Fluorination catalyst as well as preparation method and application thereof

Abstract

The invention relates to a fluorination catalyst and a preparation method and application thereof.The preparation method comprises the following steps that doping is conducted, specifically, Cr elements, Zn elements, Ni elements, La elements and Ce elements are added into an activated carbon carrier through an impregnation method or a coprecipitation method, doped activated carbon is obtained, calcining is conducted, specifically, the doped activated carbon is dried in the N2 atmosphere and then calcined at the temperature of 150-350 DEG C, and calcined activated carbon is obtained; and activation: carrying out a fluorination reaction on the calcined activated carbon and anhydrous hydrogen fluoride to obtain the fluorination catalyst. The catalyst can efficiently catalyze chloro-acyl chloride to generate fluoro-acyl halide, by-products are few, the catalytic activity is high, the stability of the catalyst is high, and industrial production is facilitated.

Description

Technical Field

[0001] The present application relates to the field of fluorine chemical industry, and in particular to a fluorination catalyst and a preparation method and use thereof. Background Art

[0002] Fluoroacetyl halides, as an important chemical intermediate, are often prepared by the fluorination of chloroacyl chlorides. In the process of fluorination to generate fluoroacyl halides, it is very important to find a suitable catalyst with high catalytic activity and good catalytic stability.

[0003] CN 114105766A discloses the use of HF fluorination to prepare trifluoroacetyl fluoride. The preparation process of the chromium complex catalyst is complicated, and the catalyst preparation process requires pulping, water washing, recrystallization and other operations to remove residual chloride ions, and a large amount of wastewater is generated during the catalyst preparation process.

[0004]

[0005] CN 102471207 A discloses the use of a chromium oxide-nickel (or magnesium) based catalyst to prepare trifluoroacetyl fluoride by HF fluorination. The chromium oxide-nickel (or magnesium) based catalyst provides limited Lewis acid centers and performs poorly in terms of catalytic effect and catalyst life. Summary of the invention

[0006] In view of the above problems, the present application provides a fluorination catalyst with activated carbon as a carrier and doped with Cr2O3, Zn, Ni, La and Ce elements, which can efficiently catalyze chloroacyl chlorides to generate fluoroacyl halides, has few by-products, high catalytic activity, high catalyst stability, and is conducive to industrial production.

[0007] The present invention first provides a method for preparing a fluorination catalyst, comprising the following steps:

[0008] Doping: Cr, Zn, Ni, La and Ce are added to the activated carbon carrier by impregnation or coprecipitation to obtain doped activated carbon.

[0009] Calcination: drying the doped activated carbon in a N2 atmosphere and then calcining the doped activated carbon at 150-350°C to obtain calcined activated carbon;

[0010] Activation: subjecting the calcined activated carbon to a fluorination reaction with anhydrous hydrogen fluoride to obtain the fluorination catalyst.

[0011] Different from the prior art, the above technical solution provides a new fluorination catalyst, which uses activated carbon as a carrier and is doped with Cr2O3, Zn, Ni, La and Ce. The electronic structure of La and Ce is special, with abundant 3d and 4f electrons, and a single electron in 5d, which makes the catalyst have a higher catalytic activity in catalysis.

[0012] Furthermore, in the doping step, the impregnation method includes the following steps:

[0013] 1) Put Cr2O3, Zn salt, Ni salt, La salt and Ce salt into water and mix them evenly to obtain an impregnation solution;

[0014] 2) The activated carbon is put into the impregnation solution for 5-48 hours, and the doped activated carbon is obtained after drying.

[0015] Furthermore, the impregnation method also includes multiple impregnations, that is, after the activated carbon is impregnated for the first time, it is dried and then immersed in the impregnation liquid for a second or third time, so that the content of each active metal on the activated carbon is increased.

[0016] Furthermore, in the impregnation solution, the concentrations of Zn salt, Ni salt, La salt and Ce salt are not less than 0.5 ml / L.

[0017] Furthermore, in the doping step, the coprecipitation method comprises the following steps:

[0018] a) adding Cr salt, Zn salt, Ni salt, La salt and Ce salt into water and mixing them evenly to obtain a metal salt aqueous solution;

[0019] b) putting the activated carbon into the metal salt aqueous solution, then adding a precipitant to make the pH of the solution greater than 10, aging, washing and drying to obtain the doped activated carbon.

[0020] Furthermore, in the aqueous metal salt solution, the concentrations of the Cr salt, Zn salt, Ni salt, La salt and Ce salt are not less than 0.5 ml / L.

[0021] Furthermore, the Cr salt, Zn salt, Ni salt, La salt and Ce salt are water-soluble salts, including hydrochlorides, sulfates, nitrates or acetates.

[0022] Further, the precipitant includes ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate. In some embodiments, ammonia gas can also be introduced into the metal salt aqueous solution to also play a role in precipitation.

[0023] Furthermore, in the doping step, based on the molar amount of the added Ce element, the added amounts of the Zn element, the Ni element, the La element and the Ce element are each 0.1%-10%.

[0024] Furthermore, in the activation step, the reaction temperature of the fluorination reaction is 150-450° C., and the reaction time is 3-24 hours.

[0025] The present invention also provides a fluorination catalyst, which is prepared by the above-mentioned preparation method.

[0026] Furthermore, taking the mass of the fluorination catalyst as the reference mass, the total content of Cr2O3, Zn element, Ni element, La element and Ce element is 10-50wt%.

[0027] The present invention also provides use of the fluorination catalyst in catalyzing chloroacyl chloride to generate fluoroacyl halide.

[0028] When chloroacetyl chloride contacts the fluorination catalyst with anhydrous hydrofluoric acid, a fluorination reaction can be rapidly initiated to generate fluoroacetyl halide. The chloroacetyl chloride includes dichloroacetyl chloride and trichloroacetyl chloride.

[0029] Different from the prior art, the novel fluorination catalyst prepared by the above technical solution uses activated carbon as a carrier and is doped with Cr2O3, Zn, Ni, La and Ce. The electronic structure of La and Ce is special, with abundant 3d and 4f electrons, and a single electron in 5d, which makes the catalyst have a high catalytic activity in catalysis and can quickly catalyze the fluorination reaction.

[0030] The above-mentioned records related to the invention content are only an overview of the technical solution of the present application. In order to enable ordinary technicians in the field to more clearly understand the technical solution of the present application, and then implement it according to the written contents of the specification, and to make the above-mentioned purpose and other purposes, features and advantages of the present application easier to understand, the specific implementation methods of the present application are explained below. DETAILED DESCRIPTION

[0031] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments.

[0032] In order to explain in detail the possible application scenarios, technical principles, specific schemes that can be implemented, and the purposes and effects that can be achieved, the following is a detailed description in conjunction with the specific embodiments listed. The embodiments described herein are only used to more clearly illustrate the technical solutions of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0033] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0034] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0035] In the description of this application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in an "or" logical relationship.

[0036] In the present application, terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship of quantity, priority or sequence between these entities or operations.

[0037] Without further limitations, in this application, the words "include", "comprises", "has" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0038] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than", "less than", "exceed" and the like are understood to exclude the number itself; expressions such as "above", "below", "within" and the like are understood to include the number itself. In addition, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups", "multiple times", etc., unless otherwise clearly and specifically limited.

[0039] The present invention first provides a method for preparing a fluorination catalyst, comprising the following steps:

[0040] Doping: Cr, Zn, Ni, La and Ce are added to the activated carbon carrier by impregnation or coprecipitation to obtain doped activated carbon.

[0041] Calcination: drying the doped activated carbon in air or oxygen atmosphere, and then calcining at 150-350° C. to obtain calcined activated carbon;

[0042] Activation: subjecting the calcined activated carbon to a fluorination reaction with anhydrous hydrogen fluoride to obtain the fluorination catalyst.

[0043] Different from the prior art, the above technical solution provides a new fluorination catalyst, which uses activated carbon as a carrier and is doped with Cr2O3, Zn, Ni, La and Ce. The electronic structure of La and Ce is special, with abundant 3d electrons and 4f electrons, and a single electron in 5d, which makes the catalyst containing La and Ce elements have higher catalytic activity in catalysis.

[0044] Furthermore, in the doping step, the impregnation method includes the following steps:

[0045] 1) Put Cr2O3, Zn salt, Ni salt, La salt and Ce salt into water and mix them evenly to obtain an impregnation solution;

[0046] 2) The activated carbon is put into the impregnation solution for 5-48 hours, and the doped activated carbon is obtained after drying.

[0047] Furthermore, the impregnation method also includes multiple impregnations, that is, after the activated carbon is impregnated for the first time, it is dried and then immersed in the impregnation liquid for a second or third time, so that the content of each active metal on the activated carbon is increased.

[0048] Furthermore, in the impregnation solution, the concentrations of Zn salt, Ni salt, La salt and Ce salt are not less than 0.5 ml / L. When the metal salts in the impregnation solution reach a certain concentration, a better impregnation effect can be ensured, and the activated carbon can adsorb more metal elements.

[0049] Furthermore, in the doping step, the coprecipitation method comprises the following steps:

[0050] a) adding Cr salt, Zn salt, Ni salt, La salt and Ce salt into water and mixing them evenly to obtain a metal salt aqueous solution;

[0051] b) putting the activated carbon into the metal salt aqueous solution, then adding a precipitant to make the pH of the solution greater than 10, aging, washing and drying to obtain the doped activated carbon.

[0052] Furthermore, in the aqueous metal salt solution, the concentrations of the Cr salt, Zn salt, Ni salt, La salt and Ce salt are not less than 0.5 ml / L.

[0053] Furthermore, the Cr salt, Zn salt, Ni salt, La salt and Ce salt are water-soluble salts, including hydrochlorides, sulfates, nitrates or acetates.

[0054] Further, the precipitant includes ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate. In some embodiments, ammonia gas can also be introduced into the metal salt aqueous solution to also play a role in precipitation.

[0055] Furthermore, in the doping step, based on the molar amount of the added Ce element, the added amounts of the Zn element, the Ni element, the La element and the Ce element are each 0.1%-10%.

[0056] Furthermore, in the activation step, the reaction temperature of the fluorination reaction is 150-450° C., and the reaction time is 3-24 hours.

[0057] The present invention also provides a fluorination catalyst, which is prepared by the above-mentioned preparation method.

[0058] Furthermore, taking the mass of the fluorination catalyst as the reference mass, the total content of Cr2O3, Zn element, Ni element, La element and Ce element is 10-50wt%.

[0059] The present invention also provides use of the fluorination catalyst in catalyzing chloroacyl chloride to generate fluoroacyl halide.

[0060] When chloroacetyl chloride contacts the fluorination catalyst with anhydrous hydrofluoric acid, a fluorination reaction can be rapidly initiated to generate fluoroacetyl halide. The chloroacetyl chloride includes dichloroacetyl chloride and trichloroacetyl chloride.

[0061] Different from the prior art, the novel fluorination catalyst prepared by the above technical solution uses activated carbon as a carrier and is doped with Cr2O3, Zn, Ni, La and Ce. The electronic structure of La and Ce is special, with abundant 3d and 4f electrons, and a single electron in 5d, which makes the catalyst have a high catalytic activity in catalysis and can quickly catalyze the fluorination reaction.

[0062] In this embodiment, the doped activated carbon is ground and pressed into a fixed bed reactor before calcination, and then calcination and activation steps are performed. Subsequently, chloroacyl chloride and hydrogen are directly introduced into the fixed bed reactor to generate fluoroacyl halide.

[0063] Wherein, if the chloroacetyl chloride is dichloroacetyl chloride, the generated fluoroacetyl halide is difluoroacetyl chloride and / or trifluoroacetyl chloride. If the chloroacetyl chloride is trichloroacetyl chloride, the generated fluoroacetyl halide is difluoroacetyl fluoride and / or trifluoroacetyl fluoride.

[0064] Examples 1-5

[0065] Doping: Cr2O3, Zn, Ni, La and Ce are added to the activated carbon carrier by an impregnation method to obtain doped activated carbon; wherein the addition amounts of Cr2O3, Zn, Ni, La and Ce in different embodiments are shown in Table 1;

[0066] 1) Put Cr(NO3)3, ZnCl2, NiCl2, La(NO3)3 and Ce(NO3)3 into water and mix them evenly to obtain an impregnation solution; wherein the concentrations of Cr, Zn, Ni, La and Ce are not less than 0.5 ml / L

[0067] 2) 75 g of activated carbon was put into the impregnation solution for 24 h, and then dried at 100° C. to obtain the doped activated carbon.

[0068] Calcination: grinding and pressing the doped activated carbon and then loading it into a fixed bed reactor, drying it in air or oxygen atmosphere for 12 hours, and then calcining it at 350° C. to obtain calcined activated carbon;

[0069] Activation: Anhydrous HF is introduced into a fixed bed reactor, and the calcined activated carbon is subjected to a fluorination reaction with anhydrous hydrogen fluoride at a fluorination temperature of 350° C. for a fluorination time of 12 hours to obtain the fluorination catalyst. The total content of Cr2O3, Zn, Ni, La and Ce in the fluorination catalyst is 25wt%. Comparative Example 1:

[0070] The difference between the control example and Example 1 is that in the doping step, only Cr(NO3)3 is added; and the Cr2O3 content in the finally obtained fluorination catalyst is 25wt%.

[0071] Trichloroacetyl chloride and anhydrous HF were continuously introduced into the fixed bed reactor containing the fluorination catalyst prepared in Examples 1-5 and Comparative Example 1, and the molar ratio of trichloroacetyl chloride to anhydrous HF was 1:20; the contact time between the reactant and the catalyst was 120 seconds, and the temperature was raised to 300° C. for fluorination reaction to obtain a trifluoroacetyl halide product. After the fluorination reaction was completed, the raw material conversion rate and product selectivity were tested, and the results are shown in Table 1.

[0072] Table 1 Process parameters of Examples 1-5 and conversion rate and selectivity of fluorination reaction

[0073]

[0074] Examples 6-10

[0075] Doping: Cr2O3, Zn, Ni, La and Ce are added to the activated carbon carrier by coprecipitation method to obtain doped activated carbon; wherein the addition amounts of Cr2O3, Zn, Ni, La and Ce in different embodiments are shown in Table 2;

[0076] a) Cr(NO3)3, Zn(NO3)2, Ni(NO3)2, LaCl3 and CeCl3 are added into water and mixed evenly to obtain a metal salt aqueous solution; the concentration of the Cr salt, Zn salt, Ni salt, La salt and Ce salt is not less than 0.5 ml / L. b) 90 g of activated carbon is added into the metal salt aqueous solution, and then ammonia water is added dropwise to make the pH of the solution greater than 10, and after aging for 24 hours, the solution is filtered, washed until the pH of the washing solution is neutral, and dried at 100°C to obtain the doped activated carbon.

[0077] Calcination: grinding and pressing the doped activated carbon and then loading it into a fixed bed reactor, drying it in air or oxygen atmosphere for 12 hours, and calcining it at 150° C. to obtain calcined activated carbon;

[0078] Activation: Anhydrous HF is introduced into a fixed bed reactor, and the calcined activated carbon is subjected to a fluorination reaction with anhydrous hydrogen fluoride at a fluorination temperature of 350° C. for a fluorination time of 12 hours to obtain the fluorination catalyst. The total content of Cr2O3, Zn, Ni, La and Ce in the fluorination catalyst is 10wt%.

[0079] Comparative Example 2:

[0080] The difference between Control Example 2 and Example 6 is that, in the doping step, only Cr(NO3)3 is added; and the Cr2O3 content in the finally obtained fluorination catalyst is 10wt%.

[0081] Trichloroacetyl chloride and anhydrous HF were continuously introduced into the fixed bed reactor containing the fluorination catalyst prepared in Examples 6-10 and Comparative Example 2, and the molar ratio of trichloroacetyl chloride to anhydrous HF was 1:20; the contact time between the reactant and the catalyst was 120 seconds, and the fluorination reaction was carried out at 150° C. to obtain a trichloroacetyl halide product. After the fluorination reaction was completed, the raw material conversion rate of trichloroacetyl chloride and the product selectivity were tested, and the results are shown in Table 2.

[0082] Table 2 Process parameters of Examples 6-10 and fluorination reaction conversion rate and selectivity

[0083]

[0084] Examples 11-15

[0085] Doping: Cr2O3, Zn, Ni, La and Ce are added to the activated carbon carrier by coprecipitation method to obtain doped activated carbon; wherein the addition amounts of Cr2O3, Zn, Ni, La and Ce in different embodiments are shown in Table 3;

[0086] b) Cr(NO3)3, Zn(NO3)2, Ni(NO3)2, LaCl3 and CeCl3 are added into water and mixed evenly to obtain a metal salt aqueous solution; the concentration of the Cr salt, Zn salt, Ni salt, La salt and Ce salt is not less than 0.5 ml / L. b) 90 g of activated carbon is added into the metal salt aqueous solution, and then ammonia water is added dropwise to make the pH of the solution>10, and after aging for 24 hours, the solution is filtered, washed until the pH of the washing solution is neutral, and dried at 100°C to obtain the doped activated carbon.

[0087] Calcination: grinding and pressing the doped activated carbon and then loading it into a fixed bed reactor, drying it in air or oxygen atmosphere for 2 hours, and calcining it at 150° C. to obtain calcined activated carbon;

[0088] Activation: Anhydrous HF is introduced into a fixed bed reactor, and the calcined activated carbon is subjected to a fluorination reaction with anhydrous hydrogen fluoride at a fluorination temperature of 350° C. for a fluorination time of 12 hours to obtain the fluorination catalyst. The total content of Cr2O3, Zn, Ni, La and Ce in the fluorination catalyst is 50wt%.

[0089] Comparative Example 3:

[0090] The difference between Control Example 3 and Example 6 is that, in the doping step, only Cr(NO3)3 is added; and the Cr2O3 content in the finally obtained fluorination catalyst is 50wt%.

[0091] Dichloroacetyl chloride and anhydrous HF were continuously introduced into the fixed bed reactor containing the fluorination catalyst prepared in Examples 11-15 and Comparative Example 3, and the molar ratio of dichloroacetyl chloride to anhydrous HF was 1:20; the contact time between the reactant and the catalyst was 120 seconds, and the fluorination reaction was carried out at 150° C. to obtain a dichloroacetyl halide product. After the fluorination reaction was completed, the raw material conversion rate of dichloroacetyl chloride and the product selectivity were tested, and the results are shown in Table 3.

[0092] Table 3 Process parameters of Examples 11-15 and fluorination reaction conversion rate and selectivity

[0093]

[0094] It can be seen from Examples 1-15 and Comparative Examples 1-3 that the catalyst with activated carbon as carrier and doped with Cr2O3, Zn, Ni, La and Ce has higher catalytic activity in catalysis than the catalyst simply doped with Cr2O3, reduces side reactions and by-products, and increases both the raw material conversion rate and product selectivity.

[0095] Finally, it should be noted that although the above embodiments have been described in the text of the specification of this application, this does not limit the scope of patent protection of this application. All technical solutions generated by replacing or modifying equivalent structures or equivalent processes based on the essential concept of this application using the contents recorded in the text of the specification of this application, as well as directly or indirectly implementing the technical solutions of the above embodiments in other related technical fields, are included in the scope of patent protection of this application.

Claims

1. A method for preparing a fluorination catalyst, characterized in that: The following steps are involved: Doping: Cr, Zn, Ni, La and Ce are added to the activated carbon carrier by impregnation or coprecipitation to obtain doped activated carbon. Calcination: drying the doped activated carbon in air or oxygen atmosphere, and then calcining at 150-350° C. to obtain calcined activated carbon; Activation: subjecting the calcined activated carbon to a fluorination reaction with anhydrous hydrogen fluoride to obtain the fluorination catalyst.

2. The preparation method according to claim 1, characterized in that: In the doping step, the impregnation method comprises the following steps: 1) Put Cr2O3, Zn salt, Ni salt, La salt and Ce salt into water and mix them evenly to obtain an impregnation solution; 2) The activated carbon is put into the impregnation solution for 5-48 hours, and the doped activated carbon is obtained after drying.

3. The preparation method according to claim 1, characterized in that: In the doping step, the coprecipitation method comprises the following steps: a) adding Cr salt, Zn salt, Ni salt, La salt and Ce salt into water and mixing them evenly to obtain a metal salt aqueous solution; b) putting the activated carbon into the metal salt aqueous solution, then dropping a precipitant to make the pH of the metal salt aqueous solution greater than 10, and obtaining the doped activated carbon after aging, washing and drying.

4. The preparation method according to claim 2 or 3, characterized in that: The Cr salt, Zn salt, Ni salt, La salt and Ce salt are water-soluble salts, and the water-soluble salts include hydrochloride, sulfate, nitrate or acetate.

5. The preparation method according to claim 3, characterized in that: The precipitating agent includes ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

6. The preparation method according to claim 1, characterized in that: In the doping step, based on the molar amount of the added Cr element, the added amounts of the Zn element, the Ni element, the La element and the Ce element are each 0.1%-10%.

7. The preparation method according to claim 1, characterized in that: In the activation step, the reaction temperature of the fluorination reaction is 150-450° C., and the reaction time is 3-24 hours.

8. A fluorination catalyst, characterized in that The fluorination catalyst is prepared by the preparation method according to any one of claims 1 to 7.

9. The fluorination catalyst according to claim 8, characterized in that Taking the mass of the fluorination catalyst as the reference mass, the total content of Cr2O3, Zn element, Ni element, La element and Ce element is 10-50wt%.

10. Use of the fluorination catalyst according to claim 8 or 9 in catalyzing the generation of fluoroacyl halides from chloroacyl chlorides.

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