Conversion method for preparing ethylene glycol from ethylene

Abstract

The invention belongs to the technical field of chemical engineering, and discloses a conversion method for preparing ethylene glycol from ethylene. Modified elements are doped into a molecular sieve framework by using an organic template agent, and the oxidation-reduction performance, the acid catalysis performance and the conversion activity of the molecular sieve and the catalyst and the reaction selectivity of a target product are regulated and controlled through the synergistic effect of trace acidic auxiliaries in process operation; the diffusion performance of reactants, intermediates and products in the active component and the catalyst is improved; the technological process has relatively high catalytic conversion performance on the raw material ethylene and high utilization rate of hydrogen peroxide; on the premise of achieving a high conversion target, side reactions are reduced and inhibited in the reaction process, and the selectivity of ethylene glycol is improved; the process steps are saved, the fixed bed operation mode is combined, continuous production and operation of the separation link are facilitated, the ethylene conversion efficiency is high, the product selectivity is good, the hydrogen peroxide utilization rate is high, the production steps are reduced, and the industrial implementation prospect is better by combining the fixed bed mode.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a conversion method for preparing ethylene glycol from ethylene. Background Technology

[0002] Ethylene glycol, also known as glycol or ethylene glycol, is an important derivative of ethylene. It is mainly used in the production of polyesters, as well as in the production of antifreeze, lubricants, plasticizers, surfactants, explosives, paints, adhesives, and inks. It is a crucial basic raw material in the petrochemical industry with a wide range of applications and rapidly increasing consumption. As a vital link in the chemical fiber industry chain, ethylene glycol consumption accounts for the vast majority of domestic consumption in polyester products such as polyester fiber, polyester plastics, and polyester films. With the rapid development of the polyester and chemical fiber product market, China's ethylene glycol production capacity has reached nearly half of the world's total.

[0003] Ethylene glycol production methods are mainly divided into two categories: petrochemical technology routes and syngas technology routes using natural gas or coal as raw materials. Domestically, integrated refining and chemical production primarily utilizes oil-based methods, supplemented by coal-based syngas routes, while ethane cracking accounts for only a small portion. Ethylene glycol produced via natural gas routes is of relatively lower quality. Specific preparation methods include ethylene oxide hydration, direct ethylene oxidation, ethylene carbonate esterification, syngas synthesis, methanol-formaldehyde synthesis, oxalate ester synthesis, and so on.

[0004] The industrial production method of ethylene glycol uses ethylene, oxygen, or air as raw materials. In the presence of a silver catalyst, methane or a nitrogen stabilizer, and a chloride inhibitor, ethylene is directly oxidized to ethylene oxide. Then, ethylene oxide and water in a specific molar ratio undergo a hydration reaction in a tubular reactor to produce ethylene glycol. The ethylene glycol solution is then concentrated by evaporation, dehydrated, and fractionated to obtain ethylene glycol and other diol byproducts. This industrial petroleum-based ethylene glycol production route uses ethylene as a raw material in a two-step process: first, ethylene is epoxidized to produce ethylene oxide, and then hydrated to produce ethylene glycol. For example, CN1437590A discloses a method in which ethylene is oxidized in the gas phase to ethylene oxide in the presence of a silver-based catalyst, and then the corresponding ethylene glycol and ethylene glycol ether are obtained through a subsequent reaction process. CN1807376A also discloses a production process system for preparing ethylene glycol from ethylene oxide, and makes some improvements to the ethylene oxide tubular fixed-bed reactor and the ethylene glycol evaporation system to solve problems such as equipment corrosion and coking.

[0005] Since the above conversion is a two-step continuous reaction process, it involves two catalytic reaction systems: selective oxidation and acid catalysis. The epoxidation of ethylene to ethylene oxide and the subsequent hydration of ethylene oxide are carried out separately because the reaction conditions for these two reactions differ significantly. The water required for the hydrolysis of ethylene oxide is added in the second step. The entire route involves high reaction temperatures, multiple separation steps, and a large amount of water that needs to be separated. This not only presents problems of complex process flow and high energy consumption, but also inevitably leads to deep oxidation of ethylene or ethylene oxide with oxygen at high temperatures, generating carbon dioxide and wasting carbon resources. The above two-step preparation process is relatively complex, energy-intensive, and the intermediates pose potential explosive hazards. Therefore, the technology for the one-step direct production of ethylene glycol from ethylene via catalysis has attracted considerable attention. This involves the one-step conversion of ethylene into ethylene glycol under the action of hydrogen peroxide and a catalyst system. For example, the method for directly preparing ethylene glycol by oxidizing ethylene with hydrogen peroxide disclosed in CN103172495A uses phosphotungstic heteropoly acid quaternary ammonium salt as a catalyst, which can realize the one-step synthesis of ethylene glycol from ethylene. However, the catalyst is easily soluble in the reaction mixture, which makes subsequent separation and recovery difficult.

[0006] The catalytic system coupled with titanium-silicon molecular sieves and hydrogen peroxide has certain advantages in the ethylene epoxidation reaction, exhibiting high activity and no pollution, thus attracting attention. For example, CN102951998A discloses a one-step method for preparing ethylene glycol from ethylene. Under oxidation reaction conditions and in the presence of a surfactant, ethylene, an aqueous hydrogen peroxide solution, and a catalyst containing titanium-silicon molecular sieves are contacted in an organic solvent to directly prepare ethylene glycol, achieving high conversion and selectivity. However, this method requires a large amount of organic solvent, easily causing pollution, and the utilization rate of hydrogen peroxide is not high. CN112851477A discloses a method for preparing ethylene glycol from ethylene oxidation in a slurry bed reactor. In the presence of a surfactant, ethylene, an aqueous hydrogen peroxide solution, a catalyst containing titanium-silicon molecular sieves, and an organic solvent are contacted and reacted in a slurry bed reactor. The mixed slurry undergoes solid-liquid separation, and liquid-phase membrane separation is used to obtain ethylene glycol. However, the product cannot be continuously separated, which is difficult and easily leads to serious side reactions. CN114394882A discloses a one-step method for producing ethylene glycol from ethylene, which involves contacting ethylene, hydrogen peroxide, and a titanium-silicon molecular sieve in water to perform an oxidative hydration reaction to obtain ethylene glycol. The acidic reaction conditions include homogeneous liquid acid and / or heterogeneous solid acid, resulting in high hydrogen peroxide utilization and high ethylene glycol selectivity and concentration. CN119977757A discloses a continuous method for producing ethylene glycol from ethylene, which involves adding a zinc-modified titanium-silicon molecular sieve catalyst and solvent to a batch reactor. By adjusting the pressure difference inside and outside the reactor, the liquid product is separated from the solid catalyst through a filter membrane inside the reactor, making it applicable to long-term continuous evaluation processes. Furthermore, CN115448817A discloses a one-step method for oxidizing ethylene to ethylene glycol using oxygen, a titanium-silicon molecular sieve heterogeneous catalyst, and coupled electrocatalysis and thermocatalysis. This method achieves high hydrogen peroxide utilization and ethylene glycol yield, and the catalyst's service life and cycle stability are increased through thermoforming.

[0007] In addition to the disclosed process and method improvements, existing technologies also disclose many improvements to catalysts and molecular sieves for one-step ethylene to ethylene glycol production. For example, CN116060123A discloses a niobium-modified titanium-silicon molecular sieve catalyst, which exhibits bifunctional catalytic effects in the ethylene oxidation and hydration processes. It can catalyze both ethylene epoxidation and ethylene oxide hydration, demonstrating good catalytic activity and selectivity. The coupling of these two processes enables one-step ethylene to ethylene glycol production, simplifying the current industrial process. CN113058643A discloses a technique for efficiently catalyzing one-step ethylene to ethylene glycol synthesis by modifying TS-1 molecular sieves with a combination of transition metal oxides and rare earth elements. CN117924021A discloses the preparation of tungsten-containing TS-1 molecular sieves, which are then modified with mixed rare earth elements and used as catalysts. Ethylene is introduced into a closed reactor and hydrogen peroxide is added dropwise to produce ethylene glycol, improving conversion rate and selectivity. CN105001058A discloses a method of modifying titanium-silicon molecular sieves by mixing them with aluminum salt solutions, followed by ultrasonication, rotary evaporation, and high-temperature calcination. This improves the acidity and oxygen transfer efficiency of the molecular sieves, facilitates the ring-opening of the intermediate ethylene oxide to obtain ethylene glycol, and enhances reaction efficiency and hydrogen peroxide utilization. Furthermore, no organic solvents are added, and the resulting product is an aqueous solution of ethylene glycol, which is beneficial for further product purification. The process is simple and energy-saving. CN102451763A mixes titanium-silicon molecular sieves, acidic molecular sieves, polyolefin monomers, and pore-forming agents, and polymerizes them in the presence of an initiator to obtain a blocky solid catalyst. This catalyst is then crushed, swollen with halogenated hydrocarbons, and activated by solvent extraction to obtain a shaped catalyst. This solves the problem of difficult separation between titanium-silicon catalyst powder and reaction liquid, and is particularly suitable for fixed-bed processes. CN102452900A also uses resin-bonded titanium-silicon molecular sieves and acidic molecular sieves to form a composite catalyst. Ethylene and hydrogen peroxide undergo direct epoxidation and hydration reactions in a fixed-bed reactor to obtain ethylene glycol in one step, improving reaction efficiency. However, these catalyst preparation methods require the use of large amounts of halogenated hydrocarbons and benzene compounds, resulting in significant pollution, long preparation processes, and complex procedures. CN114272955A also discloses a method for preparing core-shell magnetic titanium-silicon molecular sieve catalysts to achieve easy separation and recovery in the process, enabling efficient one-step catalytic synthesis of ethylene glycol from ethylene. CN120057939A utilizes ultrasonically dispersed titanium-silicon zeolite for photo-thermal tandem catalytic ethylene glycol synthesis, enhancing the adsorption of oxygen and ethylene, promoting mass transfer in water, and accelerating ethylene glycol synthesis.

[0008] In addition to using TS-1 molecular sieve catalysts, existing technologies also disclose MWW-type titanium-silicon molecular sieves as catalysts for the preparation of ethylene glycol from ethylene. For example, CN114797965A discloses a Ti-MWW molecular sieve catalyst; CN112642471A discloses a tin-doped Ti-MWW molecular sieve catalyst; and CN116984024A discloses a nitrogen-doped tungsten carbide / Ti-MWW molecular sieve catalyst. All of these are particularly suitable for the hydrogen peroxide hydration reaction of ethylene and hydrogen peroxide, achieving high hydrogen peroxide utilization and ethylene glycol yield.

[0009] Since its synthesis, TS-1 titanium-silicon molecular sieve has exhibited good catalytic activity in the field of catalytic oxidation. Its catalytic system coupled with hydrogen peroxide shows certain advantages over other catalysts in the ethylene epoxidation reaction: high activity and no pollution, it can directly catalyze the one-step production of ethylene glycol from ethylene, with mild reaction conditions, fewer byproducts, and fewer impurities in the gaseous products, allowing for direct recycling of ethylene. However, the catalytic activity of TS-1 molecular sieve in the EO hydration stage of the ethylene oxidation hydration reaction is relatively weak, mainly due to the weak acid catalytic active centers on it.

[0010] When this molecular sieve is used in catalyst molding and subsequent hydrothermal applications, it is difficult to guarantee its mechanical strength. When used in powder form, its small particle size poses significant challenges to the separation of the catalyst and product, with some particles even leaking through the pores of the filter medium, resulting in unnecessary consumption of expensive catalyst. Furthermore, its entry into the product material can cause further side reactions, increasing separation costs and affecting product quality. Existing embodiments often involve intermittent reactions in small laboratory reactors, and these issues also hinder the practical industrial application of titanium-silicon molecular sieves.

[0011] Therefore, in light of the current state of the technology, further attention needs to be paid to the problems in the one-step conversion method for ethylene glycol production from ethylene, such as the activity of epoxidation and hydration reactions, the diffusion performance of reactants, intermediates and products in the catalyst, solid-liquid separation of molecular sieves, and the continuous operation of the preparation process. Further improvements should be made to the selection of active components and corresponding catalysts and reactor types. Summary of the Invention

[0012] To address the aforementioned technical problems, the present invention aims to provide a conversion method for ethylene glycol production from ethylene. This method utilizes an organic template agent to incorporate modifying elements into the molecular sieve framework, including the synergistic effect of trace acidic additives during process operation. This allows for the regulation of the redox performance, acid catalytic performance, conversion activity, and reaction selectivity of the target product within the molecular sieve and catalyst. Furthermore, it improves the diffusion performance of reactants, intermediates, and products within the active components and catalyst, resulting in high catalytic conversion performance for the ethylene feedstock and high utilization of hydrogen peroxide. While achieving high conversion, the method reduces and suppresses side reactions, improves ethylene glycol selectivity, and saves process steps. Combined with a fixed-bed operation, this method facilitates continuous production and separation processes, making it more promising for practical industrial production.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] A method for converting ethylene to ethylene glycol, comprising the following steps:

[0015] Ethylene, hydrogen peroxide, and an acidic liquid additive were selected and applied at a concentration of 0.1–2.0 h. -1 After hydrogen peroxide liquid hourly space velocity enters the fixed bed reactor, it comes into contact with the mixed silicon support catalyst bed to carry out epoxidation and hydration reactions to obtain ethylene glycol.

[0016] The ethylene and hydrogen peroxide are mixed in a molar ratio of 1:(0.1-2);

[0017] The amount of the acidic liquid additive used, based on the total feed, is 50-100 ppm;

[0018] The mixed silicon-supported catalyst is composed of an acid-amine treated MFI structure titanium-silicon molecular sieve catalyst and a niobium-containing mesoporous MFI structure silicon molecular sieve catalyst in a weight ratio of 1:(0.05-0.2).

[0019] The solid content of niobium in the niobium-containing mesoporous MFI structured silica molecular sieve catalyst is 0.5–3 wt%. Preferably, the preparation method of the acid-amine treated MFI structured titanium-silicon molecular sieve catalyst is as follows:

[0020] On a dry basis, the acid-amine treated MFI structured titanium-silicon molecular sieve powder and silica sol are mixed at a weight ratio of 1:(1-1.5), shaped by extrusion, pelletizing, and shaping, dried, and then calcined at 540-570°C for 1-4 hours to obtain the product.

[0021] The acid-amine treated MFI structured titanium-silicon molecular sieve catalyst has a specific surface area of ​​100–300 m² / g and a pore volume of 0.1–0.4 mL / g.

[0022] Preferably, the preparation method of the acid-amine treated MFI structured titanium-silicon molecular sieve powder is as follows:

[0023] The synthesized MFI structured titanium silicate molecular sieve powder was selected and treated with a 0.5wt% to 3.5wt% acid solution for 2 to 5 hours at 20 to 90℃ and a liquid-solid ratio of 10 to 40.

[0024] Then, use a 0.1 wt% to 1 wt% tetrapropylammonium hydroxide solution, at a liquid-to-solid ratio of 15 to 30 and a temperature of 130 to 180°C, for hydrothermal treatment for 0.1 to 6 days, followed by filtration, washing, and drying to obtain the final product.

[0025] The acid solution is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, and fluorosilicic acid.

[0026] Preferably, the method for preparing the synthesized MFI structured titanium-silicon molecular sieve powder is as follows:

[0027] A homogeneous titanium silicate sol is prepared by hydrolysis, mixing, and stirring of a mixture of organic amine / SiO2 (molar ratio) of 0.1–0.6, SiO2 / TiO2 of 35–65, and H2O / SiO2 of 20–100, with tetrapropylammonium hydroxide, tetraethyl orthosilicate, and tetrabutyl titanate in a mixed alcohol solvent. After removing the alcohol by heating, the sol is hydrothermally crystallized at 130–180°C for 1–6 days to obtain the final product.

[0028] The mixed alcohol solvent is a polyether polyol and / or isopropanol.

[0029] Preferably, the preparation method of the niobium-containing mesoporous MFI structured silica molecular sieve catalyst is as follows:

[0030] On a dry basis, the synthesized niobium-containing mesoporous MFI structured silica molecular sieve powder and silica sol are mixed at a weight ratio of 1:(0.25~0.45), then shaped by extrusion, pelletizing and shaping, and dried and calcined at 450~580℃ for 0.5~6 hours to obtain the product.

[0031] The niobium-containing mesoporous MFI structured silicon molecular sieve catalyst has a specific surface area of ​​100–350 m² / g and a pore volume of 0.1–0.3 mL / g.

[0032] Preferably, the method for preparing the synthesized niobium-containing mesoporous MFI structured silica molecular sieve powder is as follows:

[0033] The following formula is used: organic amine / SiO2 = 0.1-0.2, SiO2 / NbO2 = 50-100, H2O / SiO2 = 4-20. 80-120 mesh silica gel powder, tetrapropylammonium hydroxide, niobium oxide, and water are mixed to form a homogeneous colloid. This colloid is then hydrothermally crystallized at 130-180℃ for 1-6 days to obtain the final product.

[0034] Preferably, the ethylene is pure ethylene or dilute ethylene from refinery dry gas, with a volume concentration of 15% to 100%.

[0035] The concentration of the hydrogen peroxide is 30wt% to 70wt%.

[0036] The acidic liquid additive includes one or more of phosphoric acid, hydrochloric acid, sulfuric acid, and perchloric acid.

[0037] Preferably, the solid content of niobium in the niobium-containing mesoporous MFI structured silica molecular sieve catalyst is 0.5–1.5 wt%.

[0038] Preferably, the reaction temperature in the fixed-bed reactor is 50–85°C and the pressure is 0.5–1.5 MPa.

[0039] Preferably, the fixed-bed reactor is a vertical tube reactor with a height-to-diameter ratio of 60 to 275 for a single tube.

[0040] Beneficial effects:

[0041] This invention provides a method for converting ethylene to ethylene glycol. It involves using an organic template agent to incorporate modifying elements into a molecular sieve framework, including the synergistic effect of trace acidic additives during process operation. This regulates the redox performance, acid catalytic performance, conversion activity, and reaction selectivity of the target product in the molecular sieve and catalyst. Furthermore, it improves the diffusion performance of reactants, intermediates, and products within the active components and catalyst, resulting in high catalytic conversion performance of the ethylene feedstock and high utilization of hydrogen peroxide. While achieving high conversion, the method reduces and suppresses side reactions, improves ethylene glycol selectivity, and saves process steps. Combined with a fixed-bed operation, this method facilitates continuous production and separation processes, making it highly promising for practical industrial production.

[0042] This ethylene-to-ethylene glycol conversion technology features high ethylene conversion efficiency, good product selectivity, and high hydrogen peroxide utilization, while reducing production steps. Combined with a fixed-bed method, it has greater prospects for industrial implementation. Detailed Implementation

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly described below in conjunction with the description of the embodiments or the prior art. It should be noted that the description of these embodiments is for the purpose of helping to understand the present invention, but does not constitute a limitation of the present invention.

[0044] One specific embodiment of the present invention is as follows:

[0045] All the chemicals mentioned in this invention are readily available through commercial purchase.

[0046] As is well known to those skilled in the art, the conversion method, active components and catalysts, operating steps, and reactor form constitute the content, features, and system of this invention, distinguishing it from existing technologies. These are the most important factors affecting the one-step catalytic conversion of ethylene to the target product ethylene glycol. Because the interactions between these factors face significant uncertainty and do not exhibit a simple linear relationship, it is difficult to obtain direct inspiration from existing technologies, nor is it easy to achieve the desired technical objectives and effects through simple permutation and combination experiments based on existing technologies.

[0047] This technical solution does not limit the geometric dimensions of the solid granular titanium-silicon catalyst, but requires reasonable matching based on the reactor dimensions.

[0048] In this technical solution, the amount of mixed alcohol is not strictly limited, and it will evaporate from the titanium silica sol during heating and alcohol removal.

[0049] This technical solution does not limit the geometric dimensions of the solid granular niobium-silicon catalyst, but uses the same dimensions as the aforementioned titanium-silicon catalyst.

[0050] The fixed-bed reactor used in this technical solution is a vertical tube reactor, with a height-to-diameter ratio of 60 to 275 for a single tube.

[0051] In the examples, gas chromatography was used to analyze the components in the system. Other detection methods can be found in (National Standard for Test Methods of Petroleum and Petroleum Products, published by China Standards Press, 1989) and (Analytical Methods for Petrochemical Products (RIPP Test Methods), published by Science Press, 1990).

[0052] Among them, tetrapropylamine hydroxide, chemically pure, 40 wt%, Beijing Daxing Xingfu Chemical Reagent Research Institute.

[0053] Niobium pentoxide, chemically pure, Beijing Chemical Reagent Company.

[0054] Example 1:

[0055] This embodiment prepares the acid-amine treated MFI structured titanium-silicon molecular sieve silicon support catalyst of the present invention.

[0056] With a molar ratio of SiO2:0.02TiO2:0.4TPAOH:60H2O, the calculated amounts of tetrapropylammonium hydroxide (chemically pure, 40wt%, Beijing Daxing Xingfu Chemical Reagent Research Institute), tetraethyl orthosilicate, and tetrabutyl titanate were hydrolyzed and mixed in a mixed alcohol solvent of polyether polyol and isopropanol, stirred to form a uniform titanium silicate sol, heated to remove alcohol, and then hydrothermally crystallized at 170°C for 20-30 hours in a stainless steel reactor with a polytetrafluoroethylene liner. After filtration, washing with deionized water, and drying, the sol was then subjected to further treatment.

[0057] After being treated with 0.5 wt% phosphoric acid solution at 90 °C for 4 hours, the product was hydrothermally activated in an autoclave at 180 °C for 16 hours with 1 wt% tetrapropylammonium hydroxide solution. After filtration, washing and drying, the product was calcined at 550 °C for 4 hours. X-ray diffraction data showed that the product was a titanium-silicon molecular sieve with an MFI structure.

[0058] Referring to the catalyst extrusion, pelletizing, and shaping methods and steps described in "Catalyst Production - Laboratory and Industrial Preparation" by [US] AB Stellens, granular silicon supported catalysts were prepared using silica sol (SiO2 20wt%, Sichuan Runhe Catalytic Materials Co., Ltd., China) as a binder, with a molecular sieve content of 50wt% on a dry basis. The shaped catalysts were activated by calcining at 550℃ for 4 hours in a muffle furnace, resulting in an acid-amine treated MFI structure titanium-silicon molecular sieve supported catalyst with a specific surface area of ​​170 m² / g and a pore volume of 0.11 mL / g.

[0059] Example 2:

[0060] This embodiment prepares a silicon-supported catalyst for a niobium-containing mesoporous MFI structured silicon molecular sieve, as described in this invention.

[0061] According to the ratio of SiO2:0.015NbO2:0.16TPAOH:38H2O, the calculated amounts of tetrapropylammonium hydroxide aqueous solution (as above) and niobium pentoxide (chemically pure, Beijing Chemical Reagent Company) were weighed and dissolved in deionized water. The calculated amount of silica sol (industrial grade, SiO2 20wt%, Qingdao Ocean Chemical) was added. After stirring and mixing evenly at room temperature, the resulting reaction mixture was placed in a stainless steel reactor with a polytetrafluoroethylene liner and crystallized at 130℃ for 5 days. After filtration and washing, the crystallized product was obtained. X-ray diffraction data showed that the product was a silicon molecular sieve with an MFI structure. Low-temperature nitrogen adsorption analysis showed that it had a mesoporous structure with a pore size of 4 nanometers.

[0062] Referring to the molding preparation method and steps of Example 1, granular silicon supported catalyst was prepared using silica sol (as above) as a binder, with a molecular sieve content of 60 wt% on a dry basis. The shaped catalyst was activated by calcining at 550°C for 4 hours in a muffle furnace. A niobium-containing mesoporous MFI structure silicon molecular sieve supported catalyst was obtained, with a specific surface area of ​​204 m² / g, a pore volume of 0.12 mL / g, and a niobium content of 1.01 wt%.

[0063] Comparative Example 1:

[0064] This comparative example uses the titanium-silicon molecular sieve synthesis method of the classic literature USP4410501 in the prior art. Following its preparation content and the steps in the examples, TS-1 titanium-silicon molecular sieve was prepared. In order to be as close as possible to the examples of the present invention and to have comparability, the TS-1 titanium-silicon molecular sieve silicon support catalyst of Comparative Example 1 was prepared according to the same weight ratio of molecular sieve and silica sol to catalyst in Example 1 of the present invention, as well as the catalyst forming preparation and activation method.

[0065] Comparative Example 2:

[0066] This comparative example uses the silicon molecular sieve synthesis method from the classic literature USP4061724 in the prior art. Following its preparation content and the steps in the examples, Silicalite-1 silicon molecular sieve was prepared. For the same reason, according to the weight ratio of molecular sieve and silica sol to catalyst in Example 2 of this invention, as well as the catalyst forming preparation and activation method, the Silicalite-1 silicon molecular sieve silicon support catalyst of Comparative Example 2 was prepared.

[0067] Example 3:

[0068] A method for preparing ethylene glycol from ethylene:

[0069] According to the conversion method and reactor configuration described in this invention, pure ethylene and industrial dilute ethylene, industrial hydrogen peroxide and phosphoric acid are used as raw materials, respectively.

[0070] A 50 ml vertical tubular reactor with a height-to-diameter ratio of 60 was used; the catalyst particles had a diameter of 2 mm; the reactor bed temperature was 80℃ and the system pressure was 0.1 MPa.

[0071] The reactor feed was calculated based on a volumetric hourly space velocity (VHSV) of 0.2 h⁻¹ (calculated as hydrogen peroxide). -1 The molar ratio of ethylene to hydrogen peroxide is 1.0, and the phosphoric acid content is 100 micrograms per gram of the total feed.

[0072] Table 1 Comparison of Operation Results of Fixed-Bed Reactor for Ethylene Conversion to Ethylene Glycol Production

[0073]

[0074] The one-step ethylene-to-ethylene glycol conversion method provided by this invention, including a catalyst and reactor configuration, demonstrates superior performance compared to typical prior art conversion methods and molecular sieve catalyst preparation technologies in a fixed-bed reactor. This method, including the active component and catalyst, exhibits better implementation results. It boasts superior catalytic performance, conversion efficiency, and ethylene glycol product selectivity, along with high hydrogen peroxide utilization, thereby reducing energy consumption throughout the entire process. These achievements suggest that this green production technology has a promising future for continuous production applications.

[0075] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for converting ethylene to ethylene glycol, characterized in that, The specific steps include: Ethylene, hydrogen peroxide, and an acidic liquid additive were selected and applied at a concentration of 0.1–2.0 h. -1 After hydrogen peroxide liquid hourly space velocity enters the fixed bed reactor, it comes into contact with the mixed silicon support catalyst bed to carry out epoxidation and hydration reactions to obtain ethylene glycol. The ethylene and hydrogen peroxide are mixed in a molar ratio of 1:(0.1-2); The amount of the acidic liquid additive used, based on the total feed, is 50-100 ppm; The mixed silicon-supported catalyst is composed of an acid-amine treated MFI structure titanium-silicon molecular sieve catalyst and a niobium-containing mesoporous MFI structure silicon molecular sieve catalyst in a weight ratio of 1:(0.05-0.2). The solid content of niobium in the niobium-containing mesoporous MFI structured silica molecular sieve catalyst is 0.5–3 wt%.

2. The method for converting ethylene to ethylene glycol according to claim 1, characterized in that, The preparation method of the acid-amine treated MFI structured titanium-silicon molecular sieve catalyst is as follows: On a dry basis, the acid-amine treated MFI structured titanium-silicon molecular sieve powder and silica sol were mixed at a weight ratio of 1: (1~1.5) After mixing and kneading, the mixture is shaped by extrusion, pelletizing, and shaping. After drying, it is calcined at 540~570℃ for 1~4 hours to obtain the final product. The acid-amine treated MFI structured titanium-silicon molecular sieve catalyst has a specific surface area of ​​100–300 m² / g and a pore volume of 0.1–0.4 mL / g.

3. The method for converting ethylene to ethylene glycol according to claim 2, characterized in that, The preparation method of the MFI structured titanium-silicon molecular sieve powder after acid amine treatment is as follows: The synthesized MFI structured titanium silicate molecular sieve powder was selected and treated with a 0.5wt% to 3.5wt% acid solution for 2 to 5 hours at 20 to 90℃ and a liquid-solid ratio of 10 to 40. Then, use a 0.1 wt% to 1 wt% tetrapropylammonium hydroxide solution, at a liquid-to-solid ratio of 15 to 30 and a temperature of 130 to 180°C, for hydrothermal treatment for 0.1 to 6 days, followed by filtration, washing, and drying to obtain the final product. The acid solution is one or more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, and fluorosilicic acid.

4. The method for converting ethylene to ethylene glycol according to claim 3, characterized in that, The preparation method of the synthesized MFI structured titanium-silicon molecular sieve powder is as follows: A homogeneous titanium silicate sol is prepared by hydrolysis, mixing, and stirring of a mixture of organic amine / SiO2 (molar ratio) of 0.1–0.6, SiO2 / TiO2 of 35–65, and H2O / SiO2 of 20–100, with tetrapropylammonium hydroxide, tetraethyl orthosilicate, and tetrabutyl titanate in a mixed alcohol solvent. After removing the alcohol by heating, the sol is hydrothermally crystallized at 130–180°C for 1–6 days to obtain the final product. The mixed alcohol solvent is a polyether polyol and / or isopropanol.

5. The method for converting ethylene to ethylene glycol according to claim 1, characterized in that, The preparation method of niobium-containing mesoporous MFI structured silica molecular sieve catalyst is as follows: On a dry basis, the synthesized niobium-containing mesoporous MFI structured silica molecular sieve powder and silica sol were mixed at a weight ratio of 1: After mixing (0.25~0.45), the mixture is shaped by extrusion, pelletizing, and shaping. After drying, it is calcined at 450~580℃ for 0.5~6 hours to obtain the final product. The niobium-containing mesoporous MFI structured silicon molecular sieve catalyst has a specific surface area of ​​100–350 m² / g and a pore volume of 0.1–0.3 mL / g.

6. The method for converting ethylene to ethylene glycol according to claim 5, characterized in that, The method for preparing the synthesized niobium-containing mesoporous MFI structured silicon molecular sieve powder is as follows: The following formula is used: organic amine / SiO2 = 0.1-0.2, SiO2 / NbO2 = 50-100, H2O / SiO2 = 4-20. 80-120 mesh silica gel powder, tetrapropylammonium hydroxide, niobium oxide, and water are mixed to form a homogeneous colloid. This colloid is then hydrothermally crystallized at 130-180℃ for 1-6 days to obtain the final product.

7. The method for converting ethylene to ethylene glycol according to claim 1, characterized in that, The ethylene is pure ethylene or dilute ethylene from refinery dry gas, with a volume concentration of 15% to 100%. The concentration of the hydrogen peroxide is 30wt% to 70wt%. The acidic liquid additive includes one or more of phosphoric acid, hydrochloric acid, sulfuric acid, and perchloric acid.

8. The method for converting ethylene to ethylene glycol according to claim 1, characterized in that, The solid content of niobium in the niobium-containing mesoporous MFI structured silica molecular sieve catalyst is 0.5–1.5 wt%.

9. The method for converting ethylene to ethylene glycol according to claim 1, characterized in that, The reaction temperature in the fixed-bed reactor is 50–85°C, and the pressure is 0.5–1.5 MPa.

10. The method for converting ethylene to ethylene glycol according to claim 9, characterized in that, The fixed-bed reactor is a vertical tube reactor with a height-to-diameter ratio of 60 to 275 for a single tube.

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