JP2010229056A - Method for producing olefin dimer, and olefin dimer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an olefin dimer using a solid phosphate catalyst. <P>SOLUTION: This method for producing the olefin dimer is characterized by comprising a first process for introducing the first mixture comprising an olefin in an amount of 0 to 15 mass% based on the total amount of the mixture, water in an amount below a saturated water content in a contact condition and equal to or above 10 mass ppm, and a prescribed solvent, into a reactor receiving a solid phosphate catalyst prepared by supporting phosphoric acid on inorganic support particles, and then heating and pressurizing the mixture to give a prescribed contact condition in the reactor, in the contact state of the solid phosphate catalyst with the first mixture; and a second process for introducing the second mixture comprising the olefin, and water in an amount below the saturated water content at a reaction temperature and equal to or larger than 10 mass ppm, into the reactor after the first process, and subjecting to an olefin-dimerizing reaction in the presence of the solid phosphate catalyst at a reaction temperature of 55 to 300°C to obtain the reaction product containing the olefin dimer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an olefin dimer using a solid phosphoric acid catalyst and an olefin dimer obtained by the method.

  The solid phosphoric acid catalyst is a catalyst in which phosphoric acid is supported on an inorganic carrier, and is widely used for olefin hydration reaction, olefin oligomerization reaction, and the like.

  On the other hand, oligomers of olefins are used in various applications. In particular, dimers of light olefins (for example, propylene, normal butene, isobutene, and pentenes) are important as high octane base materials and chemical intermediate materials for gasoline. . Oligomerization including dimerization of olefins is carried out using an acid catalyst, and many studies have been made so far. Examples of acid catalysts include sulfuric acid, hydrofluoric acid, phosphoric acid, aluminum chloride, boron fluoride and other liquid or gas catalysts, amorphous or crystalline aluminosilicates, clays, ion exchange resins, composite oxides, carriers Various solid acids such as acids supported on the catalyst are listed as conventional examples, and various studies have been made on the above-described solid phosphoric acid catalyst that can be produced at a low cost with a simple manufacturing process.

  As an example of an olefin oligomerization reaction using a solid phosphoric acid catalyst, for example, a method of oligomerizing propylene using a solid phosphoric acid catalyst prepared under calcination conditions exceeding 100 ° C. (see, for example, Patent Document 1 below). Or a catalyst prepared by treating and crystallizing an amorphous mixture of phosphoric acid and siliceous raw material under conditions of 250 to 450 ° C. in an air-water vapor mixed gas atmosphere having a water vapor concentration of 3 to 50 mol% (silicon ortho A method of oligomerizing propylene using a catalyst comprising a phosphate and silicon pyrophosphate (see, for example, Patent Document 2 below) has been proposed. In addition, it has been conventionally known that the degree of condensation of phosphoric acid of a solid phosphoric acid catalyst affects the activity of the olefin oligomerization reaction. For example, Patent Document 3 and Non-Patent Document 1 listed below describe solid phosphoric acid. A catalyst with a small weight ratio of the free phosphoric acid component (non-condensed or low-condensed phosphoric acid such as orthophosphoric acid, pyrophosphoric acid, etc.) eluted by immersing the catalyst in water to the catalyst (ratio of orthophosphoric acid in the supported phosphoric acid) However, an example in which an olefin such as C3 and C4 is oligomerized using at most 46 mol% in terms of phosphorus atom is disclosed.

  However, none of the above-mentioned oligomerization of olefins using the conventional solid phosphoric acid catalyst is aimed at dimerization of olefins. In addition, conventional solid phosphoric acid catalysts are a by-product of high-polymerization of olefins. However, it was difficult to selectively obtain an olefin dimer.

  There is an example in which the improvement of dimerization selectivity of olefins has been studied. For example, in Patent Document 4 below, the ratio of orthophosphoric acid in phosphoric acid supported on a carrier is 60 mol% or more in terms of phosphorus atom An olefin dimerization method using a phosphoric acid catalyst has been proposed.

  On the other hand, in the oligomerization reaction of olefin using a solid phosphoric acid catalyst, the reaction liquid obtained from the reactor outlet contains phosphoric acid eluted from the catalyst, and before the supply of the olefin-containing raw material at the start of the oligomerization reaction However, there is no description that the elution of phosphoric acid from the solid phosphoric acid catalyst can be reduced by contacting with a medium containing no olefin or containing an olefin having a specific concentration or less and containing a specific concentration of water. Further, there is no description that the elution of phosphoric acid can be reduced by selecting the temperature of the oligomerization reaction.

  The phosphoric acid eluted in the reaction solution corrodes the equipment because phosphoric acid is concentrated when the LPG fraction and oligomer, or oligomer and heavy material are separated in a distillation column downstream of the oligomerization reaction process. sell. Therefore, it is desirable to suppress elution of phosphoric acid into the reaction solution.

Japanese Patent Publication No. 8-29251 Japanese Patent Publication No. 7-59301 JP 2001-199907 A JP 2006-51492 A JP 9-233290 A

“Applied Catalysis A: General”, 1993, 97, p.177-196

  When dimerizing an olefin using a solid phosphoric acid catalyst, the present inventors have found that a very small amount of phosphoric acid (including one that becomes phosphoric acid by hydrolysis) elutes from the catalyst into the reaction solution. Since this trace amount of phosphoric acid causes corrosion of the apparatus, removal of a trace amount of phosphoric acid in the reaction solution is an important issue. In order to efficiently produce an olefin dimer, not only the catalytic activity of the solid phosphoric acid catalyst and the dimerization selectivity of the olefin are improved, but also the phosphoric acid is prevented from eluting into the hydrocarbon solution. desirable. However, although Patent Document 4 describes the relationship between the phosphoric acid composition of the solid phosphoric acid catalyst and the dimerization selectivity, there is no disclosure about suppression of phosphoric acid elution into the reaction solution.

  Thus, the present invention provides a method for producing an olefin dimer with high selectivity using a solid phosphoric acid catalyst, and elutes into a reaction solution when such a solid phosphoric acid catalyst is used. It aims at providing the manufacturing method of the olefin dimer which suppresses phosphoric acid and makes it possible to produce an olefin dimer efficiently, and the olefin dimer obtained by the manufacturing method.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, in the dimerization reaction of an olefin using a solid phosphoric acid catalyst supported on inorganic support particles, the reaction is performed at a specific temperature condition. It was found that phosphoric acid and by-product oxygen-containing compounds that were eluted could be efficiently removed by controlling the elution of phosphoric acid into the reaction product and washing the reaction product under specific conditions. That is, by setting the olefin dimerization reaction temperature to 55 ° C. or higher, the amount of phosphoric acid eluted in the reaction solution is kept low, and then the phosphoric acid eluted in the reaction solution is alkali washed at a specific pH and temperature range, Thereafter, by washing with water in a specific temperature range, the inventor has obtained knowledge that by-products such as phosphoric acid and oxygen-containing compounds that have been eluted can be efficiently removed, and the present invention has been completed.

That is, this invention provides the manufacturing method of the olefin dimer as described in following (1)-(8), and the olefin dimer as described in following (9).
(1) In a reactor containing a solid phosphoric acid catalyst in which phosphoric acid is supported on inorganic support particles, 0 to 15% by mass of olefin, based on the total amount of the mixture, and less than 10% by mass of saturated water under contact conditions A first mixture containing ppm or more of water and a predetermined medium is introduced, and the temperature inside the reactor is increased to a predetermined contact condition while the solid phosphoric acid catalyst and the first mixture are in contact with each other. Into the reactor after the first step of increasing the pressure and the reactor after the first step, the second mixture containing olefin and water of less than the saturated water content at the reaction temperature and 10 mass ppm or more is introduced, and the solid And a second step of performing a dimerization reaction of the olefin at a reaction temperature of 55 to 300 ° C. in the presence of a phosphoric acid catalyst to obtain a reaction product containing the olefin dimer. Body manufacturing method.
(2) The production according to (1), further comprising a third step of supporting and regenerating phosphoric acid on the solid phosphoric acid catalyst after the second step, and subjecting it to the first step. Method.
(3) The temperature at which phosphoric acid is supported on the solid phosphoric acid catalyst in the third step is 100 ° C. or lower, and the phosphoric acid concentration used for supporting is 93% by mass or less as normal phosphoric acid. (2) The manufacturing method according to (2).
(4) The production method according to any one of (1) to (3), wherein the medium is a liquid hydrocarbon.
(5) The ratio of orthophosphoric acid in phosphoric acid of the solid phosphoric acid catalyst used in the first step is 60 mol% or more in terms of phosphorus atoms, and the pore diameter is 15 to 200 nm. The manufacturing method in any one of (1)-(4).
(6) The method according to any one of (1) to (5), wherein the particle size of the inorganic carrier of the solid phosphoric acid catalyst used in the first step is 3.0 mm or less. .
(7) The production method according to any one of (1) to (6), wherein the dimerization reaction in the second step is performed in a liquid phase.
(8) The production method according to any one of (1) to (7), wherein the olefin is a monoolefin having 3 to 7 carbon atoms.
(9) An olefin dimer obtained by the production method according to any one of (1) to (8).

  According to the present invention, in the dimerization reaction of an olefin using a solid phosphoric acid catalyst, the solid phosphoric acid is pretreated under specific conditions before starting the dimerization reaction, and the reaction is performed by selecting specific dimerization reaction conditions. It is possible to provide a method capable of reducing phosphoric acid eluted into the liquid. It also enables efficient olefin dimer production.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

The manufacturing method of the olefin dimer of this invention comprises the process shown to following (I) and (II).
(I) In a reactor containing a solid phosphoric acid catalyst in which phosphoric acid is supported on inorganic carrier particles, 0 to 15% by mass of olefin based on the total amount of the mixture, and less than 10% by mass of saturated water under contact conditions A first mixture containing ppm or more of water and a predetermined medium is introduced, and the temperature inside the reactor is increased to a predetermined contact condition while the solid phosphoric acid catalyst and the first mixture are in contact with each other. , A reaction preparation step of increasing pressure.
(II) The presence of a solid phosphoric acid catalyst is introduced into the reactor after step (I) by introducing a second mixture containing olefin and water of less than the saturated water content at the reaction temperature and 10 ppm by mass or more. Below, the dimerization process which performs the dimerization reaction of an olefin at the reaction temperature of 55-300 degreeC, and obtains the reaction product containing an olefin dimer.
Moreover, it is preferable that the manufacturing method of the olefin dimer of this invention further includes the process shown to following (III).
(III) A catalyst regeneration step in which phosphoric acid is supported on the solid phosphoric acid catalyst after the step (II) and regenerated, and used for the step (I).

  Hereinafter, each process of (I)-(III) is explained in full detail.

<(I) Reaction preparation step>
The solid phosphoric acid catalyst used in the present invention is particularly limited as long as it has an activity of dimerizing olefins and contains phosphoric acid (including those that become phosphoric acid by hydrolysis) as a catalyst component. It is not something.

  The inorganic carrier particles constituting the solid phosphoric acid catalyst are not particularly limited as long as they can support phosphoric acid, but preferred examples include diatomaceous earth, dripworm earth, ciliate earth, kieselguhr, kaolin, fuller earth, artificial Mention may be made of formed particles of siliceous carriers such as porous silica and mixtures thereof. In the case of forming the carrier, calcination can be performed under any temperature condition for the purpose of providing sufficient strength, pore volume, and specific surface area. The molding method and the shape of the molded body are not particularly limited, and various moldings such as tableting, extrusion molding, spray drying, tumbling granulation, and in-oil granulation can be used. It can be a body particle. Moreover, the solid phosphoric acid catalyst deactivated by the reaction after the step (III) can also be used.

  The preferable average pore diameter of the inorganic carrier particles used in this step is 15 to 200 nm, more preferably 30 to 200 nm, and still more preferably 30 to 100 nm. When the average pore diameter is less than 15 nm, the diffusion resistance of the substance existing in the pores to the outside of the pores increases, so that the olefin dimer generated by the catalytic action of phosphoric acid in the pores is longer. It remains in the pores for a long time, and the olefin dimer is further easily converted into a heavy product of trimer or higher by the catalytic action of phosphoric acid. This tends to reduce the dimerization selectivity. When the average pore diameter exceeds 200 nm, it becomes difficult to achieve both the mechanical strength of the catalyst and the catalytic activity. For example, when the inorganic carrier particles include silicon dioxide, even if the average pore diameter exceeds 200 nm, the density of the silicon dioxide structure can be increased to reduce the crushing strength by reducing the pore volume. Although it can be increased, if the pore volume is small, the amount of phosphoric acid supported in the pores is reduced, which causes a problem that the reaction activity per unit volume of the catalyst layer is lowered. If the average pore diameter exceeds 200 nm and an attempt is made to secure the pore volume, the density of the silicon dioxide structure in the carrier becomes small, which causes a problem that the crushing strength of the carrier is lowered.

  In the present invention, the average pore diameter of the inorganic carrier particles is measured using a mercury intrusion method suitable for this because the average pore diameter of the inorganic carrier particles used is 15 nm or more. For example, it can be measured using an automatic porosimeter “Micromeritics Autopore II” (trade name) manufactured by Shimadzu Corporation.

  The preferable average particle diameter of the inorganic carrier particles used in this step is 3.0 mm or less, preferably 0.5 to 3.0 mm. When the average particle diameter is less than 0.5 mm, the pressure loss of the reactor increases, which is not preferable. In the case of 3.0 mm or more, the amount of the reaction fluid flowing through the tube wall in the reactor increases, so that the catalyst is not effectively used and the dimerization reaction activity tends to decrease. In addition, since it takes a longer time for the substance present in the center of the catalyst particle to diffuse out of the catalyst particle, the olefin dimer generated by the catalytic action of phosphoric acid in the center of the catalyst particle will remain in the catalyst particle for a longer time. The olefin dimer is more easily converted into a heavy product of trimer or higher by the catalytic action of phosphoric acid. This tends to reduce the dimerization selectivity.

  The average particle diameter of the inorganic carrier particles is obtained by measuring the diameter of each particle randomly extracted from the inorganic carrier particles and arithmetically averaging the diameters of 25 carrier particles.

  Next, the phosphoric acid which comprises the solid phosphoric acid catalyst of this invention is demonstrated.

  The phosphoric acid used in the present invention preferably has a ratio of orthophosphoric acid in phosphoric acid of 60 mol% or more in terms of phosphorus atoms. That is, the phosphoric acid supported on the inorganic carrier particles is such that the ratio of phosphorus atoms in orthophosphoric acid to the number of moles of all phosphorus atoms contained in phosphoric acid is 60 mol% or more. In this case, excellent activity and selectivity for the dimerization reaction of olefin are expressed. The ratio is more preferably 70 mol% or more, and even more preferably 80 mol% or more. In order to maintain high activity and selectivity in the olefin dimerization reaction for a long period of time, the ratio of orthophosphoric acid in the supported phosphoric acid to other condensed polyphosphoric acid is important. It is preferable to contact the olefin in a state where the ratio of orthophosphoric acid is 60 mol% or more.

  Examples of the phosphoric acid used in preparing the solid phosphoric acid catalyst of the present invention include orthophosphoric acid and its condensate, pyrophosphoric acid and polyphosphoric acid, but those which become phosphoric acid by hydrolysis (phosphoric acid precursor) For example, a phosphate ester of an alcohol having 1 to 8 carbon atoms can also be used. Moreover, those mixtures may be sufficient. The phosphoric acid concentration used for immersion is preferably 93% by mass or less in terms of normal phosphoric acid. More preferably, it is 30 to 85%. When the phosphoric acid concentration is 93% or more, it is difficult to make the ratio of orthophosphoric acid out of phosphoric acid in the solid phosphoric acid catalyst after loading 60 mol% or more. On the other hand, if it is 30% or less, the amount of phosphoric acid contained in the solid phosphoric acid catalyst after loading decreases, such being undesirable.

The method for supporting phosphoric acid on the inorganic carrier particles was obtained by immersing the inorganic carrier particles or the deactivated solid phosphoric acid catalyst in an aqueous phosphoric acid solution and then drying, or by mixing the inorganic carrier and the aqueous phosphoric acid solution. A method of forming and drying a paste is generally used. In the former method, when phosphoric acid in the catalyst is dissolved in the reaction solution during the dimerization reaction and the amount of phosphoric acid supported decreases, the phosphoric acid can be replenished as appropriate by re-impregnation of the catalyst. preferable. In the case of the latter method, the molding method and the shape of the molded product can be performed in the same manner as the molding of the inorganic carrier particles.

  The content of phosphoric acid in the solid phosphoric acid catalyst is not particularly limited, but orthophosphoric acid is used as a proportion of the mass of the solid phosphoric acid catalyst prepared by supporting phosphoric acid on the inorganic carrier particles contained in the inorganic carrier particles. 15-75 mass% is preferable in conversion. When this ratio is less than 15% by mass, the activity becomes low or the required catalyst capacity tends to increase, and the equipment cost tends to increase. Moreover, when it exceeds 75 mass%, it is not preferable because it becomes difficult to make the ratio of orthophosphoric acid to the total phosphoric acid 60 mol% or more.

  As an example of a specific embodiment of catalyst preparation, a method for supporting inorganic particles by drying them after immersing them in an aqueous phosphoric acid solution will be described. There is no particular limitation on the apparatus used for catalyst preparation, and a general batch tank can be used. However, the method using a reactor for carrying out dimerization reaction of olefins in a stationary phase flow type is a catalyst simultaneously with catalyst preparation. This is a preferred method because it can be filled. The immersion time is not particularly limited as long as it is usually about 1 hour or longer. The preferable immersion temperature is 100 ° C. or lower, more preferably 50 ° C. or lower. Temperature conditions exceeding 100 ° C. are not preferable because the ratio of orthophosphoric acid in phosphoric acid may be small. Further, if the temperature is too low, it is solidified and cannot be impregnated, so 0 ° C. or higher, more preferably 15 ° C. or higher. In addition, it is preferable that the number of immersions is twice or more because unevenness in support is less likely to occur.

  After the immersion, the residue of the phosphoric acid aqueous solution is removed by a general method such as filtration, and then the remaining excess water is removed and dried. As a drying method, a gas flow or a liquid flow may be used. Although the fluid used for drying is not specifically limited, Air, nitrogen gas, hydrogen gas, a C1-C5 saturated hydrocarbon gas, and a C2-C20 saturated hydrocarbon liquid are suitable. Further, the fluid may contain water not exceeding the saturation amount in the drying conditions. For example, drying can be performed using liquid butane containing 100 ppm by mass or less of water at room temperature. A preferable drying temperature is 100 ° C. or lower, more preferably 50 ° C. or lower. A temperature exceeding 100 ° C. is not preferable because condensation of phosphoric acid occurs rapidly and the ratio of orthophosphoric acid in phosphoric acid decreases. Moreover, since drying efficiency will worsen if temperature is too low, 0 degreeC or more, Furthermore 5 degreeC or more is preferable. The drying time and the amount of fluid used are appropriately adjusted so that the proportion of orthophosphoric acid in phosphoric acid does not become less than 60 mol% in terms of phosphorus atoms while confirming the progress of condensation of phosphoric acid by drying. The highly condensed phosphoric acid catalyst in which condensation of phosphoric acid has progressed can be returned to a low condensed state (state in which the ratio of orthophosphoric acid is 60 mol% or more) by reimpregnation treatment.

  In the olefin dimerization reaction, the water content in the solid phosphoric acid catalyst is preferably 5% by mass or more based on the mass of the solid phosphoric acid catalyst.

  Next, the first mixture (mixture containing 0 to 15% by mass of olefin based on the total amount of the mixture, less than the saturated water content and 10 ppm by mass or more of water in the contact condition, and a predetermined medium) will be described. In this step, by using the first mixture, phosphoric acid eluted from the solid phosphoric acid catalyst in the reaction solution in the dimerization reaction can be significantly suppressed, and corrosion due to phosphoric acid in the latter stage of the process can be avoided. Since phosphoric acid is highly corrosive, inexpensive steel materials such as carbon steel are easily corroded under conditions exceeding 100 ° C. Although corrosion can be suppressed by lining the apparatus with a corrosion-resistant material such as Hastelloy or tantalum, these corrosion-resistant materials are extremely expensive. If the elution of phosphoric acid is reduced, it is not necessary to use such an expensive material, and the economic effect is great. The phosphoric acid elution suppression method described above is a very simple operation of selecting specific operating conditions, and thus contributes to an improvement in economic efficiency. Moreover, since elution of phosphoric acid can be suppressed, it contributes to extending the life of the solid phosphoric acid catalyst. There is no restriction | limiting in particular as a supply method of a water | moisture content.

  The medium contained in the first mixture is preferably a linear, branched, or cyclic hydrocarbon having 1 to 7 carbon atoms, and these may be a single hydrocarbon or any two or more of them. Combinations can also be used. The state of the medium may be gaseous or liquid, but the liquid is less likely to cause drying unevenness in the solid phosphoric acid catalyst, and the orthophosphoric acid in the catalyst phosphoric acid is more likely to be maintained at 60 mol% or more. Therefore, it is preferable. In addition, as a medium used for this process, inorganic gas, such as nitrogen, argon, and hydrogen, can also be used.

  The first mixture includes both an embodiment in which the olefin content is 0% by mass (that is, an olefin-free product) and an embodiment in which the olefin content is more than 0% by mass and 15% by mass or less based on the total amount of the mixture. included. When the first mixture contains an olefin, the olefin is preferably a linear, branched or cyclic monoolefin having 3 to 5 carbon atoms. Further, it may be a single olefin or a mixture of two or more olefins depending on the target product. Specific olefins include propylene, 1-butene, cis-2-butene, trans-2-butene, isobutylene, normal pentenes, isopentenes, cyclopentenes, and combinations of any two or more thereof. it can. As described above, a hydrocarbon medium containing no olefin can be used.

  The temperature increase and pressure increase rate in this step can be arbitrarily selected. For example, it is preferable to raise the temperature to 55 to 300 ° C. at a temperature rising rate of 0.2 to 5 ° C./min. Moreover, it is preferable to hold | maintain at the same temperature for 1 to 170 hours after reaching the said temperature.

<(II) Dimerization reaction step>
In this reactor after the first step, this step is a second mixture containing olefin and water of less than the saturated water content at the reaction temperature and 10 ppm by mass or more (hereinafter referred to as “olefin-containing raw material”). And a dimerization reaction of olefin at a reaction temperature of 55 to 300 ° C. in the presence of a solid phosphoric acid catalyst to obtain a reaction product containing an olefin dimer. The dimerization of olefin means that 1 mol of olefin is generated by reaction of 2 mol of raw material olefin (including reaction between different olefins in the case of olefin mixed raw material).

  In this step, the content of water contained in the raw material mixture is adjusted to be 10 mass ppm or more based on the total amount of the olefin-containing raw material and less than the saturated water content of the raw material at the reaction temperature. Thereby, it can suppress that the condensation of the phosphoric acid in a catalyst progresses gradually with progress of reaction, and can fully raise the yield of an olefin dimer. The amount of water in the olefin-containing raw material can be adjusted by allowing water to coexist in the reaction system. There is no restriction | limiting in particular as a supply method of a water | moisture content, The method etc. which dissolve a predetermined amount of water in an olefin containing raw material with a mixing apparatus, and supply to a reactor are mentioned. The water content in the olefin-containing raw material is preferably less than the saturated water content of the olefin-containing raw material at the reactor inlet temperature, but it is necessary to select the optimum addition amount according to the reaction conditions such as the raw material concentration and reaction temperature. There is. When the amount of water added is equal to or greater than the saturated water amount, the condensed water causes the phosphoric acid on the catalyst to flow out, which is not preferable. In addition, from the viewpoint of reliably suppressing the condensation of phosphoric acid, the water content in the olefin-containing raw material is 100 mass ppm or more based on the mass of the raw material and less than the saturated water content of the raw material olefin at the temperature in the reactor. Is desirable.

There are no particular limitations on the reactor and reaction format used in this step, and batch, semi-batch, and continuous flow reaction formats using a tank reactor, for example, continuous using a flow reactor such as a fixed bed, fluidized bed, and moving bed. A flow reaction or the like can be employed. The reaction temperature is 55 to 300 ° C, preferably 55 to 200 ° C. A temperature lower than 55 ° C. is not preferable because elution of phosphoric acid is remarkably increased. Further, a temperature higher than 300 ° C. is not preferable because side reactions such as a decomposition reaction and a polymerization reaction accompanying the reaction increase. The reaction pressure is preferably from normal pressure to 20 MPa, and if it is less than normal pressure, the reaction system may not be able to maintain a liquid phase, and if it exceeds 20 MPa, the equipment cost increases, which is not preferable. The reaction time in the reaction form of continuous flow, as LHSV, 0.1~100hr ^-1, preferably 0.3~30hr ^-1. When LHSV is less than 0.1 hr ⁻¹ , production efficiency is reduced or the equipment becomes huge, and when it exceeds 100 hr ⁻¹ , the reaction is difficult to proceed. On the other hand, in the case of a batch-type reaction system, the preferred reaction time is 0.01 to 10 hours, although it varies depending on the olefin concentration in the raw material, the raw material / catalyst ratio, and the like.

  In this step, the olefin contained in the olefin-containing raw material is preferably a linear, branched or cyclic monoolefin having 3 to 5 carbon atoms. Further, it may be a single olefin or a mixture of two or more olefins depending on the target product. Specific olefins include propylene, 1-butene, cis-2-butene, trans-2-butene, isobutylene, normal pentenes, isopentenes, cyclopentenes, and combinations of any two or more thereof. it can.

  Moreover, the olefin containing raw material containing a solvent can be used in order to remove reaction heat. The solvent is not particularly limited as long as it is liquid under the dimerization reaction conditions and is essentially inert to the solid phosphoric acid catalyst. For example, hydrocarbons such as normal paraffin, isoparaffin, naphthenes, and aromatics can be preferably used. In addition, saturated hydrocarbons such as butanes in paraffin fractions and C4 fractions containing olefins having a lower concentration than the raw material recovered as unreacted components after the dimerization reaction step can also be used as the solvent. As a ratio of the amount of olefin and the amount of solvent, the proportion of olefin in the total mass of the olefin-containing raw material containing olefin and solvent is 1 to 60% by mass, preferably 10 to 50% by mass, more preferably 15 to 45% by mass. It is desirable that When the ratio of the olefin is below the lower limit, the productivity is lowered, and when it exceeds the upper limit, the calorific value of the dimerization reaction is increased, and the reaction temperature is difficult to control.

  In this step, the olefin-containing raw material is brought into contact with the solid phosphoric acid catalyst in a liquid phase. The contact in the gas phase is not preferable because the activity and selectivity of the dimerization reaction of the olefin may be reduced due to the occurrence of coking, and the catalyst life may be shortened.

<(III) Catalyst regeneration step>
This step is a step of regenerating the solid phosphoric acid catalyst by carrying phosphoric acid on the solid phosphoric acid catalyst deactivated by the reaction after step (II).

  The preferable average pore diameter of the deactivated solid phosphoric acid catalyst used in this step is 15 to 200 nm, more preferably 30 to 200 nm, and still more preferably 30 to 100 nm. When the average pore diameter is less than 15 nm, the diffusion resistance of the substance existing in the pores to the outside of the pores increases, so that the olefin dimer generated by the catalytic action of phosphoric acid in the pores is longer. It stays in the pores for a long time, and the olefin dimer is more easily converted into a heavy product of trimer or higher by the catalytic action of phosphoric acid. This tends to reduce the dimerization selectivity. When the average pore diameter exceeds 200 nm, it becomes difficult to achieve both the mechanical strength of the catalyst and the catalytic activity. For example, when the inorganic carrier particles include silicon dioxide, even if the average pore diameter exceeds 200 nm, the density of the silicon dioxide structure can be increased to reduce the crushing strength by reducing the pore volume. Although it can be increased, if the pore volume is small, the amount of phosphoric acid supported in the pores is reduced, which causes a problem that the reaction activity per unit volume of the catalyst layer is lowered. If the average pore diameter exceeds 200 nm and an attempt is made to secure the pore volume, the density of the silicon dioxide structure in the carrier becomes small, which causes a problem that the crushing strength of the carrier is lowered.

  In the present invention, the average pore size of the deactivated solid phosphoric acid catalyst is the same as in the case of measuring the average pore size of the inorganic carrier particles. It can be measured by the mercury intrusion method.

  The preferable average particle diameter of the inorganic carrier particles or the deactivated solid phosphoric acid catalyst used in this step is 3.0 mm or less, preferably 0.5 to 3.0 mm. When the average particle diameter is less than 0.5 mm, the pressure loss of the reactor increases, which is not preferable. In the case of 3.0 mm or more, the amount of the reaction fluid flowing through the tube wall in the reactor increases, so that the catalyst is not effectively used and the dimerization reaction activity tends to decrease. In addition, since it takes a longer time for the substance present in the center of the catalyst particle to diffuse out of the catalyst particle, the olefin dimer generated by the catalytic action of phosphoric acid in the center of the catalyst particle will remain in the catalyst particle for a longer time. The olefin dimer is more easily converted into a heavy product of trimer or higher by the catalytic action of phosphoric acid. This tends to reduce the dimerization selectivity.

  The average particle diameter of the deactivated solid phosphoric acid catalyst was measured by measuring the diameter of each particle randomly extracted from the deactivated solid phosphoric acid catalyst, and the diameter of 25 deactivated solid phosphoric acid catalysts was added. Calculate by averaging.

  In this step, the type of phosphoric acid, the ratio of orthophosphoric acid in phosphoric acid, the loading method, the content of phosphoric acid in the solid phosphoric acid catalyst after regeneration, the amount of water in the solid phosphoric acid catalyst, etc. I) It is the same as in the case of the reaction preparation step, and redundant explanation is omitted here.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to a following example.

Example 1
After loading 20 ml of a silica granulated product having an average pore diameter of 50 nm and an average particle diameter of 2.3 mm as a carrier into a tubular stainless steel reactor (inner diameter 12 mm), 40 mass% in terms of orthophosphoric acid. The carrier was immersed in phosphoric acid by feeding 50 ml of the phosphoric acid aqueous solution from above into the reactor with a pump. After immersion for 24 hours, the lower part of the reactor was opened and the phosphoric acid aqueous solution was removed by its own weight. This operation was repeated twice to prepare a solid phosphoric acid catalyst A (Step 1). While feeding hexane containing 30 mass ppm of water to this catalyst A from the top of the reactor at 50 ml / h, after 2 hours, a pressure of 3.0 Mpa and a catalyst layer inlet temperature of 90 ° C. were reached. Feeding was continued for another 70 hours (Step 2). The water content of 30 ppm by mass is less than the saturated water content under the above conditions. Then, under these conditions, butene mixed raw material (isobutylene 35% by mass, normal butenes 2% by mass, propylene 1% by mass, butanes 62% by mass) added with 300 mass ppm of this mixed raw material on a mass basis , LHSV7h- ^{1 was} supplied, and the dimerization reaction was carried out while extracting from the bottom (step 3). Under these reaction conditions, it was confirmed that the liquid phase state was maintained in the reactor, and the water content of 300 ppm by mass was less than the saturated water content. Table 1 shows the reaction results after 12 hours from the start of supplying the butene mixed raw material to the reactor. The phosphorus atom content in the reaction solution is also shown in Table 1. The olefin conversion rate and butene dimer yield were good, and the amount of phosphoric acid eluted into the reaction solution was at a low level without any problem.

In Table 2, “total butene conversion (%)”, “butene dimer selectivity (%)” and “butene dimer yield (%)” are values calculated from the following formulas, respectively.
Total butene conversion (%) = [1- (total butene mass concentration in product / total butene mass concentration in raw material)] × 100
Butene dimer selectivity (%) = (butene dimer mass concentration in product / (total butene mass concentration in raw material−total butene mass concentration in product)) × 100
Butene dimer yield (%) = total butene conversion × butene dimer selectivity / 100

  The phosphorous atom content (ppm) in the reaction solution is reduced to ascorbic acid and colored as molybdenum blue among the methods specified in JIS (Japanese Industrial Standards) K0102 “Factory Wastewater Test Method” as a total phosphorus analysis method Then, it was measured by a method of measuring with an absorptiometer.

When the solid nuclear magnetic resonance spectroscopy of phosphorus ( ³¹ P) was performed on the catalyst A after completion of the reaction, the composition of the supported phosphoric acid (mol% in terms of phosphorus atom, the same shall apply hereinafter) was 85% orthophosphoric acid, There was 15% pyrophosphoric acid and no polyphosphoric acid was present. Further, as a result of neutralization titration, the amount of phosphoric acid in the catalyst A was 34.4% by weight in terms of orthophosphoric acid. As a result of removing phosphoric acid by washing the catalyst A with water and drying, the ratio of the carrier to the total mass of the catalyst A Was 66.2% by mass.

(Example 2)
Each step was performed under the same conditions as in Example 1 except that 10% by mass of hexane containing isobutene was used as the medium used in Step 2 and the water content in the medium was set to 70 ppm by mass. The water content of 70 ppm by mass is less than the saturated water content under the conditions of step 2. The results are also shown in Table 1. As in Example 1, the olefin conversion rate and butene dimer yield were good, and the amount of phosphoric acid eluted into the reaction solution was at a low level with no problem.

(Comparative Example 1)
Each step was performed under the same conditions as in Example 1 except that Step 2 was not performed. The results are shown in Table 1. As can be seen from the table, by not performing Step 2, the elution of phosphoric acid into the reaction solution was at a very high level, and the olefin conversion rate and butene dimer yield in the reaction step (Step 3) were low.

(Comparative Example 2)
Each step was performed under the same conditions as in Example 1 except that hexane containing 20% by mass of isobutene was used as the medium used in Step 2. The results are shown in Table 1. As can be seen from the table, when the olefin content in the medium was increased to 20 mass, the amount of phosphoric acid eluted into the reaction solution was extremely large and the yield of butene dimer was also low. In addition, the ratio of orthophosphoric acid to the total phosphoric acid supported on the solid phosphoric acid after completion of the reaction is also lower than in the examples, and the condensation of orthophosphoric acid is proceeding under the dimerization reaction assumption. Became clear.

(Comparative Example 3)
Each step was performed under the same conditions as in Example 1 except that the reaction temperature of the olefin dimerization reaction step (step 3) was 50 ° C. Since the dimerization reaction temperature was as low as 50 ° C., the amount of phosphoric acid eluted into the reaction solution was large, and the yield of butene dimer was also low. In addition, the ratio of orthophosphoric acid to the total phosphoric acid supported on the solid phosphoric acid after completion of the reaction is also lower than in the examples, and the condensation of orthophosphoric acid is proceeding in the dimerization reaction process. Became clear.

Example 3
A solid phosphoric acid catalyst B was prepared in the same manner as in Example 1 using a silica granulated product having an average pore size of 50 nm and an average spherical particle size of 3.5 mm as a carrier. Using catalyst B, step 2 and step 3 were performed under the same conditions as in Example 1. The results are also shown in Table 1. Although the average particle diameter of the catalyst was slightly larger, the olefin conversion rate was slightly low, but it was a satisfactory level, and it was favorable with little elution of phosphoric acid into the reaction solution.

Example 4
A solid phosphoric acid catalyst C was prepared in the same manner as in Example 1 using a silica granulated product having an average pore size of 10 nm and an average spherical particle size of 2.3 mm as a carrier. Using catalyst C, step 2 and step 3 were performed under the same conditions as in Example 1. The results are also shown in Table 1. This seems to be due to the large average pore diameter, but the selectivity for butene dimer was somewhat low, but the yield was at a level that is not a problem. In addition, there was little elution of phosphoric acid into the reaction solution, which was a good result.

(Example 5)
A solid phosphoric acid catalyst D was prepared by carrying out step 1 in the same manner as in Example 1 using an approximately spherical silica granulated product having an average pore size of 100 nm and an average particle size of 2.3 mm as a carrier. Using catalyst D, steps 2 and 3 were performed under the same conditions as in Example 1. The results are also shown in Table 1. The olefin conversion rate, butene dimer yield, and elution level of phosphoric acid in the reaction solution were all good.

(Example 6)
While feeding hexane containing 30 mass ppm of water to the catalyst A prepared in the same manner as in Example 1 from the top of the reactor at 50 ml / h, the pressure reached 3.0 Mpa and the catalyst layer inlet temperature 90 ° C. after 2 hours. Reached. Feeding was continued for another 70 hours (Step 2). The water content of 30 ppm by mass is less than the saturated water content under the above conditions. Next, a butene mixed raw material (isobutylene 35% by mass, normal butenes 2% by mass, propylene 1% by mass, butanes 62% by mass) added with 5 mass ppm of the mixed raw material on a mass basis under these conditions. , LHSV7h- ^{1 was} supplied, and the dimerization reaction was carried out while extracting from the bottom (step 3). Under these reaction conditions, it was confirmed that the liquid phase state was maintained in the reactor. The solid phosphoric acid catalyst was taken out of the reactor 720 hours after the start of supplying the butene mixed raw material to the reactor. As a result of the reaction after 720 hours, the olefin conversion was 51%, the butene dimer selectivity was 68%, and the butene dimer yield was 35%. The phosphoric acid composition of this solid phosphoric acid catalyst was 2% orthophosphoric acid, 5% pyrophosphoric acid, and 93% polyphosphoric acid. As a result of neutralization titration, the amount of phosphoric acid in the catalyst was 20.4% in terms of orthophosphoric acid.
Using the above-mentioned deteriorated solid phosphoric acid catalyst instead of the silica granulated product, phosphoric acid was supported under the same conditions as in Example 1 to prepare a regenerated solid phosphoric acid catalyst. This is referred to as solid phosphoric acid catalyst E. Steps 2 and 3 were carried out using the solid phosphoric acid catalyst E under the same conditions as in Example 1 to carry out a dimerization reaction of butene. The results are shown in Table 1. The regenerated catalyst was inferior to the new catalyst A or D in terms of dimerization activity and dimer selectivity. Moreover, the elution of phosphoric acid into the reaction solution was extremely small, and there was no problem at all.

  According to the present invention, a high dimerization reaction activity and a high dimer yield can be realized using a solid phosphoric acid catalyst. In addition, according to the present invention, elution of phosphoric acid into the reaction solution can be suppressed to a very low level in the course of the dimerization reaction. Therefore, it is possible to reduce the equipment for removing the eluted phosphoric acid and to reduce the problem of equipment corrosion. Thereby, an olefin dimer can be produced economically.

Claims (9)

In a reactor containing a solid phosphoric acid catalyst in which phosphoric acid is supported on inorganic support particles, 0 to 15% by mass of olefin based on the total amount of the mixture, less than the saturated water content in the contact condition and 10 mass ppm or more A first mixture containing water and a predetermined medium is introduced, and in the state where the solid phosphoric acid catalyst and the first mixture are in contact with each other, the temperature inside the reactor is increased so as to satisfy predetermined contact conditions. A first step of boosting;
Into the reactor after the first step, a second mixture containing olefin and water of less than the saturated water content at the reaction temperature and 10 mass ppm or more is introduced, and in the presence of the solid phosphoric acid catalyst. A second step of performing a dimerization reaction of the olefin at a reaction temperature of 55 to 300 ° C. to obtain a reaction product containing the olefin dimer;
A process for producing an olefin dimer, comprising:   2. The production method according to claim 1, further comprising a third step of supporting and regenerating phosphoric acid on the solid phosphoric acid catalyst after the second step and supplying the solid phosphoric acid catalyst to the first step. .   The temperature at which phosphoric acid is supported on the solid phosphoric acid catalyst in the third step is 100 ° C. or less, and the phosphoric acid concentration used for supporting is 93% by mass or less as normal phosphoric acid. The manufacturing method according to claim 2.   The manufacturing method according to claim 1, wherein the medium is a liquid hydrocarbon.   The ratio of orthophosphoric acid in phosphoric acid of the solid phosphoric acid catalyst used in the first step is 60 mol% or more in terms of phosphorus atom, and the pore diameter is 15 to 200 nm, Item 5. The production method according to any one of Items 1 to 4.   The manufacturing method according to any one of claims 1 to 5, wherein a particle diameter of the inorganic carrier of the solid phosphoric acid catalyst used in the first step is 3.0 mm or less.   The production method according to any one of claims 1 to 6, wherein the dimerization reaction in the second step is performed in a liquid phase.   The manufacturing method as described in any one of Claims 1-7 whose said olefin is a C3-C7 monoolefin.   The olefin dimer obtained by the manufacturing method as described in any one of Claims 1-8.