JPH07500559A - Method for producing hydrogen peroxide - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method for producing hydrogen peroxide The present invention relates to the production of hydrogen peroxide by the so-called anthraquinone method, and more precisely relates to the hydrogenation method in the process.

Hydrogen peroxide is known to be produced by the so-called anthraquinone method. . In this method, anthraquinone derivatives are added to a solvent containing - or more components. be dissolved. The solution thus prepared is called a working fluid. In the production of hydrogen peroxide , the working fluid is first sent to a hydrogenation process. In this process, anthraquinone derivatives are It is hydrogenated in the presence of a medium to give the corresponding anthrahydroquinone derivative.

The working fluid is then sent to an oxidation step where the anthrahydroquinone derivative is or oxidized with oxygen. Hydrogen peroxide is thus produced and anthrahydroquino The anthraquinone derivative is converted to the form before hydrogen is added, i.e., anthraquinone derivative. Ru. The working fluid containing hydrogen peroxide is sent to an extraction process where hydrogen peroxide is added to the working fluid. extracted from and transferred to an aqueous solution. After extraction, the hydraulic fluid is dried from excess water. It is then returned to the first step of the circulation process, the hydrogenation process. Hydrogen peroxide obtained by extraction Water is purified and concentrated.

Different types of suspension reactors and fixed bed reactors are used for the hydrogen peroxide process. It is used in the oxidation process. Comparing these glue actors, we find that the most important base is One of the criteria is the production amount calculated in proportion to the volume of the reaction solution, or the unit amount of catalyst. Ru. Another important criterion is the high selectivity of the hydrogenation, i.e. the high selectivity between the main and side reactions. is the desired rate of conversion. In addition, high yields can be obtained by minimizing excess hydrogen. It is also important to obtain intrahydroquinone derivatives. Take into account when comparing Other factors that must be included include auxiliary means for hydrogenation, e.g. in catalytic filtration. and differences in the steps to continue the hydrogenation, e.g. regeneration of the catalyst. be caught. Thus, many criteria are essential for comparison. And conventional glue Few of the stars are the best in all respects. Relatively broad perspective for comparison Of course, consider the total cost of the hydrogenation process.

Reactor yield and selectivity are primarily determined by hydrogenation pressure and temperature, reactant content, catalyst depends on the amount and activity of , mixing conditions, and retention time of the reaction mixture in the reactor. . The reaction rate itself depends to a large extent on the properties of the catalyst. In addition to the reaction rate Therefore, the hydrogenation rate also depends on the transition of materials, especially hydrogen from gas to liquid, and also on the surface of the catalyst. affected by metastasis to. Therefore, favorable conditions are very important for material transfer. It is. In terms of hydrogenation yield and selectivity, there are optimal conditions for hydrogenation pressure and temperature. Ru. In order to perform hydrogenation under conditions as close as possible to those conditions, the reactor It is preferable to keep fluctuations in pressure and temperature within the range as small as possible.

Porous so-called palladium charcoal or Raney nickel (Raney nickel) is used, or a carrier (active Palladium fixed on charcoal, aluminum oxide) is also used. Suspension contact If a medium is used, the reactor may be of the type, for example a mixing vessel.

In addition, the suspension reactor operates on the so-called mammoth pump principle (air pump). Ift) (UK Patent Specification No. 718.307) It is. Furthermore, in pipe reactors, turbulence (U.S. Patent Specification No. 4.428.923) and pipe diameter differences (U.S. Patent Specification No. No. 3,423,176), or static mixer (static m1xer) It is also known that mixing occurs according to Finland Patent Application No. 864.971). ing.

There are some disadvantages to suspension reactors compared to fixed bed reactors. be. First of all, when using suspension catalysts, efficient filtration is required after hydrogenation. It becomes important. This is because the catalyst must not be mixed into the oxidation process. This filtration are often very expensive and require complex flow equipment, making them technically difficult to There's a problem. Filtration is also hampered by very small catalyst particles.

When using a suspension reactor, most of the expensive catalyst is stored somewhere other than within the reactor. They are often located elsewhere, such as in filtration equipment, circulation pipes, or pipe systems.

Some of the catalyst may adhere to the solid surfaces of these devices for long periods of time, resulting in Only a portion of is present in the reaction space and is only used. i.e. catalyst efficiency is inferior.

A third disadvantage of suspension reactors is that the catalyst is highly susceptible to mechanical wear. That's a good thing. This is because in fixed bed reactors the catalyst usually reduces its activity to a suspension catalyst. This may contribute somewhat to the fact that it lasts longer.

In a fixed bed reactor, the catalyst is fixed inside a solid support structure. If there is, these three disadvantageous factors do not exist. A typical fixed bed reactor is , having a layer of particles with a diameter typically between 0.2 and 10 mm. The carrier within this particle is , with wide special surfaces such as aluminum oxide, activated carbon or silica gel It is a porous material. The support is a precious metal, usually palladium, as the catalyst component. impregnated as In hydrogenation, the working fluid and hydrogen flow through a catalyst bed.

In the above fixed bed reactor, the hydrogenation efficiency decreases due to several factors. Mau. First, the transition of hydrogen from gas to liquid and then from the liquid to the surface of the catalyst occurs. This type of device is not very fast. As a further addition, the catalyst bed is The structure is such that it can happen easily. In other words, gas and liquid are each They are separated while maintaining their original state. This allows for the transfer of substances within the reactor. It becomes late. Furthermore, in this type of catalyst bed, only the catalyst on the surface of the support is efficient. The problem is that the transfer of substances into the pores of solid particles is slow because they are not used for be.

To more easily dissolve hydrogen, U.S. Pat. A fixed bed reactor has been described in which media and inert support layers alternate. Its origin In the light, the volume of the reactor inevitably becomes large, so expensive hydraulic fluid is not used. The volume will also increase.

In addition, to more efficiently dissolve the hydrogen, the working fluid is transferred to a separate tube before the reactor. (U.S. Pat. No. 2,837,411). . Even with this invention, the volume of hydraulic fluid will increase. Furthermore, pre-melting benefits are limited. Because – more than the amount that can be dissolved in the hydraulic fluid at a time This is because a large amount of hydrogen is consumed many times in the reaction. For the same reason, rear U.S. Patent No. The benefits derived from the invention disclosed in No. 4,428.922 are also very limited. It's fleeting.

Fixed bed reactors use differently shaped catalyst fragments instead of round support particles. Good too. One way is to use so-called honeycomb structures. In this case, Catalyst fragments consist of solid structures made up of bundles of parallel through channels. So The diameter of the flow path is, for example, 0. It is 5 to 10 mm. The thickness of the wall separating the channels is For example, it is 0.03 to 1 mm. The catalyst, e.g. palladium metal, is fixed to the wall of the channel be done.

European Patent Specification No. 41.814 discloses a method using the above-mentioned honeycomb structure. A method is shown. In the above method, the honeycomb-structured catalyst fragments are used as reactants. are arranged irregularly in the pipes of the reactor through which they flow. What about actors like this? Even if you add the catalyst in two different states i.e. gaseous and liquid peroxide water It is not very suitable for cases such as elementary method hydrogenation. Mixing inside the pipe is efficient It is not sufficient to provide liquid dispersion or to dissolve the gas in the liquid. this In the flow path of the honeycomb structure used in this way, gas molecules are converted to liquid, and Flow conditions are also not provided to cause rapid transfer to the catalyst surface. This type of paste When using the reactor as a gas-liquid reactor, there is a risk that the supply cannot be controlled. There is.

In U.S. Pat. No. 4,552,748, honeycomb structures are manufactured using a hydrogen peroxide process Used in hydrogenation reactors. Here we have - or more - inside the reactor. A catalyst bed is constructed by arranging the honeycomb-shaped catalyst pieces above. The result As a result, the fragments come together, have equal lengths, are parallel to each other, and are flat in the direction of fluid flow. A plurality of flow channels are formed. The catalyst is fixed as a thin film on the wall of the channel. operation The liquid is circulated several times within this reactor, preferably in parallel with the hydrogen.

Problems inevitably arise when applying the above-mentioned patented reactor on a manufacturing scale. . The first of these concerns thermal transitions. The hydrogenation reaction of the hydrogen peroxide method is exothermic. Therefore, the temperature inside the reactor tends to rise. The temperature is particularly high inside the honeycomb structure. It tends to rise in the middle. Because heat transfers slowly outward from there. It is. Therefore, the catalyst structure cannot be made too long. The temperature inside the reactor is This is because uniformity is not desirable for several reasons. On the other hand, if the catalyst structure If is made too short, its diameter will be large enough to obtain one volume of the actor. I have no choice but to do so. The large diameter catalyst structure then circulates within the actor. A disadvantage arises in that the flow of hydraulic fluid used is too large. Another obstacle The damage concerns the uniform distribution of liquids and gases proportional to the cross section. In the above-mentioned known patent The diameter of the flow path is preferably 1 to 2 mm. Crossing liquid and gas mixtures It is difficult to distribute the liquid and gas proportionally to the surface, so the liquid and gas flow approximately through each flow path. It will flow at the same rate. This causes non-uniform hydrogenation and In some channels, hydrogenation is prolonged, while in other channels it remains at a low level. There are some places. As a result, both selectivity and average yield decrease. Countercurrent reactor question Is it a problem with co-current reactors that operate from top to bottom or in opposite directions? If so, it would be difficult to distribute the liquid and gas bubbles evenly.

No. 4,552,748 to operate the reactor. The third fact concerns the amount of gas and liquid in the flow path. The total amount of hydrogenation in the flow path is Depends on the transfer rate and reaction rate. In some cases, the so-called slug flow or Different types of flow may exist, such as bubble flow. Depending on the type and conditions of flow in the flow path. Therefore, there is a most desirable ratio of gas and liquid to obtain the highest total amount of hydrogenation. . The volume of gas that continues to move in the flow path is decreasing due to the reaction result, so the gas and liquid The body flow rate varies as a function of pipe length. Therefore, if flow If path lengths are equal, operate near the most desirable ratio of gas and liquid flow rates. is not possible.

In the present invention, since a fixed bed type reactor is used, there are no drawbacks as mentioned above. , the effect is as small as possible. The features of the invention are set out in the appended claims. It is.

That is, the method for producing hydrogen peroxide of the present invention involves using hydrogen or a gas containing hydrogen. This is a method for producing hydrogen peroxide using the anthraquinone method, which performs hydrogenation through mediated action. Therefore, hydrogen or hydrogen-containing gas, and the hydraulic fluid are assembled from solid honeycomb parts. The solid catalyst layer is circulated downward from above through the vertically erected solid catalyst layer. has multiple channels parallel to the actor pipe and multiple channels perpendicular to this direction. , a material having a catalytic action is fixed to the walls of the plurality of channels, and each catalyst At the lower end of the layer there is a mixing section, for example a static mixer (static m1xer). characterized by something.

In the above configuration, the catalyst layer is divided into many layers, and the liquid flow between the different layers is It is preferably redistributed in the transverse direction using a suitable liquid distributor, e.g. a distribution plate. Delicious.

Further, in the above configuration, the entire component of the mixing section is covered with the catalytically active material. is preferable.

Further, in the above configuration, the atmospheric pressure inside the reactor is 1 to 15 bar, preferably 2 to 6 bar and the temperature in the reactor is below 100°C, in particular 40 to 60°C It is preferable that

The structure of a hydrogenation reactor according to the present invention is illustrated in FIG. First, the reactor is water A circulation container 1 is provided for containing a working fluid 9 to be purified. The hydraulic fluid to be hydrogenated is It can also be fed directly into the hydrogenation cycle 5. One or more hydraulic fluids are supplied from the circulation container 1. is further circulated several times through the actor pipe 2 and pump 3. hydrogenated The working fluid 12 is further sent from the circulation container 1 to an oxygen treatment process.

Surrounded by the outer wall 4 or inside the actor pipe 2, the working fluid 9 and hydrogen 8 are distributed from top to bottom. flowing parallel to. The catalyst layer 11 in the pipe is parallel to the flow, that is, vertically The flow path has a plurality of channels perpendicular to the flow. the plurality of channels The walls are covered with a porous layer of a durable carrier with a layer thickness of 5 to 300 μm.

The porous support is aluminum oxide, silica, silicate and/or activated carbon. Good too. The support structure of the catalyst layer is a metal plate or foil with a thickness of 20 to 1000 μm. made of. Similarly, ceramic structures may also be used. Catalytic materials, e.g. The radium is fixed on the walls of the plurality of channels, i.e., it is adsorbed on the surface of the porous carrier. It is. In addition to palladium, examples of catalyst materials include rhodium and ruthenium. aluminum, nickel or mixtures thereof may also be used. The catalyst layer is preferably There are several layers. If the catalyst layer is several layers, liquid distributors between the different parts, e.g. There is a sieve plate 10. A cylindrical wall 7 is connected to the distribution plate 10. The liquid may be collected in layers on a distribution plate. The hydraulic pressure of this liquid layer As a result, the liquid is distributed as a liquid to the tag on the distribution plate.

If there are several catalyst layers, a mixing section, e.g. a static mixer, is installed at the bottom of each layer. A device 6 may also be provided. This mixing section distributes the liquid evenly over the cross section and to equalize the transverse temperature gradient. In addition, the structural parts of the mixing section are catalytically active. May be covered with material. Problems caused by temperature rise are especially noticeable along the central axis of the pipe. For this reason, it is preferable that the mixing section be located at the center of the catalyst layer, as shown in FIG.

The reactor pipe 2 may be provided with a cooling jacket or other cooling device.

The pressure in the reactor during hydrogenation is between 1 and 15 bar, preferably between 2 and 6 bar. Ru. The temperature is kept below 100<0>C, the preferred hydrogenation temperature being 40-60<0>C.

When we conducted an experiment using the above glue actor structure, we surprisingly found that the following two things occurred. The fact has become clear.

First, the catalyst layer is divided into several layers, between which liquid distributors, such as dispersion plates, etc. The presence of a mixing section makes the reactor work more efficiently.

Second, there are channels parallel to the flow (i.e. vertical) and channels perpendicular to the flow (i.e. A catalyst layer with flat flow channels has a higher brightness than a catalyst layer with only flow channels parallel to the flow. Clearly efficient.

These two observations are clearly demonstrated by the following examples. Observation mentioned above The results mainly concern cross-sections and to some extent parameters in the glue actor of the invention. If we can obtain more uniform conditions than the closest similar invention on the vertical axis of brought about by physical and chemical reasons based on the fact that

In the examples described below, Examples 1 and 2 are similar to each other. with them The support material layers used were of the same thickness and optimized, with palladium content. The prevalence was also the same. Also, Examples 3 and 4 are similar to each other. because that This is because similar support material layers and the same palladium content were used in the Ru. The support material layer and palladium content used in Examples 3 and 4 were adjusted to the optimum conditions. The deviation was significantly greater than that of Examples 1 and 2.

Example 1 In experiments conducted on a small scale, ethyl anthraquinone and tetrahydroethyl anthraquinone mixtures with laquinone and also aromatic hydrocarbons and organic phosphorus compounds as solvents. A hydraulic fluid containing a compound was used. The reactor is of the invention, parallel to the main flow (i.e. In other words, there are multiple channels that are vertical (i.e., vertical) and multiple channels that are perpendicular (i.e., horizontal) to the main stream. It was equipped with a catalyst layer having . The catalyst structure has a porous gamma oxidation surface. Consisted of a metal support structure with thin walls to which aluminum support material was fixed . Aluminum oxide was impregnated with palladium. The height of the catalyst layer is 2500mm It was divided into three parts. A distribution plate is used as a liquid distributor between the parts. It was. At the lower end of each catalyst bed was a mixing section consisting of a static mixer. This experimental configuration is Used continuously. The unhydrogenated hydraulic fluid is reared at a rate of 60 liters/hour. the same amount of product was removed. Circulation inside the reactor is a downward flow path The velocity of the liquid inside was 0.09 m/sec. The temperature inside the reactor is 50℃, the pressure was 4.0 bar. Volume of hydrogen in the reaction mixture at the top of the reactor pipe Hydrogen was sent to the reactor in an amount to give a percentage of 20%. reactor without reaction - Hydrogen remaining in the pipe was immediately removed. Under these conditions, the yield of glue actors is 2 06kgH2O2/(kgPd1Ih).

Example 2 In this comparative experiment, a catalyst layer with only vertical channels and no horizontal channels was used. was used. In other respects, the experimental conditions and experimental reactor were exactly the same as in Example 1. be. In particular, the amount of palladium in the reactor is similar to the amount of hydrogen sent to the reactor. It was made exactly the same as in Example 1. The yield of the reactor is 198 kg H2O2/(k g Pd-h). When the proportion of hydrogen in the reaction mixture is less than 20% by volume, The yield of the reactor of Example 2 is clearly inferior to that of the reactor of Example 1. there was.

Example 3 The experimental reactor used in this comparative experiment was characterized by the layer thickness of the porous support material and the The actual conditions were different from those in Example 2 and the conditions were not favorable. It was the same as that used in Example 2. In other respects, the experimental conditions were the same as in Example 2. It is the same. When the hydrogen sent is 20% of the volume of the reaction mixture, 104 kgH20 A yield of 2/(k g P dh) was obtained. Percentage of hydrogen is 10 bodies When the product is %, a yield of 87 k g H2O2/(k g P d・h) is obtained. It was. These results were compared with those of Example 4.

Example 4 The catalyst bed used in this comparative experiment was a single catalyst bed, not divided into multiple parts. It was the same as that used in Example 3 with one exception. Therefore, between the catalyst layers There was no dispersion plate as a liquid distributor or mixing section. The amount of palladium is also different from other glues. The detailed structure of the actor and the test conditions were the same as in Example 3. hydrogen supply When the reaction mixture is 20% by volume, the yield is 90 kg H202/(k g Pd・h). Also, when the hydrogen supply is 10% by volume, the yield is 60k g H202/(kg Pd-h).

Figure 1 international search report international search report Continuation of front page (72) Inventor Makiniemi Nisco Kellostier 2, Nisev-90940, Jari, Finland (72) Inventor Maunula Teupo Mill Ojantier 13, Nisev-90650, Oulu, Finland -33

Claims (4)

[Claims] 1. Anthracite, which performs hydrogenation by catalytic action using hydrogen or hydrogen-containing gas. In the non-method production of hydrogen peroxide, hydrogen or hydrogen-containing gas, and and hydraulic fluid from top to bottom through a solid catalyst layer assembled from solid honeycomb parts. The catalyst layer circulates in the main sink or with a plurality of channels parallel to the reactor pipe. , having a plurality of channels perpendicular to this direction, and having a catalytic effect on the walls of the plurality of channels. In addition, at the lower end of each catalyst layer there is a mixing section, e.g. A method for producing hydrogen peroxide characterized by the presence of a static mixer Law. 2. The catalyst layer is divided into many parts, and the liquid flow between the different parts is controlled by, for example, a dispersion plate. claim characterized in that the liquid is redistributed in the transverse direction using a suitable liquid distributor such as Item 1. The method for producing hydrogen peroxide according to item 1. 3. Claim 1 characterized in that the entire component of the mixing section is covered with a catalytically active material. The method for producing hydrogen peroxide described in . 4. the pressure inside the reactor is between 1 and 15 bar, preferably between 2 and 6 bar; Characterized by the temperature inside the reactor being less than 100°C, preferably 40-60°C The method for producing hydrogen peroxide according to claim 1, 2 or 3.