JP2794427B2 - Oxidation combustion method using heat conductive catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is intended to efficiently treat a fluid to be treated such as an organic substance in a factory exhaust gas, carbon monoxide or methane other than the organic substance, or a combustible substance such as methane. The present invention relates to an oxidative combustion method using a highly heat-conductive catalyst that can cause an oxidative combustion reaction.

[Conventional technology]

Conventionally, as an oxidation combustion method using a thermally conductive catalyst,
For example, there is a method in which the surface of a heat conductive carrier is roughened, and then an oxidative combustion reaction is performed using a heat conductive catalyst in which a metal having catalytic activity is supported. The catalyst reactant is roughened by performing a general roughening process on the surface of the heat conductive carrier.

As the catalyst reactant, for example, JP-A-47-3378
Japanese Unexamined Patent Application Publication No. 5 or JP-A-62-237947 is known.

These catalytic reactants are formed by forming at least the inner peripheral surface of the cylindrical heat conductive carrier, which serves as a flow path of the fluid to be treated, as a thermally conductive catalyst, so that the catalyst can only flow through the fluid in the cylinder. Some of them promote the oxidative combustion reaction of the fluid to be treated by the action to improve the reaction efficiency.

[Problems to be solved by the invention]

By the way, in the conventional oxidative combustion method using a thermally conductive catalyst, since the surface of the thermally conductive carrier is merely roughened by general roughening, a metal having catalytic activity is removed. The surface area that can be supported is not so large, and thus the catalytic reaction when oxidizing and burning reaction is performed using this catalytic reactant is not so good.

In addition, even when the tubular heat conductive carrier is used as a catalyst reactant, the inner peripheral surface of the cylinder on which a metal having catalytic activity is supported is roughened by general roughening as described above. Therefore, the catalytic reaction when the oxidative combustion reaction is similarly performed is not good.

The present invention has been made on the background of such a conventional technique, and an object of the present invention is to provide an oxidative combustion method using a thermally conductive catalyst that can further improve the reaction efficiency of a fluid to be treated.

[Means for solving the problem]

The present invention provides a method for roughening the surface of a heat conductive carrier,
After a heat treatment using hot water or steam at a temperature of 50 to 350 ° C. and a pH of 7 or more, or while performing a hot water treatment, using a heat conductive catalyst supporting a metal having catalytic activity, a combustible substance is used. To provide an oxidative combustion method using a thermally conductive catalyst, characterized by oxidizing and combusting. .

The material of the heat conductive carrier used in the present invention includes, for example, aluminum, magnesium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, titanium, zirconium, vanadium, copper, silver, zinc, bismuth, tin, A single metal or alloy plate made of lead or antimony, a metal plywood or spongy metal plate obtained by polymerizing multiple metal plates can be used, and those with an aluminum thin film adhered to their surface are used In particular, iron, copper, stainless alloy and aluminum are preferable in terms of economy and the like, but are not necessarily limited to these materials. Further, the shape may be any shape such as a plate shape.

The surface to which the catalyst is bound may be any suitable surface of the heat conductive carrier, and in order to improve the catalytic activity of the catalyst to be bound, the catalyst carrying activity is imparted to the roughened metal surface. After binding the fine particles, the catalyst material can be further supported.

At this time, if a spongy metal is used as the catalyst carrier,
The heat conduction of the catalyst carrier is increased, so that a very good catalyst having heat exchange can be obtained.

In addition, as a method for roughening the surface of the heat conductive carrier in the present invention, known methods such as ball dressing, mechanical methods such as graining, chemical methods such as etching, electrochemical methods such as anodic oxidation, etc. An appropriate method can be selected from the methods, and anodic oxidation is particularly preferable from the viewpoint of increasing the surface area.

The anodic oxidation is to make the potential of the anode a noble potential than the equilibrium potential to perform an oxidation reaction. Examples of the processing liquid used for the anodic oxidation include a chromic acid aqueous solution,
An oxalic acid aqueous solution, a sulfuric acid aqueous solution and the like can be mentioned.

The temperature of the processing solution is from room temperature to 50 ° C., especially from 30 to 40 ° C.
° C is preferable, and if the temperature is lower than room temperature, a dense film is formed.
If it exceeds 300, the dissolution is severe and it is difficult to form an oxide film economically.

In addition, in the case of this anodization, the processing time of the heat conductive carrier with the processing solution is preferably 1 hour or more, particularly 6 to 12 hours, and if it is less than 1 hour, the increase in surface area becomes insufficient, while 12 hours Even if it exceeds, the increase of the surface area cannot be expected, and it is economically disadvantageous.

Furthermore, when the above-mentioned spongy metal is used, the surface is roughened by etching or anodic oxidation.
Thus, the effective catalyst surface can be increased by roughening the surface supporting the catalyst.

The hot water and steam used in the present invention are heated water and steam for performing a heat treatment for increasing the surface area of the catalyst.

The temperature of this hot water and steam (heat treatment temperature) is 50 ~
The temperature is preferably 350 ° C., particularly preferably 50 to 150 ° C., and if it is lower than 50 ° C., the surface area of the catalyst body is insufficiently increased, while if it exceeds 150 ° C., the equipment cost increases and it is not economical.

Further, the pH of the hot water is preferably 7 or more, particularly preferably 10 to 12, and if it is less than 7, dissolution of the catalyst body occurs to decrease the surface area.

In addition, the treatment time of the hot water treatment of the heat conductive carrier is preferably 1 to 3 hours, particularly preferably 1 to 2 hours, and if it is less than 1 hour, the increase in surface area becomes insufficient, and even if it exceeds 3 hours. However, an increase in surface area cannot be expected, which is economically disadvantageous.

The metal having catalytic activity used in the present invention refers to a catalyst used for the thermally conductive catalyst, and its material is not particularly limited. For example, a platinum group metal,
It is preferable to select from a single metal such as gold, copper, nickel, manganese, iron, zinc, cobalt, or an alloy thereof, and it is particularly preferable to select from platinum, palladium, nickel and cobalt. Further, these catalyst substances can be combined.

In the present invention, the supporting of the thermally conductive carrier by the metal having catalytic activity is performed after or simultaneously with the heat treatment.

The method for supporting a metal having catalytic activity in the present invention is appropriately selected from known methods such as an electrodeposition method, a chemical deposition method, a vacuum deposition method, a cathode sputtering method, a metal spray method and a metal cladding method. Can be adopted. For example, in the case where an ultrafine platinum catalyst is supported on a catalyst carrier in which fine particles having catalyst supporting activity are bound on a roughened metal surface, the PH is 7 or more, preferably 11 to
Alternatively, a method of immersion in an aqueous solution of chloroplatinic acid (H ₂ PtCl ₄ ) of No. 13 may be employed.

Further, a catalyst can be supported on the roughened support surface through a two-step process.

That is, the first step is a step of binding fine particles having catalytic activity to the roughened surface.

When the catalyst material is supported on the metal surface to which the thus-obtained fine particles having the catalyst-supporting activity are bound, and then the ultrafine particles are supported on the metal surface, the ultrafine particles of the catalyst material are simply formed on the roughened metal surface. The catalyst activity can be remarkably improved as compared with the case where is carried.

The thermally conductive catalyst body thus manufactured is used for the oxidative combustion reaction of the fluid to be treated.

Examples of the fluid to be treated include flammable substances such as organic substances in factory exhaust gas, carbon monoxide other than the organic substances, and methane;
Other examples include acetone.

Further, the reaction temperature of the fluid to be treated in the oxidative combustion reaction is preferably room temperature or higher, particularly preferably 150 to 1,500 ° C. If the temperature is lower than room temperature, the reaction becomes insufficient. On the other hand, if it exceeds 1,500 ° C, the heat resistance of the material becomes a problem.

Further, if a cylindrical heat conductive carrier and / or a helical heat conductive carrier which is inserted into the cylindrical heat conductive carrier to form a helical flow path in the tube is used as the heat conductive carrier,
A relatively large contact area between the fluid to be treated and the catalyst body is obtained.
Therefore, the reaction efficiency of the fluid to be processed can be further improved.

The material of the tubular heat conductive carrier is the same as the material of the heat conductive carrier, and its shape may be any shape as long as it is a cylindrical body such as a cylinder or a rectangular tube.

Note that the surface of the tubular heat conductive carrier to which the catalyst is bound only needs to include at least the inner peripheral surface. Also, the same catalyst as that supported on the heat conductive carrier is used.

The helical heat conductive carrier is made of the same material as the heat conductive carrier and the tubular heat conductive carrier, and a catalyst is supported on a predetermined surface thereof.

This helical heat conductive support is formed by twisting a long rectangular metal plate in the longitudinal direction to form a helical shape, and binding the catalyst by the catalyst supporting method applied to the present invention as described above. It is a thing.

The shape of the helical heat conductive carrier is not limited to a plate shape, and may be, for example, a cross-sectional shape having an appropriate shape such as a circle, an ellipse, or a polygon. After being attached, it may be formed into a spiral shape by twisting, and further, a catalyst may be carried after binding fine particles such as alumina or silica.

The twist pitch of the spiral heat conductive carrier can be set as appropriate.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

As shown in FIG. 1, the heat conductive catalyst A used in the oxidizing and burning method using the heat conductive catalyst of the present invention has an inner peripheral surface of a cylindrical heat conductive carrier (heat conductive carrier) 10. Roughening, followed by heat treatment using hot water or steam at a predetermined temperature and PH, and then carrying a catalyst (metal having catalytic activity) 20 on the inner peripheral surface thereof. In this method, an oxidizing combustion reaction is performed by causing a fluid Z to be treated such as acetone to flow through the cylinder of the thermally conductive catalyst A. Thus, the tubular heat conductive carrier 10 on which the catalyst is supported
In order to heat-treat the inner peripheral surface of the catalyst, the contact area of the catalyst with the heat treatment fluid is larger than that of simply supporting the catalyst on the tubular heat conductive carrier 10, and therefore, the reaction efficiency of the fluid Z to be treated is further improved. Can be improved.

Next, as shown in FIG. 2, another thermally conductive catalyst B used in the oxidation combustion method using the thermally conductive catalyst of the present invention.
Is to roughen the front and back surfaces of the spiral heat conductive carrier (heat conductive carrier) 30, and then heat-treat it with hot water or steam at a predetermined temperature and PH. The helical flow path 40 is formed in the heat conductive tubular body 10 by inserting the catalyst 20 carrying the catalyst 20 into the tubular heat conductive carrier 10 carrying the catalyst 20.

In the method of the present invention, an oxidative combustion reaction is also performed by causing a fluid to be treated Z such as acetone to flow through the cylinder of the thermally conductive catalyst A in the same manner.

At this time, the flow of the fluid to be treated Z in the cylinder of the tubular heat conductive carrier 10 is caused by supplying the fluid to be treated Z into the cylinder from one opening of the tubular heat conductive carrier 10. Processing fluid Z
Is discharged from the other opening while being rotated along the spiral flow path 40 formed in the tubular heat conductive carrier 10. As a result, a turbulent flow of the fluid Z to be treated is generated in the cylinder of the tubular heat conductive carrier 10, so that the contact area between the fluid Z to be treated and the supported catalyst 20 is increased, and the fluid to be treated is further increased. The reaction efficiency of Z is improved.

At this time, since the catalyst 20 is also supported on the spiral heat conductive carrier 30 together with the cylindrical heat conductive carrier 10, the contact area of the fluid Z to be treated with the catalyst 20 is increased, and thus The reaction efficiency of the fluid Z is improved.

Further, the heat energy generated in the oxidative combustion reaction is transmitted to the tubular heat conductive carrier 10 and radiated to the outside.At this time, the catalyst is placed in the tubular heat conductive carrier 10 not supporting the catalyst 20. In the case where the helical heat conductive carrier 30 carrying 20 is inserted, a turbulent flow of the processing target fluid Z occurs in the cylinder of the cylindrical heat conductive carrier 10 as described above,
This turbulence promotes a decrease in the fluid film formed near the inner peripheral surface, and it is possible to further improve the thermal conductivity of the thermally conductive catalyst A.

Furthermore, when the catalyst 20 has deteriorated, the spiral heat conductive carrier 30 supporting the catalyst 20 can be taken out of the tubular heat conductive carrier 10 and recycled. Can be.

Next, as shown in FIG. 3, a thermal conductive catalyst C used in an oxidizing combustion method using the thermal conductive catalyst of the present invention is an outer peripheral surface of the cylindrical thermal conductive carrier 10. In addition, a large number of fins 11 are formed to increase the surface area to further improve the thermal conductivity of the tubular heat conductive carrier 10.

The fins 11 are formed in a hollow disk shape having good thermal conductivity, and a large number of the fins 11 are protruded at equal intervals in the cylinder axis direction on the outer peripheral surface of the cylindrical heat conductive carrier 10 inserted into the hollow portion. However, without being limited to this, any number may be formed in other shapes and other arbitrary intervals, for example. In this way, by providing a large number of fins 11 around the outer peripheral surface of the cylindrical heat conductive carrier 10, the heat conduction coefficient increases through the fins 11, thereby further increasing the cylindrical heat conductive carrier 10. The thermal conductivity is improved.

[Action]

The catalytic reactant of the present invention first roughens the surface of the thermally conductive carrier, and then performs heat treatment using hot water or steam at 50 to 350 ° C. and PH of 7 or higher, or performs catalytic activity while performing the heat treatment. By supporting a metal having the following formula, the surface of the heat conductive carrier is eroded, and the surface area of the heat conductive carrier is substantially increased.

Next, by performing an oxidative combustion reaction using the thermally conductive carrier having the increased surface area, the contact area between the metal having catalytic activity and the fluid to be treated is increased, and the reaction of the fluid to be treated is further increased. Efficiency can be improved.

Further, in the case where a cylindrical heat conductive carrier and / or a helical heat conductive carrier which is inserted into the cylindrical heat conductive carrier and forms a helical flow path in the tube is used as the heat conductive carrier. When the fluid to be treated is supplied into the cylinder from one opening of the tubular heat conductive carrier, the fluid to be treated is formed straight along the inner peripheral surface of the cylinder or formed in the thermally conductive cylinder. While being rotated along the spiral flow path, it flows out of the other opening. For this reason, the contact area between the fluid to be treated and the catalyst is increased, and the reaction efficiency of the fluid to be treated is improved.

When a helical heat conductive carrier is used, a turbulent flow of the fluid to be processed is generated in the heat conductive cylindrical body, and therefore, the flow of the fluid to be processed and the catalyst supported on the catalyst body are generated. The contact area is increased, and the reaction efficiency of the fluid to be treated is further improved.

Furthermore, when this helical heat conductive carrier is used, the heat energy generated in the exothermic or endothermic reaction is conducted outside through the heat conductive cylinder,
At this time, as described above, the turbulent flow of the fluid to be processed is generated in the heat conductive cylindrical body, and this turbulent flow promotes the reduction of the fluid film formed near the inner peripheral surface, and the heat conductive property is increased. The thermal conductivity of the cylinder is improved.

Furthermore, when a heat conductive cylinder is also used as the heat conductive catalyst in addition to the spiral heat conductive carrier, a catalytic reaction of the fluid to be treated also occurs on the peripheral surface of the cylinder, and therefore, the fluid to be treated is Has a larger contact area with the catalyst body, which further improves the reaction efficiency of the fluid to be treated.

Also, when a helical heat conductive carrier is used, even when the catalyst has deteriorated, only the catalyst body is extracted, and after regenerating, the catalyst body is inserted again into the heat conductive cylinder to thereby reduce the catalyst body. It can be easily recycled.

〔Example〕

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings, but the present invention is not limited to these embodiments.

Examples 1 and 2 A case where only the tubular heat conductive carrier shown in FIG. 1 was used as the heat conductive catalyst (Example 1), and a case where the helical heat conductivity was contained in the tubular heat conductive carrier shown in FIG. A carrier was inserted, all of which were used as heat conductive catalysts (Example 2), acetone (600 ppm / air) was used as a fluid to be treated, and the reaction temperature was 150.
The oxidation combustion reaction was performed under the reaction conditions of ~ 240 ° C and a flow rate of 0.35 to 1.20 / min.

The preparation of the tubular heat conductive carrier and the helical heat conductive carrier was carried out in an anodized 2.5 wt% chromic acid aqueous solution for 6 hours.
Liquid temperature 38 ° C, current density 19.0A / m ² Baking 350 ° C, 1 hour, Platinum-supported in air 2.5g-Pt / ml Chloroplatinic acid hot aqueous solution (Hot water treatment) pH 11, 2 hours Hydrogen reduction 200 ° C, 2 hours Met.

Table 1 shows the physical properties and reaction rate of the catalyst at this time. FIG. 4 shows the relationship between the contact time-temperature of the fluid to be treated and the catalyst in this oxidative combustion reaction and the removal rate, and FIG. 5 shows the relationship between the contact time and the removal rate in this oxidative combustion reaction. .

As is evident from Table 1, it is clear that the surface area of the catalyst has been increased about 5 times by the heat treatment. Further, as is apparent from FIG. 4, it is possible to perform oxidative combustion completely at 300 ° C. or lower.

Further, as is apparent from FIG. 5, the use of the helical heat conductive carrier increases the catalytic activity per reaction tube volume.

[Effects of the Invention] The present invention thus roughens the surface of the heat conductive carrier, and then performs a hot water treatment using hot water or steam having a temperature of 50 to 350 ° C. and a pH of 7 or more, or hot water. By performing an oxidative combustion reaction using a thermally conductive catalyst body carrying a metal having catalytic activity while performing the treatment, the surface area of the thermally conductive carrier on which the metal having catalytic activity is carried increases, Therefore, the effect that the reaction efficiency of the fluid to be treated is improved is obtained.

Further, when a tubular heat conductive carrier and / or a spiral heat conductive carrier which is inserted into the tubular heat conductive carrier and forms a spiral flow path in the tube is used as the heat conductive carrier. Is because the surface of the heat conductive carrier on which the metal having catalytic activity is supported is a circumferential surface, so that the surface area of the heat conductive carrier is increased, and the reaction efficiency of the fluid to be treated is further improved. Is obtained.

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional view of a heat conductive catalyst used in the oxidation combustion method using the heat conductive catalyst of the present invention, and FIG. 2 is oxidative combustion using the heat conductive catalyst of the present invention. FIG. 3 is a central longitudinal sectional view of another heat conductive catalyst used in the method, and FIG. 3 is a center view of still another heat conductive catalyst used in the oxidation combustion method using the heat conductive catalyst of the present invention. It is a longitudinal cross-sectional view. FIG. 4 is a graph showing the relationship between the contact time between the fluid to be treated and the catalyst in the oxidizing combustion reaction, the temperature and the removal rate, and FIG. FIG. A, B, C; thermal conductive catalyst Z; fluid to be treated 10; tubular thermal conductive carrier (thermal conductive carrier) 20; catalyst (metal having catalytic activity) 30; helical thermal conductive carrier (heat Conductive carrier) 40; spiral channel

────────────────────────────────────────────────── ⁶ Continuation of the front page (51) Int.Cl. ⁶ Identification code FIF23G 7/06 102 B01D 53/36 103Z (56) References JP-A-2-144154 (JP, A) JP-B-52-48594 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01J 21/00-38/74

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the surface of the heat conductive carrier is roughened.
After a heat treatment using hot water or steam at a temperature of 50 to 350 ° C. and a pH of 7 or more, or while performing a hot water treatment, using a heat conductive catalyst supporting a metal having catalytic activity, a combustible substance is used. Oxidizing combustion using a thermally conductive catalyst, characterized by oxidizing combustion. 2. As the heat conductive carrier, a cylindrical heat conductive carrier and / or a helical heat conductive carrier which is inserted into the cylindrical heat conductive carrier to form a spiral flow path in the tube is used. An oxidative combustion method using the thermally conductive catalyst according to claim 1.