A method for producing ethylene by dehydrating ethanol using bimetallic synergistic catalysis

Abstract

The present invention discloses a method for producing ethylene by dehydrating ethanol using bimetallic catalysts. The method produces ethylene by dissolving an alcohol-soluble divalent copper salt and an alcohol-soluble trivalent iron salt in ethanol and conducting a catalytic reaction under light. The method features good catalyst stability, a simple and easy-to-operate preparation process, a fast reaction rate, and low production costs, and has great industrial potential.

Description

Technical Field

[0001] The invention belongs to the technical field of ethylene preparation, and particularly relates to a method for preparing ethylene by dehydrating ethanol using bimetallic synergistic catalysis. Background Art

[0002] It is very important to convert renewable biomass ethanol into high-value industrial chemicals. Ethylene is one of the world's largest chemical products. It is an important raw material for the manufacture of vinyl chloride, styrene, ethylene oxide, acetic acid, etc., and a basic chemical raw material for synthetic fibers, synthetic rubber, and synthetic plastics. It is also the core of the petrochemical industry. In addition, ethylene also promotes organ shedding and aging, and plays an important role in the shedding of flowers, leaves, and fruits. In industry, ethylene is mainly produced by petrochemical cracking, mainly through direct distillation of crude oil products and secondary processing of distillate oils. The above methods have the disadvantages of very complex operating control systems, large temperature spans, harsh operating conditions, and high requirements for process and equipment design and manufacturing. Therefore, it is very important to explore a simple and convenient method to achieve the preparation of ethylene.

[0003] There are many reports on the dehydration of ethanol to produce ethylene. Existing technologies have been developed through thermal catalysis (phosphorus oxide, molecular sieves and mixed acid catalysts, etc.) and photocatalysis (WO 3-x Nanowires, etc.); however, thermal catalysis (phosphorus oxide, molecular sieves and mixed acid catalysts, etc.) usually requires strict conditions, such as high pressure and high temperature; photocatalysis (WO 3-x Nanowires, etc.) involve complex synthesis and regulation processes or the use of precious metals, which limits their economic benefits and large-scale production. Chinese patent CN113105300A discloses a homogeneous ethanol dehydration method for ethylene production. This patented technology requires that ethanol be dehydrated in an inert atmosphere. The continuous reaction requires constant air or oxygen inflow, and the catalyst recycling requires a long recovery time, resulting in a relatively slow reaction rate and low selectivity in an air atmosphere.

[0004] In summary, the existing methods have the disadvantages of strict reaction conditions, complex operation procedures, low economic benefits, slow reaction rates, etc. Therefore, the present invention provides a method with a simple preparation process, easy operation, fast reaction rate, high product selectivity, good stability, and industrial prospects. Summary of the Invention

[0005] To solve the above problems, the purpose of the present invention is to provide a method for realizing bimetallic synergistic catalytic dehydration of ethanol to ethylene by providing a catalyst with good stability, simple and easy preparation process, fast reaction rate, low production cost and good stability.

[0006] Specifically, the present invention provides a method for producing ethylene by dehydrating ethanol using a bimetallic synergistic catalysis;

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A method for producing ethylene by dehydrating ethanol using bimetallic synergistic catalysis comprises the following steps:

[0009] Alcohol-soluble divalent copper salt and alcohol-soluble trivalent iron salt are dissolved in ethanol and catalytically reacted under light to produce ethylene.

[0010] Preferably, the alcohol-soluble divalent copper salt is copper chloride;

[0011] Preferably, the alcohol-soluble trivalent iron salt is ferric chloride;

[0012] Copper chloride and ferric chloride were purchased commercially and used directly without post-treatment.

[0013] Preferably, the total concentration of metal ions in the alcohol-soluble divalent copper salt and the alcohol-soluble trivalent iron salt is 1 to 100 mM.

[0014] Further preferably, the total concentration of metal ions in the alcohol-soluble divalent copper salt and the alcohol-soluble trivalent iron salt is 10 mM.

[0015] Preferably, the molar ratio of copper ions in the alcohol-soluble divalent copper salt to iron ions in the alcohol-soluble trivalent iron salt is 7:1-1:3.

[0016] Further preferably, the molar ratio of copper ions in the alcohol-soluble divalent copper salt to iron ions in the alcohol-soluble trivalent iron salt is 3:1.

[0017] Preferably, the ethanol is anhydrous ethanol.

[0018] Preferably, the solution before the catalytic reaction is a yellow-green transparent solution.

[0019] Preferably, the catalytic reaction is carried out in a closed environment.

[0020] More preferably, the sealed environment is a sealed environment of air atmosphere or a sealed environment of inert atmosphere, preferably a sealed environment of air atmosphere.

[0021] More preferably, the volume ratio of ethanol to air is 4:10-200, preferably 4:50.

[0022] Preferably, the temperature of the catalytic reaction is room temperature; room temperature is 20-30°C.

[0023] Preferably, the catalytic reaction time is 1 h-2 h.

[0024] More preferably, the catalytic reaction time is 1 h.

[0025] Preferably, the wavelength range of the light includes any wavelength between 300 nm and 450 nm.

[0026] Further preferably, the wavelength range of the light includes any wavelength from 300 nm to 365 nm.

[0027] Further preferably, the illumination is a xenon lamp with a filter, wherein the filter is an AM1.5G filter; the light intensity of the xenon lamp is 100-200 mW cm -2 .

[0028] More preferably, the light intensity of the xenon lamp is 150 mW cm -2 .

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The method for preparing ethylene by bimetallic synergistic catalysis of the present invention has a fast reaction rate and high yield.

[0031] (2) Both metal catalysts of the present invention are cheap and easy to obtain, the reaction conditions are mild, and the reaction apparatus is simple.

[0032] (3) The method of producing ethylene by bimetallic synergistic catalysis of the present invention can be carried out in an air atmosphere, has strong selectivity, can react continuously, and has great industrial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Graph showing the content of reaction gas products detected by gas chromatography in Examples 3 and 7;

[0034] Figure 2 The curves of the reaction gas products detected by gas chromatography over time in Examples 7 and 8 are as follows;

[0035] Figure 3 This is a graph showing changes in the ultraviolet absorption of the solution in Example 9;

[0036] Figure 4 This is a graph showing the content of the gas product stability test in Example 10;

[0037] Figure 5 Figure 1-10 of the reaction apparatus;

[0038] Figure 6 The curves showing the change of reaction gas products over time using gas chromatography in Examples 3 and 11;

[0039] Figure 7 This is a diagram of the reaction apparatus in Example 11. DETAILED DESCRIPTION

[0040] The following examples clearly and completely describe the technical solutions of the present invention. Obviously, the described implementation examples are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without inventive work are within the scope of protection of the present invention.

[0041] Example 1

[0042] 40 μmol of commercially available CuCl₂ was placed in a 50 mL quartz vial for photocatalytic reaction. 4 mL of anhydrous ethanol was added until completely dissolved, yielding a green, transparent solution. The sealed vial was placed over a xenon lamp fitted with an AM1.5 G filter and the lamp was turned on to initiate the photocatalytic reaction. After one hour of reaction, the gaseous products were detected by gas chromatography. The experimental results are shown in Table 1.

[0043] Example 2

[0044] 35 μmol and 5 μmol of commercially available CuCl₂ and FeCl₃ (CuCl₂:FeCl₃ = 7:1), respectively, were placed in a 50 mL quartz vial for photocatalytic reaction. 4 mL of anhydrous ethanol was added until completely dissolved, yielding a yellow-green transparent solution. The sealed reaction vial was placed over a xenon lamp fitted with an AM1.5 G filter and the lamp was turned on to initiate the photocatalytic reaction. After 1 hour of reaction, gaseous products were detected by gas chromatography. The experimental results are shown in Table 1.

[0045] Example 3

[0046] 30 μmol and 10 μmol of commercially available CuCl₂ and FeCl₃ (CuCl₂:FeCl₃ = 3:1), respectively, were placed in a 50 mL quartz vial for photocatalytic reaction. 4 mL of anhydrous ethanol was added until completely dissolved, yielding a yellow-green transparent solution. The sealed vial was placed over a xenon lamp fitted with an AM1.5 G filter, and the lamp was turned on to initiate the photocatalytic reaction. Gas products were detected by gas chromatography at intervals and again after 1 hour of reaction. The experimental results are shown in Table 1.

[0047] Example 4

[0048] 20 μmol and 20 μmol of commercially available CuCl₂ and FeCl₃ (CuCl₂:FeCl₃ = 1:1), respectively, were placed in a 50 mL quartz vial for photocatalytic reaction. 4 mL of anhydrous ethanol was added until completely dissolved, yielding a yellow-green transparent solution. The sealed reaction vial was placed over a xenon lamp fitted with an AM1.5 G filter and the lamp was turned on to initiate the photocatalytic reaction. After 1 hour of reaction, gaseous products were detected by gas chromatography. The experimental results are shown in Table 1.

[0049] Example 5

[0050] 10 μmol and 30 μmol of commercially available CuCl₂ and FeCl₃ (CuCl₂:FeCl₃ = 1:3), respectively, were placed in a 50 mL quartz vial for photocatalytic reaction. 4 mL of anhydrous ethanol was added until completely dissolved, yielding a yellow-green transparent solution. The sealed vial was placed over a xenon lamp fitted with an AM1.5 G filter and the lamp was turned on to initiate the photocatalytic reaction. After 1 hour of reaction, gaseous products were detected by gas chromatography. The experimental results are shown in Table 1.

[0051] Example 6

[0052] 40 μmol of commercial FeCl₃ was placed in a 50 mL quartz vial for photocatalytic reaction. 4 mL of anhydrous ethanol was added until completely dissolved, yielding a yellowish-brown transparent solution. The sealed vial was placed over a xenon lamp fitted with an AM1.5 G filter and the lamp was turned on to initiate the photocatalytic reaction. After one hour of reaction, the gaseous products were detected by gas chromatography. The experimental results are shown in Table 1.

[0053] Table 1 shows the types, contents and ethylene selectivity of the reaction gas products detected by gas chromatography at different molar ratios of the bimetallic catalysts in Examples 1-6.

[0054] Table 1

[0055]

[0056] From the results in Table 1, the results of Examples 1-6 show that when the molar ratio of the bimetallic catalyst is 3:1 (CuCl2:FeCl3=3:1), the yield of the gas product ethylene is the highest and the selectivity is the best, which can reach 98.29%; the results of Examples 1, 3, and 6 show that the bimetallic catalyst has a 50-fold and 4-fold increase in the yield of the gas product ethylene compared to CuCl2 and FeCl3 alone, respectively. Therefore, the performance of the bimetallic catalyst is significantly better than that of CuCl2 and FeCl3 alone.

[0057] Example 7

[0058] Take 30μmol and 10μmol of commercial CuCl2 and FeCl3 (CuCl2:FeCl3=3:1) respectively, put them into a 50mL quartz bottle for photocatalytic reaction, add 4mL of anhydrous ethanol, and make it completely dissolved to obtain a yellow-green transparent solution. Pass nitrogen gas to make it an inert atmosphere. Place the sealed reaction bottle on top of a xenon lamp with an AM1.5G filter, turn on the xenon lamp to start the photocatalytic reaction. Use gas chromatography to detect gas products at intervals; after 1h of reaction, use gas chromatography to detect gas products again. The experimental results are as follows Figure 1 shown.

[0059] Figure 1The figures are for detecting the content of reaction gas products by gas chromatography in Examples 3 and 7; it shows that compared with the inert atmosphere, the gas product ethylene yield in the air atmosphere is greater, the rate is faster, and the catalytic performance is better.

[0060] Example 8

[0061] Take 40 μmol of commercial CuCl2 and put it into a 50 mL quartz bottle for photocatalytic reaction. Add 4 mL of anhydrous ethanol and dissolve it completely to obtain a green transparent solution. Pass nitrogen gas to make it an inert atmosphere. Place the sealed reaction bottle on top of a xenon lamp with an AM1.5 G filter, turn on the xenon lamp to start the photocatalytic reaction. Use gas chromatography to detect gas products at intervals; after 1 hour of reaction, use gas chromatography to detect gas products again. The experimental results are as follows Figure 2 shown.

[0062] Figure 2 The curves of the reaction gas products changing with time detected by gas chromatography for Examples 7 and 8 illustrate that the bimetallic catalyst has a faster reaction rate and a larger yield compared with CuCl2 alone.

[0063] Example 9

[0064] Take 30μmol and 10μmol of commercial CuCl2 and FeCl3 (CuCl2:FeCl3=3:1) respectively, place them in a 50mL quartz bottle for photocatalytic reaction, add 4mL of anhydrous ethanol to completely dissolve them to obtain a yellow-green transparent solution, and measure the absorption using a UV spectrophotometer before the reaction; place the sealed reaction bottle on top of a xenon lamp with an AM1.5G filter, turn on the xenon lamp to start the photocatalytic reaction. As the reaction proceeds, the color of the solution gradually fades. After 1 hour of reaction, the absorption is measured again using a UV spectrophotometer. The measurement results are as follows: Figure 3 shown.

[0065] Figure 3 The figure shows the change of ultraviolet absorption of the solution before and after the reaction in Example 9. Compared with that before the reaction, the ultraviolet absorption curve after 1 hour of reaction is blue-shifted, but the ultraviolet absorption edge of the solution is still greater than 400nm, indicating that the catalytic activity is still maintained after 1 hour of reaction.

[0066] Example 10

[0067] Take 30μmol and 10μmol of commercial CuCl2 and FeCl3 (CuCl2:FeCl3=3:1) respectively, put them into a 50mL quartz bottle for photocatalytic reaction, add 4mL of anhydrous ethanol to completely dissolve them to obtain a yellow-green transparent solution. Place the sealed reaction bottle on top of a xenon lamp with an AM1.5 G filter, turn on the xenon lamp to start the photocatalytic reaction. After 1 hour of reaction, the gas products are detected by gas chromatography. As the reaction proceeds, the color of the solution becomes lighter. After nitrogen is introduced to discharge the gas products in the quartz bottle, the bottle cap is opened and placed in the air for 1 hour to fill the bottle with air. Use this solution to carry out the above photocatalytic reaction again, and use gas chromatography to detect the gas products. Repeat the above reaction 4 times. The reaction results are as follows Figure 4 shown.

[0068] Figure 4 This is a graph showing the content of the gas product stability test using gas chromatography in Example 10. Figure 5 This is a physical picture of the reaction device used in Examples 1-10; the results show that the bimetallic catalyst has good stability; after four cycles of reaction, the ethylene content remains at 76.2% of the original.

[0069] The above catalytic reaction results demonstrate a rapid reaction rate for the gaseous product ethylene, reaching 0.42 mol / mol per hour (as shown in Example 3 in Table 1), a selectivity for the gaseous product ethylene of 98.2%, and good stability. The "mol" in "mol / mol" refers to the molar mass of the product ethylene and the total molar mass of the catalysts (copper chloride and ferric chloride), respectively.

[0070] Example 11

[0071] Amplification experiment (scale up): Take 120μmol and 40μmol of commercial CuCl2 and FeCl3 (CuCl2:FeCl3=3:1) respectively, put them into a 200mL photocatalytic reaction reactor, add 16mL of anhydrous ethanol, and dissolve them completely to obtain a yellow-green transparent solution. Place the sealed reactor under a xenon lamp with an AM1.5G filter, turn on the xenon lamp to start the reaction. Use gas chromatography to detect gas products at intervals; after 1h of reaction, use gas chromatography to detect gas products again. The reaction results are as follows: Figure 6 shown.

[0072] Figure 6 The curves of the reaction gas products detected by gas chromatography over time for Examples 3 and 11 are as follows: Figure 7 This is a physical picture of the reactor used in Example 11.

[0073] The above results show that the catalytic performance of the bimetallic catalyst can be fully maintained after proportional amplification, indicating that the method for preparing ethylene of the present invention is easy to scale up and has great industrial application prospects.

[0074] The above results show that the catalyst of this method has good stability, a simple and easy preparation process, a fast reaction rate, and low production cost, and has great industrial application prospects.

[0075] The above description fully discloses the specific embodiments of the present invention. It should be noted that any changes or modifications made to the specific embodiments of the present invention by any person skilled in the art without departing from the scope of the claims of the present invention are equivalent to equivalent implementation examples. Accordingly, the scope of the claims of the present invention is not limited to the aforementioned specific embodiments.

Claims

1. A method for producing ethylene by dehydrating ethanol using bimetallic synergistic catalysis, characterized in that: The following steps are involved: An alcohol-soluble divalent copper salt and an alcohol-soluble trivalent iron salt are dissolved in ethanol and subjected to a catalytic reaction under light to obtain ethylene; the alcohol-soluble divalent copper salt is copper chloride; the alcohol-soluble trivalent iron salt is ferric chloride; The total concentration of metal ions in the alcohol-soluble divalent copper salt and the alcohol-soluble ferric salt is 1-100 mM; the catalytic reaction is carried out in a closed environment; the closed environment is a closed environment with an air atmosphere or a closed environment with an inert atmosphere; the wavelength range of the illumination is any wavelength of 300-450 nm; and the molar ratio of copper ions in the alcohol-soluble divalent copper salt to iron ions in the alcohol-soluble ferric salt is 7:1-1:

3.

2. The method for producing ethylene by dehydration of ethanol using bimetallic synergistic catalysis according to claim 1, characterized in that: The ethanol is anhydrous ethanol.

3. The method for producing ethylene by dehydration of ethanol using bimetallic synergistic catalysis according to claim 1, characterized in that: The volume ratio of the ethanol to the air is 4:10-200.

4. The method for producing ethylene by dehydration of ethanol using bimetallic synergistic catalysis according to claim 1, characterized in that: The temperature of the catalytic reaction is room temperature; the time of the catalytic reaction is 1 h to 2 h.

5. The method for producing ethylene by dehydration of ethanol using bimetallic synergistic catalysis according to claim 1, characterized in that: The illumination is a xenon lamp with a filter, wherein the filter is an AM1.5G filter; the light intensity of the xenon lamp is 100-200mW cm -2 .

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