A catalyst for ethylene oxide production, its preparation method and application

Abstract

The application discloses a catalyst for preparing ethylene oxide and a preparation method and application thereof. The catalyst comprises a carrier, a main catalyst and a cocatalyst. The carrier is Ta3C2, the main catalyst is Ag element, and the cocatalyst is Ta2O5. The main catalyst accounts for 10-50 wt% of the mass of the catalyst, the cocatalyst accounts for 5-10 wt% of the mass of the catalyst, and the rest is the carrier. The catalyst can be applied to the reaction for preparing ethylene oxide, and the selectivity of the generated ethylene oxide is improved, the reaction speed is fast, the yield is high, and the catalyst can be applied to large-scale production. The catalyst preparation method is stable, controllable and good in reproducibility.

Description

Technical Field

[0001] This application relates to a catalyst for the preparation of ethylene oxide, its preparation method, and its application, belonging to the field of chemical engineering. Background Technology

[0002] Ethylene oxide (EO) is an important petrochemical intermediate, widely used in the synthesis of ethylene glycol and other polyols. Industrially, production primarily involves the direct reaction of ethylene with oxygen, with most production facilities also equipped with ethylene oxide hydration processes to produce ethylene glycol (EG). Ethylene glycol's main uses are in the synthesis of polyester fibers, bottle resins, films, antifreeze, and coolants. In recent years, my country's polyester industry has developed rapidly, leading to a surge in demand for ethylene glycol. Consequently, my country's ethylene oxide / ethylene glycol production capacity and output have increased year by year, expanding the demand for silver catalysts for the oxidation of ethylene to ethylene oxide.

[0003] The research and development focus of ethylene oxidation to produce low-carbon oxygen-containing compounds (ethylene oxide) technology is on catalysts. Currently, there are three types of industrial catalysts: highly active silver catalysts; moderately selective catalysts; and highly selective silver catalysts. Foreign companies providing silver catalyst technology for ethylene oxide mainly include Shell, Scientific Design (SD), Dow Chemical, and Nippon Shokubai. Domestically, the YS series silver catalysts (YS-4, YS-5, YS-6) developed by Sinopec's Yanshan Branch have performance comparable to similar foreign catalysts. Furthermore, its recently developed YS-7, YS-8520, and YS-8810 silver catalysts exhibit good performance and have achieved excellent application results in China. Summary of the Invention

[0004] This project employs an impregnation method to prepare highly selective silver catalysts, using Ta3C2 as the support, Ag as the main catalyst, and Ta2O5 as the co-catalyst to improve catalyst activity and stability. These highly selective silver catalysts meet market demands and have significant practical and economic benefits in reducing production costs and promoting the development of the domestic petrochemical industry.

[0005] According to one aspect of this application, a catalyst for the preparation of ethylene oxide is provided, said catalyst comprising a support, a main catalyst, and a co-catalyst;

[0006] The carrier is Ta3C2;

[0007] The main catalyst is elemental Ag.

[0008] The co-catalyst is Ta2O5;

[0009] The main catalyst accounts for 10 to 50 wt% of the mass of the catalyst;

[0010] Optionally, the main catalyst accounts for any value of 10wt%, 20wt%, 30wt%, 40wt%, or 50wt% of the total catalyst mass, or a range between any two.

[0011] The co-catalyst accounts for 5 to 10 wt% of the mass of the catalyst;

[0012] Optionally, the co-catalyst accounts for any value of 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, or 10 wt% of the mass of the catalyst, or a range between any two.

[0013] The rest are the carriers.

[0014] According to another aspect of this application, a method for preparing the above-described catalyst is provided.

[0015] The preparation method includes preparing Ta3AlC2 by high-temperature calcination, then soaking Ta3AlC2 in hydrofluoric acid solution and mixing, washing several times and drying to obtain Ta3C2, mixing Ta3C2 and sodium tetrafluoroborate in hydrochloric acid solution and then carrying out a hydrothermal reaction, washing and drying to obtain Ta2O5 / Ta3C2. Finally, impregnating Ta2O5 / Ta3C2 with silver amine solution and then decomposing the silver amine complex into metallic silver by steam activation to obtain the catalyst.

[0016] Specifically, the following steps are included:

[0017] (1) Mix the raw materials containing Ta3C2 and the oxidant to undergo a hydrothermal reaction to obtain Ta2O5 / Ta3C2;

[0018] (2) The Ta2O5 / Ta3C2 obtained in (1) is immersed in silver ammonia solution, left to stand, and calcined (under Ar atmosphere) to obtain the catalyst.

[0019] (1)

[0020] The oxidant is selected from sodium tetrafluoroborate;

[0021] The mass ratio of Ta3C2 to the oxidant is 1:(0.5~1);

[0022] Optionally, the mass ratio of Ta3C2 to the oxidant is any value from 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1 or any range between the two.

[0023] The mixing is performed in a hydrochloric acid solution;

[0024] The concentration of the hydrochloric acid solution is 0.1M to 1M;

[0025] Optionally, the concentration of the hydrochloric acid solution is any value or a range between 0.1M, 0.2M, 0.3M, 0.4M, 0.5M, 0.6M, 0.7M, 0.8M, 0.9M, and 1M.

[0026] The solid-liquid ratio of the raw material containing Ta3C2 and oxidant to the hydrochloric acid solution is 1:(40~70)g / ml;

[0027] Optionally, the solid-liquid ratio of the solid raw material containing Ta3C2 and the oxidant to the hydrochloric acid solution is any value among 1:40 g / ml, 1:50 g / ml, 1:60 g / ml, and 1:70 g / ml, or any range between two of them.

[0028] The temperature of the hydrothermal reaction is 100–140°C;

[0029] Optionally, the temperature of the hydrothermal reaction is any value among 100℃, 110℃, 120℃, 130℃, and 140℃, or a range between any two.

[0030] The hydrothermal reaction takes 2 to 8 hours.

[0031] Optionally, the hydrothermal reaction time is any value among 2h, 3h, 4h, 5h, 6h, 7h, and 8h, or a range between any two.

[0032] The Ta2O5 / Ta3C2 is dried (I);

[0033] The temperature of the drying process I is 60–100°C;

[0034] Optionally, the temperature of the drying I is any value among 60°C, 70°C, 80°C, 90°C, and 100°C, or a range between any two.

[0035] The drying time for step I is 12–36 hours.

[0036] Optionally, the drying time I is any value among 12h, 18h, 24h, 30h, and 36h, or a range between any two.

[0037] The Ta2O5 / Ta3C2 is washed I;

[0038] The solvent used in the washing process I is selected from at least one of deionized water, ethanol, and a mixed solution of deionized water and ethanol.

[0039] (2)

[0040] The solid-liquid ratio of Ta2O5 / Ta3C2 to the silver ammonia solution is 1:(40~100)g / ml;

[0041] Optionally, the solid-liquid ratio of the Ta2O5 / Ta3C2 to the silver ammonia solution is any value among 1:40g / ml, 1:50g / ml, 1:60g / ml, 1:70g / ml, 1:80g / ml, 1:90g / ml, and 1:100g / ml, or any range between the two.

[0042] The settling time is 30 to 60 minutes;

[0043] Optionally, the reaction is allowed to stand for any value among 30 min, 40 min, 50 min, and 60 min, or any range between two of these values.

[0044] The vacuum degree of the reaction is 5-15 mmHg;

[0045] Optionally, the vacuum degree of the reaction is any value among 5 mmHg, 10 mmHg, and 15 mmHg, or a range between any two.

[0046] The calcination I (carried out in an Ar atmosphere) is performed at a temperature of 100–200 °C.

[0047] Optionally, the temperature of the calcination I (carried out in an Ar atmosphere) is any value or a range between 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, and 200°C.

[0048] The calcination I (carried out in an Ar atmosphere) takes 2 to 60 minutes.

[0049] Optionally, the calcination I (carried out in an Ar atmosphere) time is any value among 2 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min, or a range between any two.

[0050] The concentration of silver ions in the silver ammonia solution is 2–5 M.

[0051] Optionally, the concentration of silver ions in the silver ammonia solution is any value among 2M, 3M, 4M, and 5M, or a range between any two.

[0052] The silver ammonia solution includes silver oxalate, ethylenediamine, ethanolamine, and water;

[0053] The molar ratio of silver oxalate, ethylenediamine, ethanolamine and water is 1:(1-2):(1-2):(20-30).

[0054] The catalyst is also dried (II);

[0055] The temperature of the drying II process is 100–120°C;

[0056] Optionally, the temperature of the drying II is any value among 100°C, 110°C, and 120°C, or a range between any two.

[0057] The drying time for step II is 8–12 hours.

[0058] Optionally, the drying time II is any value among 8h, 9h, 10h, 11h, and 12h, or a range between any two.

[0059] The silver ammonia solution is obtained through the following process:

[0060] A certain amount of silver nitrate solution was added to deionized water I. After heating deionized water I to 50°C, ammonium oxalate (molar ratio of silver nitrate to ammonium oxalate 2:1) was added. The two solutions reacted to form a white precipitate of silver oxalate. After a period of time, the solution was washed with deionized water until nitrate ions were no longer present. Deionized water II, a certain amount of ethylenediamine, and ethanolamine were added to the filtered cake. After continuous stirring, the filter cake completely dissolved, yielding a silveramine solution.

[0061] The volume ratio of silver nitrate to deionized water I is 1:(3-5).

[0062] The molar ratio of silver oxalate, ethylenediamine, ethanolamine and deionized water II is 1:(1-2):(1-2):(20-30).

[0063] The impregnation is a vacuum impregnation, which includes the following process:

[0064] The Ta2O5 / Ta3C2 was placed in a vacuum container, and a vacuum pump was used to evacuate the container. Silver amine solution was poured into the Ta2O5 / Ta3C2 using an excess impregnation method. After standing for a period of time, the excess solution was filtered off. The container was dried overnight and then calcined in an Ar atmosphere for a period of time to obtain the catalyst.

[0065] The Ta3C2 is obtained through the following process: Ta3AlC2 is prepared by high-temperature calcination, and then Ta3AlC2 is soaked in hydrofluoric acid solution and mixed, washed several times and dried to obtain Ta3C2.

[0066] The specific steps for preparing Ta3AlC2 by the high-temperature calcination method include:

[0067] 1) Grind the tantalum source, aluminum source, and carbon powder to obtain a mixture;

[0068] 2) Calcine the mixture obtained in step 1) of II to obtain Ta3AlC2;

[0069] The tantalum source is selected from tantalum powder;

[0070] The aluminum source is selected from aluminum powder.

[0071] The molar ratio of the tantalum source, aluminum source and carbon powder is 3:(0.9~1):2;

[0072] The upper limit of the molar ratio of the tantalum source, aluminum source and carbon powder is selected from 3:0.9:2, and the lower limit is selected from 3:1:2.

[0073] The calcination temperature in step 2) is 1000℃~1400℃, and the calcination time is 1~6h;

[0074] In step 2), the upper limit of the calcination II temperature is selected from 1400℃, 1300℃, and 1200℃, and the lower limit of the calcination I temperature is selected from 1000℃, 1100℃, and 1200℃; the upper limit of the calcination II time is selected from 6h, 5h, and 4h, and the lower limit of the calcination II time is selected from 1h, 2h, and 3h.

[0075] During the process of soaking Ta3AlC2 in hydrofluoric acid solution and mixing

[0076] The concentration of the hydrofluoric acid solution is 30-50 wt%.

[0077] The upper limit of the concentration of the hydrofluoric acid solution is selected from 50 wt% and 40 wt%, and the lower limit is selected from 30 wt% and 40 wt%.

[0078] The solid-liquid ratio of the Ta3AlC2 and hydrofluoric acid solution is 1:(10~30)g / ml;

[0079] The upper limit of the solid-liquid ratio of the Ta3AlC2 and hydrofluoric acid solution is selected from 1:10g / ml and 1:20g / ml, and the lower limit is selected from 1:30g / ml and 1:20g / ml.

[0080] The soaking temperature is 40℃~80℃;

[0081] The soaking time is 28–112 hours;

[0082] The upper limit of the soaking temperature is selected from 80℃, 70℃, and 60℃, and the lower limit is selected from 40℃, 50℃, and 60℃; the upper limit of the soaking time is selected from 112h and 84h, and the lower limit is selected from 28h and 56h.

[0083] The solvent used in Wash II is selected from at least one of deionized water, ethanol, and a mixed solution of deionized water and ethanol;

[0084] The drying temperature is 60℃~100℃, and the drying time is 12~36h.

[0085] The upper limit of the drying temperature is selected from 100℃, 90℃, and 80℃, and the lower limit is selected from 60℃, 70℃, and 80℃; the upper limit of the drying time is selected from 36h and 24h, and the lower limit is selected from 12h and 24h.

[0086] According to another aspect of this application, a method for preparing ethylene oxide is provided, comprising the following steps:

[0087] A material containing oxygen and ethylene is introduced into the reactor, where it comes into contact with the catalyst and reacts to obtain a product containing ethylene oxide.

[0088] The catalyst is either the catalyst described above or a catalyst prepared by the preparation method described above.

[0089] The volume hourly space velocity of the material is 2500–5000 h⁻¹. -1 ;

[0090] The upper limit of the volumetric hourly space velocity of the material is selected from 5000 h. -1 4000h -1 The lower limit is selected from 2500h -1 3000h -1 .

[0091] In the material, the molar ratio of oxygen to ethylene is 1:10 to 15.

[0092] The reaction temperature is 230–270°C;

[0093] The upper limit of the reaction temperature is selected from 270℃, 260℃, and 250℃, and the lower limit is selected from 230℃, 240℃, and 250℃.

[0094] The reaction time is 3–6 hours;

[0095] The upper limit of the reaction time is selected from 6h and 5h, and the lower limit is selected from 3h and 4h.

[0096] The reaction is carried out at a pressure of 1–3 MPa.

[0097] The upper limit of the reaction pressure is selected from 3 MPa and 2 MPa, and the lower limit is selected from 1 MPa and 2 MPa.

[0098] The reactor is a fixed-bed reactor.

[0099] The catalyst is packed into the fixed-bed reactor.

[0100] The beneficial effects that this application can produce include:

[0101] 1) The catalyst provided in this application can be applied to the reaction for preparing ethylene oxide and improve the selectivity of the generated ethylene oxide.

[0102] 2) The preparation method of the catalyst provided in this application is stable, controllable, and reproducible.

[0103] 3) The method for preparing ethylene oxide by oxidation provided in this application uses the catalyst provided in this application, which has a fast reaction rate and high yield, and can be applied to large-scale production. Attached Figure Description

[0104] Figure 1 Catalyst 1 # X-ray powder diffraction pattern of Ta2O5 / Ta3C2.

[0105] Figure 2 Catalyst 1 # Scanning electron microscope image of Ta2O5 / Ta3C2. Detailed Implementation

[0106] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0107] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially. The gas chromatograph used was an Agilent 7890B gas chromatograph.

[0108] Examples 1-28

[0109] Preparation of catalysts

[0110] Taking item 1 in Table 1 as an example, tantalum powder, aluminum powder, and carbon powder in a molar ratio of 3:1:2 were ground to obtain a mixture. The mixture was calcined at 1400℃ for 2 hours to obtain Ta3AlC2. Ta3AlC2 was then soaked in a 40wt% hydrofluoric acid solution at 60℃ for 56 hours (the solid-liquid ratio of Ta3AlC2 to hydrofluoric acid solution was 1:20 g / ml). After washing several times with ethanol, it was dried in an oven at 70℃ for 24 hours to obtain Ta3C2. Ta3... C2 and sodium tetrafluoroborate were mixed in a 0.1M hydrochloric acid solution (solid-liquid ratio 1:50), and then subjected to a hydrothermal reaction at 120℃ for 4 hours. After washing several times with ethanol, the mixture was dried in an oven at 70℃ for 24 hours to obtain Ta2O5 / Ta3C2. A certain amount of silver nitrate solution (volume ratio 1:5) was added to deionized water I. After heating deionized water I to 50℃, ammonium oxalate (molar ratio of silver nitrate to ammonium oxalate 2:1) was added. The two solutions reacted to form a white silver oxalate precipitate. After a period of time, the mixture was washed with deionized water until nitrate ions were no longer present. Deionized water II, ethylenediamine, and ethanolamine (the molar ratio of silver oxalate, ethylenediamine, ethanolamine, and deionized water II is 1:2:2:30) were added to the filtered cake. After continuous stirring, the filter cake was completely dissolved, yielding a silver amine solution. Ta₂O₅ / Ta₃C₂ was placed in a vacuum container and evacuated using a vacuum pump (vacuum degree 9 mmHg). The silver amine solution was poured into the prepared Ta₂O₅ / Ta₃C₂ and allowed to stand for 30 min. Excess solution was filtered off. The mixture was dried at 100℃ for 10 h and calcined at 180℃ in an Ar atmosphere for 40 min to obtain the Ag / Ta₂O₅ / Ta₃C₂ catalyst (Ag accounts for 20 wt% of the catalyst mass). This catalyst is designated as catalyst 1. # .

[0111] Following the steps below, adjust the type and amount of each raw material and the reaction parameters to obtain a series of catalysts numbered 2 to 28, denoted as catalyst 2. # ~Catalyst 28 # As shown in Tables 1-3 below:

[0112] Table 1

[0113]

[0114] Table 2

[0115]

[0116] Table 3

[0117]

[0118]

[0119] The explanations for columns 1 to 3 above are as follows:

[0120] Tantalum source: Tantalum powder (Ta1).

[0121] Aluminum source: Aluminum powder (Al1).

[0122] Toner (C1).

[0123] Calcination I: Calcination during the preparation of Ag / Ta2O5 / Ta3C2 catalyst (carried out in an Ar atmosphere).

[0124] Calcination II: Calcination during the preparation of Ta3AlC2.

[0125] Solvents for washing I: deionized water (solution 1), ethanol (solution 2), and a mixed solution of deionized water and ethanol (solution 3).

[0126] Solvents for Washing II: Deionized water (solution 1), ethanol (solution 2), and a mixed solution of deionized water and ethanol (solution 3).

[0127] Drying: Drying during the preparation of Ta3AlC2.

[0128] Drying I: Drying during the preparation of Ta2O5 / Ta3C2.

[0129] Drying II: Drying during the preparation of Ag / Ta2O5 / Ta3C2 catalyst.

[0130] XRD characterization

[0131] The catalyst 1 was analyzed using a Miniflex 600 X-ray diffractometer with a Cu target. # Powder diffraction of Ta2O5 / Ta3C2 yielded catalyst 1. # The diffraction peaks of Ta2O5 / Ta3C2 conform to the characteristic peaks of Ta2O5 / Ta3C2 (e.g., Figure 1 (As shown).

[0132] SEM characterization

[0133] Scanning electron microscopy (SEM) (JSM-7800F) on catalyst 1 # Morphological analysis of Ta2O5 / Ta3C2 (e.g.) Figure 2 As shown in the figure, Ta2O5 / Ta3C2 exhibits a lamellar structure after hydrothermal reaction.

[0134] Application Example 1

[0135] The catalyst is used in the oxidation reaction to prepare low-carbon oxygen-containing compounds (ethylene oxide).

[0136] Catalysts 1-28 prepared in Examples 1-28# ~Catalyst 28 # It is used in the oxidation process to prepare ethylene oxide at a reaction temperature of 230℃, a reaction pressure of 2 MPa, a reaction time of 5 h, and a volume hourly space velocity of 4000 h⁻¹. -1 .

[0137] Composition of reactant gases (mol%)

[0138] Ethylene (C2H4) 28.0% ± 1.0%

[0139] Oxygen (O2) 2.4% ± 0.2%

[0140] Carbon dioxide (CO2) < 1.0%

[0141] Stabilizing gas (N2) balance

[0142]

[0143] ΔEO represents the difference in ethylene oxide concentration between the outlet gas and the inlet gas. The average of three or more sets of test data is taken as the test result for that day.

[0144] After the reaction stabilized, both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 4.

[0145] Table 4

[0146]

[0147]

[0148] As can be seen from the table, the synthesized catalyst, when used in the reaction to prepare ethylene oxide, produces an ethylene oxide selectivity of over 80%.

[0149] Application Example 2

[0150] Catalyst 1 prepared using the catalysts in Tables 1-3 # An oxidation reaction was carried out to prepare low-carbon oxygen-containing compounds (ethylene oxide). After the reaction parameters were varied and the reaction stabilized, both the reactants and products were analyzed using online gas chromatography. The results are shown in Table 5.

[0151] Table 5

[0152]

[0153] The table shows that space velocity has a significant impact on the reaction results.

[0154] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A catalyst for the preparation of ethylene oxide, characterized in that, The catalyst includes a support, a main catalyst, and a co-catalyst; The carrier is Ta3C2; The main catalyst is elemental Ag. The co-catalyst is Ta2O5; The main catalyst accounts for 10-50 wt% of the total mass of the catalyst. The co-catalyst accounts for 5-10 wt% of the mass of the catalyst. The remainder are the aforementioned carriers; The method for preparing the catalyst includes the following steps: (1) Mix the raw materials containing Ta3C2 and the oxidant to undergo a hydrothermal reaction to obtain Ta2O5 / Ta3C2; (2) The Ta2O5 / Ta3C2 obtained in (1) is immersed in silver ammonia solution, left to stand, and calcined to obtain the catalyst.

2. The catalyst according to claim 1, characterized in that, In (1), The oxidant is selected from sodium tetrafluoroborate; The mass ratio of Ta3C2 to the oxidant is 1:(0.5~1); The mixing is performed in a hydrochloric acid solution; The concentration of the hydrochloric acid solution is 0.1M to 1M; The solid-liquid ratio of the raw material containing Ta3C2 and oxidant to the hydrochloric acid solution is 1:(40~70)g / ml.

3. The catalyst according to claim 1, characterized in that, In (1), The temperature of the hydrothermal reaction is 100~140℃; The hydrothermal reaction takes 2 to 8 hours.

4. The catalyst according to claim 1, characterized in that, In (1), The Ta2O5 / Ta3C2 is dried (I); The temperature of the drying process I is 60~100℃; The drying time for step I is 12-36 hours.

5. The catalyst according to claim 1, characterized in that, (2) The impregnation is a vacuum impregnation, and the vacuum degree of the impregnation is 5~15mmHg; The calcination temperature I is 100~200℃; The calcination time is 2 to 60 minutes.

6. The catalyst according to claim 1, characterized in that, (2) The settling time is 30-60 minutes; The solid-liquid ratio of Ta2O5 / Ta3C2 to the silver ammonia solution is 1:(40~100) g / ml.

7. The catalyst according to claim 1, characterized in that, (2) The concentration of silver ions in the silver ammonia solution is 2~5 M.

8. The catalyst according to claim 1, characterized in that, (2) The catalyst is also dried before calcination I; The temperature of the drying II process is 100~120℃; The drying time for step II is 8-12 hours.

9. A method for preparing ethylene oxide, characterized in that, Includes the following steps: A material containing oxygen and ethylene is introduced into the reactor, where it comes into contact with the catalyst and reacts to obtain a product containing ethylene oxide. Wherein, the catalyst is the catalyst according to any one of claims 1 to 8; The volume hourly space velocity of the material is 2500~5000 h⁻¹. -1 ; The molar ratio of oxygen to ethylene is 1:10~15; The reaction temperature is 230~270℃.

10. The preparation method according to claim 9, characterized in that, The reaction time is 3-6 hours; The reaction is carried out at a pressure of 1-3 MPa.

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