Process for the preparation of OME2

Abstract

The invention relates to a process for the preparation of H3C-O-(CH2O) 2-CH3 (OME2), comprising the following steps: introducing a reactant composition comprising methylal and one or more polyoxymethylene dimethyl ethers having the formula H3C-O-(CH2O) n-CH3, 3 < = n < = 20 (OME3-20) into a reactor and converting it into a product mixture comprising OME2, methylal and one or more polyoxymethylene dimethyl ethers OME3-20, introducing the product mixture into a distillation unit D1 and separating the product mixture into a first fraction, which contains methylal and leaves the distillation unit D1 as an overhead stream KSD1, and a second fraction, which contains OME2 and one or more polyoxymethylene dimethyl ethers OME3-20 and leaves the distillation unit D1 as a bottom stream SSD1, -introducing the bottom stream SSD1 into the distillation unit D2 and separating the bottom stream SSD1 into a first fraction comprising OME2 and leaving the distillation unit D2 as an overhead stream KSD2 and into a second fraction comprising one or more polyoxymethylene dimethyl ethers OME3-20 and leaving the distillation unit D2 as a bottom stream SSD2.

Description

Background Technology

[0001] It has the formula H3C-O-(CH2O) n Polyoxymethylene dimethyl ether (also known as polyoxymethylene dimethyl ether or polyoxymethylene dimethyl ether) with -CH3 (n≥3) groups, especially those with 3 to 5 formaldehyde units (OME). 3-5 Polyoxymethylene dimethyl ether (POM) has attracted considerable attention as a synthetic diesel fuel or as a diesel fuel additive; however, OME2, a compound with the formula H3C-O-(CH2O)2-CH3 (CAS No.: 628-90-0), is not well-suited for such applications due to its low flash point.

[0002] On the other hand, OME2 has attracted considerable attention as a solvent, for example as a solvent for paints, varnishes, oils and rubber, as a possible additive for gasoline and as a formaldehyde absorbent, see, for example, Z. Xue et al., “The Study on the application of Low Polymerization degree PODE2”, AIP Conference Proceedings 1839, 020017 (2017), and WO 2016 / 180085 A1.

[0003] In the synthesis of polyoxymethylene dimethyl ether, a formaldehyde source (e.g., formaldehyde, trioxymethylene, or paraoxymethylene) and a compound for methyl-termining (such as methanol, methyl acetal, or dimethyl ether) are typically used as reactants. If the reaction mixture contains methanol and water, these substances react with formaldehyde according to the following reaction equations 1 through 4 to form polyoxymethylene glycol (MG). n ;HO-(CH2O) n -H) and polyoxymethylene hemiacetal (HF) n ;HO-(CH2O) n These reactions do not require the presence of a catalyst and they reach chemical equilibrium very quickly. In most cases, chemical equilibrium is also on the product side, and therefore the product mixture contains virtually no monomeric formaldehyde (CH2O). To form methyl acetal (H3C-O-(CH2O)1-CH3;OME1) via acetalization between methanol and HO-CH2O-CH3 (HF1) according to the following reaction equation 5, the presence of an acidic catalyst is required. Chain growth via the insertion of additional CH2O units occurs according to the following reaction equation 7. Methanol with polyoxymethylene hemiacetal HF nThe additional acetalization reaction occurs according to the following reaction equation 6. Possible side reactions for the formation of trioxymethylene ((CH2O)3) and methyl formate (HC(O)OCH3) are shown in the following reaction equations 8 and 9.

[0004]

[0005] For n≥2 (OME) ≥2 ), especially n=3 to 5 (OME) 3-5 Polyoxymethylene dimethyl ether (H3C-O-(CH2O)) n An overview of known production methods for CH3 is presented, for example, in publications such as F. Mantei et al., Sustainable Energy & Fuels, 2022, Vol. 6, pp. 528–549. The text distinguishes between non-aqueous and aqueous synthetic routes. Anhydrous synthetic routes result in fewer byproducts, but providing reactants is energy-intensive. Providing reactants for aqueous synthetic routes is less energy-intensive, but the reaction products include other byproducts and water.

[0006] Methyl acetal and trioxymethylene are examples of reactants used in the non-aqueous phase synthesis of polyoxymethylene dimethyl ether. The product stream obtained using this synthetic method typically still contains a large amount of unreacted trioxymethylene. Because the flash points of trioxymethylene (115°C) and OME2 (105°C) are very close, efficient separation of OME2 by distillation is very difficult.

[0007] In aqueous synthetic routes for the production of polyoxymethylene dimethyl ether (OME2), an aqueous solution containing formaldehyde and methanol is used as a reactant, for example. The product stream obtained using this synthetic method typically contains water and possibly polyoxymethylene glycol. Because the flash points of these substances overlap with those of OME2, efficient separation of OME2 by distillation using aqueous synthetic routes is also very difficult.

[0008] CN 106397142 A describes a method for producing OME2, wherein methyl acetal and trioxymethylene are used as reactants, and the reaction is carried out in the presence of zeolite as a catalyst.

[0009] CN 107522602 A describes a method for producing OME2, wherein methyl acetal, methanol, and water are reacted in a reactive distillation unit.

[0010] CN 104292085 A describes a method for producing polyoxymethylene dimethyl ether, wherein methanol or methyl acetal is oxidized to formaldehyde, formaldehyde is polymerized to form paraoxymethylene, paraoxymethylene and methyl acetal are reacted to produce polyoxymethylene dimethyl ether, and these polyoxymethylene dimethyl ethers are separated into OME2 and OME. 3-4 .

[0011] CN 105152882 A describes a method for producing OME 3-5 The method in which methyl acetal and OME are made ≥6 They react with each other as reactants. Summary of the Invention

[0012] The object of this invention is to prepare OME2 via an efficient (e.g., energy-saving) method that can provide OME2 with high purity.

[0013] This objective is achieved using a method for producing a compound having the formula H3C-O-(CH2O)2-CH3(OME2), the method comprising the following steps:

[0014] - Contains methyl acetal (OME1) and one or more compounds having the formula H3C-O-(CH2O) n The reactant composition Z of polyoxymethylene dimethyl ether with -CH3 (3≤n≤20) R The reactants are introduced into reactor R1 and reacted in the presence of an acidic catalyst to obtain a product comprising H3C-O-(CH2O)2-CH3 (OME2), methyl acetal (OME1), and one or more substances having the formula H3C-O-(CH2O). n Z, a mixture of products of polyoxymethylene dimethyl ether with -CH3 (3≤n≤20) P ,

[0015] - The product mixture Z P The product mixture Z is introduced into distillation unit D1 and distilled. P The sample is separated into a first fraction and a second fraction. The first fraction contains methyl acetal (OME1) and is the top stream KS. D1 Leaving the distillation unit D1, the second fraction comprises H3C-O-(CH2O)2-CH3(OME2) and one or more compounds having the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether and as the bottom stream SS D1 Leaving the distillation unit D1,

[0016] -The bottom flow SS D1 The bottom stream SS is introduced into distillation unit D2 and distilled.D1 Separate into a first fraction and a second fraction, the first fraction containing H3C-O-(CH2O)2-CH3(OME2) and serving as the top stream KS D2 Leaving the distillation unit D2, the second fraction contains one or more components having the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether and as the bottom stream SS D2 It leaves the distillation unit D2.

[0017] In reactant composition Z R It uses methyl acetal and has the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether as a reactant leads to product composition Z P It contains only very low concentrations of undesirable byproducts such as formaldehyde, water, methanol, polyoxymethylene glycol, and polyoxymethylene hemiacetal, or even none at all. Apart from OME2, the product composition Z... P It also contains methyl acetal and one or more compounds having the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether. Product composition Z P The methyl acetal present in it and the H3C-O-(CH2O) group... n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether can be a reactant composition Z R Unreacted reactants in reactor R1, or reactants that can be reformed during the reaction in reactor R1.

[0018] Regarding the yield or purity of OME2, if OME2 and a compound having the formula H3C-O-(CH2O) are mixed in the first distillation unit D1... n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether (as bottom stream SS) D1 ) are separated together by distillation, and then OME2 is distilled with these having the formula H3C-O-(CH2O) in distillation unit D2. n Separating polyoxymethylene dimethyl ether of -CH3 (3≤n≤20) has also proven advantageous within the scope of this invention.

[0019] Reactant composition Z R Preferably, it contains reactants (i.e., methylal and one or more having the formula H3C-O-(CH2O)) at a total concentration of at least 90% by mass, more preferably at least 95% by mass, and still more preferably at least 98% by mass. n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether.

[0020] Reactant composition Z R For example, it is free of formaldehyde, methanol, and / or non-aqueous, or contains formaldehyde, methanol, and water in a total concentration of less than 5% by mass, preferably less than 0.5% by mass.

[0021] In an exemplary embodiment, in reactant composition Z R The substance present in it has the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether has a mass average molecular weight M in the range of 136 g / mol to 210 g / mol. W .

[0022] Those skilled in the art know how to determine the composition of a mixture containing multiple components (in this case, a mixture with the formula H3C-O-(CH2O)). n The mass average molecular weight of a mixture of polyoxymethylene dimethyl ethers with the formula H3C-O-(CH2O) is relative to the molecular weight of the polyoxymethylene dimethyl ether mixture with the formula H3C-O-(CH2O). n The total mass of polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O) is determined by identifying each of the following in the reactant composition: -CH3 (3≤n≤20). n The relative mass fractions of polyoxymethylene dimethyl ether (POM) with -CH3 (3 ≤ n ≤ 20) are calculated and multiplied by their molar mass. The sum of these values ​​yields the formula H3C-O-(CH2O). n The mass average molecular weight M of polyoxymethylene dimethyl ether with -CH3 (3≤n≤20) is W The mass average molecular weight M can be adjusted by using the corresponding relative mass fraction of polyoxymethylene dimethyl ether. W .

[0023] For example, in reactant composition Z R The presence of at least 80% or at least 90% by mass of the substance having the formula H3C-O-(CH2O) n Among polyoxymethylene dimethyl ethers with the formula H3C-O-(CH2O), one or more are of the formula H3C-O-(CH2O). n -CH3 (3≤n≤10) polyoxymethylene dimethyl ether.

[0024] For example, in reactant composition Z R The presence of at least 50% by mass (e.g., 50 to 90% by mass) of the substance having the formula H3C-O-(CH2O) n Polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O) is one or more types of polyoxymethylene dimethyl ethers with the formula H3C-O-(CH2O). n -CH3 (3≤n≤5) polyoxymethylene dimethyl ether.

[0025] In another exemplary embodiment, the reactant composition Z R The methyl acetal and one or more polyoxymethylene dimethyl ethers in the mixture have a mass average molecular weight in the range of 90 g / mol to 190 g / mol, more preferably in the range of 90 g / mol to 136 g / mol, or in the range of 100 g / mol to 120 g / mol. This results in an additional increase in the yield of OME2 during the reaction of the reactants in reactor R1.

[0026] As previously noted, those skilled in the art know the use of mixtures of multiple components (in this case, methyl acetal and having the formula H3C-O-(CH2O)) for extraction. n A method for determining the mass-average molecular weight in a mixture of polyoxymethylene dimethyl ethers (CH3, 3 ≤ n ≤ 20) with the formula H3C-O-(CH2O). The method involves determining the mass-average molecular weight of the methyl acetal and each polyoxymethylene dimethyl ether present in the reactant composition relative to the total mass of the methyl acetal and polyoxymethylene dimethyl ether. n The relative mass fractions of polyoxymethylene dimethyl ether (POM) with the formula H3C-O-(CH2O) were calculated and multiplied by their molar mass. The sum of these values ​​yielded the methyl acetal and the polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O). n The mass average molecular weight M of a mixture of polyoxymethylene dimethyl ethers with -CH3 (3≤n≤20) W The mass average molecular weight M can be adjusted by the relative mass fractions of methyl acetal and the corresponding polyoxymethylene dimethyl ether. W .

[0027] The reactants in the reactant composition can be introduced into reactor R1 individually. Alternatively, the reactants can be mixed together outside reactor R1, and then the mixture can be fed into reactor R1.

[0028] In an exemplary embodiment, reactant composition Z R At least a portion of the polyoxymethylene dimethyl ether is prepared in a separate production unit and then fed into reactor R1 (either without intermediate storage or optionally after temporary intermediate storage).

[0029] Those skilled in the art will know that it is suitable for making methyl acetal and having the formula H3C-O-(CH2O). n The conditions for the reaction of polyoxymethylene dimethyl ether with -CH3 (3≤n≤20) to generate OME2 can be defined, or these conditions can be easily defined based on general technical knowledge.

[0030] The reaction occurs in the presence of an acidic catalyst. Those skilled in the art know of suitable acidic catalysts. Solid catalysts or liquid acids can be used. The following is a list of catalysts that can be used: ion exchange resins containing acidic groups (i.e., cation exchange resins), zeolites, aluminosilicates, alumina, transition metal oxides (optionally present on a support material), graphene oxide, mineral acids (e.g., sulfuric acid), organic acids (e.g., sulfonic acid), acidic ionic liquids, and oxonium salts (e.g., trimethyloxonium salt).

[0031] Reactor R1 operates, for example, at a pressure of 1 to 10 bar and a temperature of 20 to 120°C. The pressure and temperature are preferably selected such that the reactant composition Z... R The reaction in reactor R1 is at least partially in the liquid phase. Reactor R1 is, for example, a fixed-bed reactor. However, within the scope of this invention, other types of reactors may also be used for the purpose of reacting the reactant composition.

[0032] As previously noted, in reactant composition Z R It uses methyl acetal and has the formula H3C-O-(CH2O). n Polyoxymethylene dimethyl ether with -CH3 (3≤n≤20) as a reactant has the effect of not forming or forming only at low concentrations undesirable byproducts such as formaldehyde, water, methanol, polyoxymethylene glycol and polyoxymethylene hemiacetal during the reaction.

[0033] For example, product mixture Z P It contains OME2, methyl acetal, and one or more substances having the formula H3C-O-(CH2O). n The polyoxymethylene dimethyl ether of -CH3 (3≤n≤20) has a total concentration of at least 90% by mass, more preferably at least 95% by mass, and still more preferably at least 99% by mass.

[0034] For example, the product mixture Z formed in reactor R1 P It contains OME2 at a concentration of at least 5% by mass, more preferably at least 10% by mass, such as 5 to 40% by mass or 10 to 35% by mass.

[0035] For example, in product mixture Z P The presence of at least 80% or at least 90% by mass of the substance having the formula H3C-O-(CH2O) n Polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O) is one or more types of polyoxymethylene dimethyl ethers with the formula H3C-O-(CH2O). n -CH3 (3≤n≤10) polyoxymethylene dimethyl ether.

[0036] For example, in product mixture Z PThe presence of at least 45% by mass (e.g., 45 to 90% by mass) of the substance having the formula H3C-O-(CH2O) n Polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O) is one or more types of polyoxymethylene dimethyl ethers with the formula H3C-O-(CH2O). n -CH3 (3≤n≤5) polyoxymethylene dimethyl ether.

[0037] The product mixture Z, as will be described in more detail below. P The feed is introduced into distillation unit D1. Before being fed into distillation unit D1, the product mixture Z... P It can be achieved through a unit containing alkaline materials and / or filters. The alkaline materials can be used to neutralize the product mixture. P The filter unit can remove any acidic catalyst residues that may be present in the product mixture, and it can also remove any residues that may be dispersed in the product mixture. P The solid in it.

[0038] Product mixture Z P The product mixture Z is introduced into distillation unit D1 and distilled to obtain the product mixture Z. P Separation into a first fraction and a second fraction, the first fraction containing methyl acetal and serving as the top stream KS D1 Leaving distillation unit D1, this second fraction contains OME2 and one or more compounds having the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether and as the bottom stream SS D1 Leave distillation unit D1.

[0039] Therefore, distillation unit D1 is configured to separate the product mixture Z by distillation in the following manner. P Methyl acetal is extracted from distillation unit D1 as a top stream, and OME2 and one or more having the formula H3C-O-(CH2O) n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether is extracted as a bottom stream. Those skilled in the art can determine suitable conditions for this based on general technical knowledge. Distillation unit D1, for example, is a distillation column. A distillation unit typically comprises devices for separation by distillation as well known to those skilled in the art, particularly trays, packed bodies, or structured packing. Distillation unit D1 preferably does not contain any catalyst (especially not an acidic catalyst). Distillation unit D1 is preferably not a reactive distillation unit. For example, distillation unit D1 operates at a pressure of 1 to 5 bar and a temperature of 40 to 200°C.

[0040] For example, the top stream KS leaving distillation unit D1 D1It contains methylal at a concentration of at least 60% by mass, more preferably at least 90% by mass, and even more preferably at least 99% by mass.

[0041] The top stream KS leaving distillation unit D1 D1 At least a portion of it can be returned to reactor R1 so that the topflow KS D1 The methyl acetal contained therein can act as a reactant in reactor R1.

[0042] For example, the bottom stream SS exiting distillation unit D1 D1 It contains OME2 at a total concentration of at least 80% by mass, more preferably at least 95% by mass, and one or more having the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether.

[0043] For example, the bottom stream SS exiting distillation unit D1 D1 It contains OME2 at a concentration of at least 15% by mass, for example, from 15% to 90% by mass.

[0044] For example, in the bottom flow SS D1 The presence of at least 80% or at least 90% by mass of the substance having the formula H3C-O-(CH2O) n Polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O) is one or more types of polyoxymethylene dimethyl ethers with the formula H3C-O-(CH2O). n -CH3 (3≤n≤10) polyoxymethylene dimethyl ether.

[0045] For example, in the bottom flow SS D1 The presence of at least 45% by mass (e.g., 45 to 90% by mass) of the substance having the formula H3C-O-(CH2O) n Polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O) is one or more types of polyoxymethylene dimethyl ethers with the formula H3C-O-(CH2O). n -CH3 (3≤n≤5) polyoxymethylene dimethyl ether.

[0046] The bottom stream SS leaving distillation unit D1 D1 The feed is fed into distillation unit D2, and the bottom stream SS is distilled. D1 The fraction is separated into a first fraction and a second fraction, the first fraction containing OME2 and serving as the top stream KS. D2 Leaving distillation unit D2, this second fraction contains one or more components having the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether and as the bottom stream SS D2 Leave distillation unit D2.

[0047] Therefore, regarding bottom flow SS D1 Through distillation separation, distillation unit D2 is configured such that OME2 exits distillation unit D2 as a top stream, and one or more having the formula H3C-O-(CH2O). n The polyoxymethylene dimethyl ether (POM) of -CH3 (3≤n≤20) exits distillation unit D2 as a bottom stream. Those skilled in the art can determine suitable conditions for this based on general technical knowledge. Distillation unit D2 is, for example, a distillation column. A distillation unit typically comprises devices for separation by distillation as well known to those skilled in the art, particularly trays, packed bodies, or structured packing. Distillation unit D2 preferably does not contain a catalyst (especially not an acidic catalyst). Distillation unit D2 is preferably not a reactive distillation unit. For example, distillation unit D2 operates at a pressure of 0.5 to 3 bar and a temperature of 50 to 220°C.

[0048] As previously noted, it has been found that if OME2 and have the formula H3C-O-(CH2O) n -CH3 (3≤n≤10) polyoxymethylene dimethyl ether (as bottom stream SS) D1 If OME2 is separated together by distillation in the first distillation unit D1, and then separated from the polyoxymethylene dimethyl ether by distillation in the distillation unit D2, this is advantageous in terms of the yield and purity of OME2 within the scope of the invention.

[0049] For example, the top stream KS leaving distillation unit D2 D2 It contains OME2 at a concentration of at least 75% by mass, more preferably at least 95% by mass.

[0050] For example, the bottom stream SS leaving distillation unit D2 D2 At least a portion can be returned to reactor R1 so that the bottom flow SS D2 The substance present in it has the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether can act as a reactant in reactor R1.

[0051] As previously noted, reactant composition Z R The polyoxymethylene dimethyl ether can be produced at least partially in a separate production unit and subsequently fed into reactor R1 (either without intermediate storage or optionally after temporary intermediate storage). In this exemplary embodiment, the top stream KS exiting distillation unit D1... D1 and / or the bottom stream SS exiting distillation unit D2 D2 It may be advantageous to return at least a portion of the material to the individual production unit. This step is intended to improve thermal integration. Detailed Implementation

[0052] The following text will refer to Figure 1 Exemplary embodiments of the method according to the present invention will be described in more detail.

[0053] One or more of the formula H3C-O-(CH2O) are supplied via pipeline 1. n A polyoxymethylene ether of -CH3 (3≤n≤20) and methylal supplied via line 2 are fed as reactant compositions into reactor R1 via line 3. Figure 1 in, “OME 3-20 "Represents one or more having the formula H3C-O-(CH2O) n -CH3 (3≤n≤20) polyoxymethylene ether, and “OME1” represents methyl acetal.

[0054] In reactor R1, the reactants react in the presence of an acidic catalyst to obtain H3C-O-(CH2O)2-CH3 ( Figure 1 The "OME2" in the formula, methyl acetal, and one or more compounds with the formula H3C-O-(CH2O) n A mixture of products of polyoxymethylene ethers with -CH3 (3≤n≤20).

[0055] The product mixture obtained in reactor R1 is fed into distillation unit D1 via line 4. In distillation unit D1, it is separated by distillation into a fraction containing methyl acetal and exiting distillation unit D1 as a top stream via line 5, and a fraction containing OME2 and one or more of the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene ether and as the bottom stream flowing through line 6 out of distillation unit D1.

[0056] The topstream exiting distillation unit D1 via line 5 is returned to reactor R1 so that the methyl acetal contained in the topstream can act as a reactant in reactor R1. If one or more of the reactant compositions contain the formula H3C-O-(CH2O)... n The polyoxymethylene ether of -CH3 (3≤n≤20) is produced in a separate production unit and subsequently introduced via line 1, so that at least a portion of the top stream leaving distillation unit D1 via line 5 can be fed into the separate production unit. Figure 1 (Not shown in the image).

[0057] The bottom stream exiting distillation unit D1 via line 6 is fed into distillation unit D2. In distillation unit D2, it is separated by distillation into a fraction containing OME2 and exiting distillation unit D2 as a top stream via line 7, and a fraction containing one or more components having the formula H3C-O-(CH2O).n The polyoxymethylene ether with the formula -CH3 (3≤n≤20) is a fraction that exits distillation unit D2 as a bottom stream via line 8. The bottom stream exiting distillation unit D2 via line 8 is returned to reactor R1 so that the fraction containing the formula H3C-O-(CH2O) is present in the bottom stream. n -CH3 (3≤n≤20) polyoxymethylene ethers can function as reactants in reactor R1. If the polyoxymethylene ether in the reactant composition is prepared in a separate production unit and subsequently supplied via line 1, then at least a portion of the bottom stream exiting distillation unit D2 via line 8 can be fed into that separate production unit. Figure 1 (Not shown in the image).

[0058] In an alternative embodiment, this objective is achieved by a method for producing a compound having the formula H3C-O-(CH2O)2-CH3(OME2), the method comprising the following steps:

[0059] - Contains methyl acetal (OME1) and one or more compounds having the formula H3C-O-(CH2O) n The reactant composition Z of polyoxymethylene dimethyl ether with -CH3 (3≤n≤20) R The reactants are introduced into reactor R1 and reacted in the presence of an acidic catalyst to obtain a product containing H3C-O-(CH2O)2-CH3 (OME2), methyl acetal (OME1), and one or more substances having the formula H3C-O-(CH2O). n Z, a mixture of products of polyoxymethylene dimethyl ether with -CH3 (3≤n≤20) P ,

[0060] - Mix the product mixture Z P The product mixture Z is introduced into distillation unit D1 and distilled to obtain the product mixture Z. P The mixture is separated into a first fraction and a second fraction. The first fraction contains methyl acetal (OME1) and H3C-O-(CH2O)2-CH3 (OME2), and the second fraction contains one or more compounds having the formula H3C-O-(CH2O). n -CH3 (3≤n≤20) polyoxymethylene dimethyl ether,

[0061] - The first fraction of distillation unit D1 is separated into stream S containing at least 50% by mass of methyl acetal. OME1 And a stream S containing at least 50% by mass of H3C-O-(CH2O)2-CH3(OME2) OME2 .

[0062] Regarding reactant composition Z R For its properties, please refer to the explanation given above.

[0063] For information on suitable conditions for operating reactor R1, please refer to the previous description.

[0064] For information on suitable acidic catalysts for the reaction of reactants in reactor R1, please refer to the previous description.

[0065] The distillation unit D1 is operated in a manner that separates the distillate into a first fraction and a second fraction. The first fraction contains methyl acetal (OME1) and H3C-O-(CH2O)2-CH3 (OME2), and the second fraction contains one or more components having the formula H3C-O-(CH2O). n Polyoxymethylene dimethyl ether with the formula H3C-O-(CH2O) can be determined by those skilled in the art based on general technical knowledge. n The second fraction of polyoxymethylene dimethyl ether containing -CH3 (3≤n≤20) was used as the bottom stream SS. D1 Leave distillation unit D1.

[0066] The first fraction from distillation unit D1 is separated into stream S containing at least 50% by mass of methyl acetal. OME1 And a stream S containing at least 50% by mass of H3C-O-(CH2O)2-CH3(OME2) OME2 This can be carried out, for example, in a condenser and / or an additional distillation unit D2. For example, the first fraction is taken as the top stream KS. D1 The distillation unit D1 exits, and the top stream KS... D1 It is separated into stream S in the condenser and / or additional distillation unit D2. OME1 and S OME2 .

[0067] Example

[0068] The simulated examples described below demonstrate that the method according to the invention can efficiently and with high purity produce the compound H3C-O-(CH2O)2-CH3(OME2). These simulated examples are based on... Figure 1The illustrated system includes reactor R1 and distillation units D1 and D2. Simulations of the embodiments were performed using the principles of the software and methods described in the following publication: F. Mantei, O. Salem, R. Ali, A. Schaadt et al., “Techno-economic assessment and carbon footprint of processes for the large-scale production of oxymethylenedimethyl ethers from carbon dioxide and hydrogen,” Sustainable Energy Fuels, 2022, Vol. 6, p. 528.

[0069] A flow having the following composition is supplied via pipeline 1:

[0070] OME3: 50% by weight

[0071] OME4: 33% by weight

[0072] OME5: 17% by weight

[0073] Methylal (OME1) is supplied via line 2.

[0074] The methylal is returned via line 5 as the top stream leaving distillation unit D1, and the OME is returned via line 8 as the bottom stream leaving distillation unit D2. 3-10 .

[0075] The flows from these pipelines 1, 2, 5, and 8 are mixed with each other; thus, reactant composition Z is obtained. R It is fed into reactor R1 via pipeline 3.

[0076] Reactant composition Z R It has the following components:

[0077] OME1: 26% by weight

[0078] OME3: 20% by weight

[0079] OME4: 16% by weight

[0080] OME5: 12% by weight

[0081] OME6:8% by weight

[0082] OME7: 6% by weight

[0083] OME8: 5% by weight

[0084] OME9: 4% by weight

[0085] OME 10 3% by mass

[0086] Reactor R1 is a fixed-bed reactor that operates at a pressure of 1 bar and a temperature of 50°C. Amberlyst 46 (an ion exchange resin containing sulfonic acid groups) is used as the acid catalyst.

[0087] The product mixture Z exits reactor R1 via pipeline 4 and is fed into distillation unit D1. P It has the following components:

[0088] OME1: 18% by weight

[0089] OME2: 17% by weight

[0090] OME3: 15% by weight

[0091] OME4: 13% by weight

[0092] OME5: 11% by weight

[0093] OME6:8% by weight

[0094] OME7: 6% by weight

[0095] OME8: 5% by weight

[0096] OME9: 4% by weight

[0097] OME 10 3% by mass

[0098] In distillation unit D1, the product mixture Z P The KS stream, containing methyl acetal, was separated by distillation and served as the top stream. D1 The fraction leaving distillation unit D1, and containing OME2 and OME. 3-10 And as the bottom flow SS D1 The fraction exiting distillation unit D1. Top stream temperature and pressure: 42°C, 1 bar. Bottom stream temperature and pressure: 141°C, 1 bar.

[0099] Top Stream KS D1 Composition:

[0100] OME1: 100% by weight

[0101] Bottom Stream SS D1 Composition

[0102] OME2: 21% by weight

[0103] OME3: 19% by weight

[0104] OME4: 16% by weight

[0105] OME5: 13% by weight

[0106] OME6: 10% by weight

[0107] OME7:8 mass percentage

[0108] OME8: 6% by weight

[0109] OME9: 4% by weight

[0110] OME 10 3% by mass

[0111] Bottom Stream SS D1 The feed is introduced into distillation unit D2 via line 6. In distillation unit D2, it is separated by distillation into a stream containing OME2, which is then distributed as the top stream KS. D2 The fraction leaving distillation unit D2, and containing OME 3-10 And as the bottom flow SS D2 The fraction exiting distillation unit D2. Top stream temperature and pressure: 104°C, 1 bar. Bottom stream temperature and pressure: 191°C, 1 bar.

[0112] Top Stream KS D2 Composition:

[0113] OME2: 100% by weight

[0114] Bottom Stream SS D2 Composition

[0115] OME3: 23% by weight

[0116] OME4: 20% by weight

[0117] OME5: 16% by weight

[0118] OME6: 13% by weight

[0119] OME7: 10% by weight

[0120] OME8: 8% by weight

[0121] OME9: 6% by weight

[0122] OME 10 4% by mass

[0123] This embodiment demonstrates that the method according to the invention can efficiently and with high purity produce the compound H3C-O-(CH2O)2-CH3(OME2) (see the top stream KS exiting distillation unit D2). D2 It is basically composed of OME2.

Claims

1. A method for producing H3C-O-(CH2O)2-CH3, comprising the following steps: - Contains methyl acetal and one or more compounds having the formula H3C-O-(CH2O) n The reactant composition Z of polyoxymethylene dimethyl ether with -CH3, 3≤n≤20 R The reactants are introduced into reactor R1 and reacted in the presence of an acidic catalyst to obtain a mixture comprising H3C-O-(CH2O)2-CH3, methyl acetal, and one or more substances having the formula H3C-O-(CH2O). n Z, a mixture of polyoxymethylene dimethyl ether products with -CH3, 3≤n≤20 P , - The product mixture Z P The product mixture Z is introduced into distillation unit D1 and distilled. P Separation into a first fraction and a second fraction, the first fraction containing methyl acetal and serving as the top stream KS D1 Leaving the distillation unit D1, the second fraction contains H3C-O-(CH2O)2-CH3 and one or more compounds having the formula H3C-O-(CH2O). n -CH3, 3≤n≤20 polyoxymethylene dimethyl ether and as the bottom stream SS D1 Leaving the distillation unit D1, -The bottom flow SS D1 The bottom stream SS is introduced into distillation unit D2 and distilled. D1 Separation into a first fraction and a second fraction, the first fraction containing H3C-O-(CH2O)2-CH3 and serving as the top stream KS D2 Leaving the distillation unit D2, the second fraction contains one or more components having the formula H3C-O-(CH2O). n -CH3, 3≤n≤20 polyoxymethylene dimethyl ether and as the bottom stream SS D2 It leaves the distillation unit D2.

2. The method according to claim 1, wherein the reactant composition Z R Contains methyl acetal and one or more of the above having the formula H3C-O-(CH2O). n -CH3, 3≤n≤20 polyoxymethylene dimethyl ether, with a total concentration of at least 90% by mass, more preferably at least 95% by mass.

3. The method according to claim 1 or 2, wherein the reactant composition Z R It is free of formaldehyde, methanol and / or non-aqueous, or contains formaldehyde, methanol and water and its total concentration is less than 5% by mass, preferably less than 0.5% by mass.

4. The method according to any of the preceding claims, wherein in the reactant composition Z R The substance present in it has the formula H3C-O-(CH2O). n -CH3,3≤n≤20 polyoxymethylene dimethyl ether has a mass average molecular weight in the range of 136 g / mol to 210 g / mol.

5. The method according to any of the preceding claims, wherein the reactant composition Z R The methyl acetal and one or more polyoxymethylene dimethyl ethers in the mixture have a mass average molecular weight in the range of 90 g / mol to 190 g / mol.

6. The method according to any of the preceding claims, wherein the topstream KS exiting the distillation unit D1 D1 The bottom stream SS is returned to the reactor R1 and / or exits the distillation unit D2. D2 It is returned to the reactor R1.

7. The method according to any of the preceding claims, wherein the reactant composition Z R The at least part of it contains the formula H3C-O-(CH2O) n -CH3, 3≤n≤20 polyoxymethylene dimethyl ether is produced in a separate production unit and then fed into the reactor R1.

8. The method of claim 7, wherein the topstream KS exiting the distillation unit D1 D1 and / or the bottom stream SS exiting distillation unit D2 D2 It is returned to the individual production unit.

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