Method for catalytically degrading glycolate oligomer
By using titanium, tin, and molybdenum oxide catalysts to catalytically degrade glycolate oligomers, the problem of difficult recycling of glycolate oligomers has been solved, achieving efficient conversion into valuable substances and reducing production costs and operational difficulties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-12
- Publication Date
- 2026-05-12
AI Technical Summary
The lack of effective methods in the current technology to decompose the glycolate oligomers generated in the PGA production process into recyclable valuable substances leads to resource waste and increased production costs.
Using titanium, tin, and molybdenum oxide catalysts, glycolate oligomers are reacted in the presence of low-carbon alcohols. Through a mild catalytic degradation process, the glycolate oligomers are converted into valuable substances such as methyl glycolate and ethylene glycol.
It achieves efficient degradation of glycolate oligomers, reduces byproduct generation, lowers operational difficulty and cost, and improves the recycling value of resources.
Smart Images
Figure BDA0005132019130000071 
Figure BDA0005132019130000081
Abstract
Description
Technical Field
[0001] This invention relates to the field of chemical waste treatment, and specifically to a method for catalytic degradation of glycolate oligomers. Background Technology
[0002] Polyglycolic acid (PGA), also known as polyhydroxyacetic acid, is a highly crystalline, biodegradable aliphatic polymer mainly used in medical consumables and agricultural films. In regions with abundant coal resources, it is primarily produced from coal-derived syngas. First, dimethyl oxalate (DMO) is prepared from the coal-derived syngas, and then methyl glycolate prepared by hydrogenating DMO is polymerized to generate PGA. This synthesis method generates a large amount of fusel oil, a byproduct containing polymers, during production. Failure to recover this byproduct would result in significant waste and increase production costs.
[0003] Currently, the recovery of polymers from fusel oils is mainly divided into physical recovery and chemical recovery. Because polymers have good biodegradability, chemical recovery is easier to implement than physical recovery. Chemical recovery involves depolymerizing the polymer into monomers through processes such as alcoholysis, pyrolysis, hydrolysis, and ammonolysis, which are then recycled. However, for polymers generated during PGA production, there is currently no suitable method available to decompose them into other recyclable monomers.
[0004] Therefore, there is an urgent need to develop a method to decompose polymers in fusel oil, a byproduct of the PGA process, into recyclable and valuable substances. Summary of the Invention
[0005] The purpose of this invention is to overcome the problem that existing technologies cannot effectively degrade and recover glycol ester oligomers from fusel oils, and to provide a method for catalytic degradation of glycol ester oligomers.
[0006] To achieve the above objectives, the present invention provides a method for degrading glycolate oligomers, the method comprising: reacting a raw material containing glycolate oligomers with a low alcohol in the presence of a catalyst, wherein the contents of titanium oxide, tin oxide and molybdenum oxide in the catalyst are 20-90 wt%, 2-55 wt% and 0.3-40 wt%, respectively.
[0007] The beneficial effects of the present invention through the above technical solution include at least the following:
[0008] The degradation method provided by this invention has simple process steps and mild conditions. Without increasing the amount of low-carbon alcohols, the catalyst provided by this invention can fully promote the degradation of glycolate oligomers. While degrading glycolate oligomers, it can also reduce the generation of by-products, so that more glycolate oligomers are converted into substances with recycling value, thereby reducing costs. In addition, the method provided by this invention further simplifies the production process, can continuously and efficiently degrade glycolate oligomers, and reduce the difficulty and cost of operation. Detailed Implementation
[0009] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0010] The present invention provides a method for degrading glycolate oligomers, the method comprising: reacting a raw material containing glycolate oligomers with a lower alcohol in the presence of a catalyst.
[0011] In this invention, the contents of titanium oxide, tin oxide and molybdenum oxide in the catalyst are preferably 20-90 wt%, 2-55 wt% and 0.3-40 wt%, respectively.
[0012] In this invention, the raw material containing glycolate oligomers can be derived from fusel oil containing glycolate oligomers produced during the industrial hydrogenation of dimethyl oxalate, preferably including at least one of ethylene glycol, glycolic acid, and methyl glycolate, as well as oligomers generated by polymerization of at least one of ethylene glycol, glycolic acid, and methyl glycolate. Oligomers refer to homopolymers or copolymers obtained by polymerizing ethylene glycol, glycolic acid, methyl glycolate, etc.
[0013] In this invention, the weight-average molecular weight of the oligomer can be 200-5000 g / mol (measured by high performance permeation gel chromatography (GPC)).
[0014] In this invention, the content of the oligomer in the raw material containing glycolate oligomer can be 5 wt% or more, preferably 10-80 wt%.
[0015] In this invention, the content of ethylene glycol in the raw material containing glycolate oligomer can be 15-80 wt%, the content of methyl glycolate can be 0-30 wt%, and the content of glycolic acid can be 0-10 wt%.
[0016] According to the present invention, when the raw material containing glycolate polymer is fusel oil containing glycolate oligomers produced by hydrogenation of dimethyl oxalate, it usually also contains heavy impurities, the content of which is generally 5-15 wt%.
[0017] In this invention, the weight ratio of the glycolate-containing oligomer to the lower alcohol can be 1:(0.3-20), and can be 1:0.3, 1:0.5, 1:1, 1:3, 1:5, 1:7, 1:8, 1:10, 1:11, 1:13, 1:15, 1:17, 1:19, 1:20, or any two of the above values within a range, preferably 1:(0.5-2.5). The weight of the glycolate-containing oligomer is based on the weight of the glycolate oligomer. It is understood that within a certain range, when the amount of glycolate oligomer is constant, the higher the amount of lower alcohol used as the raw material for decomposing the glycolate oligomer, the higher the conversion rate of the glycolate oligomer. Therefore, technical solutions involving higher amounts of lower alcohol are all within the scope of this invention. However, the catalyst prepared by the present invention can minimize the amount of low alcohols while improving conversion rate and selectivity. Therefore, even if the amount of low alcohols used in the present invention is within the above-mentioned low range, it can still achieve efficient conversion of glycolate oligomers.
[0018] In this invention, the lower alcohol is a substance that can decompose glycolate oligomers, such as methanol and ethanol. For example, it can be at least one of C1-C4 alcohols, preferably methanol.
[0019] In this invention, there is no particular limitation on the amount of catalyst used, as long as it is sufficient to fully decompose the glycolate oligomers. Preferably, the liquid hourly space velocity (LHSV) of the glycolate oligomer-containing feedstock is 0.01-1 h⁻¹. -1 The weight of the raw material containing glycolate oligomers is based on the weight of the glycolate oligomers.
[0020] In this invention, the content of titanium oxide in the catalyst is preferably 25-85 wt%, for example, it can be any value within a range of 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, or any value above, and more preferably 55-65 wt%.
[0021] In this invention, the content of the tin oxide catalyst is preferably 3-50 wt%, for example, it can be any value within a range of 3 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, or more, and more preferably 15-25 wt%.
[0022] In this invention, the content of the molybdenum oxide catalyst is preferably 0.5-35 wt%, for example, it can be any value within a range of 0.5 wt%, 3 wt%, 7 wt%, 11 wt%, 15 wt%, 19 wt%, 23 wt%, 27 wt%, 31 wt%, 35 wt%, or more, and more preferably 15-25 wt%.
[0023] By employing the above-mentioned preferred catalyst, the conversion rate of glycolic acid oligomers and the selectivity of the products methyl glycolate and ethylene glycol can be further improved.
[0024] In this invention, there are no special requirements for the preparation of the catalyst, as long as the contents of titanium oxide, tin oxide and molybdenum oxide meet the aforementioned range. It can be obtained by directly mixing the individual oxides, or by calcining a mixture of titanium precursor, tin precursor and molybdenum precursor. According to a preferred embodiment of this invention, the preparation of the catalyst includes grinding, drying and shaping a mixture containing titanium oxide, tin oxide and molybdenum oxide.
[0025] According to the present invention, the grinding can be carried out in any grinding equipment, such as a ball mill, as long as the fineness of the ground particles is uniform and can be prepared into a catalyst. Preferably, the average particle size of the ground powder is 5-800 μm, and more preferably 10-150 μm.
[0026] In this invention, the reaction conditions include: a temperature of 80-250°C, for example, any value within or above of 80°C, 100°C, 120°C, 140°C, 160°C, 180°C, 200°C, 220°C, 240°C, 250°C; a pressure of 0.1-4 MPa, for example, any value within or above of 0.1 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa; and a time of 20-120 min.
[0027] The inventors of this invention have discovered that when using the catalyst provided by this invention to degrade glycolate oligomers, the glycolate oligomers can be fully degraded. Although other byproducts may be generated besides methyl glycolate and ethylene glycol, these byproducts do not adhere to the reaction vessel and affect the reaction efficiency. That is, the catalytic process does not require manual feeding or removal of materials, nor does it require periodic cleaning of the reaction vessel. Therefore, the reaction is preferably carried out in a continuously fed device, which includes a continuously fed fixed bed or a continuously stirred tank reactor, preferably a continuously fed fixed bed. Furthermore, the method of material entry and exit in the device is not limited, as long as continuous entry and exit can be achieved; for example, it can be any of the following methods: top-in / bottom-out, bottom-in / top-out, or lateral entry and exit. According to a preferred embodiment of this invention, in order to reduce the energy required for transportation and equipment costs, the feeding method is preferably top-in / bottom-out.
[0028] According to the most preferred embodiment of the present invention, the degradation method of the present invention includes:
[0029] First, prepare the catalyst: weigh 58-62 parts by mass of titanium oxide, 15-25 parts by mass of tin oxide and 15-25 parts by mass of molybdenum oxide, mix them, grind them, dry them and shape them to obtain the catalyst;
[0030] Then, in the presence of a catalyst, the glycolate oligomers are degraded: fusel oil and methanol are mixed uniformly, wherein the weight ratio of fusel oil to methanol is 1:(1.8-2.2), and then the reaction is carried out in a continuous-feed fixed-bed reactor at a reaction pressure of 1.8-2.2 MPa, a reaction temperature of 148-152℃, and a reaction time of 35-45 min; the liquid hourly space velocity of the fusel oil is 0.2-0.4 h⁻¹ by weight. -1 .
[0031] The present invention will be described in detail below through examples. Unless otherwise specified, all reagents and materials used in the following examples are commercially available.
[0032] The composition of the liquid was determined by gas chromatography using the normalization method, and the type and content of each component were determined by the chromatographic peaks. While the specific molecular structures of heavy impurities and oligomers were difficult to determine, their retention times in the chromatograms were fixed, and the content of oligomers changed significantly after the reaction, while the content of other impurities remained unchanged before and after the reaction. Therefore, the type and content of each component could be determined.
[0033] Conversion rate of oligomers = (weight of oligomers in fusel oil - weight of oligomers in product) / weight of oligomers in fusel oil × 100%;
[0034] Selectivity of glycolate = (weight of glycolate in product - weight of glycolate in fusel oil) / (weight of oligomer in fusel oil - weight of oligomer in product) × 100%;
[0035] The selectivity of ethylene glycol = (weight of ethylene glycol in the product - weight of ethylene glycol in the fusel oil) / (weight of oligomers in the fusel oil - weight of oligomers in the product) × 100%.
[0036] The composition of the fusel oil is: methyl glycolate 5 wt%, ethylene glycol 52 wt%, glycolate oligomer 33 wt%, and heavy impurities 10 wt%.
[0037] The molding process resulted in an average particle size of 3 mm for the spherical catalyst particles.
[0038] Example 1
[0039] Catalyst preparation:
[0040] Weigh 60 parts by mass of titanium oxide (TiO2), 20 parts by mass of tin oxide (SnO2) and 20 parts by mass of molybdenum oxide (MoO3), mix them and grind them in a ball mill for 1 hour to obtain a mixture with an average particle size of 80 μm; dry the ground mixture in a drying oven at 120°C for 8 hours and shape it to obtain a round granular catalyst.
[0041] Degradation of glycolate oligomers:
[0042] Fusel oil and methanol are mixed evenly at a weight ratio of 1:2 and set aside. A continuous feed fixed-bed reactor is used to pack the prepared catalyst into the fixed bed, which is fixed at both ends with inert packing (quartz sand). The feed method is top-in and bottom-out.
[0043] The reaction pressure was 2 MPa, the reaction temperature was 150 °C, and the liquid hourly space velocity (LHSV) of the fusel oil and methanol was 1 h⁻¹. -1 The reaction time was 40 min. After the reaction was completed, the reaction liquid was taken out under pressure in a gas-liquid separator. The contents of oligomers, methanol, methyl glycol and ethylene glycol in the liquid after the reaction were analyzed by chromatography. The conversion rate of oligomers, the selectivity of methyl glycol and the selectivity of ethylene glycol were calculated. The results are shown in Table 2.
[0044] Examples 2-5
[0045] The catalyst and the degradation of glycolate oligomers were prepared according to Example 1, wherein the total amount of fusel oil used at the end of the reaction was the same relative to each g of catalyst. The difference was that at least one of the following was different: catalyst composition, weight ratio of fusel oil and methanol, reaction pressure, reaction temperature and liquid hourly space velocity, as shown in Table 1. The contents of oligomers, methanol, methyl glycolate and ethylene glycol in the liquid after the reaction were analyzed by chromatography, and the conversion rate of oligomers, the selectivity of methyl glycolate and the selectivity of ethylene glycol were calculated. The results are shown in Table 2.
[0046] Table 1
[0047]
[0048] Comparative Examples 1-7
[0049] Glycolate oligomers were degraded according to the method in Example 1, except that no catalyst was added during the degradation of glycolate oligomers, and the solutions contained no TiO2, SnO2, and MoO3, respectively, and only TiO2, SnO2, and MoO3, respectively. The contents of oligomers, methanol, methyl glycolate, and ethylene glycol in the liquid after the reaction were analyzed by chromatography, and the conversion rate of oligomers, the selectivity of methyl glycolate, and the selectivity of ethylene glycol were calculated. The results are shown in Table 2.
[0050] Table 2
[0051]
[0052] The results from the above examples and comparative examples show that, compared to the comparative examples, Examples 1-5, using the catalyst and method of the present invention to recover methyl glycolate and ethylene glycol from glycolate-containing oligomer fusel oil, can effectively convert high-boiling substances such as glycolate oligomers, thereby recovering methyl glycolate and ethylene glycol. By optimizing the catalyst composition, the weight ratio of fusel oil and lower alcohols, and the reaction conditions, the conversion rate, the selectivity for methyl glycolate, and the selectivity for ethylene glycol are all significantly improved, indicating that in the presence of the catalyst prepared in this invention, efficient conversion of oligomers can be achieved under relatively mild conditions.
[0053] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for catalytically degrading glycolate oligomers, characterized in that, The method includes reacting a raw material containing glycolate oligomers with a lower alcohol in the presence of a catalyst; The contents of titanium oxide, tin oxide, and molybdenum oxide in the catalyst are 20-90 wt%, 2-55 wt%, and 0.3-40 wt%, respectively.
2. The method according to claim 1, wherein, The raw material containing glycolate oligomers is fusel oil containing glycolate oligomers, preferably including at least one of ethylene glycol, glycolic acid and methyl glycolate, and oligomers generated by polymerization of at least one of ethylene glycol, glycolic acid and methyl glycolate. Preferably, the weight-average molecular weight of the oligomer is 200-5000 g / mol.
3. The method according to claim 1 or 2, wherein, The content of the oligomer in the raw material containing glycolate oligomer is 5 wt% or more, preferably 10-80 wt%.
4. The method according to any one of claims 1-3, wherein, The raw material containing glycolate oligomers contains 15-80 wt% ethylene glycol, 0-30 wt% methyl glycolate, and 0-10 wt% glycolic acid.
5. The method according to any one of claims 1-4, wherein, The weight ratio of the raw material containing glycolate oligomer to the low alcohol is 1:(0.3-20), and the weight of the raw material containing glycolate oligomer is based on the weight of the glycolate oligomer.
6. The method according to any one of claims 1-5, wherein, The lower alcohol is at least one of C1-C4 alcohols, preferably methanol.
7. The method according to any one of claims 1-6, wherein, The liquid hourly space velocity (LHSV) of the raw material containing glycolate oligomers is 0.01-1 h⁻¹. -1 The weight of the raw material containing glycolate oligomers is based on the weight of the glycolate oligomers.
8. The method according to any one of claims 1-7, wherein, The contents of titanium oxide, tin oxide and molybdenum oxide in the catalyst are 25-85 wt%, 3-50 wt% and 0.5-35 wt%, respectively, and preferably 55-65 wt%, 15-25 wt% and 15-25 wt%, respectively.
9. The method according to any one of claims 1-8, wherein, The preparation of the catalyst includes grinding, drying, and shaping a mixture containing oxides of titanium, tin, and molybdenum.
10. The method according to any one of claims 1-9, wherein, The reaction conditions include: temperature of 80-250℃, pressure of 0.1-4MPa, and time of 20-120min; And / or, the reaction is carried out in a continuously fed apparatus, wherein the apparatus comprises a continuously fed fixed bed or a continuously stirred tank reactor, preferably a continuously fed fixed bed.