Hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol and its preparation method

Abstract

This invention belongs to the field of catalyst preparation technology, specifically relating to a hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol and its preparation method. In this hydrogenation catalyst, the total content of the active components nickel and copper is 12-28%, the auxiliary agent is alkaline earth metal calcium or magnesium, and the support is self-made strip-shaped silicon carbide. This catalyst is used in the hydrogenation refining of ethylene glycol, effectively improving the ultraviolet light transmittance of the ethylene glycol product. The obtained ethylene glycol product achieves excellent transmittance at 220nm, 275nm, and 350nm, meeting polyester grade standards. Furthermore, the catalyst exhibits significantly better stability over long-term operation than catalysts using Al2O3 as a support.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol and its preparation method. Background Technology

[0002] Ethylene glycol (MEG) is an important organic chemical raw material. It is mainly used in the production of polyester resins, antifreeze, unsaturated polyester resins, lubricants, plasticizers, nonionic surfactants, and explosives. It can also be used as a hydraulic fluid and capacitor electrolyte. Since the discovery in the 1950s that ethylene glycol reacts with terephthalic acid (PTA) to produce PETP polyester, its largest application has been in the production of polyester resins (fibers and films). Currently, approximately 94.0% of total ethylene glycol consumption is used in the production of polyester resins.

[0003] When ethylene glycol is used in the production of polyester fibers, its quality significantly impacts downstream products. Ultraviolet transmittance (UV value) sensitively reflects the impurity content in ethylene glycol products, indirectly indicating their quality. Therefore, UV value is internationally widely used to control ethylene glycol quality. Pure ethylene glycol has no absorption in the ultraviolet region, and its UV transmittance is 100%. Impurities in ethylene glycol lead to a decrease in UV value; different impurity contents cause ethylene glycol to absorb at varying degrees in the 200–400 nm ultraviolet region, resulting in different UV values. Low UV values ​​affect the coloring, strength, and color of downstream polyester fibers.

[0004] Impurities affecting the UV value of ethylene glycol are mainly carbonyl or conjugated double bond compounds. Among the methods for producing ethylene glycol, the coal-to-syngas route, a new technological route compared to the ethylene process, is less expensive, costing only about two-thirds of the epoxide process. However, this process generates impurities not present in the original ethylene process. The main impurities include: methyl glycolate, 1,2-butanediol, methyl formate, dimethyl ether, dioxolane, methyl methoxyacetate, ethylene glycol monomethyl ether, 1,2-propanediol, ethylene glycol mono(di)formate, and more than 30 others. These carbonyl-containing impurities have significant absorption in the 220nm-350nm wavelength range of ultraviolet light. If used in the production of downstream products, they will directly affect the quality of downstream ethylene glycol products and therefore must be removed.

[0005] Currently, commonly used production processes for improving the UV value of MEG products mainly fall into two categories: adsorption and selective catalytic hydrogenation. While adsorption can achieve the goal of increasing the UV value of MEG products, it still has significant limitations. Selective catalytic hydrogenation is a MEG purification method that has recently gained widespread attention and application. Its advantage lies in its more selective removal of impurities from MEG materials, achieving better removal efficiency than traditional adsorption methods. Under the action of a catalyst, unsaturated compounds are hydrogenated to generate compounds with lower boiling points, thereby effectively removing carbonyl or conjugated double bond compounds contained in ethylene glycol products, further improving the UV value of MEG products.

[0006] In the refining of ethylene glycol, nickel-aluminum alloys and nickel-based catalysts supported on alumina are commonly used. Chinese patents CN108855089A and CN108855090A provide two types of ethylene glycol hydrogenation refining catalysts. The support is either alumina-titanium oxide composite oxide treated with steam or alumina-magnesium oxide composite oxide treated with acidic steam; the additive is an alkaline earth metal or its oxide; and the active ingredient is nickel or its oxide. Applying this catalyst to the hydrogenation reaction of ethylene glycol enables the ethylene glycol product to reach polyester grade, increasing the product's added value. The catalyst exhibits high stability and is suitable for industrial plants. However, when using alumina as the catalyst support, the high acid content on the alumina surface can cause side reactions such as impurity polymerization and condensation at high temperatures, resulting in low catalytic efficiency and negatively impacting long-term catalyst operation.

[0007] CN107973700A discloses a method for hydrogenating and refining ethylene glycol. This method employs a two-stage hydrogenation process using a Raney nickel catalyst supported on a polymeric material. Poor-quality ethylene glycol feedstock (low UV transmittance) is hydrogenated and upgraded through a multi-stage hydrogenation process to obtain polyester-grade ethylene glycol. CN104945227A discloses a composite hydrogenation catalyst for ethylene glycol hydrogenation and refining. This catalyst comprises a continuous phase of carbon and dispersed phase Raney alloy particles, wherein the dispersed phase Raney alloy particles are uniformly or non-uniformly dispersed in the continuous phase of carbon. This catalyst exhibits good particle strength and high catalytic activity, significantly improving the UV transmittance of ethylene glycol after hydrogenation. However, the supports used are all organic materials, which suffer from dissolution issues in ethylene glycol. The supports continuously leak out, leading to unstable catalyst performance. Furthermore, the leaked organic matter also affects the quality of the ethylene glycol product. Summary of the Invention

[0008] The purpose of this invention is to provide a hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol and its preparation method.

[0009] The hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol is a supported catalyst, comprising: support: carbonized silicon carbide (SiC), active components: nickel and copper, and additives: alkaline earth metals.

[0010] The catalyst of this invention has an active component, nickel and copper, with a total content of 12% to 28% of the total mass of the catalyst and a nickel / copper mass ratio greater than 2; its auxiliary alkaline earth metal content accounts for 0.1% to 2% of the total mass of the catalyst; the remainder is silicon carbide support, with a content of 70% to 86% of the total mass of the catalyst.

[0011] The active components nickel and copper, as well as the alkaline earth metals used in this invention, are all nitrates; the alkaline earth metals are selected from at least one of calcium or magnesium.

[0012] This invention uses SiC as a support, which not only has good thermal conductivity, good chemical stability, and good mechanical strength, but also has no strong acid centers on its surface, thus preventing polymerization or condensation reactions during hydrogenation. At the same time, the catalyst will not cause the support to be lost during use.

[0013] The method for preparing SiC according to the present invention is carried out according to the following steps:

[0014] S1: Take a certain amount of silica and a certain amount of methylcellulose and add them to a ball mill for mixing and grinding for 1-2 hours to obtain a mixture;

[0015] Among them, the silica is fumed silica with a SiO2 content greater than 99%; the amount of methylcellulose used is to ensure that sufficient C content is provided during the preparation of the carrier so that SiO2 can be completely converted into SiC. The amount of silica and methylcellulose used is 1:4~5 in terms of Si / C mass ratio.

[0016] S2: Place the mixture obtained in S1 into an alumina tube furnace and heat it to 1700~1900℃ under the protection of flowing argon gas. The heating rate is 50℃ / h and the argon flow rate is 20mL / min. Maintain the final temperature for 1~2h to ensure complete conversion to SiC, and then cool it to room temperature with the furnace.

[0017] S3: Add a certain amount of methylcellulose to the SiC obtained in S2, mix evenly, and then knead and extrude into strips; wherein, methylcellulose is used as a binder and also plays a role in creating pores, and its amount is 3~4% of the carrier amount by mass percentage.

[0018] S4: The extruded strips are first dried at 120°C, and then the dried strips are calcined in a muffle furnace at 700°C in air for 3 hours to finally obtain light green silicon carbide strip-shaped supports. The SiC supports prepared in this invention are clover-shaped with dimensions of Ø3×5.

[0019] During the carrier preparation process, the purpose of calcining S4 in a muffle furnace is to remove excess C from the preparation process and to remove methylcellulose added as a binder, thereby forming a carrier with a large specific surface area.

[0020] The preparation method of the catalyst of the present invention includes the following steps:

[0021] S1: Prepare a solution by mixing a certain amount of the active components nickel nitrate, copper nitrate, and nitrates of the auxiliary agents with deionized water;

[0022] S2: The solution prepared in S1 is impregnated and loaded onto the SiC support;

[0023] S3: The material from S2 is dried at 120°C, and then the dried material is calcined in a muffle furnace at 350~500°C for 4 hours to finally obtain the catalyst.

[0024] The hydrogenation catalyst of this invention is prepared by an equal-volume impregnation method. The impregnation process has no special requirements and employs conventional methods in the art, which are illustrated in the examples. As long as the prepared catalyst meets the target requirements for the content of active components and promoters, it is acceptable.

[0025] The catalyst of this invention is used in the hydrogenation refining of ethylene glycol. Before introducing the feedstock, the catalyst must undergo reduction activation. The reduction activation conditions are: first, nitrogen gas is introduced at a gas hourly space velocity (GHSV) of 200 h⁻¹. -1 The temperature is increased to 110-130℃ at a rate of 20-30℃ / h and held for 1 hour. Then, hydrogen gas is introduced to adjust the hydrogen concentration to 5%, i.e., the reducing atmosphere composition is 5% H2 + 95% N2. The temperature is increased to 200-220℃ at a rate of 10-20℃ / h and held for 1.5-2 hours, increasing the hydrogen concentration in the reducing gas to 50% H2 + 50% N2. The temperature is increased to 440-460℃ at a rate of 5-10℃ / h and held for 1 hour, successively increasing the hydrogen concentration in the reducing gas to 65% H2 + 35% N2, 80% H2 + 20% N2, and 100% H2. The temperature is held for 1 hour, and the reducing atmosphere is pure H2, thus the reduction and activation are complete.

[0026] The catalyst prepared according to this invention is used in the hydrogenation refining of ethylene glycol. The catalyst product is loaded into a fixed-bed tubular reactor, first undergoing reduction, and then reactants are introduced for hydrogenation. The reaction pressure is controlled at 0.2 MPa–1.0 MPa, the reaction temperature at 50°C–150°C, and the liquid hourly space velocity at 0.5–5.0 h⁻¹. -1 The molar ratio of hydrogen to ethylene glycol is 5–100.

[0027] Using the catalyst of this invention for the hydrogenation refining of ethylene glycol can achieve the following beneficial effects:

[0028] (1) The catalyst of the present invention uses self-made SiC as a support, which eliminates the acidity of the support, avoids polymerization or condensation reactions caused during the reaction process, and avoids the loss of the support during the use of the catalyst.

[0029] (2) The catalyst of the present invention is used for hydrogenation refining of ethylene glycol, which effectively reduces the content of impurity carbonyl or conjugated double bond compounds that affect the UV value of ethylene glycol, and ultimately effectively improves the UV transmittance of ethylene glycol products, ensuring that the rate of superior ethylene glycol products is 100%, that is, the UV transmittance at 220 nm wavelength is greater than 75%, the UV transmittance at 275 nm wavelength is greater than 92%, and the UV transmittance at 350 nm wavelength is greater than 99%. Attached Figure Description

[0030] Figure 1 The infrared spectrum of β-SiC prepared in Example 1;

[0031] Figure 2 XRD patterns of β-SiC support (a is the support containing unconverted SiO2, b is the support without SiO2). Detailed Implementation

[0032] This invention is implemented according to the above-described manner, and will be described in detail below through embodiments. The purpose of listing these embodiments is merely to explain the invention, not to limit it. Any modifications or alterations that can be easily implemented by those skilled in the art without departing from the technical solutions of this invention will fall within the scope of the claims. The endpoints and any values ​​of the ranges disclosed in the embodiments of this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of various ranges, the endpoint values ​​of 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.

[0033] Unless otherwise specified in the following examples and comparative examples, the experimental procedures or conditions can be followed according to conventional experimental procedures and conditions in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0034] In the examples and comparative examples:

[0035] Fumed silica was purchased from Weifang Sanjia Chemical Co., Ltd.

[0036] The nickel salt used is nickel nitrate hexahydrate, the copper salt is copper nitrate trihydrate, the calcium salt is calcium nitrate tetrahydrate, and the magnesium salt is magnesium nitrate hexahydrate.

[0037] The C content in methylcellulose is 44% by mass.

[0038] The catalysts are all clover-shaped.

[0039] The content of each component in the hydrogenation feedstock and hydrogenation products was analyzed by gas chromatography, and the UV values ​​were detected by ultraviolet absorption detector.

[0040] Example 1: Carrier preparation:

[0041] S1: Weigh 120g of fumed silica and 218g of methylcellulose (Si / C ratio 1:4), add them together to a ball mill and mix and grind for 1 hour to obtain a uniformly mixed mixture;

[0042] S2: Place the mixture of S1 into an alumina tube furnace and heat it to 1800℃ under the protection of flowing argon gas at a heating rate of 50℃ / h and an argon flow rate of 20mL / min. Hold it at the final temperature for 2h to ensure complete conversion to SiC, and then cool it to room temperature with the furnace.

[0043] S3: Add 3g of methylcellulose to 100g of SiC obtained in S2, mix evenly, and then knead and extrude to form a clover-shaped strip with dimensions of Ø3×5.

[0044] S4: The strips extruded from S3 are first dried at 120℃, and then calcined in air at 700℃ for 3 hours in a muffle furnace to obtain a light green silicon carbide strip-shaped support. Infrared spectroscopy identifies it as β-SiC, and the BET specific surface area of ​​this support is 152 μm. 2 / g.

[0045] Example 2: Carrier preparation:

[0046] S1: Weigh 120g of fumed silica and 272g of methylcellulose (Si / C ratio 1:5), add them together to a ball mill and mix and grind for 2 hours to obtain a uniformly mixed mixture;

[0047] S2: Place the mixture of S1 into an alumina tube furnace and heat it to 1700℃ under the protection of flowing argon gas at a heating rate of 50℃ / h and an argon flow rate of 20mL / min. Hold it at the final temperature for 2h to ensure complete conversion to SiC, and then cool it to room temperature with the furnace.

[0048] S3: Add 4g of methylcellulose to 100g of SiC obtained in S2, mix evenly, and then knead and extrude to form a clover-shaped strip with dimensions of Ø3×5.

[0049] S4: The strips extruded from S3 are first dried at 120℃, and then calcined in air at 700℃ for 3 hours in a muffle furnace to obtain a light green silicon carbide strip-shaped support. Infrared spectroscopy identifies it as β-SiC, and the BET specific surface area of ​​this support is 147 μm. 2 / g.

[0050] Example 3: Carrier preparation:

[0051] S1: Weigh 120g of fumed silica and 245g of methylcellulose (Si / C ratio 1:4.5), add them together to a ball mill and mix and grind for 2 hours to obtain a uniformly mixed mixture;

[0052] S2: Place the mixture of S1 into an alumina tube furnace and heat it to 1900℃ under the protection of flowing argon gas at a heating rate of 50℃ / h and an argon flow rate of 20mL / min. Hold it at the final temperature for 1h to ensure complete conversion to SiC, and then cool it to room temperature with the furnace.

[0053] S3: Add 3.5g of methylcellulose to 100g of SiC obtained in S2, mix evenly, and then knead and extrude to form a clover-shaped strip with dimensions of Ø3×5.

[0054] S4: The strips extruded from S3 are first dried at 120℃, and then calcined in air at 700℃ for 3 hours in a muffle furnace to obtain a light green silicon carbide strip-shaped support. Infrared spectroscopy identifies it as β-SiC, and the BET specific surface area of ​​this support is 135 μm. 2 / g.

[0055] Example 4: Carrier preparation:

[0056] S1: Weigh 120g of fumed silica and 245g of methylcellulose (Si / C ratio 1:4.5), add them together to a ball mill and mix and grind for 2 hours to obtain a uniformly mixed mixture;

[0057] S2: Place the mixture of S1 into an alumina tube furnace and heat it to 1600℃ under the protection of flowing argon gas at a heating rate of 50℃ / h and an argon flow rate of 20mL / min. Hold it at the final temperature for 1h to ensure complete conversion to SiC, and then cool it to room temperature with the furnace.

[0058] S3: Add 3.5g of methylcellulose to 100g of SiC obtained in S2, mix evenly, and then knead and extrude to form a clover-shaped strip with dimensions of Ø3×5.

[0059] S4: The strips extruded from S3 are first dried at 120℃, and then calcined in air at 700℃ for 3 hours in a muffle furnace to obtain a light green silicon carbide strip-shaped support. Infrared spectroscopy identifies it as β-SiC, and the BET specific surface area of ​​this support is 97 μm. 2 / g.

[0060] Example 5: Carrier preparation:

[0061] S1: Weigh 120g of fumed silica and 164g of methylcellulose (Si / C ratio 1:3), add them together to a ball mill and mix and grind for 2 hours to obtain a uniformly mixed mixture;

[0062] S2: Place the mixture of S1 into an alumina tube furnace and heat it to 1800℃ under the protection of flowing argon gas at a heating rate of 50℃ / h and an argon flow rate of 20mL / min. Hold it at the final temperature for 1h to ensure complete conversion to SiC, and then cool it to room temperature with the furnace.

[0063] S3: Add 3.5g of methylcellulose to 100g of SiC obtained in S2, mix evenly, and then knead and extrude to form a clover-shaped strip with dimensions of Ø3×5.

[0064] S4: The strips extruded from S3 are first dried at 120℃, and then calcined in air at 700℃ for 3 hours in a muffle furnace to obtain a light green silicon carbide strip support. XRD analysis shows that it contains β-SiC and unconverted SiO2. The BET specific surface area of ​​this support is 103 μm. 2 / g.

[0065] Example 6: Carrier preparation:

[0066] S1: Weigh 120g of fumed silica and 327g of methylcellulose (Si / C ratio 1:6), add them together to a ball mill and mix and grind for 2 hours to obtain a uniformly mixed mixture;

[0067] S2: Place the mixture of S1 into an alumina tube furnace and heat it to 1800℃ under the protection of flowing argon gas at a heating rate of 50℃ / h and an argon flow rate of 20mL / min. Hold it at the final temperature for 1h to ensure complete conversion to SiC, and then cool it to room temperature with the furnace.

[0068] S3: Add 3.5g of methylcellulose to 100g of SiC obtained in S2, mix evenly, and then knead and extrude to form a clover-shaped strip with dimensions of Ø3×5.

[0069] S4: The strips extruded from S3 are first dried at 120℃, and then calcined in air at 700℃ for 3 hours in a muffle furnace to obtain a light green silicon carbide strip support. XRD analysis shows that it contains β-SiC and does not contain unconverted SiO2. The BET specific surface area of ​​this support is 83 μm. 2 / g.

[0070] Example 7

[0071] Catalyst preparation: The support was prepared using the method in Example 1. 100g of nickel nitrate hexahydrate, 8g of copper nitrate trihydrate, and 0.6g of calcium nitrate tetrahydrate were added to 80ml of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 500°C for 4 hours to obtain catalyst A1. By mass percentage, this catalyst contains 26% nickel, 2% copper, and 0.1% calcium, with the remainder being a SiC support.

[0072] Example 8

[0073] Catalyst preparation: The support was prepared using the method in Example 1. 47g of nickel nitrate hexahydrate, 23g of copper nitrate trihydrate, and 8.7g of magnesium nitrate hexahydrate were added to 80mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst A2. By mass percentage, this catalyst contains 12% nickel, 6% copper, and 2% magnesium, with the remainder being a SiC support.

[0074] Example 9

[0075] Catalyst preparation: The support was prepared using the method in Example 1. 78g of nickel nitrate hexahydrate, 15g of copper nitrate trihydrate, and 12g of calcium nitrate tetrahydrate were added to 80mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 350°C for 4 hours to obtain catalyst A3. By mass percentage, this catalyst contains 20% nickel, 4% copper, 2% calcium, and the remainder is a SiC support.

[0076] Example 10

[0077] Catalyst preparation: The support was prepared using the method in Example 1. 70g of nickel nitrate hexahydrate, 15g of copper nitrate trihydrate, and 0.45g of magnesium nitrate hexahydrate were added to 80mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 400°C for 4 hours to obtain catalyst A4. By mass percentage, this catalyst contains 18% nickel, 4% copper, and 0.1% magnesium, with the remainder being a SiC support.

[0078] Example 11

[0079] Catalyst preparation: The support was prepared using the method in Example 1. 39g of nickel nitrate hexahydrate, 11g of copper nitrate trihydrate, and 6g of calcium nitrate tetrahydrate were added to 100mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst A5. By mass percentage, this catalyst contains 10% nickel, 3% copper, and 1% calcium, with the remainder being a SiC support.

[0080] Example 12

[0081] Catalyst preparation: The support was prepared using the method in Example 1. 62g of nickel nitrate hexahydrate, 11g of copper nitrate trihydrate, and 4.5g of magnesium nitrate hexahydrate were added to 80mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst A6. By mass percentage, this catalyst contains 16% nickel, 3% copper, and 1% magnesium, with the remainder being a SiC support.

[0082] Example 13

[0083] Catalyst preparation: The support was prepared using the method in Example 1. 93g of nickel nitrate hexahydrate, 11g of copper nitrate trihydrate, 6g of calcium nitrate tetrahydrate, and 4.5g of magnesium nitrate hexahydrate were added to 100mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst A7. By mass percentage, this catalyst contains 24% nickel, 3% copper, 1% calcium, and 1% magnesium, with the remainder being a SiC support.

[0084] Example 14

[0085] Catalyst preparation: The support was prepared using the method in Example 1. 93g of nickel nitrate hexahydrate, 23g of copper nitrate trihydrate, 6g of calcium nitrate tetrahydrate, and 4.5g of magnesium nitrate hexahydrate were added to 100mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst A8. By mass percentage, this catalyst contains 24% nickel, 6% copper, 1% calcium, and 1% magnesium, with the remainder being a SiC support.

[0086] Comparative Example 1

[0087] Catalyst preparation: The support was prepared using the method in Example 1. 70g of nickel nitrate hexahydrate and 15g of copper nitrate trihydrate were added to 80mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst B1. By mass percentage, this catalyst contains 18% nickel, 4% copper, and the remainder is a SiC support.

[0088] Comparative Example 2

[0089] Catalyst preparation: The support was prepared using the method in Example 1. 78g of nickel nitrate hexahydrate, 20g of cobalt nitrate hexahydrate, and 8.7g of magnesium nitrate hexahydrate were added to 80mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst B2. By mass percentage, this catalyst contains 20% nickel, 4% cobalt, and 2% magnesium, with the remainder being a SiC support.

[0090] Comparative Example 3

[0091] Catalyst preparation: The support preparation was the same as in Example 1. 78g of nickel nitrate hexahydrate and 12g of calcium nitrate tetrahydrate were added to 80mL of deionized water to prepare a solution. This solution was then loaded onto 100g of the silicon carbide strip support prepared in Example 1 using a conventional impregnation method. The material was then dried at 120°C and subsequently calcined in a muffle furnace at 450°C for 4 hours to obtain catalyst B3. By mass percentage, this catalyst contains 20% nickel, 2% calcium, and the remainder is a SiC support.

[0092] Comparative Example 4

[0093] The carrier was commercially available clover strip Al2O3, with a specification of Ø3×5.

[0094] Catalyst preparation: 100g of nickel nitrate hexahydrate, 8g of copper nitrate trihydrate, and 0.6g of calcium nitrate tetrahydrate were added to 100mL of deionized water to prepare a solution. This solution was then loaded onto 100g of clover-shaped Al2O3 support using a conventional impregnation method. The material was then dried at 120℃ and subsequently calcined in a muffle furnace at 500℃ for 4 hours to obtain catalyst B4. By mass percentage, this catalyst contains 26% nickel, 2% copper, and 0.1% calcium, with the remainder being the Al2O3 support.

[0095] Performance testing:

[0096] The catalysts prepared in Examples 7-14 and Comparative Examples 1-4 were used for the hydrogenation of ethylene glycol. The catalysts were loaded into a fixed-bed reactor and first activated by reducing nitrogen gas containing hydrogen. The reduction and activation conditions were as follows: nitrogen gas was first introduced, and the gas hourly space velocity was 200 h⁻¹. -1 The temperature was increased to 130℃ at a rate of 20℃ / h and held for 1 hour. Then, hydrogen gas was introduced to adjust the hydrogen concentration to 5%, resulting in a reducing atmosphere of 5% H₂ + 95% N₂. The temperature was then increased to 200℃ at a rate of 10℃ / h and held for 2 hours, increasing the hydrogen concentration in the reducing gas to 50% H₂ + 50% N₂. The temperature was then increased to 460℃ at a rate of 5℃ / h and held for 1 hour, successively increasing the hydrogen concentration in the reducing gas to 65% H₂ + 35% N₂, 80% H₂ + 20% N₂, and finally 100% H₂. This temperature was maintained for 1 hour, resulting in a pure H₂ reducing atmosphere, marking the end of the reduction activation. After reduction, the reaction temperature was adjusted to 120℃, and the system pressure to 0.5 MPa. Ethylene glycol, after preheating, was introduced into the reaction tube, and the liquid hourly space velocity (LISH) of the ethylene glycol was controlled at 3.5 h⁻¹. -1 The hydrogen-to-oil molar ratio was controlled at 50:1. Ethylene glycol, obtained by ester hydrogenation via syngas method, was used as the raw material. The UV values ​​of the raw material at 220 nm, 275 nm, and 350 nm were 14.3%, 64.2%, and 92.6%, respectively. The UV values ​​of the hydrogenated product were measured using a UV absorption detector, and the results after 48 hours and 200 hours are shown in Tables 1 and 2, respectively.

[0097] Table 1. Ultraviolet transmittance of products after 48 hours of hydrorefining with different catalysts

[0098]

[0099] Table 2. UV transmittance of products after 200 hours of hydrogenation purification with different catalysts

[0100]

[0101] As can be seen from Tables 1 and 2, when the catalyst provided by this invention is used for the hydrogenation refining of ethylene glycol, the ethylene glycol products obtained have ultraviolet light transmittance at 220 nm, 275 nm and 350 nm that all reach the excellent grade of ethylene glycol products and meet the polyester grade standard. Moreover, the long-term operation stability of the catalyst is significantly better than that of the catalyst using Al2O3 as a support.

Claims

1. A hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol, characterized in that, The hydrogenation catalyst is composed of dual active components nickel and copper, an alkaline earth metal auxiliary agent, and a support. The total mass content of the active components nickel and copper is 12-28%, the mass content of the auxiliary agent is 0.1-2%, and the remainder is the support.

2. The hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 1, characterized in that, The active components nickel and copper, as well as the alkaline earth metals used as additives, are all nitrates; the mass ratio of nickel to copper in the active components is greater than 2, and the alkaline earth metals used as additives are one or both of calcium and magnesium.

3. The hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 1, characterized in that, The catalyst support is SiC that has undergone carbonization treatment. The preparation steps of SiC are as follows: S1: Add silica and methylcellulose to a ball mill and mix and grind them to obtain a mixture; S2: The mixture obtained in S1 is placed in an alumina tube furnace for reaction. The temperature is increased under the protection of flowing argon gas to ensure complete conversion to SiC, and then cooled to room temperature with the furnace. S3: Add methylcellulose to the SiC obtained in S2, mix evenly, and then knead and extrude to form strips; S4: The strips extruded from S3 are first dried at 120°C, and then the dried strips are calcined in air at 700°C for 3 hours in a muffle furnace to obtain light green clover-shaped Ø3×5 silicon carbide strip carriers.

4. The hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 3, characterized in that, In S1, the silica is fumed silica produced by the gas phase method, and its SiO2 content is greater than 99%.

5. The hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 3, characterized in that, In S1, the amount of methylcellulose used is to ensure sufficient C content during the carrier preparation process so that SiO2 can be completely converted into SiC. The amount of silica and methylcellulose used is 1:4~5 in terms of Si / C mass ratio.

6. The hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 3, characterized in that, In S2, the reaction temperature in the high-temperature furnace is 1700~1900℃, the heating rate is 50℃ / h, the argon flow rate is 20mL / min, and the final temperature is maintained for 1~2h.

7. The hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 3, characterized in that, In S3, the amount of methylcellulose used, by mass percentage, is 3 to 4% of the carrier mass.

8. A method for preparing a hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 1, characterized in that, The catalyst was prepared using a conventional impregnation method, with the specific steps as follows: S1: Prepare a solution by mixing the active components nickel nitrate, copper nitrate, and nitrates of the auxiliary agents with deionized water; S2: The solution prepared in S1 is impregnated and loaded onto the SiC support; S3: The material from S2 is dried at 120°C, and then the dried material is calcined in a muffle furnace at 350~500°C for 4 hours to finally obtain the catalyst.

9. The application of a hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 1, characterized in that, The catalyst is used for the hydrogenation refining of ethylene glycol, and it must be reduced and activated before use.

10. The application of the hydrogenation catalyst for improving the ultraviolet light transmittance of ethylene glycol as described in claim 9, characterized in that, The conditions for hydrogenation purification of ethylene glycol are as follows: the catalyst is loaded into a fixed-bed reactor, the reaction pressure is controlled at 0.2 MPa to 1.0 MPa, the reaction temperature is 50℃ to 150℃, and the liquid hourly space velocity is 0.5 to 5.0 h⁻¹. -1 The molar ratio of hydrogen to ethylene glycol is 5–100.

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