JP2008137949A - Manufacturing method of acrolein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an economically advantageous method for manufacturing acrolein in a high yield using glycerin of high concentration as a raw material. <P>SOLUTION: Acrolein is manufactured by subjecting glycerin to a dehydration reaction under a reduced pressure condition. That is, the manufacturing method of acrolein comprises forming acrolein from glycerin using a solid catalyst in a gas phase reaction, where the reaction is carried out under a condition of a pressure at an inlet of the reactor of at least 1 kPa and at most 90 kPa. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reaction for dehydration of glycerin, and particularly to acrolein production by dehydration of glycerin.

  One embodiment of the use of glycerin includes the use of glycerin as a raw material for acrolein. Acrolein is a useful compound used as a raw material for acrolein derivatives such as 1,3-propanediol, methionine, acrylic acid, and 3-methylpropionaldehyde.

  So far, a process for producing acrolein using glycerin as a raw material has already been known. For example, a glycerin concentration of 50% by mass or less under a normal pressure gas phase condition (a glycerin concentration of 16 mol% or less in a reactor inlet gas composition). A glycerin aqueous solution is used as a raw material, and a larger amount of water than glycerin is supplied to the reactor to carry out the reaction (see Patent Document 1).

  Also disclosed is a method for producing acrylic acid by producing acrolein by vapor phase dehydration as a glycerin raw material, and subsequently carrying out a second stage oxidation reaction. The reaction for producing acrolein by vapor-phase dehydration as the first-stage glycerin raw material is supplied to the reactor although the amount of water added to the glycerin raw material under normal-pressure gas-phase conditions is regulated to 50 mass% or less. As the reactor inlet gas, an inert gas such as nitrogen is added, and the reaction is carried out under the condition that the inert gas concentration becomes 50 mol% or more (glycerin concentration of 10 to 14 mol% in the reactor inlet gas composition) ( Patent Document 2).

  A reaction using only glycerin using helium gas as a diluent gas without adding water is also disclosed. Although there is no description of a clear yield, the yield is inadequate (refer nonpatent literature 1).

  In general, by increasing the concentration of the reaction raw material, it is possible to reduce fixed costs by reducing productivity and reducing the reactor size, reducing variable costs required for material evaporation, heating, product separation and purification, etc. Many advantages are expected compared to the case of using low concentration raw materials.

  When using low-concentration glycerin gas as the raw material of the reactor inlet gas composition shown in the patent literature and non-patent literature, there is concern about the decrease in productivity and the increase in equipment cost due to the increase in reactor size. Is done.

  Furthermore, in order to perform a gas phase reaction as a low concentration glycerin aqueous solution raw material shown in Patent Documents 1 and 2, not only a large amount of energy is required to evaporate a large amount of water, but also the obtained gas When condensing and collecting in order to obtain acrolein from the gaseous product, a large amount of water vapor is condensed, and there is a problem that a large amount of energy is required in the collecting process.

  In addition, as shown in Non-Patent Document 1, when a non-condensable gas such as helium gas is added to the raw material gas, there is a concern about loss due to scattering of acrolein when condensing and collecting the product acrolein. . In addition to these, further improvements are desired in terms of acrolein yield and catalyst life.

  However, these documents do not mention the effect of carrying out the reaction under reduced pressure conditions. In addition, when producing acrolein from glycerin, what kind of reaction conditions should be selected to produce the product acrolein in a higher yield, improve the collection efficiency of the produced acrolein, There is no description or suggestion as to whether the glycerin concentration can be increased without reducing the reaction yield in order to improve productivity from the standpoint.

International Publication WO2006-070884 JP 2005-213225 A Le H. Dao, Reaction of Models Compounds of Biomass-Pyrolysis Oils Over ZSM-5 Zeolites Catalysts, American Chemical Society, 1988, 376, p. 32 8-341

  In view of the above circumstances, the present invention provides a method for improving acrolein yield and catalyst life as well as a method for producing acrolein with high efficiency by using a high-concentration glycerin raw material when dehydrating glycerin to produce acrolein. The purpose is to provide.

  As a result of intensive investigations on glycerin high-concentration reaction conditions that improve productivity when assuming industrial implementation, the present invention improves productivity in the production of acrolein from high-concentration glycerin if reduced pressure reaction conditions are selected. I found.

  That is, when acrolein is produced by vapor phase dehydration reaction using high-concentration glycerin as a raw material under normal pressure conditions, the acrolein yield is reduced as compared with low-concentration conditions. In contrast, for non-condensable gas and condensable gas, which are dilute (entrained) gas accompanied by the glycerin gas of the raw material under specific decompression conditions, high concentration glycerin is used as the raw material without using them. It has been found that even if acrolein is produced, a decrease in acrolein yield can be prevented, and the present invention has been completed.

  In normal dehydration reactions, water coexisting in the reaction system is a concern, such as adversely affecting the reaction. However, in the reaction of dehydrating glycerin to produce acrolein, water is also present as shown in the patent document. This is desirable from the standpoint of acrolein yield and catalyst life, which is a phenomenon peculiar to this reaction.

  However, according to the method of the present invention, by carrying out the gas phase dehydration reaction of glycerin to acrolein under reduced pressure conditions, a high concentration glycerin raw material can be used without reducing the yield even under conditions where water does not coexist. Acrolein can be produced in a yield.

  For this reason, acrolein can be produced economically with high efficiency without the enormous energy loss accompanying evaporation and liquefaction of a large amount of water as shown in the patent literature. Further, as the productivity is improved, the reactor size can be made compact, so that the equipment cost can be reduced.

  When an inert gas such as nitrogen is reacted as a carrier gas under normal pressure conditions, it is difficult to control the concentration. Generally, glycerin gas is generated by a glycerin evaporator, and the generated gas passes through a flow rate control valve. Supply glycerin gas. Thereafter, it is mixed with a carrier gas to obtain a reactor inlet gas. At that time, since the pressure loss of the flow control valve cannot be ignored, the pressure in the evaporator becomes a pressurizing condition, and the boiling point of glycerin rises accordingly. Is expected to be required.

  On the other hand, under the reduced pressure reaction conditions, the temperature of the glycerin evaporator can be lowered according to the degree of decompression, and the effect of reducing the loss of glycerin due to decomposition or polymerization of glycerin in the evaporator part is expected. Can do.

  In addition, there is no need to supply additional water, which is a condensed gas component, or nitrogen, which is a non-condensed gas component, and the pressure loss in the catalyst layer is also reduced, and the effect of avoiding the negative impact on the acrolein yield due to pressure loss is also expected be able to.

  Furthermore, acrolein can be more easily condensed and collected under reduced pressure conditions in which a non-condensable gas such as nitrogen does not need to coexist as a carrier gas, and acrolein can be produced with higher efficiency.

  A method for producing acrolein by dehydration reaction of glycerin according to the present invention will be described based on an embodiment.

(Reaction format)
The reaction for producing acrolein by dehydration reaction of glycerin performed under reduced pressure conditions can be preferably performed under gas phase reaction conditions. The form of the gas phase reaction can be arbitrarily selected, such as a fixed bed flow form and a fluid bed flow form, but the fixed bed flow form is the simplest and preferable.

  The reactor inlet gas that is circulated through the fixed bed reactor may contain a dilute (entrained) gas in order to adjust the glycerin concentration. It is not necessary to add a dilution gas unless particularly necessary.

  As the diluent gas, any condensable gas or non-condensable gas can be used as long as it does not adversely affect the dehydration reaction from glycerin to acrolein, but condensable gas can be used from the viewpoint of more easily condensing and collecting acrolein. Is desirable.

  A condensable gas that can be used as a dilution gas is a gas of a compound having a boiling point higher than that of acrolein and a boiling point of 200 ° C. or less under normal pressure conditions. For example, an alkane compound such as water vapor, hexane, heptane, octane, cyclohexane Examples of the gas include aromatic gases such as gas, benzene, toluene, xylene, mesitylene, and ethylbenzene.

  The non-condensable gas is a compound having a boiling point of 0 ° C. or lower under normal pressure conditions or a single gas, for example, nitrogen-containing gas, carbon dioxide gas, oxygen-containing gas such as air, or rare gas such as helium. be able to. These condensable gases and non-condensable gases may be used alone or as a mixture of two or more.

  The reaction pressure can be set arbitrarily, but it may be 1 kPa or more and 90 kPa or less, preferably 3 kPa or more and 80 kPa or less, more preferably 5 kPa or more and 70 kPa or less. Under pressure conditions below this range, it is not possible to obtain an effect that is commensurate with the cost of equipment such as a highly airtight reactor and the operating cost of production equipment. In addition, it is difficult to collect acrolein, and there is a concern about a decrease in yield.

  The glycerin concentration in the reactor inlet gas can be arbitrarily set using the dilution gas described above, but is 20 mol% or more, preferably 40 mol% or more, more preferably 90 mol% or more. If the glycerin concentration is within this range, it is preferable because productivity of acrolein can be improved and energy required for acrolein production can be reduced.

  The amount of diluent (gas) used as necessary may be 10 mol% or less, preferably 8 mol% or less, more preferably 5 mol% or less for non-condensable gases such as nitrogen. . Further, the concentration of the condensable gas such as water is 80 mol% or less, preferably 40 mol% or less, more preferably 10 mol% or less. If the non-condensable gas concentration is within this range, it is preferable because energy when heating or cooling the gas can be reduced and scattering loss when collecting acrolein can be reduced. In addition, if the condensable gas is within this range, energy can be reduced as in the case of the non-condensable gas, and the separation cost of the diluent can be reduced.

  The temperature of the glycerin evaporator necessary for vaporizing glycerin is preferably lowered in order to reduce the loss of glycerin due to decomposition of glycerin in the evaporator part. Under reduced pressure reaction conditions, the temperature of the glycerin evaporator can be reduced by the degree of reduced pressure, and it may be 120 ° C. to 285 ° C., preferably 160 ° C. to 270 ° C., more preferably 190 ° C. to 260 ° C. is there.

The flow rate of the reactor inlet gas, the reaction gas flow rate (space velocity, SV) of the atmospheric pressure in terms of per unit catalyst volume may If it is 10～10000Hr ^-1 Expressed in, preferably 30～5000Hr ^-1, further Preferably, it is 50 to 3000 hr ⁻¹ .

  The temperature at which the reaction gas is circulated and the dehydration reaction of glycerin is performed is preferably 200 to 500 ° C, preferably 250 to 450 ° C, more preferably 300 to 400 ° C.

(Solid catalyst)
The solid catalyst used in the present invention can be arbitrarily used as long as it can produce acrolein by vapor-phase dehydration of glycerin under normal pressure conditions. Examples of the catalyst include so-called solid acids. As the solid acid catalyst, any compound having solid acidity may be used. (1) Crystalline metallosilicate, (2) Metal oxide, (3) Clay mineral, (4) Carrying mineral acid, (5) Examples thereof include metal salts of phosphoric acid and sulfuric acid and those carrying them.

  (1) As a crystalline metallosilicate, one or more elements selected from Al, B, Fe, Ga and the like are T atoms, and the crystal structure thereof is LTA, CHA, FER, MFI, MOR, BEA, MTW, etc. (2) As the metal oxide, in addition to a single metal oxide such as Al2O3, TiO2, ZrO2, SnO2, V2O5, etc., SiO2-Al2O3, SiO2-TiO2, TiO2-WO3, WO3-ZrO2 (3) As clay minerals, bentonite, kaolin, montmorillonite, etc. (4) As those carrying mineral acids, phosphoric acid or sulfuric acid carried on alumina, silica, zirconia, etc. (5) Metal salts of phosphoric acid and sulfuric acid include MgSO4, Al2 (SO4) 3, K2SO4, AlPO4, Zr3 ( O4) 4 and the like.

  Specifically, a solid acid (such as zirconium oxide carrying phosphoric acid, sulfuric acid, or tungsten oxide) disclosed in Patent Document 1 or International Publication WO2006 / 087083 can also be used.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the scope of the present invention is not limited only to these Examples. The glycerin conversion rate, acrolein yield, and SV (space velocity) are values calculated by the following formula.

Glycerin conversion rate = (1− (number of moles of glycerin in the collected effluent) / (number of moles of glycerin introduced into the reactor in 30 minutes)) × 100
Yield of acrolein = ((number of moles of acrolein in the collected effluent) / (number of moles of glycerin introduced into the reactor in 30 minutes)) × 100
SV (space velocity) = (gas supply amount converted under standard conditions, L / hr) / (catalyst amount, L).

(Catalyst Preparation Example 1)
By executing the following supporting process, crystallization process, and ion exchange process, H-type MFI catalysts (methanosilicate molded bodies in which T atoms are Al) of each Example and Comparative Example were produced.

(Supporting process)
1.40 g of NaOH and 0.47 g of NaAlO 2 were sequentially dissolved in 15.00 g of distilled water, and 10.15 g of 40 mass% tetra-n-propinoleammonium hydroxide aqueous solution was added to the distilled water. Then, distilled water was added to this solution to prepare an impregnating solution having a total amount of 30 ml.

  Next, silica beads (“CARTIACT Q50” manufactured by Fuji Silysia Chemical Co., Ltd., 10 to 20 mesh, average pore diameter 50 nm) are used as the silica molded body, and 30 g of silica beads dried at 120 ° C. for 1 day is used as the impregnation liquid. Impregnation for 1 hour. Thereafter, the silica beads were dried on an evaporating dish placed on a 100 ° C. hot water bath, and further dried at 80 ° C. under a nitrogen stream for 7 hours to obtain Na and Al crystallizing agents necessary for crystallization. A crystalline methanosilicate precursor was obtained by supporting it on beads.

(Crystallization process)
The precursor obtained in the supporting step is placed in the hollow part of a tetrafluoroethylene jacketed crucible having a volume of 100 ml, and 1.00 g of distilled water is placed at the bottom of the crucible, and this crucible is placed in an electric furnace at 180 ° C. for 8 hours. Left to stand.

(Ion exchange process)
The solid after the crystallization process was immersed in 300 g of a 1 mol / L ammonium nitrate aqueous solution at 60 ° C. and stirred for 1 hour, and then the supernatant was discarded. This operation was repeated several times. Thereafter, the solid was washed with water.

(Baking process)
The solid after the ion exchange step was baked at 540 ° C. for 3.5 hours in an air stream. By this calcination, an H-type MFI catalyst used in the following Examples and Comparative Examples was obtained.

(Example 1)
Using a fixed bed reactor capable of reducing the pressure, glycerol was dehydrated by the following method to produce acrolein.

  An evaporator filled with glass balls having an outer diameter of 3 mm was provided on the inlet side of the reactor, and the temperature of the evaporator was controlled while monitoring the temperature with a thermocouple inserted in the evaporator. The reaction pressure was controlled using a vacuum pump and a constant pressure reduction device while monitoring with a pressure gauge provided at the reactor inlet.

  A cooler was provided at the outlet of the reactor. 15 ml of the catalyst shown in Catalyst Preparation Example 1 was filled in a stainless steel reaction tube (inner diameter 10 mm, length 500 mm), and this reactor was immersed in a 360 ° C. molten salt bath. After reducing the pressure in the reactor to 62 kPa and allowing it to stand for 30 minutes, an 80 mass% glycerin aqueous solution was supplied to the evaporator with a liquid feed pump. In addition, the temperature of the evaporator at the time of evaporating 80 mass% glycerol aqueous solution on these reaction conditions was 192 degreeC.

Reactor inlet gas (reactor inlet gas composition: glycerin 44 mol%, water 56 mol%) composed of a vaporized gas of an 80 mass% glycerin aqueous solution was circulated through the reactor at a flow rate of SV value 490 hr ⁻¹ . After flowing the reactor inlet gas through the reactor, the entire amount of the effluent gas in 30 minutes between 0.5 to 1 hour and 2.5 to 3 hours is collected in a receiver cooled with dry ice-methanol. It was collected.

  The inside of the receiver was returned to normal pressure, a part of the effluent was taken, and qualitative and quantitative analysis of the effluent was performed by gas chromatography (GC). As a result of qualitative analysis by GC, by-products such as 1-hydroxyacetone were detected together with glycerin and acrolein. Further, the conversion rate, acrolein yield, and acrolein yield were calculated from the quantitative analysis results.

  The obtained reaction results are shown in Table 1.

(Example 2)
The reaction was carried out in the same manner as in Example 1 except that the pressure in the reactor was reduced to 27 kPa, and the reactor inlet gas consisting of 100 mol% of glycerin was circulated at a flow rate of SV value 180 hr ⁻¹ . The obtained reaction results are shown in Table 1.

  In addition, the temperature of the evaporator at the time of evaporating a glycerol liquid on these reaction conditions was 244 degreeC.

(Comparative Example 1)
The reaction was carried out under conditions comparable to those of Examples 1 and 2 using nitrogen gas, which is a non-condensable gas, under normal pressure conditions. Using a fixed bed reactor using nitrogen gas as a carrier gas, glycerin was dehydrated by the following method to produce acrolein.

  15 ml of the catalyst shown in Catalyst Preparation Example 1 was filled in a stainless steel reaction tube (inner diameter 10 mm, length 500 mm), and this reactor was immersed in a 360 ° C. molten salt bath. After circulating nitrogen through the reactor at a flow rate of 62 ml / min for 30 minutes, the glycerin solution was supplied to the evaporator with a feed pump.

  In addition, the temperature of the evaporator at the time of evaporating a glycerol liquid on these reaction conditions was 290 degreeC or more.

Reactor inlet gas (reactor inlet gas composition: glycerin 27 mol%, nitrogen 73 mol%) composed of the vaporized gas of glycerol and nitrogen was circulated at a flow rate of 650 hr ⁻¹ . By reducing the partial pressure of nitrogen under these reaction conditions, the conditions shown in Example 2 are obtained. After flowing the reactor inlet gas through the reactor, the effluent gas for 30 minutes is absorbed in water for 0.5 to 1 hour and 2.5 to 3 hours, and a part of the absorbed liquid is taken and implemented. Qualitative and quantitative analysis of the effluent was performed by the method shown in Example 1.

  The obtained reaction results are shown in Table 1. In the gas phase reaction reaction, it is generally known that almost the same performance can be obtained by combining the raw material partial pressures, but in this reaction, a unique effect was found under reduced pressure reaction conditions.

As shown in Table 1, it can be seen that in the reaction of acrolein synthesis from glycerin, a high acrolein yield can be obtained even under reaction conditions in which water is not coexisting using high-concentration glycerin gas as a raw material by performing the reaction under reduced pressure conditions.

  When acrolein is produced by dehydration reaction of glycerin under the reduced pressure condition of the present invention, the addition of water becomes unnecessary and a high yield of acrolein can be obtained economically and efficiently.

Claims (4)

A method for producing acrolein, characterized in that, in a gas phase reaction in which acrolein is produced from glycerin using a solid catalyst, the reaction is carried out under a condition where the pressure at the reactor inlet is 1 kPa or more and 90 kPa or less. The method for producing acrolein according to claim 1, wherein the concentration of the non-condensable gas in the reactor inlet gas is 10 mol% or less. The method for producing acrolein according to claim 1 or 2, wherein the concentration of the condensable gas other than glycerin in the reactor inlet gas is 60 mol% or less. The method for producing acrolein according to claim 1, wherein the temperature of the glycerin evaporator is 285 ° C. or lower.