阅读说明：本技术 一种制备全卤代乙烯的催化剂及其制备方法和应用 (Catalyst for preparing perhalogenated ethylene and preparation method and application thereof ) 是由 马超峰 石能富 李玲 刘武灿 金佳敏 于 2020-12-10 设计创作，主要内容包括：本发明涉及一种用于催化生产全卤代乙烯的催化剂,至少包括以VIII族和/或VIB族和/或IIB族金属的氮化物和/或碳化物为催化剂活性组分,其制备方法包括步骤(1)制备金属氧化物前驱体；步骤(2)程序升温还原氮化和/或碳化；步骤(3)钝化,即制得该催化剂。(The invention relates to a catalyst for catalyzing and producing perhalogenated ethylene, which at least comprises nitrides and/or carbides of VIII group and/or VIB group and/or IIB group metals as catalyst active components, and the preparation method comprises the steps of (1) preparing a metal oxide precursor; step (2), temperature programming, reduction, nitridation and/or carbonization; and (3) passivating to obtain the catalyst.)

1. A catalyst for the catalytic production of perhalogenated ethylene characterized in that: at least comprises nitrides and/or carbides of VIII group and/or VIB group and/or IIB group metals as catalyst active components;

at least one of the feedstocks is a perhaloethane corresponding to the formula: CF (compact flash)_aCl_b-CF_dCl_fWherein a is 0 to 3, b is 1 to 3, and a + b is 3; d is 0 to 3, f is 1 to 3, and d + f is 3; and b + f is 2-6; the perhaloethane is 1, 2-dichlorotetrafluoroethane (fluorocarbon 114) or 1,1, 2-trichloro-1, 2, 2-trifluoroethane;

at least one product is a perhalogenated ethylene corresponding to the formula: CF (compact flash)_mCl_n＝CF_xCl_yWherein m is 0-2, n is 0-2, and m + n is 2; and x is 0-2, y is 0-2, and x + y is 2; the product is chlorotrifluoroethylene.

2. A catalyst for the catalytic production of perhalogenated ethylene according to claim 1, characterized in that: the catalyst also comprises a carrier, and the content of the active component is 0.5-30 wt%.

3. The catalyst for the catalytic production of perhalogenated ethylene according to claim 1 or 2, characterized in that: the catalyst active component comprises at least one metal nitride or metal carbide.

4. The catalyst for the catalytic production of perhalogenated ethylene according to claim 3, characterized in that: the catalyst active component at least comprises nitrogen/carbide, wherein the nitrogen/carbide is selected from nitrogen/cobalt carbide, nitrogen/molybdenum carbide, nitrogen/iron carbide, nitrogen/zinc carbide, nitrogen/tungsten carbide or nitrogen/nickel carbide; wherein nitrogen/carbide means a metal compound containing both nitride and carbide of a metal element.

5. The catalyst for the catalytic production of perhalogenated ethylene according to any one of claims 1 to 4, characterized in that: the catalyst also comprises an auxiliary agent which is a nitride and/or carbide of a metal in VIII group or IIB group, which is different from the active component.

6. The catalyst for the catalytic production of perhalogenated ethylene according to any of the previous claims, characterized in that: the preparation method comprises the steps of (1) preparing a metal oxide precursor; step (2), temperature programming, reduction, nitridation and/or carbonization; and (3) passivating to obtain the catalyst.

7. A catalyst for the catalytic production of perhalogenated ethylene according to claim 6, characterized in that: weighing a certain amount of salt containing active metal components, roasting at high temperature for 2-6h in air atmosphere, tabletting, and screening to obtain precursor metal oxide; or soaking the carrier in a first metal salt solution with a certain concentration, standing overnight at room temperature, drying for 2-10h at 80-160 ℃ in the air atmosphere, roasting for 2-6h in the air atmosphere, cooling, drying to obtain a precursor metal oxide, soaking in an auxiliary agent salt solution after cooling and drying, and obtaining the precursor metal oxide by the same treatment mode as the first soaking.

8. The catalyst for the catalytic production of perhalogenated ethylene according to claim 6 or 7, characterized in that: and (2) performing temperature programming reduction nitridation and/or carbonization on the precursor metal oxide in a vacuum heating furnace, vacuumizing and then introducing nitrogen for purging before nitridation and/or carbonization, and then introducing reducing gas for nitridation and/or carbonization.

9. The catalyst for the catalytic production of perhalogenated ethylene according to claim 8, characterized in that: the reducing gas is one or more of ammonia gas, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, ethylenediamine, monoethanolamine and diethanolamine.

10. The process for the preparation of a catalyst for the catalytic production of perhalogenated ethylene according to any of the preceding claims, characterized in that the preparation process comprises the steps of (1) preparing a metal oxide precursor; step (2), temperature programming, reduction, nitridation and/or carbonization; and (3) passivating to obtain the catalyst.

Technical Field

The application relates to a catalyst and a preparation method thereof, in particular to a catalyst for preparing perhalogenated ethylene and a preparation method thereof.

Background

CTFE is an important commercial monomer in the production of fluoropolymers, and can be used for preparing a series of fluorine coatings, fluorine resins, fluorine rubbers, fluorine-chlorine lubricating oil and the like. These fluorine-containing materials have excellent chemical inertness and weather resistance, and have wide applications in the fields of advanced technologies, military aerospace, electronic industry and the like. Various methods have been used to prepare CTFE, and the existing production processes mainly include: trifluoro trichloroethane metal zinc powder reduction dechlorination method, trifluoro trichloroethane catalytic hydrogenation dechlorination method, trifluoro trichloroethane catalytic dechlorination method under the participation of ethylene and oxygen, trifluoro trichloroethane electrochemical reduction method, tetrafluoro monochloroethane cracking method and the like.

EP0459463A discloses the influence of the properties of the support on the preparation of chlorotrifluoroethylene by catalytic hydrogenation, the conversion of chlorotrifluoroethane being below 50% when using alumina as support, which compares Pd-Hg/Al₂O₃The catalyst used in the former case was 1.3g, Pd loading was 0.5% and conversion was 54.7% and the catalyst used in the latter case was 0.6g, Pd loading was 2% and conversion was 63.9% of Pd-Hg/C activity.

US5089454A discloses that the material such as active carbon, alumina, titanium oxide, etc. is used as carrier, one or more of alkali metal and alkaline earth metal salt is used as auxiliary agent, VIII group metal is used as catalyst active component, when the reaction temperature is 200-300 ℃, the conversion rate of chlorotrifluoroethylene is above 40%.

CN1460549A discloses a catalyst for preparing trifluorochloroethylene and trifluoroethylene by catalytic hydrogenation and dechlorination of 1,1, 2-trifluoro-2, 2, 1-trichloroethane, which is characterized in that noble metal palladium and metal copper are used as main active components, alkali metal lithium and rare earth metal or metal lanthanum are added as modifying additives, and coconut shell activated carbon is used as a carrier; the dosage of the noble metal palladium is 0.5 to 0.4 percent of the total weight of the catalyst; the dosage of the adopted metal copper is 1 to 12 percent of the total weight of the catalyst; the dosage of the adopted metal lithium is 0.2 to 2 percent of the total weight of the catalyst; the dosage of the rare earth metal or the metal lanthanum is 0.5 to 4 percent of the total weight of the catalyst. The conversion rate of raw materials can reach 100 percent, and the highest CTFE selectivity can reach 84.7 percent.

CN105457651A discloses a hydrodechlorination catalyst, which consists of a main catalyst, an auxiliary agent and a carrier; the main catalyst is Pd and Cu; the auxiliary agent is selected from one, two or more than three of Mg, Ca, Ba, Co, Mo, Ni, Sm and Ce; the main catalyst and the auxiliary agent are loaded on the activated carbon carrier. The preparation method comprises the following steps: adding activated carbon into an acid or alkali solution, performing water bath reflux treatment at the temperature of 60-90 ℃ for 2-4 hours, washing and drying; dipping or co-dipping the pretreated activated carbon step by adopting soluble salt solution of the main catalyst and the auxiliary agent under the vacuum or normal pressure condition; drying the impregnated activated carbon at the drying temperature of 90-120 ℃; and reducing the dried activated carbon to obtain the catalyst. A metal alloy phase is formed on the surface of the carrier between the first active component and the second active component, so that the activity is moderate, the product selectivity is improved, and the service life of the catalyst is prolonged. The conversion rate of raw materials can reach 97.8%, and the highest CTFE selectivity can reach 96.2%.

CN105944734A discloses a catalyst for preparing chlorotrifluoroethylene by catalytic hydrogenation and dechlorination of trifluorotrichloroethane, which comprises a first catalyst, a second catalyst, an auxiliary agent and a carrier, wherein the first catalyst is one of cobalt or rhodium, the dosage of the first catalyst is 0.1-15% of the total mass of the catalyst, the second catalyst is one of chromium or manganese, the dosage of the second catalyst is 0.5-22% of the total mass of the catalyst, and the auxiliary agent is alkali metal potassium or rare earth metal rhenium, the dosage of the auxiliary agent is 0.1-5% of the total mass of the catalyst. The catalyst of the invention shows high activity in the reaction of preparing the chlorotrifluoroethylene by the hydrogenation and dechlorination of the trichlorotrifluoroethane, has mild reaction conditions and good operation stability, and is suitable for the process of preparing the chlorotrifluoroethylene by the hydrogenation and dechlorination of the trichlorotrifluoroethane.

These catalysts all have certain disadvantages such as consumption of expensive materials, low product yield, poor stability, etc., and the applicant has recognized that there is a continuing need in the art for further improvements in catalysts for the production of CTFE. The invention provides a catalyst with good selectivity, conversion rate and stability for producing vinyl halide (such as CTFE and the like) and a preparation method thereof.

Disclosure of Invention

The invention provides a catalyst for producing perhalogenated ethylene (such as CTFE) and a preparation method thereof, and also provides a method for producing halogenated ethylene.

The starting perhaloethane employed in the present invention is a perhaloethane corresponding to the formula:

CF_aCl_b-CF_dCl_f

wherein a is 0-3, b is 1-3, and a + b is 3; d is 0 to 3, f is 1 to 3, and d + f is 3; and b + f is 2 to 6.

Preferred perhaloethanes are 1, 2-dichlorotetrafluoroethane (fluorocarbon 114) or 1,1, 2-trichloro-1, 2, 2-trifluoroethane (fluorocarbon 113), with 1,1, 2-trichloro-1, 2, 2-trifluoroethane being particularly preferred.

The product is a perhaloethylene corresponding to the formula:

CF_mCl_n＝CF_xCl_y

wherein m is 0-2, n is 0-2, and m + n is 2; and x is 0 to 2, y is 0 to 2, and x + y is 2. The preferred product is chlorotrifluoroethylene.

The catalyst for producing perhalogenated ethylene provided by the invention at least comprises nitrides and/or carbides of VIII group and/or VIB group and/or IIB group metals as catalyst active components.

Furthermore, the catalyst for producing the perhalogenated ethylene provided by the invention also comprises a carrier, and nitrides and/or carbides of VIII group and/or VIB group and/or IIB group metals are used as catalyst active components. Preferably, the content of the active ingredient is 0.5 to 30 wt%. More preferably, the active ingredient is present in an amount of 1 to 20 wt%, or 2 to 15 wt%, or 5 to 15 wt%.

Preferably, the active component is a metal nitride or metal carbide. Preferably, the active component is cobalt nitride, molybdenum nitride, iron nitride, zinc nitride, tungsten nitride or nickel nitride.

Furthermore, the catalyst also comprises an auxiliary agent which is a nitride and/or carbide of a metal in the VIII group or IIB group and is different from the active component. Preferably, the auxiliary agent is one or more of copper nitride, iron carbide and palladium nitride. Preferably, the molar ratio of the metal elements in the active component to the metal elements in the auxiliary agent is 1:0.05-0.3, and the molar ratio of the metal elements in the active component to the metal elements in the auxiliary agent is 1:0.1-0.3 or 1: 0.1-0.2.

Preferably, the active component comprises at least nitrogen/carbide, such as nitrogen/cobalt carbide, nitrogen/molybdenum carbide, nitrogen/iron carbide, nitrogen/zinc carbide, nitrogen/tungsten carbide or nitrogen/nickel carbide; wherein nitrogen/carbide means a metal compound containing both nitride and carbide of a metal element.

Preferably, the carrier is alumina, titania, silica, molecular sieve.

The invention provides a preparation method of a catalyst for producing perhalogenated ethylene, which comprises the steps of (1) preparing a metal oxide precursor; step (2), temperature programming, reduction, nitridation and/or carbonization; and (3) passivating to obtain the catalyst.

Preferably, the step (1) is to weigh a certain amount of salt containing active metal components, roast the salt at high temperature for 2 to 6 hours in the air atmosphere, and obtain precursor metal oxide through tabletting and screening; or soaking the carrier in a first metal salt solution with a certain concentration, standing overnight at room temperature, drying at 80-160 ℃ for 2-10h in air atmosphere, roasting at air atmosphere for 2-6h, cooling, and drying to obtain the precursor metal oxide. Preferably, the precursor metal oxide is obtained by soaking the auxiliary agent salt solution after cooling and drying and carrying out the same treatment mode as the first soaking. Preferably, the calcination temperature is 400-800 ℃, and more preferably 400-600 ℃.

Preferably, in the step (2), the precursor metal oxide is subjected to temperature programming reduction nitridation and/or carbonization in a vacuum heating furnace, before nitridation and/or carbonization, the vacuum pumping is performed, then nitrogen purging is performed, and then reducing gas is introduced for nitridation and/or carbonization; preferably, the temperature is raised to 400 ℃ at 8-15 ℃/min, then raised to 800 ℃ at the final temperature of 600 ℃ at 0.2-5 ℃/min, preferably 650-750 ℃ or 700 ℃, and kept at the constant temperature for 2-5 h; preferably, the nitriding and/or carbonizing is at atmospheric pressure.

In one embodiment, the reducing gas is ammonia gas, mixed gas of ammonia gas and hydrogen gas, organic amine, and mixed gas of ammonia gas and organic amine; more preferably, the reducing gas is a mixed gas of ammonia gas and hydrogen gas, and the volume ratio of the mixed gas of ammonia gas and hydrogen gas is 1:0.5-4 or 1: 1-3.

In one embodiment, the reducing gas is one or more of ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monopropylamine, dipropylamine, ethylenediamine, monoethanolamine, and diethanolamine; preferably, the reducing gas is one or more of ammonia, diethylamine and diethanolamine; most preferably, the reducing gas is a mixed gas of ammonia gas and diethylamine, and the mixing volume ratio is 1:0.2-5, or 1:0.4-3, or 1: 0.5-2.

In one embodiment, the reducing gas is methane, ethane, propane, for carbonization.

Preferably, step (3) is carried out by cooling to room temperature in a reducing gas atmosphere after the nitriding and/or carbonizing are finished, and then carrying out O₂And N₂And (5) passivating the mixed gas. Preferably, O₂And N₂The volume ratio is 1: 99; the passivation time is 5-20 h.

The invention also provides application of the catalyst in preparing perhalogenated ethylene in catalysis, in particular application in preparing chlorotrifluoroethylene.

The present invention also provides a process for the production of perhalogenated ethylene, which comprises dechlorinating one or more halogenated ethanes in the gas phase in the presence of a catalyst and at least one compound which will react with chlorine from the dechlorination reaction in the presence of the catalyst in the gaseous reaction mixture.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the invention to these embodiments. It will be appreciated by those skilled in the art that the present invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.

Catalyst test conditions: CF is prepared by₂Cl-CFCl₂(R-113) and hydrogen mixture is fed to the bed containing the catalystIn the reactor (the reaction tube of the tubular reactor has an inner diameter of 12mm and a length of 50cm), the contact time was 8 seconds, and the feed molar ratio (R-113: H)₂) At 1:2 and a temperature of 500 ℃, the exit gas from the reactor was collected and analyzed for composition. For the non-supported catalyst, catalyst particles of 40-60 meshes are prepared and filled in the reaction tube.

1. Preparation of unsupported catalysts

Example 1

Weighing a certain amount of ammonium molybdate, roasting for 4 hours at 500 ℃ in an air atmosphere, tabletting, and screening to obtain a precursor oxide. And (3) carrying out temperature programming reduction nitridation and/or carbonization on the precursor oxide in a vacuum heating furnace. Before nitriding and/or carbonizing, vacuumizing and then introducing nitrogen for purging, wherein the reducing gas is ammonia gas which is subjected to oxygen removal and dehydration through a 3A molecular sieve and calcium oxide, heating to 400 ℃ at a constant speed and normal pressure at a speed of 10 ℃/min, heating to 600 ℃ at a speed of 0.2 ℃/min, and keeping the temperature for 5 hours. Then with O at room temperature₂And N₂And passivating the mixed gas with the volume ratio of 1:99 for 10 hours to obtain the catalyst.

Examples 2 to 18

Example 1 was adjusted in terms of the kind of active ingredient, the kind and content of auxiliary agent, final nitriding temperature, nitriding gas, and the like, and the specific conditions are shown in table 1. Wherein the cobalt source is cobalt nitrate, the nickel source is nickel nitrate, the zinc source is zinc nitrate, and the tungsten source is ammonium tungstate. In the examples containing the auxiliary, the active ingredient and the auxiliary salt are weighed to obtain the precursor metal oxide.

Example 19

The difference from example 1 is that the reducing gas is methane.

Comparative example 1

Comparative example 1 differs from example 1 in that a metal oxide catalyst is obtained without undergoing a nitriding and/or carbonizing step.

Table 1: unsupported catalyst component and test results

It can be seen that nitrides and/or carbides of metals such as cobalt, molybdenum, nickel, zinc, tungsten and the like show good catalytic performance for the reaction process of synthesizing CTFE from R-113.

It can be seen from the comparison of examples 1-5 that the catalysts obtained at different final nitriding temperatures have different performances, and the catalytic activity is different due to different sintering agglomeration degrees of the metal particles at different temperatures and different numbers of catalytic active sites; on the other hand, at different nitriding temperatures, the corresponding metals can present different valence states, and the metal nitride sintered at the temperature of 700 ℃ has higher catalytic activity. It can be seen from comparing examples 3 and 6-9 that the catalyst product with better catalytic activity and selectivity can be obtained by using the combined reducing gas of organic amine, organic amine and ammonia gas, because the organic amine contains N and C elements at the same time, not only nitrides but also partial carbides can be formed in the temperature programming process, and the formed nitrogen/carbides have better catalytic activity and selectivity.

After the metal element addition agent is added, the catalytic performance of the catalyst is improved, and particularly the catalyst containing the palladium element addition agent has more remarkable improvement.

2. Preparation of Supported catalysts

Example 20

Essentially as in example 1, the precursor oxide was prepared by a different method: soaking the carrier in an ammonium molybdate aqueous solution with a certain concentration according to the loading amount set by an experiment, after the carrier is aged at room temperature overnight, drying the carrier for 5 hours at 120 ℃ in an air atmosphere, roasting the carrier for 4 hours at 500 ℃ in an air atmosphere, and cooling and drying the carrier to obtain a precursor metal oxide. Wherein the catalyst carrier is alumina (such as a commercially available alumina carrier).

Examples 21 to 38

Example 20 was adjusted in terms of the kind of active ingredient, the kind and content of auxiliary agent, final nitriding temperature, nitriding gas, etc., and the specific conditions are shown in table 2. Wherein the cobalt source is cobalt nitrate, the nickel source is nickel nitrate, the zinc source is zinc nitrate, and the tungsten source is ammonium tungstate. In the embodiment containing the auxiliary agent, the auxiliary agent salt solution is impregnated after the temperature is reduced and the drying, and the precursor metal oxide is obtained through the same treatment mode as the first impregnation.

Example 39

The difference from example 20 is that the reducing gas is methane.

Comparative example 2

Comparative example 2 differs from example 20 in that a metal oxide catalyst was obtained without undergoing a nitriding and/or carbonizing step.

Table 2: supported catalyst component and test results

It can be seen that the nitrides and/or carbides of the metals such as cobalt, molybdenum, nickel, zinc, tungsten and the like loaded on the carrier show good catalytic performance for the reaction process of synthesizing CTFE from R-113, and the catalytic activity of the catalyst is improved to a certain extent compared with that of an unsupported catalyst.

It can be seen from comparison of examples 20-25 that, as the content of active ingredient increases, the catalytic activity of the supported catalyst gradually increases, and the catalytic performance tends to decrease in the period of more than 20 wt%, mainly because, as the content of active ingredient increases, the active sites of the metal particles increase and then decrease, and after reaching a certain content, the sintering agglomeration degree increases, and the number of the catalytic active sites decreases, resulting in decrease of the catalytic activity; on the other hand, at different nitriding temperatures, the metal assumes different valence states, and the metal nitride sintered at a temperature of 700 ℃ has higher catalytic activity. It can be seen from comparison of examples 23 and 26-29 that the reduction gas using the combination of organic amines, organic amines and ammonia gas can obtain a catalyst product with better catalytic activity and selectivity, which reflects the same rule as that of the unsupported catalyst, but has higher catalytic activity and selectivity compared with the unsupported catalyst, because the carbide is partially formed, the dispersibility is enhanced, and more active sites can be exposed for catalytic reaction.

All documents cited herein are incorporated by reference into this patent application as if each were individually incorporated by reference. Furthermore, it will be appreciated that various changes or modifications may be made by those skilled in the art after reading the above teachings of the present invention, and such equivalents may fall within the scope of the appended claims.