JP2009149576A - Process for preparing glycidol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for preparing glycidol from glycerin carbonate with a high selectivity without having an agitation device or the like in the reactor and without requiring a catalyst separation operation in the post-step. <P>SOLUTION: The process for preparing glycidol comprises decarboxylating glycerin carbonate with the use of a tubular reactor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing glycidol from glycerin carbonate using a tubular reactor.

Glycidol is a substance useful as a raw material for polyglycerin, (poly) glycerin ester, dihydroxypropylamine and the like, cosmetics, detergents, pharmaceuticals, paints, semiconductor UV curing agents and the like.
As a method for producing glycidols, Patent Documents 1 and 2 disclose a method of decarboxylating glycerin carbonate in the presence of a neutral salt such as sodium sulfate.
Patent Document 3 discloses a method of decarboxylating glycerin carbonate using a solid catalyst such as A zeolite or γ-alumina, and describes a continuous batch type apparatus and a thin film type apparatus.
However, the conventional method is disadvantageous in industrial production because it is necessary to equip the reactor with a stirrer or the like, or a separation operation such as catalyst filtration is required in a subsequent process.

JP-A-6-157509 U.S. Pat. No. 2,856,413 US Pat. No. 6,316,641

  An object of the present invention is to provide a method for producing glycidol from glycerin carbonate with high selectivity without providing a reactor with a stirrer or the like and without the need for a catalyst separation operation in a subsequent step.

  The present invention provides a method for producing glycidol by decarboxylating glycerin carbonate using a tubular reactor.

  According to the present invention, glycidol can be produced with high selectivity using glycerol carbonate as a raw material and a simple reactor called a tubular reactor. In addition, a separation device such as a stirring device or catalyst filtration in a subsequent process is unnecessary, which is advantageous in industrial production.

The method for producing glycidol according to the present invention is characterized in that glycidol is obtained by decarboxylating glycerol carbonate using a tubular reactor.
(Manufacture of glycidol)
As shown in the following reaction formula, the glycidol represented by the formula (2) is obtained by supplying the glycerin carbonate represented by the following formula (1) to the tubular reactor and decarboxylating the glycidol. can get.

  Since water in the reaction system may cause hydrolysis of glycerin carbonate and glycidol, which are raw materials, it is preferable to use glycerin carbonate that has been dehydrated and purified in advance. Although the dehydration method is not particularly limited, for example, it can be dehydrated and dried by a conventional method such as using a desiccant such as a metal hydride.

In the present invention, glycerin carbonate as a raw material is supplied to a tubular reactor, a decarboxylation reaction is carried out in the tubular reactor, and the produced glycidol is cooled and obtained.
(Tube type reactor)
There is no restriction | limiting in particular in the tubular reactor used by this invention. For example, a single-tube type reactor (one reaction tube) or a parallel multi-tube type (multiple reaction tubes) consisting of a straight tube or a bent tube of a predetermined length can be used. Is more preferable. In the present invention, it is possible to use a tubular catalyst-free reactor that does not charge the catalyst in the reactor, so that glycidol is highly selectively produced by decarboxylating glycerol carbonate while being simple. Can do. Moreover, a catalyst separation step such as a catalyst stirrer or catalyst filtration in a subsequent step is unnecessary, which is advantageous in industrial production.
The tubular reactor is provided with heating means for maintaining the inside at a desired temperature and pressure. There is no restriction on the heating type, and a double-pipe heating type or an electric heater type using a heat medium or high-pressure steam can be adopted.

The material of the tubular reactor is not particularly limited, but stainless steel, nickel-containing metals (nickel, monel metal, inconel (registered trademark), hastelloy (registered) from the viewpoint of wear resistance, corrosion resistance, workability, economy, etc. Etc.), metals such as palladium alloys, titanium alloys, chromium / tungsten alloys (Stellite (registered trademark)), ceramics, and glass are preferred.
Among these, stainless steel is particularly preferable from the viewpoints of workability, corrosion resistance, economy, and the like. Examples of stainless steel include SUS-316L (austenite), SUS-310S (austenite), SUS-440 (martensite), and SUS-630 (precipitation hardening).
Moreover, when a tubular reactor having a catalytic action such as a nickel-containing metal is used, the conversion rate, selectivity, and yield can be further improved.

(Decarboxylation reaction conditions)
The reaction temperature is preferably 200 to 350 ° C, more preferably 240 to 340 ° C, still more preferably 260 to 330 ° C, and particularly preferably 280 to 320 ° C. If the temperature is 200 ° C. or higher, the reaction can be carried out rapidly even without a catalyst. Moreover, if it is the temperature of 350 degrees C or less, since the raw material glycerol carbonate will not be completely gasified, the residence time required for reaction can be ensured, and the yield of glycidol will not fall.
The reaction pressure is not particularly limited, but is preferably 10 to 200 kPa, more preferably 50 to 150 kPa.

When the reaction is carried out continuously in a tubular reactor, the glycidol produced by decarboxylation from glycerin carbonate is quickly transferred out of the tubular reactor and taken out into the gas system. From the viewpoint of lowering, it is preferable to supply an inert gas together with carbonate. The selectivity of glycidol can be improved by supplying an inert gas.
The type of the inert gas is not particularly limited, but nitrogen gas is preferable from the viewpoint of economy and the like. The supply amount of the inert gas varies depending on the reaction temperature, the reaction pressure, and the like, but may be an amount that allows the glycidol to be produced to stay in a substantially constant state without staying in the reaction system. Specifically, from the above viewpoint, the carbonate flow rate is preferably 0.1 to 10 mol times, more preferably 0.5 to 8 mol times, further preferably 1 to 6 mol times, and more preferably 2 to 4 mols. Double is particularly preferred.

The liquid space velocity (LHSV) when the decarboxylation reaction is continuously carried out in a tubular reactor is preferably 0.02 to 3.0 / hr, more preferably 0.2 to 2.0 / hr, More preferably, it is 0.5-1.8 / hr. High productivity per unit volume of the reactor is maintained under conditions where LHSV is 0.02 / hr or more, and a sufficient reaction rate can be obtained under conditions where LHSV is 3.0 / hr or less.
In the present invention, glycerin carbonate as a raw material is supplied to a tubular reactor and continuously decarboxylated, and the produced glycidol and unreacted glycerin carbonate can be cooled and collected separately by a conventional method. . The recovered unreacted glycerin carbonate can be supplied again to the tubular reactor as a raw material of the present invention.

Practical example 1
A SUS tube (SUS-316) having an inner diameter of 4.4 mmφ and a length of 200 mm was used as a tubular reactor. The raw material glycerol carbonate was supplied at 4.6 g / hr (LHSV: 1.54 / hr), and 3 moles of nitrogen was simultaneously supplied at 44 cc / min with respect to glycerol carbonate. A decarboxylation reaction was performed at a tube reactor temperature of 300 ° C. and a pressure of 101 kPa, and the reaction mixture (3.9 g / hr) was collected, separated into glycidol and unreacted glycerin carbonate, and collected.
As a result of analyzing the resulting reaction mixture, the yield of glycidol was 8.4% by mass, and 91.6% by mass was unreacted glycerin carbonate and by-products. The conversion was 21% by mass and the selectivity was 40% by mass.

Comparative Example 1
In a 500 ml round bottom flask equipped with a thermometer and mechanical stirrer, put 250.2 g of glycerin carbonate, and heat the contents of the flask to a temperature of 220 ° C. in an oil bath. Then, the pressure was reduced to 8 kPa, and a batch reaction was performed. The product distilled from the flask was condensed as it was through the cooling tube and collected in the collecting tube.
As a result of analyzing the obtained product, the yield of glycidol in the collecting tube was 0.24% by mass, and the others were unreacted glycerin carbonate and by-products. The conversion was 7.9% by mass, and the selectivity was 3.0% by mass.

Practical example 2
In Example 1, a nickel tube (nickel purity 99.5% by mass) having an inner diameter of 4.4 mmφ and a length of 200 mm was used as a tubular reactor, and glycerol carbonate was 4.6 g / hr (LHSV: 1.54 / hr). ), And 3 moles of nitrogen with respect to glycerin carbonate was simultaneously supplied at 44 cc / min. A decarboxylation reaction was performed at a tube reactor temperature of 300 ° C. and a pressure of 101 kPa, and the reaction mixture (3.9 g / hr) was collected, separated into glycidol and unreacted glycerin carbonate and collected.
As a result of analyzing the resulting reaction mixture, the yield of glycidol was 35% by mass, and the others were unreacted glycerin carbonate and by-products. The conversion was 41% by mass and the selectivity was 87% by mass.

Claims (5)

  A method for producing glycidol by decarboxylating glycerin carbonate using a tubular reactor.   The method for producing glycidol according to claim 1, wherein the decarboxylation reaction is performed at 200 to 350 ° C.   The manufacturing method of glycidol of Claim 1 or 2 performed by introduce | transducing 0.1-10 mol times inert gas with respect to glycerol carbonate.   The manufacturing method of glycidol in any one of Claims 1-3 whose liquid space velocity (LHSV) in a tubular reactor is 0.02-3.0 / hr.   The manufacturing method of the glycidol in any one of Claims 1-4 whose material of a tubular reactor is stainless steel or a nickel containing metal.