Fluorination method of fluorination catalyst precursor
Through the processes of low-temperature purge, pressurized low-temperature fluorination, heating-increasing ratio fluorination and purge cooling, the fluorination process of fluorinated catalyst precursors is optimized, and the problems of low catalyst conversion rate and short service life in traditional methods are solved. Achieve higher conversion rates and longer service life.
Patent Information
- Application Number
- CN202411244850.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-06
- Publication Date
- 2024-12-20
AI Technical Summary
The fluorination method of traditional fluorination catalyst precursors has low catalyst conversion rate and the catalyst is damaged, resulting in a shorter service life.
The four steps of low-temperature purge, pressurized low-temperature fluorination, heating-increasing ratio fluorination and purge cooling are adopted. By adjusting the ratio and pressure of nitrogen and hydrogen fluoride gas, the reaction temperature and pressure are controlled, and the fluorination process is optimized.
It significantly improves the conversion rate and production quality of the catalyst and extends the service life of the catalyst.
Smart Images
Figure BDA0005030358160000051
Abstract
Description
Technical Field
[0001] The invention relates to a fluorination method for a fluorination catalyst precursor used in a fluoroalkane preparation process, and in particular to a fluorination method for a fluorination catalyst precursor. Background Art
[0002] As we all know, 1,1,1,2-tetrafluoroethane (HFC-134a) and pentafluoroethane (HFC-125) are ODS (ozone depleting substances) substitutes and are new green and environmentally friendly refrigerants. Chinese invention patent ZL01141970.9 discloses a fluorination catalyst that can be used for the preparation of 1,1,1,2-tetrafluoroethane. The fluorination catalyst has the structural formula of Crx 0.005-0.5Y 0.005-0.300.1-1,0F 1.0-3.0', where X is Mn, Co or Zn, and Y is Mg or Ni. The catalyst has the advantages of high activity, good stability, and long service life. However, the catalyst precursor cannot be used directly in production, and the catalyst precursor must be fluorinated before it can be used in production. The traditional catalyst precursor fluorination method raises the temperature of the catalyst precursor fixed bed to 200°C, and introduces a certain amount of N2 and HF mixed gas to perform temperature-variable fluorination to 350°C, and then performs pressure-variable fluorination, that is, the catalyst precursor fixed bed pressure is raised to 0.3Mpa. The fluorination result of the catalyst precursor by this method is not ideal, and the catalyst conversion rate is 25-30%. In addition, the catalyst precursor is damaged during the fluorination process, and its hardness decreases, which greatly shortens the service life of the catalyst.
[0003] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention
[0004] In order to solve the above technical problems, the present invention proposes a fluorination method for a fluorination catalyst precursor, so as to achieve the purpose of improving the conversion rate of the catalyst, improving the production quality of the catalyst precursor and extending the service life of the catalyst.
[0005] To achieve the above object, the technical solution of the present invention is as follows:
[0006] A fluorination method for a fluorination catalyst precursor comprises the following steps:
[0007] (1) Perform a low-temperature purge process;
[0008] (2) Pressurized low-temperature fluorination process;
[0009] (3) Temperature-increasing variable ratio fluorination process;
[0010] (4) Purge and cooling process.
[0011] The present invention provides a new fluorination method for a fluorination catalyst precursor which sequentially undergoes a low-temperature purging process, a pressurized low-temperature fluorination process, a temperature-raising variable ratio fluorination process and a purging and cooling process, thereby achieving the purposes of improving the conversion rate of the catalyst, improving the production quality of the catalyst precursor and extending the service life of the catalyst.
[0012] It is further worth noting that step (1) specifically comprises: adding the fluorination catalyst precursor into a fixed bed reactor, heating to 100-120° C., and continuously introducing N 2 gas to purge the fluorination catalyst precursor;
[0013] After N2 gas has been passed for a period of time, a mixed gas of N2 and HF is continuously introduced.
[0014] It is further worth noting that the contact time between nitrogen and catalyst is 1 to 2 hours, and the space velocity is 60 to 70 L / kg.h; the temperature of the N2 and HF mixed gas is maintained at 100 to 120°C, and the space velocity is 50 to 55 L / kg.h.
[0015] It is further worth noting that during the process of passing the mixed gas of N2 and HF, the concentration of the fluorinated gas tail gas was monitored once every hour;
[0016] In the initial case, N2 and HF are mixed at a ratio of 1:1.5; when it is detected that the ratio of N2 to HF in the exhaust gas reaches 1:1.5, the ratio of the input mixed gas is gradually adjusted to 1:2.5; when the exhaust gas concentration is consistent with the ratio of the introduced gas again, the ratio of the input mixed gas is gradually adjusted to 1:5.
[0017] It is further worth noting that step (2) specifically comprises: increasing the gas pressure in the fixed bed reactor to 0.2 MPa, and after a period of time, further increasing the gas pressure in the fixed bed reactor to 0.3 MPa, and after a period of time, further increasing the gas pressure in the fixed bed reactor to 0.5 MPa.
[0018] It is further worth noting that step (3) is specifically as follows: when the proportion of HF in the fluorinated tail gas reaches the proportion of the N2 and HF mixed gas before introduction, the ratio of the N2 and HF mixed gas is adjusted to 1:1.5, and at the same time, the gas pressure in the fixed bed reactor is adjusted to normal pressure, and the fixed bed reactor is heated to 150°C;
[0019] When the temperature of the fixed bed reactor reaches 150°C, the ratio of N2 to HF mixed gas is adjusted to 1:5;
[0020] When the HF ratio in the fluorinated tail gas reaches the ratio of the N2 and HF mixed gas before introduction, the ratio of the N2 and HF mixed gas is adjusted to 1:1.5 again, and the fixed bed reactor is heated to 200°C;
[0021] The above steps were repeated until the fixed bed reactor was heated to 350°C with 50°C as a node.
[0022] It is further worth noting that the fixed bed reactor has a heating rate of 3 to 5°C / h.
[0023] It is further worth noting that a high-temperature pressurized variable ratio fluorination process is provided after step (3), specifically: after the fixed bed reactor is heated to 350°C, the gas pressure of the fixed bed reactor is increased to 0.5 MPa, and when the HF ratio in the fluorination tail gas reaches the ratio of the N2 and HF mixed gas before introduction, the ratio of the N2 and HF mixed gas (V) is adjusted to 1:10.
[0024] It is further worth noting that step (4) specifically comprises: reducing the gas pressure of the fixed bed reactor to normal pressure, then stopping the mixed gas, and re-introducing N2 gas to purge and cool the catalyst in the fixed bed reactor until the temperature of the catalyst in the fixed bed reactor is reduced to normal temperature, with an air velocity of 60 to 70 L / kg.h.
[0025] The present invention has the following advantages:
[0026] 1. The present invention provides a new fluorination method for a fluorination catalyst precursor which sequentially undergoes a low-temperature purging process, a pressurized low-temperature fluorination process, a temperature-increasing ratio fluorination process and a purging and cooling process, thereby achieving the purpose of improving the conversion rate of the catalyst, improving the production quality of the catalyst precursor and extending the service life of the catalyst. DETAILED DESCRIPTION
[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below.
[0028] The present invention provides a fluorination method for a fluorination catalyst precursor. The working principle is to provide a new fluorination method for a fluorination catalyst precursor which sequentially undergoes a low-temperature purging process, a pressurized low-temperature fluorination process, a temperature-raising variable ratio fluorination process and a purging and cooling process, thereby achieving the purposes of improving the conversion rate of the catalyst, improving the production quality of the catalyst precursor and extending the service life of the catalyst.
[0029] The present invention is further described in detail below with reference to examples and specific implementation modes.
[0030] A fluorination method for a fluorination catalyst precursor comprises the following steps:
[0031] (1) Perform a low-temperature purge process;
[0032] The fluorination catalyst precursor is added into a fixed bed reactor, heated to 100-120°C, and N2 gas is continuously introduced to purge the fluorination catalyst precursor; the contact time between nitrogen and catalyst is 1-2 hours, and the space velocity is 60-70 L / kg.h; then a mixed gas of N2 and HF is introduced, wherein the temperature of the mixed gas of N2 and HF is maintained at 100-120°C, and the space velocity is 50-55 L / kg.h.
[0033] The introduction of N2 and HF mixed gas is as follows:
[0034] In the initial case, N2 and HF in the N2 and HF mixed gas are mixed at a ratio of 1:1.5. During the continuous ventilation process, the exhaust concentration of the fluorinated gas is monitored every hour. When it is monitored that the ratio of N2 to HF in the exhaust gas is consistent with the ratio of the incoming gas, that is, the ratio of N2 to HF reaches 1:1.5, the ratio of the input mixed gas is gradually adjusted to 1:2.5; the exhaust concentration of the fluorinated gas is monitored every hour. When it is monitored that the ratio of N2 to HF in the exhaust gas is consistent with the ratio of the incoming gas, that is, the ratio of N2 to HF reaches 1:2.5, the incoming mixed gas is gradually adjusted to 1:5.
[0035] (2) Pressurized low-temperature fluorination process: the gas pressure in the fixed bed reactor is increased to 0.2 MPa, and after a period of time, the gas pressure in the fixed bed reactor is further increased to 0.3 MPa, and after a period of time, the gas pressure in the fixed bed reactor is further increased to 0.5 MPa.
[0036] (3) Temperature-increasing variable ratio fluorination process;
[0037] When the ratio of N2 to HF in the fluorinated tail gas is consistent with the other gases introduced, that is, when the ratio of N2 to HF reaches 1:5, the ratio of N2 to HF mixed gas is adjusted to 1:1.5, and at the same time, the gas pressure in the fixed bed reactor is adjusted to normal pressure, and the fixed bed reactor is heated to 150°C, and the heating rate of the fixed bed reactor is 3-5°C / h;
[0038] When the temperature of the fixed bed reactor reaches 150°C, the ratio of N2 to HF mixed gas is adjusted to 1:5;
[0039] Then the fluorination tail gas is monitored every two hours. When the ratio of N2 to HF in the fluorination tail gas is consistent with the ratio of the incoming gas, that is, the ratio of N2 to HF reaches 1:5, the ratio of N2 to HF mixed gas is adjusted to 1:1.5 again, and the gas pressure in the fixed bed reactor is adjusted to normal pressure, and the fixed bed reactor is heated to 200°C;
[0040] Repeat the above steps to increase the temperature of the fixed bed reactor by 50°C until the temperature reaches 350°C.
[0041] (4) High temperature and pressure variable ratio fluorination process:
[0042] After the fixed bed reactor is heated to 350°C, the gas pressure of the fixed bed reactor is adjusted to 0.5 MPa; the concentration of the fluorinated gas tail gas is monitored every two hours. When the HF ratio in the fluorinated tail gas reaches the ratio of the N2 and HF mixed gas before introduction, the ratio of the N2 and HF mixed gas is adjusted to 1:10.
[0043] (5) Purge and cooling process:
[0044] When the HF ratio in the fluorinated tail gas reaches the ratio of the N2 and HF mixed gas before the introduction again, the gas pressure of the fixed bed reactor is reduced to normal pressure, and then the introduction of the mixed gas is stopped, and N2 gas is introduced again to purge and cool the catalyst in the fixed bed reactor until the catalyst temperature of the fixed bed reactor is reduced to normal temperature, with an air velocity of 60 to 70 L / kg.h. The fluorination of the entire fluorination catalyst precursor is then completed.
[0045] The experimental comparison is as follows:
[0046] Take 5 groups of fluorination process catalysts disclosed in the present invention and 50 ml of fluorination process catalysts in the traditional process respectively and load them into a 19x2 nickel tube bed reactor heated by molten salt to carry out the following two-step reaction:
[0047] (1)3HF+CC1,=CHCl→CFCH,C1+2HC1;
[0048] (2)3HF+CF3CH,Cl→CF3CH,F+HCl;
[0049] in:
[0050] (1) Anhydrous hydrogen fluoride (HF) and trichloroethylene were continuously fed at a molar ratio of 10:1, and the reaction temperature was controlled at 280±5°C, the volumetric space velocity was 1300 / h, and the reaction pressure was 1.0±0.03Mpa.
[0051] (2) Anhydrous hydrogen fluoride and HCFC-133a were continuously fed at a molar ratio of 4.5:1, and the reaction temperature was controlled at 350±5°C, the volumetric space velocity was 1320 / h, and the reaction pressure was 1.0±0.03Mpa.
[0052] The specific comparison is as follows:
[0053]
[0054] By comparison, it can be seen that the fluorination method of a fluorination catalyst precursor disclosed in the present invention can improve the conversion rate of the fluorination catalyst, and the conversion rate can reach 30-35%; and during the fluorination process of the fluorination catalyst precursor, the catalyst is less damaged, the hardness does not decrease significantly, and the service life of the catalyst can reach 3 years.
[0055] Through the above manner, the fluorination method of a fluorination catalyst precursor provided by the present invention achieves the purpose of improving the conversion rate of the catalyst, improving the production quality of the catalyst precursor and extending the service life of the catalyst by providing a new fluorination method of a fluorination catalyst precursor that sequentially undergoes a low-temperature purging process, a pressurized low-temperature fluorination process, a temperature-raising variable ratio fluorination process and a purging and cooling process.
[0056] The above is only a preferred embodiment of the fluorination method of a fluorination catalyst precursor disclosed in the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the creative concept of the present invention, which all fall within the scope of protection of the present invention.
Claims
1. A method for fluorination of a fluorination catalyst precursor, characterized in that: It includes the following steps: (1) Perform low temperature purge; (2) Pressurized low-temperature fluorination process; (3) Temperature-increasing variable ratio fluorination process; (4) Purge and cooling process.
2. The method for fluorination of a fluorination catalyst precursor according to claim 1, characterized in that: Step (1) is specifically: adding a fluorination catalyst precursor into a fixed bed reactor, heating to 100-120° C., and continuously introducing N2 gas to purge the fluorination catalyst precursor; After N2 gas has been passed for a period of time, a mixed gas of N2 and HF is continuously introduced.
3. The method for fluorination of a fluorination catalyst precursor according to claim 2, characterized in that: The contact time between nitrogen and catalyst is 1 to 2 hours, and the space velocity is 60 to 70 L / kg.h; the temperature of the N2 and HF mixed gas is maintained at 100 to 120°C, and the space velocity is 50 to 55 L / kg.h.
4. The method for fluorination of a fluorination catalyst precursor according to claim 2, characterized in that: During the process of introducing the mixed gas of N2 and HF, the concentration of the tail gas of fluorinated gas was monitored once every hour; In the initial case, N2 and HF are mixed at a ratio of 1:1.5; when it is detected that the ratio of N2 to HF in the exhaust gas reaches 1:1.5, the ratio of the input mixed gas is gradually adjusted to 1:2.5; when the exhaust gas concentration is consistent with the ratio of the introduced gas again, the ratio of the input mixed gas is gradually adjusted to 1:
5.
5. The method for fluorination of a fluorination catalyst precursor according to claim 1, characterized in that: Step (2) is specifically: the gas pressure in the fixed bed reactor is increased to 0.2 MPa, and after a period of time, the gas pressure in the fixed bed reactor is further increased to 0.3 MPa, and after a period of time, the gas pressure in the fixed bed reactor is further increased to 0.5 MPa.
6. The method for fluorination of a fluorination catalyst precursor according to claim 1, characterized in that: Step (3) is specifically as follows: when the proportion of HF in the fluorinated tail gas reaches the proportion of the N2 and HF mixed gas before introduction, the proportion of the N2 and HF mixed gas is adjusted to 1:1.5, and at the same time, the gas pressure in the fixed bed reactor is adjusted to normal pressure, and the fixed bed reactor is heated to 150°C; When the temperature of the fixed bed reactor reaches 150°C, the ratio of N2 to HF mixed gas is adjusted to 1:5; When the HF ratio in the fluorinated tail gas reaches the ratio of the N2 and HF mixed gas before introduction, the ratio of the N2 and HF mixed gas is adjusted to 1:1.5 again, and the fixed bed reactor is heated to 200°C; The above steps were repeated until the fixed bed reactor was heated to 350°C with 50°C as a node.
7. The method for fluorination of a fluorination catalyst precursor according to claim 6, characterized in that: The fixed bed reactor heating rate is 3-5℃ / h.
8. The method for fluorination of a fluorination catalyst precursor according to claim 6, characterized in that: After step (3), a high-temperature pressurized variable ratio fluorination process is provided, specifically: after the fixed bed reactor is heated to 350°C, the gas pressure of the fixed bed reactor is increased to 0.5 MPa, and when the HF ratio in the fluorination tail gas reaches the ratio of the N2 and HF mixed gas before introduction, the ratio of the N2 and HF mixed gas (V) is adjusted to 1:
10.
9. The method for fluorination of a fluorination catalyst precursor according to claim 1, characterized in that: Step (4) is specifically as follows: reducing the gas pressure of the fixed bed reactor to normal pressure, then stopping the mixed gas, and re-introducing N2 gas to purge and cool the catalyst in the fixed bed reactor until the catalyst temperature of the fixed bed reactor drops to normal temperature, with an air velocity of 60 to 70 L / kg.h.