WO2017146024A1

WO2017146024A1 - Method for producing conjugated diolefin

Info

Publication number: WO2017146024A1
Application number: PCT/JP2017/006302
Authority: WO
Inventors: 佑太中澤; 成喜奥村; 文吾西沢; 友洋小畑
Original assignee: 日本化薬株式会社
Priority date: 2016-02-22
Filing date: 2017-02-21
Publication date: 2017-08-31
Also published as: JP2017149655A

Abstract

Provided is a method for producing a conjugated diolefin by causing a monoolefin with a carbon number of 4 or greater to undergo a gas-phase contact oxidative dehydrogenation reaction in the presence of a catalyst, wherein damage to the catalyst is minimized and the method for producing a conjugated diolefin has superior long-term stability. A method for producing a conjugated diolefin by causing a monoolefin with a carbon number of 4 or greater to undergo a gas-phase contact oxidative dehydrogenation reaction in the presence of a catalyst for conjugated diolefin production, said method for producing a conjugated diolefin being characterized in that the catalyst, which has a pre-use composition of active components expressed by formula 1, is regenerated after use, and a post-regeneration catalyst having a cumulative relative surface area of 5.17m²/g or less is used. Formula 1: Mo₁₂Bi_aFe_bCo_cNi_dX_eY_fZ_gO_h

Description

Method for producing conjugated diolefin

The present invention is a process for producing a conjugated diolefin by subjecting a monoolefin having 4 or more carbon atoms to gas phase catalytic oxidative dehydrogenation in the presence of a catalyst, and producing a conjugated diolefin having excellent long-term stability. Regarding the method.

Conventionally, butadiene, which is a raw material for synthetic rubber and the like, has been industrially produced by thermal decomposition and extraction of naphtha fractions. There is a need for a manufacturing method. In view of this, a method for vapor-phase catalytic oxidative dehydrogenation of n-butene in the presence of a catalyst from a mixed gas containing butenes (also expressed as n-butene) and molecular oxygen has attracted attention. However, coke-like substances from reaction products and / or reaction by-products are deposited or deposited in the reactor, that is, on the catalyst surface and inside, the inert material, the inner wall of the reaction tube, and the post-process equipment. It may cause various troubles such as obstruction of the reaction gas flow, blocking of the reaction tube, and accompanying plant shutdown and yield reduction. In order to avoid these problems, industrial plants generally stop the reaction before clogging with the coke-like substance, and remove the coke-like substance by raising the temperature of the heat medium circulating in the reactor. To do. Moreover, as a production | generation mechanism of a coke-like substance, the following is assumed, for example. That is, when using a composite metal oxide catalyst containing molybdenum, it is caused by polymerization of various olefins and condensation of high-boiling compounds starting from a molybdenum compound that sublimates and precipitates in the reactor, and in the catalyst and reactor. Production of high-boiling compounds by polymerization of various olefins starting from abnormal acid-base points and radical formation points and condensation of high-boiling compounds, Diels-Alder reaction with conjugated dienes and other olefinic compounds, and locally in the reactor Examples include those caused by condensation at low temperatures, and various other mechanisms are known.

Furthermore, another problem in the method for producing butadiene is damage to the catalyst. This is unique to the process of producing conjugated diolefins, where the shape of the catalyst changes from a packed catalyst shape to a catalyst piece due to a long-term reaction, that is, fragments, granules, or even powders change in shape or deteriorate (break). There are concerns about the following problems. That is, an increase in pressure loss due to accumulation of damaged catalyst pieces in the reactor, an undesirable side reaction due to the catalyst locally accumulated in the reactor, and contamination of the broken catalyst pieces into the subsequent purification system, etc. The following literatures are known as countermeasures in the prior art.

Patent Document 1 discloses the correlation between the change rate of the outer diameter of the catalyst before and after the reaction and the change in strength. In the tableting method, which is a catalyst molding method of Patent Document 1, the mechanical strength of the catalyst is increased, while the catalyst active component is molded so as to be densely aggregated. / Or the point that coke-like substances are likely to deposit compared to catalysts formed by other molding methods, the heat of reaction is likely to accumulate inside the catalyst, the yield is reduced, and the reaction runaway occurs, and the production of the catalyst itself. The problem is that it is bad. Patent Document 2 discloses the correlation between the crushing rate in the packed catalyst and the amount of coke-like substance produced, but there is no disclosure regarding the catalyst or reaction conditions for suppressing the crushing rate in the long-term reaction.

One means for solving the damage of the catalyst is to improve the hardness of the catalyst itself. The following documents are known as methods for improving general mechanical strength. Patent Documents 3 to 9 all relate to a catalyst for adding an organic auxiliary agent and / or an inorganic auxiliary agent having a specific particle size distribution, fiber length, acid strength, and the like, or a method for producing the same.

Assuming that the catalyst is a ceramic material, as a method for improving the hardness in addition to the addition of the inorganic auxiliary agent, as in Non-Patent Document 1, control of the pore structure can be mentioned. The failure of the catalyst is considered to be caused by the stress inside the catalyst in the long-term reaction or regeneration treatment, and it can be estimated that the stress increases around the pores, leading to the failure. That is, it is preferable to reduce the pores in order to suppress the damage of the catalyst. However, if the pores are reduced, the reaction field on the surface of the catalyst is reduced, resulting in a decrease in performance such as catalyst activity. No technology has been pursued in terms of determining the pore structure.

In addition, from the viewpoint of economic efficiency in an industrial plant, it is naturally important that butadiene which is the target product can be obtained in a high yield. A technology that maintains yield and has excellent long-term stability of production activities is desired, and as described above, methods for improving catalysts and processes have been disclosed. However, in reality, a regeneration step is performed after the reaction, In spite of the investigation of the technology for reusing the catalyst, there has been no disclosure of the technology that has been investigated for the physical properties of the regenerated catalyst.

JP 2011-241208 A JP 2012-046509 A Japanese Patent No. 3313863 Japanese Patent No. 4863436 JP 2002-273229 A Japanese Patent No. 5388897 International Publication No. 2012/036038 Japanese Patent No. 5628936 Japanese Patent Laid-Open No. 07-16463

The present invention is a method for producing a conjugated diolefin by subjecting a monoolefin having 4 or more carbon atoms to gas phase catalytic oxidative dehydrogenation in the presence of a catalyst, which suppresses damage to the catalyst and improves long-term stability. It aims at providing the manufacturing method of the outstanding conjugated diolefin.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have conducted a gas-phase catalytic oxidative dehydrogenation reaction of a monoolefin having 4 or more carbon atoms, preferably n-butene, in the presence of a catalyst. It is a method for producing a conjugated diolefin, preferably butadiene, and it is found that the use of a post-regeneration catalyst that satisfies a certain range with a cumulative specific surface area in the reaction can suppress breakage and has excellent long-term stability. The present invention has been completed.

That is, the present invention is (1) a method for producing a conjugated diolefin by subjecting a monoolefin having 4 or more carbon atoms to a gas phase catalytic oxidative dehydrogenation reaction in the presence of a catalyst for producing a conjugated diolefin. The conjugated diolefin is characterized by using a regenerated catalyst having a cumulative specific surface area of 5.17 m ² / g or less, which is regenerated after using the catalyst represented by the following formula 1 as the active component composition of the catalyst: Manufacturing method,
_{_{_{_{Mo 12 Bi a Fe b Co c}}}} Ni d X e Y f Z g O h ···· ( Equation 1)
(In the formula, X represents at least one element of an alkali metal selected from lithium, sodium, potassium, rubidium, and cesium, and Y represents at least one element of an alkaline earth metal selected from magnesium, calcium, strontium, and barium. Z represents at least one element selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, antimony, tungsten, lead, zinc, cerium, thallium, and a, b, c, d, e, f and g each represent an atomic ratio of each component to molybdenum 12, and 0.2 ≦ a ≦ 2.0, 0.6 <b <3.4, 5.0 <c <8.0, 0 <d < 3.0, 0 <e <0.5, 0 ≦ f ≦ 4.0, 0 ≦ g ≦ 2.0, and h is a numerical value that satisfies the oxidation state of other elements).
(2) The catalyst is a molded catalyst in which a carrier is coated with a catalytically active component, the resulting molded catalyst has an average particle size of 3.0 mm to 10.0 mm, and the loading ratio of the catalytically active component is 20% by weight. The production method according to (1), which is not less than 80% by weight,
(3) The production method according to (1) or (2), wherein the monoolefin having 4 or more carbon atoms is n-butene and the conjugated diolefin is 1,3-butadiene,
About.

The present invention relates to a method for producing a conjugated diolefin by subjecting a monoolefin having 4 or more carbon atoms to gas phase catalytic oxidative dehydrogenation in the presence of a catalyst, wherein the specific surface area has a specific range of regeneration. By using a post-catalyst for the reaction, there is provided a method for producing a conjugated diolefin having excellent long-term stability that can suppress breakage and maintain the yield.

The present invention is a reaction for producing a conjugated diolefin by a gas phase catalytic oxidative dehydrogenation reaction from a mixed gas containing a monoolefin having 4 or more carbon atoms and molecular oxygen, and preferably comprises n-butene and molecular oxygen. This is a method for producing butadiene, preferably 1,3-butadiene, from a mixed gas containing it by a gas phase catalytic oxidative dehydrogenation reaction. Next, a method for producing a conjugated diolefin using a post-regeneration catalyst in which a monoolefin having 4 or more carbon atoms is subjected to gas phase catalytic oxidative dehydrogenation reaction and a cumulative specific surface area satisfies a specific range will be described.

The monoolefin having 4 or more carbon atoms in the present invention is an unsaturated hydrocarbon having 4 or more carbon atoms containing one carbon-carbon double bond, butene, pentene, hexene, heptene, octene, nonene and N-butene means 1-butene, trans-2-butene, cis-2-butene, isobutylene, a single component gas or a mixed gas containing at least one component Conjugated diolefin is a hydrocarbon having two carbon-carbon double bonds bonded through one single bond, preferably butadiene, particularly preferably 1,3-butadiene And

As a method for regenerating a catalyst used for producing a conjugated diolefin by producing a conjugated diolefin by subjecting a monoolefin having 4 or more carbon atoms to gas phase catalytic oxidative dehydrogenation in the presence of a catalyst for producing a conjugated diolefin, For example, a gas having the following composition may be supplied under conditions of 200 ° C. or higher and lower than 400 ° C., preferably 200 ° C. or higher and 350 ° C. or lower, as the heating medium circulating in the reactor filled with the catalyst. More preferably, the temperature of the heat medium circulating in the reactor is constant at 200 ° C. or higher and lower than 400 ° C., and constant at 200 ° C. or higher and 350 ° C. or lower. The composition of the gas is greater than 0% by volume of water vapor and 42% by volume or less and greater than 0% by volume of oxygen and 21% by volume or less.

The cumulative specific surface area is one of the parameters indicating the fine pore properties of the catalyst. If the reaction causes carbon deposition on the catalyst surface and the pores are blocked, the cumulative specific surface area becomes smaller, and further the carbon deposition proceeds. If the pores are enlarged and then carbon is removed by regeneration, the cumulative specific surface area becomes larger. In particular, if the accumulated specific surface area of the catalyst after regeneration is too small, the space in which the catalyst reaction proceeds is reduced, which causes a deterioration in the reaction results such as a decrease in the activity of the catalyst. In the present invention, a regenerated catalyst having a cumulative specific surface area of 5.17 m ² / g or less is used. Further, when the cumulative specific surface area is too large because there are cases strength of the catalyst is low, more preferably 1.37 m ² / g or more 5.17 m ² / g or less, more preferably 2.07m ² / g or more 4 .48m ² / g, more preferably not more than 2.77m ² / g or more 3.78m ² / g.

The method for measuring the cumulative specific surface area is not particularly limited, but it is preferably measured by a mercury intrusion method. Moreover, it is preferable to calculate a measured value from the pore distribution data with a pore diameter of 0.0036 μm to 400 μm.

The cumulative specific surface area of the pre-reaction catalyst is a physical property value unique to the produced catalyst, and is controlled to a physical property suitable for the target reaction by a known technique. Specifically, catalyst pores can be designed by changing the catalyst composition, molding method, firing method, and the like. The cumulative specific surface area of the regenerated catalyst changes as described above in the course of catalytic reaction and regeneration. More specifically, the supply gas composition and supply gas space velocity in the reaction and regeneration, the form of the reactor, the temperature of the heat medium circulated in the reactor, and the temperature control ability in the reactor are low, the reactor The internal temperature is not maintained uniformly, and a local temperature deviation occurs, so that an unfavorable space is generated for the catalytic reaction to proceed, and this is influenced by phenomena that induce various troubles.

The “coke-like substance” in the present invention is produced by at least one of a reaction raw material, a target product and a reaction by-product in the reaction for producing a conjugated diolefin, and details of its chemical composition and production mechanism. Is unknown, but deposits or adheres to the catalyst surface and inside, inert materials, reaction tube inner walls and post-processing equipment, especially in industrial plants, obstructing the flow of reaction gas, blocking the reaction tube and accompanying them. It is a causative substance that causes various troubles such as reaction shutdown.

The mechanism by which the coke-like substance can be removed in the catalyst regeneration step of the present invention has not been elucidated in detail and is unclear, but the coke-like substance produced by the gas phase catalytic oxidative dehydrogenation reaction is the catalyst in the reaction tube. When adhering to walls, inert materials, etc., it is considered that a temperature suitable for the decomposition to proceed gradually without causing rapid combustion is considered necessary. When the heat medium is 400 ° C. or higher, the coke-like substance burns rapidly and adheres to the catalyst, and the heat generation causes a change in the crystal structure of the catalyst, causing deterioration and further combustion. Gases can cause pressure on the catalyst and break it, and sudden heat generation inside the reaction tube can cause damage to the reactor. Further, when the heat medium is lower than 200 ° C., the combustion does not proceed and the regeneration effect is not sufficiently exhibited, or the regeneration time may become long, and the economic efficiency deteriorates due to the long plant stoppage period. There is a risk.

Further, by adding water vapor to the diluted oxygen gas supplied to the reactor, the coke-like substance can be effectively removed from the reactor even when the temperature of the heating medium is low. Regarding the water vapor volume ratio and / or oxygen volume ratio of the gas supplied to the reactor, there is no particular limitation as long as it is 0% to 42% by volume for water vapor and greater than 0% by volume to 21% by volume for oxygen. A coke-like substance by supplying a gas containing more than 0% by volume of oxygen and containing 21% by volume or less of oxygen, and then supplying a gas containing more than 0% by volume and less than 42% by volume of water vapor to the reactor Is preferably removed. More preferably, after supplying a gas containing oxygen greater than 0% by volume and not greater than 21% and not containing water vapor to the reactor, the water vapor is then greater than 0% by volume and not greater than 42% by volume and oxygen 0%. When a gas containing greater than 21% by volume and less than 21% by volume is supplied to the reactor, the coke-like substance can be more effectively suppressed.

The water vapor capacity ratio and / or oxygen capacity ratio of the gas supplied to the reactor can be adjusted, for example, with nitrogen or the like.

When the composition of the gas to be supplied is switched, the generation rate is 95% or less of the maximum generation rate after the generation rate of CO ₂ and CO discharged under the conditions is maximized, and the generation rate gradually decreases. When is stable. The nature and amount of coke-like substances differ depending on the reaction conditions, reaction scale, reaction period, and catalyst performance of the gas phase catalytic oxidative dehydrogenation performed, and the combustion behavior differs. The time of switching may be appropriately changed within the above-mentioned range. Furthermore, where production rate of the discharged is CO ₂ and CO and are the production rate of CO ₂ and CO generated during processing, CO ₂ and CO amount contained originally in the air is being divided calculate Is.

The heating rate of the heating medium during regeneration is not particularly limited, but is preferably in the range of 1 ° C./h to 200 ° C./h. If the rate of temperature rise is higher than 200 ° C./h, rapid combustion may be caused and sufficient effective regeneration may not be performed. On the other hand, if the rate of temperature rise is slower than 1 ° C./h, the time required for regeneration becomes long and the economy may deteriorate.

It is more preferable to combine the operations of the temperature of the heat medium circulating in the reactor, the water vapor capacity rate and / or oxygen capacity rate contained in the gas supplied to the reactor, and the heating rate, and circulate in the reactor. The heat medium to be regenerated with a gas containing oxygen that is greater than 0% by volume and less than or equal to 21% by volume under certain conditions at 200 ° C. or more and 350 ° C. or less, and then a gas that contains greater than 0% by volume and less than 42% by volume of water vapor. It is most preferable to carry out the step of supplying the gas so as to reduce the production rate of CO ₂ and CO discharged from the reaction tube outlet gas as much as possible to an appropriate production rate. When this process is repeated twice, the temperature of the heat medium in the first process and the second process is preferably different, and the temperature of the heat medium in the second process is higher than the temperature of the heat medium in the first process. More preferred. When this process is repeated twice or more, the temperature of the heat medium may be different for each process. In addition, the appropriate production rate is appropriately determined because it varies depending on the reaction conditions, reaction scale, reaction period, and catalyst performance of the gas phase catalytic oxidative dehydrogenation performed.

The number of regenerations is not limited, and can be performed once or multiple times. If the accumulated specific surface area after regeneration satisfies the range described above, the regenerated catalyst can be continuously subjected to the reaction.

In the present invention, the catalyst before use contains a catalytically active component having a composition represented by the following (formula 1).
_{_{_{_{Mo 12 Bi a Fe b Co c}}}} Ni d X e Y f Z g O h ···· ( Equation 1)
(In the formula, X represents at least one element of an alkali metal selected from lithium, sodium, potassium, rubidium, and cesium, and Y represents at least one element of an alkaline earth metal selected from magnesium, calcium, strontium, and barium. Z represents an element, and Z represents at least one element selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, antimony, tungsten, lead, zinc, cerium, thallium, and a, b, c, d, e, f and g each represent an atomic ratio of each component to molybdenum 12, and 0.2 ≦ a ≦ 2.0, 0.6 <b <3.4, 5.0 <c <8.0, 0 <d < 3.0, 0 <e <0.5, 0 ≦ f ≦ 4.0, 0 ≦ g ≦ 2.0, and h is a numerical value that satisfies the oxidation state of other elements.)

The raw material of each metal element for obtaining the catalyst used in the present invention is not particularly limited, but nitrates, nitrites, sulfates, ammonium salts, organic acid salts, acetates, carbonates containing at least one metal element. Secondary carbonates, chlorides, inorganic acids, inorganic acid salts, heteropolyacids, heteropolyacid salts, hydroxides, oxides, metals, alloys, etc., or a mixture thereof can be used as specific examples. Include the following. As a supply source of molybdenum, ammonium molybdate is preferable. In particular, ammonium molybdate includes a plurality of types of compounds such as ammonium dimolybdate, ammonium tetramolybdate, and ammonium heptamolybdate. Among them, ammonium heptamolybdate is most preferable. As the bismuth component raw material, bismuth nitrate is preferred. As raw materials for iron, cobalt, nickel and other elements, it is usually possible to use oxides, nitrates, carbonates, organic acid salts, hydroxides, etc., which can be converted to oxides by igniting, or mixtures thereof. .

There are no particular limitations on the method for preparing the catalyst of the present invention, but there are roughly two types of preparation methods as described below. For convenience, the methods (A) and (B) are used in the present invention. The method (A) is a method in which the active component of the catalyst is obtained as a powder and then molded, and the method (B) is a method in which a solution in which the active component of the catalyst is dissolved is brought into contact with a preformed carrier. It is a method to carry. Details of the methods (A) and (B) will be described below.

Below, the catalyst preparation method by the (A) method is described. In the following, the order of each step is described as a preferred example, but there is no limitation on the order of each step, the number of steps, and the combination of each step for obtaining the final catalyst product.

Step (A1) Prepare a mixed solution or slurry of the raw material of the preparation and dry catalyst active ingredient, and after passing through steps such as precipitation method, gelation method, coprecipitation method, hydrothermal synthesis method, etc., then dry spray method, evaporation to dryness The dry powder of the present invention is obtained using a known drying method such as a method, a drum drying method or a freeze drying method. In this mixed solution or slurry, any of water, an organic solvent, or a mixed solution thereof may be used as a solvent, and the raw material concentration of the active component of the catalyst is not limited. Furthermore, there are no particular restrictions on the mixing conditions or drying conditions of the mixed solution or slurry, such as the temperature, atmosphere, etc., but it is appropriate in consideration of the final catalyst performance, mechanical strength, moldability, production efficiency, etc. A range should be selected. Among these, the most preferable in the present invention is that a mixed solution or slurry of the raw material of the active component of the catalyst is formed under the condition of 20 ° C. or higher and 90 ° C. or lower, which is introduced into the spray dryer and the dryer outlet is 70 ° C. In this method, the hot air inlet temperature, the pressure inside the spray dryer, and the flow rate of the slurry are adjusted so that the average particle size of the obtained dry powder is 10 μm or more and 700 μm or less.

Step (A2) Pre-baking The dry powder thus obtained can be pre-baked at 200 ° C. or higher and 600 ° C. or lower to obtain the pre-baked powder of the present invention. There are no particular restrictions on the pre-calcination time and the atmosphere during the pre-firing, and the pre-firing method is not particularly limited, such as a fluidized bed, a rotary kiln, a muffle furnace, or a tunnel calcining furnace. An appropriate range should be selected in consideration of performance, mechanical strength, formability, production efficiency, and the like. Among these, in the present invention, the method is preferably performed in a tunnel firing furnace at 300 ° C. or more and 600 ° C. or less, pre-baking 1 hour or more and 12 hours or less in an air atmosphere.

Step (A3) Molding The pre-fired powder obtained in this way can be used as a catalyst as it is, but it can also be molded and used. The shape of the molded product is not particularly limited, such as a spherical shape, a cylindrical shape, or a ring shape, but should be selected in consideration of the mechanical strength, the reactor, the production efficiency of the preparation, etc. finally obtained in a series of preparations. is there. There is no particular limitation on the molding method, but when molding into a cylindrical shape or a ring shape by adding the carrier, molding aid, strength improver, binder, etc. shown in the following paragraph to the pre-fired powder, tableting is performed. When forming into a spherical shape using a machine or an extrusion molding machine, a molded product is obtained using a granulator or the like. Among these, in the present invention, a method in which a pre-fired powder is coated on an inert spherical carrier by a tumbling granulation method and carried out is preferable.

Known materials such as alumina, silica, titania, zirconia, niobia, silica alumina, silicon carbide, carbide, and mixtures thereof can be used as the material for the spherical carrier, and the particle size, water absorption rate, mechanical strength, each crystal There are no particular restrictions on the crystallinity of the phase and the mixing ratio, and an appropriate range should be selected in consideration of the final catalyst performance, moldability, production efficiency, and the like. The loading rate is calculated from the following formula from the charged weight of the spherical carrier and the pre-fired powder.
Support rate (% by weight) = (weight of pre-fired powder used for molding) / {(weight of pre-fired powder used for molding) + (weight of spherical carrier used for molding)} × 100

As raw materials other than the pre-fired powder used for molding, molding aids such as crystalline cellulose or strength improvers such as ceramic whiskers, alcohols, diols, triols and their aqueous solutions as binders are optional. There are no particular restrictions on the type and mixing ratio of the pre-fired powder. In addition, by using the catalyst raw material solution for the binder, it is possible to introduce the element into the outermost surface of the catalyst in a mode different from the step (A1).

Step (A4) Main Firing The pre-fired powder or molded product thus obtained is preferably fired again (main firing) at 300 ° C. or higher and 600 ° C. or lower before being used for the reaction. There is no particular restriction on the firing time and atmosphere during the firing, and the firing method is not particularly limited, such as a fluidized bed, rotary kiln, muffle furnace, tunnel firing furnace, and the final catalyst performance and machine. Appropriate ranges should be selected in consideration of strength and production efficiency. Among these, the most preferable method in the present invention is a method in a tunnel baking furnace in which main baking is performed at 450 ° C. or more and 600 ° C. or less, main baking is performed for 1 hour or more and 12 hours or less in an air atmosphere. At this time, the temperature raising time is usually in the range of 2 hours to 20 hours, preferably 3 hours to 15 hours, and more preferably 4 hours to 10 hours.

Next, the catalyst preparation method by the (B) method is described below. In the following, each step is described in order, but there is no limitation on the order of the steps, the number of steps, and the combination of the steps for obtaining the final catalyst.

Step (B1) A solution or slurry containing the active component of the impregnated catalyst is prepared and impregnated with the shaped carrier or the catalyst obtained by the method (A) to obtain a molded product. Here, the supporting method of the active component of the catalyst by impregnation is not particularly limited, such as a dip method, an incipient wetness method, an ion exchange method, a pH swing method, etc. Water, an organic solvent, or these as a solvent of a solution or slurry Any of the mixed solutions may be used, and the raw material concentration of the active component of the catalyst is not limited. Further, the liquid temperature of the mixed solution or slurry, the pressure applied to the liquid, and the atmosphere around the liquid are not particularly limited. An appropriate range should be selected in consideration of catalyst performance, mechanical strength, moldability, production efficiency, and the like. Further, the shape of the shaped carrier and the catalyst obtained by the method (A) is not particularly limited, such as a spherical shape, a cylindrical shape, a ring shape, and a powder shape, and the material, particle size, water absorption rate, and mechanical strength are not particularly limited. Absent.

Step (B2) Drying The molded product thus obtained is subjected to heat treatment in a range of 20 ° C. to 200 ° C. using a known drying method such as evaporation to dryness, drum drying, freeze drying, etc. The dried catalyst molded body of the invention is obtained. There are no particular restrictions on the drying time and atmosphere during drying, and there are no particular restrictions on the drying method such as fluidized bed, rotary kiln, muffle furnace, tunnel firing furnace, etc. Final catalyst performance, mechanical strength, moldability and production efficiency An appropriate range should be selected in consideration of the above.

Step (B3) Main calcination The catalyst molded dry body thus obtained is heat-treated at a main calcination of 300 ° C. or higher and 600 ° C. or lower to obtain the catalyst of the present invention. Here, there are no particular restrictions on the firing time and atmosphere during firing, and the firing method is not particularly limited, such as fluidized bed, rotary kiln, muffle furnace, tunnel firing furnace, and the final catalyst performance and mechanical strength. An appropriate range should be selected in consideration of moldability and production efficiency. Among these, the most preferable method in the present invention is a method in a tunnel baking furnace in which main baking is performed at 450 ° C. or more and 600 ° C. or less, main baking is performed for 1 hour or more and 12 hours or less in an air atmosphere. At this time, the temperature raising time is usually in the range of 2 hours to 20 hours, preferably 3 hours to 15 hours, and more preferably 4 hours to 10 hours.

The shape and size of the catalyst obtained by the above preparation are not particularly limited, but considering the workability of filling the reaction tube and the pressure loss in the reaction tube after filling, the shape is spherical and the average particle size is The diameter is preferably 3.0 mm or more and 10.0 mm or less, and the catalyst active component loading is preferably 20 wt% or more and 80 wt% or less.

Here, the cumulative specific surface area of the catalyst before being used for the reaction may vary depending on the difference in the composition and shape of the catalyst and the production method, and thus is not particularly limited to express the effect of the present invention. 1.49 ² / g or more and 4.49 ² / g or less, preferably 1.99 ² / g or more and 3.99 ² / g or less, more preferably 2.49 ² / g or more and 3.49 ² / g. .

In the present invention, examples of conditions for subjecting a monoolefin, preferably n-butene, to gas phase catalytic oxidative dehydrogenation in the presence of a catalyst for butadiene production include the following conditions. That is, the raw material gas composition is 1% by volume to 20% by volume n-butene, more preferably 1-butene, 5% by volume to 20% by volume molecular oxygen, 0% by volume to 60% by volume water vapor, A mixed gas containing 0% by volume or more and 94% by volume or less of an inert gas such as nitrogen or carbon dioxide gas is used, the heating medium temperature is in the range of 200 ° C. or more and 500 ° C. or less, and the reaction pressure is normal pressure or more and 10 atm. Under the following pressure, the space velocity (GHSV) of the raw material gas with respect to the catalyst is in the range of 350 hr ⁻¹ or more and 7000 hr ⁻¹ or less. Although there is no restriction | limiting in a fixed bed, a moving bed, and a fluidized bed as a form of reaction, A fixed bed is preferable.

The space velocity in the regeneration step of the catalyst of the present invention (hereinafter abbreviated as GHSV.) Is not particularly limited, usually 50 hr ^-1 or more 4000 hr ^-1 or less, preferably in the range of 100 hr ^-1 or more 2000 hr ^-1 or less. If the GHSV value exceeds the normal range, the catalyst will be damaged and the inside of the reactor will be blocked by the catalyst powder or debris, or it will flow out of the reactor. Contamination due to material spillage can be caused. On the other hand, if the value of GHSV is lower than the normal range, the removal of the coke-like substance may not be performed efficiently, and a long period of time may be required for regeneration, or the effect may not be sufficiently exhibited.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the following, “%” means “mol%” unless otherwise specified. The definitions of 1-butene conversion, butadiene yield, TOS, and breakage rate in the present invention are as follows.

The cumulative specific surface area of the catalyst is measured by the mercury intrusion method. The measured value is calculated from pore distribution data having a pore diameter of 0.0036 μm to 400 μm.

n-butene conversion (mol%)
= (Number of moles of reacted 1-butene / number of moles of 1-butene fed) × 100
Butadiene yield (mol%)
= (Number of moles of butadiene produced / number of moles of n-butene fed) × 100
TOS = Mixed gas circulation time (hours)
The failure rate was determined by extracting the catalyst from the reaction tube after regeneration and classifying it with a 3.35 mm sieve, and weighed the catalyst that had broken down into a piece and powder that fell under the sieve as a catalyst piece. Calculated by the formula.
Damage rate (% by weight)
= Weight of catalyst piece (g) / weight of catalyst extracted after reaction (g) x 100

Example 1
(Preparation of catalyst)
800 parts by weight of ammonium heptamolybdate was completely dissolved in 3000 parts by weight of pure water heated to 80 ° C. (Mother solution 1). Next, 11 parts by weight of cesium nitrate was dissolved in 124 ml of pure water and added to the mother liquor 1. Next, 275 parts by weight of ferric nitrate, 769 parts by weight of cobalt nitrate, and 110 parts by weight of nickel nitrate were dissolved in 612 ml of pure water heated to 60 ° C. and added to the mother liquor 1. Subsequently, 311 parts by weight of bismuth nitrate was dissolved in a nitric acid aqueous solution prepared by adding 79 parts by weight of nitric acid (60% by weight) to 330 ml of pure water heated to 60 ° C. and added to the mother liquor 1. This mother liquor 1 was dried by a spray drying method, and the obtained dry powder was pre-fired at 440 ° C. for 5 hours. After adding 5% by weight of crystalline cellulose to the pre-fired powder obtained in this manner and mixing well, an inert spherical carrier using a 33% by weight glycerin solution as a binder by tumbling granulation method (Silica alumina) was molded into a spherical shape so that the loading ratio was 50% by weight. The spherical molded product thus obtained was calcined at 520 ° C. for 5 hours to obtain the catalyst of the present invention. The atomic ratio of the catalyst calculated from the charged raw materials was Mo: Bi: Fe: Co: Ni: Cs = 12: 1.7: 1.8: 7.0: 1.0: 0.15. Here, the cumulative specific surface area of the catalyst before being used in the reaction was measured and found to be 2.99 m ² / g.

(Reaction test)
The obtained catalyst (53 ml) was charged into a stainless steel reaction tube, and a mixed gas having a gas volume ratio of 1-butene: oxygen: nitrogen: water vapor = 1: 1: 7: 1 was used under the conditions of GHSV 1200 hr ⁻¹ under normal pressure. Then, the temperature of the heat medium circulating in the reactor was changed so that the 1-butene conversion rate = 78.0 ± 1.0% could be maintained, and the reaction was continued up to 400 hours of TOS. Thereafter, the supply of 1-butene, oxygen, and water vapor is stopped, and the heat medium circulating in the reactor is lowered to 220 ° C. for the purpose of regeneration to remove the deposited coke-like substance, and then air is used under atmospheric pressure, space The combustion reaction was started at a rate of 250 hr ⁻¹ , and the temperature was raised stepwise until the heat medium reached 400 ° C. in an air atmosphere. It was 3.78 m < ² > / g when the catalyst after reproduction | regeneration was extracted and the cumulative specific surface area was measured. Further, the damage rate was measured and found to be 0.05% by weight.

Example 2
(Reaction test)
A stainless steel reaction tube was charged with 53 ml of the catalyst obtained in Example 1, and a gas mixture with a gas volume ratio of 1-butene: oxygen: nitrogen: water vapor = 1: 1: 7: 1 was used and GHSV 1200 hr ⁻ under normal pressure. ^Under the conditions of 1, the temperature of the heating medium circulating in the reactor was changed so that 1-butene conversion rate = 97.0 ± 1.0% could be maintained, and the reaction was continued up to 600 hours of TOS. The butadiene yield at that time was 85.4%. In the middle of the reaction, the supply of 1-butene and additional nitrogen gas was stopped, and regeneration was carried out four times alternately with the reaction by raising the temperature of the heating medium to 400 ° C. while circulating only air. The cumulative specific surface area of the catalyst extracted after the last regeneration was measured and found to be 3.15 m ² / g. Moreover, it was 0.02 weight% when the failure rate was measured. Thereafter, when the reaction was resumed so as to maintain 1-butene conversion = 97.0 ± 1.0%, the butadiene yield was 85.8%.

Example 3
(Reaction test)
1.64 L of the catalyst obtained in Example 1 was charged into a stainless steel reaction tube, and a gas mixture having a gas volume ratio of 1-butene: oxygen: nitrogen: water vapor = 1: 1.2: 11.1: 2.3 Was used, and the temperature of the heating medium circulating in the reactor was changed so as to maintain 1-butene conversion = 92.0 ± 1.0% under normal pressure and GHSV 2000 hr ⁻¹ , and the reaction was continued up to 4000 hours of TOS. In the middle of the reaction, the supply of 1-butene, additional nitrogen gas, and water vapor was stopped, and regeneration in which the temperature of the heating medium was raised to 400 ° C. while circulating only air was performed twice alternately with the reaction. The cumulative specific surface area of the gas inlet portion of the catalyst extracted after the last regeneration was measured and found to be 2.90 m ² / g. Moreover, it was 0.03 weight% when the breakage rate was measured.

Comparative Example 1
(Reaction test)
The cumulative specific surface area of the gas outlet portion of the catalyst extracted after the last regeneration in Example 3 was 5.18 m ² / g. Moreover, when the failure rate was measured, it was 1.95% by weight, and the failure of the catalyst was visually observed.

As in the examples, the post-regeneration catalyst with a cumulative specific surface area of 5.17 m ² / g or less tends to have a low failure rate, and the yield in the reaction after the regeneration can be maintained. It can be seen that the catalyst has excellent long-term stability that can withstand continuous use. Further, in the comparative example, the cumulative specific surface area exceeds 5.17 m ² / g and the failure rate tends to be high, so that the damage is progressing even when the catalyst is regenerated, the reaction tube is blocked, the occurrence of an abnormal reaction, etc. It can be seen that this is a state that can induce various troubles.

Claims

A method for producing a conjugated diolefin by subjecting a monoolefin having 4 or more carbon atoms to gas phase catalytic oxidative dehydrogenation in the presence of a catalyst for producing a conjugated diolefin, wherein the active component composition of the catalyst before use is as follows: A method for producing a conjugated diolefin, wherein the catalyst represented by the formula 1 is regenerated after use, and the regenerated catalyst having a cumulative specific surface area of 5.17 m 2 / g or less is used,
Mo 12 Bi a Fe b Co c Ni d X e Y f Z g O h ···· ( Equation 1)
(In the formula, X represents at least one element of an alkali metal selected from lithium, sodium, potassium, rubidium, and cesium, and Y represents at least one element of an alkaline earth metal selected from magnesium, calcium, strontium, and barium. Z represents an element, and Z represents at least one element selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, antimony, tungsten, lead, zinc, cerium, thallium, and a, b, c, d, e, f and g each represent an atomic ratio of each component to molybdenum 12, and 0.2 ≦ a ≦ 2.0, 0.6 <b <3.4, 5.0 <c <8.0, 0 <d < 3.0, 0 <e <0.5, 0 ≦ f ≦ 4.0, 0 ≦ g ≦ 2.0, and h is a numerical value that satisfies the oxidation state of other elements).
The catalyst is a shaped catalyst in which a carrier is coated with a catalytically active component. The resulting shaped catalyst has an average particle size of 3.0 mm or more and 10.0 mm or less, and a loading ratio of the catalyst active component is 20 wt% or more and 80 wt% The manufacturing method according to claim 1, which is not more than%.
The production method according to claim 1 or 2, wherein the monoolefin having 4 or more carbon atoms is n-butene and the conjugated diolefin is 1,3-butadiene.