Preparation method of metal ZIF-derived (GaCe) Ox catalyst and method for preparing propylene by catalyzing dehydrogenation of CO2 propane oxide
By combining Ga and Ce in the catalyst, metal ZIF-derived (GaCe)Ox catalyst was prepared, and the reaction conditions were optimized through CO2-ODHP reaction, which solved the problems of rapid catalyst deactivation and low CO2 utilization efficiency, achieving high efficiency and environmental protection production of propylene.
Patent Information
- Application Number
- CN202411442083.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2025-02-14
AI Technical Summary
In the production process of propylene, existing catalysts are prone to rapid inactivation due to side reactions such as thermal cracking, and the utilization efficiency of CO2 is low, resulting in poor environmental protection and economic benefits.
Using a metal ZIF-derived (GaCe)Ox catalyst, a catalyst with high reactivity and excellent catalytic properties was prepared by organically combining Ga and Ce, and the reaction conditions were optimized through CO2-ODHP reaction.
It significantly improves the selectivity and catalytic activity of propylene, extends the life of the catalyst, improves the utilization rate of CO2, reduces the deposition of coke, and has good environmental protection and economic benefits.
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Abstract
Description
Technical Field
[0001] The invention relates to a catalyst, in particular to a method for preparing a metal ZIF-derived (GaCe)Ox catalyst. The invention also relates to the catalytic application of the (GaCe)Ox catalyst, and belongs to the technical field of thermal catalytic materials. Background Art
[0002] Propylene is an important component of the petrochemical industry and one of the important raw materials for downstream chemical products. It has broad practical prospects and huge economic benefits. With the continuous growth of market demand, the gap between industrial production and existing demand is getting bigger and bigger. Coupled with the large amount of cheap alkane raw materials from shale gas and other sources, the direct production of propylene (PDH) from propane can achieve the economical production of more expensive olefins from low-cost saturated alkanes. However, this reaction is endothermic and needs to be carried out under high temperature and low pressure conditions. Such harsh reaction conditions promote the occurrence of side reactions such as thermal cracking. The light alkanes and coke produced will cause the catalyst to deactivate rapidly. By introducing CO2 as a mild oxidant for the CO2-ODHP reaction, on the one hand, the hydrogen produced can be consumed by the reverse water gas reaction (CO2+H2→CO+H2O), and the equilibrium can be transferred to the product. On the other hand, the deposition of coke is inhibited, and the reverse Boudouard reaction occurs, avoiding rapid deactivation due to the formation of coke (CO2+C→2CO). At the same time, the reaction slows down the emission of greenhouse gases for the utilization of CO2, which has far-reaching significance in terms of environmental protection and economy.
[0003] The presence of CO2 can significantly promote the dehydrogenation of alkanes on Ga2O3 or supported Ga2O3 catalysts. The high reactivity of β-Ga2O3 and the rich coordination unsaturated Ga 3+ (Ⅳ) and the conjugation effect of H and O, but the low specific surface area limits its catalytic performance. Mesoporous β-Ga2O3 materials, due to the good structural characteristics and increased surface area of mesoporous materials, form a large number of coordinated unsaturated Ga sites, thus obtaining good catalytic performance. CeO2 as a carrier can improve the utilization rate of CO2. Summary of the invention
[0004] In order to better utilize CO2 and improve the activity of propane dehydrogenation to propylene, the two metals Ga and Ce are organically combined to provide a preparation method of a metal ZIF-derived (GaCe)Ox catalyst and its application in CO2 oxidation propane dehydrogenation to propylene In order to achieve the above objectives, the first technical solution provided by the present invention is as follows: (1) Place 11 mmol of Ga(NO3)3·6H2O and 11 mmol of Ce(NO3)3·6H2O in 22 mL of 75% ethanol solution and sonicate for 10 min to completely dissolve them. (2) Place 2.5 g of 2-methylimidazole in a 75% ethanol solution and sonicate for 10 min to completely dissolve it; (3) Mix the two solutions in (1) together and sonicate for 30 min to make them evenly dispersed; (4) Add the solution in (3) to (2) at a rate of 2 drops / s. After the addition is complete, perform ultrasonic cavitation at room temperature for 30 min and then stir for 1 h to obtain a suspension. (5) Place the suspension in (4) in a 100 mL polytetrafluoroethylene liner and perform a hydrothermal reaction at 140 °C for 12 h. (6) The product after the reaction in (5) is cooled and centrifuged, washed three times with water and ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 h; (7) The dried product in (6) was placed in a muffle furnace and calcined at 600 °C for 12 h.
[0005] The second technical solution provided by the present invention is to use the (GaCe)Ox catalyst prepared by the above method for CO2 oxidation of propane to produce propylene. The catalytic conditions are as follows: (1) The amount of catalyst used is 2 g; (2) The catalyst is tableted and sieved using an infrared tablet press to obtain a granular catalyst, and the sieving condition is a particle size of 0.3 mm to 0.45 mm; (3) The composition of the reaction gas is 2.5% propane, 5% CO2 and 97.5% N2; (4) The flow rate of the reaction gas is 20 mL / min (5) The gas used for temperature protection is N2, with a flow rate of 20 mL / min; (6) The reaction temperature is 350-550 ℃ The (GaCe)Ox catalyst provided by the present invention is applied to the field of catalysis of CO2 propane oxidative dehydrogenation to produce propylene.
[0006] Compared with the prior art, the technical solution provided by the present invention has the following technical advantages: (1) No precious metals are used in the preparation process, which greatly reduces the cost price; (2) Using Ga2O3 as the active site, the selectivity of propylene was greatly improved in the process of catalytic propane oxidative dehydrogenation; (3) CeO2 as a carrier can improve the utilization rate of CO2.
[0007] Figure 1 The catalytic activity of catalysts with different Ga ion contents at different temperatures; Figure 2 CO2 utilization rate of catalysts with different Ga ion contents at different temperatures; Figure 3 This is the scanning electron microscope (SEM) image of the (GaCe)Ox (Ga:Ce=12:1) catalyst. DETAILED DESCRIPTION
[0008] The technical solution of the present invention will be described in detail below through specific embodiments, but it should be clearly stated that these embodiments are for illustration and are not to be construed as limiting the scope of the present invention.
[0009] Example 1: This example provides a method for preparing a metal ZIF-derived (GaCe)Ox catalyst for thermal catalytic CO2 propane oxidative dehydrogenation to propylene catalyst, which is prepared by the following method: (1) Place 2.813 g of Ga(NO3)3·6H2O and 4.776 g of Ce(NO3)3·6H2O in 22 mL of 75% ethanol solution and sonicate for 10 min to completely dissolve them. (2) Place 2.5 g of 2-methylimidazole in a 75% ethanol solution and sonicate for 10 min to completely dissolve it; (3) Mix the two solutions in (1) together and sonicate for 30 min to make them evenly dispersed; (4) Add the solution in (3) to (2) at a rate of 2 drops / s. After the addition is complete, perform ultrasonic cavitation at room temperature for 30 min and then stir for 1 h to obtain a suspension. (5) Place the suspension in (4) in a 100 mL polytetrafluoroethylene liner and perform a hydrothermal reaction at 140 °C for 12 h. (6) The product after the reaction in (5) is cooled and centrifuged, washed three times with water and ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 h; (7) The dried product in (6) was placed in a muffle furnace and calcined at 600 °C for 12 h.
[0010] Example 2: This example provides a method for preparing a metal ZIF-derived (GaCe)Ox catalyst for thermal catalytic CO2 propane oxidative dehydrogenation to propylene catalyst, which is prepared by the following method: (1) Place 5.19 g of Ga(NO3)3·6H2O and 1.466 g of Ce(NO3)3·6H2O in 22 mL of 75% ethanol solution and sonicate for 10 min to completely dissolve them. (2) Place 2.5 g of 2-methylimidazole in a 75% ethanol solution and sonicate for 10 min to completely dissolve it; (3) Mix the two solutions in (1) together and sonicate for 30 min to make them evenly dispersed; (4) Add the solution in (3) to (2) at a rate of 2 drops / s. After the addition is complete, perform ultrasonic cavitation at room temperature for 30 min and then stir for 1 h to obtain a suspension. (5) Place the suspension in (4) in a 100 mL polytetrafluoroethylene liner and perform a hydrothermal reaction at 140 °C for 12 h. (6) The product after the reaction in (5) is cooled and centrifuged, washed three times with water and ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 h; (7) The dried product in (6) was placed in a muffle furnace and calcined at 600 °C for 12 h.
[0011] Example 3: This example provides a method for preparing a metal ZIF-derived (GaCe)Ox catalyst for thermal catalytic CO2 propane oxidative dehydrogenation to propylene catalyst, which is prepared by the following method: (1) Place 2.813 g of Ga(NO3)3·6H2O and 2.388 g of Ce(NO3)3·6H2O in 22 mL of 75% ethanol solution and sonicate for 10 min to completely dissolve them. (2) Place 2.5 g of 2-methylimidazole in a 75% ethanol solution and sonicate for 10 min to completely dissolve it; (3) Mix the two solutions in (1) together and sonicate for 30 min to make them evenly dispersed; (4) Add the solution in (3) to (2) at a rate of 2 drops / s. After the addition is complete, perform ultrasonic cavitation at room temperature for 30 min and then stir for 1 h to obtain a suspension. (5) Place the suspension in (4) in a 100 mL polytetrafluoroethylene liner and perform a hydrothermal reaction at 140 °C for 12 h. (6) The product after the reaction in (5) is cooled and centrifuged, washed three times with water and ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 h; (7) The dried product in (6) was placed in a muffle furnace and calcined at 600 °C for 12 h.
[0012] Example 4: This example provides a method for preparing a metal ZIF-derived (GaCe)Ox catalyst for thermal catalytic CO2 propane oxidative dehydrogenation to propylene catalyst, which is prepared by the following method: (1) Place 2.813 g of Ga(NO3)3·6H2O and 1.194 g of Ce(NO3)3·6H2O in 22 mL of 75% ethanol solution and sonicate for 10 min to completely dissolve them. (2) Place 2.5 g of 2-methylimidazole in a 75% ethanol solution and sonicate for 10 min to completely dissolve it; (3) Mix the two solutions in (1) together and sonicate for 30 min to make them evenly dispersed; (4) Add the solution in (3) to (2) at a rate of 2 drops / s. After the addition is complete, perform ultrasonic cavitation at room temperature for 30 min and then stir for 1 h to obtain a suspension. (5) Place the suspension in (4) in a 100 mL polytetrafluoroethylene liner and perform a hydrothermal reaction at 140 °C for 12 h. (6) The product after the reaction in (5) is cooled and centrifuged, washed three times with water and ethanol respectively, and dried in a vacuum drying oven at 60 °C for 12 h; (7) The dried product in (6) was placed in a muffle furnace and calcined at 600 °C for 12 h.
[0013] according to Figure 1 Figure 2 The catalytic activity of GaCe bimetallic oxide is better than that of single metal catalytic activity. When Ga:Ce=12:1, there is interaction between the metal active components and the catalytic activity reaches the best effect.
[0014] The above are only preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.
Claims
1. A method for preparing a metal ZIF-derived (GaCe)Ox catalyst, characterized in that: The bimetallic ZIF precursor is calcined at high temperature in air, and the obtained material is used for CO2 oxidation of propane dehydrogenation to propylene, and different catalytic effects are obtained by adjusting the metal ratio, including the following steps: A certain amount of Ga(NO3)3·6H2O and Ce(NO3)3·6H2O were placed in 22 mL of 75% ethanol solution and completely dissolved by ultrasound; Place 2-methylimidazole in a 75% ethanol solution and dissolve it completely by ultrasonication; The two solutions in (1) are mixed together and ultrasonicated to make them dispersed evenly; The solution in (3) is added dropwise to (2). After the addition is complete, ultrasonic cavitation is performed at room temperature for a period of time, and then stirring is performed to obtain a suspension. Place the suspension in (4) in a 100 mL polytetrafluoroethylene liner for hydrothermal reaction, controlling the hydrothermal temperature and time. The product after the reaction in (5) is cooled and centrifuged, washed three times with water and ethanol respectively, and dried in a vacuum drying oven, controlling the drying temperature and time; The dried product in (6) is placed in a muffle furnace and calcined, and the calcination temperature and time are controlled; Grind the material in (7) and press it into tablets and sieve it to obtain granular material. Take a certain amount of material in (8) and put it in a quartz tube, pad it with quartz wool, pass N2 to raise the temperature to the target temperature, then pass the reaction gas to react. After a period of reaction, measure the gas content at the outlet.
2. The method for preparing the metal ZIF-derived (GaCe)Ox catalyst according to claim 1, characterized in that: In step (1), the ratio of Ga to Ce is (16:1, 12:1, 8:1, 6:1, 4:1, 3:1, 2:1, 1.5:1, 1:1, 1:2, 1:4, 1:8), and the total amount of metal is 22 mmol.
3. The method for preparing the metal ZIF-derived (GaCe)Ox catalyst according to claim 1, characterized in that: The ultrasonic time in steps (1) and (2) is 10 min, the ultrasonic time in step (3) is 30 min, and the ultrasonic time in step (4) is 30 min.
4. The method for preparing the metal ZIF-derived (GaCe)Ox catalyst according to claim 1, characterized in that: The stirring time in step (4) is 1 h.
5. The method for preparing the metal ZIF-derived (GaCe)Ox catalyst according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (5) is 140 °C and the time is 12 h.
6. The method for preparing the metal ZIF-derived (GaCe)Ox catalyst according to claim 1, characterized in that: In step (6), the drying temperature is 60°C and the drying time is 12 h.
7. The method for preparing the metal ZIF-derived (GaCe)Ox catalyst according to claim 1, characterized in that: In step (7), the calcination temperature is 600°C and the calcination time is 4 h.
8. A method for preparing a metal ZIF-derived (GaCe)Ox catalyst, characterized in that: The method is prepared by the method described in claims 1 to 7.
9. The method of preparing propylene by oxidizing propane with CO2 and dehydrogenating propane using the catalyst according to claim 8, characterized in that The amount of catalyst used is 2 g, the content of the reaction gas is 2.5% propane plus 5% CO2, the remaining gas is N2, the flow rate of the reaction gas is 20 mL / min, and the reaction temperature is 350-550 ℃.