WO2024198134A1

WO2024198134A1 - Method for preparing electronic-grade octafluoropropane

Info

Publication number: WO2024198134A1
Application number: PCT/CN2023/104883
Authority: WO
Inventors: 黄媛玲; 周文平; 张前臻
Original assignee: 福建德尔科技股份有限公司
Priority date: 2023-03-27
Filing date: 2023-06-30
Publication date: 2024-10-03
Also published as: CN116283479B; CN116283479A

Abstract

The present invention belongs to the field of chemical synthesis, and particularly relates to a method for preparing electronic-grade octafluoropropane. The method comprises: 1) arranging a transparent tubular reaction container containing a CTN catalyst, arranging the CTN catalyst on a reaction raw material flowing path, and raising the temperature of the reaction container and the CTN catalyst for preheating until a reaction temperature is reached; and 2) applying illumination to the reaction container and simultaneously electrifying the CTN catalyst to carry out dual excitation on the CTN catalyst, introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container, and after the reaction gas reacts, obtaining the electronic-grade octafluoropropane. The present invention can achieve direct conversion preparation of propane to perfluoropropane, the raw material utilization rate can be stably maintained at 97% or higher, and the reaction process is simple, safe and efficient, so that the present invention has significant advantages in improving the safety of production and preparation and reducing energy consumption, thereby having popularization value.

Description

A method for preparing electronic grade octafluoropropane

Technical Field

The invention belongs to the field of chemical synthesis, and in particular relates to a method for preparing electronic grade octafluoropropane.

Background Art

Electronic grade octafluoropropane is an organic compound with the molecular formula C ₃ F ₈ , which is the product of propane being completely replaced by fluorine atoms. It has a wide range of applications in plasma etching, surface treatment, and low-temperature refrigeration in microelectronics. Especially in the semiconductor manufacturing process, electronic grade octafluoropropane, as an etching gas, is an important material for constructing semiconductor circuit patterns.

At present, electronic grade octafluoropropane is largely dependent on imports, and there are few domestic companies that can effectively mass-produce it. The main reason is that its preparation is difficult and costly, resulting in low overall production and preparation cost-effectiveness.

Traditional methods for preparing electronic-grade octafluoropropane include the composite reaction of trifluoropentachloropropane and manganese trifluoride, the electrolytic fluorination reaction of chloropropane, the fluorination reaction of propylene, and the direct fluorination reaction of carbon. However, these preparation methods will produce a large amount of impurities. Even from the perspective of product yield, electronic-grade octafluoropropane is a "by-product" in some processes, and its product yield is only about 20%. It needs to be processed with a large number of impurity removal and purification processes to finally obtain a relatively small amount of electronic-grade octafluoropropane components. It can be seen that the reaction selectivity of the material is extremely low. Among them, the only process that can achieve a high conversion rate and high product purity is the hexafluoropropylene step-by-step addition method. In this method, hexafluoropropylene reacts with hydrogen fluoride under the action of a catalyst to produce an intermediate reaction product 2H-heptafluoropropane (CF ₃ CHFCF ₃ ), and then further reacts with excess fluorine gas under high temperature conditions with a strong catalyst to achieve a high conversion rate of heptafluoropropane to electronic-grade octafluoropropane, and after separation and distillation, electronic-grade octafluoropropane with high purity can be obtained. The overall process flow is complicated, the hexafluoropropylene raw material procurement cost is also relatively expensive, the stability under gaseous conditions is poor, and it is difficult to store for a long time. The overall process is difficult to implement and the cost is high. The multi-step high-temperature reaction leads to high energy consumption and great safety hazards. In the reaction process, fluorine gas has a great obstacle to the fluorination of 2°C in heptafluoropropane.

In summary, it can be found that the existing processes cannot directly carry out propane fluorination, and most of them need to be carried out under high temperature and/or high pressure conditions. The resulting product will inevitably contain more impurities, which are difficult to separate or effectively process.

Technical issues

In order to solve the problems that the existing electronic grade octafluoropropane preparation process requires high temperature and/or high pressure, and even liquefaction for liquid phase reaction and other harsh conditions, and the reaction process has poor selectivity, high impurity content in the obtained product, and subsequent impurity removal and purification process is relatively difficult, the present invention provides a method for preparing electronic grade octafluoropropane.

The main purpose of the present invention is:

1. It can realize the direct conversion preparation of propane to electronic grade octafluoropropane;

Second, the reaction has strong selectivity and can effectively obtain the desired product;

3. It can avoid the use of high temperature and high pressure conditions, improve the safety of the reaction and reduce energy consumption;

4. Ensure high utilization rate of raw materials to improve industrial benefits.

Technical Solutions

To achieve the above objectives, the present invention adopts the following technical solutions.

A method for preparing electronic grade octafluoropropane,

The method comprises:

1) a transparent tubular reaction vessel containing a CTN catalyst is provided, the CTN catalyst is provided on a flow path of the reaction raw materials, and the reaction vessel and the CTN catalyst are preheated to reach a reaction temperature;

2) applying light to the reaction container and simultaneously applying electricity to the CTN catalyst to perform dual excitation on the CTN catalyst, and introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container, and obtaining electronic grade octafluoropropane after the reaction of the reaction gas.

As a preference,

Step 1) The CTN catalyst is a C-Ti-Ni-O catalyst, which contains elemental carbon as a skeleton and is doped and coated with Ni(II) and Ti(IV) oxides, as well as Ni(III) oxides and/or NSO.

As a preference,

The CTN catalyst is a porous composite membrane material, which is composed of several single-layer porous membrane structures;

The single-layer porous membrane structure has a two-dimensional structure similar to a honeycomb grid.

As a preference,

Step 1) The reaction temperature is 90-105°C.

As a preference,

Step 2) The lighting control conditions are:

The laser light source is 380-420 nm in wavelength and 3.0-3.6 μmol/(m ² ·s) in light quantum density.

Step 2) The power-on control condition is:

Connect the electrode sheet to the CTN catalyst and connect it to the power supply to build an electrical circuit, and control the current to be 25-40 mA;

The CTN catalyst has a negative electrode sheet attached to the side facing the air inlet end of the reaction container, and a positive electrode sheet attached to the side facing the air outlet end.

As a preference,

The ratio of propane in the reaction gas to fluorine atoms in the electrophilic fluorinating agent is 1:(8-10).

As a preference,

The electrophilic fluorinating agent is mixed with 7 to 12 times of nitrogen and then mixed with propane to form a reaction gas.

As a preference,

Step 2) The reaction gas is controlled at a flow rate of 0.1-0.2 RV/min.

The present invention is mainly based on a novel photocatalytic CTN material developed by the applicant, which is composed of a plurality of layers of a single-layer two-dimensional membrane structure, and the typical morphology of the single-layer membrane structure characterized by SEM is shown in Figure 1. The characterization results show that the catalyst monolayer of the present invention presents a relatively regular honeycomb grid-like porous structure with a pore size of approximately 20 to 60 μm.

In addition, the element characterization and TAP characterization of the CTN catalytic material show that the present invention clearly has a C skeleton structure, as well as metal components mainly composed of Ti(IV) and Ni(II), containing a small amount of Ni(III), and based on the oxygen content characterization results, the relative relationship between Ti(IV), Ni(II) and Ni(III), it can be determined that NSO exists in the catalytic material of the present invention. In addition, according to the calculation of Ni(II), Ni(III) and the remaining O, it basically meets the composition of Ni _0.92 O.

Based on the above CTN catalyst combined with practical use and performance research, its utility in the preparation of electronic grade octafluoropropane is maximized.

Therefore, based on this, the CTN material for which the invention patent has also been applied for is first described. For the present invention (including the subsequent embodiments), the CTN catalytic material used is prepared by the following process:

1) Titanium nitrate, nickel nitrate, terephthalic acid and N,N-dimethylformamide were mixed and taken in proportion, and 1 molar equivalent (Eq) of titanium nitrate, 1 molar equivalent (Eq) of nickel nitrate and 0.25 molar equivalent (Eq) of terephthalic acid were weighed as raw materials respectively, and 5 wt% of ammonium molybdate tetrahydrate as a catalyst was added to the raw materials, and an excess amount (5 molar equivalents, i.e., 5 Eq) of DMF was taken as a reaction solvent, and after stirring at 120 rpm for 30 min, the mixture was reacted at 7 MPa and 180 °C for 16 h to obtain a white transparent film precursor;

The actual amount is calculated according to the actual product demand. For example, if 1 molar equivalent is set to 2 mol, 592 g of titanium nitrate [Ti(NO ₃ ) ₄ ], 365 g of nickel nitrate [Ni(NO ₃ ) ₂ ], 83 g of terephthalic acid and 1550 mL of DMF, and 52 g of ammonium molybdate tetrahydrate are weighed respectively;

2) The film precursor obtained in step 1) is spread out and placed in a vacuum condition at 60 ° C for 12 h for desolvation, and then annealed at 325 ° C for 2 h in a nitrogen atmosphere. Finally, the temperature is raised to 220 ° C for reaction for 3 h in a 2.0 MPa nitrogen and oxygen mixture (oxygen partial pressure is 0.2 MPa) to obtain a catalytic material for the preparation of electronic grade octafluoropropane.

Based on the above, the present invention further adjusts the use method and conditions of the CTN catalyst. In the original research plan, the selectivity of the CTN catalyst for propane perfluorination was found, which can be simply achieved under light excitation conditions. Specifically, the reaction process is roughly as follows: Where: for and/or , For the environment deprotonation medium, e.g. and , formed by Hydronium ion or protonated dinitrogen , For electrophilic fluorinating agents, such as or etc., that is for or In the above process, the photoexcited titanium dioxide first forms photoexcited electrons and valence band holes, which is the basis for realizing the chain reaction. However, in the actual catalytic experiment, it was found that the single electron oxidation process and the NSO catalytic dehydrogenation process in the catalytic process could not reach a balance, which led to the fact that some heptafluoropropane could not be effectively converted into electronic grade octafluoropropane. The main reason was that the intermediate 1,1,1,3,3-pentafluoropropane The generation rate of is too fast, which leads to the obstruction of the 2°C dehydrogenation process. In the continuous experiment process, only by adjusting multiple conventional reaction variables under photoexcitation conditions, only about 99.3% of the raw material conversion rate and about 81% of the electronic grade octafluoropropane yield can be obtained (calculated only based on the reaction products after removing propane).

The present invention has found in continuous excitation tests that, under power-on conditions, the reaction efficiency of the NSO catalytic dehydrogenation process is significantly improved, but impurity components such as CO ₂ , CF ₂ =CHF and C ₂ H _x F _y (x+y=6) are found in the reaction products, indicating that the NSO catalytic dehydrogenation reaction is too fast to cause certain cracking. Therefore, the present invention has achieved an overall equilibrium trend of single-electron oxidation and NSO catalytic dehydrogenation through continuous testing and adjustment of parameters.

Under the dual excitation conditions of light excitation and electrical excitation, the researchers believe that the photoexcited electrons of titanium dioxide are still the first First, the NSO catalytic dehydrogenation reaction is initiated by excitation, but under the condition of light excitation only, the generated The 2°C dehydrogenation reaction of propane and/or propane fluoride catalyzed by NiO-NSO is insufficient to fully drive the reaction. This may be due to the material's inherent conductivity and the photoexcited electron migration mechanism. For example, factors such as hole adsorption and photoexcited electron confinement sites have a significant impact on the photoexcited electron migration mechanism. The migration of electrons is affected, and under the condition of power supply, the migration efficiency of electrons is improved, so that the catalytic dehydrogenation reaction of NSO can be strengthened. However, it should also be noted that when the current is too large, the photocatalytic activity of titanium dioxide is prone to decrease. The researchers believe that the power supply may inhibit the process of photoelectrons exciting titanium dioxide to produce valence band holes and photoexcited electrons to a certain extent.

Therefore, from the perspective of considering the reaction products and controlling the two catalytic processes to maintain a certain proportional balance, for the present invention, the control of light intensity and current size is very critical.

Beneficial Effects

The beneficial effects of the present invention are:

The present invention can realize the direct conversion preparation of propane into perfluoropropane, and the raw material utilization rate can be stably maintained at more than 97%, and the reaction process is simple, safe and efficient, which has significant advantages in improving the safety of production and preparation and reducing energy consumption, and has promotion value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a typical single-layer structure of a CTN catalyst used in the present invention;

FIG2 is a schematic flow diagram of the method of the present invention;

FIG3 is a schematic diagram of the assembly of the CTN catalyst of the present invention;

In the figure: 100 reaction tube, 200 CTN catalyst, 300 power supply, 301 negative electrode plate, 302 positive electrode plate.

Embodiments of the present invention

The present invention is further described in detail below in conjunction with specific embodiments and the accompanying drawings. A person of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are generally only embodiments of a part of the present invention, rather than all embodiments. Therefore, based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without making creative work should fall within the scope of protection of the present invention.

In the description of the present invention, it should be understood that the terms "thickness", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined, and "several" means one or more.

In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all methods known to those skilled in the art.

Embodiment: The reaction process and CTN catalyst are arranged as shown in Figures 2 and 3. Specifically, the CTN catalyst is stacked in sheets in a reaction tube, and the length of the stacked section accounts for one third of the total length. The air inlet and air outlet ends of the reaction tube are determined. As shown in Figure 3, a negative electrode plate is attached to the air inlet end of the stacked CTN catalyst, and a positive electrode plate is attached to the other side toward the air outlet end. The positive electrode plate and the negative electrode plate are connected to an external controllable power supply.

Specifically, the present invention is described below by controlling reaction parameters.

Embodiment: A method for preparing electronic grade octafluoropropane, which specifically comprises the following steps:

1) a transparent tubular reaction vessel containing a CTN catalyst is provided, the CTN catalyst is provided on a flow path of the reaction raw materials, and the reaction vessel and the CTN catalyst are preheated to a reaction temperature of 95°C;

2) Applying light to the reaction container and simultaneously applying power to the CTN catalyst to perform dual excitation of the CTN catalyst, using a laser light source to control the light wavelength to 390 nm and the light quantum density to 3.2 μmol/(m ² ·s), controlling the power-on current to 30 mA, and introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container. The reaction gas is a propane gas and fluorine-nitrogen mixture gas in a volume ratio of 1:80, the volume proportion of fluorine gas in the fluorine-nitrogen mixture gas is 10%, and the reaction gas flow rate is controlled to 0.15 RV/min (RV is Reaction tube volume). After the reaction of the reaction gas, electronic grade octafluoropropane is obtained.

The reaction products were characterized, and the raw material conversion rate and the product yield of electronic grade octafluoropropane were calculated.

The formula for calculating the raw material conversion rate is as follows: The product yield of electronic grade octafluoropropane is calculated as follows: Wherein: The theoretical maximum yield of electronic grade octafluoropropane in the reaction process is the molar amount of propane gas introduced before the reaction.

Based on the above, the raw material conversion rate of this embodiment is calculated to be 99.5%, and the product yield of electronic grade octafluoropropane is 93.3%.

Compared with the maximum yield of CTN under pure photocatalytic conditions (99.3%×81%≈80.4%), the yield is increased by about 16.0%, which is a very significant improvement, and the main impurities in the product are converted into _CO2 and _CF3CF3 , among which the boiling point of electronic grade octafluoropropane is -36.7℃, the boiling point of carbon dioxide is _-78.5 ℃, and the boiling point of hexafluoroethane is -78.2℃. Compared with heptafluoropropane, the process of the present invention produces less impurities, the yield and purity of the directly obtained electronic grade octafluoropropane are improved, and the impurity components are easier to remove, and the overall industrial feasibility and value are higher.

1) a transparent tubular reaction vessel containing a CTN catalyst is provided, the CTN catalyst is provided on a flow path of the reaction raw materials, and the reaction vessel and the CTN catalyst are preheated to a reaction temperature of 90°C;

2) Applying light to the reaction container and simultaneously applying power to the CTN catalyst to perform dual excitation of the CTN catalyst, using a laser light source to control the light wavelength to 380 nm and the light quantum density to 3.6 μmol/(m ² ·s), controlling the power-on current to 40 mA, and introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container. The reaction gas is a propane gas and fluorine-nitrogen mixture gas in a volume ratio of 1:80, and the volume proportion of fluorine gas in the fluorine-nitrogen mixture gas is 10%. The reaction gas flow rate is controlled to be 0.2 RV/min (RV is Reaction tube volume), and electronic grade octafluoropropane is obtained after the reaction of the reaction gas.

Based on the above, the raw material conversion rate of this embodiment is calculated to be 99.8%, and the product yield of electronic grade octafluoropropane is 94.1%.

1) a transparent tubular reaction vessel containing a CTN catalyst is provided, the CTN catalyst is provided on a flow path of the reaction raw materials, and the reaction vessel and the CTN catalyst are preheated to a reaction temperature of 105°C;

2) Applying light to the reaction container and simultaneously applying power to the CTN catalyst to perform dual excitation of the CTN catalyst, using a laser light source to control the light wavelength to 420 nm and the light quantum density to 3.2 μmol/(m ² ·s), controlling the power-on current to 30 mA, and introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container. The reaction gas is a propane gas and fluorine-nitrogen mixture gas in a volume ratio of 1:80, the volume proportion of fluorine gas in the fluorine-nitrogen mixture gas is 10%, and the reaction gas flow rate is controlled to 0.1 RV/min (RV is Reaction tube volume). After the reaction of the reaction gas, electronic grade octafluoropropane is obtained.

Based on the above, the raw material conversion rate of this embodiment is calculated to be 99.6%, and the product yield of electronic grade octafluoropropane is 94.2%.

Comparative Example 1

A method for preparing electronic grade octafluoropropane, which specifically comprises the following steps:

2) Applying light to the reaction container and simultaneously applying power to the CTN catalyst to perform dual excitation of the CTN catalyst, using a laser light source to control the light wavelength to 380 nm and the light quantum density to 3.6 μmol/(m ² ·s), controlling the power-on current to 50 mA, and introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container. The reaction gas is a propane gas and fluorine-nitrogen mixture gas in a volume ratio of 1:80, the volume proportion of fluorine gas in the fluorine-nitrogen mixture gas is 10%, and the reaction gas flow rate is controlled to 0.2 RV/min (RV is Reaction tube volume). After the reaction of the reaction gas, electronic grade octafluoropropane is obtained.

Based on the above, it is calculated that the raw material conversion rate of this embodiment is greater than 99.9%, and the product yield of electronic grade octafluoropropane is 86.6%.

Comparative Example 2

2) Applying light to the reaction container and simultaneously applying power to the CTN catalyst to perform dual excitation of the CTN catalyst, using a laser light source to control the light wavelength to 380 nm and the light quantum density to 3.6 μmol/(m ² ·s), controlling the power-on current to 20 mA, and introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container. The reaction gas is a propane gas and fluorine-nitrogen mixture gas in a volume ratio of 1:80, the volume proportion of fluorine gas in the fluorine-nitrogen mixture gas is 10%, and the reaction gas flow rate is controlled to 0.2 RV/min (RV is Reaction tube volume). After the reaction of the reaction gas, electronic grade octafluoropropane is obtained.

Based on the above, the raw material conversion rate of this embodiment is calculated to be 98.9%, and the product yield of electronic grade octafluoropropane is 79.7%.

Through the experimental analysis of the above examples 1 to 3, it can be seen that the technical solution of the present invention is very effective in the development of CTN catalysts, which significantly improves the use effect of CTN catalysts, and the overall process solution has great value. By comparing the comparative examples 1 to 2, it can be found that when the current size is excessively increased or reduced, the product yield of electronic grade octafluoropropane is significantly reduced.

For Comparative Example 1, its product was characterized, and the characterization results showed that the main composition of impurities in its product was similar to that of Examples 1 to 3, mainly cracking products of fluoropropane, mainly including carbon dioxide, hexafluoroethane and other components. At the same time, pentafluoroethane, 1,1,1,3-tetrafluoroethane and other components were also produced. The production of such impurity components also fully confirmed the researchers' view that the application of current is not conducive to the photocatalytic process of titanium dioxide. The efficiency of hydrogen atoms being replaced by fluorine atoms at 1°C is significantly reduced, and the single-electron oxidative fluorination process is significantly hindered. The product characterization results of Comparative Example 2 are relatively close to the CTN photocatalytic conditions. The original content of impurity components such as carbon dioxide and hexafluoroethane is significantly reduced or even basically undetected, but the impurity content of heptafluoropropane is significantly increased, indicating that too low a current is not conducive to the process of realizing photoelectric catalysis by dual excitation of the present invention.

Claims

A method for preparing electronic grade octafluoropropane, characterized in that the method comprises:

1) a transparent tubular reaction vessel containing a CTN catalyst is provided, the CTN catalyst is provided on a flow path of the reaction raw materials, and the reaction vessel and the CTN catalyst are preheated to reach a reaction temperature;

2) applying light to the reaction container and simultaneously applying electricity to the CTN catalyst to perform dual excitation on the CTN catalyst, and introducing a reaction gas containing propane and an electrophilic fluorinating agent into the reaction container, and obtaining electronic grade octafluoropropane after the reaction of the reaction gas.
The method for preparing electronic grade octafluoropropane according to claim 1, characterized in that:

Step 1) The CTN catalyst is a C-Ti-Ni-O catalyst, which contains elemental carbon as a skeleton and is doped and coated with Ni(II) and Ti(IV) oxides, as well as Ni(III) oxides and/or NSO.
A method for preparing electronic grade octafluoropropane according to claim 2, characterized in that the CTN catalyst is a porous composite membrane material, which is composed of a plurality of single-layer porous membrane structures; the single-layer porous membrane structure has a two-dimensional structure similar to a honeycomb grid.
The method for preparing electronic grade octafluoropropane according to claim 1, characterized in that:

Step 1) The reaction temperature is 90-105°C.
The method for preparing electronic grade octafluoropropane according to claim 1, characterized in that:

Step 2) The lighting control conditions are:

The laser light source is 380-420 nm in wavelength and 3.0-3.6 μmol/(m 2 ·s) in light quantum density.

Step 2) The power-on control condition is:

Connect the electrode sheet to the CTN catalyst and connect it to the power supply to build an electrical circuit, and control the current to be 25-40 mA;

The CTN catalyst has a negative electrode sheet attached to the side facing the air inlet end of the reaction container, and a positive electrode sheet attached to the side facing the air outlet end.
The method for preparing electronic grade octafluoropropane according to claim 1, characterized in that:

The ratio of propane in the reaction gas to fluorine atoms in the electrophilic fluorinating agent is 1:(8-10).
A method for preparing electronic grade octafluoropropane according to claim 1 or 6, characterized in that:

The electrophilic fluorinating agent is mixed with 7 to 12 times of nitrogen and then mixed with propane to form a reaction gas.
The method for preparing electronic grade octafluoropropane according to claim 1, characterized in that:

Step 2) The reaction gas is controlled at a flow rate of 0.1-0.2 RV/min.