WO2021114480A1 - 一种hfc-23资源化利用中减少催化剂积碳的方法 - Google Patents

一种hfc-23资源化利用中减少催化剂积碳的方法 Download PDF

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WO2021114480A1
WO2021114480A1 PCT/CN2020/076371 CN2020076371W WO2021114480A1 WO 2021114480 A1 WO2021114480 A1 WO 2021114480A1 CN 2020076371 W CN2020076371 W CN 2020076371W WO 2021114480 A1 WO2021114480 A1 WO 2021114480A1
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catalyst
hfc
resource utilization
reducing carbon
carbon deposits
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PCT/CN2020/076371
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English (en)
French (fr)
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张建君
韩文锋
王术成
刘武灿
周飞翔
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浙江省化工研究院有限公司
浙江蓝天环保高科技股份有限公司
中化蓝天集团有限公司
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Priority to US17/427,554 priority Critical patent/US11878290B2/en
Priority to JP2022535667A priority patent/JP7470793B2/ja
Priority to EP20899849.2A priority patent/EP3904318A4/en
Publication of WO2021114480A1 publication Critical patent/WO2021114480A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
    • B01J27/132—Halogens; Compounds thereof with chromium, molybdenum, tungsten or polonium
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    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
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    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
    • B01J23/46—Ruthenium, rhodium, osmium or iridium
    • B01J23/462—Ruthenium
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
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    • B01J23/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals of the platinum group metals
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/64—Platinum group metals with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/652—Chromium, molybdenum or tungsten
    • B01J23/6522—Chromium
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
    • B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/8993—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with chromium, molybdenum or tungsten
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
    • B01J27/08—Halides
    • B01J27/12—Fluorides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/06—Halogens; Compounds thereof
    • B01J27/128—Halogens; Compounds thereof with iron group metals or platinum group metals
    • B01J27/13—Platinum group metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/22—Halogenating
    • B01J37/26—Fluorinating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/10—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst using elemental hydrogen
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
    • C07C17/20—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms
    • C07C17/202—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
    • C07C17/20—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms
    • C07C17/202—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction
    • C07C17/204—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction the other compound being a halogen
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C17/00—Preparation of halogenated hydrocarbons
    • C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
    • C07C17/20—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms
    • C07C17/202—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction
    • C07C17/206—Preparation of halogenated hydrocarbons by replacement by halogens of halogen atoms by other halogen atoms two or more compounds being involved in the reaction the other compound being HX

Definitions

  • the present invention relates to the resource utilization of HFC-23, in particular to a method for reducing the surface carbon of a catalyst and improving the stability of the catalyst in the resource utilization of HFC-23.
  • HFC-23 (CHF 3 , trifluoromethane, R23) is an inevitable by-product of industrial production of HFC-22 (HCFC-22, difluoromonochloromethane, R22 or CHClF 2 ). It has a strong greenhouse effect and has a global The global warming potential (GWP, Global Warming Potential) is 14,800 times that of CO 2. According to statistics, in 2013, China's HFC-23 emissions accounted for 68% of the world's emissions, and the production volume reached more than 20,000 tons, which is equivalent to the annual CO 2 emissions of 296 million tons. Therefore, the resource utilization of HFC-23 is an important topic in the realization of energy saving and emission reduction.
  • GWP Global Warming Potential
  • HFC-23 a by-product produced in the production process of HCFC-22, is generally discharged directly or processed by high temperature incineration at 1200°C.
  • direct discharge will cause environmental pollution, and the operation and equipment cost of high temperature incineration at 1200°C Higher, increase the production cost of HCFC-22.
  • the following methods are adopted in the prior art for resource utilization of HFC-23:
  • US patent US3009966A discloses a method for preparing TFE and hexafluoropropylene (HFP) by pyrolysis of trifluoromethane at 700-1090°C.
  • HFP hexafluoropropylene
  • this method produces more perfluoroisobutene (PFIB) by-products, even at the cost of lowering the yield Performing at a lower temperature will also produce a non-negligible amount of PFIB, and PFIB has extremely high toxicity and the treatment process is more complicated.
  • PFIB perfluoroisobutene
  • WO96/29296A discloses a method for co-cracking HCFC-22 and HFC-23 to form macromolecular fluoroalkanes. Although the conversion rate of HCFC-22 in this method can reach 100%, the yield of the product pentafluoroethane is only 60%. , And produce additional low-value by-products that need to be treated.
  • US patent US2003/0166981 discloses that gold is used as a catalyst, and HFC-23 and HCFC-22 are pyrolyzed to produce pentafluoroethane (HFC-125), heptafluoropropane (HFC-227ea), TFE and TFE at a temperature of 690 to 775°C. A mixture of HFP. However, this method has high pyrolysis temperature and severe reaction conditions.
  • Chinese patent CN104628513A discloses a method for converting trifluoromethane and chloroform as raw materials into HCFC-22 under the catalysis of Lewis acid.
  • the method realizes the conversion of trifluoromethane at a relatively low temperature (below 400° C.) through intermolecular fluorine and chlorine exchange.
  • this method uses a strong Lewis acid catalyst, which has poor catalyst stability and is very prone to deactivation due to carbon deposition and sintering.
  • Chinese patent CN109748775A discloses that in the presence of MgF 2 , Al 2 O 3 , partially fluorinated alumina or AlF 3 catalysts, trifluoromethane and dichloromethane are reacted to convert to higher value difluoromethane, and the reaction continues at the same time. Add Cl 2 , CCl 4 , H 2 , O 2 , CO 2 , O 3 and nitrogen oxide promoting gas. Although the method improves the stability of the catalyst, the selectivity of the by-product CFC-12 is greatly improved, reaching 2% to 8%, and the product selectivity is reduced.
  • the present invention proposes a method for reducing the carbon deposit on the catalyst and improving the stability and life of the catalyst.
  • the above-mentioned fluorine-chlorine exchange products include difluoromonochloromethane (HCFC-22) and monofluorodichloromethane (HCFC-21).
  • HCFC-22 difluoromonochloromethane
  • HCFC-21 monofluorodichloromethane
  • the catalyst for the fluorine-chlorine exchange reaction includes a main catalyst and a noble metal, the noble metal is selected from at least one of Pt, Pd, Ru, Au or Rh, and the addition amount is 0.01-2wt%; preferably, the noble metal is Pt or Pd, the addition amount is 0.1-0.5wt%.
  • hydrogen gas is introduced.
  • the method of feeding is: hydrogen, HFC-23, and halogenated hydrocarbon are formed into a mixed gas and then continuously fed into the catalyst bed.
  • the molar ratio of HFC-23, halogenated hydrocarbon and hydrogen is 1:1 ⁇ 3:0.01 ⁇ 0.5, which is preferred .
  • the molar ratio of HFC-23, halogenated hydrocarbon and hydrogen is 1:1.5 ⁇ 2.5:0.05 ⁇ 0.2.
  • Adding precious metals to the main catalyst can more effectively adsorb H 2 , and realize in-situ hydrogenation of carbon deposits into CH 4 .
  • the catalyst also includes a metal oxide, and the metal oxide is selected from at least one metal oxide selected from K, Na, Fe, Co, Cu, Ni, Zn, or Ti, and the addition amount is 0.1-5wt%, and the addition method
  • the conventional method for preparing the existing catalyst can be used, such as: physical grinding with the main catalyst, or incorporation of the metal salt solution precursor wet-mixing method or dipping method and then roasting.
  • the metal oxide is selected from metal oxides of Fe, Co, Ni or Zn, and the addition amount is 0.5-2 wt%.
  • the main catalyst is a chromium, aluminum, magnesium-based catalyst or a catalyst in which chromium, aluminum, and magnesium are supported on activated carbon/graphite; preferably, the main catalyst is selected from Cr 2 O 3 , Cr 2 O 3 /Al 2 O 3 At least one of Cr 2 O 3 /AlF 3 , Cr 2 O 3 /C, MgO, MgO/Al 2 O 3 , MgO/AlF 3 , MgO/AlF 3 , Al 2 O 3 or AlF 3 .
  • the catalyst of the present invention needs to be pretreated.
  • the noble metal is added after the pretreatment of the main catalyst is completed;
  • the catalyst includes a main catalyst, a noble metal and a metal oxide, the noble metal is added to the main catalyst.
  • the catalyst is pretreated after adding metal oxides, and noble metals are added after the pretreatment is completed.
  • the specific pretreatment process includes the following steps:
  • the halogenated hydrocarbon in the above-mentioned fluorine-chlorine exchange reaction is chloroform or a mixture containing chloroform.
  • the fluorine-chlorine exchange reaction conditions are: the molar ratio of HFC-23 and halogenated hydrocarbon is: 1 ⁇ 1:3, and the reaction temperature is 250 ⁇ 400 °C, the reaction pressure is: 0.1 ⁇ 3bar, the residence time is 4 ⁇ 50s.
  • the molar ratio of HFC-23 and halogenated hydrocarbon is 1:1-2, the reaction temperature is 300-360°C, the reaction pressure is 0.1-2 bar, and the residence time is 4-12s.
  • the present invention has the following beneficial effects:
  • the Japanese invention adds precious metals to the main catalyst, and during the fluorine-chlorine exchange reaction, the hydrogen is mixed with the feed gas (HFC-23 and halogenated hydrocarbon) and then continuously passed into the catalyst bed to promote the hydrogen on the surface of the catalyst.
  • Adsorption promotes in-situ hydrogenation of carbon on the surface of the catalyst to generate CH 4 , thereby eliminating the carbon deposit on the catalyst in situ and improving the stability and life of the catalyst.
  • HFC-23, halogenated hydrocarbons (chloroform), HCFC-22 and HCFC-21 in the reaction system can be used as fire extinguishing agents or refrigerants, they have poor combustion performance. Therefore, highly reactive hydrogen is used to inhibit the carbon deposit of the catalyst and react to the target. The performance impact is small, and the carbon deposit can be selectively eliminated;
  • the present invention accelerates the desorption of the products HCFC-22 and HCFC-21 on the surface of the catalyst by adding metal oxides to the catalyst, thereby inhibiting the disproportionation reaction on the surface of the catalyst, reducing the carbon deposition caused by side reactions, and improving Improve the stability and life of the catalyst;
  • the present invention can not only inhibit the generation of carbon deposits, but also eliminate the carbon deposits in situ, exert a better synergistic effect, and significantly improve the stability of the catalyst. Performance, prolong the service life of the catalyst.
  • Preparation of the catalyst pretreatment of the chromium trioxide catalyst (main catalyst), the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours under a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere, Treat at 300°C for 5 hours; 3) Purge with nitrogen to cool down. Pour the pre-fluorinated catalyst into n-hexane and stir to disperse evenly. Add Ru nano colloidal dispersion dropwise to control the Ru loading mass content to 0.1%. After stirring continuously for 4 hours, let it stand and the upper layer of the solution becomes transparent.
  • HFC-23 resource utilization pass trifluoromethane, chloroform and hydrogen at a ratio of 1:1.5:0.2 (molar ratio) into a reactor equipped with 50ml catalyst 1, reaction temperature 310°C, reaction pressure 1bar, residence time 5s, and fluorine Chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 27.1%
  • the selectivity of HCFC-22 is 45.7%
  • the selectivity of HCFC-21 is 53.1%.
  • the tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 905 hours, indicating that it was loaded with a precious metal Ru catalyst with hydrogenation performance, and hydrogen gas could be used to eliminate carbon deposits and achieve in-situ regeneration of the catalyst.
  • Preparation of the catalyst pretreatment of the chromium trioxide catalyst (main catalyst), the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours under a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere, Treat at 300°C for 5 hours; 3) Purge with nitrogen to cool down. Pour the pre-fluorinated catalyst into n-hexane and stir to disperse evenly. Add Pt nano colloidal dispersion dropwise to control the loading of Pt to 0.1wt%. After stirring continuously for 4 hours, let it stand and the upper layer of the solution becomes transparent and clear.
  • HFC-23 resource utilization pass trifluoromethane, chloroform and hydrogen into the reactor equipped with 50ml catalyst 2 at 1:1.5:0.2 (molar ratio), reaction temperature 310°C, reaction pressure 1bar, residence time 5s, fluorine Chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 27.9%
  • the selectivity of HCFC-22 is 45.9%
  • the selectivity of HCFC-21 is 52.9%.
  • the tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 989h, indicating that it was loaded with a precious metal Pt catalyst with hydrogenation performance, and at the same time, hydrogen can be used to eliminate carbon deposits and achieve in-situ regeneration of the catalyst.
  • Preparation of the catalyst pretreatment of the chromium trioxide catalyst (main catalyst), the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours under a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere, Treat at 300°C for 5 hours; 3) Purge with nitrogen to cool down. Pour the pre-fluorinated catalyst into n-hexane and stir to disperse evenly. Add Pd nano colloidal dispersion dropwise to control the mass loading of Pd at 0.1%. After stirring continuously for 4 hours, let it stand and the upper layer of the solution becomes transparent and clear.
  • HFC-23 resource utilization pass trifluoromethane, chloroform and hydrogen into a reactor equipped with 50ml catalyst 3 at 1:1.5:0.2 (molar ratio), the reaction temperature is 310°C, the reaction pressure is 1bar, the residence time is 5s, and the fluorine is carried out. Chlorine exchange reaction. The conversion rate of trifluoromethane is 26.9%, the selectivity of HCFC-22 is 43.9%, and the selectivity of HCFC-21 is 54.7%. The tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 956h, indicating that it was loaded with a precious metal Pd catalyst with hydrogenation performance, and at the same time, hydrogen can be used to eliminate carbon deposits and achieve in-situ regeneration of the catalyst.
  • the conversion rate of trifluoromethane is 26.8%, the selectivity of HCFC-22 is 45.4%, and the selectivity of HCFC-21 is 53.9%.
  • the tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 978h, indicating that the noble metal Pt catalyst with hydrogenation performance was supported on the AlF 3 main catalyst, and the carbon deposits could be eliminated in situ after the hydrogen was passed in, and the regeneration of the catalyst was realized.
  • this embodiment is the same as that of embodiment 2, except that the loading amount of Pt in embodiment 2 is reduced from 0.1 wt% to 0.05 wt%, and the prepared catalyst is denoted as catalyst 5.
  • the conversion rate of trifluoromethane is 27.0%, the selectivity of HCFC-22 is 45.5%, and the selectivity of HCFC-21 is 53.1%.
  • the tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 817 hours. Compared with the result of Example 2, it shows that the loading amount of the hydrogenation precious metal catalyst was reduced to 0.05 wt%, and the ability to eliminate carbon deposits in situ was reduced.
  • this embodiment is the same as that of embodiment 2, the only difference is that the loading amount of Pt in embodiment 2 is increased from 0.1 wt% to 1.0 wt%, and the prepared catalyst is denoted as catalyst 6.
  • the conversion rate of trifluoromethane is 26.8%, the selectivity of HCFC-22 is 45.6%, and the selectivity of HCFC-21 is 53.2%.
  • the tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 854 hours. Compared with the results of Example 2, it shows that when the hydrogenation noble metal catalyst loading is increased to 1.0%, the ability to eliminate carbon deposits in situ is also reduced.
  • chromium trioxide (main catalyst) and cobalt trioxide powder are mixed through grinding, and the mass content of Co is controlled to 1.0% to obtain 1.0% Co/Cr 2 O 3 catalyst precursor.
  • the 1.0% Co/Cr 2 O 3 catalyst precursor is pretreated.
  • the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours in a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere, Treat at 300°C for 5 hours; 3) Purge with nitrogen to cool down.
  • HFC-23 resource utilization pass trifluoromethane, chloroform and hydrogen into a reactor equipped with 50ml catalyst 7 at a ratio of 1:1.5:0.1 (molar ratio).
  • the reaction temperature is 310°C
  • the reaction pressure is 1bar
  • the residence time is 5s.
  • the conversion rate of trifluoromethane is 26.7%
  • the selectivity of HCFC-22 is 48.6%
  • the selectivity of HCFC-21 is 50.3%.
  • the tail gas also contains a small amount of by-product CFC-12 and other gases and trace amounts of methane and other gases.
  • the catalyst was significantly deactivated after 2063 hours, indicating that there is a synergistic effect when the main chromium trioxide catalyst supports the noble metal Pt with hydrogenation performance and Co to avoid the carbon deposition reaction, and the catalyst life is longer than the case of single addition of noble metals or single addition of metal oxides .
  • Preparation of the catalyst aluminum fluoride (main catalyst) and cobalt trioxide powder are mixed through grinding, and the mass content of Co is controlled to be 1.0% to obtain 1.0% Co/AlF 3 catalyst precursor.
  • the 1.0% Co/AlF 3 catalyst precursor is pretreated.
  • the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours under a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere at 300°C Treat for 5 hours; 3) Purge with nitrogen to cool down.
  • HFC-23 resource utilization pass trifluoromethane, chloroform and hydrogen into a reactor equipped with 50ml catalyst 8 at 1:1.5:0.2 (molar ratio), reaction temperature 310°C, reaction pressure 1bar, residence time 5s, and fluorine Chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 26.7%
  • the selectivity of HCFC-22 is 44.6%
  • the selectivity of HCFC-21 is 54.3%.
  • the tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 2145h, indicating that the main aluminum fluoride catalyst supports the noble metal Pt with hydrogenation performance and Co to avoid the carbon deposition reaction, and there is a synergistic effect, and the catalyst life is longer than that of a single addition of noble metal or a single addition of metal oxides.
  • the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours in a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) treatment at 300°C for 5 hours in a hydrogen fluoride atmosphere; 3) Purge with nitrogen to cool down.
  • the catalyst after pretreatment is denoted as B1.
  • HFC-23 resource utilization pass trifluoromethane and chloroform at a ratio of 1:1.5 (molar ratio) into a reactor equipped with 50ml of catalyst B1, at a reaction temperature of 310°C, a reaction pressure of 1bar, and a residence time of 5s to carry out the fluorine-chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 25.6%
  • the selectivity of HCFC-22 is 44.4%
  • the selectivity of HCFC-21 is 55.2%
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst was significantly deactivated after 340h, and the catalyst was taken out and found to be obviously blackened with serious carbon deposition.
  • this comparative example is the same as that of comparative example 1, except that the catalyst chromium trioxide is replaced with AlF 3 , and the pretreated catalyst is denoted as B2.
  • the conversion rate of trifluoromethane is 25.8%
  • the selectivity of HCFC-22 is 44.2%
  • the selectivity of HCFC-21 is 54.9%
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst was significantly deactivated after 395h, and the catalyst was taken out and found to be obviously blackened with serious carbon deposition.
  • Preparation of the catalyst pretreatment of the chromium trioxide catalyst (main catalyst), the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours under a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere, Treat at 300°C for 5 hours; 3) Purge with nitrogen to cool down.
  • HFC-23 resource utilization pass trifluoromethane, chloroform and hydrogen into the reactor equipped with 50ml catalyst 2 at 1:1.5:0.2 (molar ratio), reaction temperature 310°C, reaction pressure 1bar, residence time 5s, fluorine Chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 26.3%, the selectivity of HCFC-22 is 45.6%, and the selectivity of HCFC-21 is 53.2%.
  • the tail gas also contains a small amount of by-product gases such as CFC-12 and trace amounts of methane.
  • the catalyst was significantly deactivated after 321h, indicating that the noble metal Ag was loaded on the main catalyst, and hydrogen was not able to achieve in-situ regeneration of the catalyst.
  • the chromium oxide and cobalt oxide powder is produced by grinding and mixing the control Co content of 1.0 mass% to obtain 1.0% Co / Cr 2 O 3 catalyst precursor, the 1.0% Co / Cr 2 O 3
  • the catalyst precursor is pretreated.
  • the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours in a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) treatment at 300°C for 5 hours in a hydrogen fluoride atmosphere; 3) nitrogen blowing Sweep to cool down.
  • the pretreated catalyst is denoted as B4.
  • HFC-23 resource utilization pass trifluoromethane and chloroform at 1:1.5 (molar ratio) into a reactor equipped with 50ml catalyst B4, reaction temperature 310°C, reaction pressure 1bar, residence time 5s, and carry out fluorine-chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 26.6%
  • the selectivity of HCFC-22 is 44.3%
  • the selectivity of HCFC-21 is 54.7%
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst was significantly deactivated after 973h. The experimental results show that the addition of Co 2 O 3 can effectively improve the stability and life of the catalyst.
  • Catalyst preparation Chromium trioxide and iron trioxide powder are mixed through grinding, and the mass content of Fe is controlled to 1.0% to obtain a precursor of 1.0% Fe/Cr 2 O 3 catalyst.
  • the 1.0% Fe/Cr 2 O 3 catalyst precursor is pretreated.
  • the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours in a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere, Treat at 300°C for 5 hours; 3) Purge with nitrogen to cool down.
  • the pre-treated catalyst is denoted as B5.
  • HFC-23 resource utilization pass trifluoromethane and chloroform at 1:1.5 (molar ratio) into a reactor equipped with 50ml catalyst B5, reaction temperature 310°C, reaction pressure 1bar, residence time 5s, and carry out fluorine-chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 26.3%, the selectivity of HCFC-22 is 44.7%, and the selectivity of HCFC-21 is 54.4%.
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst is significantly deactivated after 861h . The experimental results show that the addition of Fe 2 O 3 can effectively improve the stability and life of the catalyst.
  • Catalyst preparation mixing chromium trioxide and nickel trioxide powder through milling, and controlling the mass content of Ni to 1.0% to obtain a 1.0% Ni/Cr 2 O 3 catalyst precursor.
  • the 1.0% Ni/Cr 2 O 3 catalyst precursor is pretreated.
  • the pretreatment process includes: 1) fluorination treatment at 250°C for 2 hours in a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen; 2) under a hydrogen fluoride atmosphere, Treat at 300°C for 5 hours; 3) Purge with nitrogen to cool down.
  • the pre-treated catalyst is denoted as B6.
  • HFC-23 resource utilization pass trifluoromethane and chloroform at 1:1.5 (molar ratio) into a reactor equipped with 50ml catalyst B6, reaction temperature 310°C, reaction pressure 1bar, residence time 5s, and carry out fluorine-chlorine exchange reaction.
  • the conversion rate of trifluoromethane is 25.3%, the selectivity of HCFC-22 is 43.7%, and the selectivity of HCFC-21 is 55.4%.
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst is significantly deactivated after 758h. .
  • the experimental results show that the addition of Ni 2 O 3 can effectively improve the stability and life of the catalyst.
  • this comparative example is the same as that of comparative example 4, except that the catalyst chromium trioxide is replaced with aluminum fluoride, and the pretreated catalyst is denoted as B7.
  • the conversion rate of trifluoromethane is 26.3%, the selectivity of HCFC-22 is 44.1%, and the selectivity of HCFC-21 is 54.9%.
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst is significantly deactivated after 965h .
  • the experimental results show that adding Co 2 O 3 to the main catalyst AlF 3 can effectively improve the stability and life of the catalyst.
  • the conversion rate of trifluoromethane is 26.4%
  • the selectivity of HCFC-22 is 44.1%
  • the selectivity of HCFC-21 is 54.9%.
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst is significantly deactivated after 654h . Compared with Comparative Example 4, the experimental results indicate that the ability to improve the stability and life of the catalyst is weakened when the mass content of Co 2 O 3 is 0.1%.
  • the conversion rate of trifluoromethane is 26.3%, the selectivity of HCFC-22 is 44.4%, and the selectivity of HCFC-21 is 54.3%.
  • the tail gas also contains a small amount of by-product CFC-12 and other gases.
  • the catalyst is significantly deactivated after 804h. . Compared with Comparative Example 4, the experimental results indicate that the ability to improve the stability and life of the catalyst is weakened when the mass content of Co 2 O 3 is 5.0%.
  • Example 1 Numbering catalyst Catalyst life (h) Example 1 1 905 Example 2 2 989 Example 3 3 956 Example 4 4 978 Example 5 5 817 Example 6 6 854 Example 7 7 2063 Example 8 8 2145

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Abstract

一种HFC-23资源化利用中减少催化剂积碳的方法，所述资源化利用采用HFC-23和卤代烃进行氟氯交换反应实现，所述氟氯交换反应的催化剂包括主体催化剂和贵金属，所述贵金属选自Pt、Pd、Ru、Au或Rh中至少一种，添加量为0.01～2wt％；在所述氟氯交换反应的过程中，通入氢气。具有催化剂稳定性好、寿命长等优点。

Description

一种HFC-23资源化利用中减少催化剂积碳的方法 技术领域
本发明涉及HFC-23资源化利用，特别涉及在HFC-23资源化利用中降低催化剂表面积碳，提高催化剂稳定性的方法。
背景技术
HFC-23(CHF 3，三氟甲烷，R23)是工业生产HFC-22(HCFC-22，二氟一氯甲烷，R22或CHClF 2)不可避免的副产物，具有较强的温室效应，其全球变暖潜值(GWP，Global Warming Potential)是CO 2的14800倍。据统计，2013年我国HFC-23的排放量占全世界排放量的68％，产生量达2万吨以上，折合CO 2年排放量达到2.96亿吨。因此，HFC-23资源化利用是实现节能减排中一个重要的课题。
目前工业上对HCFC-22生产过程中产生的副产HFC-23一般采取直接排放或者通过1200℃高温焚烧的方法处理，但直接排放会带来环境污染，而1200℃高温焚烧处理运行和设备成本较高，增加HCFC-22的生产成本。鉴于此，现有技术中对HFC-23的资源化利用采用如下手段：
美国专利US3009966A公开了在700-1090℃下三氟甲烷热解制备TFE和六氟丙烯(HFP)的方法，然而此方法产生较多的全氟异丁烯(PFIB)副产，即使以降低产率为代价在较低温度下进行也会产生不可忽略的PFIB的量，而PFIB具有极高的毒性，处理过程也比较复杂。
WO96/29296A公开了HCFC-22与HFC-23共裂解形成大分子氟代烷的方法，虽然该方法HCFC-22的转化率可达100％，但产物五氟乙烷的收率仅为60％，且产生了额外需处理的低价值副产物。
美国专利US2003/0166981公开了以金作为催化剂，在690～775℃的温度下，HFC-23与HCFC-22热解生产五氟乙烷(HFC-125)、七氟丙烷(HFC-227ea)、TFE和HFP的混合物。但该方法热解温度高，反应条件严苛。
中国专利CN104628514A公开了甲烷和三氟甲烷以一定比例通入装有催化剂的反应器，同时添加O 2，在较高温度的条件下反应生成偏氟乙烯(VDF)。但该路线同样属于裂解途径，热解温度高，反应条件严苛。
中国专利CN104628513A公开了三氟甲烷和氯仿为原料、在路易斯酸催化作用下转化成HCFC-22的方法。该方法通过分子间氟氯交换，在相对较低的温度(低于400℃)下实现了三氟甲烷的转化。但该方法采用较强的路易斯酸催化剂，催化剂稳定性差，非常容易因积碳和烧结而导致失活。
中国专利CN109748775A公开了在MgF 2、Al 2O 3、部分氟化氧化铝或AlF 3催化剂的存在下，三氟甲烷和二氯甲烷反应转化为价值更高的二氟甲烷，同时在反应阶段持续加入Cl 2、CCl 4、H 2、O 2、CO 2、O 3和氮氧化物促进气体。该方法虽然提高了催化剂的稳定性，但副产物CFC-12的选择性大大提高，达到2％～8％，产物选择性降低。
发明内容
为了解决上述技术问题，本发明提出了一种减少催化剂积碳，提高催化剂稳定性、寿命的方法。
本发明的目的是通过以下技术方案实现的：
一种HFC-23资源化利用中提高催化剂稳定性的方法，所述资源化利用采用 HFC-23和卤代烃进行氟氯交换反应实现：
Cat.
CHF 3+CHCl 3→CHClF 2+CHClF 2F
上述氟氯交换的产物包括二氟一氯甲烷(HCFC-22)和一氟二氯甲烷(HCFC-21)，发明人发现两者在催化剂表面容易发生歧化反应，造成催化剂的积碳，反应式如下：
2CHClF 2→CHF 3+CHFCl 2
2CHCl 2F→CHCl 3+CHClF 2
为了去除催化剂表面产生的积碳，故：
所述氟氯交换反应的催化剂包括主体催化剂和贵金属，所述贵金属选自Pt、Pd、Ru、Au或Rh中至少一种，添加量为0.01～2wt％；作为优选，所述贵金属为Pt或Pd，添加量为0.1～0.5wt％。
在所述氟氯交换反应的过程中，通入氢气。通入方式为：将氢气与HFC-23、卤代烃形成混合气后连续通入催化剂床层，HFC-23、卤代烃和氢气摩尔比为1:1～3:0.01～0.5，作为优选，HFC-23、卤代烃和氢气摩尔比为1:1.5～2.5:0.05～0.2。
在主体催化剂上添加贵金属，可以更有效地吸附H 2，实现原位将积碳加氢转化为CH 4。
通过贵金属的引入，可以将积碳进行转化，但并不能抑制积碳的产生。为了实现产物HCFC-22和HCFC-21在催化剂表面快速脱附，从根本上降低催化剂表面积碳，提高催化剂稳定性及寿命，故：
所述催化剂还包括金属氧化物，所述金属氧化物选自K、Na、Fe、Co、Cu、Ni、Zn或Ti中的至少一种金属氧化物，添加量为0.1～5wt％，添加方法采用现有催化剂制备的常规方法即可，如：通过与主体催化剂物理研磨，或经金属盐 溶液前驱体湿混法或浸渍法掺入再焙烧。作为优选，所述金属氧化物选自Fe、Co、Ni或Zn的金属氧化物，添加量为0.5～2wt％。
所述主体催化剂为铬、铝、镁基催化剂或铬、铝、镁负载在活性炭/石墨上的催化剂；作为优选，所述主体催化剂选自Cr 2O 3、Cr 2O 3/Al 2O 3、Cr 2O 3/AlF 3、Cr 2O 3/C、MgO、MgO/Al 2O 3、MgO/AlF 3、MgO/AlF 3、Al 2O 3或AlF 3中的至少一种。
本发明的催化剂需要进行预处理，当所述催化剂包括主体催化剂和贵金属时，完成对主体催化剂的预处理后进行贵金属的添加；当所述催化剂包括主体催化剂、贵金属和金属氧化物时，在主体催化剂上添加金属氧化物后进行预处理，预处理完成后进行贵金属的添加。具体预处理过程包括如下步骤：
(1)在1％～20％氟化氢和80％～99％氮气混合气氛下，250℃～450℃氟化处理1～6h；
(2)在氟化氢气氛下，300℃～500℃下处理2～8小时；
(3)通氮气吹扫降温。
上述氟氯交换反应中的卤代烃为氯仿或含有氯仿的混合物，氟氯交换反应条件为：HFC-23和卤代烃的摩尔配比为：1～1：3，反应温度为250～400℃，反应压力为：0.1～3bar，停留时间为4～50s。作为优选，HFC-23和卤代烃的摩尔配比为：1：1～2，反应温度为300～360℃，反应压力为：0.1～2bar，停留时间为4～12s。
与现有技术相比，本发明具有的有益效果为：
(1)日本发明通过在主体催化剂中添加贵金属，并在氟氯交换反应时，将氢气与原料气(HFC-23与卤代烃)混合后持续通入催化剂床层，促进氢气在催化剂表面的吸附，促进催化剂表面积碳原位加氢生成CH 4，从而原位消除催化剂积碳，提高催化剂稳定性和寿命。且由于反应体系中HFC-23，卤代烃(氯仿)， HCFC-22及HCFC-21本身可以作为灭火剂或制冷剂，燃烧性能差，因此利用高反应性的氢气抑制催化剂积碳对目标反应性能影响小，可以实现选择性消除积碳；
(2)本发明通过在催化剂中添加金属氧化物，加速产物HCFC-22和HCFC-21在催化剂表面的脱附，从而抑制其在催化剂表面发生歧化反应，减少了副反应产生的积碳，提高了催化剂的稳定性及寿命；
(3)本发明通过在主体催化剂中同时添加贵金属和金属氧化物，不仅可以抑制积碳的产生，还能对产生的积碳进行原位消除，发挥较好的协同作用，显著提高催化剂的稳定性，延长催化剂使用寿命.
具体实施方式
下面结合具体实施例来对本发明进行进一步说明，但并不将本发明局限于这些具体实施方式。本领域技术人员应该认识到，本发明涵盖了权利要求书范围内所可能包括的所有备选方案、改进方案和等效方案。
实施例1
催化剂的制备：对三氧化二铬催化剂(主体催化剂)进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。将氟化预处理后的催化剂倒入正己烷中搅拌分散均匀，逐滴滴加Ru纳米胶体分散液，控制Ru的负载量质量含量为0.1％，连续搅拌4h后静置，溶液上层变为透明澄清后转移入旋蒸仪中，80℃旋转蒸干，烘箱中110℃干燥过夜，马弗炉中400℃焙烧6h得到成型催化剂，记为催化剂1。
HFC-23资源化：将三氟甲烷、氯仿和氢气以1:1.5:0.2(摩尔比)通入装有50ml催化剂1的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。三氟甲烷的转化率为27.1％，HCFC-22的选择性为45.7％， HCFC-21选择性为53.1％，尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过905h后显著失活，说明负载具有加氢性能的贵金属Ru催化剂，同时通入氢气能消除积碳，实现催化剂的原位再生。
实施例2
催化剂的制备：对三氧化二铬催化剂(主体催化剂)进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。将氟化预处理后的催化剂倒入正己烷中搅拌分散均匀，逐滴滴加Pt纳米胶体分散液，控制Pt的负载量在0.1wt％，连续搅拌4h后静置，溶液上层变为透明澄清后转移入旋蒸仪中，80℃旋转蒸干，烘箱中110℃干燥过夜，马弗炉中400℃焙烧6h得到成型催化剂，记为催化剂2。
HFC-23资源化：将三氟甲烷、氯仿和氢气以1:1.5:0.2(摩尔比)通入装有50ml催化剂2的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。三氟甲烷的转化率为27.9％，HCFC-22的选择性为45.9％，HCFC-21选择性为52.9％，尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过989h后显著失活，说明负载具有加氢性能的贵金属Pt催化剂，同时通入氢气能消除积碳，实现催化剂的原位再生。
实施例3
催化剂的制备：对三氧化二铬催化剂(主体催化剂)进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。将氟化预处理后的催化剂倒入正己烷中搅拌分散均匀，逐滴滴加Pd纳米胶体分散液，控制Pd的质量负载量在0.1％，连续搅拌4h后静置，溶液上层变为透明澄清后转移入旋蒸仪 中，80℃旋转蒸干，烘箱中110℃干燥过夜，马弗炉中400℃焙烧6h得到成型催化剂，记为催化剂3。
HFC-23资源化：将三氟甲烷、氯仿和氢气以1:1.5:0.2(摩尔比)通入装有50ml催化剂3的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。三氟甲烷的转化率为26.9％，HCFC-22的选择性为43.9％，HCFC-21选择性为54.7％，尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过956h后显著失活，说明负载具有加氢性能的贵金属Pd催化剂，同时通入氢气能消除积碳，实现催化剂的原位再生。
实施例4
本实施例的操作同实施例2，区别仅在于：将实施例2的主体催化剂三氧化二铬替换为AlF 3，制备获得的催化剂记为催化剂4。
三氟甲烷的转化率为26.8％，HCFC-22的选择性为45.4％，HCFC-21选择性为53.9％，尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过978h后显著失活，说明在AlF 3主体催化剂上负载具有加氢性能的贵金属Pt催化剂，通入氢气后能原位消除积碳，实现催化剂的再生。
实施例5
本实施例的操作同实施例2，区别仅在于：将实施例2中Pt的负载量由0.1wt％降低为0.05wt％，制备获得的催化剂记为催化剂5。
三氟甲烷的转化率为27.0％，HCFC-22的选择性为45.5％，HCFC-21选择性为53.1％,尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过817h后显著失活，较实施例2结果，说明加氢贵金属催化剂负载量降至0.05wt％，原位消除积碳的能力有所下降。
实施例6
本实施例的操作同实施例2，区别仅在于：将实施例2中Pt的负载量由0.1wt％升高为1.0wt％，制备获得的催化剂记为催化剂6。
三氟甲烷的转化率为26.8％，HCFC-22的选择性为45.6％，HCFC-21选择性为53.2％,尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过854h后显著失活，较实施例2结果，说明加氢贵金属催化剂负载量升高至1.0％时，原位消除积碳的能力也有所下降。
实施例7
催化剂的制备：将三氧化二铬(主体催化剂)和三氧化二钴粉末通过研磨混合，控制Co质量含量为1.0％，获得1.0％Co/Cr 2O 3催化剂前驱体。对所述1.0％Co/Cr 2O 3催化剂前驱体进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。
将氟化预处理后的催化剂倒入正己烷中搅拌分散均匀，逐滴滴加Pt纳米胶体分散液，控制Pt的质量负载量在0.1％，连续搅拌4h后静置，溶液上层变为透明澄清后转移入旋蒸仪中，80℃旋转蒸干，烘箱中110℃干燥过夜，马弗炉中400℃焙烧6h得到成型催化剂，记为催化剂7。
HFC-23资源化：将三氟甲烷、氯仿和氢气以1:1.5:0.1(摩尔比)通入装有50ml催化剂7的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。三氟甲烷的转化率为26.7％，HCFC-22的选择性为48.6％，HCFC-21选择性为50.3％，尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过2063h后显著失活，说明三氧化二铬主体催化剂负载具有加氢性能的贵金属Pt和避免积碳反应的Co时存在协同作用，催化剂寿命高 于单一添加贵金属或单一添加金属氧化物的情形。
实施例8
催化剂的制备：将氟化铝(主体催化剂)和三氧化二钴粉末通过研磨混合，控制Co质量含量为1.0％，获得1.0％Co/AlF 3催化剂前驱体。对所述1.0％Co/AlF 3催化剂前驱体进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。
将氟化预处理后的催化剂倒入正己烷中搅拌分散均匀，逐滴滴加Pt纳米胶体分散液，控制Pt的质量负载量在0.1％，连续搅拌4h后静置，溶液上层变为透明澄清后转移入旋蒸仪中，80℃旋转蒸干，烘箱中110℃干燥过夜，马弗炉中400℃焙烧6h得到成型催化剂，记为催化剂8。
HFC-23资源化：将三氟甲烷、氯仿和氢气以1:1.5:0.2(摩尔比)通入装有50ml催化剂8的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。三氟甲烷的转化率为26.7％，HCFC-22的选择性为44.6％，HCFC-21选择性为54.3％，尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂经过2145h后显著失活，说明氟化铝主体催化剂负载具有加氢性能的贵金属Pt和避免积碳反应的Co时存在协同作用，催化剂寿命高于单一添加贵金属或单一添加金属氧化物的情形。
对比例1
对三氧化二铬催化剂进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。预处理后催化剂记为B1。
HFC-23资源化：将三氟甲烷和氯仿以1:1.5(摩尔比)通入装有50ml催化 剂B1的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。三氟甲烷的转化率为25.6％，HCFC-22的选择性为44.4％，HCFC-21选择性为55.2％，尾气中还包含少量的副产CFC-12等气体。催化剂经过340h后显著失活，取出催化剂发现明显变黑，积碳严重。
对比例2
本对比例的操作同对比例1，区别仅在于：将催化剂三氧化二铬替换为AlF 3，预处理后的催化剂记为B2。
三氟甲烷的转化率为25.8％，HCFC-22的选择性为44.2％，HCFC-21选择性为54.9％，尾气中还包含少量的副产CFC-12等气体。催化剂经过395h后显著失活，取出催化剂发现明显变黑，积碳严重。
对比例3
催化剂的制备：对三氧化二铬催化剂(主体催化剂)进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。将氟化预处理后的催化剂倒入正己烷中搅拌分散均匀，逐滴滴加Ag纳米胶体分散液，控制Ag的负载量在0.1wt％，连续搅拌4h后静置，溶液上层变为透明澄清后转移入旋蒸仪中，80℃旋转蒸干，烘箱中110℃干燥过夜，马弗炉中400℃焙烧6h得到成型催化剂，记为催化剂B3。
HFC-23资源化：将三氟甲烷、氯仿和氢气以1:1.5:0.2(摩尔比)通入装有50ml催化剂2的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。
三氟甲烷的转化率为26.3％，HCFC-22的选择性为45.6％，HCFC-21选择性为53.2％,尾气中还包含少量的副产CFC-12等气体和痕量的甲烷等气体。催化剂 经过321h后显著失活，说明主体催化剂上负载贵金属Ag，通入氢气并未能实现催化剂的原位再生。
对比例4
催化剂制备：将三氧化二铬和三氧化二钴粉末通过研磨混合，控制Co质量含量为1.0％，获得1.0％Co/Cr 2O 3催化剂前驱体，对所述1.0％Co/Cr 2O 3催化剂前驱体进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。预处理后的催化剂记为B4。
HFC-23资源化：将三氟甲烷和氯仿以1:1.5(摩尔比)通入装有50ml催化剂B4的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。
三氟甲烷的转化率为26.6％，HCFC-22的选择性为44.3％，HCFC-21选择性为54.7％，尾气中还包含少量的副产CFC-12等气体。催化剂经过973h后显著失活。实验结果说明添加Co 2O 3后能有效的提高催化剂的稳定性和寿命。
对比例5
催化剂制备：将三氧化二铬和三氧化二铁粉末通过研磨混合，控制Fe质量含量为1.0％，获得1.0％Fe/Cr 2O 3催化剂的前驱体。对所述1.0％Fe/Cr 2O 3催化剂前驱体进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。预处理后的催化剂记为B5。
HFC-23资源化：将三氟甲烷和氯仿以1:1.5(摩尔比)通入装有50ml催化剂B5的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。
三氟甲烷的转化率为26.3％，HCFC-22的选择性为44.7％，HCFC-21选择性为54.4％，尾气中还包含少量的副产CFC-12等气体，催化剂经过861h后显著失活。实验结果说明添加Fe 2O 3后能有效的提高催化剂的稳定性和寿命。
对比例6
催化剂制备：将三氧化二铬和三氧化二镍粉末通过研磨混合，控制Ni质量含量为1.0％，获得1.0％Ni/Cr 2O 3催化剂前驱体。对所述1.0％Ni/Cr 2O 3催化剂前驱体进行预处理，预处理过程包括：1)10％氟化氢和90％氮气混合气氛下，250℃氟化处理2小时；2)氟化氢气氛下，300℃处理5小时；3)通氮气吹扫降温。预处理后的催化剂记为B6。
HFC-23资源化：将三氟甲烷和氯仿以1:1.5(摩尔比)通入装有50ml催化剂B6的反应器，反应温度310℃，反应压力1bar，停留时间5s，进行氟氯交换反应。
三氟甲烷的转化率为25.3％，HCFC-22的选择性为43.7％，HCFC-21选择性为55.4％，尾气中还包含少量的副产CFC-12等气体，催化剂经过758h后显著失活。实验结果说明添加Ni 2O 3后能有效的提高催化剂的稳定性和寿命。
对比例7
本对比例的操作同对比例4，区别仅在于：将催化剂三氧化二铬替换为氟化铝，预处理后的催化剂记为B7。
三氟甲烷的转化率为26.3％，HCFC-22的选择性为44.1％，HCFC-21选择性为54.9％，尾气中还包含少量的副产CFC-12等气体，催化剂经过965h后显著失活。实验结果说明在主体催化剂AlF 3上添加Co 2O 3后能有效的提高催化剂的稳定性和寿命。
对比例8
本对比例的操作同对比例4，区别仅在于：将对比例4中Co的质量含量由1.0％降至0.1％，制备获得的催化剂记为催化剂B8。
三氟甲烷的转化率为26.4％，HCFC-22的选择性为44.1％，HCFC-21选择性为54.9％，尾气中还包含少量的副产CFC-12等气体，催化剂经过654h后显著失活。实验结果较对比例4，说明添加Co 2O 3质量含量为0.1％时提高催化剂的稳定性和寿命的能力减弱。
对比例9
本对比例的操作同对比例4，区别仅在于：将对比例4中Co的质量含量由0.1％升高至5.0％，制备获得的催化剂记为催化剂B9。
三氟甲烷的转化率为26.3％，HCFC-22的选择性为44.4％，HCFC-21选择性为54.3％，尾气中还包含少量的副产CFC-12等气体，催化剂经过804h后显著失活。实验结果较对比例4，说明添加Co 2O 3质量含量为5.0％时提高催化剂的稳定性和寿命的能力减弱。
表1不同催化剂体系的催化效果
编号 催化剂 催化剂寿命(h)
实施例1 1 905
实施例2 2 989
实施例3 3 956
实施例4 4 978
实施例5 5 817
实施例6 6 854
实施例7 7 2063
实施例8 8 2145
对比例1 B1 340
对比例2 B2 395
对比例3 B3 321
对比例4 B4 973
对比例5 B5 861
对比例6 B6 758
对比例7 B7 965
对比例8 B8 654
对比例9 B9 804

Claims (10)

  1. 一种HFC-23资源化利用中减少催化剂积碳的方法，所述资源化利用采用HFC-23和卤代烃进行氟氯交换反应实现，其特征在于：所述氟氯交换反应的催化剂包括主体催化剂和贵金属，所述贵金属选自Pt、Pd、Ru、Au或Rh中至少一种，添加量为0.01～2wt％；
    在所述氟氯交换反应的过程中，通入氢气。
  2. 根据权利要求1所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：所述贵金属为Pt或Pd，添加量为0.1～0.5wt％。
  3. 根据权利要求1或2所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：所述催化剂还包括金属氧化物，所述金属氧化物选自K、Na、Fe、Co、Cu、Ni、Zn或Ti中的至少一种金属氧化物，添加量为0.1～5wt％。
  4. 根据权利要求3所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：所述金属氧化物选自Fe、Co、Ni或Zn的金属氧化物，添加量为0.5～2wt％。
  5. 根据权利要求1-4任一所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：将氢气与HFC-23、卤代烃形成混合气后通入，HFC-23、卤代烃和氢气摩尔比为1:1～3:0.01～0.5。
  6. 根据权利要求5所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：氢气连续通入催化剂床层。
  7. 根据权利要求3或4所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：对所述催化剂进行预处理，预处理过程包括如下步骤：
    (1)在1％～20％氟化氢和80％～99％氮气混合气氛下，250℃～450℃氟化 处理1～6h；
    (2)在氟化氢气氛下，300℃～500℃下处理2～8小时；
    (3)通氮气吹扫降温。
  8. 根据权利要求1所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：所述卤代烃为氯仿或含有氯仿的混合物。
  9. 根据权利要求8所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：所述主体催化剂为铬、铝、镁基催化剂或铬、铝、镁负载在活性炭/石墨上的催化剂。
  10. 根据权利要求1-9任一所述的HFC-23资源化利用中减少催化剂积碳的方法，其特征在于：所述氟氯交换反应条件为：HFC-23和卤代烃的摩尔配比为1～1：3，反应温度为250～400℃，反应压力为：0.1～3bar，停留时间为4～50s。
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