JP2018111057A - Wet oxidation method and device for water containing organic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet oxidation method and device for water containing an organic material conducting wet oxidative decomposition of an organic compound by making the waste water containing the organic compound come in contact with a catalyst carrying a platinum group metal, which can obtain stable oxidative decomposition effect without being influenced by shape of a reactor and a direction of fluid supply.SOLUTION: Heated air is made to flow through a rector 8. Then, the water containing an organic material in a tank 20 heated by a heat exchanger 6 and a heater 7 is made to flow through the reactor 8, to come in contact with a catalyst carrying a noble metal, and wet oxidation of the organic material is carried out. Water flowing out the reactor 8 is introduced, via a valve 24 and a back pressure valve 25, into a heat source side of the heat exchanger 6; is heat-exchanged with the water containing the organic material from the tank 20; and is taken out as treated water. Subsequently, the air passing step and the water passing step are repeated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and apparatus for wet oxidation treatment of organic substance-containing water, and more particularly to a method and apparatus for decomposing organic substances in water to be treated with a metal catalyst.

As a method for wet oxidation treatment of wastewater containing an organic compound using a metal catalyst, Patent Document 1 discloses a reaction temperature of 200 to 270 ° C. and a reaction pressure when drainage is passed through a catalyst supporting a platinum group metal. The treatment with 30 to 70 kg / cm ² G is described. In Patent Literature 1, oxygen gas, oxygen-enriched air, or normal air is used as an oxygen source. In the example of Patent Document 1, batch processing using an autoclave is described. In this embodiment, wastewater and air are simultaneously introduced into an autoclave, and the inside of the autoclave is stirred to perform wet decomposition of the organic compound.

  In Patent Document 2, waste water and an oxygen-containing gas are circulated in a downward flow in a reaction column filled with a noble metal-supported catalyst at a temperature of 100 to 270 ° C. and a reaction pressure at which a liquid phase is maintained, and an organic compound is wet-oxidized. A method of processing is described. The method of Patent Document 2 is a continuous type, and waste water and oxygen-containing gas are continuously supplied simultaneously.

  Patent Document 3 describes a wet oxidation process in which wastewater and oxygen-containing gas are passed through a reaction tank filled with a noble metal-supported activated carbon catalyst layer in a downward flow at a temperature of 100 ° C. or lower.

  In Patent Document 4, as a wet catalytic oxidation tower for the purpose of avoiding an increase in pressure loss and a clogging phenomenon, waste water and an oxygen-containing gas are simultaneously caused to flow upward in a reaction tower containing an oxidation catalyst having a honeycomb structure. A wet catalytic oxidation tower is described.

Japanese Patent Laid-Open No. 7-232182 Japanese Patent Application Laid-Open No. 10-113680 JP 11-179378 A JP 2003-340471 A

  In the wet oxidation treatment of organic substance-containing water, oxygen molecules are adsorbed to the noble metal of the noble metal-supported catalyst, and when the organic compound in the wastewater comes into contact therewith, the oxidation reaction of the organic compound proceeds. Therefore, in the wet oxidation method of Patent Document 1 in which batch processing is performed, it is necessary to stir the reactor filled with the noble metal-supported catalyst so that the waste water and gas are brought into uniform contact with the noble metal-supported catalyst. It is necessary to provide a stirring mechanism in the vessel. Moreover, in patent documents 2-4, it was necessary to distribute | circulate a gas-liquid two-phase flow by a downward flow or an upward flow with respect to a reaction tower.

  The present invention is a method and apparatus for wet oxidative decomposition treatment of an organic compound by contacting waste water containing the organic compound with a noble metal-supported catalyst, and stable oxidative decomposition without being affected by the shape of the reactor and the direction of fluid supply It is an object of the present invention to provide a method and apparatus for wet oxidation treatment of organic substance-containing water capable of obtaining the effect.

  The method for wet oxidation treatment of organic substance-containing water according to the present invention is a method for wet oxidation treatment of organic substance-containing water using a reactor filled with a noble metal-supported catalyst, and a venting step of ventilating an oxygen-containing gas through the reactor; Then, it has a water flow process which allows only water containing organic substance to flow through the reactor.

  The wet oxidation treatment apparatus for organic matter-containing water according to the present invention is a wet oxidation treatment apparatus for organic matter-containing water having a reactor filled with a wet oxidation catalyst, and supplies the reactor with an oxygen-containing gas and organic matter-containing water by switching. It is characterized by having a supply means.

  In one embodiment of the present invention, the reactor temperature is set to 80 ° C. or higher, and the oxygen-containing gas is supplied to the reactor.

In one embodiment of the present invention, the oxygen-containing gas is air, and is passed through the catalyst layer in the reactor at SV1 to 200 hr ⁻¹ for ¹ to 10 hr.

  In one embodiment of the present invention, waste gas from the reactor is passed through a heat exchanger, the oxygen-containing gas is heated, and the waste gas flowing out of the heat exchanger is blown into a tank containing organic matter-containing water.

  In the present invention, before supplying the organic substance-containing water into the reactor, an oxygen-containing gas is supplied into the reactor to sufficiently adsorb oxygen molecules on the noble metal of the noble metal-supported catalyst. Thereafter, the supply of the oxygen-containing gas is stopped, the organic substance-containing water is supplied to the reactor, and the organic substance is oxidized and decomposed by reacting the oxygen adsorbed on the noble metal with the organic substance. In the method and apparatus of the present invention, it is not necessary to provide a stirring means in the reactor, or to consider the shape of the reactor or the flow direction in which gas-liquid separation does not occur, and the size and arrangement of the catalytic reactor can be set under desired conditions. It becomes possible to install.

It is a systematic diagram which shows embodiment of the processing method of the organic substance containing water of this invention. It is a systematic diagram which shows embodiment of the processing method of the organic substance containing water of this invention. 3 is a graph showing the results of Example 1. 10 is a graph showing the results of Example 2. 6 is a graph showing the results of Comparative Example 1.

  Hereinafter, embodiments of the method for treating organic substance-containing water of the present invention will be described in detail.

  In the method and apparatus for wet oxidation treatment of organic substance-containing water according to the present invention, the oxygen-containing gas is supplied while drying the noble metal-supported catalyst accommodated in the reactor to adsorb oxygen to the noble metal of the noble metal-supported catalyst, and then the reactor Water containing organic matter is passed through to carry out wet oxidation treatment of the organic matter.

  Examples of the noble metal used for the noble metal-supported catalyst include a platinum group (ruthenium, rhodium, palladium, osmium, iridium and platinum). These platinum groups can be used alone, in combinations of two or more, can be used as alloys of two or more, or can be a naturally produced mixture of refined products. Can also be used without separating them into single bodies. Among these, platinum, palladium, a platinum / palladium alloy alone or a mixture of two or more of them is particularly suitable because of its strong catalytic activity.

  The platinum group metal may be platinum group metal fine particles, or may be a metal supported catalyst in which platinum group metal nanocolloid particles are supported on the surface of the support.

  There is no restriction | limiting in particular in the method of manufacturing a platinum group metal nano colloid particle, For example, a metal salt reduction reaction method, a combustion method, etc. can be mentioned. Among these, the metal salt reduction reaction method can be suitably used because it is easy to produce and stable metal nanocolloid particles can be obtained. As the metal salt reduction reaction method, for example, 0.1 to 0.4 mmol / L aqueous solution of chloride such as platinum, nitrate, sulfate, metal complex, etc., alcohol, citric acid or a salt thereof, formic acid, acetone, Metal nanocolloid particles can be produced by adding 4 to 20 equivalents of a reducing agent such as acetaldehyde and boiling for 1 to 3 hours. Further, for example, by dissolving 1-2 mmol / L of hexachloroplatinic acid, potassium hexachloroplatinate, etc. in an aqueous polyvinylpyrrolidone solution, adding a reducing agent such as ethanol, and heating and refluxing in a nitrogen atmosphere for 2 to 3 hours, Nanocolloid particles can be produced.

  The average particle size of the platinum group metal nanocolloid particles is preferably 1 to 50 nm, more preferably 1.2 to 20 nm, and still more preferably 1.4 to 5 nm. If the average particle size of the metal nanocolloid particles is less than 1 nm, the catalytic activity for TOC decomposition and removal may be reduced. When the average particle diameter of the metal nanocolloid particles exceeds 50 nm, the specific surface area of the nanocolloid particles becomes small, and the catalytic activity for TOC decomposition and removal may be reduced.

  There is no restriction | limiting in particular in the support | carrier which carry | supports the platinum group metal nano colloid particle, For example, a magnesia, a titania, an alumina, a silica-alumina, a zirconia, activated carbon, a zeolite, a diatomaceous earth, an ion exchange resin etc. can be mentioned. The average particle size (measured by JIS mesh) of the carrier is preferably about 20 to 2000 μm, particularly about 50 to 1000 μm.

  The amount of noble metal supported on the carrier is preferably about 0.1 to 30 wt%, particularly about 1 to 10 wt%.

  As the oxygen-containing gas supplied into the reactor, pure oxygen is most preferably used, but air, oxygen-enriched air, and the like can also be used.

  When supplying the oxygen-containing gas to the reactor, the temperature of the reactor is set to 80 ° C. or higher, the oxygen-containing gas is supplied to the reactor, and the noble metal-supported catalyst in the reactor is dried.

The supply SV (standard state; hereinafter the same) of the oxygen-containing gas to the packed bed of the noble metal-supported catalyst packed in the reactor is preferably about ¹ to 200 hr ^−1, particularly about 6 to 120 hr ⁻¹ . The supply time of the oxygen-containing gas is preferably about 1 to 10 hours, particularly about 2 to 5 hours.

  After circulating the oxygen-containing gas through the reactor, the organic substance-containing water is passed through the reactor.

  The present invention is suitable for treating wastewater containing organic matter such as industrial wastewater. The present invention is suitable for application when the organic matter concentration of this raw water is 1 to 10,000 mg / L, particularly about 10 to 500 mg / L as TOC (total organic carbon). However, the present invention can be applied to treatment of various other organic substance-containing water.

In the present invention, the reactor itself is heated to 80 ° C. or higher, and the temperature of the liquid to be treated is heated to 60 to 200 ° C., particularly 80 to 180 ° C., thereby increasing the wet oxidation rate of the organic matter. be able to. The water passing SV to the noble metal-supported catalyst packed bed of organic substance-containing water is preferably about 0.1 to 10 hr ^−1, particularly about 0.5 to 5 hr ⁻¹ .

  The passage time of the organic substance-containing water is proportional to the catalyst filling amount, and is preferably about 1 to 24 hours per liter of the catalyst. When passing water containing organic matter, a back pressure valve is provided in the outlet line, and the inside of the reactor may be pressurized to a pressure at which the water to be treated does not boil in the reactor.

  FIG. 1 shows the configuration of an organic substance-containing water treatment apparatus according to an embodiment. In this embodiment, air and organic substance-containing water are alternately supplied to one reactor.

  FIG. 1A shows a state where air is supplied to the reactor. The air is heated by the heat exchanger 6 and the heater 7 through the blower 1, the flow controller 2, the valve 3, the pipes 4 and 5, and then circulated to the reactor 8. A heater H is provided in the reactor 8. A packed bed of noble metal supported catalyst is provided in the reactor 8. The air that passed through the reactor 8 (waste air) is circulated to the heat source side of the heat exchanger 6 through the pipes 9 and 10, the valve 11, and the pipe 12, and after exchanging heat with the air from the blower 1, 14, the organic substance-containing water tank 20 is blown through the valve 15 and the pipe 16. By blowing waste air into the tank 20, it is possible to heat the organic substance-containing water in the tank 20 and to collect dust and the like in the waste air.

  In FIG. 1A, the valves 3, 10, and 15 are opened, and the valves 22, 24, and 28 are closed. Further, the pump 21 is stopped.

  FIG. 1B shows a state in which the organic substance-containing water is subsequently passed through the reactor 8.

  In FIG. 1B, the organic substance-containing water in the tank 20 is heated by the heat exchanger 6 and the heater 7 through the pump 21, the valve 22 and the pipe 5, and then passed through the reactor 8, and the noble metal supported catalyst. And wet oxidation treatment of organic matter is performed. The water flowing out from the reactor 8 is introduced to the heat source side of the heat exchanger 6 through the pipe 9, the pipe 23 branched from the pipe 9, the valve 24, the back pressure valve 25, the pipe 26 and the pipe 12, and from the tank 20. After exchanging heat with organic substance-containing water, it is taken out as treated water through the pipe 13, the pipe 27 branched from the pipe 13, and the valve 28.

  In FIG. 1B, the valves 22, 24, and 28 are opened, and the valves 3, 11, and 15 are closed.

  As shown in FIG. 1 (b), after processing the organic substance-containing water, the process returns to the process of FIG. 1 (a), and thereafter, the same process is repeated to treat the organic substance-containing water.

  In FIG. 1, air and organic substance-containing water are alternately supplied to one reactor 8, but in the present invention, two or more reactors are installed in parallel, and oxygen-containing gas is vented to some reactors. Meanwhile, water containing organic matter may be passed through the other reactor. An example is shown in FIG.

  In the embodiment shown in FIG. 2, two reactors 71 and 72 are installed in parallel, and oxygen-containing gas is vented to the other reactor while the organic substance-containing water is passed through the one reactor. ing.

  FIG. 2 shows a state in which organic substance-containing water is passed through the first reactor 71 and air is passed as oxygen-containing gas through the second reactor 72.

  That is, the organic substance-containing water in the tank 30 is supplied to the first reactor 71 through the pump 31, the heat exchanger 32, the water heater 33, the pipe 34, and the valve 35, and the wet oxidation process of the organic substance is performed. Outflow water from the first reactor 71 is passed through the valve 36, the pipe 37, the back pressure valve 38, and the pipe 39 to the heat source side of the heat exchanger 32, and then taken out as treated water through the pipe 40.

  The air is heated by the heat exchanger 52 and the air heater 53 from the blower 51 and then vented to the second reactor 72 through the pipes 54 and 55, the valve 56 and the pipe 57. Waste air flowing out from the second reactor 72 is vented to the heat source side of the heat exchanger 52 through the valve 58 and the pipes 59 and 60, and then blown into the tank 30 through the pipe 61. In this state, the valves 35, 36, 56, and 58 are opened, and the valves 42, 44, 63, and 65 are closed.

  When air is passed through the first reactor 71 and organic substance-containing water is passed through the second reactor 72, the valves 35, 36, 56, 58 are closed and the valves 42, 44, 63, 65 are opened. To do. Thereby, the organic substance-containing water in the tank 30 is supplied from the pump 31, the heat exchanger 32, the water heater 33, the pipe 34, the pipe 41 branched from the pipe 34, the valve 42, the pipe 43, the second reactor 72, the valve 44, The pipes 45 and 37, the back pressure valve 38, the pipe 39, the heat exchanger 32, and the pipe 40 flow in this order and are taken out as treated water.

  Air is blower 51, heat exchanger 52, air heater 53, pipe 54, pipe 62 branched from pipe 54, valve 63, pipe 64, first reactor 71, valve 65, pipes 66, 60, heat exchanger 52, pipe. It flows in the order of 61 and is blown into the organic substance-containing water in the tank 30.

  Thus, by supplying organic substance-containing water and air alternately to the first reactor 71 and supplying air and organic substance-containing water alternately to the second reactor 72, the entire apparatus has organic substance-containing water. Can be processed continuously.

[Example 1]
Using the wet oxidation apparatus shown in FIG. 1, water containing organic matter containing 100 mg / L of IPA as TOC was treated. In the reactor 8, a PFA cylindrical container having an inner diameter of 22 mm and a length of 630 mm is horizontally installed, and 240 mL of a catalyst in which 10 wt% of Pt is supported on an alumina carrier having an average particle diameter of 1000 μm is packed. An electric heater was wound around the reactor 8, and the entire reactor 8 was heated to 120 ° C. As shown in FIG. 1A, air was adjusted to 100 mL / min (SV = 25 hr ⁻¹ ) by the mass flow controller 2 and supplied to the reactor 8 while heating to 120 ° C. with the heater 7 for 3 hours.

Thereafter, the air supply was stopped, and the organic substance-containing water was heated to 120 ° C. with the heater 7 and passed at 3 mL / min as shown in FIG. At this time, the cylinder speed (SV) is 0.75 hr ⁻¹ . The temperature of the reactor 8 was 120 ° C., and the pressure in the reactor 8 was adjusted to 0.2 MPa with the back pressure valve 25.

  The treated water was sampled every hour for up to 10 hours, and the change in TOC concentration over time was measured. The result is shown in FIG. As shown in FIG. 3, the TOC concentration was found to be a low value of about 2 mg / L or less until about 7 hours passed from the start of water flow.

[Example 2]
The conditions are the same as in Example 1 except that the air supply time is 5 hours and the organic material-containing water flow time is 5 hours. Air aeration (5 hr) → organic substance-containing water flow (5 hr) → air aeration (5 hr) → The air supply and the organic substance-containing water supply were repeated twice as the organic substance-containing water flow (5 hr). The results of sampling the treated water every hour and measuring the TOC change over time are shown in FIG. As shown in FIG. 4, the TOC concentration of treated water was stable at 2 mg / L or less, and it was confirmed that stable treatment was possible.

[Comparative Example 1]
Using the same apparatus as in Example 1, a process for simultaneously supplying air and wastewater was performed. Water containing organic matter having the same TOC concentration as in Example 1 was supplied at 3 mL / min, and air was supplied at 6 mL / min. The air supply amount at this time corresponds to about twice the theoretical oxygen amount necessary for completely decomposing TOC into carbon dioxide gas. The reactor temperature and pressure were the same as in Example 1.

  The treated water was sampled every hour for up to 10 hours, and the change in TOC concentration over time was measured. The result is shown in FIG. As shown in FIG. 5, it was recognized that the TOC concentration increased with time and the treatment effect decreased. Further, when observing the catalyst reactor made of PFA, the supplied air is accumulated in the upper part of the reactor and the gas-liquid is separated while passing through the reactor, and the oxygen in the supplied air is not sufficiently in contact with the catalyst. It was recognized that the treatment effect was insufficient.

1,51 Blower 6,32,52 Heat exchanger 8 Reactor 25,38 Back pressure valve 20,30 Organic substance-containing water tank

Claims (6)

In the method of wet oxidation treatment of organic substance-containing water using a reactor filled with a noble metal supported catalyst,
A venting step of venting only oxygen-containing gas through the reactor;
Then, the wet oxidation method of the organic substance containing water characterized by having a water flow process of passing an organic substance containing water through this reactor.   2. The wet oxidation method for organic substance-containing water according to claim 1, wherein in the aeration step, the oxygen-containing gas is supplied by heating the reactor temperature to 80 to 180 ° C. 3. The wet oxidation method for organic substance-containing water according to claim 2, wherein the oxygen-containing gas is air and aeration is performed for ¹ to 10 hours at SV1 to 200 hr- ¹ with respect to the catalyst layer in the reactor. In a wet oxidation apparatus for water containing organic matter having a reactor filled with a wet oxidation catalyst,
An apparatus for wet oxidation of organic substance-containing water, characterized by comprising supply means for switching and supplying oxygen-containing gas and organic substance-containing water to the reactor.   5. The wet oxidation apparatus for organic substance-containing water according to claim 4, further comprising heating means for oxygen-containing gas and organic substance-containing water. In claim 5, as a heating means of the oxygen-containing gas, it comprises a heat exchanger through which waste gas flowing out of the reactor is vented to the heat source side,
An apparatus for wet oxidation of organic substance-containing water, wherein the waste gas flowing out of the heat exchanger is blown into a tank of organic substance-containing water.

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