阅读说明：本技术 一种用于1，1，1，2-四氟乙烷气相氟化的催化剂及其制备方法 (Catalyst for gas phase fluorination of 1,1,1, 2-tetrafluoroethane and preparation method thereof ) 是由 赵恒军 黄理明 费益军 段誉 张伟 于 2020-12-21 设计创作，主要内容包括：一种用于1,1,1,2-四氟乙烷气相氟化的催化剂的制备方法,所述催化剂由主催化剂、助催化剂和载体组成,化学式为Cr-2O-3/Al-2O-3/M-xA-y,其中,M-xA-y为助催化剂,M表示为助催化剂中金属阳离子,A表示为助催化剂中阴离子,x为金属阳离子原子数,y为阴离子原子数,将制备好的催化剂与目前使用中的催化剂Cr-2O-3/Al-2O-3/MgO同时应用于R134a中,从而本发明用于1,1,1,2-四氟乙烷气相氟化的催化剂具有反应温度低、活性高、稳定性好的优点。(A process for preparing the catalyst used for gas-phase fluoridation of 1,1,1, 2-tetrafluoroethane is composed of primary catalyst, cocatalyst and carrier 2 O 3 /Al 2 O 3 /M x A y Wherein M is x A y As cocatalyst, M is metal cation in the cocatalyst, A is anion in the cocatalyst, x is the atom number of the metal cation, y is the atom number of the anion, and the prepared catalyst and the currently used catalyst Cr are mixed 2 O 3 /Al 2 O 3 The simultaneous use of/MgO in R134a results in the invention being used for the gas phase of 1,1,1, 2-tetrafluoroethaneThe fluoridated catalyst has the advantages of low reaction temperature, high activity and good stability.)

1. A catalyst for the gas phase fluorination of 1,1,1, 2-tetrafluoroethane, characterised in that: the catalyst consists of a main catalyst, a cocatalyst and a carrier, and has a chemical formula of Cr₂O₃/Al₂O₃/M_xA_yWherein M is_xA_yAs the cocatalyst, M represents the metal cation in the cocatalyst, A represents the anion in the cocatalyst, x represents the atom number of the metal cation, and y represents the atom number of the anion.

2. A catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane according to claim 1, characterised in that: the metal cation in the cocatalyst comprises Mg²⁺，Mn²⁺，Zn²⁺，Ni²⁺，Hg²⁺，Sb³⁺，Y³⁺，Ti⁴⁺，Fe²⁺，Fe³⁺Two or more of them are combined.

3. A catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane according to claim 1, characterised in that: the anion in the cocatalyst comprises O^2-，Cl^-，F^-，Br^-One or more of the above components in combination.

4. A process for the preparation of a catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane, which comprises: the method comprises the following steps:

the method comprises the following steps: mixing Cr (NO)₃)₃·9H₂O、Al(NO₃)₃·9H₂Preparing O into a first mixed solution of Mg (NO) with deionized water₃)₂·6H₂Preparing a second mixed solution with the pH of about 2 by using O, hydrochloric acid and other metal salts, and preparing a 10% ammonia water solution;

step two: adding the second mixed solution into the first mixed solution under the stirring state, then dropwise adding 10% ammonia water solution until the pH value is about 10, reacting for 1-5 h at 20-80 ℃, and aging for 24 h;

step three: filtering the liquid in the second step, washing the filter cake with deionized water until the filtrate is neutral, drying for 10h at 100-150 ℃, roasting for 2-4 h at 400-1100 ℃ in air, and extruding into a cylinder to obtain a catalyst precursor;

step four: introducing nitrogen into the catalyst precursor obtained in the step three at the temperature of 300-500 ℃ for dilution, performing HF activation treatment for 3-5 h, and then introducing nitrogen to reduce the temperature to room temperature to obtain the gas-phase fluorination catalyst Cr₂O₃/Al₂O₃/M_xA_y。

5. The process for the preparation of a catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane according to claim 4, which comprises: the other metal salt in the step one is Mg²⁺，Mn²⁺，Zn²⁺，Ni²⁺，Hg²⁺，Sb³⁺，Y³⁺，Ti⁴⁺，Fe²⁺，Fe³⁺Nitrate, carbonate and halide of (a).

6. The process for the preparation of a catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane according to claim 4, which comprises: n (cr) in the first step: n (Al) is 1 to 3: 1.

7. the process for the preparation of a catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane according to claim 4, which comprises: the reaction temperature in the second step is 50-70 ℃, and the reaction time is 1-2 h.

8. The process for the preparation of a catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane according to claim 4, which comprises: the drying temperature in the third step is 110-130 ℃, and the roasting temperature is 400-600 ℃.

9. The process for the preparation of a catalyst for the gas-phase fluorination of 1,1,1, 2-tetrafluoroethane according to claim 4, which comprises: and the activation temperature in the fourth step is 350-400 ℃, and the activation time is 3-4 h.

Technical Field

The invention relates to the field of modification preparation of gas phase fluorination catalysts, in particular to a catalyst for gas phase fluorination of 1,1,1, 2-tetrafluoroethane and a preparation method thereof.

Background

The ODP value of 1,1,1, 2-tetrafluoroethane (HFC-134a) is 0, the non-toxic, non-inflammable, and has good safety performance, the refrigerating capacity and efficiency are similar to those of difluorodichloromethane (CFC-12), and the product is the best environmental protection substitute of CFC-12 internationally recognized at present. There are dozens of reported preparation routes, but the factors such as raw material sources, processes, three wastes and the like are comprehensively considered, and two synthesis routes, namely a trichloroethylene route and a tetrachloroethylene route, are mainly adopted in the actual industrial production. The fluorination process mainly adopted is a liquid phase fluorination method and a gas phase fluorination method or a combination of the two. Compared with the liquid phase fluorination method, the gas phase fluorination method has the advantages of low pressure and difficult corrosion, but has the defects of low conversion rate, high energy consumption, short service life of the catalyst and the like. The catalyst used in the gas phase fluorination process is generally supported Cr₂O₃，CrF₃，CrCl₃The single-pass conversion rates of trichloroethylene and 1,1, 1-trifluoro-2-chloroethane are 93% and 10% respectively, the reaction temperature is about 350 ℃, and the single service life of the catalyst is about 1000 h. In order to increase the conversion rate and reduce the energy consumption, other metal ions are generally introduced into the catalyst to improve various performances of the catalyst.

Many reports are published on modification of gas phase fluorination catalysts, and most of them mainly include oxides, chlorides or fluorides doped with non-variable valence metals, while few reports are reported on doping of variable valence metals in liquid phase fluorination catalysts. WO9008755 discloses a catalyst of cobalt or chromium metal oxide supported on aluminium fluoride or alumina; EP0449617 discloses a zinc or nickel doped chromia catalyst; CN1082019 discloses a chromium-based catalyst containing Cr, Ga, O and F; ru2243961 discloses a catalyst of chromium and magnesium oxide; he jun et al reported a Cr/Y type catalyst. The conversion rate and the service life of the catalyst can be improved by doping the metals, but the reaction temperature is not changed greatly and is still 350-370 ℃, and the reaction temperature can often cause the self-polymerization of olefin in the raw materials, increase impurities and reduce the service life of the catalyst.

Disclosure of Invention

In order to solve the technical problems, the invention provides a gas phase fluorination rate catalyst for 1,1,1, 2-tetrafluoroethane and a preparation method thereof, which improve the performance of the catalyst by doping the lower oxide and fluoride of variable-valence metal, and achieve the purposes of reducing the reaction temperature, improving the reaction activity and prolonging the service life of the catalyst.

The purpose of the invention is realized by the following technical scheme on one hand:

a catalyst for gas-phase fluorination of 1,1,1, 2-tetrafluoroethane is composed of main catalyst, cocatalyst and carrier, and has the chemical formula of Cr₂O₃/Al₂O₃/M_xA_yWherein M is_xA_yAs the cocatalyst, M represents the metal cation in the cocatalyst, A represents the anion in the cocatalyst, x represents the atom number of the metal cation, and y represents the atom number of the anion.

Further, the metal cation in the cocatalyst comprises Mg²⁺，Mn²⁺，Zn²⁺，Ni²⁺，Hg²⁺，Sb³⁺，Y³⁺，Ti⁴⁺，Fe²⁺，Fe³⁺Two or more of them are combined.

Further, the anion in the cocatalyst comprises O^2-，Cl^-，F^-，Br^-One or more of the above components in combination.

The other aspect of the object of the invention is realized by the following technical scheme:

a process for the preparation of a catalyst for the gas phase fluorination of 1,1,1, 2-tetrafluoroethane which comprises the steps of:

the method comprises the following steps: mixing Cr (NO)₃)₃·9H₂O、Al(NO₃)₃·9H₂Preparing O into a first mixed solution of Mg (NO) with deionized water₃)₂·6H₂Preparing a second mixed solution with the pH of about 2 by using O, hydrochloric acid and other metal salts, and preparing a 10% ammonia water solution;

step two: adding the second mixed solution into the first mixed solution under the stirring state, then dropwise adding 10% ammonia water solution until the pH value is about 10, reacting for 1-5 h at 20-80 ℃, and aging for 24 h;

step three: filtering the liquid in the second step, washing the filter cake with deionized water until the filtrate is neutral, drying for 10h at 100-150 ℃, roasting for 2-4 h at 400-1100 ℃ in air, and extruding into a cylinder to obtain a catalyst precursor;

step four: introducing nitrogen into the catalyst obtained in the step three at the temperature of 300-500 ℃ for dilution, performing HF activation treatment for 3-5 hours, and then introducing nitrogen to reduce the temperature to room temperature to obtain the gas phase fluorination catalyst Cr₂O₃/Al₂O₃/M_xA_y。

Further, the other metal salt in the first step is Mg²⁺，Mn²⁺，Zn²⁺，Ni²⁺，Hg²⁺，Sb³⁺，Y³⁺，Ti⁴⁺，Fe²⁺，Fe³⁺Nitrate, carbonate and halide of (a).

Further, n (cr) in the first step: n (Al) is 1 to 3: 1.

further, the reaction temperature in the second step is 50-70 ℃, and the reaction time is 1-2 hours.

Further, the drying temperature in the third step is 110-130 ℃, and the roasting temperature is 400-600 ℃.

Further, the activation temperature in the fourth step is 350-400 ℃, and the activation time is 3-4 hours.

Compared with the prior art, the invention has the following beneficial effects:

(1) the reaction temperature of the 1,1,1, 2-tetrafluoroethane gas phase fluorination catalyst prepared by the invention is lower than that of the original catalyst, so that the energy consumption in the reaction process is greatly reduced, and the occurrence of side reactions is reduced.

(2) The 1,1,1, 2-tetrafluoroethane gas phase fluorination catalyst prepared by the invention has higher activity, and the conversion per pass of the reaction is obviously increased.

(3) The 1,1,1, 2-tetrafluoroethane gas phase fluorination catalyst prepared by the invention reduces the generation of olefin due to the reduction of the reaction temperature, so that the catalyst is more stable and has longer service life.

Detailed Description

The following describes embodiments of the present invention in detail and completely. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and therefore, only serve as a part of the implementation examples, and the protection scope of the present invention is not limited thereby. Based on the implementation examples in the present invention, other implementation examples obtained by a person of ordinary skill in the art without any creative effort belong to the protection scope of the present invention.

Example 1

40g (0.1mol) of Cr (NO)₃)₃·9H₂O、25g(0.067mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution with deionized water, and mixing 12.8g (0.05mol) of Mg (NO)₃)₂·6H₂Preparing a mixed solution from the O and deionized water, stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; mixing the second mixed solution and the first mixed solution under stirring, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, filling the cylinder into a stainless steel tube, heating to 350 ℃, and introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst Cr₂O₃/Al₂O₃/M_xA_y。

The fluorination catalysts obtained in example 1 were filled in tubular reactors respectively at 280 ℃ and 350 ℃ to perform HCFC-133a continuous fluorination experiment, (HF: HCFC133 a: 5: 1, residence time 20s) reaction products were washed with water and alkali, and then detected by GC, and the conversion and impurity content were measured as shown in tables one and two.

In the case of the 280 ℃ reaction, the conversion of less than 6% and the HFC-134a selectivity of less than 99.47% occur after 1500h of use of the catalyst in example 1.

Example 2

40g (0.1mol) of Cr (NO)₃)₃·9H₂O，25g(0.067mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution with deionized water, and mixing 12.8g (0.05mol) of Mg (NO)₃)₂·6H₂O，11.4g(0.05mol)SbCl₃Preparing a mixed solution by using deionized water, stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; mixing the second mixed solution and the first mixed solution under stirring, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, filling the cylinder into a stainless steel tube, heating to 350 ℃, and introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst Cr₂O₃/Al₂O₃/M_xA_y。

The catalyst obtained in example 2 was filled in a tubular reactor at 280 ℃ and 350 ℃ respectively to conduct a continuous fluorination experiment of HCFC-133a, (HF: HCFC133 a: 5: 1, residence time 20s) reaction product, and the conversion rate and impurity content were measured by GC after water washing and alkali washing, as shown in tables one and two.

Under the condition of 280 ℃ reaction, the conversion rate is lower than 6 percent and the selectivity of HFC-134a is lower than 99.47 percent only when the catalyst in example 2 is used for more than 2000 hours.

Example 3

40g (0.1mol) of Cr (NO)₃)₃·9H₂O，37.5g(0.1mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution with deionized water, and mixing 12.8g (0.05mol) of Mg (NO)₃)₂·6H₂O，11.4g(0.05mol)SbCl₃Preparing a mixed solution by using deionized water, stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; mixing the second mixed solution and the first mixed solution under stirring, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, filling the cylinder into a stainless steel tube, heating to 350 ℃, and introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst.

The catalyst obtained in example 3 was filled in a tubular reactor at 280 ℃ and 350 ℃ respectively to conduct a continuous fluorination experiment of HCFC-133a, (HF: HCFC133 a: 5: 1, residence time 20s) reaction product, and the conversion rate and impurity content were measured by GC after water washing and alkali washing, as shown in tables one and two.

Under the condition of 280 ℃ reaction, the conversion rate is lower than 6 percent and the selectivity of HFC-134a is lower than 99.47 percent only when the catalyst in example 3 is used for more than 2000 hours.

Example 4

40g (0.1mol) of Cr (NO)₃)₃·9H₂O，25g(0.067mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution with deionized water, and mixing 12.8g (0.05mol) of Mg (NO)₃)₂·6H₂O，8.4g(0.05mol)FeCl₃Preparing a mixed solution by using deionized water, stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; stirring the second mixed solution and the first mixed solutionMixing, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, filling the cylinder into a stainless steel tube, heating to 350 ℃, and introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst.

The catalyst obtained in example 4 was filled in a tubular reactor at 280 ℃ and 350 ℃ respectively to conduct a continuous fluorination experiment of HCFC-133a, (HF: HCFC133 a: 5: 1, residence time 20s) the reaction product was washed with water and alkali, then detected by GC, and the conversion and impurity content were measured as shown in tables one and two.

Under the condition of 280 ℃ reaction, the conversion rate is lower than 6 percent and the selectivity of HFC-134a is lower than 99.47 percent only when the catalyst in example 4 is used for more than 2000 hours.

Example 5

40g (0.1mol) of Cr (NO)₃)₃·9H₂O，25g(0.067mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution with deionized water, and mixing 12.8g (0.05mol) of Mg (NO)₃)₂·6H₂O，6.3g(0.05mol)FeCl₂Preparing a mixed solution by using deionized water,

stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; mixing the second mixed solution and the first mixed solution under stirring, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, and filling the cylinder into a stainless steel tubeHeating to 350 deg.C, introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst.

The catalyst obtained in example 5 was filled in a tubular reactor at 280 ℃ and 350 ℃ respectively to conduct a continuous fluorination experiment of HCFC-133a, (HF: HCFC133 a: 5: 1, residence time 20s) reaction product, and the conversion rate and impurity content were measured by GC after water washing and alkali washing, as shown in tables one and two.

Under the condition of 280 ℃ reaction, the conversion rate is lower than 6 percent and the selectivity of HFC-134a is lower than 99.47 percent only when the catalyst in example 5 is used for more than 2000 hours.

Example 6

40g (0.1mol) of Cr (NO)₃)₃·9H₂O，25g(0.067mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution by using deionized water, and preparing 19.7g (0.05mol) of Zn (NO)₃)₂·6H₂O，11.4g(0.05mol)SbCl₃Preparing a mixed solution by using deionized water, stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; mixing the second mixed solution and the first mixed solution under stirring, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, filling the cylinder into a stainless steel tube, heating to 350 ℃, and introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst.

The catalyst obtained in example 6 was filled in a tubular reactor at 280 ℃ and 350 ℃ respectively to conduct a continuous fluorination experiment of HCFC-133a, (HF: HCFC133 a: 5: 1, residence time 20s) reaction product, and the conversion rate and impurity content were measured by GC after water washing and alkali washing, as shown in tables one and two.

Under the condition of 280 ℃ reaction, the conversion rate is lower than 6 percent and the selectivity of HFC-134a is lower than 99.47 percent only when the catalyst in example 6 is used for more than 2000 hours.

Example 7

40g (0.1mol) of Cr (NO)₃)₃·9H₂O，25g(0.067mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution with deionized water, and mixing 12.8g (0.05mol) of Mg (NO)₃)₂·6H₂O，19.7g(0.05mol)Zn(NO₃)₂·6H₂O，11.4g(0.05mol)SbCl₃Preparing a mixed solution by using deionized water, stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; mixing the second mixed solution and the first mixed solution under stirring, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, filling the cylinder into a stainless steel tube, heating to 350 ℃, and introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst.

The catalyst obtained in example 7 was loaded in a tubular reactor and subjected to continuous fluorination experiment of HCFC-133a at 280 ℃ and 350 ℃, respectively, (HF: HCFC133 a: 5: 1, residence time 20s) reaction products were washed with water and alkali, and then detected by GC, and the conversion and impurity content were measured as shown in tables one and two.

Under the condition of 280 ℃ reaction, the conversion rate is lower than 6 percent and the selectivity of HFC-134a is lower than 99.47 percent only when the catalyst in example 7 is used for more than 2000 hours.

Example 8

40g (0.1mol) of Cr (NO)₃)₃·9H₂O，25g(0.067mol)Al(NO₃)₃·9H₂Preparing O into a first mixed solution with deionized water, and mixing 12.8g (0.05mol) of Mg (NO)₃)₂·6H₂O，19.7g(0.05mol)Zn(NO₃)₂·6H₂O，8.4g(0.05mol)FeCl₃Preparing a mixed solution by using deionized water, stirring, and dropwise adding hydrochloric acid into the mixed solution until the solid is dissolved to prepare a second mixed solution with the pH of about 2; mixing the second mixed solution and the first mixed solution under stirring, dropwise adding 10% ammonia water solution until the pH value is about 10, keeping the reaction temperature at 50 ℃, reacting for 1h, filtering, and washing a filter cake with deionized water until the filtrate is neutral; and (3) drying the filter cake at 120 ℃ overnight, placing the obtained dried solid in a muffle furnace, and roasting at 600 ℃ for 2h to obtain the catalyst precursor.

Extruding the obtained catalyst precursor into a cylinder by an extruder, filling the cylinder into a stainless steel tube, heating to 350 ℃, and introducing HF and N₂Volume ratio of about 4: 1, fluorinating the mixed gas, and introducing N after activation₂Stopping heating until no acid gas and water exist in the gas, and introducing N₂Cooling the catalyst to normal temperature to obtain the fluorination catalyst.

The catalyst obtained in example 8 was filled in a tubular reactor at 280 ℃ and 350 ℃ respectively to conduct a continuous fluorination experiment of HCFC-133a, (HF: HCFC133 a: 5: 1, residence time 20s) the reaction product was washed with water and alkali, then checked by GC, and the conversion and impurity content were measured as shown in tables one and two.

Under the condition of 280 ℃ reaction, the conversion rate is lower than 6 percent and the selectivity of HFC-134a is lower than 99.47 percent only when the catalyst in example 8 is used for more than 2000 hours.

Example 9

A catalyst for gas-phase fluorination of 1,1,1, 2-tetrafluoroethane is composed of main catalyst, cocatalyst and carrier, and has the chemical formula of Cr₂O₃/Al₂O₃/M_xA_yWherein M is_xA_yAs cocatalyst, M is a metal cation in the cocatalyst, A isShown as anions in the cocatalyst, x is the atom number of the metal cation, and y is the atom number of the anion, wherein the metal cation in the cocatalyst comprises Mg²⁺，Mn²⁺，Zn²⁺，Ni²⁺，Hg²⁺，Sb³⁺，Y³⁺，Ti⁴⁺，Fe²⁺，Fe³⁺Two or more of the above-mentioned combinations, and the anions contained in the cocatalyst are selected from O^2-，Cl^-，F^-，Br^-One or more of the above components in combination.

TABLE-conversion and selectivity at 280 ℃ for the examples

Examples	HCFC-133a conversion (%)	HFC-134a selectivity (%)
			1	9.32	99.55
2	12.16	99.73
			3	9.81	99.72
4	13.66	99.75
			5	11.25	99.67
6	10.78	99.72
			7	14.13	99.76
8	14.87	99.80

TABLE II conversion and selectivity of the examples at 350 ℃

As shown in the first and second tables, the conversion rate of the catalyst in example 1 is less than 6% and the HFC-134a selectivity is less than 99.47% after 1500h of use under the reaction condition of 280 ℃, which is the case for the catalysts in examples 2-8, and is the case for the catalysts in examples 2-8 after 2000 h. Through the experiments of the conversion rate and the selectivity, the activity of the catalyst is obviously improved after doping modification, and the stability of the catalyst is greatly improved. In order to improve the selectivity of the reaction and reduce the energy consumption. Meanwhile, the difficulty of subsequent separation is reduced, and the reaction temperature is properly selected at 280 ℃ in comprehensive consideration.

The above description is only a basic description of the present invention, and any equivalent changes made according to the technical solution of the present invention should fall within the protection scope of the present invention.