JP5578608B2 - Carbon monoxide gas purification method - Google Patents

Description

  The present invention relates to a method for purifying carbon monoxide contained in a raw material gas by a pressure swing adsorption method (PSA method).

  For example, a reformed gas obtained by reforming a hydrocarbon gas such as natural gas or methanol, etc., contains components such as carbon monoxide, carbon dioxide, hydrogen, etc., as a raw material gas for obtaining carbon monoxide by purification Used. Carbon monoxide separated and purified from the components contained in such a raw material gas using an adsorbent can be used, for example, as a resin raw material such as polycarbonate, polyurethane, or polyketone, or as a chemical raw material such as acetic acid or aldehydes.

  As an adsorbent used for adsorption of carbon monoxide, activated carbon supporting cuprous chloride is used. As a method for producing such an adsorbent, the activated carbon is immersed in a hydrochloric acid solution of cuprous chloride to support the cuprous chloride on the activated carbon, and the activated carbon supporting the cuprous chloride is dried to adsorb the adsorbent. Is known (Patent Document 1). In addition, when activated carbon carrying a copper salt such as cuprous chloride or cupric chloride is used as an adsorbent for carbon monoxide, it is heated to a temperature exceeding 250 ° C. in order to recover the adsorption capacity of the adsorbent. Thus, a method for activation treatment is known (Patent Document 2). As a method for purifying carbon monoxide contained in a raw material gas, it is known to employ a pressure swing adsorption method using activated alumina supporting cuprous chloride, cupric chloride or the like as an adsorbent (Patent Document). 3). Moreover, when purifying carbon monoxide by adopting a pressure swing adsorption method using activated carbon supporting copper halide as an adsorbent, the adsorption bed temperature is controlled in the range of 40 to 60 ° C. A method for improving the recovery rate is known (Patent Document 4).

Japanese Patent Laid-Open No. 62-114646 Japanese Patent Laid-Open No. 62-176540 Japanese Patent Laid-Open No. 5-23523 JP-A-11-104431

  In the method described in Patent Document 1, since the adsorbent is obtained using cuprous chloride which is easily oxidized, it is necessary to consider the handling. In the method described in Patent Document 2, the adsorbent is heated at 250 ° C. or higher in order to activate the adsorbent. In the method described in Patent Document 3, since the adsorption ability of carbon monoxide is low, the purification equipment must be enlarged in order to obtain a desired purification capacity, and this is not an industrially advantageous method. In the method described in Patent Document 4, the highest purity of carbon monoxide after purification is 99.5%, and carbon monoxide having sufficiently high purity cannot be obtained. An object of this invention is to provide the purification method of carbon monoxide which can solve the subject of such a prior art.

The present invention is a carbon monoxide purification method for purifying carbon monoxide contained in a raw material gas by a pressure swing adsorption method using an adsorbent, in which cupric chloride is dissolved in a hydrochloric acid solution and activated carbon is immersed, Thereafter, by adding metallic copper to the solution, cupric chloride and metallic copper are reacted to produce cuprous chloride, and the produced cuprous chloride is supported on activated carbon, and the adsorption is performed. as agents, characterized by using the activated carbon carrying a cuprous salt of.
According to the present invention, activated carbon supporting cuprous chloride can be obtained as an adsorbent without using cuprous chloride which is easily oxidized as a raw material for the adsorbent of carbon monoxide. Thereby, the handling at the time of manufacturing an adsorbent becomes easy. Moreover, the adsorption ability of carbon monoxide can be improved by immersing activated carbon in the hydrochloric acid solution of cuprous chloride compared with the case where cuprous chloride is supported on activated carbon.

In the present invention, it is to wash the active carbon carrying the cuprous salt of the time of separation from the solution, preferably in removing hydrochloric acid and pulverulent activated carbon.

The adsorbent obtained according to the present invention is preferably subjected to an activation treatment at a temperature between 15 ° C. and 180 ° C. The activation treatment at 180 ° C. below the temperature can be improved adsorption performance of carbon monoxide, the activation treatment temperature in order to sufficiently improve the adsorption performance is preferably more than 1 5 0 ° C.. By setting the temperature for the activation treatment to 180 ° C. or lower, corrosion of the equipment can be suppressed and energy consumption can be reduced. The activation treatment is preferably performed under an inert gas stream.

  ADVANTAGE OF THE INVENTION According to this invention, the purification method of carbon monoxide which can refine | purify high purity carbon monoxide at low cost can be provided, without enlarging refinement | purification equipment.

Configuration explanatory diagram of a pressure swing adsorption device for purifying carbon monoxide according to an embodiment of the present invention

  In the method for purifying carbon monoxide according to the present invention, the type of raw material gas containing carbon monoxide is not particularly limited. For example, a reformed gas obtained by reforming a hydrocarbon gas such as natural gas or methanol is used as a raw material. Gas.

  The adsorbent for adsorbing carbon monoxide contained in the raw material gas may be activated carbon supporting cuprous chloride obtained by reacting cupric chloride and metallic copper in the presence of hydrochloric acid. . For example, by dissolving cupric chloride in a hydrochloric acid solution and immersing activated carbon, and then adding metallic copper to the solution and stirring, the cupric chloride reacts with metallic copper to produce first chloride. Copper is produced and the produced cuprous chloride is supported on activated carbon. The obtained activated carbon carrying cuprous chloride is separated from the remaining solution after the reaction by filtration, washed to remove hydrochloric acid and pulverized activated carbon, and then dried to adsorb. The agent is manufactured.

  The amount of cupric chloride used in the production of the adsorbent is preferably 10 to 80 parts by weight, preferably 40 to 70 parts by weight with respect to 100 parts by weight of activated carbon, from the viewpoint of improving the adsorption performance of the adsorbent obtained. It is more preferable that Cupric chloride may be an anhydride or a hydrate.

  The amount of metallic copper used in the production of the adsorbent is preferably 0.8 to 1.2 mol per mol of cupric chloride from the viewpoint of improving the adsorption performance of the adsorbent obtained. It is more preferably 9 to 1.1 mol. The form of the metallic copper is not particularly limited, but is preferably in the form of powder from the viewpoint of improving the reaction rate.

  The amount of hydrochloric acid used in the production of the adsorbent is preferably from 0.1 to 100 mol, more preferably from 0.1 to 20 mol, based on 1 mol of metallic copper, from the viewpoint of improving reaction efficiency. .

  The type of activated carbon supporting cuprous chloride is not particularly limited, but considering that it is used in the PSA method, for example, 8-14 mesh crushed charcoal (G2c manufactured by Nippon Environment Co., Ltd.), 4 mm in diameter Pellet-shaped coal (Mitsubishi Chemical Calgon Co., Ltd. ZGN4) etc. can be mentioned.

  As a solvent used when reacting cupric chloride and metallic copper in the presence of hydrochloric acid and activated carbon, an aqueous hydrochloric acid solution may be used as a solvent. For example, methanol, ethanol, n-propanol, iso-propanol Alcohols such as dimethyl ether, thiethyl ether, di-n-propyl ether, di-iso-propyl ether, ethers such as oxane, water and the like may be used in combination.

  The atmosphere when the cupric chloride and metallic copper are reacted in the presence of hydrochloric acid and activated carbon is preferably an inert gas or a reducing gas. Examples of the inert gas include nitrogen, argon, and helium, and examples of the reducing gas include hydrogen, carbon monoxide, hydrogen sulfide, and formaldehyde. Among these, nitrogen is preferable.

  The reaction temperature when reacting cupric chloride and metallic copper in the presence of hydrochloric acid and activated carbon is not particularly limited. For example, the reaction temperature may be 25 ° C. to 50 ° C., and the reaction time is not particularly limited. Time to about 5 hours.

  For example, centrifugation, pressure filtration, suction filtration, or the like can be adopted as the filtration method. The filtration temperature is preferably 20-30 ° C. If the filtration temperature is less than 20 ° C, the produced cuprous chloride may be precipitated, and if it exceeds 30 ° C, the produced cuprous chloride may be dissolved in the filtrate and the adsorption performance may be reduced.

  The method for washing when separating the activated carbon supporting cuprous chloride from the solution is not particularly limited. For example, before the filtration process, the liquid layer in the reaction vessel is decanted to remove fine particles of activated carbon floating in the liquid. Fine powder may be reduced. After the decantation, pure water or degassed water may be added to the reaction vessel and the decantation may be repeated to perform washing again. This can reduce activated carbon fine powder and reduce residual hydrochloric acid. The effect of preventing the corrosion of equipment can be achieved. The amount of pure water or degassed water used for cleaning by repeated decantation is preferably 100 to 1000 parts by weight with respect to 100 parts by weight of activated carbon. For example, when performing filtration using a pressure filter using a mesh-like filter plate, the activated carbon supporting cuprous chloride is washed with pure water or deaerated water instead of decantation. The fine powder of activated carbon and residual hydrochloric acid may be reduced.

  As a dryer used for drying activated carbon carrying cuprous chloride, for example, a conical dryer or a shelf dryer can be used. The drying temperature is preferably 80 to 150 ° C, more preferably 90 to 120 ° C. The drying pressure can be dried at normal pressure, but it is more preferable to dry at 50 mmHg or less under reduced pressure.

  Carbon monoxide contained in the raw material gas is purified by the pressure swing adsorption method using the adsorbent obtained as described above. As a pressure swing adsorption apparatus including an adsorption tower for filling the adsorbent, a known apparatus as shown in FIG. 1 can be used, and the pressure swing adsorption method can be performed at room temperature. The number of adsorption towers of the pressure swing adsorption apparatus is not particularly limited, and is, for example, 2 to 4 towers. It is preferable to increase the activity of the adsorbent by performing an activation treatment at a temperature of 120 to 180 ° C. when the adsorbent is packed in the adsorption tower or when the performance of the adsorbent is lowered due to subsequent use. The time for the activation treatment is not particularly limited, and is preferably 2 to 15 hours, for example, and is preferably performed under an inert gas stream.

  The pressure swing adsorption apparatus 1 shown in FIG. 1 is a three-column type, has first to third adsorption towers 2, a vacuum pump 3, and a product gas holder 4, and each adsorption tower 2 is filled with an adsorbent. The inlet 2a of each adsorption tower 2 is connected to a raw material gas supply source 6 such as a methanol reformer via a switching valve 5a, and connected to a product gas holder 4 via a switching valve 5b and a piping switching valve 7. It is connected to the suction port of the vacuum pump 3 through the valve 5c. The discharge port of the vacuum pump 3 is connected to the product gas holder 4. The outlet 2b of each adsorption tower 2 is connected to the outflow pipe 8 through the switching valve 5d, and is connected to the communication pipe 9 through the switching valve 5e.

  Each switching valve 5a-5e is comprised by the automatic valve, and is operated according to the program memorize | stored in the control apparatus (illustration omitted). By operating each switching valve 5a to 5e, the six adsorption steps of the first adsorption process, the second adsorption process, the cleaning process, the first desorption process, the second desorption process, and the pressure raising process are performed in this order in each adsorption tower 2. Done. Further, as shown in Table 1 below, the six steps are executed at different times in the three adsorption towers 2, thereby continuously purifying carbon monoxide.

  The first adsorption step is a step of adsorbing carbon monoxide contained in the raw material gas to the adsorbent in the adsorption tower 2. When the first adsorption tower 2 is in the first adsorption step, the switching gas 5a, 5d of the first adsorption tower 2 is opened and 5b, 5c, 5e are closed, so that the source gas is introduced into the first adsorption tower 2. Then, carbon monoxide contained in the raw material gas is adsorbed by the adsorbent, and the remaining gas is discarded out of the system via the outflow pipe 8 as impurities.

  The second adsorption step is a step for performing a pressure increasing step in another adsorption tower 2 after the carbon monoxide concentration of the waste gas gradually increases with time in the first adsorption step. When the first adsorption tower 2 is in the second adsorption process, carbon monoxide is adsorbed in the first adsorption tower 2 in the same manner as in the first adsorption process, and the waste gas is used for the pressure raising process in the second adsorption tower 2. In order to use it as a pressure increasing gas, the switching valve 5d is closed and 5e is opened in the first adsorption tower 2, and the switching valves 5a to 5d are closed and the switching valve 5e is opened in the second adsorption tower 2.

  The cleaning step is a step for discharging impurities in the internal space of the adsorption tower 2 after the adsorption in the second adsorption step. When the first adsorption tower 2 is in the cleaning process, the switching valves 5a, 5c, and 5e of the first adsorption tower 2 are closed, the switching valves 5b and 5d are opened, and the pipe switching valve 7 is opened. Thereby, high-purity carbon monoxide is introduced into the first adsorption tower 2 as a cleaning gas from the third adsorption tower 2 in the second desorption step, and the gas containing impurities inside the first adsorption tower 2 is high. The carbon monoxide gas is replaced with pure carbon monoxide gas, and the substituted gas is discarded outside the system via the outflow pipe 8. At this time, a part of the high-purity carbon monoxide gas in the product gas holder 4 may be introduced into the first adsorption tower 2 as a cleaning gas.

  The first desorption step is a step of desorbing carbon monoxide from the adsorbent of the adsorption tower 2 after the cleaning step. When the first adsorption tower 2 is in the first desorption step, the switching valves 5a, 5b, 5d, and 5e of the first adsorption tower 2 are closed, the switching valve 5c is opened, and the vacuum pump 3 The inside is depressurized. Thereby, carbon monoxide is desorbed from the adsorbent of the first adsorption tower 2, and the desorbed carbon monoxide is stored in the product gas holder 4. Carbon monoxide stored in the product gas holder 4 is taken out via the pipe 10.

  The second desorption process is a process for desorbing carbon monoxide from the adsorbent in the adsorption tower 2 following the first desorption process and performing a washing process in another adsorption tower 2. When the first adsorption tower 2 is in the second desorption process, the switching valves 5a, 5c, and 5e are closed, the switching valves 5b and 5d are opened, and the pipe switching valve 7 is opened in the second adsorption tower 2 that performs the cleaning process. Is opened. Thereby, high-purity carbon monoxide desorbed from the adsorbent of the first adsorption tower 2 is introduced into the second adsorption tower 2 as a cleaning gas. At this time, a part of the carbon monoxide stored in the product gas holder 4 may be introduced into the second adsorption tower 2 as a cleaning gas.

  The pressure increasing step is a step of increasing the pressure inside the adsorption tower 2 in a reduced pressure state after the second desorption step to a normal pressure state. When the first adsorption tower 2 is in the pressure increasing process, the switching valves 5a to 5d of the first adsorption tower 2 are closed, the switching valve 5e is opened, and the switching valves 5b to 5d of the third adsorption tower 2 are closed. The switching valves 5a and 5e are opened. Thereby, the waste gas discharged | emitted from the 3rd adsorption tower 2 in a 2nd adsorption process is introduce | transduced into the 1st adsorption tower 2, and the inside of the 1st adsorption tower 2 is pressurized. It should be noted that by opening the switching valve 5a of the adsorption tower 2 in the pressure increasing step, the pressure increasing step using the raw material gas together with the waste gas from another adsorption tower 2 or in place of the waste gas from the other adsorption tower 2 May be performed.

  According to the above embodiment, activated carbon supporting cuprous chloride can be obtained as the adsorbent without using cuprous chloride which is easily oxidized as a raw material for the carbon monoxide adsorbent. Thereby, the handling at the time of manufacturing an adsorbent becomes easy. Furthermore, by supporting the cuprous chloride on the activated carbon according to the above-described embodiment, the carbon monoxide is compared with the case of supporting the cuprous chloride on the activated carbon by immersing the activated carbon in a hydrochloric acid solution of cuprous chloride. Adsorption ability can be improved. When the crude carbon monoxide in the methanol cracked gas was purified by the pressure swing adsorption method using the pressure swing adsorption apparatus 1 equipped with the adsorption tower 2 filled with the adsorbent obtained by the above embodiment, it was 99.9 vol% or more. Purified carbon monoxide gas could be obtained. In addition, when the adsorbent is produced, the activated carbon supporting cuprous chloride is washed when it is separated from the solution, and the fine particles and hydrochloric acid content in the adsorbent are reduced, so that the switching valves 5a to 5e of the pressure swing adsorption device 1 are reduced. The amount of fine powder adhering to the surface was reduced, and it was necessary to remove the fine powder by an operation of about 30 hours before, but the fine powder removal work became unnecessary even after one month of continuous operation. Moreover, corrosion of an installation can be suppressed and the energy consumption can be reduced by setting the temperature for the activation treatment of the adsorbent to 180 ° C. or lower.

In a 5 L flask equipped with a stirrer, 852 g of cupric chloride hydrate (CuCl ₂ .2H ₂ O) was dissolved in 2 L of 35 wt% hydrochloric acid. Next, 1000 g of 8-14 mesh crushed charcoal (G2c manufactured by Nippon Enviro Co., Ltd.) was added to this solution, and the mixture was stirred for 1 hour, then mixed with 318 g of 280 mesh copper powder, and stirred for 3 hours. And mixed. Thus, cupric chloride was produced by reacting cupric chloride with metallic copper in the presence of hydrochloric acid, and the produced cuprous chloride was supported on activated carbon. After the addition of the copper powder, the flask was maintained in an oxygen-free state with a nitrogen atmosphere. When an inert gas typified by nitrogen gas is used as the nitrogen atmosphere, the oxygen content as an impurity in the inert gas is preferably as small as possible in order to prevent a decrease in the adsorption capacity of the adsorbent. The activated carbon supporting the cuprous chloride was separated from the remaining solution after the reaction by filtration at 25 ° C., and then washed with 1000 g of degassed water. After the washing, the activated carbon supporting cuprous chloride is dried at a temperature of 110 ° C. or higher under a reduced pressure maintaining a vacuum pressure of 6000 Pa (45 torr) or less, thereby removing excess water and hydrogen chloride. An adsorbent was obtained.
400 g of the adsorbent thus obtained was packed in each adsorption tower 2 of the three-column pressure swing adsorption apparatus 1 shown in the above embodiment. Each adsorption tower 2 has a cylindrical shape with a nominal diameter of 40A. After the filling, nitrogen gas was passed through each adsorption tower 2 and the adsorbent activation treatment was performed at 150 ° C. for 5 hours under this nitrogen gas flow.
Thereafter, carbon monoxide contained in the raw material gas was purified by a pressure swing adsorption method using the pressure swing adsorption apparatus 1. A reformed gas generated by a methanol reformer is used as a raw material gas, and the composition thereof is hydrogen (H ₂ ) 67.0 vol%, carbon monoxide (CO) 33.0 vol%, carbon dioxide (CO ₂ ) 0. 25 vol% and methane (CH ₄ ) 0.15 vol%. The operating conditions of the pressure swing adsorption apparatus 1 were such that the adsorption time in each adsorption tower 2 was 300 seconds, the pressure in the desorption process was 2266 Pa (17 torr), and the washing time was 60 seconds. As a result, a carbon monoxide gas having a high purity of 99.9 vol% or more could be obtained. Incidentally, when the operation state of the pressure swing adsorption device 1 becomes a steady state, the purity of the obtained carbon monoxide gas reaches 99.97 vol%, and its impurities are 120 volppm of hydrogen, 190 volppm of carbon dioxide, 1 volppm of methane, The recovery rate of carbon oxide was 96.8%.

Comparative example

719 g of cuprous chloride was dissolved in 2 L of 35 wt% hydrochloric acid at 100 ° C., 1000 g of 8-14 mesh crushed charcoal (G2c manufactured by Nippon Enviro Co., Ltd.) was added to this solution, and the mixture was stirred at 100 ° C. for 2 hours and mixed. I let you. The crushed charcoal was pretreated for 3 hours at a temperature of 100 ° C. to 150 ° C. and a reduced pressure of 667 Pa (5 torr) or less before being put into the solution. Thus, after supporting cuprous chloride on the activated carbon in the solution, the solution is filtered at 25 ° C. under a nitrogen gas stream to separate the activated carbon supporting cuprous chloride from the solution. By drying at a temperature of 120 ° C. under a reduced pressure of 667 Pa (5 torr), 1405 g of an adsorbent was obtained.
Carbon monoxide was purified by the pressure swing adsorption method using the pressure swing adsorption apparatus 1 in the same manner as in the Examples except that the adsorbent thus obtained was used. As a result, the purity of the carbon monoxide gas obtained was 99.2 vol% even after the operating state of the pressure swing adsorption device 1 became a steady state, and the recovery rate of carbon monoxide was 92.8%. .

  According to the above examples, the activated carbon supporting cuprous chloride can be obtained as the adsorbent without using cuprous chloride which is easily oxidized as a raw material of the adsorbent as in the comparative example. Handling during manufacturing has become easier. And according to the Example, it has confirmed that the refinement | purification ability of carbon monoxide could be improved rather than a comparative example. Since cupric chloride is easier to impregnate activated carbon by dissolving in a solvent than cuprous chloride, rather than directly supporting cuprous chloride on activated carbon, cupric chloride impregnated on activated carbon is metallic copper. It is considered that cuprous chloride can be effectively supported on the activated carbon by reacting with copper to make cuprous chloride.

  The present invention is not limited to the above embodiments and examples. For example, the configuration of the pressure swing adsorption device is not particularly limited as long as the pressure swing adsorption method can be performed.

  DESCRIPTION OF SYMBOLS 1 ... Pressure swing adsorption apparatus, 2 ... Adsorption tower, 3 ... Vacuum pump, 4 ... Product gas holder, 6 ... Raw material gas supply source

Claims (3)

In a carbon monoxide purification method for purifying carbon monoxide contained in a raw material gas by a pressure swing adsorption method using an adsorbent,
Dissolving cupric chloride in hydrochloric acid solution and immersing activated carbon, and then adding metallic copper to the solution to react cupric chloride and metallic copper to produce cuprous chloride, The produced cuprous chloride is supported on activated carbon,
As the adsorbent, the purification method of carbon monoxide, which comprises using the active carbon carrying the cuprous salt of. The method for purifying carbon monoxide according to claim 1 , wherein the activated carbon supporting cuprous chloride is washed when separated from the solution. Purification method of carbon monoxide according to claim 1 or 2 performs activation processing of the adsorbent at a temperature between 1 5 0 to 180 ° C..

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