KR20200120029A - Method for separation of mixed gas containing ethane by ethane-selective adsorption using porous carbon structure having micropores with uniform distribution - Google Patents

Abstract

The present invention relates to: a composition for separating ethane and ethylene which comprises pores with an average diameter of within 2 nm and contains a carbon structure having a single-layer graphene pore wall as an active component; and a method of adsorption separation of an ethane/ethylene mixed gas using the same as an adsorbent. The present invention can be applied to an adsorption separation process of the ethane/ethylene mixed gas since selective adsorption of ethane is possible even at a high pressure at which a conventional separation reaction is performed.

Description

{Method for separation of mixed gas containing ethane by ethane-selective adsorption using porous carbon structure having micropores with uniform distribution}

The present invention contains pores with an average diameter of less than 2 nm and contains a carbon structure having a single-layer graphene pore wall as an active ingredient, and a composition for separating ethane and ethylene and an ethane/ethylene mixed gas using the same as an adsorbent. It is about the separation method.

Currently, in the oil refinery and petrochemical industries, the separation of hydrocarbons by carbon number is mostly performed by distillation, and the separation of olefins and paraffins in an olefin/paraffin mixture is mostly performed by distillation. The boiling point of the olefin and paraffin is very similar, and thus, a lot of energy is consumed in order to separate by distillation and a high number of distillation columns is required, so the equipment cost is high, and an adsorption separation process is being studied as an alternative to overcome this problem. . In olefin and paraffin separation, propylene/propane separation and ethylene/ethane separation are typical. In particular, since the distillation temperature of ethylene/ethane is lower than the distillation temperature of propane/propylene, the separation process for C2 consumes more energy, and thus the importance for the development of related C2 separation technology is increasing.

In the existing adsorption separation process technology, in order to obtain ethylene of high industrial value, ethylene is selectively adsorbed and separated from a mixture of ethane and ethylene, and then the adsorbed ethylene is recovered. Mainly.

For example, Korean Patent Registration No. 10-828137 discloses a method of preparing an adsorbent in which silver nitrate (AgNO ₃ ) is supported on a matrix in the form of a pellet selected from alumino silica gel and silica gel, and mixtures thereof, In U.S. Patent Registration Nos. 6,315,816 and 6,468,329, metal ions (Ag ⁺ , Cu ^+, etc.) which selectively adsorb ethylene by π bonds with ethylene as a method of manufacturing an adsorbent used in such adsorption separation process A method of loading on this wide substrate (silica gel, alumina, alumino silica gel, mesoporous material, etc.) is proposed. The metal ion-supporting silver nitrate (AgNO ₃ ) or copper chloride (CuCl ₂ ) solution is impregnated into a substrate and then dried. In addition, Korean Patent Publication No. 10-787210 proposes a method for preparing an adsorbent in which silver nitrate is supported on an alumino silica gel as an adsorbent suitable for olefin/paraffin separation.

As described above, most of the ethane/ethylene adsorption separation technology is carried out in a method of purging with nitrogen gas or vacuum desorption in order to adsorb ethylene and recover the adsorbed ethylene again. Therefore, it is necessary to obtain ethylene again from desorbed ethylene and nitrogen, or to recover ethylene from vacuum again. This requires a large amount of ethylene to be recovered, which consumes a large amount of energy, so the adsorption capacity of the adsorbent must be large and the desorption process is There is a drawback of recovering, including.

Therefore, in order to obtain ethylene, the process can be simplified by increasing the purity of ethylene by selectively adsorbing ethane contained in 50 mol% or less or in a small amount. However, conventional ethane selective adsorbents have low adsorption strength between ethane and adsorbent, so the degree of separation is low, and at high pressure, the attraction between ethylene and ethylene becomes superior to the attraction between ethane and ethane, so that the adsorption of ethylene is higher than that of ethane. This happens. Therefore, it is difficult to maintain the degree of separation even at high pressure by selectively adsorbing ethane with the existing adsorption technology.

Table 1 below shows the adsorption amount for ethane/ethylene of a series of MOFs including the ZIF series. As shown in Table 1, ZIF series and Ni (bdc) (ted) existing equilibrium selective adsorbent removable ethane except _.5 is a nitrogen or oxygen in the structure of porous carbon material or a hybrid nanoporous body is exposed to the pore wall It is adsorbed by attraction between hydrogen at the end of ethane CH part and hydrogen bonded with nitrogen or oxygen with high electronegativity in the porous material, but when adsorbed, 6 hydrogens participate in ethane and 4 hydrogens participate in ethylene. . At this time, there may be limitations in introducing useful nitrogen and oxygen into the porous structure. As shown in the adsorption conditions, it is the adsorption result only up to 100 kPa, that is, normal pressure, and the possibility of maintaining adsorption at high pressure is important because high-pressure gas is supplied in the actual process. Furthermore, in addition to the adsorption result for a single gas, ethane in the actual mixed gas It is important whether it can exhibit superior adsorption power compared to ethylene.

absorbent Ethane (mmol/g) Ethylene (mmol/g) Adsorption condition ZIF-7 1.7 0 100 kPa & 25℃ ZIF-8 2.5 1.3 100 kPa & 25℃ ZIF-69 2.2 1.8 100 kPa & 25℃ _{Ni (bdc) (ted) 0} .5 5 3.4 100 kPa & 25℃ PCN-250 5.21 4.22 100 kPa & 25℃ MIL-142A 3.8 2.9 100 kPa & 25℃ PCN-245 3.27 2.39 100 kPa & 25℃ Boron nitride 3.2 2.3 10 kPa & 38℃ MAP-49 1.42 0.85 100 kPa & 25℃ C-PDA-3 6.57 5.1 100 kPa & 25℃ C-700-3 7.2 5.9 100 kPa & 25℃ C-Fru-2-700 6.8 6.25 100 kPa & 25℃ C-Fru-3-700 7.25 6.45 100 kPa & 25℃ C-Fru-4-700 7.94 6.64 100 kPa & 25℃

As shown in Table 1, ZIF series and Ni (bdc) (ted) but _.5 including inorganic An example of using the hybrid nanoporous body at a rate detachable ethane / ethylene absorbent report, the high speed resolution for ethane Nevertheless, it has been reported that these adsorbents have so small pore size that a lot of energy is consumed for ethylene desorption.

As a result of intensive research efforts to discover an adsorbent capable of selectively adsorbing ethane compared to ethylene even at a relatively high pressure, the present inventors have produced a microporous carbon structure having a predetermined pore size formed very uniformly and manufactured using zeolite as a template. When used, ethane can be selectively adsorbed compared to ethylene, and the degree of separation can be maintained even at a relatively high pressure, confirming that it can be used as an adsorbent for ethane/ethylene separation using an adsorption separation process, and the present invention was completed.

In one aspect, the present invention provides a composition for separating ethane and ethylene, comprising as an active ingredient a carbon structure comprising pores having an average diameter of 2 nm or less, and having a single-layer graphene pore wall.

In another aspect, the present invention is an adsorbent, wherein a mixed gas containing ethane and ethylene is brought into contact with a reactor having a carbon structure including pores having an average diameter of less than 2 nm and having a single-layer graphene pore wall. It provides a method for adsorption separation of an ethane/ethylene mixed gas comprising the step.

In another aspect, the present invention includes a carbon structure having an average diameter of less than 2 nm in the adsorbent layer, a single-layer graphene pore wall, and a gas inlet on one side and a gas outlet on the other side. Thus, a mixed gas containing ethane and ethylene at a pressure of more than 0 bar and less than 20 bar containing 50 mol% or less of ethane is injected into the reactor in which the gas input from the gas inlet passes through the adsorbent layer and is discharged through the gas outlet. A first step of collecting ethylene gas whose ethane content is reduced to less than 1 mol% from the gas outlet while adsorbing; When the ethane content in the gas discharged from the gas outlet is 1 mol% or more, ethylene gas with a purity of 99 mol% or more is injected into the reactor in which the ethane is adsorbed at a pressure less than the adsorption pressure to desorb the adsorbed ethane while adsorbing ethylene. A second step of saturating the layer; And a mixed gas containing ethane and ethylene having a pressure of more than 0 bar and not more than 20 bar is injected into the reactor in which the adsorbent layer is saturated with ethylene, and ethane is resorbed while collecting ethylene gas having an ethane content of less than 1 mol% from the gas outlet. It provides a method for producing ethylene gas having a purity of 99 mol% or more, including a third step.

Hereinafter, the present invention will be described in more detail.

The present invention is a process for separating ethylene from a mixed gas containing ethane and ethylene by selective adsorption using an adsorbent, not by a conventional distillation process that consumes a lot of energy and/or cost, In the case of using a conventional ethylene selective adsorbent, it is devised to overcome the disadvantage of requiring a cumbersome and energy-consuming additional process in order to recover the adsorbed ethylene after separating ethane and ethylene by selective adsorption of ethylene. Specifically, the present invention discovers an adsorbent capable of selectively adsorbing ethane compared to ethylene, but in consideration of the fact that the separation process of the actual mixed gas proceeds at high pressure, it exhibits superior adsorption ability for ethane even at a relatively high pressure. It is based on discovering a possible adsorbent.

The composition for separating ethane and ethylene according to the present invention includes pores having an average diameter within 2 nm, and includes a carbon structure having a single layer of graphene with pore walls as an active ingredient.

For example, the composition for separating ethane and ethylene according to the present invention includes pores of an average diameter distributed in the range of 0.3 to 2 nm, and the full width at half maximum of the pore size distribution is 0.1 to 0.8 nm, and micropores of uniform size are It may include, as an active ingredient, a three-dimensional carbon structure in which the microporous pore walls are single-layer graphene, but is not limited thereto.

The term "graphene" of the present invention may mean a carbon allotrope composed of a single layer of carbon atoms arranged in a hexagonal lattice. Graphene arranged in a perfect hexagonal lattice has a planar structure, but by including a small number of pentagonal and/or heptagonal defects in the hexagonal lattice, it can have a three-dimensional structure by distortion caused at these defect sites. Planar graphene arranged in a hexagonal lattice has a high degree of stability due to densely arranged carbon atoms and SP ² orbital hybridization. That is, graphene has π electrons distributed over the entire surface, and π interaction is possible through it.

In the three-dimensional carbon structure of the present invention, π electrons exist over the entire surface area, and ethane and/or ethylene, which are small molecules including a plurality of CH bonds, can be adsorbed in one molecule through an attraction of CH π. The CH···π attraction is weaker than that of a chemical bond such as a covalent bond or an ionic bond, but an interaction equivalent to an electrostatic attraction or a hydrogen bond is possible. For example, ethylene's quadruple moment (1.50×10 ^-26 esu·cm ² ) is greater than that of ethane (0.65×10 ^-26 esu·cm ² ), whereas ethane's polarizability ( 44.7×10 ^-25 cm ³ ) is greater than that of ethylene (45.5×10 ^-25 cm ³ ) due to the higher molecular weight and larger size. Therefore, when a material having a large polarity, such as a porous material containing copper or silver ions or a porous organic-inorganic hybrid material having an unsaturated coordination site, is used as the adsorbent, ethylene having a large quadrupole moment is predominantly adsorbed. On the other hand, in the case of an adsorbent having little or no polarity on the surface, adsorption of ethane with a high polarization rate appears predominantly.

At this time, ethane containing 6 C-H bonds in one molecule may exhibit more superior adsorption power with the carbon structure of the present invention based on a numerical advantage over ethylene containing 4 C-H bonds. Compared to such ethylene, a high adsorption power for ethane can be maintained from 0.1 bar to a relatively high 10 bar, and even 50 bar.

In order to exhibit excellent adsorption power to ethane compared to ethylene as described above, not only has a small pore size in the range of 0.3 to 2 nm, but also the FWHM of the corresponding size distribution is a narrow distribution of 0.1 to 0.8 nm, that is, pores of uniform size. It is important to have. For example, if the pore size is larger than 2 nm, even if ethane is first adsorbed to the adsorption site in the adsorbent pores based on the greater number of CH ... π attraction per single molecule as described above, When ethane and/or ethylene is present in the multimolecular layer, adsorption between ethylene and ethylene becomes dominant compared to adsorption between ethane and ethane, and further, as the pressure increases, the adsorption amount of ethylene may exceed the adsorption amount of ethane. In other words, 0.3 nm to 2 nm is the predominant adsorption power of ethane to the adsorption site through CH ... π attraction, and a multi-layer ethane layer is formed through adsorption between ethane and ethane, thereby preventing the introduction of ethylene. This is the size chosen to be blocked. Therefore, in the case of using an adsorbent having such micropores, even if the pressure is slightly increased, the superior adsorption power of ethane can be maintained with respect to ethylene, and thus, selective adsorption of ethane may be possible.

As described above, not only has a micropore structure having a pore size distribution in the range of 0.3 to 2 nm, which can be used in the adsorption separation method of the present invention, and the FWHM of the corresponding size distribution is a narrow distribution of 0.1 to 0.8 nm, that is, a uniform size. A three-dimensional carbon structure having pores of can be prepared by transferring from a zeolite template providing a regular pore structure.

Specifically, the three-dimensional carbon structure, which is an active ingredient of the composition for separating ethane and ethylene according to the present invention, is an unsaturated aliphatic hydrocarbon in a zeolite containing an active metal that is an empty d-orbitial metal, It may be formed along the pore walls of the mold by chemical vapor deposition performed at 400 to 650° C. by supplying a mixed gas including a carrier gas and water vapor.

Zeolites that can be used at this time include LTL, VFI, MAZ, MEI, FAU, EMT, OFF, BEA, MOR, MFI, MPS, MEL, MTW, EUO, MTT, HEU, FER, TON, CHA, ERI, KFI, LEV, LTA or a mixed structure type thereof may be used without limitation, but is not limited thereto.

The exemplified zeolites are microporous structures having pores having a size of sub to several nm, and the zeolite ion-exchanged with a metal having an empty d-orbital electron is a material containing an unsaturated bond using an empty d-orbital, that is, A material containing an unsaturated bond injected through the attraction with the π-bond included therein can be adsorbed on the surface. For example, if an unsaturated aliphatic hydrocarbon is supplied to the material containing the unsaturated bond and carbonized while adsorbed to the ion-exchanged zeolite with a metal with empty d-orbital electrons, a carbon structure in which the pores of the zeolite are transferred can be formed. In addition, by removing the zeolite used as a template through etching, only a carbon structure in which the microporous structure of the zeolite is precisely transferred can be obtained.

Specifically, the carbon structure is formed by supplying a mixed gas containing an unsaturated aliphatic hydrocarbon, a carrier gas, and water vapor from a zeolite ion-exchanged with a metal having an empty d-orbital electron to form carbon, and wet etching using an aqueous acid solution. It can be prepared by a method comprising the step of selectively removing zeolite. The wet etching may be performed simply by immersing in an aqueous solution containing HF and/or HCl, but is not limited thereto as long as only zeolite can be selectively removed without damaging the carbon structure.

As a metal in which d-orbital electrons introduced into the zeolite for interaction with an unsaturated aliphatic hydrocarbon are vacant, lanthanum, calcium, and yttrium may be used alone or in combination. Meanwhile, ethylene or acetylene may be used as the unsaturated aliphatic hydrocarbon, but is not limited thereto, and may be appropriately selected in consideration of the pore size of the zeolite used as a template. Furthermore, an inert gas such as nitrogen or argon may be used as the carrier gas. The unsaturated aliphatic hydrocarbon and water vapor may be used in a ratio of 1:0.1 to 3, but are not limited thereto.

As described above, the three-dimensional carbon structure prepared as described above has adsorption power for ethane and/or ethylene, and thus may be used in a composition for adsorption of these gases. Therefore, for convenience of use, the step of forming may be additionally performed. At this time, the shaping may be performed before or after removing the zeolite by wet etching using an acid solution. However, since the three-dimensional carbon structure from which the zeolite, which is a template, has been removed, may be weak in strength and may be vulnerable to pressure, etc., for convenience of the process, a step of molding may be performed prior to removing the zeolite, but is not limited thereto.

Through the above-exemplified method, the carbon structure prepared by adsorbing and carbonizing an unsaturated aliphatic hydrocarbon using a zeolite ion-exchanged with a metal having an empty d-orbital electron as a template is transferred to the microporous structure of the zeolite, and has almost the same size and Not only does it provide a high specific surface area because it has micropores in the form of micropores, but most of the bonds between these carbons are made up of SP ² similar to graphene, so it can achieve superior adsorption with ethane compared to ethylene through the CH···π attraction. I can.

In addition, the present invention comprises the step of contacting a mixed gas containing ethane and ethylene to a reactor having a carbon structure including pores having an average diameter of less than 2 nm and having a single-layer graphene pore wall as an adsorbent. , Provides a method of adsorption separation of ethane/ethylene mixed gas.

As described above, including pores having an average diameter within 2 nm, for example, including pores having an average diameter distributed in the range of 0.3 to 2 nm, and the full width at half maximum of the pore size distribution is 0.1 to 0.8 nm, uniform The three-dimensional carbon structure of single-layer graphene with micropores of the size of the micropores exhibits superior adsorption ability for ethane compared to ethylene by CH π attraction due to the numerical advantage, so it is used as an adsorbent. A mixed gas of ethane/ethylene can be separated by selective adsorption of ethane.

Further, the present invention comprises a carbon structure having an average diameter of less than 2 nm in the adsorbent layer, a single-layered graphene pore wall, and a gas inlet on one side and a gas outlet on the other side from the gas inlet. A mixed gas containing ethane and ethylene at a pressure greater than 0 bar and less than 20 bar containing 50 mol% or less of ethane is injected into the reactor in which the input gas passes through the adsorbent layer and is discharged through the gas outlet to adsorb ethane. A first step of collecting ethylene gas having an ethane content of less than 1 mol% from the outlet; When the ethane content in the gas discharged from the gas outlet is 1 mol% or more, ethylene gas with a purity of 99 mol% or more is injected into the reactor in which the ethane is adsorbed at a pressure less than the adsorption pressure to desorb the adsorbed ethane while adsorbing ethylene. A second step of saturating the layer; And a mixed gas containing ethane and ethylene having a pressure of more than 0 bar and not more than 20 bar is injected into the reactor in which the adsorbent layer is saturated with ethylene, and ethane is resorbed while collecting ethylene gas having an ethane content of less than 1 mol% from the gas outlet. It provides a method for producing ethylene gas having a purity of 99 mol% or more, including a third step.

By using the above manufacturing method, high purity ethylene with high industrial applicability can be produced from a mixed gas containing 50 mol% or less of ethane together with ethylene.

The "ethylene" is a monomer used in the manufacture of polyethylene (PE), which is one of the most widely used plastics, and may be produced by steam cracking of ethane. Ethylene thus produced is provided as a mixture with unreacted ethane, and they are usually separated using a distillation method. In this case, gas such as carbon dioxide may be generated as a by-product in the reaction, but the content thereof is insufficient, and most of the by-product may be ethane. The product of the ethylene production reaction may be assumed to be a mixed gas of ethylene and ethane, and the content of ethane contained therein does not exceed the production amount of ethylene, for example, it may be a gas mixed at a molar ratio of at most 50:50, Usually, the content of ethylene exceeds the content of ethane, but the present invention is not limited thereto, and the adsorption separation method of the present invention can be applied.

For example, the second step may be performed until the ethylene content of the gas discharged from the gas outlet becomes 99 mol% or more.

Meanwhile, in the manufacturing method, after the third step, the cycle including the second step and the third step may be additionally performed one or more times. For example, by controlling the type and/or pressure of the supplied gas without a separate desorption process, the above process may be continuously performed by repeating the sequential adsorption/desorption of ethane and ethylene. Further, a gas having an ethane content of 1 mol% or more or an ethylene content of less than 99% in the gas discharged from the gas outlet may be separately recovered and re-introduced as a mixed gas in the third step to improve the ethylene content.

In order to recover high-purity ethylene gas, a means for measuring the content of ethane and/or ethylene may be additionally provided at the gas outlet of the reactor, and ethane, ethylene, or two in the gas discharged from the gas outlet may be further provided. By monitoring the content of all, it is possible to selectively recover a gas having an ethane content of less than 1 mol% or an ethylene content of 99 mol% or more.

The present invention is a uniform pore distribution having an average diameter of 2 nm or less, for example, a pore distribution having a full width of 0.1 to 0.8 nm in the range of 0.3 to 2 nm, which can exhibit ethane selective adsorption ability in a wide pressure range of 0.1 to 50 bar. A typical separation reaction by using a C5 or C7 carbon structure based on a C6 carbon structure, or a three-dimensional carbon structure including both as an adsorbent, having a micropore of one size, containing 95% or more of SP ² carbon bonds Since ethane selective adsorption is possible even at a high pressure in which this is performed, it can be applied to the adsorption separation process of an ethane/ethylene mixed gas.

1 is a diagram schematically showing a process of obtaining high-purity ethylene from an ethane/ethylene mixed gas by using the ethane superior adsorption property of a microporous carbon structure made of zeolite as a template.
FIG. 2 is a diagram showing the adsorption and desorption curves and pore size distributions of argon for a microporous carbon structure, (a) Beta-ZTC and (b) FAU-ZTC, made of a zeolite according to an embodiment.
Figure 3 is a microporous carbon structure made of a zeolite according to an embodiment as a template (a) Beta-ZTC, (b) FAU-ZTC and (c) EMT-ZTC measured using an adsorbent in ethane / ethylene It is a diagram showing the adsorption and desorption isotherms at 0 to 10 bar.
4 is a comparative example from 30° C. to normal pressure (100 kPa) for ethane/ethylene measured using (a) CuCl ₂ supported silica, (b) graphene sheet and (c) Darko activated carbon as an adsorbent. It is a diagram showing the adsorption and desorption isotherms of and (d) the adsorption and desorption isotherms from 30°C to 10 bar for ethane/ethylene measured using Darko activated carbon as an adsorbent.
FIG. 5 is a diagram showing a breakthrough curve according to a mixture composition of ethane and ethylene measured for an ethane/ethylene mixed gas using a microporous carbon structure made of zeolite as a template and Beta-ZTC according to an embodiment. .
6 is a diagram showing changes in individual gas content in the process of obtaining high-purity ethylene using an adsorption-desorption cycle prepared based on a breakthrough experiment for an ethane/ethylene mixture gas measured using Beta-ZTC as an adsorbent.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for describing the present invention in more detail, and the scope of the present invention is not limited by these examples.

Comparative example One: Darko Activated carbon

Commercially available Darco activated carbon was purchased and used as a sample of Comparative Example 1. Darko activated carbon consists of SP ² C6, but it has a characteristic that the PSD is not constant.

Comparative example 2: Graphene Sheet

A graphene sheet was purchased from Enbarotech, and was used as a sample of Comparative Example 2. Graphene sheet is also made of SP ² C6, but contains only C6 carbon structure.

Comparative example 3: copper Supported Silica adsorbent

A silica adsorbent carrying CuCl ₂ at 1% by weight was used as a sample of Comparative Example 3.

Manufacturing example 1: Lanthanum is Ion-exchanged FAU Preparation of microporous carbon structure using zeolite

After immersing FAU zeolite in 0.5 M La(NO ₃ ) ₃ aqueous solution for 20 minutes, the process of obtaining through a filter was repeated three times to prepare a lanthanum ion-exchanged FAU zeolite. The lanthanum content in the lanthanum ion-exchanged FAU zeolite was about 20% by weight. The lanthanum ion-exchanged FAU zeolite was placed in a quartz tube reactor equipped with a 15 mm disk, and the reactor was heated to 600°C under a nitrogen atmosphere. When the temperature inside the reactor reached 600° C., a mixed gas of ethylene, water vapor, and nitrogen as a carrier gas was passed through the reactor to form carbon for 3 hours. Thereafter, heat treatment was performed at 800° C. for 2 hours in a state of being treated only with nitrogen, and the reactor was cooled to room temperature. The ethylene/water vapor/nitrogen composition of the mixed gas used was 10 mol%/7 mol%, 83 mol%, and flowed at a total rate of 130 mL per minute. The point at which the reaction was terminated for 3 hours was set based on the point at which the weight of the carbon-zeolite composite no longer increased because no more carbon was deposited. A porous carbon structure was obtained by selectively removing zeolite from the prepared carbon-zeolite composite by using wet etching using a mixed aqueous solution of HF and HCl.

An isothermal adsorption and desorption graph and pore size for argon of the carbon structure prepared as described above were measured, and the results are shown in FIG. 2. As shown in FIG. 2, the carbon structure prepared by using the zeolite ion-exchanged with lanthanum as a template according to the present invention was found to have pores having an average size of 0.92 nm. The full width at half maximum (FWHM) of the peak calculated from the pore distribution graph was 0.5 nm, and it was confirmed that micropores having a very uniform size were formed.

In addition, it was confirmed that all carbon atoms constituting the prepared carbon structure had SP ² bonding properties. Specifically, it was confirmed through NMR analysis that the prepared carbon structure was a 3D microporous graphene structure. This indicates that the carbon structure of C5 and/or C7 is included in addition to the C6 carbon structure in order to have a three-dimensional structure with a curve, not a graphene sheet while having SP ² bonding properties.

Manufacturing example 2: Lanthanum is Ion-exchanged Preparation of microporous carbon structure using beta zeolite

A carbon structure was prepared in a similar manner to Preparation Example 1, except that zeolite having a beta structure was used instead of the FAU zeolite as the template. Argon adsorption was analyzed for the prepared carbon structure, and pore size distribution and FWHM were calculated therefrom. As a result, it was confirmed that the carbon structure manufactured using the beta-structure zeolite as a template was a porous structure having an average size of 0.88 nm and uniform micropores of 0.2 nm FWHM, and the BET specific surface area and micropore fraction calculated therefrom were 2540, respectively. m ² /g and 1.18 mL/g.

Manufacturing example 3: Lanthanum is Ion-exchanged EMT Preparation of microporous carbon structure using zeolite

A carbon structure was prepared in a similar manner to Preparation Example 1, except that zeolite having an EMT structure was used instead of the FAU zeolite as the template. Argon adsorption was analyzed for the prepared carbon structure, and pore size distribution and FWHM were calculated therefrom. As a result, it was confirmed that the carbon structure manufactured using the beta-structure zeolite as a template was a porous structure having an average size of 0.93 nm and uniform micropores of 0.2 nm FWHM, and the BET specific surface area and micropore fraction calculated therefrom were 2660, respectively. m ² /g and 1.12 mL/g.

Example 1: About ethane/ethylene gas of a microporous carbon structure made of zeolite Adsorption and desorption Isotherm measurement

Adsorption and desorption isotherms for ethane/ethylene using a microporous carbon structure (zeolite-templated carbon), FAU-ZTC, Beta-ZTC, and EMT-ZTC prepared by the zeolite prepared according to Preparation Examples 1 to 3 as an adsorbent Was measured. Specifically, adsorption was performed using a gravimetric analyzer manufactured by Rubotherm. Gas adsorption conditions for each of ethane/ethylene were carried out at 30° C. to 100 bar. As adsorbents, 100 mg of FAU-ZTC, Beta-ZTC and EMT-ZTC powder were each used. The prepared adsorbent was heated at 200° C. for 6 hours and cooled to 30° C. for pretreatment, and then adsorption was started. The adsorption and desorption isotherms measured for each are shown in FIG. 3. (a) to (c) are results obtained by using Beta-ZTC, FAU-ZTC, and EMT-ZTC as adsorbents, respectively. As shown in FIG. 3, the difference in adsorption amount of ethane and ethylene was shown in the entire range between 1 bar and 10 bar of adsorption pressure, which indicates that ethane and ethylene can be separated using these adsorbents in the corresponding pressure range. Show. For example, when Beta-ZTC was used as an adsorbent, the adsorption amounts of ethane and ethylene at an adsorption pressure of 10 bar were 10.6 mol/g and 8.4 mol/g, respectively, and the degree of separation at low pressure was maintained up to 10 bar. In order to more specifically confirm the separation effect due to the difference in the amount of ethane/ethylene adsorption of the microporous carbon structure, as a comparative example, an adsorption and desorption experiment under the same conditions using silica, graphene sheet or activated carbon supporting CuCl ₂ as an adsorbent. And the results are shown in FIG. 4. Specifically, as shown in FIG. 4(a), it was confirmed that the use of an adsorbent having polarity including copper ions exhibited superior adsorption power to ethylene compared to ethane. On the other hand, as shown in Figs. 4(b) and 4(c), when a conventional graphene sheet or activated carbon is used as an adsorbent, the difference in adsorption amounts of ethane and ethylene at less than 1 bar (100 kPa) was very slight. In the case of using the graphene sheet, it was confirmed that the higher the pressure, the higher the amount of ethylene adsorption was. Further, FIG. 4(d) shows an ethane/ethylene adsorption and desorption isotherm measured under increased pressure conditions up to 10 bar using Darko activated carbon as an adsorbent as a comparative example, and the adsorption and desorption isotherms for ethane and ethylene are shown. All were saturated around 2 bar, and although ethane showed a somewhat dominant adsorption power even when the pressure was increased to 10 bar, the difference was still insignificant.

Example 2: Beta- ZTC's For ethane/ethylene gas Breakthrough Curve measurement

The breakthrough curve for ethane/ethylene was measured using BEA-ZTC, which showed the best adsorption ability in Example 1. Specifically, in order to measure the breakthrough curve of ethane/ethylene, a tubular reactor was prepared and adsorption was performed. Adsorption conditions for measuring the breakthrough curve were a mixed gas of a composition containing 50:50 or 10:90 mol% of ethane and ethylene, respectively, and the pressure of the reactor was selected from 1 to 5 bar. For the breakthrough experiment, about 1 g of BEA-ZTC molded body was used as an adsorbent. Prior to the adsorption experiment, heat treatment was performed at 200° C. for 12 hours in a vacuum state. After the molded body was filled in the reactor, it was cooled to 10° C., and adsorption was initiated while flowing a mixed gas of the composition at 10 cc/min. The breakthrough curves measured for each are shown in FIG. 5.

As shown in FIG. 5, it was confirmed that adsorption separation of ethane/ethylene from the mixed gas was possible using beta-ZTC as an adsorbent. Specifically, when a mixed gas of 1:1 composition is flowed at 1 bar, the time for 99.9% of ethylene to be released while ethane is adsorbed was about 5 minutes, and when pressurized to 5 bar, the time for 99.9% of ethylene to be released was about It was about 4 minutes. On the other hand, when the 1:9 mixture gas was flowed at 1 bar, the time for 99.9% of ethylene to be released was about 6 minutes, but when pressurized at 5 bar, it was about 5 minutes. This indicates that adsorption separation of ethane/ethylene is possible from mixed gases of various compositions not only under normal pressure but also under pressure. For example, in the case of an actual process, since it is introduced into the adsorption reactor in the form of a high-pressure mixed gas, the ability to maintain adsorption separation even at high pressure is an important factor as an adsorbent for adsorption separation.

Example 3: Beta- ZTC's For ethane/ethylene gas Breakthrough And desorption experiment

Based on the results of the breakthrough experiment for ethane/ethylene using Beta-ZTC performed in Example 2, a composition gas containing 10 mol% and 90 mol% of ethane and ethylene, respectively, was used, and as an adsorbent, Beta- Using 1 g of the ZTC molded body, after heating at 200°C for 12 hours and cooling to 10°C for pretreatment, adsorption/desorption experiments were started.

Specifically, after flowing an ethane/ethylene mixture gas into the reactor equipped with the adsorbent and maintaining the pressure at 5 bar to induce selective adsorption of ethane (step (a)), ethylene was reduced to 1 bar and flowed through ethylene. The ethane was desorbed by purge (step (b)), and the mixed gas was again adsorbed while flowing at 5 bar (step (c)). At this time, the content of ethane and ethylene in the emission gas of each step was measured and shown in FIG. 6. As shown in FIG. 6, during the adsorption in step (a), ethylene occupied more than 99.9% of the discharged gas by selective adsorption of ethane in the initial stage (27 to 35 minutes). During the ethylene purge in step (b), ethane, which had been selectively adsorbed from the previous step, was desorbed (until ~17 minutes) and released. In the subsequent re-adsorption of step (c), as in step (a), ethane was selectively adsorbed until ~35 minutes, and ethylene occupied most of the exhaust gas. This indicates that high purity ethylene with high industrial applicability can be produced by purifying ethylene (purity of 99.9% or more) from a mixed gas containing a small amount of ethane in ethylene by an adsorption separation reaction using the adsorbent of the present invention. .

Specifically, as shown in FIG. 1, a method of obtaining high purity ethylene from an ethane/ethylene mixed gas using an adsorbent having superior ethane adsorption characteristics could be carried out through a three-step reaction as follows.

Step 1 : Pre-adsorption of ethylene in an adsorption tower filled with an adsorbent with superior adsorption properties of ethane

Step 2 : Ethane molecules are adsorbed to the adsorbent instead of pre-adsorbed ethylene by flowing an ethane/ethylene mixed gas (ethane content less than 50%) to be separated.

Step 3 : Recovering pre-adsorbed ethylene desorbed while being replaced by ethane in the mixed gas and high-purity ethylene containing ethylene in the mixed gas

Specifically, a process method that can be regenerated with lower energy than other processes in the adsorption process is as follows. After vacuum pretreatment at 200° C. or higher in an adsorption tower filled with an adsorbent for selectively adsorbing ethane, ethylene gas was charged. Then, when the ethane/ethylene mixture gas to be separated is flowed, ethane having a higher adsorption power to the filled adsorbent occupies the adsorption site and desorbs relatively weakly adsorbed ethylene. Therefore, these desorbed ethylene are combined with ethylene in the mixed gas. Since it is discharged, the ethane content in the exhaust gas decreases and the ethylene content increases, so that it was possible to recover high purity ethylene.

Claims (7)

A composition for separating ethane and ethylene, including pores having an average diameter of 2 nm or less, and including a carbon structure having a single-layer graphene pore wall as an active ingredient.
The method of claim 1,
The carbon structure is performed at 400 to 650° C. by supplying a mixed gas containing an unsaturated aliphatic hydrocarbon, a carrier gas and water vapor to a zeolite containing an active metal, which is an empty d-orbitial metal. The composition for separating ethane and ethylene is formed along the pore walls of the template by chemical vapor deposition.
The method of claim 2,
The zeolite is LTL, VFI, MAZ, MEI, FAU, EMT, OFF, BEA, MOR, MFI, MPS, MEL, MTW, EUO, MTT, HEU, FER, TON, CHA, ERI, KFI, LEV, LTA, or these A composition for separating ethane and ethylene, which is of a mixed structural type.
As an adsorbent, ethane/ethylene mixing comprising the step of contacting a mixed gas containing ethane and ethylene to a reactor having a carbon structure comprising pores having an average diameter of less than 2 nm and having a single-layer graphene pore wall Gas adsorption separation method.
The method of claim 4,
Adsorption separation method to adsorb ethane predominantly compared to ethylene containing four CH bonds through the attraction of CH ... π between the π-bonds of graphene and the 6 CH bonds of ethane constituting the carbon structure .
The method of claim 4,
The carbon structure is formed by supplying a mixed gas containing an unsaturated aliphatic hydrocarbon, a carrier gas, and water vapor to a zeolite ion-exchanged with a metal in which d-orbital electrons are vacant, and the pore wall of the template is carried out at 400 to 650°C. It is prepared by a method comprising a first step of forming according to and a second step of selectively removing zeolite by wet etching using an aqueous acid solution.
The adsorbent layer includes pores with an average diameter of less than 2 nm and has a carbon structure with a single-layer graphene pore wall, and has a gas inlet on one side and a gas outlet on the other side. A mixed gas containing ethane and ethylene with a pressure of more than 0 bar and 20 bar or less containing 50 mol% of ethane is injected into the reactor discharged through the gas outlet to adsorb ethane, while the ethane content is reduced from the gas outlet. A first step of collecting ethylene gas reduced to less than 1 mol%;
When the ethane content in the gas discharged from the gas outlet is 1 mol% or more, ethylene gas with a purity of 99 mol% or more is injected into the reactor in which the ethane is adsorbed at a pressure less than the adsorption pressure to desorb the adsorbed ethane while adsorbing ethylene. A second step of saturating the layer; And
Injecting a mixed gas containing ethane and ethylene having a pressure of more than 0 bar and not more than 20 bar to a reactor in which the adsorbent layer is saturated with ethylene to absorb ethane, while collecting ethylene gas having an ethane content of less than 1 mol% from the gas outlet. A method for producing ethylene gas having a purity of 99 mol% or more, including a third step.

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