JP2003340267A - Method for packing catalyst and multitubular heat exchange type reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for packing a catalyst in a multitubular heat exchange type reactor which can improve a yield and a conversion ratio in a catalytic gas-phase oxidation reaction and a reaction rate, and the multitubular heat exchange type reactor. <P>SOLUTION: In the method for packing the catalyst into a number of reaction tubes 12, 12, 12, and the like, the quantity of the catalyst to be packed in each tube 12 is controlled to be within a target quantity of the catalyst ±10%, and the length of a part of each tube 12 where the catalyst is packed is controlled to be within a target length ±20%, or the pressure loss of each tube 12 is controlled to be within a target pressure loss ±20%. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst filling method for filling a reaction tube with a fixed bed catalyst and a multi-tube heat exchange reactor filled with the catalyst by the method.

[0002]

2. Description of the Related Art For example, when acrolein or acrylic acid is industrially produced from propylene or when methacrolein or methacrylic acid is industrially produced from isobutylene, a large number of reaction tubes are provided. A catalytic gas phase oxidation reaction using a multi-tube heat exchange type reactor is sometimes performed. In this catalytic gas-phase oxidation reaction, the raw material gas and molecular oxygen are circulated through the fixed bed oxidation catalyst packed in a large number of reaction tubes, and the outside of each reaction tube is heated or removed by a heat medium. This promotes the oxidation reaction.

By the way, in the reaction in the multi-tube heat exchange type reactor, it is preferable that the gas flow rates of a large number of reaction tubes are uniform in order to make the reaction uniform. However, in the conventional multitubular heat exchange type reactor, the control of the catalyst filling was not always sufficient. For example, even if the tube diameter is uniform and the amount of catalyst is the same, the packing density of the catalyst may differ between reaction tubes, which results in different pressure loss between reaction tubes and uneven gas flow rates. There was a chance When the gas flow rate becomes non-uniform, the contact time, which is the reaction time, becomes non-uniform, which causes variations in the reaction in each reaction tube.
There was a case where the side reaction could not be controlled, the yield was lowered, the total reaction rate was lowered, etc., and the productivity was lowered. Therefore, for example, in a hydrogenation reaction using a multi-tube heat exchange reactor, by controlling the pressure loss of each reaction tube filled with a fixed bed catalyst within a certain range, A method has been proposed in which the gas flow rate is made uniform to prevent variations in the reaction among the reaction tubes (JP-A-5-27).
9269).

[0004]

However, in this method, in order to keep only the pressure loss of each reaction tube within a certain range, the catalyst filling amount may be changed for each reaction tube. Therefore, although the gas flow rate is uniform, the catalyst filling amount is not uniform and the catalyst load is not uniform, so the reaction is not uniform among the reaction tubes, and the decrease in yield and the decrease in reaction rate are prevented. Was difficult. In particular, in the case of a gas-phase catalytic oxidation reaction for producing acrolein, acrylic acid, methacrolein, methacrylic acid, etc., the reaction heat is very large, so if the catalyst filling amount differs for each reaction tube, the catalyst layer in the reaction tube There is a problem in that the temperature of 1 changes greatly depending on the reaction tube, and the yield and the reaction rate also change greatly. That is, in the gas-phase catalytic oxidation reaction, it is not possible to make the reactions in a large number of reaction tubes uniform by simply setting the pressure loss of each reaction tube within a certain range, and as a result, the productivity is sufficiently improved. I couldn't do it.

According to the present invention, even in a gas phase catalytic oxidation reaction for synthesizing acrolein, acrylic acid, methacrolein, methacrylic acid, etc., which has a large heat of reaction, the contact time and the catalyst load of each reaction tube are made uniform, and the yield and An object of the present invention is to provide a method for charging a catalyst into a reaction tube of a multitubular heat exchange reactor and a multitubular heat exchange reactor capable of improving the reaction rate.

[0006]

As a result of intensive studies to solve the above problems, the present inventors have made the gas flow rate of each reaction tube within a certain range to make the contact time between each reaction tube uniform, and By making the amount of catalyst in each reaction tube within a certain range and making the catalyst load between each reaction tube uniform, reaction heat such as gas phase catalytic oxidation reaction for synthesizing acrolein, acrylic acid, methacrolein, methacrylic acid, etc. The inventors have found that even in a very large reaction, the yield and the reaction rate can be made uniform, and the production efficiency can be improved, and the following inventions have been completed. That is, the method of filling a catalyst according to claim 1 of the present application is a method of filling a catalyst in which a plurality of reaction tubes having substantially the same shape are filled with the catalyst. Weigh it within the range and fill the catalyst into each reaction tube so that the difference between the filling length of each reaction tube and the average value of those filling lengths is within ± 20% of the average value of the filling length. It has a feature. Here, the filling length is the length of the portion filled with the catalyst when the reaction tube is filled with the catalyst. In the present invention, the term "catalyst" includes not only ordinary catalysts but also catalyst diluents used for adjusting the reaction strength of catalysts and all those that can be filled in the reaction tube.

The catalyst filling method according to claim 2 of the present application is
In a catalyst filling method for filling a large number of reaction tubes of substantially the same shape with a catalyst, the catalyst to be filled in each reaction tube is weighed within ± 10% of a control target amount, and the pressure loss of each reaction tube is It is characterized in that each reaction tube is filled with a catalyst so that the difference from the average value of the pressure loss is within ± 20% of the average value of the pressure loss.

The catalyst filling method according to claim 3 of the present application is a catalyst filling method in which a large number of reaction tubes having substantially the same shape are filled with the catalyst. % So that the difference between the filling length of each reaction tube and the average value of those filling lengths is within ± 20% of the average value of the filling length, and the pressure loss of each reaction tube and the pressure It is characterized in that each reaction tube is filled with the catalyst so that the difference from the average value of the loss is within ± 20% of the average value of the pressure loss.

In the above-mentioned catalyst packing method, when the number of reaction tubes is 50 or more, the number of reaction tubes is 10 or more and is a natural number in the range of 0.5 to 99.5% of the total number of reaction tubes. It is preferable that the reaction tubes are extracted, and the value obtained by averaging the filling lengths of the extracted reaction tubes is set as the average value of the filling lengths.

When the number of reaction tubes in the multi-tube heat exchange type reactor is 50 or more, it is 10 or more and from a natural number in the range of 0.5 to 99.5% of the total number of reaction tubes. It is possible to extract a certain number of reaction tubes and average the pressure loss of the extracted reaction tubes to be the average value of the pressure loss. Further, the reaction tube can be divided into two or more groups so that the number of reaction tubes is approximately the same, and the same number of reaction tubes are extracted from each group to obtain the average value of the filling length and / or the average value of the pressure loss. Further, in the catalyst filling method of the present invention, each reaction tube can be filled with the catalyst twice or more.

The multi-tube heat exchange type reactor of the present invention is characterized in that the reaction tube is filled with the catalyst by the above-mentioned catalyst filling method. In the multitubular heat exchange reactor of the present invention, an acrolein synthesis reaction of reacting propylene with molecular oxygen to synthesize acrolein and / or a reaction of acrolein with molecular oxygen to synthesize acrylic acid. It is preferably used for acrylic acid synthesis reaction. Further, the multitubular heat exchange reactor of the present invention is a methacrolein synthesis reaction in which isobutylene or tertiary butyl alcohol is reacted with molecular oxygen to synthesize methacrolein and / or methacrolein and molecular oxygen. It is preferably used in a methacrylic acid synthesis reaction in which methacrylic acid is reacted to synthesize methacrylic acid.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the method for filling a catalyst and the shell-and-tube heat exchange reactor of the present invention will be described. In this embodiment, a methacrolein synthesis reaction using isobutylene and / or tertiary butyl alcohol and molecular oxygen as raw materials is performed. First, the multi-tube heat exchange reactor of the present invention will be described with reference to FIG. This multi-tubular heat exchange reactor 10 includes a large number of reaction tubes 12, 12, 12, ... Filled with a catalyst 11, a raw material gas inlet 13 provided in the lower part of the reactor, and an upper part of the reactor. The obtained reaction product outlet 14, a heat medium inlet 15 for introducing a heat medium for heating or removing heat from the reaction tube 12 into the reactor, and a heat medium outlet 16 for discharging the heat medium from the inside of the reactor, A baffle plate 17 of a notch type that prevents a shortcut of the flow of the heat medium is provided. In this multitubular heat exchange reactor 10, a large number of reaction tubes 12, 12,
12 ... have substantially the same shape. The “substantially the same shape” means that the difference in shape is such that the outer diameter, wall thickness, and length of the reaction tube are within the design error range. If the shapes are not substantially the same, the flow path resistance in the reaction tube becomes non-uniform, and the gas flow rate between the reaction tubes becomes non-uniform.

In the synthesis of methacrolein using such a multitubular heat exchange reactor 10, first, a raw material gas containing isobutylene and / or tertiary butyl alcohol and molecular oxygen is fed into the raw material gas inlet 13 To the multi-tubular heat exchange reactor 10. Then, in each reaction tube 12 filled with the catalyst 11 and heated by the heat medium,
Distribute the source gas. Then, when the raw material gas flows through the catalyst 11 from the bottom to the top, isobutylene is oxidized and / or tertiary butyl alcohol is dehydrated and oxidized to generate methacrolein. Then, the reaction product containing methacrolein is discharged from the reaction product outlet 14 to the outside of the multitubular heat exchange reactor 10.

The reaction tube 1 of the multitubular heat exchange reactor 10
When 2 is filled with the catalyst 11, the control target amount of the catalyst 11 is measured for each reaction tube or each filling time, and the measured catalyst is filled in each reaction tube 12 from the upper opening. Here, the management target amount may be a volume or a mass, but it is preferable to measure by the mass because the accuracy is high. When the control target amount is a volume, the amount is easily calculated from the volume of the reaction tube 12, and when it is a mass, it is easily calculated from the volume of the reaction tube 12 and the catalyst packing density separately preliminarily measured. Also,
When measuring the catalyst, the amount of catalyst filled in each reaction tube,
The difference from these control target amounts is ± 10% of the average value of the catalyst amount.
Within, preferably within ± 5%. If the difference between the amount of catalyst filled in each reaction tube and the control target amount is not within this range, the catalyst load between the reaction tubes becomes uneven. In addition, before the reaction tube 12 is completely filled with the measured catalyst 11,
When the reaction tube 12 is filled, a filling error due to a catalyst bridge or the like in the reaction tube 12 may occur, so that the reaction tube 12 needs to be refilled with the catalyst.

When the catalyst 11 is filled, the difference between the filling length of each reaction tube and the average value of the filling length is set within a certain range. That is, the ratio of the difference between the filling length of each reaction tube and the average value of the filling length with respect to the average value of the filling length (this ratio is also referred to as the control width) is within ± 20%, preferably ± 1.
Within 5%, more preferably within ± 10%, and most preferably within ± 5%. In this way, catalyst packing mistakes due to catalyst bridging and crushing can be easily found, and the catalyst packing density of all reaction tubes can be made uniform. If the filling length deviates from the control width, the reaction between the reaction tubes becomes non-uniform, and the reaction rate and the yield decrease. Start over.

The filling length of the catalyst 11 is determined as the difference between the depths of the unfilled space of the reaction tube 12 from the upper tube sheet surface 18 before and after filling. The depth of the non-filled space can be obtained, for example, by inserting a wire or the like and measuring the length of the wire or the like.

When the catalytic gas phase oxidation reaction is industrially performed, the number of reaction tubes in the multi-tube heat exchange type reactor may be 50 or more because the production amount is large. In such a case, the filling length of all the reaction tubes may be measured to calculate the average value, but for the purpose of shortening the working time of the average value calculation, the number of reaction tubes for which the average value is calculated is set. 10 or more and 0.5% to 99.5%, preferably 1% to 60%, more preferably 1.5% to 40%, most preferably 2% to 20% of the total number of reaction tubes. It is preferable that the number is a natural number in the range. In this case, the reaction tube to be the average value is first charged with the catalyst, and after calculating the average value of their filling lengths, the other reaction tubes are filled with the catalyst, and if the filling length is measured, The filling operation can be carried out more easily. Further, the larger the number of reaction tubes to be measured, the more accurate the average value can be obtained. On the other hand, the smaller the number, the shorter the working time.

At this time, it is preferable that the method of extracting the reaction tube from which the average value is to be calculated is random. As a method of randomly extracting, for example, a method of dividing into two or more groups so that the number of reaction tubes is approximately the same and extracting the same number of reaction tubes from each group can be mentioned. According to this method, the reaction tubes can be uniformly extracted, so that the reliability of the average value can be increased. Here, “substantially equal” means a difference in the number of lines within 10% of the total number. If the difference is within 10% of the total number, the error of the average value can be ignored. Further, in order to divide the reaction tube 12 into two or more groups, the tube plate surface 18 is arranged in the direction perpendicular to the length direction of the reaction tube 12 and the end of each reaction tube 12 is attached.
Is divided into two or more areas so that the area of each area is the same, and the reaction tubes attached to each area are grouped together, so that the extraction of the reaction tube becomes simple. Note that, as described above, the number of reaction tubes for which the average value is calculated may be reduced, but the measurement of the filling length is preferably performed in more reaction tubes, and particularly in all reaction tubes. preferable.

The catalyst can be filled in each reaction tube 12 twice or more. If the number of reaction tubes is 50 or more,
The reaction tube for which the average value of the filling length is calculated may be reselected every time, or the same reaction tube may be selected over all times. If the reaction tube is selected again for each time, the accuracy of the average value can be further improved, and if the same reaction tube is selected for all times, it is possible to save the trouble of selecting the reaction tube for each time.

The filling operation is performed twice or more for each reaction tube in the following cases, for example. That is, when the reaction tube 12 is filled with different kinds of catalysts to form a plurality of catalyst layers, or when a mixture of a catalyst and a catalyst diluent or the like is filled with several kinds having different mixing ratios, a plurality of layers are formed. For example, in the case of forming it, or in the case of efficiently carrying out the reaction, the joint between the reaction tube and the upper and lower tube plates of the multi-tube heat exchange reactor is filled with only the carrier or the catalyst diluent. As described above, when the catalyst is charged twice or more, the reaction strength of each reaction tube can be adjusted, and thus the reaction rate and yield of the reaction tube can be made more uniform. Even when the filling work is performed twice or more for each reaction tube, the catalyst is weighed for each filling time (each layer), and the filling length for each layer is further measured to obtain the filling length for each layer of each reaction tube. The difference from the average value of the filling length is set to be ± 20% or less of the average value of the filling length.

The catalyst 11 packed in the reaction tube 12 is not particularly limited as long as it is an oxidation catalyst used for a multi-tube heat exchange type reactor, and for example, a powder catalyst containing a catalyst component is tableted. Examples thereof include those molded into pellets or cylinders by extrusion or the like, those in which alumina, silica, carbon, titania, etc. are molded into spherical shapes or pellets or cylinders, and the catalyst components are supported on the surfaces of the carriers. Examples of the catalyst component include complex oxides such as molybdenum and bismuth. Catalyst 11
The size of is determined in consideration of its effective area, pressure loss in the reactor, etc.
The range is about 20 mm. Examples of the catalyst diluent include a carrier formed by molding alumina, silica, carbon, titania or the like into a spherical shape, a pellet shape or a cylindrical shape, or a ring made of a metal inert to the reaction.

The outer diameter, wall thickness, length, and number of the reaction tubes 12 are not particularly limited, but the outer diameter is usually 7 mm to 60 mm. The wall thickness is usually 1 mm to 4 mm. The length is usually 0.5 m to 10 m. Also, the number is usually 1
It is 0 to 40,000.

A niter is preferably used as a heat medium for heating or removing heat from the reaction tube 12. Here, the niter is a high temperature heat medium containing sodium nitrite, potassium nitrate, sodium nitrate and the like. As shown in FIG. 1, the heat medium is supplied from the heat medium inlet 15 to the shell-and-tube heat exchange reactor 10.
It flows in and flows out to the heat medium outlet 16.

In the synthesis of methacrolein using the multitubular heat exchange reactor 10, since the reaction efficiency is increased,
Reaction pressure 50 kPa to 500 kPa, reaction temperature (heat medium temperature) 200 ° C. to 500 ° C., concentration of isobutylene and / or tertiary butyl alcohol in the raw material gas is 0.5% by mass to 10% by mass, oxygen mole in the raw material gas The ratio is preferably 0.5 to 30 times that of isobutylene and / or tertiary butyl alcohol, and the space time of the raw material gas is preferably about 500 h ^{-1 to} 3000 h ^-1 (NTP).

In the above-described first embodiment, since the mass of the catalyst filled in each reaction tube 12 is within a certain range, the filling amount of the catalyst in contact with the raw material gas is uniform in each reaction tube. . As a result, the catalyst load between the reaction tubes 12 becomes uniform. Further, since the filling length of the catalyst 11 filled in each reaction tube 12 is set within a certain range, it is possible to detect a catalyst filling error due to a bridge or crushing of the catalyst with high accuracy and to make the filling density uniform. . As a result, since the gas flow rate can be made uniform, the contact time of the source gas in each reaction tube 12 can be made uniform. As a result of uniform catalyst load and contact time between each reaction tube 12, each reaction tube 1
The reaction in 2 becomes uniform. Therefore, even in the gas-phase catalytic oxidation reaction for producing methacrolein or methacrylic acid, which has a large reaction heat, side reactions can be controlled and the reaction rate can be improved, so that the productivity can be improved.

The present invention is not limited to the above-described first embodiment, as long as the catalyst mass of each reaction tube is made uniform and the gas flow rate of each reaction tube is made uniform. Hereinafter, a second embodiment will be described in which the catalyst mass of each reaction tube is made uniform and the pressure loss of each reaction tube is made uniform.

Also in the second embodiment, when the catalyst is charged into the reaction tubes 12 of the multi-tube heat exchange reactor shown in FIG. 1, the catalyst load is the same as in the first embodiment. In order to make the temperature uniform, the difference between the amount of catalyst charged in each reaction tube and the control target amount is within ± 10% of the control target amount, preferably within ± 5%. Further, when the catalyst is charged, the pressure loss of each reaction tube 12 is set within a certain range. That is, the ratio (also called the control width) of the difference between the pressure loss of each reaction tube and the average value of the pressure loss with respect to the average value of the pressure loss is within ± 20%, preferably within ± 15% of the average value of the pressure loss. , More preferably within ± 10%, most preferably within ± 5%. When the pressure loss deviates from the control width, the gas flow rate between the reaction tubes becomes uneven, so that the catalyst is charged again in the reaction tube until it falls within the control width. As the catalyst 11, the same catalyst as in the first embodiment can be used.

Here, the pressure loss means that an inert gas such as nitrogen or air is continuously introduced at a constant flow rate from one opening of the reaction tube 12 filled with a catalyst, and the other opening is opened to the atmosphere. It is the pressure on the inflow side when the gas is let out from the section. Although the measurement conditions of the pressure loss is not particularly limited, it is usually gas flow rate 1 m ³ / time through 10m ³ / time order. If the gas flow rate is less than 1 m ³ / hour, the pressure loss may not be measured correctly, and if it exceeds 10 m ³ / hour, the catalyst may be crushed by the pressure.

When the number of reaction tubes is 50 or more,
Similar to the calculation of the average value of the filling length, the number of reaction tubes for which the average value of pressure loss is calculated is 10 or more, and 0.5% to 99.5% of the total number of reaction tubes, preferably 1 % ~ 60
%, More preferably 1.5% to 40%, and most preferably 2% to 20%, which is a natural number. In this case, the reaction tube to be averaged is first charged with the catalyst, and after calculating the average value of those pressure losses, the other reaction tubes are charged with the catalyst, and if the pressure loss is measured, The filling operation can be carried out more easily. The greater the number of reaction tubes to be measured, the more accurate the average value can be obtained. On the other hand, the smaller the number, the shorter the working time. Regarding the method of randomly extracting the reaction tubes that are the target of the average value calculation, similar to the calculation of the average value of the filling length,
A method may be mentioned in which the reaction tubes are divided into two or more groups so that the number of reaction tubes is approximately the same, and the same number of reaction tubes are extracted from each group.
According to this method, the reaction tubes can be extracted without bias,
The reliability of the average value can be increased. Further, to divide into two or more groups, the tube plate surface 1 is arranged in a direction perpendicular to the length direction of the reaction tube 12 and the end of each reaction tube 12 is attached.
If 8 is divided into two or more areas so that the area per area is equal and the reaction tubes attached to each area are regarded as a group, the extraction of the reaction tube becomes simple. As described above, the number of reaction tubes for which the average value is calculated may be reduced, but the pressure loss measurement is preferably performed in more reaction tubes, and particularly in all reaction tubes. preferable.
Also, as in the first embodiment, the catalyst can be filled in each reaction tube 12 twice or more. When the number of reaction tubes is 50 or more, the reaction tube for which the average value of pressure loss is calculated may be reselected for each time, or the same reaction tube may be selected for all times. Good. If the reaction tube is selected again for each time, the accuracy of the average value can be further improved, and if the same reaction tube is selected for all times, it is possible to save the trouble of selecting the reaction tube for each time.

In the above-described second embodiment, since the amount of catalyst filled in each reaction tube 12 is within a certain range, the amount of catalyst contacting the source gas is uniform in each reaction tube. . As a result, the catalyst load between the reaction tubes 12 becomes uniform. Further, since the pressure loss of each reaction tube 12 is within a certain range, it is possible to detect the catalyst filling error due to the bridge or crushing of the catalyst with high accuracy, and to make the filling density uniform. As a result, since the gas flow rate can be made uniform, the contact time of the source gas in each reaction tube 12 can be made uniform. As the catalyst load and contact time between the reaction tubes 12 become uniform, the reaction in each reaction tube 12 becomes uniform. Therefore, even in the gas-phase catalytic oxidation reaction for producing methacrolein or methacrylic acid, which has a large reaction heat,
Since the side reaction can be controlled and the reaction rate can be improved, the productivity can be improved.

In the first embodiment, the packing length of the catalyst is set to a certain range, and in the second embodiment, the pressure loss is set to a certain range. However, in the present invention, these are set as the third embodiment. By combining both the embodiment examples, both the packing length and the pressure loss of the catalyst can be set within a certain range. That is, when the catalyst is filled in each reaction tube, the difference between the amount of the catalyst filled in each reaction tube and the control target amount is set within ± 10% of the control target amount, and the control width of the filling length of each reaction tube is set. Within ± 20%, and control width of pressure loss of each reaction tube within ± 20%. In this case, since the filling length and the pressure loss are within a certain range, the uniformity of the packing density of the catalyst is increased, and the gas flow rate can be made more uniform. As a result, the contact time of the raw material gas in each reaction tube can be made more uniform, and the reaction in each reaction tube 12 can be made more uniform. Therefore, the side reaction can be more controlled, and the reaction rate can be further improved, so that the productivity can be further improved.

When the number of reaction tubes is 50 or more, the reaction tube extracted when calculating the average value of the filling length is the same as the reaction tube extracted when calculating the average value of pressure loss. Good. In this way, the work of newly selecting a reaction tube for pressure loss measurement can be simplified. Also, if either one of the packing length and pressure loss of the catalyst is measured for more reaction tubes, preferably for all reaction tubes,
The number of reaction tubes for the other measurement may be reduced. That is, if either one is measured, the effect of making the packing density uniform is sufficiently exerted, and if the number of reaction tubes is large, it is more satisfactory in the reaction tubes not measuring the other. Even if there is a reaction tube that is not filled to a certain degree, its influence is small, so that the yield and the reaction rate can be improved. Further, as in the first and second embodiments, the catalyst can be filled into each reaction tube 12 twice or more. When the number of reaction tubes is 50 or more, both the catalyst filling length and the pressure loss may be measured for each layer, but either the catalyst filling length or the pressure loss is measured for each layer. Then, for the same reason as described above, the other does not have to be measured for each layer. By doing so, the labor for filling management is significantly reduced.

Although methacrolein was synthesized using isobutylene and / or tertiary butyl alcohol and molecular oxygen as raw materials in the above-mentioned first, second and third embodiments, the present invention is not limited to this. However, there is no limitation as long as it is a reaction in which a fixed bed catalyst is filled in a large number of reaction tubes and a raw material gas is circulated in the reaction tubes. For example, an acrolein synthesis reaction for reacting propylene with molecular oxygen to synthesize acrolein, an acrylic acid synthesis reaction for reacting acrolein with molecular oxygen to synthesize acrylic acid, and a reaction between methacrolein and molecular oxygen. It may be a methacrylic acid synthesis reaction for synthesizing methacrylic acid. At that time, the reaction conditions are preferably appropriately determined according to the reactor specifications, the reaction rate, the reaction time, the performance of the fixed bed catalyst, and the like. Further, in the above-described first embodiment example and second embodiment example, the heat medium and the raw material gas are supplied by the upflow from the lower side to the upper side. It can also be supplied. The effect of the present invention is exhibited even in the downflow.

[0034]

EXAMPLES The present invention will be specifically described below with reference to examples. (Examples 1 to 13 and Comparative Examples 1 to 4) Using a multitubular heat exchange reactor of the same type except that the multitubular heat exchange reactor 10 shown in FIG. Methacrolein was synthesized by vapor-phase catalytic oxidation using molecular oxygen as a raw material. At that time, the reaction pressure was 200 kPa, the reaction temperature (heat medium temperature) was 340 ° C., the isobutylene concentration in the raw material gas was 5 vol%, the oxygen molar ratio in the raw material gas was 2, and the space time of the raw material gas was 980 h ⁻¹ (NTP ). Also,
As the fixed bed catalyst (catalyst 11), a molybdenum-bismuth-based oxidation catalyst molded into a cylindrical shape by extrusion was used. All reaction tubes 12 are made of stainless steel and have an outer diameter of 31.
The one having a thickness of 8 mm, a thickness of 2.3 mm and a length of 5.5 m was used. Each reaction tube 12 was filled with the catalyst 11 from the upper stencil plate 18 in two divided portions to form two catalyst layers. That is,
The first time, 1500 g (control target amount) of a mixture of a cylindrically shaped catalyst and a stainless steel ring that is a catalyst diluent at a mass ratio of 7: 3 was filled, and the first time, and the second time Then, only the catalyst molded in a cylindrical shape was filled with 500 g (control target amount) to form a second layer. The catalyst was weighed for each catalyst layer in each reaction tube so that the difference between the amount of catalyst filled in the reaction tube and the control target amount was within 5% of the control target amount.

Based on the conditions of Table 1, Examples 1 to 13,
A vapor phase catalytic oxidation reaction of isobutylene of Comparative Examples 1 to 4 was performed. Here, "the number of reaction tubes" is the number of reaction tubes of the multi-tube heat exchange reactor, "average value calculation target ratio" is the ratio of the reaction tubes extracted to calculate the average value of the filling length or pressure loss, "Extraction method" is a method of extracting the reaction tube for calculating the average value of the filling length or pressure loss, and "control width" is the filling length or pressure loss of each reaction tube and the average for the average value of the filling length or pressure loss. It is the ratio of the difference from the value. In addition,
When measuring the filling length or pressure loss, all reaction tubes are the measurement targets. Also, in the "extraction method", "the same" means that the same reaction tube is the target for calculating the average value for all layers, and "different" is the target for calculating the average value by extracting the reaction tube for each layer. In other words, “after” means that the values are measured for all reaction tubes after all layers are filled, and then the reaction tubes are extracted and the average value is calculated. Further, when measuring both the filling length and the pressure loss, the reaction tubes for which the average value was calculated were extracted separately. Also, the number of reaction tubes is 5
When the number of reaction tubes exceeds 0, the reaction tubes were extracted by dividing the reaction tube group into four and selecting the same number of reaction tubes from them. However, the difference in the number of reaction tubes in each reaction tube group was set to be within 5% of the total number of reaction tubes. The results of the reaction are shown in Table 1. As a result of the reaction, the reaction rate of isobutylene in the raw material gas, the selectivity of isobutylene to methacrolein, and the yield obtained by multiplying the reaction rate and the selectivity are shown. Here, the reaction rate of isobutylene is the ratio of the number of moles of isobutylene consumed in the oxidation reaction to the number of moles of isobutylene in the raw material gas. The selectivity to methacrolein is the ratio of the number of moles of methacrolein to the number of moles of isobutylene consumed in the oxidation reaction.

[0036]

[Table 1]

In Examples 1 to 13, since the control length of the filling length and / or the pressure loss was within ± 20%, the reaction rate was high and the selectivity was high, and the yield of methacrolein was high. On the other hand, in Comparative Examples 1 to 4, since the control length of the filling length and / or the pressure loss exceeded ± 20%, the reaction rate was low and the selectivity was low, and the yield of methacrolein was low.

(Examples 14 to 16) Reactions were carried out in the same manner as in Examples 1 to 13 except that the catalyst was charged under the conditions shown in Table 2. However, the filling length was measured for all the reaction tubes, but the pressure loss was measured only for the reaction tubes extracted as the target for calculating the average value. In Examples 14 to 16, the reaction rate was high and the selectivity was high, so that the yield of methacrolein was high.

[0039]

[Table 2]

(Examples 17 to 19) The reaction was carried out in the same manner as in Examples 1 to 13 except that the catalyst was charged under the conditions shown in Table 3. However, the pressure loss was measured for all the reaction tubes, but the filling length was measured only for the reaction tubes extracted as the target for calculating the average value. In Examples 17 to 19, the reaction rate was high and the selectivity was high, so that the yield of methacrolein was high.

[0041]

[Table 3]

[0042]

According to the present invention, each reaction tube is filled with the catalyst so that the amount of the catalyst loaded is within a certain range, so that the catalyst load between the reaction tubes becomes uniform. At the same time, since at least one of the filling length and the pressure loss of each reaction tube is set within a certain range, the contact time of the raw material gas becomes uniform. By making the catalyst load and contact time uniform, the reaction between each reaction tube becomes uniform, so even if it is a catalytic gas-phase oxidation reaction with a very large reaction heat, side reactions are suppressed and the reaction rate and yield are reduced. The rate can be increased and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a multi-tube heat exchange reactor of the present invention.

[Explanation of symbols]

10 Multi-tube heat exchange reactor 11 catalyst 12 reaction tubes

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[Procedure amendment]

[Submission date] June 25, 2002 (2002.6.2)
5)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C07C 57/05 C07C 57/05 // C07B 61/00 300 C07B 61/00 300 (72) Inventor Hidezawa Takezawa Hiroshima Prefecture 20-1 Miyukicho, Otake-shi Mitsubishi Rayon Co., Ltd. Otake Works (72) Inventor Toshihiro Sato 20-1 Miyukicho, Otake-shi, Hiroshima Mitsubishi Rayon Co., Ltd. F-term inside Otake Works 4G070 AA01 AB05 BB02 CB07 CB17 CC07 DA22 4H006 AA02 AA04 AC45 AC46 BA13 BA14 BA30 BA82 BE31 BS10 4H039 CA62 CA65 CC30

Claims (12)

[Claims] 1. A catalyst filling method for filling a plurality of reaction tubes of substantially the same shape with a catalyst, wherein the catalyst to be filled in each reaction tube is weighed within ± 10% of a control target amount, and each reaction tube is The difference between the filling length of and the average value of those filling lengths is
A method for filling a catalyst, wherein each reaction tube is filled with the catalyst such that the average filling length is within ± 20%. 2. A catalyst filling method for filling a plurality of reaction tubes of substantially the same shape with a catalyst, wherein the catalyst to be filled in each reaction tube is weighed within ± 10% of a control target amount, and each reaction tube is The method for filling a catalyst is characterized in that each reaction tube is filled with the catalyst such that the difference between the pressure loss and the average value of the pressure loss is within ± 20% of the average value of the pressure loss. 3. In a method of packing a catalyst for packing a catalyst into a large number of reaction tubes of substantially the same shape, the difference between the packing length of each reaction tube and the average value of the packing lengths is
It should be within ± 20% of the average value of the filling length, and the difference between the pressure loss of each reaction tube and the average value of those pressure losses should be within ± 20% of the average value of the pressure loss. A method for filling a catalyst, which comprises filling each reaction tube with a catalyst. 4. When the number of reaction tubes is 50 or more, 1
0 or more and 0.5 to 99.5% of the total number of reaction tubes
The number of reaction tubes consisting of natural numbers in the range is extracted, and a value obtained by averaging the filling lengths of the extracted reaction tubes is set as an average value of the filling lengths. How to fill the catalyst. 5. When the number of reaction tubes is 50 or more, 1
0 or more and 0.5 to 99.5% of the total number of reaction tubes
The number of reaction tubes consisting of natural numbers in the range of is extracted, the value obtained by averaging the filling lengths of these extracted reaction tubes is taken as the average value of the filling length, and the value obtained by averaging the pressure loss of all the reaction tubes, The catalyst filling method according to claim 3, wherein the average value of the pressure loss is used. 6. When the number of reaction tubes is 50 or more, 1
0 or more and 0.5 to 99.5% of the total number of reaction tubes
The number of reaction tubes consisting of natural numbers in the range is extracted, and a value obtained by averaging the pressure loss of the extracted reaction tubes is set as the average value of the pressure loss.
The method for filling a catalyst according to item 1. 7. The catalyst according to claim 4, wherein the reaction tubes are divided into two or more groups so that the number of reaction tubes is substantially the same, and the same number of reaction tubes are extracted from each group. Filling method. 8. The catalyst packing method according to claim 1, wherein the catalyst is packed in each reaction tube twice or more. 9. The catalyst packing method according to claim 8, wherein the packing length and / or pressure loss of the catalyst in the same reaction tube is measured for each packing. 10. A multi-tube heat exchange reactor characterized in that the reaction tube is filled with the catalyst by the method for filling the catalyst according to any one of claims 1 to 9. 11. An acrolein synthesis reaction for reacting propylene with molecular oxygen to synthesize acrolein and / or an acrylic acid synthesis reaction for reacting acrolein with molecular oxygen to synthesize acrylic acid. The multitubular heat exchange reactor according to claim 10. 12. A methacrolein synthesis reaction in which isobutylene or tert-butyl alcohol is reacted with molecular oxygen to synthesize methacrolein and / or a methacrylic acid in which methacrolein is reacted with molecular oxygen to synthesize methacrylic acid. The multi-tube heat exchange reactor according to claim 10, wherein a multi-tubular heat exchange reactor is performed.