JP2010030902A - Method for producing ethylene - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing high purity ethylene at high conversion and a high yield by dehydration of ethanol. <P>SOLUTION: The method for producing ethylene is characterized by maintaining moisture contained in ethanol to be fed as a raw material, at 0.1 wt.% or higher. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing high-purity ethylene at a high conversion rate by a dehydration reaction of ethanol.

  Ethylene is a useful compound as a raw material for various low-molecular compounds and high-molecular compounds. In particular, naphtha cracker-derived materials are used as raw materials for various polymers. On the other hand, a decrease in petroleum resources has been sought in the past, and in recent years, various production of ethylene from raw materials derived from coal, natural gas or biomass has been studied from the viewpoint of environmental problems.

  Among them, a method for producing ethylene by dehydration of a lower alcohol such as methanol or ethanol or a lower aliphatic ether such as dimethyl ether is expected as a relatively simple and useful production method.

However, even if it is merely a dehydration reaction of alcohol, it is a very difficult technique to produce ethylene with high conversion and high yield. Patent Document 1 and Patent Document 2 are patents (applications) relating to a method for producing a lower olefin by a dehydration reaction of alcohol, but in the examples, methanol is used as a raw material alcohol, and the resulting olefin also has a small ethylene content. Not expensive. Patent Document 3 is a patent application regarding a method for producing ethylene by dehydration reaction of ethanol, but although the conversion rate is relatively high, it cannot be said that the amount of other olefins produced is small, and therefore the yield is satisfactory. It wasn't going to be good.
JP 58-146516 A US Pat. No. 5,914,433 JP-A-1-233236

  An object of the present invention is to find a method for producing high-purity ethylene at a high conversion rate in a high yield using ethanol as a raw material.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that high-purity ethylene can be obtained at a high conversion rate and a high yield by adjusting the amount of water contained in the raw material ethanol. .

That is, the present invention is as follows.
[1] A method for producing ethylene by dehydration reaction of ethanol, characterized in that water in the supplied water-containing ethanol is 0.1 wt% or more,
[2] The method for producing ethylene according to [1], wherein the temperature of the dehydration reaction is 250 ° C. or higher, and
[3] The method for producing ethylene according to [1], wherein the water-containing ethanol is biomass-derived ethanol.

According to the method of the present invention, even in the dehydration reaction of ethanol, high-purity ethylene can be produced at a high conversion and high yield, and high-quality ethylene can be produced significantly and economically. I can do it. In addition, if a material derived from biomass is used as the raw material ethanol, it is extremely useful in terms of carbon dioxide balance in the environment, and its contribution to the global environment is tremendous also as a derivative or polymer thereof.

  The present invention is described in detail below.

  The ethanol used as a raw material in the present invention may be any ethanol such as synthetic ethanol derived from naphtha and fermented ethanol derived from biomass.

  Biomass-derived fermented ethanol refers to ethanol that has been purified by bringing a microorganism or ethanol-derived product from ethanol into contact with a culture solution containing a carbon source obtained from a plant. For purification of ethanol from the culture solution, conventionally known techniques such as distillation, membrane separation, extraction, etc. can be applied, but benzene, cyclohexane, etc. are added and azeotroped, or moisture is removed by membrane separation, etc. The method of removing etc. is mentioned.

  In order to obtain ethylene of the present invention, it is not industrially efficient to carry out further refinement (for example, the total amount of impurities in ethanol is 1 ppm or less) at this stage, but this is denied. is not.

  When ethylene is obtained by a dehydration reaction of ethanol, a catalyst is usually used. However, this catalyst is not particularly limited, and a known catalyst can be used. A process advantage is a fixed bed flow reaction in which the catalyst and the product can be easily separated. For example, γ-alumina is desirable, but other known catalysts may be used.

  Since this dehydration reaction is an endothermic reaction, it is usually carried out under heating conditions. The reaction is not particularly limited as long as the reaction proceeds at a commercially useful reaction rate, but a temperature of 100 ° C. or higher, preferably 250 ° C. or higher, more preferably 300 ° C. or higher is appropriate. The upper limit is not particularly limited, but is 500 ° C. or less, preferably 400 ° C. or less, in terms of energy balance and equipment.

  The reaction pressure is not particularly limited, but a pressure higher than normal pressure is preferable in order to facilitate subsequent gas-liquid separation. Industrially, a fixed bed flow reaction in which the catalyst is easily separated is suitable, but a liquid phase suspension bed, a fluidized bed, etc. may be used.

  In the present invention, the most important is the amount of water contained in ethanol supplied as a raw material. Generally, when performing a dehydration reaction, it is preferable that there is no water in view of water removal efficiency. However, in the case of ethanol dehydration reaction using a solid catalyst, it has been found that in the absence of water, the production of other olefins, particularly butene, tends to increase. It is presumed that ethylene dimerization after dehydration cannot be suppressed unless a small amount of water is present. The lower limit of the allowable water content is at least 0.1%, preferably 0.5% or more. The upper limit is not particularly limited, but is 50% by weight or less, preferably 30% or less, more preferably 20% or less, on the mass balance and heat balance.

  By performing a dehydration reaction of ethanol in this way, a mixed part of ethylene, water and a small amount of unreacted ethanol is obtained. Since ethylene is a gas at a temperature of about 5 MPa or less at normal temperature, gas and liquid separation is performed from these mixed parts. Ethylene can be obtained except water and ethanol. This method may be performed by a known method.

  The ethylene obtained by gas-liquid separation is further distilled, and there are no particular restrictions on the distillation method, operating temperature, residence time, etc., except that the operating pressure at this time is normal pressure or higher.

  When the raw material is biomass-derived ethanol, the resulting ethylene contains carbonyl compounds such as ketones, aldehydes and esters, which are impurities mixed in the ethanol fermentation process, and carbon dioxide, which is a decomposition product thereof, as well as enzyme decomposition products and today. It contains trace amounts of nitrogen-containing compounds such as amines and amino acids that are miscellaneous substances and ammonia that is a decomposition product thereof. Depending on the use of ethylene, these trace amounts of impurities may cause a problem and may be removed by purification. Purification may be carried out by any known method, but as a suitable purification operation, an adsorption purification method can be mentioned. Although the adsorbent to be used is not particularly limited, a material having a high surface area is preferable, and the type of adsorbent is selected according to the type and amount of impurities in ethylene obtained by dehydration reaction of biomass-derived ethanol.

  Note that a caustic water treatment may be used in combination as a method for purifying impurities in ethylene. In the case of performing caustic water treatment, it is desirable to perform it before adsorption purification. In that case, it is necessary to perform a water removal treatment after the caustic treatment and before the adsorption purification.

  The fact that ethylene obtained by the method of the present invention or a polymer such as polypropylene produced using ethylene as a raw material uses a biomass raw material means that the content of carbon of mass 14 and mass of 12 or mass 13 It can be determined by measuring the carbon content.

  Specifically, ASTM D6866 04 (Standard Test Method for Determining the Biobased Content of Natural Range Material RandomMandop is used as a sample of the Random Material Society of Radiocarbon and IS And put the accurately quantified CO2 gas into an AMS (Accelerated Mass Spectrometry) device to measure the mass number 14, and the mass number 12 or mass number 13 carbon mass, and the mass number present in the atmosphere or petrochemicals. It can be determined by comparing with the abundance of 14 carbons.

  In addition, the sample is burned, and the obtained CO2 is absorbed with a CO2 absorbent or converted into benzene, and the amount of carbon having a mass number of 14 is measured with a liquid scintillation counter and compared with that derived from petroleum. You can also.

  Examples of the present invention will be described below, but the present invention is not limited by these.

[Example 1]
In the middle of a stainless steel vertical reactor having an inner diameter of 3.8 mm (3/16 inch) and a length of 200 mm, 100 mg of a granular material pulverized from commercially available γ-alumina and sized to 250 to 500 μm was packed. After the air in the reactor was replaced with argon, the reactor was heated.
When the reactor reached 360 ° C., industrial ethanol containing 8% water was supplied from the top of the reactor at a rate of 0.15 ml / hr.
As the reaction proceeded, a liquid product containing water as the main component and a gas product containing ethylene as the main component were obtained. The reaction was continued for one week, and the obtained liquid product and gas product were analyzed by gas chromatography, respectively.

[Example 2]
The reaction was carried out in the same manner as in Example 1 except that ethanol derived from distilled and purified biomass containing 8% water was used as a raw material. The results are shown in Table 1.

[Comparative Example 1]
The reaction was carried out in the same manner as in Example 1 except that reagent ethanol (Aldrich, water content: less than 0.1 wt%) was used as a raw material. The results are shown in Table 1.

  The production method of the present invention is very useful in terms of process and economy because it can produce ethylene with high conversion and high purity in high yield. Moreover, since ethylene purity is high, it is particularly useful for adjusting the supply and demand balance of lower olefins. Furthermore, the use of biomass-derived ethanol as a raw material is extremely useful in terms of carbon dioxide balance in the environment, and its derivative or polymer contributes greatly to the global environment.

Claims (3)

In the method for producing ethylene by dehydration reaction of ethanol, the water in the supplied water-containing ethanol is 0.1 wt% or more, and the method for producing ethylene is characterized in that The method for producing ethylene according to claim 1, wherein the temperature of the dehydration reaction is 250 ° C or higher. The method for producing ethylene according to claim 1, wherein the hydrous ethanol is biomass-derived ethanol.