JP2007268363A - Catalyst for dehydrating glycerol, method for preparing catalyst for dehydrating glycerol, method for preparing acrolein, and method for preparing acrolein derivative - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst for dehydrating glycerol having a long life capable of preparing acrolein, and a method for preparing the catalyst. <P>SOLUTION: The catalyst for dehydrating glycerol is comprised of phosphorous (P) and zirconium (Zr) and/or manganese (Mn) supported by a support. The method for preparing the catalyst for dehydrating glycerol comprises an impregnation step for impregnating a support with an aqueous solution containing P and Mn and/or Zr, a drying and solidifying step for drying and solidifying the impregnated support, and a calcination step for calcining the dried and solidified support. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glycerin dehydration catalyst, a method for producing the catalyst, and a method for producing acrolein and a method for producing an acrolein derivative using the catalyst.

  Biodiesel produced from vegetable oil is attracting attention not only as a substitute for fossil fuels but also because it emits less carbon dioxide, and demand is expected to increase. When this biodiesel is produced, glycerin is produced as a by-product, so it is necessary to make effective use of it. One embodiment of the use of glycerin includes the use of glycerin as a raw material for acrolein.

  For example, Patent Document 1 discloses that acrolein is produced by performing a gas phase dehydration reaction of glycerin using a catalyst prepared by immersing a support in an aqueous copper phosphate solution, followed by drying and firing. Yes. Patent Document 2 discloses that acrolein is produced by performing a gas-phase dehydration reaction of glycerin using a catalyst prepared by immersing a carrier in an aqueous phosphoric acid solution, drying and calcining. . However, the catalysts disclosed in Patent Documents 1 and 2 have a problem of short life.

Patent Document 3 discloses that acrolein is produced by dehydrating glycerin by a liquid phase reaction using a catalyst in which phosphoric acid is supported on an alumina carrier. However, acrolein can be obtained in a high yield when a catalyst having phosphoric acid supported on a carrier is used, but it is desired that the catalyst has a longer life. If a long-life catalyst can be used, acrolein derivatives such as acrylic acid, 1,3-propanediol, allyl alcohol, polyacrylic acid, polyacrylic acid salt, etc., which are conventionally known to be produced using acrolein as a raw material, can be used. It can be manufactured at low cost.
US Patent No. 1916743 French Patent Invention No. 695931 JP-A-6-217724

  In view of the above circumstances, an object of the present invention is to provide a catalyst for glycerin dehydration capable of producing acrolein and having a long life, and a method for producing the catalyst.

  As a result of repeated studies to realize a long-life catalyst, the present inventor has found that a long-life catalyst can be realized when Zr and / or Mn is supported together with P, and the present invention has been completed. That is, the present invention is a glycerol dehydration catalyst in which P and Zr and / or Mn are supported on a carrier.

  The present invention also includes an impregnation step of impregnating a carrier with an aqueous solution containing P and Mn and / or Zr, a drying step of drying the carrier, and a baking step of firing the dried carrier. It is a manufacturing method of the catalyst for glycerol dehydration which has.

In the impregnation step, the aqueous solution may contain one or more selected from Mn ₃ (PO ₄ ) ₂ , MnHPO ₄ , and Mn (H ₂ PO ₄ ) ₂ as P and Mn sources. The aqueous solution may be used as a P source, for example, PO ₄ ³⁻ , HPO ₄ ²⁻ , H ₂ PO ₄ ⁻ , P ₂ O ₇ ⁴⁻ , HP ₂ O ₇ ³⁻ , H ₂ P ₂ O ₇ ²⁻ , and H ₃ P ₂ O ₇ ^- may contain one or two or more selected from. Further, Mn and / or Zr may be contained in the aqueous solution as Mn ²⁺ and / or Zr ⁴⁺ .

  Moreover, this invention is a manufacturing method of acrolein which spin-dry | dehydrates glycerol in the coexistence of the said catalyst. In this method, it is preferable to dehydrate glycerin by a gas phase reaction in which vaporized glycerin is brought into contact with a catalyst.

  Moreover, this invention is a manufacturing method of the acrolein derivative which has the process of dehydrating glycerol in the presence of the said catalyst and manufacturing acrolein. Examples of the acrolein derivative include polyacrylic acid and polyacrylic acid salts such as sodium polyacrylate.

  According to the glycerin dehydration catalyst of the present invention, the Zr element and / or the Mn element are supported on the carrier together with the P element, so that the catalyst life becomes long.

  The present invention will be described based on an embodiment. The catalyst of the present embodiment includes a support, P supported on the support, and a specific metal element.

The carrier is not particularly limited in physical properties such as particle size and surface area. Moreover, although SiO ₂ , ZrO ₂ , TiO ₂ , Al ₂ O ₃ , MgO, zeolite, activated carbon and the like are not particularly limited, SiO ₂ is preferable.

  The carrier carries P element and a specific metal element, and the life of the catalyst is extended by carrying these elements. In addition, if a metal element other than Zr and Mn is selected, a long-life catalyst cannot be realized due to a large change over time in acrolein yield reduction, or before that, the acrolein yield is greatly inferior to that of a P-supported catalyst. Zr and / or Mn are selected as the metal element. Note that the P element is preferably supported as an oxide.

  As long as P and Mn and / or Zr are supported on the carrier, the supported amount is not particularly limited. Further, the ratio of P to Mn and / or Zr is not particularly limited.

  The catalyst of the present embodiment can be obtained by using the evaporation to dryness method, which is a class of impregnation method. In other words, a predetermined impregnating solution is impregnated with a powder or molded body carrier, water is evaporated to dry the carrier, P and Zr and / or Mn are fixed to the carrier, and then the carrier is fired. The catalyst of this embodiment can be obtained.

The impregnation liquid used in the process for producing the catalyst of the present embodiment is an aqueous solution containing P and Mn and / or Zr. That is, it does not matter whether P, Mn, and Zr are present as a single substance or a single composition in the impregnating liquid. For example, one or more selected from Mn ₃ (PO ₄ ) ₂ , MnHPO ₄ , and Mn (H ₂ PO ₄ ) ₂ , which are hardly soluble or insoluble in water, are contained in the impregnation liquid as P and Mn sources. Good to be. Further, P may be contained in the impregnation liquid as a phosphate ion serving as a P source to be supported on the carrier. Examples of the phosphate ion at this time include H ₃ PO ₄ , H ₄ P ₂ O, and the like. _7, and phosphoric acid and salts with ammonia _{(e.g., (NH 4) H 2 PO} 4) caused by the like are ion dissociation in water ^{_{PO 4 3-, HPO 4 2-,}} H 2 PO 4 -, P 2 One or two or more types selected from O ₇ ⁴⁻ , HP ₂ O ₇ ³⁻ , H ₂ P ₂ O ₇ ²⁻ , and H ₃ P ₂ O ₇ ⁻ can be mentioned. Further, Mn may be contained in the impregnating solution as Mn ²⁺ generated by ion dissociation of Mn (NO ₃ ) ₂ or the like, and Zr (NO ₃ ) ₄ or ZrO (NO ₃ ) ₂ is generated by ion dissociation. It is acceptable that Zr is contained in the impregnating solution as Zr ⁴⁺ .

  The temperature of the impregnating liquid when impregnating the carrier is not particularly limited, but may be 100 ° C. or lower, preferably 30 ° C. or higher, more preferably 50 ° C. or higher.

  The carrier may be fired at a firing temperature of 300 to 700 ° C., preferably 400 ° C. or higher, more preferably 500 ° C. or higher. Note that firing is preferably performed in an air atmosphere.

  Next, a method for producing acrolein using the catalyst of the present embodiment will be described. The method for producing acrolein in the present embodiment is to produce acrolein by a gas phase dehydration reaction in which a reaction gas containing glycerin is brought into contact with a catalyst in a reactor arbitrarily selected from a fixed bed reactor, a moving bed reactor and the like. It is. The catalyst according to the present invention is not limited to an acrolein manufacturing method in which a reaction gas and a catalyst are brought into contact with each other, and can also be used in a manufacturing method in which a glycerin solution and a catalyst are brought into contact with each other. In this case, a fluidized bed reactor or the like is selected as the reactor.

  The reaction gas may be a gas composed only of glycerin, and may contain an inert gas in the glycerin dehydration reaction in order to adjust the glycerin concentration in the reaction gas. Examples of the inert gas include vaporized water and nitrogen gas. The glycerin concentration in the reaction gas is preferably 0.1 to 100 mol%, preferably 1 mol% or more, and 10 mol% or more in order to produce acrolein economically and highly efficiently. .

Since the catalyst is a highly efficient glycerol dehydration catalyst, acrolein can be obtained in a high yield even when the flow rate of the reactive gas is set to be large. The flow rate of the reactive gas is preferably 100 to 10,000 hr ⁻¹ in terms of the reactive gas flow rate (GHSV) per unit catalyst volume. Preferred is a 5000 hr ^-1 or less, in order to perform the production of acrolein economically and efficiently is 3000 hr ^-1 or less.

  The reaction temperature may be 200 to 500 ° C, preferably 250 to 450 ° C, and more preferably 300 to 400 ° C.

  The pressure of the reaction gas is not particularly limited as long as the pressure is within a range where glycerin does not condense. Usually, it is good that it is normal-pressure-1MPa, Preferably, it is 0.5 MPa or less.

  Acrolein can be produced by the above method. As already known, the produced acrolein can be used as a raw material for producing acrolein derivatives such as acrylic acid, 1,3-propanediol, allyl alcohol, polyacrylic acid, and polyacrylate. Therefore, it is naturally possible to incorporate the acrolein production method described above into the acrolein derivative production method.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.

[Example 1]
A mixed solution was prepared by mixing and stirring 350 g of ion-exchanged water and 40 g of SiO ₂ powder, and the mixed solution was heated to 80 ° C. Next, 8.5523 g of Mn (H ₂ PO ₄ ) ₂ · 4H ₂ O dissolved in a small amount of ion-exchanged water is added to the mixed solution, and the impregnating solution (Mn (H ₂ PO ₄ ) ₂ -containing ion exchange is added. Water) was immersed in SiO ₂ , and then heated and stirred at 80 ° C. until it became a paste. Then, the paste-like material is dried at 100 ° C., the moisture is evaporated and P and Mn are fixed to the carrier, and then SiO ₂ is calcined in the atmosphere at 600 ° C. for 5 hours to obtain a catalyst. It was. After roughly pulverizing the obtained catalyst, a catalyst having a particle size of 0.7 to 2.0 mm was classified to obtain a glycerol dehydrating catalyst of Example 1. The Si, Mn, and P element compositions in the catalyst of Example 1 are Si ₅ Mn _0.4 P _0.4 .

[Example 2]
Instead of Mn (H ₂ PO ₄ ) ₂ · 4H ₂ O used in Example 1, 7.1573 g of ZrO (NO ₃ ) ₂ · 2H ₂ O and 6.1507 g of 85 mass% H ₃ PO ₄ aqueous solution were used. A catalyst of Example 2 was prepared in the same manner as Example 1 except that. The Si, Zr, and P element compositions in the catalyst of Example 2 are Si ₅ Zr _0.2 P _0.4 .

[Comparative Examples 1-6]
Catalysts of Comparative Examples 1 to 6 were prepared in the same manner as in Example 1 except that Mn (H ₂ PO ₄ ) ₂ · 4H ₂ O used in Example 1 was changed. That is, instead of Mn (H ₂ PO ₄ ) ₂ .4H ₂ O of Example 1, 3.0640 g of (NH ₄ ) H ₂ PO ₄ is used in Comparative Example 1, and Cu ₃ (PO ₃ is used in Comparative Example 2. ) ₂ was used at 10.1467 g, Comparative Example 3 was used at 5.9355 g FePO ₄ .4H ₂ O, Comparative Example ₄ was used at 3.2469 g AlPO ₄ , and Comparative Example 5 was used at Fe ₄ (P ₂ O ₇ ) ₃ use 19.8773G, in Comparative example 6 Zn _{3 (PO 4) 2 · 4H 2} O was used 12.8515G. In the prepared catalyst, the elemental composition excluding oxygen element is as follows: Si ₅ P _0.2 (Comparative Example 1), Si ₅ Cu _0.6 P _0.2 (Comparative Example 2), Si ₅ Fe _0.2 P _0.2 (Comparative Example 3), Si ₅ Al _0.2 P _0.2 (Comparative Example 4), Si ₅ Fe _0.8 P _1.2 (Comparative Example 5), and Si ₅ Zn _0.6 P _0.4 (Comparative Example 6).

[Comparative Example 7]
After firing Mn (H ₂ PO ₄ ) ₂ .4H ₂ O in the atmosphere at 600 ° C. for 5 hours, the obtained powder was pressure-formed into a disk shape. Next, after roughly pulverizing the molded product, a classified product having a particle size of 0.7 to 2.0 mm was used as a glycerol dehydration catalyst of Comparative Example 7.

[Manufacture of acrolein]
Acrolein was synthesized by dehydrating glycerol by the following method using a reactor in which the catalysts of Examples and Comparative Examples were fixed beds.

First, a stainless steel reaction tube (inner diameter: 10 mm, length: 500 mm) filled with 15 ml of the catalyst of Example or Comparative Example was prepared as a fixed bed reactor, and this reactor was immersed in a salt bath at 360 ° C. Thereafter, nitrogen was circulated in the reactor at a flow rate of 61.5 ml / min for 30 minutes, and then a reaction gas composed of a vaporized gas of 80 mass% glycerin aqueous solution and nitrogen (reaction gas composition: glycerin 27 mol%, water 34 mol%, nitrogen 39 mol%) was circulated at a flow rate of 632hr ^-1.

  The effluent gas for 30 to 60 minutes and 150 to 180 minutes after flowing the reaction gas through the reactor was cooled and liquefied and collected (hereinafter referred to as “cooled liquefied product of the collected effluent gas”). Referred to as “spill”). In addition, the effluent in 330-360 minutes was obtained only for the reaction using the catalyst of Example 1. Then, qualitative and quantitative analysis of the effluent was performed by gas chromatography (GC). As a result of qualitative analysis by GC, 1-hydroxyacetone was detected together with glycerin and acrolein. Further, the conversion rate and yield were calculated from the quantitative analysis results. Here, the conversion rate is a value calculated by (1− (number of moles of glycerin in the collected effluent) / (number of moles of glycerin introduced into the reactor in 30 minutes)) × 100. The yield of acrolein is a value calculated by ((molar number of acrolein) / (molar number of glycerin introduced into the reactor in 30 minutes)) × 100.

  Table 1 below shows the results of GC analysis.

  As shown in Table 1 above, it can be confirmed that the yield of acrolein is high and the decrease in acrolein yield is small only when the catalyst of the example in which Zr and Mn are supported is used.

Claims (9)

  A catalyst for dehydration of glycerol, wherein P and Zr and / or Mn are supported on a carrier.   Characterized by comprising an impregnation step of impregnating a carrier with an aqueous solution containing P and Mn and / or Zr, a drying step of drying the carrier, and a firing step of firing the dried carrier. A method for producing a catalyst for dehydration of glycerin. In the impregnation step, according to claim 2 wherein the aqueous solution containing _{Mn 3 (PO 4) 2,} MnHPO 4, and Mn (H ₂ PO ₄₎ one or more selected from ₂ as P and Mn source Of producing a glycerol dehydration catalyst.   The method for producing a glycerol dehydration catalyst according to claim 2 or 3, wherein, in the impregnation step, the aqueous solution contains a phosphate ion as a P source. The phosphate ions are PO ₄ ³⁻ , HPO ₄ ²⁻ , H ₂ PO ₄ ⁻ , P ₂ O ₇ ⁴⁻ , HP ₂ O ₇ ³⁻ , H ₂ P ₂ O ₇ ²⁻ , and H ₃ P _2. O ₇ ^- one or manufacturing method of the glycerin dehydration catalyst according to the is claim 4 two or more selected from. The method for producing a glycerol dehydration catalyst according to any one of claims 2 to 5, wherein Mn and / or Zr is contained in the aqueous solution as Mn2 ⁺ and / or Zr4 ^{+ in} the aqueous solution in the impregnation step.   A method for producing acrolein by dehydrating glycerol in the presence of a catalyst, wherein the catalyst is the glycerol dehydrating catalyst according to claim 1.   The method for producing acrolein according to claim 7, wherein glycerin is dehydrated by a gas phase reaction in which vaporized glycerin is brought into contact with a catalyst.   A method for producing an acrolein derivative comprising a step of producing acrolein by dehydrating glycerol in the presence of a catalyst, wherein the catalyst is the glycerol dehydration catalyst according to claim 1. Method.