JP2003523986A - Method for adjusting raw material concentration in gas phase contact reaction process, method for controlling reaction process by the method, and method for producing lower fatty acid or lower fatty acid ester using the control method - Google Patents

Abstract

(57) [Summary] In the adjustment of the raw material concentration in the gas supplied to the reactor in the gas phase catalytic reaction process having a recycling system, the raw material concentration in the gas of the process is measured, and the measured value is used to control the process. A method for adjusting the concentration of a raw material including controlling the concentration of a raw material in a gas supplied to a reactor as a result of determining and supplying a supply amount of a newly added raw material, and a method of controlling a reaction process by the adjusting method.

Description

Detailed Description of the Invention

Description of Related Application This application is filed on December 21, 2000 in accordance with US Code 35, section 111 (b).
US Code 3 on the filing date of US Provisional Application No. 60 / 256,914 filed
No. 5, 119 (e) (1), an application pursuant to US Code 35, section 111 (a), claiming benefit. TECHNICAL FIELD The present invention relates to a method for adjusting a raw material concentration in a gas phase catalytic reaction process, a method for controlling the reaction process by the adjusting method, and a method for producing a lower fatty acid or a lower fatty acid ester using the method.

More specifically, a gas phase having a so-called recycle system in which a new raw material is additionally supplied to a gas containing an unreacted raw material after passing through a reactor for carrying out a gas phase catalytic reaction and the gas is returned to the reactor again. In the catalytic reaction process, a method for determining the feed amount of a new raw material on the basis of the raw material concentration in the gas measured at any place in the process, and consequently adjusting the raw material concentration in the gas to be supplied to the reactor, And a method for stably controlling the reaction process itself by the adjusting method, and a method for producing a lower fatty acid or a lower fatty acid ester using the controlling method. (Background Art) In a process using a reactor that performs a gas-phase catalytic reaction type reaction, a gas supplied to the reactor passes through the reactor only once, and all raw materials in the gas react to obtain a target substance. There is no possible case. In particular, when two or more raw materials are used, the theory that the reaction requires one or more raw materials for the purpose of improving the reaction results such as the conversion rate of the raw materials in the reaction or the selectivity to the target substance or stabilizing the reaction. It may be used in excess of the amount. In such a case, it is usually essential from the economical aspect of the process to collect and reuse the excessively used raw material.

Therefore, a process using a reactor for carrying out a reaction of a gas phase catalytic reaction is such that a target substance is separated (after purification if necessary) after a gas containing a raw material passes through the reactor.
It is common to have a so-called recycle system in which a new raw material is additionally supplied to a gas containing unreacted raw material to adjust the concentration of the raw material in the gas and then this gas is returned to the reactor for reaction. is there.

In order to control in such a reaction process, that is, to maintain the reaction results or stabilize the reaction, it is necessary to control so-called “process operating conditions” such as various reaction conditions. Above all, it is important to control the concentration and composition ratio of the raw materials in the gas supplied to the reactor, and the pressure in the system, particularly in the reactor.

Generally, in the process of gas-phase catalytic reaction, the presence of so-called “inert substances” unrelated to the reaction cannot be ignored.

[0006]   Generally for inert materials   1) Unwanted substances by-produced in the reaction   2) Substances contained in the raw material itself as impurities   3) Inert gas added for the purpose of controlling the concentration of raw materials for controlling the reaction Etc. are considered to be included.

These unintended substances, impurities, and inert gases accumulate in the system by repeating the recycling operation in the reaction process having the above-mentioned recycling system,
From the viewpoint of the reaction, it becomes a factor of relatively lowering the concentration of the raw materials and raising the pressure in the system.

Therefore, in a reaction process having a recycle system, one of the purposes is to discharge the inert substances to the outside of the system to suppress an increase in the pressure inside the system, and to release part of the gas inside the system to the outside of the system. A so-called "purge operation" is performed.

Another purpose of the purging operation in the reaction process having a recycle system is to control the supply amount of the raw material consumed in the reaction when the raw material is newly added, and thus to control the feed amount of the raw material in the gas supplied to the reactor. One way to do this is to adjust the concentration and consequently control the reaction process itself.

There are very many examples of such a process in which the pressure increase in the system is suppressed by the purging operation and the raw material concentration is adjusted at the same time. Among them, “Basics and Applications of Instrumentation Systems (by Shigemoto Senbon and Taita Hanabuchi) Ohmsha Co., Ltd. October 20, 1993, 1st edition, 9th edition
As a specific example thereof, "printing issue", pages 530 to 531, "Chapter 9 Process Unit Control (Application I), Item 6 (e) Recycle Reaction System Control" can be mentioned.

According to the review article of this publication, in a process having a recycle system, the amount of gas released in the purging operation (hereinafter, referred to as “purge amount”) keeps the concentration of inert substances in the system constant. As described above, the value is determined by the value of the concentration controller, or the pressure increase in the system is interpreted as an increase in inert substances, and the pressure controller is used instead of the above-mentioned concentration controller, and it is determined by the value. Has been done.

In the former case, when the concentration controller detects that the concentration of the inert substance in the gas has risen, the purge amount is increased. Then, the discharge of the inert material is promoted and the concentration of the inert material in the system gradually decreases. At the same time, since the increase in the purge amount is also an operation in the direction of decreasing the pressure in the system, new raw material is additionally supplied into the system, resulting in an increase in the concentration of the raw material in the gas.

In the latter case, when the pressure regulator detects an increase in pressure, the purge amount is increased to reduce the pressure and increase the discharge of inert substances. At the same time, a new raw material is additionally supplied into the system to compensate for the pressure drop due to this, and the concentration of the raw material in the gas rises as in the former case.

In any case, by controlling the purge amount, the concentration of the inert substance in the system is controlled, in other words, the concentration of the raw material of the gas supplied to the reactor is adjusted, and at the same time, the pressure in the system is adjusted. As a result, it is a method of controlling the reaction.

In such a method, when the amount of the inert material produced or carried in the system and the amount of the inert material discharged to the outside of the system by the purging operation have reached equilibrium, the concentration of the raw material in the gas and the internal content of the system Any of the pressures will equilibrate to a point, resulting in a steady state and stable reaction and the entire process.

Further, in this method, since the supply amount of the new raw material to be additionally supplied is automatically adjusted depending on the pressure in the system, it is possible to omit a means such as a control valve for adjusting the raw material supply amount. It has the advantage of being possible. In the example process described in the above review,
No adjusting means such as the adjusting valve is used.

In such a process that uses a reactor that performs a gas phase catalytic reaction type reaction and has a recycling system, a purge operation is used to adjust the raw material concentration of the gas to be supplied to the reactor, and it depends on the raw material concentration. It is very common to control the reaction in a stable and successful manner.

However, depending on the characteristics of the catalyst used in the reaction, this method may not provide sufficient control. A specific example thereof is, for example, the case of a process using a catalyst in which the range of raw material concentration required for controlling the reaction stably and with good performance is extremely narrow.

In a process using a catalyst having such characteristics, in order to appropriately control the reaction, the concentration of the raw material in the gas supplied to the reactor is adjusted accurately so that it falls within a required narrow range. It is necessary. However, the conventional method described above,
That is, the following inconveniences can be considered in the control of the reaction by the method of adjusting the raw material concentration by the purge amount.

First, when a change occurs in the concentration of the inert material or the concentration of the raw material, it means that the control of the reaction has already deviated from the proper value and further deviating from the characteristics of the catalyst, and it is immediately returned to the proper value. There is a need. For this purpose, it is necessary to change the raw material concentration so as to sufficiently cancel the detected change, but it is difficult to set the purge amount to realize it. In addition, the relationship between the change in the raw material concentration and the setting of the purge amount varies unevenly as the deterioration of the catalyst progresses, the load of the process changes, and the like, so that it is necessary to adjust it frequently, which is not realistic.

Further, in the method of controlling the additional supply amount of the raw material in a form of operating the purge amount and compensating for the pressure drop due to it, the purge flow rate operation, the system internal pressure change, the additional raw material supply amount change, and the raw material concentration change are brought about. In the process, a time delay is likely to occur, and accurate control is difficult.

In addition, since the purge amount itself is usually smaller than the hold amount in the system, and the change amount of the purge amount operated for the purpose of adjusting the raw material concentration is smaller, the influence of the purge operation on the pressure is affected. Is unavoidable. As a result, the change in the pressure in the system due to the purging operation is small and gradual. It is very difficult to accurately detect this slight change in pressure and set an additional supply amount of a new raw material for setting the raw material concentration to a desired value and reflecting it in the process.

As described above, in a reaction process that uses a gas-phase catalytic reaction type reaction and has a recycle system, the raw material concentration in the reactor can be adjusted by adjusting the purge amount as is generally done in the past. An example of a process in which optimum control is difficult is shown by the method of adjusting the pressure and adjusting the pressure in the system. Of course, as an application example of the present invention, the properties of the catalyst are not limited to this example. DISCLOSURE OF THE INVENTION The inventors of the present invention use a reactor that performs a reaction of a gas phase catalytic reaction type, and in a reaction process having a recycle system, control the purge amount to supply the amount of raw material additionally supplied to the reactor. To control the raw material concentration at the same time as the raw material concentration, and thus to control the reaction process.The raw material concentration is adjusted in a process that uses a catalyst that is difficult to control by conventional methods. The present invention has been completed by conducting various studies on the method and the control method of the reaction process.

That is, in the present invention (I), in the adjustment of the raw material concentration in the gas supplied to the reactor in the gas phase catalytic reaction process having a recycle system, the raw material concentration in the gas of the process is measured, and the measurement is performed. It is a method of adjusting the raw material concentration, which includes determining the supply amount of the raw material to be newly added to the process according to the value, and then controlling the raw material concentration in the gas supplied to the reactor.

Further, the present invention (II) is a method for controlling a reaction process, wherein at least one of the control methods in the control of the gas phase catalytic reaction process is the method for adjusting the raw material concentration according to the present invention (I).

Furthermore, the present invention (III) is a method for producing a lower fatty acid from a lower olefin and oxygen in the presence of a catalyst, which is controlled by the process control method of the present invention (II).

Furthermore, the present invention (IV) produces a lower aliphatic carboxylic acid ester from a lower olefin and a lower fatty acid in the presence of a catalyst, which is controlled by the process control method of the present invention (II). Is the way.

Furthermore, the present invention (V) is a method for producing a lower fatty acid ester from a lower olefin, oxygen and a lower fatty acid in the presence of a catalyst, which is controlled by the process control method of the present invention (II). Is.

[0029]   BEST MODE FOR CARRYING OUT THE INVENTION   Hereinafter, the present invention will be described in detail.

In the present invention (I), in the adjustment of the raw material concentration in the gas supplied to the reactor in the gas phase catalytic reaction process having a recycling system, the raw material concentration in the gas of the process is measured, and the measured value is measured. According to the method, the raw material concentration is adjusted by determining the supply amount of the raw material newly added to the process and controlling the raw material concentration in the gas supplied to the reactor as a result.

According to the method for adjusting the concentration of the raw material in the gas supplied to the reactor in the gas-phase catalytic reaction process of the present invention (I), the gas in the gas supplied to the reactor in the gas-phase catalytic reaction process having a recycle system The raw material concentration is not adjusted by the conventional indirect method of replenishment for maintaining the pressure against the pressure drop in the system by the purge operation, but the raw material concentration is measured at any place in the process, It is adjusted by the direct method of determining and supplying a newly added amount based on the measured value.

The present invention (I) can be applied without particular limitation to a process by any reaction as long as it is a gas phase catalytic reaction process having a recycling system. Due to various causes, not only in the case of reactions where it is difficult to adjust the appropriate raw material concentration by the conventional purging method, but also in the case of purging operations where there is no practical problem, it can be applied for the purpose of more efficient reaction control. It doesn't matter. Examples of particularly preferable applications include a method for producing a lower fatty acid from a lower olefin and oxygen in the presence of a catalyst, a method for producing a lower fatty acid ester from a lower olefin and a lower fatty acid in the presence of a catalyst, and the like. You can

The reactor for the gas phase catalytic reaction of the present invention (I) is not particularly limited. The reaction is preferably a fixed bed gas phase catalytic reaction, and more preferably the reactor may have a multi-tube type and / or a multi-layer type. In general, a tubular type and / or multilayer type reactor is superior in terms of reaction results, thermal efficiency, controllability, and the like. Of course, the shape of the reactor is not limited to this.

In the present invention (I), there is no particular limitation on the place where the concentration of the raw material in the gas is measured, and it can be performed at any place in the process. FIG. 1 is shown as an example of a conceptual diagram of the process. Each characteristic line in this example, that is, (A) a line immediately before the reactor in which a new raw material is added to recycled gas (B) a separation device from the reactor outlet (C) outlet line from separator (D) purge line (E) recycle gas line before new raw material is added, etc.

The locations where the raw material concentration is measured are preferably (A) and (D). (A) is preferable in that the raw material concentration also includes the raw material newly added immediately before the reactor and that the factor that causes disturbance to the raw material concentration is the smallest. (
The method (D) is preferable in that the entire amount of the measured gas can be introduced to the purge line as it is, and therefore it can be used even in a measuring method that may affect the raw material concentration itself. However, even if measurement is performed at any of (A) to (E), the value of the amount of newly supplied raw material can be calculated from the value of the raw material concentration at that position. You are not limited to these places.

There is no particular limitation on the method for measuring the raw material concentration. A commonly used method for measuring the concentration of gas components can be used. Specifically, for example, a sampling valve is installed at the concentration measurement location, a part of the gas is introduced into gas chromatography, and the composition ratio is measured by combining an appropriate column and a detector, or a cell is installed in the line itself. And a method of spectroscopically measuring the concentration at a specific wavelength can be given, but the present invention is not limited thereto. As preferable conditions for the measuring method, it is possible to accurately measure the concentration in a short time due to the properties of the raw material to be measured, and to be free from the influence of other components mixed.

There is no particular limitation on the method of adjusting the amount of raw material additionally supplied to the process. This can be done by a general method of adjusting the raw material supply amount that has been conventionally performed. Specifically, it can be performed by adjusting means provided in the raw material supply line, for example, a flow rate adjusting valve or the like.

For controlling the amount of the raw material to be additionally supplied according to the measured raw material concentration, a commonly used control method can be used. Specifically, for example, the value of the raw material concentration measured by the method as described above is converted into an electric signal of a certain kind, and the change of the signal controls the adjusting means provided in the raw material supply line to additionally supply the raw material. A method of determining the amount of is possible.

As a more specific method, it is possible to compare the target raw material concentration with the raw material concentration measured at the reactor inlet, and automatically operate the raw material supply amount so as to eliminate this deviation. For example, as such an automatic operation device, a feedback control device (hereinafter, referred to as "PID controller") having proportional, integral, and derivative operations can be used. In this case, a PID controller is used as the concentration controller, and
The raw material concentration in the gas is input as ss Variable (hereinafter, referred to as “PV”), and its operation output (Mmanipulate Variable (hereinafter, referred to as “PV”) is input.
A method of directly operating the raw material supply control valve by "MV") is conceivable.

Furthermore, as a means for locally limiting the disturbance that may occur in the raw material supply amount, the raw material supply amount control valve is also equipped with a PID controller, and the MV of the concentration controller is set to the target value of the raw material supply amount controller. Even better results can be obtained by configuring so-called concentration-flow rate cascade control, which is (Setpoint Value (hereinafter referred to as “SV”)).

Of course, a method of separately calculating a desired raw material concentration based on the mass balance and adjusting the raw material supply amount is also conceivable, and a so-called advanced control method represented by model predictive control or fuzzy control may be used. Generally, it is convenient and easy to use a PID controller.

Next, the present invention (II) will be described. The present invention (II) is a method for controlling a gas phase catalytic reaction process, wherein at least one of the control methods is a method for adjusting the raw material concentration according to the present invention (I).

The present invention (II) is a reaction process that includes the method for adjusting the raw material concentration shown in the present invention (I) as a specific method for stably controlling a general gas phase catalytic reaction process. Is a control method. In other words, the present invention (II) is a method for stably and efficiently controlling the entire process by using the raw material concentration adjusting method shown in the present invention (I) as a means.

In general, control of so-called “process operating conditions” such as various reaction conditions is necessary for control in the reaction process, that is, for maintaining reaction results, stabilizing reaction, and the like. Above all, the concentration of the raw material in the gas usually supplied to the reactor is particularly important for maintaining the reaction results. The present invention (II) has been conventionally performed by adjusting the raw material concentration essential for stable control of the process, that is, replenishment for maintaining the pressure against the pressure drop in the system by the purging operation shown in the present invention (I). Gas-phase catalytic reaction process, which is carried out not by indirect method but by direct method of measuring raw material concentration at any place in the process and determining and supplying new amount based on the measured value. Is a method of controlling the process by adjusting the concentration of the raw material in the gas supplied to the reactor.

Regarding the reaction process to which the present invention (II) can be applied, the measuring place and measuring method of the raw material concentration, and the controlling method of the supply amount of the raw material newly added by the measured value, the present invention (
Similar to I).

The process control method of the present invention (II) may include operating conditions of other processes as long as the effect of the raw material concentration adjusting method of the present invention (I) is not lost. Absent. Specifically, the temperature of the reactor, the flow rate of the gas containing the raw material, and the operating conditions of the separation device (see FIG. 1), which is thought to affect the recycling system, can be mentioned, but the present invention is not limited thereto. Not necessarily. The raw material concentration adjusting method according to the present invention (I) may be included as one of the process controlling methods.

Next, the present invention (III) will be described. The present invention (III) is a method for producing a lower fatty acid from a lower olefin and oxygen in the presence of a catalyst, which is controlled by the method for controlling the process of the present invention (II).

According to the method for producing a lower fatty acid of the present invention (III), in the process of producing a lower fatty acid from a lower olefin and oxygen in the presence of a catalyst, in order to perform efficient and stable control of the process, One of the control methods includes the process control method of the present invention (II). Therefore, the method for producing a lower fatty acid of the present invention (III) is
Needless to say, it depends on the method of adjusting the raw material concentration according to ()), and the measuring place and measuring method of the raw material concentration, and the method of controlling the supply amount of the raw material newly added by the measured value are the same as in the present invention (I).

There is no particular limitation on the catalyst that can be used in the method for producing a lower fatty acid of the present invention (III). Any catalyst can be used as long as it has the ability to oxidize a lower olefin with oxygen to form a lower aliphatic carboxylic acid. Examples of the catalyst include a catalyst containing palladium and a phosphoric acid- or sulfur-containing modifier (JP-A-47-13).
221, JP-A-51-29425), a catalyst containing a palladium salt of a certain heteropolyacid (JP-A-54-57488), and a catalyst comprising a group 3 oxygen compound (JP-A-46). No. 6763).

A catalyst containing a metal palladium-heteropolyacid and / or a salt thereof is preferable, and specific examples thereof include the catalysts disclosed in JP-A-7-89896 and JP-A-9-67298. it can. Of course, it is not limited to these.

The catalyst may be not only a product obtained by tableting the catalyst component itself, but also a supported catalyst supported on a carrier. In the case of a supported catalyst, the carrier that can be used is not particularly limited, and a porous substance that can be usually used as a carrier can be used. Specific examples include silica, diatomaceous earth, montmorillonite, titania, activated carbon, alumina, and silica-alumina, but are not limited thereto.

The shape of the substance that can be used as the carrier of the catalyst of the present invention (III) is not particularly limited, and specifically, powder, spherical, pellet-shaped or any other shape can be used. .

The carrier is more preferably a siliceous carrier whose main component is spherical or pellet-shaped. More preferably, the carrier is silica having a purity of 95% by mass or more based on the total mass of the carrier.

The average particle diameter thereof is preferably in the range of 2 to 10 mm in the case of a fixed bed, and in the range of powder to 5 mm in the case of a fluidized bed.

The reaction temperature in the method for producing a lower fatty acid of the present invention (III) is not particularly limited. The optimum value varies depending on the type of olefin used as the raw material and the catalyst used. Generally, it is preferably 100 to 300 ° C, more preferably 120 to 250 ° C.

The reaction pressure is also not particularly limited. As with the reaction temperature, the type of raw olefin,
Needless to say, the optimum value varies depending on the catalyst used. Generally, it is practically advantageous from the viewpoint of equipment that the pressure is 0.0 to 3.0 MPa (gauge pressure), but the invention is not limited to this. More preferably, it is in the range of 0.1 to 1.5 MPa (gauge pressure).

As the raw material in the method for producing a lower fatty acid of the present invention (III), a lower olefin and oxygen can be mentioned.

The lower olefin is not particularly limited. One or more olefins having 6 or less carbon atoms and having a linear or branched structure having at least one unsaturated bond are preferable. More preferably, ethylene, propylene, 1-butene, 2-butene, butadiene and / or a mixture thereof can be exemplified, but the invention is not limited thereto. More preferably, it is ethylene.

Other compounds, for example, lower saturated hydrocarbons such as methane, ethane and propane may be mixed in such a range that the reaction is not affected.

There is no particular limitation on oxygen. Not only high-purity oxygen but also those diluted with an inert gas such as nitrogen or carbon dioxide, for example, in the form of air can be supplied. Generally, it is advantageous to use oxygen with a high concentration, preferably 99% or higher purity.

There is no particular limitation on the values of the raw material concentrations of the lower olefin and oxygen in the gas. Needless to say, the optimum value varies depending on the type of olefin as the raw material, the catalyst used, etc., as well as the reaction temperature and pressure. Generally, the lower olefin is in an amount of 5 to 80% by volume, preferably 8 to 50% by volume, and the oxygen is in an amount of 1 to 15% by volume, preferably 3 to 10% by volume, based on the total amount of gas. It is supplied to the reaction system in an amount, more preferably in an amount of 4 to 8% by volume.

The space velocity of gas (hereinafter, referred to as “GHSV”) is not particularly limited. Generally, it is preferable to pass the catalyst at 10 to 10000 hr ^-1 , particularly 300 to 5000 hr ^-1 , in the standard state, but it is not limited thereto.

Particularly in the case of a reaction system using a catalyst containing metallic palladium and a heteropoly acid and / or a salt thereof, the presence of water in the reaction system improves the production activity of the lower aliphatic carboxylic acid and the selectivity. It is extremely effective in maintaining the activity of the catalyst. The water vapor is preferably contained in the reaction gas in an amount of 1 to 50% by volume, preferably 5 to 40% by volume.

Next, the present invention (IV) will be described. The present invention (IV) is a method for producing a lower fatty acid ester from a lower olefin and a lower fatty acid in the presence of a catalyst, which is controlled by the method for controlling the process of the present invention (II).

According to the method for producing a lower fatty acid ester of the present invention (IV), in the process for producing a lower fatty acid ester from a lower olefin and a lower fatty acid in the presence of a catalyst, the process is efficiently and stably controlled. Therefore, the process control method of the present invention (II) is included as one of the control methods. Therefore, needless to say, the method for producing a lower fatty acid ester of the present invention (IV) is based on the method for adjusting the raw material concentration according to the present invention (I), and the measurement location and measuring method of the raw material concentration, and a new addition are made depending on the measured value. The method of controlling the supply amount of the raw material is the same as in the present invention (I).

There is no particular limitation on the catalyst that can be used in the method for producing a lower fatty acid ester of the present invention (IV). It is generally well known that it is possible to obtain a corresponding lower fatty acid ester by reacting a lower olefin with a lower fatty acid in the presence of an acidic catalyst. It is also known that a heteropoly acid and / or a salt thereof works effectively as a catalyst for this reaction. Specific examples of these include, for example, JP-A-4-139148, JP-A-4-139149, JP-A-5-65248, and JP-A-5-248.
No. 163200, JP-A-5-170699, and JP-A-5-255185.
The catalysts disclosed in JP-A-5-294894, JP-A-6-72951, JP-A-9-118647 and the like can be mentioned. Of course, it is not limited to these.

The catalyst may be not only the catalyst component itself tableted but also a supported catalyst supported on a carrier. In the case of a supported catalyst, the carrier that can be used is not particularly limited, and a porous substance that can be usually used as a carrier can be used. Specific examples thereof include silica, diatomaceous earth, montmorillonite, titania, activated carbon, alumina and silica-alumina, but are not limited thereto.

The shape of the substance that can be used as the carrier of the catalyst of the present invention (IV) is not particularly limited, and specifically, powder, spherical, pellet, or any other shape can be used. .

The carrier is preferably a siliceous carrier whose main component is spherical or pellet-shaped. More preferably, the carrier is 95% by mass relative to the total mass of the carrier.
Examples thereof include silica having the above purities.

The average particle size thereof is preferably in the range of 2 to 10 mm in the case of a fixed bed, and in the range of powder to 5 mm in the case of a fluidized bed.

The reaction temperature and the reaction pressure in the method for producing a lower fatty acid ester of the present invention (IV) need to be in the range in which the lower fatty acid used as a raw material is kept in a gaseous state, but it is not particularly limited. . Therefore, it goes without saying that it depends on the lower aliphatic carboxylic acid used as the raw material. Generally, the reaction temperature is 100 to 3
The range of 00 ° C is preferable, and the range of 120 to 250 ° C is more preferable.

Although the reaction pressure has a relationship with the reaction temperature, it is generally 0.
A range of 0 to 3.0 MPa (gauge pressure) is practically advantageous and preferred, and a range of 0.1 to 1.5 MPa (gauge pressure) is more preferable, but the range is not limited thereto. Absent.

Examples of raw materials in the method for producing a lower fatty acid ester of the present invention (IV) include lower olefins and lower fatty acids.

The lower olefin is not particularly limited. One or more olefins having 6 or less carbon atoms and having a linear or branched structure having at least one unsaturated bond are preferable, and more preferably ethylene, propylene, 1-butene, 2-butene, butadiene and / or Alternatively, a mixture thereof can be illustrated, but the invention is not limited thereto. More preferably, it is ethylene.

Other compounds, for example, lower saturated hydrocarbons such as methane, ethane and propane may be mixed in such a range that does not affect the reaction.

The lower fatty acid is not particularly limited. Carboxylic acids having 4 or less carbon atoms are preferable, but not limited thereto. Specific examples include formic acid, acetic acid, propionic acid, acrylic acid, methacrylic acid and the like. In particular, acetic acid and acrylic acid are preferable.

As the ratio of the lower olefin and the lower fatty acid to be used, it is desirable to use the lower olefin in an equimolar amount or an excessive molar amount with respect to the lower fatty acid. As for the ratio, the molar ratio of lower olefin: lower fatty acid is preferably in the range of 1: 1 to 30: 1, and more preferably in the range of 10: 1 to 20: 1.

The gas GHSV is not particularly limited. Generally, 10 to 10 in the standard state
000Hr ^-1, particularly preferably passed through the catalyst at 300~5000Hr ^-1, but are not limited thereto.

Particularly in the case of a reaction system using a catalyst composed of a heteropolyacid and / or a salt thereof, it is preferable to allow a small amount of water to exist in the reaction system from the viewpoint of catalyst life. However, if too much water is added, by-products such as ethanol and diethyl ether will increase, which is not preferable. Generally, 1 to 1 in the total amount of lower olefins and lower fatty acids used
It is preferable to select from the range of 15 mol%, more preferably 3 to 8 mol%.

Next, the present invention (V) will be described. The present invention (V) is a method for producing a lower fatty acid ester from a lower olefin, oxygen and a lower fatty acid in the presence of a catalyst, which is controlled by the method for controlling the process of the present invention (II).

According to the method for producing a lower fatty acid ester of the present invention (V), in the process for producing a lower fatty acid ester from a lower olefin, oxygen and a lower fatty acid in the presence of a catalyst, efficient and stable control of the process can be achieved. In order to carry out, the method of controlling the process of the present invention (II) is included as one of the control methods. Therefore, it goes without saying that the method for producing a lower fatty acid ester of the present invention (V) is based on the method for adjusting the raw material concentration according to the present invention (I), and a new place is added depending on the measurement place and measurement method of the raw material concentration and the measured value. The method of controlling the supply amount of the raw material is the same as in the present invention (I).

There is no particular limitation on the catalyst that can be used in the method for producing a lower fatty acid ester of the present invention (V). Any catalyst can be used as long as it has the ability to form a lower fatty acid ester from a lower olefin, a lower fatty acid and oxygen. Examples of the catalyst include palladium as a main component and an alkali metal or alkaline earth metal and at least one metal such as gold, copper, molybdenum, cadmium, lead, vanadium, bismuth, chromium, tungsten, manganese, and iron as a cocatalyst. Examples of such catalyst components include those in which these catalyst components are usually supported on alumina, silica, activated carbon, pumice titanium oxide and the like. Specific examples thereof include JP-A-2-91045, JP-A-5-186393, JP-A-6-47281 and JP-A-7
-136515, JP-A-7-308576, and JP-A-8-38899.
Examples thereof include catalysts disclosed in Japanese Patent Publication No. Of course, it is not limited to these.

The catalyst may be not only the one obtained by tableting the catalyst component itself, but also a supported catalyst supported on a carrier. In the case of a supported catalyst, the carrier that can be used is not particularly limited, and a porous substance that can be usually used as a carrier can be used. Specific examples thereof include silica, diatomaceous earth, montmorillonite, titania, activated carbon, alumina and silica-alumina, but are not limited thereto.

The shape of the substance that can be used as the carrier of the catalyst of the present invention (V) is not particularly limited, and specifically, a powder, a sphere, a pellet, or any other shape can be used. .

The carrier is more preferably a siliceous carrier whose main component is spherical and has a pellet form. More preferably, the carrier is silica having a purity of 90% by mass or more based on the total mass of the carrier.

The average particle size thereof is preferably in the range of 2 to 10 mm in the case of a fixed bed, and in the range of powder to 5 mm in the case of a fluidized bed.

The reaction temperature in the method for producing a lower fatty acid ester of the present invention (V) is not particularly limited. The optimum value varies depending on the type of olefin as a raw material, the catalyst used, and the like, and there is no particular limitation as long as the lower fatty acid as a raw material is in a gaseous state. Generally, it is preferably 100 to 300 ° C, more preferably 120 to 250 ° C.

The reaction pressure is not particularly limited either. As with the reaction temperature, the type of raw olefin,
Needless to say, the optimum value varies depending on the catalyst used. Generally, it is practically advantageous from the viewpoint of equipment that the pressure is 0.0 to 3.0 MPa (gauge pressure), but the invention is not limited to this. More preferably, it is in the range of 0.1 to 1.5 MPa (gauge pressure).

Examples of the raw material in the method for producing a lower fatty acid ester of the present invention (V) include lower olefin, lower fatty acid and oxygen.

The lower olefin is not particularly limited. One or more olefins having 6 or less carbon atoms and having a linear or branched structure having at least one unsaturated bond are preferable, and more preferably ethylene, propylene, 1-butene, 2-butene, butadiene and Examples thereof may include, but are not limited to, and / or mixtures thereof. More preferably, it is ethylene or propylene.

Other compounds, for example, lower saturated hydrocarbons such as methane, ethane and propane may be mixed in such a range that the reaction is not affected.

The lower fatty acid is not particularly limited. A carboxylic acid having 4 or less carbon atoms is preferable, but not limited to this. Specific examples include formic acid, acetic acid, propionic acid, acrylic acid, methacrylic acid and the like. In particular, acetic acid or acrylic acid is preferable.

There is no particular limitation on oxygen. Not only high-purity oxygen but also those diluted with an inert gas such as nitrogen or carbon dioxide, for example, in the form of air can be supplied. Generally, it is advantageous to use oxygen with a high concentration, preferably 99% or higher purity.

There are no particular restrictions on the values of the raw material concentrations of the lower olefin and oxygen in the gas. Needless to say, the optimum value varies depending on the type of olefin as the raw material, the catalyst used, etc., as well as the reaction temperature and pressure. Generally, the lower olefin is in an amount of 5 to 80% by volume, preferably 8 to 60% by volume, and the oxygen is in an amount of 1 to 15% by volume, preferably 3 to 10% by volume, based on the total amount of gas. The amount is most preferably supplied to the reaction system in a ratio of 4 to 8% by volume.

As a specific example of the method for producing a lower fatty acid ester of the present invention (V), in the case of an allyl acetate production method using acetic acid as a lower fatty acid and propylene as a lower olefin, propylene is 40 to 60 volumes. % Is preferable. Further, in the case of a method for producing vinyl acetate using acetic acid as the lower fatty acid and ethylene as the lower olefin, ethylene is preferably supplied in an amount of 20 to 40% by volume.

As a ratio of the lower olefin and the lower fatty acid to be used, it is desirable to use the lower olefin in an equimolar amount or an excessive molar amount with respect to the lower fatty acid. The molar ratio of lower olefin: lower fatty acid is preferably 1: 1 to 30: 1, more preferably 2: 1 to 10: 1.

Further, the gas GHSV is not particularly limited. Generally, in standard conditions, 1
It is preferable to pass the catalyst at 0 to 10000 Hr ^-1 , particularly 300 to 5000 Hr ^-1 ,
It is not limited to this.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but these Examples show the outline of the present invention, and the present invention is not limited to these Examples. .

The present invention will be described using a reaction process of obtaining acetic acid from ethylene and oxygen in the presence of a heteropolyacid-based catalyst for acetic acid production.

Outline of Reaction In the reaction process shown in FIG. 2, ethylene and oxygen are supplied to a reactor as raw materials, acetic acid is separated through a gas-liquid separator, and a gas containing an inert substance and unreacted raw materials is again supplied to the reactor. A recycling system leading to is constructed. Acetic acid is produced as a main product, and carbon dioxide gas, acetaldehyde, ethanol, methyl acetate, propionic acid, etc. are produced as other by-products.

As the target of the conditions in the reactor, the reaction peak temperature of the catalyst bed was 200 ° C., the reaction pressure was 0.75 MPa (gauge pressure), and GHSV1800 Hr ⁻¹ .

Catalyst Preparation Method The catalyst for acetic acid production used in Examples 1 and 2 and Comparative Examples 1 and 2 will be described.

2.81 g of sodium tetrachloropalladate, 1.05 g of chloroauric acid, and 0.1402 g of zinc chloride were weighed, and pure water was added thereto to dissolve them to 45 ml,
An aqueous solution (1) was prepared. Silica carrier (KA-1 carrier manufactured by Sud Chemie, 5 mmφ)
) 69.6 g was added to the beaker in which the aqueous solution (1) was prepared, and the entire amount of the aqueous solution (1) was absorbed by the silica carrier.

Into another beaker, weigh 8.00 g of sodium metasilicate and add 10 parts of pure water to it.
0 g was added and dissolved to prepare an aqueous solution (2). The silica carrier absorbing the aqueous solution (1) was added to the beaker prepared with the aqueous solution (2), and the mixture was allowed to stand at room temperature for 20 hours.
Next, 8.00 g of hydrazine monohydrate was gradually added to this at room temperature with stirring. After adding hydrazine monohydrate, the mixture was stirred for 4 hours. Then the catalyst was filtered off and
After deionized water was circulated for 0 hours for washing, it was dried in an air stream at 110 ° C. for 4 hours.

Next, 0.266 g of sodium tellurite was weighed out, and 45 g of pure water was added to prepare an aqueous solution (3). The metal palladium-supported catalyst was added to the aqueous solution (3) to absorb the whole amount of the aqueous solution (3). Then, it was dried at 110 ° C. for 4 hours under an air stream to obtain a tellurium-added metal palladium-supported catalyst.

In another beaker, 23.98 g of silicotungstic acid 26 hydrate was weighed, and pure water was added thereto to dissolve it to 45 ml to prepare an aqueous solution (4). The metallic palladium-supported catalyst washed with an acidic solution was added to the beaker in which the aqueous solution (4) was prepared, and the whole amount of the aqueous solution (4) was absorbed. Then, it was dried at 110 ° C. for 4 hours under an air stream to obtain a catalyst for acetic acid production.

[0107]   By the above operation, about 5 liters of the catalyst, which is the required filling amount for the reactor, was produced.

[0108]   Process overview   The outline of the processes used in the examples and comparative examples will be described with reference to FIG.

As the reactor (6), a vertical annular reactor with a jacket was used. The heat generated by the reaction was removed by vaporizing the water supplied to the jacket, and the temperature in the reactor was controlled.

In the gas-liquid separation device (7), the gas that has been supplied in a gas-liquid mixed state after passing through the reactor is mainly composed of unreacted ethylene gas, a gas composed of unreacted oxygen, carbon dioxide gas, nitrogen, etc. And liquid such as water. The separated liquid containing acetic acid is taken out of the system through the acetic acid take-out line (9). On the other hand, a part of the gas is discharged to the outside of the system through the purge line (11), but most of it is supplied with new ethylene from the ethylene supply line (17) through the flow meter (13) and also with the oxygen supply line (15). Oxygen is added to the reactor and returned to the reactor again.

The process control, in particular, the operation output (MV) of the raw material supply amount is automatically performed as follows. The raw material concentration at the inlet of the reactor (6) is calculated by the calculation device (19) from the measured values of each control device and the measurement device, and is input as the control amount (PV) of the concentration controller (18). In the concentration controller (18), the target value (SV) given in advance
Based on the deviation of the PV, a new flow rate target value to be given to the flow rate control device (16) is calculated, and the MV is determined by the resulting configuration of concentration-flow rate cascade control by a so-called PID controller.

The control valves used in the pressure control device (10) and the ethylene flow rate control device (16) were both VSM type control valves manufactured by Yamatake Co., which had a CV value of 0.05 and a linear characteristic (LC).
And is connected to 1/2 inch piping.

Example 1 In a process in which a control line was configured as shown in FIG. 2, the composition of the raw material gas at the reactor inlet was adjusted to a volume ratio (vol%) of oxygen: ethylene: water: nitrogen = 4.5: 8. ．
The concentration was adjusted to 5:25:62, and the concentration-flow rate cascade control was turned on.

As a result, the process exhibited very stable ethylene concentration behavior as shown in FIG.

The square deviation, which is an index showing the control performance, that is, the size of the area obtained by squaring the deviation from the target ethylene concentration was 0.187 (vol%) ² , which was very small. The behavior of the pressure at this time was very stable as shown in FIG. 9, and the squared deviation of the pressure was 0.00182 MPa ² .

PI of the ethylene concentration controller which is the primary side of the concentration-flow rate cascade control at this time
The D parameter had a proportional band of 200% and an integration time of 600 seconds.

Example 2 In a process in which a control line was configured as shown in FIG. 2, the composition of the raw material gas at the reactor inlet was adjusted to a volume ratio (vol%) of oxygen: ethylene: water: nitrogen = 4.5: 8. ．
Adjust to be 5:25:62, and leave the concentration-flow rate cascade control turned on, 3
After 0 minutes, the ethylene concentration target value (SV) was changed from 8.5 vol% to 9.0 vol.
The operation to change to% was added.

Despite such an operation, the unit of the present invention reached the target value in a very stable manner as shown in FIG. 10 in about one hour without overshoot or unstable operation. The squared deviation of the ethylene concentration from the target value at this time is 6.48 (vo
1%) ² , and the squared deviation of the pressure was 0.00175 MPa ² .

At this time, the PID parameter of the ethylene concentration controller continues to be proportional band 2.
It was 00% and the integration time was 600 seconds.

Comparative Example 1 As shown in FIG. 3, a reaction process was constructed in which the purge flow rate was controlled so that the ethylene concentration was constant.

FIG. 3 shows the same process as in Examples 1 and 2, but the operation command signal MV of the concentration controller (18) is connected so as to open and close the control valve of the purge line (11), and ethylene The control valve of the supply line (17) was fixed at an opening of 17.7% (fully closed at 0%).

In this process, the control was turned on after the reactor inlet composition was adjusted so that the volume ratio (vol%) was oxygen: ethylene: water: nitrogen = 4.5: 8.5: 25: 60.5. Then, after 30 minutes, the ethylene concentration target value (SV) was changed from 8.5 vol% to 9%.
． The operation to change to 0 vol% was added.

As a result, as shown in FIG. 11, the purge flow rate was increased in order to increase the ethylene concentration, and the operation of promoting the inflow of ethylene into the system was carried out. The increase in the flow rate was insufficient to reach the target value of ethylene concentration, and the target value was not reached even after 4 hours, so the control was abandoned.

[0124]   The squared deviations of ethylene concentration and pressure at this time are 22.83 (vol%) ²  And 0.203 MPa²And applying a disturbance about 100 times the pressure as compared with Example 2.
However, the ethylene concentration control results are not very good,
I couldn't reach my goal.

The PID parameter of the ethylene concentration controller was set to a proportional band of 60% and an integration time of 1200 seconds as a result of considering the influence on the ethylene concentration and the disturbance on the pressure.

Comparative Example 2 As shown in FIG. 4, a reaction process was constructed in which the purge amount was controlled so that the pressure became constant. FIG. 4 shows the same process as in Examples 1 and 2, but the control valve of the ethylene supply line (17) was fixed at an opening of 17.4% (fully closed at 0%).

In this process, the reactor inlet composition was adjusted so that the volume ratio (vol%) was oxygen: ethylene: water: nitrogen = 4.5: 8.5: 25: 62, and then control was turned on. .

As shown in FIG. 12, as a result, it was observed that the ethylene flow rate slightly fluctuated due to the fluctuation of the purge amount performed to eliminate the pressure deviation, and the ethylene concentration was gradually decreased for 4 hours. Since there was no sign of recovery even if the temperature exceeded the limit, control was abandoned.

The squared deviation of the ethylene concentration at this time was 6.09 (vol%) ^2, which was 30 in Example 1.
It was more than doubled, and the effect of keeping the ethylene concentration at its target value was not recognized. The behavior of the pressure at this time is shown in FIG. The square deviation of the pressure at this time is 0.00108 MPa ² , which is a control result at the same level as in the first embodiment.

Example 3 Next, the present invention will be described using a reaction process of obtaining ethyl acetate from ethylene and acetic acid in the presence of a heteropolyacid-based catalyst for producing ethyl acetate.

Outline of Reaction and Process As shown in FIG. 5, ethylene and acetic acid as raw materials are supplied to a reactor, ethyl acetate is separated through a gas-liquid separation device, and a gas containing an inert material and an unreacted raw material is again generated. A process was constructed in which a recycling system to the reactor was constructed. 5 is shown in FIG.
2 shows the same process as the above, but in FIG. 2, the line to which oxygen is supplied is used as the acetic acid supply line (24) and the acetic acid flow controller (23), and the calculation device (2
In 5), the program is changed to calculate the ethylene concentration from the flow rate of acetic acid instead of the flow rate of oxygen.

Preparation Method of Catalyst Natural silica (KA-0 manufactured by Sudhemie AG) was used as a carrier, and this was dried for 4 hours in a hot air dryer previously adjusted to 110 ° C. Weigh 3266.5 g of phosphotungstic acid (H ₃ PW ₁₂ O ₄₀ ) and 6.6 g of lithium nitrate,
750 ml of pure water was added and uniformly dissolved to obtain a Li _0.1 H _2.9 PW ₁₂ O ₄₀ aqueous solution. Next, this aqueous solution was diluted with pure water so as to be 1700 ml, and uniformly stirred. Subsequently, 2790 g of the dried carrier was weighed out, soaked in an aqueous solution and well stirred to sufficiently impregnate it. The carrier impregnated with the liquid was air-dried for 1 hour and then dried for 5 hours with a hot air dryer adjusted to 150 ° C. The weight of the catalyst thus obtained was 5675 g.

About 5 liters of the catalyst obtained by the above procedure was charged into the reactor shown in FIG. 5, the reaction peak temperature of the catalyst bed was 170 ° C., the reaction pressure was 0.8 MPa (gauge pressure), the space velocity (GH).
SV) was 1500 Hr ^-1 and the ratio of the mixed gas supplied to the reactor was adjusted so that the ratio of ethylene: acetic acid: water: nitrogen was 78.5: 8.0: 4.5: 9.0.

After 30 minutes, the target concentration value (SV) of the raw material ethylene was changed from 78.5% by volume to 1%.
． The operation of increasing the volume by 0% was performed.

The results showed stable behavior as shown in FIG. 14, and converged to the target ethylene concentration after about 2 hours. The squared deviation between ethylene concentration and pressure is 5.54 (vol%) ²
And 0.00136 MPa ² .

Example 4 The present invention is illustrated using a process for producing allyl acetate from propylene, acetic acid and oxygen in the gas phase.

Outline of Reaction and Process As shown in FIG. 6, a process for producing allyl acetate from propylene as a raw material, acetic acid, and oxygen was constructed.

FIG. 6 shows the same process as FIG. 2, but the line used as the ethylene feed line in FIG. 2 is the propylene feed line (27) and the propylene flow controller (26).
), A new acetic acid supply line (29) and acetic acid flow controller (
28) is added and functioning.

The ethylene concentration analyzer in FIG. 2 is replaced by a propylene concentration analyzer (30), and the calculator (31) is programmed to calculate the propylene concentration from these raw material flow rates and the like.

Preparation Method of Catalyst To 1800 ml of an aqueous solution containing 45.6 g of sodium tetrachloropalladate (Na ₂ PdCl ₄ ) and 5.2 g of copper chloride (CuCl ₂ ) was added 5 l of a silica carrier having a particle diameter of 5 mm to form a solution. It was completely impregnated. Next, add this to sodium hydroxide (Na
It was added to 4 l of an aqueous solution containing 29.6 g of OH), treated with an alkali for 20 hours at room temperature, and then reduced with hydrazine hydrate. After the reduction, the catalyst was washed with water until chlorine ions were not observed, then dried at 110 ° C. for 4 hours, then put into 1800 ml of an aqueous solution containing 150 g of potassium acetate (KOAc) to absorb the whole solution, and then to 100 again. It was dried at 0 ° C. for 20 hours.

5 l of the catalyst thus prepared was filled in a stainless reaction tube shown in FIG. 6, and propylene 30%, acetic acid 7.0%, oxygen 7.0%, water 14.0% and nitrogen 42.0.
% Of the mixed gas is supplied so that the GHSV becomes 2100 Hr ^-1, and the reaction temperature is 165 ° C.
After adjusting the conditions of pressure 0.5 MPa (gauge pressure), concentration-flow rate cascade control was performed. After 30 minutes, the propylene concentration SV was increased from 30 vol% to 30.5 vol%.

The results converged to the target propylene concentration after about 2 hours while exhibiting stable behavior as shown in FIGS. The square deviation between the propylene concentration and the pressure is 6.76 (
vol%) ² and 0.00127 MPa ² .

Example 5 The present invention will be described using a process for producing vinyl acetate using a palladium-based catalyst in the presence of ethylene, acetic acid and oxygen.

Outline of Reaction and Process As shown in FIG. 7, a process for producing vinyl acetate from ethylene, acetic acid and oxygen as raw materials was constructed.

FIG. 7 shows the same process as in FIG. 2, but is equipped with an acetic acid supply line (29) and an acetic acid flow controller (28) as in FIG. It is programmed to calculate ethylene concentration.

Preparation Method of Catalyst An aqueous solution containing 100 g of sodium tetrachloropalladate (Na ₂ PdCl ₄ ) and 13 g of tetrachloroauric acid tetrahydrate was added to natural silica (Zudhemie AG).
Sodium metasilicate 320 after soaking 5 l of KA-0)
It was added to 4 l of an aqueous solution containing g and allowed to stand for 20 hours. Then hydrazine hydrate 1
After adding 9.0 g, sodium tetrachloropalladate and tetrachloroauric acid tetrahydrate were reduced to metal, washed with water, and then dried at 110 ° C. for 4 hours. Then, the carrier containing the metal palladium and gold was put into an aqueous solution of 4.0 g of tin acetate to absorb the whole liquid, and then dried at 110 ° C. for 4 hours. Then potassium acetate 165
The above-mentioned carrier containing metallic palladium was put into an aqueous solution containing g to absorb the whole liquid, and then dried at 110 ° C. for 4 hours.

The reaction tube was filled with 5 l of the catalyst thus obtained, the reaction temperature was 170 ° C., the reaction pressure was 0.8 MPa (gauge pressure), and the ratio of ethylene, oxygen, acetic acid, water, and nitrogen was 60: 4.
The gas mixed so as to have a ratio of 15: 15: 6 was introduced by GHSV2200Hr ^-1 and reacted.

The results showed stable behavior as shown in FIG. 14, and converged to the target ethylene concentration after about one and a half hours. The square deviation of ethylene concentration and pressure is 5.57 (vol%) ²
And 0.00101 MPa ² . (Industrial Applicability) As described above, the reaction can be carried out efficiently and stably by using the method for adjusting the concentration of the raw material in the gas phase catalytic reaction of the present invention and the method for controlling the process by the adjusting method. Is possible.

In particular, in the method for adjusting the concentration of raw materials in the gas phase catalytic reaction of the present invention, and the method for producing a lower fatty acid and the method for producing a lower fatty acid ester using the method for controlling the process according to the adjustment method, conventional process control is performed. Compared with the method, it is possible to carry out the reaction efficiently and stably over a long period of time.

[Brief description of drawings]

The drawings are respectively a process diagram showing an embodiment of the present invention, a schematic diagram of an experimental apparatus used in Examples and Comparative Examples, and a graph of results according to Examples and Comparative Examples.

FIG. 1 is a conceptual diagram for explaining the concept of the present invention. The numbers in the figure are as follows. 1: Reactor 2: Product and other separation device 3: Product line 4: Purge line 5: Raw material supply line

FIG. 2 is a schematic diagram of an apparatus used in Examples 1 and 2. The solid line shows the process line, the dotted line shows the signal line, and the single broken line shows the control line. The numbers in the figure are as follows. 6: Reactor 7: Gas-liquid separator 8: Level controller 9: Acetic acid take-out line 10: Pressure controller 11: Purge line 12: Ethylene concentration analyzer 13: Flow meter 14: Oxygen flow controller 15: Oxygen supply line 16: Ethylene flow rate control device 17: Ethylene supply line 18: Concentration controller 19: Calculation device

FIG. 3 is a schematic diagram of an apparatus used in Comparative Example 1. The solid line shows the process line, the dotted line shows the signal line, and the single broken line shows the control line. The numbers in the figure are the same as those shown in FIG.
Is the same as. 20: Pressure gauge 21: Flow meter

4 is a schematic diagram of an apparatus used in Comparative Example 2. FIG. The solid line shows the process line, the dotted line shows the signal line, and the single broken line shows the control line. Figure 2 except for those shown below in the legend in the figure
Is the same as. 21: Flowmeter 22: Densitometer

FIG. 5 is a schematic diagram of an apparatus used in Example 3. The solid line shows the process line, the dotted line shows the signal line, and the single broken line shows the control line. Figure 2 except for those shown below in the legend in the figure
Is the same as. 23: Acetic acid flow controller 24: Acetic acid supply line 25: Calculation device

FIG. 6 is a schematic diagram of an apparatus used in Example 4. The solid line shows the process line, the dotted line shows the signal line, and the single broken line shows the control line. Figure 2 except for those shown below in the legend in the figure
Is the same as. 26: Propylene flow controller 27: Propylene supply line 28: Acetic acid flow controller 29: Acetic acid supply line 30: Propylene concentration measuring device 31: Calculation device

FIG. 7 is a schematic diagram of an apparatus used in Example 5. The solid line shows the process line, the dotted line shows the signal line, and the single broken line shows the control line. Figure 2 except for those shown below in the legend in the figure
Is the same as. 28: Acetic acid flow controller 29: Acetic acid supply line 32: Calculation device

[Figure 8]   5 is a graph showing the results of Example 1.

[Figure 9]   5 is a graph showing the results of pressure in Example 1.

[Figure 10]   5 is a graph showing the results of Example 2.

FIG. 11   9 is a graph showing the results of Comparative Example 1.

[Fig. 12]   9 is a graph showing the results of Comparative Example 2.

[Fig. 13]   9 is a graph showing the results of pressure in Comparative Example 2.

FIG. 14   9 is a graph showing the results of Example 3.

FIG. 15   9 is a graph showing the results of Example 4.

FIG. 16   9 is a graph showing the results of Example 4.

FIG. 17   9 is a graph showing the results of Example 5.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KR, KZ, LC, LK, LR, LS , LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, R U, SD, SE, SG, SI, SK, SL, TJ, TM , TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW

Claims (18)

[Claims] 1. In the adjustment of the raw material concentration in the gas supplied to the reactor in the gas phase catalytic reaction process having a recycle system, the raw material concentration in the gas of the process is measured, and the measured value is newly added to the process. A method for adjusting the concentration of a raw material, which comprises controlling the concentration of the raw material in the gas supplied to the reactor as a result of determining and supplying the supply amount of the additional raw material. 2. The method according to claim 1, wherein the gas phase catalytic reaction is a fixed bed gas phase catalytic reaction. 3. The reactor according to claim 1, wherein the reactor is a multi-tube type and / or a multi-layer type.
The method described. 4. The method according to claim 1, wherein the raw material concentration is measured immediately before the reactor. 5. The method according to claim 1, wherein the supply amount of the newly added raw material is adjusted by an adjusting means provided in the raw material supply line. 6. A method for controlling a reaction process, wherein in the control of the gas-phase catalytic reaction process, at least one of the controlling methods is the method for adjusting the raw material concentration according to any one of claims 1 to 5. 7. The method for adjusting the concentration of lower olefin and / or oxygen in a reactor, which comprises producing a lower fatty acid from a lower olefin and oxygen in the presence of a catalyst, according to claim 1. A method for producing a lower fatty acid, which is a method for adjusting a lower fatty acid. 8. A method for producing a lower fatty acid, which comprises producing a lower fatty acid from a lower olefin and oxygen in the presence of a catalyst, the production process being controlled by the method for controlling a reaction process according to claim 6. . 9. The method according to claim 7, wherein the reaction is carried out in the presence of water in the method of producing a lower fatty acid from a lower olefin and oxygen in the presence of a catalyst. 10. The lower olefin is ethylene, propylene, 1-butene, 2
-The method according to any one of claims 7 to 9, which is at least one selected from the group consisting of butene and butadiene. 11. A method for adjusting the concentration of a lower olefin and / or a lower fatty acid in a reactor, which comprises producing a lower fatty acid ester from a lower olefin and a lower fatty acid in the presence of a catalyst. A method for producing a lower fatty acid ester, which is the adjusting method described in 1. 12. A lower fatty acid ester, which comprises producing a lower fatty acid ester from a lower olefin and a lower fatty acid in the presence of a catalyst, the production process being controlled by the method for controlling a reaction process according to claim 6. Manufacturing method. 13. The method for producing a lower fatty acid ester according to claim 11 or 12, which comprises producing a lower fatty acid ester from a lower olefin and a lower fatty acid in the presence of a catalyst, and performing the reaction in the presence of water. 14. A method for adjusting the concentration of lower olefin, oxygen and / or lower fatty acid in a reactor, which comprises producing a lower fatty acid ester from lower olefin, oxygen and lower fatty acid in the presence of a catalyst. 5. The method for producing a lower fatty acid ester, which is the adjusting method according to any one of 5 above. 15. A method for producing a lower fatty acid ester from a lower olefin, oxygen, and a lower fatty acid in the presence of a catalyst, the production process being controlled by the method for controlling a reaction process according to claim 6. Method for producing lower fatty acid ester. 16. A method for producing a lower fatty acid ester from a lower olefin, oxygen and a lower carboxylic acid in the presence of a catalyst, wherein the reaction is carried out in the presence of water,
The method according to claim 14 or 15. 17. The lower olefin is ethylene, propylene, 1-butene, 2
-The method according to any of claims 11 to 16, which is at least one selected from the group consisting of butene and butadiene. 18. The lower fatty acid is at least one selected from the group consisting of formic acid, acetic acid, propionic acid, acrylic acid and methacrylic acid.
The method described in any one of.