known. Benzene and cyclohexane have close boiling points, and there are many reports on separation using polymer membranes. A membrane containing dinitrophenyl in cellulose acetate, a polymer, has been reported to have a high benzene selectivity at 70 ° C, with a benzene selectivity of 103 and a benzene permeation flux of 1.0 × 10 ^-2 kg m ^-2 h ^-1 ( Non-patent document 1). On the other hand, as an inorganic membrane, NaY zeolite membrane is reported to have a benzene selectivity of 13 and a benzene permeation flux of 8.2 × 10 ⁻² kg m ⁻² h ⁻¹ (Non-patent Document 2). In addition, there is an example in which H-β-zeolite containing Rh is introduced into polyvinyl chloride, resulting in a benzene selectivity of 26 and a benzene permeation flux of 3.9 × 10 ⁻² kg m ⁻² h ⁻¹ (Non-patent Document 3). . Thus, it seems that the development of inorganic membranes with excellent solvent resistance is important for organic matter separation such as benzene / cyclohexane system. As a method for forming an amorphous silica film, a chemical vapor deposition (CVD) method (Non-Patent Document 4) and a sol-gel method (Non-Patent Document 5) are attracting attention. In recent years, studies have been made to control the pore diameter by using a silica-organic composite material as a silica source during silica film formation (Non-Patent Documents 6 and 7). There is a report of a film having an N ₂ / SF ₆ transmittance ratio of 530 by the O ₃ counter diffusion CVD method using PrTMOS (propyltrimethoxysilane) as a silica source (Non-patent Document 7). Using this technology, Non-Patent Document 8 discloses that the deposition temperature is 320 ° C., the O ₃ flow rate is 0.4 L min ^{−1, the} benzene / cyclohexane selectivity is 113, and the total permeation flux is 2.2 × 10 ⁻⁴ kg m ^−2. It is described that h- ¹ and a benzene permselective membrane were obtained. However, the permeation flux is low. In addition, high transmission performance with H ₂ / SF ₆ transmittance ratio 6800 and N ₂ / SF ₆ transmittance ratio 45 by DPhDMOS (diphenyldimethoxysilane) as a silica source at 300 ° C O ₂ system opposite diffusion CVD method. A film has also been reported (Non-Patent Document 9), and it is reported that the film after vapor deposition is a silica film containing no organic substance (Fig. 6 (b) of Non-Patent Document 9).

  Concentration of acetic acid and sulfuric acid is performed by an evaporation method, and energy efficiency is required. We focused on reverse osmosis as an efficient dehydration method. The reverse osmosis membranes in practical use are only polymer membranes and are difficult to use in harsh separation systems. Therefore, development of reverse osmosis membranes using inorganic materials is expected. As for the present inorganic reverse osmosis membrane, separation of sodium chloride using a zeolite membrane has been reported (Non-patent Document 10).

The present inventors have developed a silica composite film by a counter diffusion CVD method. So far, the ozone concentration at the time of vapor deposition was changed and the application to the reverse osmosis separation of the silica membrane was examined. By reverse osmosis separation of an aqueous sodium chloride solution, high reverse osmosis performance was obtained with a total permeation flux of 1.7 kg m ⁻² h ⁻¹ and a Na ion rejection of 94.2% (Non-patent Document 11). By applying this to reverse osmosis separation of sulfuric acid, a high permeation performance with a total permeation flux of 0.33 kg m ⁻² h ⁻¹ and a rejection of 97.8% was obtained (Non-patent Document 12). However, the permeation flux is low.

Kusumocahyo, S. P., T. Ichikawa, T. Shinbo, T. Iwatsubo, M. Kameda, K. Ohi, Y. Yoshimi, T. Kanamori; J. Membr. Sci., 253, 43-48 (2005) You, Z., B. Li and J. Wang .; Petrochemical Technology, 36, 804-807 (2007) Zhang, X., L. Qian, H. Wang, W. Zhong and Q. Du; Sep. Purif. Technol., 63, 434-443 (2008) Nomura, M., K. Ono, S. Gopalakrishnan, T. Sugawara and S. Nakao; J. Membr. Sci., 251, 151-158 (2005) Tsuru, T., T. Morita, H. Shintani, T. Yoshioka and M. Asaeda; J. Membr. Sci., 316, 53-62 (2008) Nomura, M., T. Nagayo and K. Momma; J. Chem. Eng. Jpn., 40 (13), 1235-1241 (2007) Nomura, M., K. Momma, Y. Negishi, E. Matsuyama and S. Kimura; 'Desalin. Water Treat., 17, 288-293 (2010) Emi Matsuyama, Yuka Kimura, Keita Monma, Keisuke Utsumi, Keisuke Miyake, Takashi Kawamoto, Ryosuke Kuronuma, Mikihiro Nomura, Proceedings of Chemical Engineering, 39 (2), 98-103 (2013) Ohta, Y., K. Akamatsu, T. Sugawara, A. Nakao, A. Miyoshi and S. Nakao; J. Membr. Sci., 315, 93-99 (2008) Lu J., N. Liu, L.g Li, R. Lee; Sep. Purif. Tech., 72, 203-207 (2010) Ayumi Ikeda, Takashi Kawamoto, Emi Matsuyama, Keisuke Utsumi, Masaki Sugimoto, Masato Yoshikawa, Mikihiro Nomura, Membrane Society of Japan, Membrane Symposium 2012, P-9, (2012) Ayumi Ikeda, Emi Matsuyama, Takehide Kodaira, Makoto Komatsuzaki, Misa Sasaki, Kotone Ohura, Mikihiro Nomura, 79th Annual Meeting of the Chemical Society of Japan, SB2P25, (2014)

As described above, conventionally, as a silica source for a silica-based film, one having a linear alkyl group such as PrTMOS or PhTMOS (phenyltrimethoxysilane) having one phenyl group has been used. Moreover, when DPhDMOS was used as a silica source, it was reported that no silica remained and a silica film was formed (Non-patent Document 9; Fig. 6 (b)). PV separation of benzene / cyclohexane system at PrTMOS film or (total flux ^{2.2 × 10 -4 kg m -2 h} -1), reverse osmosis separation of aqueous sodium chloride solution PhTMOS film (total flux 0.33 kg m ^{- 2} h ^-1 ), but the total permeation flux was not sufficient in all cases. An object of the present invention is to provide an aromatic compound or acid separation membrane having a high total permeation flux. Still another object of the present invention is to provide a method for separating an aromatic compound or an acid using the above separation membrane.

  The present inventor has attempted to develop a diphenyl film using diphenyldimethoxysilane for the purpose of solving the above problems. The inventors of the present invention have focused on a chemical vapor deposition (CVD) method as a film forming method, manufactured a silica composite film by using diphenyldimethoxysilane as a silica source, and prepared an aromatic-aliphatic As a result of evaluating separation performance by pervaporation of benzene / cyclohexane as a separation, it was found that the separation performance is high, and that the separation performance is also high as an acid separation membrane. The present invention has been completed based on these findings. That is, the aspect of the present invention relates to the following.

(1) An aromatic compound or acid separation membrane comprising a membrane obtained by supplying diphenyldimethoxysilane to a substrate and forming a film at a deposition temperature of 60 ° C to 400 ° C.
(2) The aromatic compound or acid separation membrane according to (1), wherein the substrate is an alumina porous body.
(3) The aromatic compound or acid according to (1) or (2), wherein the film is formed by a counter diffusion chemical vapor deposition method in which ozone is supplied from one of the substrates and diphenyldimethoxysilane is supplied from the other of the substrates. Separation membrane.
(4) The aromatic compound or acid separation membrane according to any one of (1) to (3), wherein the deposition temperature in film formation is 270 to 360 ° C.
(5) The aromatic compound or acid separation membrane according to any one of (1) to (4), wherein the aromatic compound is benzene.
(6) A method for separating an aromatic compound or an acid using the aromatic compound or acid separation membrane according to any one of (1) to (5).

  According to the aromatic compound or acid separation membrane of the present invention, the aromatic compound or acid can be efficiently separated.

FIG. 1 shows an outline of the counter diffusion CVD method. FIG. 2 shows a CVD / permeation test apparatus. FIG. 3 shows the thermal decomposition behavior of phenyltrimethoxysilane (PhTMOS) powder and diphenyldimethoxysilane (DPhDMOS) powder by TG. FIG. 4 shows the ozonolysis behavior of phenyltrimethoxysilane (PhTMOS) powder and diphenyldimethoxysilane (DPhDMOS) powder by FT-IR. FIG. 5 shows the deposition temperature dependence of a single component gas permeation test of a phenyltrimethoxysilane (PhTMOS) film. FIG. 6 shows the deposition temperature dependence of a single component gas permeation test for a diphenyldimethoxysilane (DPhDMOS) film. FIG. 7 shows the benzene / cyclohexane PV test results. FIG. 8 shows an apparatus for a reverse osmosis test.

Embodiments of the present invention will be described below.
The separation membrane of the present invention is a membrane obtained by supplying diphenyldimethoxysilane to a substrate to form a membrane. Diphenyldimethoxysilane is a compound represented by the following structure.

  The substrate is not particularly limited as long as diphenyltrimethoxysilane can be formed, but a porous ceramic substrate is preferable. For example, as a material of the porous ceramic substrate, alumina (γ-alumina or the like) is preferable. ), Silica, silica-zirconia, silica-nickel, silica-copper, silica-cobalt, alumina-gallium oxide, alumina-lanthanum oxide, alumina-lanthanum oxide-gallium oxide, and the like.

  When a porous γ-alumina capillary is used, the average pore diameter is preferably 1 to 100 nm, more preferably 1 to 10 nm. Here, the average pore diameter can be measured with a commercially available palm porometer.

  The method for forming the diphenyldimethoxysilane in the present invention is not particularly limited, but the film formation can be preferably carried out by the counter diffusion CVD method. According to the counter diffusion CVD method, diphenyldimethoxysilane can be uniformly deposited on a substrate. The counter diffusion CVD method is a method of supplying two reactive species from both sides of a substrate as shown in FIG. The diphenyldimethoxysilane film is formed so as to close the pores of the substrate. Since the diffusion of the raw material is controlled by the deposited silica, it is possible to perform a homogeneous treatment, thereby forming a homogeneous silica film.

  As an example of the present invention, ozone may be supplied from one of the substrates such as a porous γ-alumina capillary, and diphenyldimethoxysilane may be supplied from the other of the substrates to form a film by the counter diffusion CVD method. it can.

  The deposition temperature of diphenyldimethoxysilane in the film formation described above is 60 ° C to 400 ° C, preferably 150 to 400 ° C, preferably 180 to 400 ° C, more preferably 270 to 360 ° C, and even more preferably. Is 270 to 320 ° C, particularly preferably 290 to 310 ° C.

  The separation membrane of the present invention can be used to separate aromatic compounds or acids. The kind of aromatic compound is not specifically limited, For example, benzene, toluene, xylene, naphthalene etc. can be mentioned. The kind of acid is not particularly limited, and may be either an inorganic acid or an organic acid, and may be either a strong acid or a weak acid. Examples of the inorganic acid include sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, fluorosulfonic acid, phosphoric acid, and boric acid, but are not particularly limited. Examples of organic acids include acetic acid, oxalic acid, formic acid, propionic acid, malic acid, citric acid, tartaric acid, gluconic acid, glycolic acid, lactic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid , Trifluoromethanesulfonic acid, phenolsulfonic acid and the like, but are not particularly limited.

According to the present invention, a membrane obtained by supplying the above-mentioned diphenyldimethoxysilane to a substrate and producing it at a deposition temperature of 60 ° C. to 400 ° C. for the production of an aromatic compound or acid separation membrane. Use is provided.
Furthermore, according to the present invention, there is provided a method for separating an aromatic compound or an acid using an aromatic compound or acid separation membrane comprising a membrane obtained by forming a film by supplying diphenyldimethoxysilane to a substrate. Is done.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not particularly limited by the following examples.

Example 1 Production of Separation Membrane FIG. 2 shows a schematic diagram of a counter diffusion CVD apparatus. The CVD and permeation test equipment consists of a reactor, electric furnace, ribbon heater, temperature controller, gas supply / control part, bubbler, soap film flow meter, pressure sensor, vacuum pump, and cold trap. SUS was used for the piping.

Membrane modules and membranes were sealed using O-rings with Swagelok Ultratoll processed. An electric furnace was installed at the center of the membrane module, the temperature was controlled by a temperature controller, and the temperature was measured by a thermocouple inserted in the module.
The ribbon heater was wound to prevent the silica source from condensing before reaching the reactor. When supplying the silica source, it was heated to 140 ° C. The unreacted silica source was recovered with a cold trap so that no toxic silica source was released into the atmosphere.

An N ₂ bubbler was connected to supply the silica source from the outside of the membrane, and a line supplying O ₂ and O ₃ was connected to the inside of the membrane. Each was supplied at atmospheric pressure. N ₂ and O ₂ required for film formation were electronically controlled using a mass flow controller, and H ₂ , N ₂ , and SF ₆ gases for permeation tests were adjusted by control with a needle valve.
A pressure gauge was installed in the line outside the membrane. This is for monitoring when the piping is blocked by supplying the silica source to the line outside the membrane.
Unreacted gas is exhausted to the draft inside and outside the membrane.

A porous γ-alumina capillary (manufactured by NOK: total length 60 mm, effective portion 40 mm, pore diameter 4 nm) was used as a substrate. Both sides of the substrate were sealed with Viton O-rings. The applied voltage of an O ₃ generator (ZOS-YB-6G, manufactured by Shoken) was 100 V, and ozone was supplied to the inside of the substrate as an oxidizing agent. Diphenyldimethoxysilane (DPhDMOS) (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a silica source, and was bubbled with nitrogen at 125 ° C. and distributed outside the substrate. Deposition temperature is 150-450 ° C (150 ° C, 180 ° C, 210 ° C, 240 ° C, 270 ° C, 300 ° C, 320 ° C, 340 ° C, 360 ° C, 390 ° C, 420 ° C, 450 ° C), and the evaporation time is 90 ° C. Minutes.

Example 2: Analysis of decomposition behavior For analysis of decomposition behavior, a powder obtained by hydrolyzing DPhDMOS was used. O ₃ was introduced into a quartz tube (diameter 2 mm) and treated at 180 ° C. to 360 ° C. for 90 minutes. Evaluation was performed using thermogravimetry (TG-50, manufactured by Shimadzu Corporation) and infrared absorption (FTIR-8400S manufactured by Shimadzu Corporation).

  In FIG. 3, the thermogravimetric measurement result of PhTMOS powder and DPhDMOS powder is shown. The weight change was measured while increasing the temperature in steps of 120 ° C, 180 ° C, 240 ° C, 300 ° C, 350 ° C, and 400 ° C. It shows the decomposition behavior of phenyl groups on physically adsorbed water and silica. The PhTMOS powder had a large weight loss at 120 ° C. On the other hand, the weight loss of DPhDMOS powder was slight. It can be seen that DPhDMOS powder has more phenyl groups and a hydrophobic surface. In addition, the weight loss at 240 ° C. was smaller than that of the DPhDMOS powder compared to the PhTMOS powder. It is suggested that the phenyl group derived from DPhDMOS powder has high thermal stability.

FIG. 4 shows the FT-IR measurement results of the PhTMOS powder and DPhDMOS powder after thermal O ₃ treatment. The horizontal axis represents the heat O ₃ treatment temperature, and the vertical axis represents the rate of decrease in the amount of absorption when the IR absorption amount due to the phenyl group before the heat O ₃ treatment is 1. When the vertical axis is 1, it indicates that the phenyl group is not decomposed by thermal O ₃ treatment, and when the vertical axis is 0, it indicates that all the phenyl groups are decomposed. At the time of thermal O ₃ treatment at a low temperature of around 200 ° C, the value of DPhDMOS powder shows a very high value of around 0.7. The decomposition behavior of phenyl groups on silica suggests a high residual amount of phenyl groups when derived from DPhDMOS powder. At any thermal O ₃ treatment temperature, the residual amount of phenyl groups derived from the DPhDMOS powder is large, and it can be said that the thermal decomposition behavior shown in FIG. From the results shown in FIG. 4, it can be seen that the DPhDMOS powder has carbon remaining after heat treatment.

Example 3: Single component permeation test for H ₂ , N ₂ , SF ₆
The single component permeation test for H ₂ , N ₂ , and SF ₆ was performed at a deposition temperature for films deposited at 270 ° C. or lower, and at 270 ° C. for films deposited at 270 ° C. or higher. The transmittance was measured using a pressure change method or a pressure method.

5 and 6 show single component gas permeation tests of the PhTMOS film and the DPhDMOS film. The horizontal axis is the deposition temperature during film formation. The value of the H ₂ / N ₂ transmittance ratio and the N ₂ / SF ₆ transmittance ratio in the vicinity of 300 ° C. could not be found to be significantly different between the PhTMOS film and the DPhDMOS film. It was shown that the DPhDMOS film shows high separation in the case of 180 ° C deposition and low temperature deposition. From the results of the single component transmission test, it can be said that the DPhDMOS film featured under deposition conditions at a low temperature of about 180 ° C.

Example 4: Pervaporation (PV) test A pervaporation (PV) test was performed by placing 50 mass% of a benzene and cyclohexane mixture on the membrane supply side. The PV test was performed according to the following procedure. The temperature of the membrane part was controlled at 20 ° C. or 60 ° C. and kept at a constant temperature. The permeation side of the membrane was depressurized with a vacuum pump. A permeate was collected by placing a liquid nitrogen trap between the membrane and the vacuum pump. The permeation flux was calculated from the permeation time and the weight collected in the liquid nitrogen trap. The permeate concentration was analyzed by gas chromatography (GC8-A, Shimadzu Corporation: SHIN CARBON A).

FIG. 7 shows the benzene / cyclohexane PV test results of the PhTMOS film, DPhDMOS film, and PrTMOS film. The square points are the transmission test results of the DPhDMOS film. As a result, we succeeded in developing a membrane with a separation factor of 53 and a total permeation flux of 5.6 × 10 ⁻³ kg m ⁻² h ⁻¹ and a high total permeation flux compared to the conventional PrTMOS membrane.

Example 5: Sulfuric acid reverse osmosis separation test As an evaluation of the reverse osmosis performance of the membrane, a reverse osmosis test with sulfuric acid was performed.
An acid permeation test was performed, and the hydrogen ion concentrations of the obtained permeate and the supply liquid were measured, and the sulfate ion rejection was calculated. The reverse osmosis test was performed using the apparatus shown in FIG. A high pressure pump for liquid chromatography (L-6300 type intelligent pump, manufactured by Hitachi High-Tech Fielding) was used, the pressure difference was adjusted by the back pressure valve, and the supply liquid was circulated.

(1) Acid permeation test
A 100 mg / L sulfuric acid solution was prepared and used as the feed solution. The feed solution is placed in a 500 mL beaker and constantly stirred at 300 (280-320) rpm so that the concentration gradient is constant.
Insert a non-porous glass tube instead of a membrane, operate the pump, circulate the supply liquid for about 5 minutes, and keep the sulfuric acid concentration in the device constant. After circulation, take 50 mL of the supply liquid. Measure the weight of the screw tube with a precision electronic balance. Replace the non-porous glass tube with the membrane to be measured. The pump is operated, the supply volume is 10.0 mL, and the differential pressure is adjusted to 3.0-6.0 MPa with the back pressure valve. Adjust the differential pressure slowly to avoid damaging the membrane. Be especially careful when adjusting the pressure at 4.0 MPa or higher. The time when the first drop permeated was taken as the measurement start time, and the screw tube was placed so that the permeated liquid could enter. When 1 mL (permeable volume of hydrogen ion) of permeate has accumulated in the screw tube, replace the screw tube or end the measurement. The measurement end time is the moment when one drop of the permeate drops. Adjust the back pressure valve to reduce the pressure to 0 MPa and stop the pump operation. Take 50 mL of the feed solution. Remove the membrane and replace with a non-porous glass tube. Prepare a beaker with 400 mL of pure water on the supply side and an empty beaker on the permeate side. Operate the pump, circulate pure water, and clean the equipment.

(2) Measurement of sulfuric acid concentration by ion meter A pH / conductivity meter (PCWP10, manufactured by AS ONE Co., Ltd.) was used to measure the sulfuric acid concentration of the supply liquid and permeate. The procedure for measuring the sulfuric acid concentration is shown below. 1.00 mL of each of the feed solution and permeate was collected and diluted with 49.0 mL of pure water. A pH / conductivity meter was immersed in this solution, and the pH was measured. The measured values were recorded every 1 minute, and the average value of the three points was taken as the pH of the sulfuric acid aqueous solution. The difference in measured values was kept within 0.01.

(3) Results In the reverse osmosis separation test of DPhDMOS membranes obtained at a deposition temperature of 270 ° C, the rejection is 73% and the total permeation flux is 1.6 kg m ^-2 h ^-1, which is higher than the conventional PhTMOS membrane. Permeation flux was shown.
From the above results, it was demonstrated that the film obtained by the O ₃ counter diffusion CVD method using DPhDMOS as a silica source contains a lot of phenyl groups and exhibits high total permeation flux.

Claims (6)

An aromatic compound or acid separation membrane comprising a membrane obtained by supplying diphenyldimethoxysilane to a substrate and forming a film at a deposition temperature of 60 ° C to 400 ° C. The aromatic compound or acid separation membrane according to claim 1, wherein the substrate is an alumina porous body. The aromatic compound or acid separation membrane according to claim 1 or 2, wherein the membrane is formed by a counter diffusion chemical vapor deposition method in which ozone is supplied from one of the substrates and diphenyldimethoxysilane is supplied from the other of the substrates. The aromatic compound or acid separation membrane according to any one of claims 1 to 3, wherein a deposition temperature in film formation is 270 to 360 ° C. The aromatic compound or acid separation membrane according to any one of claims 1 to 4, wherein the aromatic compound is benzene. A method for separating an aromatic compound or an acid using the aromatic compound or acid separation membrane according to any one of claims 1 to 5.