CATALYST FOR PREPARING 2,3,3,3,-TETRAFLUOROPROPENE BY GAS-PHASE HYDRODECHLORINATION

Abstract

Disclosed is a catalyst for preparing 2,3,3,3-tetrafluoropropene by gas-phase hydrodechlorination, which solves the problem of the high costs and easy deactivation of traditional chlorofluorocarbon hydrodechlorination catalysts. The disclosed catalyst is characterized in consisting of an active component and a carrier, wherein the active component is a combination of one or more of the metals: Ni, Mo, W, Co, Cr, Cu, Ce, La, Mn and Fe. The catalyst in the present invention has excellent performance, high activity, good stability and a low reaction temperature, effectively reduces reaction energy consumption, and has industrial application value.

Claims

1. A catalyst for preparing 2,3,3,3-tetrafluoropropene by gas-phase hydrodechlorination, consisting of an active component and a carrier, wherein the active component is one selected from the group consisting of metal Ni, Mo, W, Co, Cr, Cu, Ce, La, Mn, Fe, and any combination thereof; the carrier is one selected from the group consisting of an oxide, a fluoride, activated carbon and a molecular sieve; wherein the active component accounts for 0.01%-50% of the total mass of the catalyst.

2. The catalyst for preparing 2,3,3,3-tetrafluoropropene by gas-phase hydrodechlorination according to claim 1, wherein the carrier has a specific surface area of 10-2000 m.sup.2/g.

3. The catalyst for preparing 2,3,3,3-tetrafluoropropene by gas-phase hydrodechlorination according to claim 1, wherein the catalyst is used in a preparation of 2,3,3,3-tetrafluoropropene by a gas-phase selective hydrodechlorination reaction of 2-chloro-1,1,1,2-tetrafluoropropane carried out at a temperature of 100-300° C. and a reaction pressure of 0.1-2.0 MPa; a raw material gas space velocity is 20-200 h.sup.−1; and the raw material hydrogen and 2-chloro-1,1,1,2-tetrafluoropropane are in a molar ratio of 1/1-5/1.

Description

DETAILED DESCRIPTION OF ILLUSTRATED EXAMPLES

[0019] Specific embodiments of the present invention are given below, which will not limit the scope of the present invention. The performance evaluation of the catalyst used in the preparation of HFO-1234yf by hydrodechlorination according to the present invention is as follows:

[0020] Transfer 5 mL of the catalyst into a fixed-bed tubular reactor. After the catalyst bed temperature reaches 250° C., HCFC-244bb and hydrogen are introduced and contact with the catalyst bed for 4 s. The H.sub.2 pressure is 0.2 MPa, and the H.sub.2 and HCFC-244bb are in a mole ratio of 3. The product obtained after 8 hours of operation is subject to water washing and alkaline washing to remove hydrogen fluoride and hydrogen chloride, and then analyzed by gas chromatograph. The conversion rate of HCFC-244bb and the selectivity of the target product HFO-1234yf is calculated by the area normalization method.

Example 1

[0021] 9.48 g (according to 20% Ni loading amount) nickel nitrate is added to deionized water to obtain a clear solution. 9.6 g of silica in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h to obtain a Ni/SiO.sub.2 oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the precursor is heated from room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is heated from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 30.1%, and the HFO-1234yf selectivity is 50%.

Example 2

[0022] 9.48 g (according to 20% Ni loading amount) nickel nitrate is added to deionized water to obtain a clear solution. 9.6 g of activated carbon in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h to obtain a Ni/C oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the precursor is heated from the room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is heated from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 48.9%, and the HFO-1234yf selectivity is 64%.

Example 3

[0023] 9.48 g (according to a 10% Ni loading amount) nickel nitrate is added to deionized water to obtain a clear solution. 21.9 g of magnesium fluoride in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 400° C. for 4 h to obtain a Ni/MgF.sub.2 oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the precursor is heated from the room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is increased from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 35.1%, and the selectivity of HFO-1234yf is 38%.

Example 4

[0024] 9.48 g (according to a 10% Ni loading amount) nickel nitrate is added to deionized water to obtain a clear solution. 21.9 g of aluminum fluoride in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h to obtain a Ni/AlF.sub.3 oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the precursor is heated from room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is increased from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 38.7%, and the selectivity of HFO-1234yf is 38%.

Example 5

[0025] 3.52 g (according to a 20% Mo loading amount) ammonium molybdate is added to deionized water to obtain a clear solution. 7.65 g activated carbon in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h to obtain a Mo/C oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The heating program mainly comprises two steps: (1) the precursor is heated from room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is increased from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 45.7%, and the selectivity of HFO-1234yf is 51%.

Example 6

[0026] 9.8 g (according to a 10% Ni loading amount) nickel nitrate and 4.6 g (according to a 10% Mo loading amount) ammonium molybdate are added to deionized water to obtain a clear solution. 20 g of activated carbon in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h in a N.sub.2 atmosphere to obtain a Ni—Mo/C oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the temperature is heated from room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is heated from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 51.7%, and the HFO-1234yf selectivity is 59%.

Example 7

[0027] 9.8 g (according to a 10% Ni loading amount) nickel nitrate and 9.5 g (according to a 20% Cu loading amount) copper nitrate are added to deionized water to obtain a clear solution. 20 g of activated carbon in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h in a N.sub.2 atmosphere to obtain a Ni—Cu/C oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the temperature is heated from room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is heated from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 45.7%, and the HFO-1234yf selectivity is 70%.

Example 8

[0028] 7.78 g (according to a 10% Ni loading amount) nickel nitrate, 3.68 g (according to a 10% Mo loading amount) ammonium molybdate and 3.80 g (according to a 5% Cu loading amount) copper nitrate are added to deionized water to obtain a clear solution. 15 g of activated carbon in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h in a N.sub.2 atmosphere to obtain a Ni—Mo—Cu/C oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the temperature is heated from room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is heated from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 62%, and the HFO-1234yf selectivity is 63%.

Example 9

[0029] 3.73 g (according to a 10% W loading amount) ammonium metatungstate is added to deionized water to obtain a clear solution. 10.4 g of activated carbon in an equal volume was immersed in the above solution, then aged at room temperature for 12 h, dried at 120° C. for 12 h to dry the moisture, and calcined at 500° C. for 4 h in a N.sub.2 atmosphere to obtain a W/C oxide precursor. An in-situ temperature-programmed reduction is performed to prepare the catalyst. The temperature program mainly comprises two steps: (1) the temperature is heated from room temperature to a temperature of 120° C. at a heating rate of 5° C./min in a H.sub.2 atmosphere (flow rate 150 mL/min). Then the temperature is kept at 120° C. for 1 h to eliminate moisture absorbed in the catalyst precursor. (2) the temperature is heated from 120° C. to 400° C. at a heating rate of 5° C./min, and kept for 2 h to obtain a catalyst. By taking the performance evaluation of the catalyst, the conversion rate of HCFC-244bb is 25.7%, and the HFO-1234yf selectivity is 36%.

Example 10

[0030] Service life test of the catalysts prepared for preparing of HFO-1234yf by hydrodechlorination of HCFC-244bb according to the present invention.

[0031] Performing a service life test to the catalyst prepared in the example 8. 5 mL of the catalyst is loaded to perform the hydrodechlorination reaction at 250° C. The hydrogen and HCFC-244bb are introduced in a molar ratio of 3 and contact with the catalyst bed for 4 s. The reaction continues for 200 h. The product obtained is subject to water washing and alkaline washing to remove hydrogen fluoride and hydrogen chloride, and then analyzed by gas chromatograph. The results of the test are indicted in Table 1.

TABLE-US-00001 TABLE 1 Service life test Reaction HCFC-244bb HFO-1234yf time conversion rate, % selectivity, %  24 h 60.5 62.8 100 h 60.8 63.4 150 h 60.6 62.5 200 h 60.4 61.8