Vinylidene fluoride catalyst and preparation method thereof
阅读说明：本技术 一种偏氟乙烯催化剂及制备方法 (Vinylidene fluoride catalyst and preparation method thereof ) 是由 王朋朋 陈后文 赵景平 王章明 赖莺 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种偏氟乙烯催化剂及制备方法,其制备方法包括如下步骤：(1)：将碱土金属的可溶性盐加入到容器中,加入水搅拌溶解,加入尿素作为结构助剂,搅拌均匀,加入氟化铵溶液形成沉淀,然后将上述混合液置于水热釜中,150～400℃水热处理12～24h,用去离子水离心洗涤,得到粘稠混合物沉淀；(2)：将步骤(1)得到的粘稠混合物沉淀,在100～130℃条件下烘干,得到含有结构助剂的碱土金属氟化物；(3)：将步骤(2)中得到的碱土金属氟化物,在含氧氛围或者氮气氛围下,焙烧炉中以400～700℃,焙烧6～12h,除去结构助剂得到偏氟乙烯催化剂。本发明通过水热法与共沉淀法相结合,大幅度提高主催化剂比表面积,提高了催化剂的催化活性。(The invention discloses a vinylidene fluoride catalyst and a preparation method thereof, wherein the preparation method comprises the following steps: (1): adding soluble salt of alkaline earth metal into a container, adding water, stirring for dissolving, adding urea serving as a structural auxiliary agent, stirring uniformly, adding an ammonium fluoride solution to form a precipitate, then placing the mixed solution into a hydrothermal kettle, carrying out hydrothermal treatment at 150-400 ℃ for 12-24 hours, and carrying out centrifugal washing by using deionized water to obtain a viscous mixture precipitate; (2): precipitating the viscous mixture obtained in the step (1), and drying at 100-130 ℃ to obtain alkaline earth metal fluoride containing the structural assistant; (3): and (3) roasting the alkaline earth metal fluoride obtained in the step (2) for 6-12 h in a roasting furnace at 400-700 ℃ in an oxygen-containing atmosphere or a nitrogen atmosphere, and removing the structural auxiliary agent to obtain the vinylidene fluoride catalyst. The invention greatly improves the specific surface area of the main catalyst and the catalytic activity of the catalyst by combining a hydrothermal method and a coprecipitation method.)
1. The preparation method of the vinylidene fluoride catalyst is characterized by comprising the following steps:
step 1: adding soluble salt of alkaline earth metal into a container, adding water, stirring for dissolving, adding urea serving as a structural auxiliary agent, stirring uniformly, adding an ammonium fluoride solution to form a precipitate, then placing the mixed solution into a hydrothermal kettle, carrying out hydrothermal treatment at 150-400 ℃ for 12-24 hours, and carrying out centrifugal washing by using deionized water to obtain a viscous mixture precipitate;
step 2: precipitating the viscous mixture obtained in the step 1, and drying at 100-130 ℃ to obtain alkaline earth metal fluoride containing the structural assistant;
and step 3: and (3) roasting the alkaline earth metal fluoride containing the structural assistant obtained in the step (2) for 6-12 h in a roasting furnace at 400-700 ℃ in an oxygen-containing atmosphere or a nitrogen atmosphere, and removing the structural assistant to obtain the vinylidene fluoride catalyst.
2. The method for preparing a vinylidene fluoride catalyst according to claim 1, wherein: the alkaline earth metal is at least two of Mg, Ca, Sr and Ba.
3. The method for preparing a vinylidene fluoride catalyst according to claim 2, wherein: wherein the molar content of any alkaline earth metal is not more than 80%.
4. The method for preparing a vinylidene fluoride catalyst according to claim 2, wherein: the soluble salt of the alkaline earth metal is a chloride salt or a nitrate salt of at least two alkaline earth metals.
5. The method for preparing a vinylidene fluoride catalyst according to claim 1, wherein: in the step 1, the molar ratio of the soluble salt of the alkaline earth metal, the urea and the ammonium fluoride is 1: 0.1-3: 2.1.
6. The method for preparing a vinylidene fluoride catalyst according to claim 1, wherein: and 3, removing the structural auxiliary agent in a muffle furnace or a tubular furnace to obtain the vinylidene fluoride catalyst.
7. A vinylidene fluoride catalyst is characterized in that: prepared by the preparation method of any one of claims 1 to 6.
8. A preparation method of vinylidene fluoride is characterized by comprising the following steps: the vinylidene fluoride catalyst of claim 7 is used for preparing vinylidene fluoride by catalytic cracking of 1, 1-difluoro-1-chloroethane.
9. The method for preparing vinylidene fluoride according to claim 8, wherein: the temperature for preparing the vinylidene fluoride by catalytically cracking the 1, 1-difluoro-1-chloroethane is 250-600 ℃, the reaction pressure is normal pressure, the reaction is carried out in a fixed bed reactor, and the material of a reaction tube is nickel.
Technical Field
The invention belongs to the technical field of fluorine chemical industry, and particularly relates to vinylidene fluoride and a preparation method of a catalyst thereof.
Background
Vinylidene fluoride (CH2 ═ CF2, VDF) is one of the important monomers for fluorine industry, and is a key component in the production of polyvinylidene fluoride (PVDF) resins and Fluororubbers (FKM). By 2018, the global PVDF capacity is 11.54 ten thousand tons, and the demand is about 10 ten thousand tons. The PVDF resin has the characteristics of both fluororesin and general-purpose resin, has special performances such as piezoelectric property, thermoelectric property and the like in addition to good chemical corrosion resistance, high temperature resistance, oxidation resistance and radiation resistance, has the best comprehensive performance in all fluorine materials, and is the second largest variety of fluororesin which is second to PTFE. It can be widely used in chemical engineering, electronic and semiconductor, building coating, oil and gas pipeline, medicine, etc. But P vinylidene fluoride still has great development space in the fields of solar backboard films, piezoelectric film sensors, lithium battery binders and the like.
At present, the industrial production of vinylidene fluoride mainly adopts a method of removing HCl by cracking 1, 1-difluoro-1-chloroethane (HCFC-142b) through an empty tube, wherein the cracking temperature is 600-800 ℃, the conversion rate of HCFC-142b is about 80-100%, and the selectivity of vinylidene fluoride is about 85-95%. However, under high temperature conditions, HCFC-142b is susceptible to HF removal and disproportionation. In addition, a large amount of carbon deposit is generated in the high-temperature tubular reactor and blocks the pipeline, and the industrial production process needs to be stopped periodically to remove the carbon deposit; moreover, the energy consumption of the empty tube cracking is high.
The catalyst is introduced to catalytically crack HCFC-142b to prepare the vinylidene fluoride, so that the reaction temperature can be greatly reduced, the energy consumption is reduced, and the problem of carbon deposition is solved. At present, the catalyst mainly comprises active carbon, metal oxide and metal fluoride, the active carbon catalyst is easy to inactivate and difficult to regenerate, and the metal oxide is easy to react with hydrogen chloride in a product to cause the loss of active components. Therefore, in recent years, the catalysts have been studied mainly based on metal fluorides. Chinese patent CN111905779A discloses that different HCFC-142b conversion rates and vinylidene fluoride selectivity can be obtained by preparing a catalyst with BaF2 as a main catalyst and introducing a large amount of alkaline earth metal, transition metal and lanthanide metal as promoters through a hydrothermal method. Chinese patent CN109180420A discloses a composite metal fluoride catalyst prepared by grinding or precipitation method and using alkaline earth metal, transition metal and lanthanide as core, which can obtain HCFC-142b conversion rate higher than 50% and vinylidene fluoride selectivity lower than 90%. Therefore, the development of a catalyst which is simple in preparation process, stable and efficient is of great significance.
Disclosure of Invention
The invention aims to solve the technical problem of providing the vinylidene fluoride catalyst and the preparation method thereof, and the vinylidene fluoride catalyst has the advantages of simple process and low cost.
In order to solve the technical problems, the invention adopts the following technical scheme:
on one hand, the preparation method of the vinylidene fluoride catalyst is provided, and comprises the following steps:
step 1: adding soluble salt of alkaline earth metal into a container, adding water, stirring for dissolving, adding urea serving as a structural auxiliary agent, stirring uniformly, adding an ammonium fluoride solution to form a precipitate, then placing the mixed solution into a hydrothermal kettle, carrying out hydrothermal treatment at 150-400 ℃ for 12-24 hours, and carrying out centrifugal washing by using deionized water to obtain a viscous mixture precipitate;
step 2: precipitating the viscous mixture obtained in the step 1, and drying at 100-130 ℃ to obtain alkaline earth metal fluoride containing the structural assistant;
and step 3: and (3) roasting the alkaline earth metal fluoride containing the structural assistant obtained in the step (2) for 6-12 h in a roasting furnace at 400-700 ℃ in an oxygen-containing atmosphere or a nitrogen atmosphere, and removing the structural assistant to obtain the vinylidene fluoride catalyst.
On the other hand, the vinylidene fluoride catalyst is prepared by the preparation method.
Finally, the preparation method of the vinylidene fluoride is also provided, and the vinylidene fluoride is prepared by adopting the vinylidene fluoride catalyst to catalytically crack the 1, 1-difluoro-1-chloroethane.
By adopting the technical scheme, compared with the prior art, the invention has the following beneficial effects:
according to the invention, alkaline earth metal fluoride is used as a main catalyst, urea is introduced as a structural auxiliary agent, a coprecipitation method is used for preparing various soluble alkaline earth metal salts into alkaline earth metal fluoride solid solution precipitated particles, then soluble urea is gradually condensed into an insoluble condensate in a hydrothermal process, the alkaline earth metal fluoride solid solution precipitated particles are adsorbed on the outer surface of the alkaline earth metal fluoride solid solution precipitated particles, the insoluble condensate is decomposed and removed in a subsequent roasting process, and the hydrothermal method and the coprecipitation method are combined, so that the specific surface area of the main catalyst is greatly increased, and the catalytic activity of the catalyst is improved.
The following detailed description will explain the present invention and its advantages.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to develop a vinylidene fluoride catalyst with simple manufacturing process, stability and high efficiency, the specific embodiment of the invention provides a preparation method of the vinylidene fluoride catalyst, which comprises the following steps:
step 1: adding soluble salt of alkaline earth metal into a container, adding water, stirring for dissolving, adding urea serving as a structural auxiliary agent, stirring uniformly, adding an ammonium fluoride solution to form a precipitate to form a mixed solution, placing the mixed solution into a hydrothermal kettle, carrying out hydrothermal treatment at 150-400 ℃ for 12-24 hours, and carrying out centrifugal washing by using deionized water to obtain a viscous mixture precipitate;
step 2: precipitating the viscous mixture obtained in the step 1, and drying at 100-130 ℃ to obtain alkaline earth metal fluoride containing the structural assistant;
and step 3: and (3) roasting the alkaline earth metal fluoride containing the structural assistant obtained in the step (2) for 6-12 h at 400-700 ℃ in an oxygen-containing atmosphere or a nitrogen atmosphere in a roasting furnace, and removing the structural assistant to obtain the vinylidene fluoride catalyst.
Wherein the alkaline earth metal is at least two of Mg, Ca, Sr and Ba. And wherein the molar content of any alkaline earth metal does not exceed 80%. The soluble salt of the alkaline earth metal is a chloride salt of at least two alkaline earth metals, such as magnesium chloride, calcium chloride, strontium chloride, barium chloride, or a nitrate salt, such as magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate.
Further, the molar ratio of the soluble salt of the alkaline earth metal, the urea and the ammonium fluoride in the step 1 is 1: 0.1-3: 2.1, such as 1:0.1, 5:1, 4:1, 3:1, 2:1 and 3: 2.1.
Preferably, the step 3 is to remove the structural assistant in a muffle furnace or a tubular furnace to obtain the vinylidene fluoride catalyst.
In addition, on the other hand, the vinylidene fluoride catalyst is also provided and is prepared by the preparation method.
Finally, the preparation method of the vinylidene fluoride is also provided, and the vinylidene fluoride is prepared by catalytic cracking of the 1, 1-difluoro-1-chloroethane by adopting the vinylidene fluoride catalyst. The temperature for preparing the vinylidene fluoride is 250-600 ℃, the reaction pressure is normal pressure, the reaction is carried out in a fixed bed reactor, and the material of a reaction tube is nickel.
Example one
According to the Ca: the molar ratio of Ba is 1: 1, weighing 0.1mol of BaCl2·2H2O、0.1molCaCl2Dissolving in 150ml deionized water, stirring and mixing for 0.5h at a stirring speed of 500r/min, then weighing 0.04mol of urea, adding into the mixed solution, stirring and mixing for 0.5h at a stirring speed of 500r/min, weighing 0.42mol of NH4F was dissolved in 30ml of deionized water and NH was added at a stirring rate of 700r/min4Slowly dripping the solution F into the mixed solution, continuously stirring for 2h after dripping is finished, then placing the obtained precipitation mixed solution into a hydrothermal reaction kettle, performing hydrothermal treatment for 24h at 200 ℃, cooling and taking out, centrifugally washing for 3 times by using deionized water, placing into an oven, drying for 12h at 110 ℃, taking out, placing into a muffle furnace, and placing in a nitrogen atmosphereAnd roasting at 250 deg.c for 6 hr, heating to 500 deg.c at 10 deg.c/min for 6 hr to obtain the catalyst of the present invention, and sieving with sample sieving to obtain 20-40 mesh catalyst for reaction.
The catalyst prepared in the embodiment 1 is applied to catalytic cracking of HCFC-142b to prepare vinylidene fluoride, the reaction is carried out in a fixed bed reactor, a reaction tube is a nickel tube (made of N600), the reaction pressure is normal pressure, the reaction temperature is 350 ℃, mixed gas of nitrogen and HCFC-142b is introduced, the molar ratio of the nitrogen to the HCFC-142b is 1: 1, the space velocity is 600h-1Sampling and analyzing, and obtaining the following results: the conversion of HCFC-142b was 75.6%, and the selectivity of vinylidene fluoride was 96.5%.
Example 2
According to the Ca: the molar ratio of Ba is 1: 1, weighing 0.05mol of BaCl2·2H2O、0.05molCaCl2Dissolving in 150ml deionized water, stirring and mixing for 0.5h at a stirring speed of 500r/min, then weighing 0.02mol of urea, adding into the mixed solution, stirring and mixing for 0.5h at a stirring speed of 500r/min, weighing 0.21mol of NH4F was dissolved in 30ml of deionized water and NH was added at a stirring rate of 700r/min4And slowly dripping the solution F into the mixed solution, continuing stirring for 2h after dripping is finished, then placing the obtained precipitation mixed solution into a hydrothermal reaction kettle, performing hydrothermal treatment for 24h at 200 ℃, cooling and taking out, centrifugally washing for 3 times by using deionized water, placing into an oven for drying at 110 ℃ for 12h, taking out, placing into a tubular furnace, roasting for 6h at 250 ℃ in an oxygen-containing atmosphere, then heating to 500 ℃ at a heating rate of 10 ℃/min, roasting for 6h at 500 ℃ to obtain the catalyst, and screening by using a sample sieve for tabletting to obtain the catalyst with 20-40 meshes for reaction.
The catalyst prepared in the embodiment 2 is applied to catalytic cracking of HCFC-142b to prepare vinylidene fluoride, the reaction is carried out in a fixed bed reactor, a reaction tube is a nickel tube (made of N600), the reaction pressure is normal pressure, the reaction temperature is 350 ℃, mixed gas of nitrogen and HCFC-142b is introduced, the molar ratio of the nitrogen to the HCFC-142b is 1: 1, the space velocity is 600h-1Sampling and analyzing, and obtaining the following results: HCFC-142b conversion was 65.6%, partialThe selectivity to vinyl fluoride was 90.9%.
Example 3
According to Sr: the molar ratio of Ba is 1: 1, weighing 0.1mol of BaCl2·2H2O、0.1molSrCl2·6H2Dissolving O in 150ml deionized water, stirring and mixing for 0.5h at the stirring speed of 500r/min, then weighing 0.05mol of urea, adding into the mixed solution, stirring and mixing for 0.5h at the stirring speed of 500r/min, weighing 0.42mol of NH4F was dissolved in 30ml of deionized water and NH was added at a stirring rate of 700r/min4And slowly dripping the solution F into the mixed solution, continuing stirring for 2 hours after dripping is finished, then placing the obtained precipitation mixed solution into a hydrothermal reaction kettle, performing hydrothermal treatment for 24 hours at 200 ℃, cooling and taking out, centrifugally washing for 3 times by using deionized water, placing into an oven for drying at 110 ℃ for 12 hours, taking out, placing into a muffle furnace, roasting for 6 hours at 250 ℃ in a nitrogen atmosphere, then heating to 500 ℃ at a heating rate of 10 ℃/min, roasting for 6 hours at 500 ℃ to obtain the catalyst, and tabletting to obtain the 20-40-mesh catalyst for reaction by using a sample sieve.
The catalyst prepared in the embodiment 3 is applied to catalytic cracking of HCFC-142b to prepare vinylidene fluoride, the reaction is carried out in a fixed bed reactor, a reaction tube is a nickel tube (made of N600), the reaction pressure is normal pressure, the reaction temperature is 350 ℃, mixed gas of nitrogen and HCFC-142b is introduced, the molar ratio of the nitrogen to the HCFC-142b is 1: 1, the space velocity is 600h-1Sampling and analyzing, and obtaining the following results: the conversion of HCFC-142b was 94.2%, and the selectivity of vinylidene fluoride was 99.8%.
Example 4
According to Sr: the molar ratio of Ba is 1: 1, weighing 0.1mol of BaCl2·2H2O、0.1molSrCl2·6H2Dissolving O in 150ml deionized water, stirring and mixing for 0.5h at the stirring speed of 500r/min, then weighing 0.05mol of urea, adding into the mixed solution, stirring and mixing for 0.5h at the stirring speed of 500r/min, weighing 0.42mol of NH4F was dissolved in 30ml of deionized water and NH was added at a stirring rate of 700r/min4Slowly dripping the solution F into the mixed solution, continuously stirring for 2h after the dripping is finished, and then mixingPlacing the obtained precipitation mixed solution in a hydrothermal reaction kettle, carrying out hydrothermal treatment for 24h at 200 ℃, cooling, taking out, carrying out centrifugal washing for 3 times by using deionized water, placing in an oven for drying for 12h at 110 ℃, taking out, placing in a tubular furnace, roasting for 6h at 250 ℃ in an oxygen-containing atmosphere, then heating to 500 ℃ at a heating rate of 10 ℃/min, roasting for 6h at 500 ℃ to obtain the catalyst, and screening the pressed pieces by using a sample sieve to obtain the catalyst with 20-40 meshes for reaction.
While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that the invention is not limited thereto, and may be embodied in other forms without departing from the spirit or essential characteristics thereof. Any modification which does not depart from the functional and structural principles of the present invention is intended to be included within the scope of the claims.