JPWO2009110402A1 - Method for producing para-xylene - Google Patents

Abstract

A process for producing para-xylene using 2,5-dimethylfuran and ethylene as raw materials and comprising a Diels-Alder reaction and a dehydration reaction as steps. The present invention provides a method for producing paraxylene using dimethylfuran and ethylene synthesized from glucose, which is a non-petroleum material, as raw materials.

Description

  The present invention relates to a method for producing para-xylene.

  In recent years, destabilization of crude oil prices, carbon dioxide emission due to fossil fuel combustion consumption, and concerns about global warming due to this have been highlighted. Accordingly, non-petroleum resin materials such as polylactic acid have been actively developed and adopted in the material field as well as non-petroleum energy such as photovoltaic power generation.

  On the other hand, general-purpose condensation resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are used in a wide range of fields including parts such as packaging materials, optical materials, electrical and electronic equipment, and automobiles. These are condensation polymers made from petroleum-derived compounds, such as dicarboxylic acid compounds such as terephthalic acid and diol compounds. Recently, 1,3-propanediol, which is a non-petroleum diol, has been developed, and it has been actively used to use biomass raw materials that take environmental impact into consideration, such as adopting it as a resin raw material of this series. . However, for the dicarboxylic acid compound that is the other raw material, particularly terephthalic acid that is often used, since the synthesis starting material is paraxylene, which is a petroleum-derived raw material, Single-step synthesis of para-xylene from bio raw materials has been eagerly desired.

  On the other hand, conversion of non-petroleum compounds, that is, bio-based compounds into various synthetic synthons, is also actively studied using biochemical techniques such as enzymatic methods and artificial synthetic techniques. Of these, furan compounds that can be synthesized from sugar chain compounds such as glucose and fructose have recently attracted attention. Particularly noteworthy is the technology to convert glucose to hydroxymethylfurfural by hydrothermal treatment under pressure and the technology to obtain dimethylfuran through hydrogen reduction from it, and recently reported high yields. It was done. That is, since it has been shown that conversion of glucose to dimethylfuran can be performed with extremely high efficiency, it has been proposed to use this substance as a fuel.

Furthermore, another representative petroleum-based resin, polyethylene, has been attempted to synthesize ethylene, which is a raw material, from non-petroleum-based raw materials. In particular, active studies are underway to convert ethanol obtained by fermentation into ethylene by dehydration. Has been done.
Japanese Patent Laid-Open No. 2005-200321 JP-A-2005-232116 U.S. Pat. No. 4,828,603 SCIENCE vol.312, 1933 (2006) Nature vol.447, 982 (2007)

  An object of the present invention is to provide a method for producing paraxylene using 2,5-dimethylfuran and ethylene as raw materials.

  From the above situation, if para-xylene can be synthesized using 2,5-dimethylfuran and ethylene as starting materials, terephthalic acid can be synthesized from non-petroleum-derived raw materials. That means that a raw material of a general-purpose resin having a terephthalic acid structure such as PET can be converted from a petroleum material to a non-petroleum biomass material. Such technology has a tremendous effect on reducing environmental impact, and it can be said that it is an important technology that can greatly contribute to the construction of a sustainable social structure.

  In view of such a point, the present inventors, as a method of synthesizing para-xylene using 2,5-dimethylfuran as a raw material, used Diels-Alder reaction as shown in the following formula 1. Then, a method of dehydrating the obtained bicyclo compound as represented by the following formula 2 was devised.

  When an electron-withdrawing substituent is present in ethylene, which is a dienophile, Diels-Alder reaction can easily proceed in the presence of no catalyst or various catalysts (metal salts such as titanium, zirconium, hafnium, aluminum, zinc, etc.) Is widely known. However, there has been no report of a simple Diels-Alder reaction of ethylene with no substituent. The Diels-Alder reaction of ethylene without a substituent has a problem that it has a high activation energy and is difficult to proceed.

  As a result of intensive studies to solve the above problems, the present inventors have found that in the Diels-Alder reaction of 2,5-dimethylfuran and ethylene, (1) a high temperature is required to obtain a bicyclo compound as an addition product. It was confirmed that (2) the produced bicyclo compound was returned to the raw material again by the retro Diels-Alder reaction which was a reverse reaction under heating conditions. From these facts, in order to efficiently react the raw materials and obtain para-xylene, it was determined that it is important to promptly advance the next dehydration reaction, which is an irreversible reaction, and the present invention has been achieved.

  The present invention makes it possible to produce para-xylene using dimethylfuran and ethylene synthesized from glucose, which is a non-petroleum raw material, as raw materials. As a result, the raw material of petroleum-based general-purpose resin having a terephthalic acid structure could be converted into non-petroleum biomass material, and the technology that greatly contributed to the construction of a sustainable social structure could be established by its environmental impact reduction effect.

Hereinafter, the para-xylene manufacturing method of this invention is demonstrated concretely.
The para-xylene production method of the present invention uses 2,5-dimethylfuran (hereinafter abbreviated as DMF) and ethylene as raw materials and performs Diels-Alder reaction (hereinafter abbreviated as DA reaction) (the following formula 1). Then, the bicyclo compound (1) is obtained, and then the bicyclo compound (1) is subjected to a dehydration reaction (the following formula 2) to produce paraxylene.

  In the DA reaction of Formula 1, the feed ratio of ethylene and DMF (ethylene / DMF) as raw materials is preferably 1 or greater than 1. A charge ratio (ethylene / DMF) of greater than 1 means an excess of ethylene. However, since it is preferable that the recovered amount of excess ethylene after the reaction is small, a more preferable charging ratio is 1 or more and 50 or less, more preferably 1 or more and 10 or less. In the DA reaction of Formula 1, the progress of the reaction is greatly influenced by pressure because the boiling point of ethylene, which is one of the raw materials, is extremely low. For this reason, the DA reaction is preferably carried out by enclosing the raw materials in a sealed container or while continuously injecting the respective raw materials into the reaction tube. A preferable reaction temperature is 40 to 250 ° C, more preferably 80 to 200 ° C, and still more preferably 120 to 180 ° C. The reaction pressure depends on the amount of raw material charged and the reaction vessel volume when using a sealed container, and on the cross-sectional area and the liquid feed pressure of the raw material when using a reaction tube. In either case, the reaction pressure appropriately changes depending on the temperature and the volume of the container, but is preferably 1 atm or more and 100 atm or less.

  Further, the dehydration reaction of Formula 2 for converting the bicyclo compound (1) to paraxylene proceeds by allowing the bicyclo compound (1) to act on an organic condensing agent such as an inorganic salt, inorganic oxide, or carbodiimide having a dehydrating action. Can be made.

  Furthermore, it is also preferable to perform the DA reaction and the dehydration reaction in the same reaction vessel without isolating the bicyclo compound (1). That is, when performing the DA reaction, the bicyclo compound (1) can be isolated and purified by allowing an inorganic salt such as sodium sulfate or magnesium sulfate or a composite oxide such as silica / alumina to be present as a dehydration catalyst. The DA reaction and the dehydration reaction can be performed continuously, and the efficiency of the reaction can be improved. The dehydration catalyst used in this case is more preferably a composite oxide containing silica / alumina.

  The amount of the dehydration catalyst is preferably 0.1 mol% or more and 20 mol% or less with respect to DMF as a raw material.

  In order to further increase the efficiency of the reaction, a catalyst (DA catalyst) can also be used for the DA reaction. As the DA catalyst, metal salts such as titanium, zirconium, hafnium, aluminum, zinc, and antimony, complex compounds, and the like are preferably used. It is also preferable that the DA catalyst and the dehydration catalyst coexist.

  The amount of the DA catalyst is preferably 0.1 mol% or more and 10 mol% or less with respect to DMF as a raw material.

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Note that the confirmation of the product after the reaction (para xylene) and residual material using proton nuclear magnetic resonance ^{(1 H-NMR)} method.

Example Heat-resistant glass ampule for reaction (volume: 10 ml), DMF (molecular weight 96) 5 mmol (0.48 g), titanocene dichloride 0.05 mmol (12.5 mg), silica alumina composite oxide particles (particle size 0.1-5 μm) 81 mg: The silica-alumina composite oxide was filled with 0.6 mmol) with a molecular weight of 135, and purged with nitrogen, and then sealed with a rubber stopper with a glass cock. Subsequently, a balloon filled with ethylene gas was connected to the glass cock part, and the glass ampoule part was cooled with liquid nitrogen. After confirming that the gaseous ethylene had finished condensing in the ampule container, the cock was closed and the ampule was sealed. Subsequently, this ampoule was put into an oil bath heated to 180 ° C. for 3 hours for reaction. Thereafter, the ampule was taken out and the container was again cooled with liquid nitrogen, and then the ampule was opened. The opened ampoule was gradually heated to room temperature and the excess ethylene gas was removed by natural evaporation. The weight of the organic matter remaining in the ampoule was 0.51 g. It was confirmed that the main component of the organic substance was para-xylene ( ¹ H-NMR). As a result of quantification using the internal standard, the yield of paraxylene was 0.49 g.

  The present invention makes it possible to produce para-xylene using dimethylfuran and ethylene synthesized from glucose, which is a non-petroleum raw material, as raw materials. As a result, the raw material of petroleum-based general-purpose resin having a terephthalic acid structure could be converted into non-petroleum biomass material, and the technology that greatly contributed to the construction of a sustainable social structure could be established by its environmental impact reduction effect.

Claims (4)

A process for producing para-xylene using 2,5-dimethylfuran and ethylene as raw materials and comprising a Diels-Alder reaction represented by the following formula 1 and a dehydration reaction represented by the following formula 2 as steps.

The method for producing paraxylene according to claim 1, wherein the Diels-Alder reaction and the dehydration reaction are performed in the same reaction vessel. The method for producing paraxylene according to claim 1 or 2, wherein a catalyst is used for the dehydration reaction. The method for producing paraxylene according to claim 3, wherein the catalyst is a composite oxide containing silica / alumina.