CN114292157B - Method for preparing 1, 1-difluoroethylene by using R143a - Google Patents
Method for preparing 1, 1-difluoroethylene by using R143a Download PDFInfo
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- CN114292157B CN114292157B CN202210001799.0A CN202210001799A CN114292157B CN 114292157 B CN114292157 B CN 114292157B CN 202210001799 A CN202210001799 A CN 202210001799A CN 114292157 B CN114292157 B CN 114292157B
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Abstract
The invention discloses a method for preparing 1, 1-difluoroethylene by using R143a, which comprises the following steps: (a) preparing; (b) cleavage; (c) removing impurities. The invention has simple process, easy operation and control, convenient catalyst replacement, good catalytic effect, high reaction conversion rate, high selectivity of the final product and low impurity content, and ensures the purity of the final product.
Description
Technical Field
The invention belongs to the technical field of 1, 1-difluoroethylene preparation, and particularly relates to a method for preparing 1, 1-difluoroethylene by using R143 a.
Background
1, 1-difluoroethylene (also known as vinylidene fluoride or VDF) is one of the important varieties of fluoroolefins, mainly used for the production of polyvinylidene fluoride resins, fluororubbers and fluorocopolymers such as vinylidene fluoride-hexafluoropropylene, vinylidene fluoride-vinylidene fluoride, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene, etc. In addition, fluororubber obtained by copolymerizing vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene is one of indispensable and alternative base materials in the modern industry, especially in the high technical field, due to the excellent high temperature resistance, oil resistance, solvent resistance and physical and mechanical properties.
The production process of preparing 1, 1-difluoroethylene by the HF-free method of R143a (1, 1-trifluoroethane) can be carried out at low temperature by catalytic pyrolysis, has low energy consumption, is a common 1, 1-difluoroethylene preparation process, but has the problems of serious corrosion of a cracker, low reaction conversion rate, high impurity content, low selectivity and purity of the 1, 1-difluoroethylene, catalyst loss, easy inactivation and the like, and the catalyst is inconvenient to replace.
Disclosure of Invention
The invention aims to solve the technical problems in the prior art and provides a method for preparing 1, 1-difluoroethylene by using R143a, which has the advantages of simple process, easy operation and control, convenient catalyst replacement, good catalytic effect, high reaction conversion rate, high selectivity of the final product, low impurity content and ensured purity of the final product.
In order to solve the technical problems, the invention adopts the following technical scheme:
a process for preparing 1, 1-difluoroethylene by R143a, comprising the steps of:
(a) Preparation: preparing a supported catalyst;
(1) firstly, loading a supported catalyst into a fixing groove of a carrier plate, and then clamping a grid plate in the fixing groove to limit the grid plate on the carrier plate;
(2) the carrier plate is arranged on a separation frame, and then the separation frame is arranged in a metal lining of the cracking reactor, so that the separation frame separates the inner space of the cracking reactor;
(3) the positioning column on the side surface of the sealing cover passes through the positioning through hole on the positioning base on the side surface of the cracking reactor until the fixing ring on the cracking reactor is abutted against the outer edge of the sealing cover, and then the stroke cylinder is started, and the stroke cylinder drives the stop plate to pass through the stop through hole on the positioning column through the fixing plate, so that the sealing cover is limited and fixed on the cracking reactor;
(4) the reactors are connected through pipelines;
(b) Cracking:
(1) turning on the preheater and the electric heaters in the cracking reactor, introducing raw material gas R143a into the preheater for preheating, and introducing nitrogen into the cracking reactor for purging to remove air in the cracking reactor;
(2) preheating raw material gas, introducing the preheated raw material gas into a cracking reactor for cracking reaction, and cooling the reacted mixed gas in a condenser;
(c) Removing impurities: the cooled mixed gas enters an alkaline washing tower for deacidification, the deacidified gas enters a dryer for dehydration, and the dehydrated gas enters a collecting bag for collection to obtain the 1, 1-difluoroethylene.
Further, the specific implementation of drying in the step (c) is as follows: the deacidified gas enters the dryer from the bottom, enters the drying box filled with the soda lime from the flow distribution holes on the side wall of the flow guide pipe to be dehydrated, flows out from the flow distribution holes on the top surface of the drying box, gradually rises between the adsorption plates which are distributed in an up-down staggered mode, continuously contacts with the allochroic silica gel on the surfaces of the adsorption plates to be dehydrated again, and is discharged from the top after secondary dehydration, in the drying process, the sufficient contact area and contact time between the mixed gas and the water absorbent are ensured, the water absorption effect is good, the moisture in the mixed gas is effectively removed through the secondary water absorption effect, and the purity of the collected 1, 1-difluoroethylene is improved.
Further, be equipped with adsorption plate and drying box in the desicator, the adsorption plate is vertically crisscross the top that distributes at the drying box, the surface of adsorption plate is equipped with the allochroic silica gel, the bottom of drying box is equipped with the honeycomb duct, be equipped with the branch pore on the lateral wall of honeycomb duct, the top surface of drying box is equipped with the circulation hole, the branch pore all communicates with each other with the inner chamber of drying box, soda lime is equipped with in the inner chamber of drying box, gas gets into in the desicator, can only get into the honeycomb duct, get into the inner chamber of drying box through the branch pore, divided into many little strands, the velocity of flow reduces, the dwell time in the drying box becomes longer, forced gas and soda lime contact, the effect of absorbing water has been improved, gas after the effect of absorbing water by one-level is flowed from the circulation hole, by the reposition of redundant personnel, the velocity of flow continues to reduce, it goes upward along the bending channel that forms between upper and lower adsorption plate, the flow path is long, contact time with allochroic silica gel, the dehydration effect is good.
Furthermore, the inner top of the dryer is provided with a dust removing filter screen, and along with the continuous progress of the reaction, some particle impurities such as active carbon particles, metal particles, soda lime particles and the like are generated in the system, and the dust removing filter screen is used for intercepting the particle impurities, so that the collection purity of the 1, 1-difluoroethylene can be improved.
Further, the specific practice of cooling in step (c) is as follows: mixed gas enters the condenser from the top, condensate passes through the spiral pipe in the condenser in a low-in and high-out mode, a low-temperature environment is formed in the inner cavity of the condenser, the mixed gas is cooled, the cooled mixed gas is discharged from the bottom, the cooling range is large, quick cooling is realized, the cooling effect is good, the cooling liquid can be reused, and the cost is reduced.
Further, the preparation process of the supported catalyst in the step (a) comprises the following steps: the method is characterized in that the flaky active carbon is boiled and washed by nitric acid for 1-2 hours, then deionized water is used for washing to be neutral, the active carbon is immersed in a metal chloride solution for 8-10 hours, and is dried in a drier at 100-110 ℃ for 8-10 hours after being filtered, and then the catalyst is prepared by adopting an immersion method, so that the method is easy to operate, the problems that the existing method is difficult to directly fill the metal chloride into a cracking reactor and easy to block a pipeline are solved, the reaction temperature can be reduced by adding the metal chloride, the reaction conversion rate and the selectivity of 1, 1-difluoroethylene are improved, the catalytic effect is enhanced, the energy consumption is reduced, and the phenomenon that coking is easy to occur in the cracking process is solved.
Further, in step (a), the trapezoid strake of the carrying plate is clamped into the trapezoid clamping groove on the separation frame, so that the carrying plate is limited on the separation frame, the outer side edge of the separation frame is clamped into the inner clamping groove on the metal lining, and the separation frame is limited in the cracking reactor.
Further, an electric heater is arranged on the inner bottom surface of the cracking reactor in the step (a), a fixed ring and a fixed support are arranged outside the cracking reactor, a stroke cylinder is arranged on the fixed support, a fixed plate is arranged at the output end of the stroke cylinder, a stop plate is arranged on the fixed plate, a positioning base is arranged on the fixed ring, a positioning through hole is arranged on the positioning base, a positioning column corresponding to the positioning through hole is arranged on the side surface of the sealing cover, a stop through hole corresponding to the stop plate is arranged on the positioning column, quick installation and positioning of the sealing cover on the cracking reactor are realized, the installation difficulty is reduced, the stop plate limits the positioning column to be separated from the positioning base, the sealing cover is limited and fixed on the cracking reactor, the sealing cover is in tight contact with the positioning base, and a gap is small, so that good sealing performance is ensured.
The separation frame comprises a central shaft, a first separation plate, a second separation plate and a third separation plate, wherein the first separation plate, the second separation plate and the third separation plate are circumferentially distributed on the central shaft, the top surface of the first separation plate is flush with the top surface of the second separation plate, the top surface of the second separation plate is higher than the top surface of the third separation plate, the bottom surface of the first separation plate is flush with the bottom surface of the third separation plate, the bottom surface of the second separation plate is higher than the bottom surface of the third separation plate, trapezoid clamping grooves are formed in the first separation plate, the second separation plate and the third separation plate, one end of each trapezoid clamping groove is sealed, one end of each trapezoid clamping groove is opened, the separation frame separates an inner space of the cracking reactor into reaction areas which are sequentially communicated, the temperature distribution is uniform, the reaction is facilitated, the retention time of raw gas in the cracking reactor is guaranteed, the contact with a metal lining and a load type catalyst is sufficient, the catalytic effect is improved, the length of the cracking reactor is reduced, and the cost is reduced.
The metal lining is arranged in the cracking reactor, so that the internal structural strength of the cracking reactor is improved, HF generated in the cracking reaction process can corrode the metal lining to generate metal ions, the metal ions play a catalytic role in the cracking reaction, the catalyst is supplemented, the reaction is complete, and the problem of activity reduction caused by catalyst loss is solved. The metal lining is provided with the inner clamping grooves corresponding to the first baffle, the second baffle and the third baffle, so that the separation frame can be quickly installed and positioned in the cracking reactor, the positioning difficulty is reduced, the installation is reliable, and the separation frame cannot rotate circumferentially. The pressing block used for pressing the center shaft is arranged on the inner bottom surface of the sealing cover, the center shaft is pressed by the pressing block after the sealing cover is closed, the axial movement of the separation frame is blocked, and the installation stability of the separation frame is improved.
Further, the reaction temperature of the cleavage reactor in the step (b) is 200-500 ℃, the reaction pressure is normal pressure, and the space velocity is 50-250h -1 。
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
1. the separation frame is detachable from the cracking reactor, the separation frame is taken out, the carrier plate can be detached, and the supported catalyst can be replaced and replenished, so that the method is simple and convenient, and the problem that the catalyst in the cracking tube is difficult to replace and replenish in the prior art is solved; the supported catalyst is regularly distributed in the cracking reactor, covers the inner cavity of the cracking reactor, has large coverage area and good catalytic effect, and reduces the subsequent cleaning difficulty; the internal space of the cracking reactor is divided into the reaction areas which are communicated in sequence by the separation frame, the temperature distribution is uniform, the complete reaction is facilitated, the residence time of the raw material gas in the cracking reactor is ensured, the raw material gas is fully contacted with the metal lining and the supported catalyst, the catalytic effect is improved, the length of the cracking reactor is reduced, and the cost is reduced.
2. The stroke cylinder drives the stop plate to pass through the stop through hole on the positioning column through the fixing plate, and the stop plate limits the positioning column to be separated from the positioning base, so that the sealing cover is limited and fixed on the cracking reactor, the sealing cover is in close contact with the cracking reactor, the gap at the joint is small, good tightness is ensured, the manual fastening operation is replaced, and the fixing is durable and reliable, labor-saving and convenient; at the moment, the sealing cover presses the middle shaft through the pressing block to prevent the separation frame from axially moving, so that the installation stability of the separation frame is improved.
3. In the drying process, the deacidified gas enters the dryer from the bottom, can only flow into the guide pipe, then enters the inner cavity of the drying box from the flow dividing hole, is divided into multiple small strands, reduces the flow speed, prolongs the residence time in the drying box, forces the gas to contact with the soda lime, and improves the water absorption effect. The gas after the primary water absorption flows out from the circulation hole, is split again, the flow speed is continuously reduced, and gradually moves upwards along the bending channel formed between the upper adsorption plate and the lower adsorption plate, continuously contacts with the allochroic silica gel on the surface of the adsorption plate, and is dehydrated again, and the flow path is long, so that the water removal effect is good. In the drying process, the sufficient contact area and contact time of the mixed gas and the water absorbent are ensured, the water absorption is more sufficient, the water in the mixed gas is effectively removed through the secondary water absorption effect, and the purity of the collected 1, 1-difluoroethylene is improved.
Drawings
The invention is further described below with reference to the accompanying drawings:
FIG. 1 is a schematic diagram showing the structure of a system for producing 1, 1-difluoroethylene according to the present invention;
FIG. 2 is a schematic view showing the external structure of a cleavage reactor according to the present invention;
FIG. 3 is a schematic view showing the connection structure of the cleavage reactor and the separation frame in the present invention;
FIG. 4 is a schematic view of the structure of the connection of the cleavage reactor and the sealing cap in the present invention;
FIG. 5 is a schematic view of the structure of the seal cap of the present invention;
FIG. 6 is a schematic view of the structure of the connection of the separator and the carrier plate according to the present invention;
FIG. 7 is a schematic view of a separator of the present invention;
FIG. 8 is a schematic view of the connection structure of the carrier plate and the grid plate according to the present invention;
fig. 9 is a schematic view showing an internal structure of the dryer according to the present invention.
In the figure: 1-a carrying plate; 2-fixing grooves; 3-trapezoid strakes; 4-a separation frame; 5-a central shaft; 6-a first separator; 7-a second separator; 8-a third separator; 9-a trapezoidal clamping groove; 10-a cracking reactor; 11-an electric heater; 12-a discharge hole; 13-sealing the cover; 14-exhaust port; 15-a raw material gas inlet; 16-nitrogen inlet; 17-a fixing ring; 18-fixing a bracket; 19-stroke cylinder; 20-fixing plates; 21-a stop plate; 22-positioning a base; 23-positioning through holes; 24-positioning columns; 25-a stop through hole; 26-briquetting; a 27-metal liner; 28-an inner clamping groove; 29-supported catalyst; 30-grid plates; 31-a preheater; a 32-condenser; 33-an alkaline washing tower; 34-a dryer; 35-collecting bags; 36-spiral tube; 37-adsorbing plate; 38-drying box; 39-color-changing silica gel; 40-a flow guiding pipe; 41-a diversion hole; 42-a flow hole; 43-soda lime; 44-a dust removing filter screen.
Detailed Description
As shown in fig. 1 to 9, a method for preparing 1, 1-difluoroethylene by R143a according to the present invention comprises the steps of:
(a) Preparation: preparation of a supported catalyst: the flaky active carbon is boiled and washed by nitric acid for 1-2 hours, and pore canals of the active carbon are cleaned, so that the reaming effect is achieved. Then deionized byWashing with water, measuring the pH value of the water by a pH meter, and stopping washing when the pH value is 6.5-7; soaking the activated carbon in metal chloride solution for 8-10 hr, filtering, drying in drier at 100-110deg.C for 8-10 hr, wherein the metal chloride is selected from one of barium chloride, ferric chloride and cupric chloride, and has promoting effect on R143a cracking, and the metal chloride solution is preferably CuCl with mass fraction of 20% 2 The solution is prepared into the catalyst by adopting an impregnation method, the operation is easy, the problems that the existing method is difficult to directly fill the metal chloride into a cracking reactor and the pipeline is easy to block are solved, the addition of the metal chloride can reduce the reaction temperature, improve the reaction conversion rate and the selectivity of 1, 1-difluoroethylene, strengthen the catalytic action, reduce the energy consumption and alleviate the phenomenon that coking is easy to occur in the cracking process.
The upper and lower surface of carrying plate 1 all is equipped with fixed recess 2, one side of carrying plate 1 is equipped with trapezoidal strake 3, separating frame 4 includes axis 5, first baffle 6, second baffle 7 and third baffle 8, first baffle 6, second baffle 7, third baffle 8 encircle and distribute on axis 5, the top surface of first baffle 6 flushes with the top surface of second baffle 7, the top surface of second baffle 7 is higher than the top surface of third baffle 8, the bottom surface of first baffle 6 flushes with the bottom surface of third baffle 8, the bottom surface of second baffle 7 is higher than the bottom surface of third baffle 8, all be equipped with on first baffle 6, second baffle 7 and the third baffle 8 with trapezoidal draw-in groove 9 that trapezoidal strake 3 corresponds, trapezoidal draw-in groove 9 is one end closed one end opening form.
An electric heater 11 is arranged on the inner bottom surface of the cracking reactor 10, a discharge port 12 is arranged at the bottom of the cracking reactor 10, an exhaust port 14, a raw material gas inlet 15 and a nitrogen gas inlet 16 are arranged on a sealing cover 13, a fixed ring 17 and a fixed support 18 are arranged outside the cracking reactor 10, a stroke cylinder 19 is arranged on the fixed support 18, a fixed plate 20 is arranged at the output end of the stroke cylinder 19, a stop plate 21 is arranged on the fixed plate 20, a positioning base 22 is arranged on the fixed ring 17, a positioning through hole 23 is arranged on the positioning base 22, a positioning column 24 corresponding to the positioning through hole 23 is arranged on the side surface of the sealing cover 13, a stop through hole 25 corresponding to the stop plate 21 is arranged on the positioning column 24, and a pressing block 26 for pressing a center shaft 5 is arranged on the inner bottom surface of the sealing cover 13.
The metal lining 27 is arranged in the cracking reactor 10, the metal lining 27 is made of copper alloy, the internal structural strength of the cracking reactor 10 is improved, HF generated in the cracking reaction process can corrode the metal lining 27 to generate metal ions, the metal ions play a catalytic role in the cracking reaction, the catalyst is supplemented, the reaction is complete, the problem of activity reduction caused by catalyst loss is solved, and the problem of serious corrosion on the inner wall of the cracking reactor 10 is avoided. The metal lining 27 is provided with inner clamping grooves 28 corresponding to the first baffle plate 6, the second baffle plate 7 and the third baffle plate 8, so that the separation frame 4 can be quickly installed and positioned in the cracking reactor 10, the positioning difficulty is reduced, the installation is reliable, and the separation frame 4 cannot rotate circumferentially.
(1) The supported catalyst 29 is firstly filled in the fixing groove 2 of the carrier plate 1, and then the grid plate 30 is clamped in the fixing groove 2, so that the grid plate 30 is limited on the carrier plate 1, the grid plate 30 plays a role in limiting and protecting the supported catalyst 29, the reliability of the supported catalyst 29 mounted on the carrier plate 1 is improved, and the supported catalyst is not easy to break away due to air impact.
(2) The trapezoid strake 3 of the carrying plate 1 is clamped into the trapezoid clamping groove 9 on the separation frame 4, the carrying plate 1 is limited on the separation frame 4, the outer side edge of the separation frame 4 is clamped into the inner clamping groove 28 on the metal lining 27, the separation frame 4 is limited in the cracking reactor 10, the positioning is convenient, the mounting difficulty is low, the dismounting is convenient, the cleaning and the replacement are convenient, the carrying catalyst 29 is regularly distributed in the cracking reactor 10, the inner cavity of the cracking reactor 10 is covered, the coverage area is large, the catalytic effect is good, and the subsequent cleaning difficulty is also reduced.
(3) The positioning column 24 on the side surface of the sealing cover 13 passes through the positioning through hole 23 on the positioning base 22, so that the sealing cover 13 is quickly installed and positioned on the cracking reactor 10, the installation difficulty is reduced, and the fixing ring 17 on the cracking reactor 10 is abutted against the outer edge of the sealing cover 13; then, the travel cylinder 19 is started, the travel cylinder 19 drives the stop plate 21 to pass through the stop through hole 25 on the positioning column 24 through the fixing plate 20, the stop plate 21 limits the positioning column 24 to be separated from the positioning base 22, the sealing cover 13 is limited and fixed on the cracking reactor 10, the sealing cover 13 is tightly contacted with the fixing ring 17, the gap at the joint is small, good sealing performance is ensured, the manual fastening operation is replaced, and the fixing is durable and reliable, labor is saved and convenient. At the moment, the sealing cover 13 presses the middle shaft 5 through the pressing block 26 to prevent the separation frame 4 from axially moving, so that the installation stability of the separation frame 4 is improved.
(4) The nitrogen tank filled with nitrogen is connected with the sealing cover 13 through a pipeline, the storage tank filled with raw material gas R143a is connected with the preheater 31 through a pipeline, the preheater 31 is connected with the sealing cover 13 through a pipeline, the cracking reactor 10 is connected with the condenser 32 through a pipeline, the condenser 32 is connected with the alkaline washing tower 33 through a pipeline, the alkaline washing tower 33 is connected with the dryer 34 through a pipeline, the dryer 34 is connected with the collecting bag 35 through a pipeline, and finally the air tightness of each reactor is checked.
(b) Cracking:
(1) the preheater 31 and the electric heater 11 in the cracking reactor 10 are turned on, and the raw material gas R143a is fed into the preheater 31 for preheating to 150 ℃ so that the raw material gas R143a can reach the required reaction temperature during the catalytic cracking reaction; simultaneously, nitrogen is introduced into the cracking reactor 10 for purging, so that air in the cracking reactor 10 is removed, and the activated carbon carrier is burnt when being contacted with the air after the reaction temperature is increased, so that the catalyst is deactivated, and the safety is improved.
(2) The raw material gas is preheated and then is introduced into a cracking reactor 10 for cracking reaction, the reaction temperature of the cracking reactor 10 is 200-500 ℃, preferably 250-480 ℃, the reaction pressure is normal pressure, and the space velocity is 50-250h -1 Preferably at a space velocity of 80 to 220h -1 . The separation frame 4 separates the internal space of the cracking reactor 10 into reaction areas which are communicated in sequence, the temperature distribution is uniform, the reaction is complete, the residence time of the raw material gas in the cracking reactor 10 is ensured, the raw material gas is fully contacted with the metal lining 27 and the supported catalyst 29, the catalytic effect is improved, the length of the cracking reactor 10 is reduced, and the cost is reduced. After the reaction is finished, continuously introducing nitrogen into the cracking reactor 10 to remove residual R143a and 1, 1-difluoroethylene, preventing the residues from remaining in the cracking reactor 10 to be deeply cracked and carbonized, and accumulating for a long timeWhich can affect the life of the catalyst. The mixed gas after reaction is discharged from the bottom of the cracking reactor 10, enters the condenser 32 from the top of the condenser 32, condensate passes through the spiral pipe 36 in the condenser 32 in a low-inlet high-outlet mode, a low-temperature environment is formed in the inner cavity of the condenser 32, the mixed gas is cooled, the cooled mixed gas is discharged from the bottom, the cooling range of the condensate is large, the rapid cooling is realized, the cooling effect is good, the cooling liquid can use water, the source is wide, the cost is low, and the cooling liquid can be reused.
(c) Removing impurities: the dryer 34 is internally provided with an adsorption plate 37 and a drying box 38, the drying box 38 divides the inner space of the dryer 34 into an upper independent area and a lower independent area, the adsorption plate 37 is longitudinally and alternately distributed above the drying box 38, the surface of the adsorption plate 37 is provided with color-changing silica gel 39, the bottom of the drying box 38 is provided with a flow guide 40, the side wall of the flow guide 40 is provided with a flow dividing hole 41, the top surface of the drying box 38 is provided with a flow through hole 42, the flow through hole 42 and the flow dividing hole 41 are both communicated with the inner cavity of the drying box 38, and the inner cavity of the drying box 38 is provided with soda lime 43. The dust-removing filter screen 44 is arranged at the inner top of the dryer 34, and as the reaction proceeds, some particle impurities such as activated carbon particles, metal particles, soda lime 43 particles and the like are generated in the system, and the dust-removing filter screen 44 intercepts the particle impurities, so that the collection purity of the 1, 1-difluoroethylene can be improved.
The cooled mixed gas enters the alkaline washing tower 33 for deacidification, HF in the mixed gas is removed, the deacidified gas enters the dryer 34 from the bottom, only enters the guide pipe 40, then enters the inner cavity of the drying box 38 from the flow dividing hole 41, is divided into multiple small strands, the flow velocity is reduced, the residence time in the drying box 38 is prolonged, the gas is forced to contact with the soda lime 43, and the water absorption effect is improved. The gas after the primary water absorption flows out from the circulation holes 42, is split again, the flow speed is continuously reduced, and gradually moves upwards along the bending channel formed between the upper and lower adsorption plates 37, continuously contacts with the allochroic silica gel 39 on the surface of the adsorption plate 37, and is dehydrated again, and the flow path is long, so that the water removal effect is good. In the drying process, the sufficient contact area and contact time of the mixed gas and the water absorbent are ensured, the water absorption is more sufficient, the water in the mixed gas is effectively removed through the secondary water absorption effect, and the purity of the collected 1, 1-difluoroethylene is improved. The gas after secondary dehydration is discharged from the top of the dryer 34 and enters a collecting bag 35 for collection, and 1, 1-difluoroethylene is obtained.
The above is only a specific embodiment of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions or modifications and the like made on the basis of the present invention to solve the substantially same technical problems and achieve the substantially same technical effects are included in the scope of the present invention.
Claims (6)
1. A process for preparing 1, 1-difluoroethylene by R143a, comprising the steps of: (a) preparation: preparing a supported catalyst; (1) firstly, loading a supported catalyst into a fixing groove of a carrier plate, and then clamping a grid plate in the fixing groove to limit the grid plate on the carrier plate; (2) the carrier plate is arranged on a separation frame, and then the separation frame is arranged in a metal lining of the cracking reactor, so that the separation frame separates the inner space of the cracking reactor; (3) the positioning column on the side surface of the sealing cover passes through the positioning through hole on the positioning base on the side surface of the cracking reactor until the fixing ring on the cracking reactor is abutted against the outer edge of the sealing cover, and then the stroke cylinder is started, and the stroke cylinder drives the stop plate to pass through the stop through hole on the positioning column through the fixing plate, so that the sealing cover is limited and fixed on the cracking reactor; (4) connecting the reactors through pipelines; an electric heater is arranged on the inner bottom surface of the cracking reactor, a fixed ring and a fixed support are arranged outside the cracking reactor, a travel cylinder is arranged on the fixed support, a fixed plate is arranged at the output end of the travel cylinder, a stop plate is arranged on the fixed plate, a positioning base is arranged on the fixed ring, a positioning through hole is arranged on the positioning base, a positioning column corresponding to the positioning through hole is arranged on the side surface of the sealing cover, and a stop through hole corresponding to the stop plate is arranged on the positioning column; the separation frame comprises a central shaft, a first separation plate, a second separation plate and a third separation plate, wherein the first separation plate, the second separation plate and the third separation plate are distributed on the central shaft in a surrounding mode, the top surface of the first separation plate is flush with the top surface of the second separation plate, the top surface of the second separation plate is higher than the top surface of the third separation plate, the bottom surface of the first separation plate is flush with the bottom surface of the third separation plate, the bottom surface of the second separation plate is higher than the bottom surface of the third separation plate, trapezoidal clamping grooves are formed in the first separation plate, the second separation plate and the third separation plate, and one end of each trapezoidal clamping groove is closed and one end of each trapezoidal clamping groove is open; a metal lining is arranged in the cracking reactor, an inner clamping groove corresponding to the first baffle plate, the second baffle plate and the third baffle plate is formed in the metal lining, and a pressing block for pressing the center shaft is arranged on the inner bottom surface of the sealing cover; (b) cleavage: (1) turning on the preheater and the electric heaters in the cracking reactor, introducing raw material gas R143a into the preheater for preheating, and introducing nitrogen into the cracking reactor for purging to remove air in the cracking reactor; (2) preheating raw material gas, introducing the preheated raw material gas into a cracking reactor for cracking reaction, and cooling the reacted mixed gas in a condenser; (c) removing impurities: the cooled mixed gas enters an alkaline washing tower for deacidification, and the deacidified gas enters a dryer for dehydration, and the specific method for drying is as follows: the deacidified gas enters a dryer from the bottom, enters a drying box filled with soda lime from a diversion hole on the side wall of a diversion pipe for dehydration, flows out from a circulation hole on the top surface of the drying box, gradually rises between adsorption plates distributed in a staggered way up and down, continuously contacts with allochroic silica gel on the surfaces of the adsorption plates, is dehydrated again, and is discharged from the top; the dryer is internally provided with an adsorption plate and a drying box, wherein the adsorption plate is longitudinally and alternately distributed above the drying box, the surface of the adsorption plate is provided with color-changing silica gel, the bottom of the drying box is provided with a guide pipe, the side wall of the guide pipe is provided with a flow dividing hole, the top surface of the drying box is provided with a flow through hole, the flow through hole and the flow dividing hole are both communicated with the inner cavity of the drying box, and the inner cavity of the drying box is filled with soda lime; the dehydrated gas enters a collecting bag for collection to obtain the 1, 1-difluoroethylene.
2. A process for preparing 1, 1-difluoroethylene from R143a as claimed in claim 1, wherein: the inner top of the dryer is provided with a dust removing filter screen.
3. A process for preparing 1, 1-difluoroethylene from R143a as claimed in claim 1, wherein: the specific practice of cooling in step (c) is as follows: the mixed gas enters the condenser from the top, condensate liquid passes through the spiral pipe in the condenser in a low-inlet and high-outlet mode, a low-temperature environment is formed in the inner cavity of the condenser, the mixed gas is cooled, and the cooled mixed gas is discharged from the bottom.
4. A process for preparing 1, 1-difluoroethylene from R143a as claimed in claim 1, wherein: the preparation process of the supported catalyst in the step (a) comprises the following steps: the sheet active carbon is boiled and washed by nitric acid for 1-2h, then is washed to be neutral by deionized water, is immersed in metal chloride solution for 8-10h, is filtered and is dried in a drier at 100-110 ℃ for 8-10h for standby.
5. A process for preparing 1, 1-difluoroethylene from R143a as claimed in claim 1, wherein: in the step (a), the trapezoid strakes of the carrying plate are clamped into the trapezoid clamping grooves on the separation frame in the step (2), so that the carrying plate is limited on the separation frame, and the outer side edge of the separation frame is clamped into the inner clamping grooves on the metal lining, so that the separation frame is limited in the cracking reactor.
6. A process for preparing 1, 1-difluoroethylene from R143a as claimed in claim 1, wherein: the reaction temperature of the cracking reactor in the step (b) is 200-500 ℃, the reaction pressure is normal pressure, and the space velocity is 50-250h -1 。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202210001799.0A CN114292157B (en) | 2022-01-04 | 2022-01-04 | Method for preparing 1, 1-difluoroethylene by using R143a |
Applications Claiming Priority (1)
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| US3456025A (en) * | 1965-12-03 | 1969-07-15 | Phillips Petroleum Co | Preparation of difluoroalkenes |
| CN204093428U (en) * | 2014-10-09 | 2015-01-14 | 李灏呈 | Manifold type catalyst for denitrating flue gas reaction unit |
| CN110776394A (en) * | 2019-11-07 | 2020-02-11 | 上海三爱富新材料科技有限公司 | Method for preparing fluorine-containing ethylene by catalytic cracking of 2-chloro-1, 1-difluoroethane |
| CN213865373U (en) * | 2020-10-27 | 2021-08-03 | 贵州瓮福开磷氟硅新材料有限公司 | Dehydration and desulfurization device for producing anhydrous hydrogen fluoride by using phosphoric acid byproduct fluosilicic acid |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US3456025A (en) * | 1965-12-03 | 1969-07-15 | Phillips Petroleum Co | Preparation of difluoroalkenes |
| CN204093428U (en) * | 2014-10-09 | 2015-01-14 | 李灏呈 | Manifold type catalyst for denitrating flue gas reaction unit |
| CN110776394A (en) * | 2019-11-07 | 2020-02-11 | 上海三爱富新材料科技有限公司 | Method for preparing fluorine-containing ethylene by catalytic cracking of 2-chloro-1, 1-difluoroethane |
| CN213865373U (en) * | 2020-10-27 | 2021-08-03 | 贵州瓮福开磷氟硅新材料有限公司 | Dehydration and desulfurization device for producing anhydrous hydrogen fluoride by using phosphoric acid byproduct fluosilicic acid |
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