Process for purifying an alkylene oxide composition

Abstract

A process for purifying an alkylene oxide composition comprising: (1) obtaining a crude alkylene oxide composition comprising an ionic component; (2) passing the crude alkylene oxide composition through a molecular sieve, wherein the pore size of the molecular sieve is greater than 2.3 Å to less than 10 Å; and (3) obtaining a purified alkylene oxide composition, wherein the crude alkylene oxide composition in the above step (1) has a CPR of 0.2 to 20 and a N content of 0.2 to 10 ppm, and where the ionic component NH 4 + and the content of NH 4 + in the crude alkylene oxide composition in step (1) is 0.1 to 5 ppm and wherein the purified alkylene oxide composition has a N content of 0.1 to 5 ppm and the NH content 4 +in the purified alkylene oxide composition is 0.05 to 2.5 ppm.

Description

Field of expertise

[0001] Embodiments relate to a method for purifying an alkylene oxide composition by removing an ionic component formed during the production of an alkylene oxide. Technical background of the invention

[0002] Alkylene oxides are used as important intermediates in the chemical industry. Alkylene oxides are produced by various processes. Depending on the reactants, catalysts, solvents, and the like used, various byproducts can be formed.

[0003] For example, propylene oxide is mainly produced by the hydrochlorination route and the dual production process (i.e., a process for producing a styrene monomer or methyl tert-butyl ether together with propylene oxide). However, the hydrochlorination route is increasingly being avoided due to contamination concerns. The dual production process also involves difficulties in rebuilding or expanding facilities due to the limited usability of byproducts. Thus, studies on new processes for producing propylene oxide have been conducted in recent years.

[0004] According to a new production process, propylene is epoxidized using hydrogen peroxide as the oxidizing agent under the action of a titanium compound as a catalyst, producing a propylene oxide composition. This production process is advantageous in that it is simple, has low energy consumption, and is environmentally friendly.

[0005] However, this process is disadvantageous in that the resulting propylene oxide composition contains an impurity that may affect a subsequent process for producing a polyol or the like. Thus, studies have continued on what type of impurities are formed and how to selectively remove these impurities.

[0006] DE 696 16 895 T2 describes a process for the epoxidation of an olefin, comprising reacting the olefin with hydrogen peroxide in a liquid phase in said reaction zone in the presence of a titanium-containing molecular sieve catalyst, a basic salt comprising an anionic species and a cation selected from ammonium cations, alkali metal cations and alkaline earth metal cations, and an amount of a chelating agent effective to reduce the non-selective decomposition of the hydrogen peroxide to molecular oxygen upon aging of the titanium-containing molecular sieve catalyst.

[0007] JP 2003160573 A describes propylene oxide which is separated from the raw material stream by contacting the raw material stream, which consists of propylene oxide and contains at least one impurity from the group consisting of water, methanol, acetaldehyde, propionaldehyde, acetone and methyl formate, with the porous zeolite.

[0008] CN 106117165 A describes a process for the purification of propylene oxide, which comprises the following steps: In a fixed-bed reactor, liquid-phase propylene oxide containing aldehyde impurities enters the reaction bed of the fixed-bed reactor from the bottom up. The modified zeolite molecular sieve in the reaction bed has a temperature of 5 to 60°C, 0.3. The aldehyde impurities in the propylene oxide are adsorbed under the condition of ~10.0 MPa to obtain purified propylene oxide. The modified zeolite molecular sieve adsorbing the aldehyde impurities is subjected to high-temperature purging with an inert gas, and the aldehyde substance is recovered. Modified zeolite molecular sieve restores the adsorption performance. The volumetric space velocity (LHSV) of the propylene oxide containing aldehyde impurities entering the reaction bed of the fixed-bed reactor is 0.1 to 30 h-1.

[0009] DE 600 06 503 T2 describes a process for purifying propylene oxide contaminated with poly(propylene oxide), which process comprises the following steps: (a) contacting the liquid propylene oxide with an adsorbent consisting of magnesium silicate and / or calcium silicate under conditions such that the amount of poly(propylene oxide) is reduced to the desired extent, and (b) recovering the purified propylene oxide product.

[0010] A molecular sieve (or molecular sieve for short) is the functional name for natural and synthetic zeolites or other materials that have a high adsorption capacity for gases, vapors, and dissolved substances of specific molecular sizes. By choosing the right molecular sieve, it is possible to separate molecules of different sizes. In addition to zeolites, there are also carbon molecular sieves (carbon molecular sieves or molecular sieving carbon). While these are somewhat more expensive due to the process, they can also be specialized for a specific separation during pyrolysis. Disclosure of the inventionTechnical problem to be solved

[0011] Embodiments aim to provide a purified alkylene oxide composition suitable for a subsequent process by selectively removing an ionic component unnecessary for the subsequent process from the by-products of alkylene oxide produced by the novel process. Solution to the problem

[0012] The process for purifying an alkylene oxide composition according to one embodiment comprises (1) obtaining a crude alkylene oxide composition comprising an ionic component; (2) passing the crude alkylene oxide composition through a molecular sieve; and (3) obtaining a purified alkylene oxide composition.

[0013] The subject matter of the present invention is set forth in the independent claims. Preferred embodiments of the invention are set forth in the dependent claims. Advantageous effects of the invention

[0014] According to the method for purifying an alkylene oxide composition according to the embodiments, a purified alkylene oxide composition suitable for a subsequent process can be obtained. Detailed description of the implementation of the invention

[0015] Hereinafter, the present invention will be described in detail with reference to the embodiments. The embodiments are not limited to those described below, but can be modified into various forms as long as the gist of the invention is not changed.

[0016] When this description refers to a part as “comprising” an element, it should be understood that the part may also comprise other elements.

[0017] Furthermore, all numbers and expressions used herein relating to amounts of components, reaction conditions and the like are to be understood as modified by the term "about" unless otherwise indicated.

[0018] Embodiments aim to provide a purified alkylene oxide composition suitable for subsequent processing.

[0019] The process for purifying an alkylene oxide composition according to one embodiment comprises (1) obtaining a crude alkylene oxide composition comprising an ionic component; (2) passing the crude alkylene oxide composition through a molecular sieve; and (3) obtaining a purified alkylene oxide composition.

[0020] To purify an alkylene oxide composition according to one embodiment, a crude alkylene oxide composition comprising an ionic component is first obtained (step (1)).

[0021] "Crude alkylene oxide composition" refers to a composition immediately after it has been produced by a process for producing an alkylene oxide. The composition includes an ionic component or the like that is not necessary for a subsequent process.

[0022] The crude alkylene oxide composition may comprise an alkylene oxide, an ionic component, a nonionic component, and a solvent.

[0023] The crude alkylene oxide composition includes an ionic component.

[0024] The ionic component may comprise a cationic component and an anionic component.

[0025] In particular, the cationic component may be at least one selected from the group consisting of NH 2 + , NH 4 +and molecular sieves that contain these as a functional group. For example, the cationic component can be NH 4 + As another example, the cationic component may be NH 2 + and NH 4 + For example, the cationic component can consist of NH 4 + exist, but is not limited to.

[0026] The ionic component includes NH 4 + , and the content of NH 4 + in the crude alkylene oxide composition is 0.1 to 5 ppm. In particular, the ionic component comprises NH 4 + , and the content of NH 4 + in the crude alkylene oxide composition is 0.1 to 3 ppm, 0.1 to 2.5 ppm, 0.3 to 2 ppm, or 0.5 to 1.5 ppm, but is not limited thereto.

[0027] Furthermore, the anionic component may be at least one selected from the group consisting of NO 2 - , NO 3 - and molecular sieves that contain these as a functional group. For example, the anionic component NO 2 - As another example, the anionic component NO 2 - and NO 3 - For example, the anionic component may consist of NO 2 - exist, but are not limited to.

[0028] The ionic component includes NO 2 - , and the NO content 2 - in the crude alkylene oxide composition is 0.1 to 5 ppm. The ionic component includes NO 2 - , and the NO content 2 -in the crude alkylene oxide composition is, but is not limited to, 0.1 to 3 ppm, 0.1 to 1 ppm, or 0.25 to 0.75 ppm.

[0029] The ionic component may comprise a nitrogen-containing ionic component.

[0030] For example, the ionic component may comprise at least one selected from the group consisting of NH 2 + , NH 4 + , NO 2 - and NO 3 - Alternatively, the ionic component may also consist of at least one selected from the group consisting of NH 2 + , NH 4 + , NO 2 - and NO 3 - consists.

[0031] The ionic component comprises 30 to 90 wt.% of the cationic component, based on the total weight of the ionic component. In particular, the ionic component may comprise 40 to 90 wt.%, 50 to 90 wt.%, or 50 to 80 wt.% of the cationic component, based on the total weight of the ionic component. In particular, the ionic component may comprise 60 to 80 wt.% of the cationic component, based on the total weight of the ionic component, but is not limited thereto.

[0032] The crude alkylene oxide composition may comprise a non-ionic component in addition to the ionic component.

[0033] For example, the nonionic component may comprise an amine-based component.

[0034] In particular, the amine-based component may comprise at least one selected from the group consisting of diisopropylamine, diethylamine, trimethylamine, diethanolamine, dimethylethylamine, methyldiethanolamine and monoisopropylamine.

[0035] In addition, the crude alkylene oxide composition may also comprise a solvent.

[0036] In particular, the solvent may comprise at least one selected from the group consisting of water, methanol, acetaldehyde, propionaldehyde, methyl formate and dimethoxymethane.

[0037] For example, the crude alkylene oxide composition may include dimethoxymethane (DMM) and methyl formate (MF). The content of dimethoxymethane (DMM) and methyl formate (MF) may be, but is not limited to, 10 to 3000 ppm, 10 to 1000 ppm, 10 to 500 ppm, or 20 to 100 ppm.

[0038] The crude alkylene oxide composition in the above step (1) has a controlled polymerization rate (CPR) of 0.2 to 20. Specifically, the crude alkylene oxide composition may have a controlled polymerization rate (CPR) of 0.2 to 10, 0.2 to 5, 0.2 to 2, 0.5 to 3, 0.5 to 2, or 0.8 to 1.5, but is not limited thereto.

[0039] "Controlled Polymerization Rate (CPR)" refers to an index indicating the amount of a basic substance in an alkylene oxide composition. It is a value measured according to the ASTM D6437 test method, in which 30 g of an alkylene oxide composition is mixed with 100 ml of methanol and the amount of hydrochloric acid (concentration: 0.001 N) required for neutralization titration is measured.

[0040] If the CPR of the crude alkylene oxide composition in the above step (1) is outside the above range, it is difficult to control the reactivity in the production of a downstream product using it as a raw material, and the CPR value of the thus-produced product will not fall within the CPR requirement for that product. Thus, the CPR of the crude alkylene oxide composition must be maintained within the above range.

[0041] In particular, it is more advantageous to keep the CPR value of the crude alkylene oxide composition at 2.0 or less to the maximum.

[0042] In particular, since the amount of cationic impurities in the ionic impurities is larger than that of anionic impurities, the cationic impurities remaining after neutralization of the impurities may be a factor increasing the CPR value of the crude alkylene oxide composition.

[0043] The crude alkylene oxide composition in the above step (1) has a basicity of 1 to 40. Specifically, the crude alkylene oxide composition may have a basicity of 2 to 40, 2 to 20, 0.4 to 10, or 0.4 to 7, but is not limited thereto.

[0044] In particular, since the amount of cationic impurities in the ionic impurities is larger than that of anionic impurities, the cationic impurities remaining after neutralization of the impurities may be a factor increasing the basicity of the crude alkylene oxide composition.

[0045] The crude alkylene oxide composition in the above step (1) has an N content of 0.2 to 10 ppm. More specifically, the crude alkylene oxide composition has an N content of 0.2 to 7 ppm, 0.2 to 5 ppm, 0.2 to 3 ppm, or 0.2 to 2 ppm. In particular, the crude alkylene oxide composition may have an N content of 0.5 to 1.8 ppm, 1.0 to 1.8 ppm, or 1.2 to 1.8 ppm, but is not limited thereto.

[0046] If the N content in the crude alkylene oxide composition is kept high in the above step (1), it may cause a foul odor in the downstream product in which it is used as a raw material. Thus, the N content in the crude alkylene oxide composition is preferably kept as low as possible.

[0047] The factors that increase the N content in the crude alkylene oxide composition are the components containing N in the ionic component, the non-ionic component and the solvent described above.

[0048] The alkylene oxide may be ethylene oxide, propylene oxide, butylene oxide, or the like. In particular, the alkylene oxide may be propylene oxide.

[0049] The crude alkylene oxide composition may be passed through a bead section after step (1) and before the following step (2).

[0050] The bead section comprises a plurality of beads having an average diameter of 1 to 5 mm. In particular, the bead section may comprise, but is not limited to, a plurality of beads having an average diameter of 1.5 to 4 mm or 2 to 3 mm.

[0051] The number of beads contained in the bead section per unit volume is 100 to 100,000 / liter. In particular, the number of beads contained in the bead section per unit volume may be, but is not limited to, 1,000 to 80,000 / liter, 5,000 to 70,000 / liter, 10,000 to 50,000 / liter, or 15,000 to 40,000 / liter.

[0052] In addition, the space velocity at which the crude alkylene oxide composition is passed through the bead section is greater than 0 to 10 h -1 . In particular, the space velocity at which the crude alkylene oxide composition is passed through the bead section may be 0.2 to 5 h -1 , 0.2 to 3 hours -1 , 0.2 to 2 hours -1 , 0.5 to 2 hours -1 or 0.8 to 1.5 hours -1 but is not limited to.

[0053] The beads contained in the bead section may comprise an inactive material consisting of silicalite as a raw material.

[0054] The bead section serves to induce a uniform dispersion of the crude alkylene oxide composition before it is passed to a downstream molecular sieve.

[0055] Then, the crude alkylene oxide composition is passed through a molecular sieve (step (2)).

[0056] The molecular sieve may be a zeolite-based molecular sieve. In particular, the molecular sieve may have a structure selected from the group consisting of zeolite A, zeolite X, zeolite beta, zeolite Y, zeolite L, and ZSM-12.

[0057] “Molecular sieve” refers collectively to silicoaluminas, and these may be in an octagonal geometric structure having an inlet of fine holes composed of rings of oxygen atoms, intersecting with other holes curved at regular intervals between the holes, but are not limited to this.

[0058] In such a case, the pore size of the molecular sieve is greater than 2.3 Å to less than 10 Å. Specifically, the pore size of the molecular sieve may be, but is not limited to, 3 Å to less than 10 Å, 3 Å to 7.5 Å, 3 Å to 5 Å, 3.5 Å to 4.5 Å, 3.8 Å to 4.2 Å, or 3.9 Å to 4.1 Å.

[0059] In addition, the shape of the pores of the molecular sieve can be octagonal. In particular, the molecular sieve has octagonal micropores, and commercially available products have a spherical shape of about 2 mm, with molecular sieves physically combined with each other.

[0060] The molecular sieve can selectively adsorb impurities smaller than the octagonal micropores. Alternatively, the negative charge (i.e., acid point) of the zeolite-series molecular sieve itself can adsorb the cationic component present in the crude alkylene oxide composition.

[0061] The space velocity at which the crude alkylene oxide composition is passed through the molecular sieve is greater than 0 to 10 h -1 . In particular, the space velocity at which the crude alkylene oxide composition is passed through the molecular sieve can be 0.2 to 5 h -1 , 0.2 to 3 hours -1 , 0.2 to 2 hours -1, 0.5 to 2 hours -1 or 0.8 to 1.5 hours -1 but is not limited to.

[0062] Then, a purified alkylene oxide composition is obtained (step (3)).

[0063] The purified alkylene oxide composition comprises an ionic component comprising a cationic component and an anionic component.

[0064] In such a case, the nature of the ionic component is as described in step (1) above.

[0065] Furthermore, the purified alkylene oxide composition may comprise, in addition to the ionic component, a nonionic component and a solvent. They are as described in step (1) above.

[0066] When the purified alkylene oxide composition comprises an ionic component comprising a cationic component and an anionic component, the ionic component comprises 10 to 70 wt.% of the cationic component based on the total weight of the ionic component. More preferably, the ionic component comprises, but is not limited to, 20 to 70 wt.%, 30 to 70 wt.%, 40 to 60 wt.%, or 45 to 55 wt.% of the cationic component based on the total weight of the ionic component.

[0067] For example, the purified alkylene oxide composition comprises NH 4 + , and the content of NH 4 + in the purified alkylene oxide composition is 0.05 to 2.5 ppm. In particular, the content of NH 4 +in the purified alkylene oxide composition may be, but is not limited to, 0.1 to 2 ppm, 0.1 to 1 ppm, 0.2 to 0.8 ppm, 0.2 to 0.6 ppm, or 0.4 to 0.6 ppm.

[0068] That is, a significant amount of the cationic component, such as NH 4 + present in the crude alkylene oxide composition can be removed when the composition is passed through the molecular sieve.

[0069] In addition, the purified alkylene oxide composition comprises NO 2 - , and the NO content 2 - in the purified alkylene oxide composition is 0.1 to 5 ppm. In particular, the content of NO 2 - in the purified alkylene oxide composition may be, but is not limited to, 0.1 to 3 ppm or 0.25 to 0.75 ppm.

[0070] The purified alkylene oxide composition in the above step (3) has a CPR of 0 to 2. Specifically, the purified alkylene oxide composition may have a CPR of 0 to 1.5, 0 to 1.2, 0 to 0.8, 0 to 0.5, 0.1 to 0.5, 0.1 to 0.3, or 0.1 to 0.2, but is not limited thereto.

[0071] The definition of CPR is as described in step (1) above.

[0072] When the CPR of the purified alkylene oxide composition in the above step (3) is within the above range, it is advantageous in that the reactivity can be easily controlled in the production of a downstream product using the same as a raw material, and the low CPR value of the thus-produced product satisfies the CPR requirement for that product.

[0073] The purified alkylene oxide composition in the above step (3) has a basicity of 0 to 4. In particular, the purified alkylene oxide composition may have a basicity of 0 to 3, 0 to 2.4, 0 to 1.6, or 0 to 1.0, but is not limited thereto.

[0074] The purified alkylene oxide composition in the above step (3) has an N content of 0.1 to 5 ppm. Specifically, the purified alkylene oxide composition may have an N content of 0.1 to 3 ppm, 0.1 to 2 ppm, 0.2 to 1.5 ppm, or 0.4 to 1.1 ppm, but is not limited thereto.

[0075] When the content of N in the purified alkylene oxide composition in the above step (3) is within the above range, it is advantageous in that the malodor in the downstream product using the same as a raw material is reduced to a level of the malodor in the downstream product using alkylene oxide produced by other processes such as the hydrochlorination route process and the dual production process.

[0076] The present invention will now be explained in detail with reference to examples. However, the following examples are intended to further illustrate the present invention, and the scope of the examples is not limited thereto. ExamplesExample 1

[0077] A crude alkylene oxide composition was obtained by a process for producing an alkylene oxide. In such a case, the crude compositions thus obtained contained NH 4 + , NO 2 - and alkylene oxide.

[0078] 100 g of the crude alkylene oxide composition were heated at a space velocity of 1 h -1 through a container containing 8 liters (about 6 kg) of a molecular sieve having an average diameter of about 2 mm and an average pore size of about 4 Å in a number per unit volume of about 20,000 / liter, to thereby obtain a purified alkylene oxide composition. Comparison example 1

[0079] The same procedure as in Example 1 was repeated except that the pore size of the molecular sieve was 10 Å. Comparison example 2

[0080] The same procedure as in Example 1 was repeated except that the pore size of the molecular sieve was 2.3 Å. Valuation examples

[0081] The properties and post-processing results of the alkylene oxide compositions purified by the purification methods of Example 1 and Comparative Examples 1 and 2 were evaluated. The results are shown in Table 1 below. Evaluation example 1: Measurement of the NH content 4 +

[0082] According to the test method of ASTM D 6919 (Standard Test Method for Determination of Dissolved Cations in Water by Ion Chromatography), 2 g of the composition to be measured was diluted with ultra-high purity water, and NH 4 + was quantitatively analyzed by an ion chromatography analyzer. Evaluation example 2: Measurement of NO content 2 -

[0083] According to the test method of ASTM D 4327 (Standard Test Method for Anions in Water by Suppressed Ion Chromatography), 2 g of the composition to be measured was diluted with ultra-high purity water, and NO 2 - was quantitatively analyzed by an ion chromatography analyzer. Assessment example 3: Measurement of CPR

[0084] According to the test method of ASTM D 6437 (Standard Test Method for Polyurethane Raw Materials), 30 g of the composition to be measured was mixed with 100 ml of methanol, followed by neutralization titration with 0.001 N hydrochloric acid to calculate the amount of hydrochloric acid consumed. Evaluation example 4: Measurement of the N content

[0085] According to the test method of ASTM D 4629 (Standard Test Method for Trace Nitrogen in Liquid Hydrocarbons), 1 g of the composition to be measured was diluted with a high-purity solvent combusted in an oxygen and argon state to detect the wavelengths emitted by excited nitrogen dioxide for quantitative analysis. Table 1 Example 1 Comparison Example 1 Comparison Example 2 Crude alkylene oxide composition Content in NH 4 + 1.05 ppm 1.05 ppm 1.05 ppm NO content 2 - 0.55 ppm 0.55 ppm 0.55 ppm CPR value 1,0 1,0 1,0 N content 1.6 ppm 1.6 ppm 1.6 ppm Purified alkylene oxide composition Content in NH 4 + 0.55 ppm Reaction terminated due to an exothermic reaction 1.05 ppm NO content 2 - 0.55 ppm 0.55 ppm CPR value 0,1 1,0 N content 1.1 ppm 1.6 ppm

[0086] As can be seen from Table 1 above, the improvement rate in CPR was 90% or more, and the reduction rate in N content was 30% or more in Example 1 compared with Comparative Examples 1 and 2. In particular, the test in Comparative Example 1 could not be performed because an exothermic reaction occurred, and the CPR and N content were not improved in Comparative Example 2.

Claims

[1] A process for purifying an alkylene oxide composition comprising: (1) obtaining a crude alkylene oxide composition comprising an ionic component; (2) passing the crude alkylene oxide composition through a molecular sieve, wherein the pore size of the molecular sieve is greater than 2.3 Å to less than 10 Å; and (3) obtaining a purified alkylene oxide composition, wherein the crude alkylene oxide composition in the above step (1) has a CPR of 0.2 to 20 and a N content of 0.2 to 10 ppm, and where the ionic component NH4 + and the content of NH4 + in the crude alkylene oxide composition in step (1) is 0.1 to 5 ppm and wherein the purified alkylene oxide composition has a N content of 0.1 to 5 ppm and the NH4 content + in the purified alkylene oxide composition is 0.05 to 2.5 ppm. [2] A process for purifying an alkylene oxide composition according to claim 1, wherein the ionic component is NH4 + and an anionic component. [3] A process for purifying an alkylene oxide composition according to claim 1, wherein the ionic component contains 30 to 90 wt% NH4 + based on the total weight of the ionic component. [4] A process for purifying an alkylene oxide composition according to claim 1, wherein the molecular sieve has a structure selected from the group consisting of zeolite A, zeolite X, zeolite beta, zeolite Y, zeolite L and ZSM-12. [5] A process for purifying an alkylene oxide composition according to claim 1, wherein the alkylene oxide is propylene oxide. [6] A process for purifying an alkylene oxide composition according to claim 1, wherein the space velocity at which the crude alkylene oxide composition is passed through the molecular sieve is greater than 0 to 10 h -1 is. [7] A process for purifying an alkylene oxide composition according to claim 1, wherein the crude alkylene oxide composition is passed through a bead section after step (1) and before the following step (2); the bead section comprises a plurality of beads having an average diameter of 1 to 5 mm; and the number of beads contained in the bead section per unit volume is 100 to 100,000 / litre. [8] A process for purifying an alkylene oxide composition according to claim 1, wherein the purified alkylene oxide composition comprises an ionic component containing NH4 + and an anionic component; and the ionic component 10 to 70 wt.% NH4 + based on the total weight of the ionic component. [9] A process for purifying an alkylene oxide composition according to claim 1, wherein the purified alkylene oxide composition has a CPR of 0 to 2.