KR101275370B1 - A method for producing diethylene glycol from ethylene oxide with high yield - Google Patents

Abstract

The present invention relates to a method of producing diethylene glycol in high yield by preparing a three-component mixed solution consisting of ethylene oxide, water, and monoethylene glycol, and hydrating it at a high temperature and high pressure. According to the present invention, the conversion from ethylene oxide to diethylene glycol is made with high selectivity, and the productivity of diethylene glycol can be greatly improved.

Description

A method for producing diethylene glycol from ethylene oxide with high yield}

The present invention relates to a method of producing diethylene glycol in high yield when ethylene oxide is hydrated in a liquid phase composed of water and ethylene glycol to obtain a glycol mixture product.

Diethylene glycol (hereinafter referred to as 'DEG') is a dehydrocondensation of two molecules of ethylene glycol (ethylene glycol or monoethylene glycol, hereinafter referred to as 'EG' or 'MEG') in ether form. When ethylene glycol is produced from ethylene oxide (hereinafter referred to as 'EO'), it is formed together as a by-product, and its use is gradually expanding. DEG is a colorless, odorless, viscous liquid, hygroscopic, blends well with saline, alcohol, ether, acetone, and ethylene glycol, and has the property of lowering the freezing point of water.

DEG is mainly used for plastics (alkyds, polyesters, polyurethanes, etc.), printing inks, adhesives for textiles, brake fluids, plasticizers, gas dehydrating agents, and cellophane softeners. The demand is steadily increasing, such as the use of water-soluble cutting oils used in the cutting of solar cell ingots and solar wafer cleaners as main components.

Such DEG commercially has no separate manufacturing method, and is mainly a by-product when preparing ethylene glycol (EG or MEG) from ethylene oxide.

Here ethylene glycol is commercially prepared, typically by the liquid phase hydration process of the corresponding ethylene oxide in the presence of a large molar excess of water [Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. 11, Third Edition, page 929 (1980).

Ethylene glycol is usually produced by a non-catalytic reaction between ethylene oxide and water, which generates 21.8 kcal of heat when 1 mole of EO reacts with 1 mole of water to produce 1 mole of MEG. . Thus, when the reaction is carried out as adiabatic reaction, the heat of reaction is absorbed by the reaction fluid in response to the temperature increase. The reaction temperature is usually at least 120 ° C. at the inlet of the reactor and exceeds 180 ° C. at the outlet.

Commercial processes focus on maximizing the conversion rate from EO to MEG. To this end, an excessive amount of water is supplied to EO for the purpose of suppressing side reactions. Typically, 20 mol or more of water is supplied to 1 mol of EO. As the amount of water increases, side reactions are suppressed and the MEG selectivity is increased.

When the feed ratio of EO: water, which is the most common process condition, is 1:22 in molar ratio, that is, 1: 9 in weight ratio, the selectivity by EO reaction is known as 88.5: 10.5: 0.5 for MEG: DEG: TEG. The distribution of MEG: DEG: TEG in the product is about 90% by weight, 9.5% by weight, and 0.5% by weight. In this situation, the supply of DEG depends on the demand and utilization rate of MEG, rather than the demand of DEG. As a result, supply is not keeping up with DEG demand, and MEG production needs to be increased to increase DEG production.

As described above, a method of generating DEG with high yield by increasing the rate of conversion from EO to DEG, that is, DEG generation selectivity, is not determined in conjunction with the production amount of DEG from EO, which is a raw material of DEG, and is determined. There is no known way so far. In particular, there is no known method for obtaining DEG in a high yield even when an excessive amount of water is used for EO under a catalyst-free reaction condition.

It is an object of the present invention to provide a method for increasing DEG productivity by producing DEG in high yield by increasing the selectivity for DEG production when the glycolene mixture is produced by non-catalyzed reaction of ethylene oxide in a liquid phase.

The present inventors have carefully studied the reaction kinetics of the reactor and the ethylene oxide in the conventional ethylene glycol production process and the reaction characteristics according to the reaction conditions, and surprisingly, in addition to the excess water, a considerable amount of co-solvent and co-solvents are added. By adding as a reactant to prepare a three-component solution consisting essentially of EO, water and MEG, and reacting it at high temperature and high pressure without a catalyst, it was found that selective conversion of EO to DEG was achieved at a high level not previously known. The present invention was completed.

Therefore, the present invention is to proceed the reaction of the three-component mixed solution of EO, water and MEG under a catalyst-free reaction substantially at high temperature and high pressure, so that high conversion selectivity of ethylene oxide (EO) to diethylene glycol (DEG) And a process for producing DEG from the EO in high yield.

In the present invention, the three-component mixed solution may be prepared by adding MEG to an aqueous solution of lean EO in which EO is dissolved in excess water, or by dissolving EO in a solution in which MEG is mixed with excess water. Alternatively, water, EO and MEG may each be introduced into the reaction separately. Regarding the phase of each of the above components as the reaction feed, each of EO, water and MEG can be supplied as a gas, as a liquid, or as a combination thereof.

The three-component mixed solution composed of EO, water, and MEG obtained by the above method is subjected to the reaction without substantially a catalyst under the reaction conditions of high temperature and high pressure to proceed with the hydration reaction of EO.

The EO used in the present invention may be pure EO or untreated EO containing a small amount of impurities, for example aldehydes.

In the present invention, the water used in the preparation of the three-component mixed solution may be derived from a wide variety of sources, and there is no need to satisfy special conditions with regard to purity. For example, in the process of chemical reactions involving fresh water, usually obtained from, for example, tap water, for example from tap water, or water treated by ion exchange processes, steam condensate and water removal reactions, in-process. The reaction water available can be used without limitation.

In the present invention, the water to be used is preferably provided in an excess amount compared to EO, and as long as it is provided in excess, the use ratio is not particularly limited. Preferably, the molar ratio of EO: water is 1:15 or more. More preferably, it is 1:20 or more. Preferably, the molar ratio is 1:40 or less, more preferably 1:35 or less, even more preferably 1:30 or less. If the molar ratio of water to EO is less than 15, it may interfere with the complete absorption of EO or stable liquid phase operation. The upper limit of the molar ratio of water to EO is not particularly limited, but if the amount of water is excessively excessive, excessive energy costs are generated during evaporation and distillation for water removal.

The MEG used in the present invention may be pure MEG or mixed with water and present in a mixed solution. In the case of a mixed solution with water, it is preferable to use a solution having a MEG concentration of 90% by weight or more. It may also be used to contain some impurities recovered by condensation after distillation in the reaction process.

The weight ratio of EO: MEG used in the present invention is preferably in the range of 1: 0.03 to 1:10, particularly preferably in the range of 1: 0.05 to 1: 5. If the weight ratio of EO: MEG is less than the above range, the effect of improving DEG selectivity is insufficient, and if it exceeds the above range, the reactor load is increased, and the energy cost of the separation and purification process after the reaction increases more than necessary, which is not preferable.

In the present invention, in the reaction of a three-component solution consisting substantially of EO, water and MEG at high temperature and high pressure without a catalyst, the reaction is typically carried out in two different types of commercial reactors, adiabatic and non-insulated reactors. Can be.

When the reaction is carried out in an adiabatic reactor, no heat is removed from the reactor. In this case, the temperature rise according to the reaction is controlled by supplying excess water so that heat is absorbed by the water supply. The adiabatic reactor is typically a cylindrical vessel or a tandem vessel with no heat transfer between the vessels and operates in a plug flow manner.

When the reaction is carried out in a non-insulated reactor, as the reaction proceeds, heat is removed from the reactor by transferring heat to the coolant. The feed of water and EO combined is then fed to a heat exchange reactor and once heat is formed it is immediately removed by a heat exchanger. Using suitable control and reactor designs, nearly isothermal conditions can be maintained and the reaction product is left at about the same temperature as the feed because the heat of reaction is removed by the coolant. Reactors most frequently used as such non-insulated type reactors include shell-and-tube heat exchangers (also called tubular or multitube type isothermal reactors or heat exchange reactors), where the reactions The mixture passes through several long narrow tubes and the coolant passes outside of the tubes.

Preferably, the reaction of the present invention is preferably carried out in adiabatic reaction, and the reaction heat generated by the reaction of the present invention is absorbed by the reaction fluid in response to the temperature increase.

"Insulation" means that no substantial transfer of heat occurs into or out of the reactor system. Thus, the reactor system may comprise a heat exchanger where it is used to exchange heat in the reactor feed and product stream, thereby transferring heat to the surroundings, or transferring heat to an external process stream or external device, Or no heat transfer from them occurs and all of the heat in the reaction mixture is preserved.

The reaction in the present invention is preferably performed at a high temperature because the reaction rate is maximized and the selectivity is not affected by the high temperature. A further advantage of the high temperature operation is that there is a reduction in the need to provide an external source of heat to the downstream purification apparatus to separate and recover the unreacted water from the reaction product.

Specifically, the reaction temperature is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, even more preferably 120 ° C. or higher at the inlet when using an adiabatic reactor. The outlet temperature is preferably controlled by controlling the temperature to 250 ° C or lower, more preferably 230 ° C or lower, even more preferably 210 ° C or lower.

In the present invention, the pressure range of the reaction is generally from 100 to 10000 kPa, preferably from 500 to about 5000 kPa, with the intention of avoiding vapor formation.

According to the present invention, a three-component mixed solution composed of EO, water, and MEG is prepared, and EO is hydrated (or hydrolyzed) to increase the ratio (conversion selectivity) converted from EO to DEG to improve reaction selectivity. So that DEG can be produced in high yield. In this way, DEG productivity can be greatly increased without increasing the MEG production to increase DEG production.

Hereinafter, the present invention will be described in detail, and the present invention will be described in detail through examples for showing some advantages that can be achieved when using the present invention. However, the following examples are presented for illustrative purposes, and the present invention is not limited by these examples.

Example

In the following examples, 'EO conversion rate', 'DEG selectivity', 'MEG selectivity' and 'DEG yield' are defined as follows.

EO conversion rate: (moles of EO consumed by the reaction) / (moles of EO introduced into the reaction) x 100

DEG selectivity: (number of moles of EO consumed in the generation of DNA) / (number of moles of EO added to the reaction) x 100 = (number of moles of DEG generated) x 2 / (number of moles of EO added to the reaction) x 100

MEG selectivity: (moles of EO consumed to generate MEG) / (moles of EO introduced into the reaction) x 100 = (moles of generated MEG) / (moles of EO introduced into the reaction) x 100

DEG yield: EO conversion rate x DEG selectivity

Example  One

The reactor used a stainless steel double jacketed tube reactor 1 M high and 3/8 inch inside diameter jacketed. The heat transfer fluid was connected to a thermostat to keep the reaction temperature constant while circulating through the jacket. A thermocouple thermometer and a pressure gauge were installed on the reactor outlet side to measure the temperature and the reaction pressure of the reaction product.

Pure monoethylene glycol was added to the aqueous ethylene oxide solution to prepare a homogeneous three-component mixed solution while stirring, and the reaction feed stream was fed to the reactor inlet side at a constant flow rate using a quantitative pump. The reactor was operated at 17.4 bar to prevent steam formation. The reactor temperature was maintained at 150 ° C.

The composition of each component in the three-component mixed solution (reaction feed) of EO, water, and MEG was 9.68%: 87.15%: 3.17% (1: 9: 0.327) by weight ratio of EO: water: MEG, respectively. The feed rate of the reactants to the reactor was 4 ml / min.

The product was analyzed by gas chromatograph for ethylene oxide (EO), monoethylene glycol (MEG), diethylene glycol (DEG) and triethylene glycol (TEG). Molar selectivity was calculated by dividing the number of moles of EO consumed to form a given product by the total number of moles of EO converted to all products. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was less than 85.0 mol%, 14.0 mol% and 1.0 mol%, respectively.

Example  2

The same procedure as in Example 1 was conducted except that the weight ratio of EO: water: MEG in the three-component mixed solution of EO, water, and MEG was 1: 9: 0.827. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was less than 82.2 mol%, 16.8 mol% and 1.0 mol%, respectively.

Example 3

The same procedure as in Example 1 was conducted except that the weight ratio of EO: water: MEG in the three-component mixed solution of EO, water, and MEG was 1: 9: 1.327. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was less than 79.6 mol%, 19.3 mol% and 1.0 mol%, respectively.

Example 4

The same procedure as in Example 1 was conducted except that the weight ratio of EO: water: MEG in the three-component mixed solution of EO, water, and MEG was 1: 9: 1.907. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was less than 76.6 mol%, 22.3 mol% and 1.107 mol%, respectively.

The results of the above Examples 1 to 4 are summarized in Table 1 below.

Example 5

The same procedure as in Example 1 was conducted except that the weight ratio of EO: water: MEG in the three-component mixed solution of EO, water, and MEG was 1: 10.23: 0.3298. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was less than 85.3 mol%, 13.7 mol% and 1.05 mol%, respectively.

Example 6

The same procedure as in Example 1 was conducted except that the weight ratio of EO: water: MEG in the three-component mixed solution of EO, water, and MEG was 1: 10.23: 1.3298. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was 78.8 mol%, 20.0 mol% and 1.23 mol%, respectively.

Example 7

The same procedure as in Example 1 was conducted except that the weight ratio of EO: water: MEG in the three-component mixed solution of EO, water, and MEG was 1: 10.23: 3.3298. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was 67.4 mol%, 31.1 mol% and 1.61 mol%, respectively.

Example 8

The same procedure as in Example 1 was conducted except that the weight ratio of EO: water: MEG in the three-component mixed solution of EO, water, and MEG was 1: 10.23: 4.3298. EO conversion was 100 mol%, selectivity to MEG, DEG and TEG was 63.3 mol%, 35.1 mol% and 1.64 mol%, respectively.

The results of the above Examples 5 to 8 are summarized in Table 2 below.

As can be seen from Table 1 and Table 2, according to the method of the present invention, the selectivity of conversion from ethylene oxide to diethylene glycol can be remarkably increased to 10% or more, thereby significantly increasing the productivity of diethylene glycol. Can be improved.

Claims (8)

In preparing an ethylene glycol mixture by hydration of ethylene oxide, the method comprises hydrating a three-component mixed solution composed of ethylene oxide, water, and monoethylene glycol, wherein the molar ratio of ethylene oxide: water is 1:15 to 1 :: A method of improving the yield of diethylene glycol in the ethylene glycol mixture by setting the amount to 40 and hydrating the weight ratio of ethylene oxide: monoethylene glycol to 1: 0.03 to 1:10. The method of claim 1, wherein the three-component mixed solution is prepared by adding monoethylene glycol to an aqueous solution of ethylene oxide in which ethylene oxide is dissolved in water, or dissolving ethylene oxide in a solution in which monoethylene glycol is mixed in water. Method for improving the yield of diethylene glycol, characterized in that. The method for improving the yield of diethylene glycol according to claim 1 or 2, wherein the hydration reaction is carried out in an adiabatic reactor. The method of claim 3, wherein the hydration reaction is carried out in a non-catalytic reaction. delete The method for improving the yield of diethylene glycol according to claim 1, wherein the hydration reaction temperature is 80 to 250 ° C and the reaction pressure is 100 to 10000 kPa. The method of claim 6, wherein the molar ratio of ethylene oxide: water is 1:20 to 1:30, the hydration reaction temperature is 100 to 250 ° C, and the reaction pressure is 500 to 5000 kPa. Way. 8. The method according to claim 7, wherein the weight ratio of ethylene oxide: monoethylene glycol is 1: 0.05 to 1: 5.