CN112225637B - One-step method for preparing methane chloride - Google Patents
One-step method for preparing methane chloride Download PDFInfo
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- CN112225637B CN112225637B CN202011083083.7A CN202011083083A CN112225637B CN 112225637 B CN112225637 B CN 112225637B CN 202011083083 A CN202011083083 A CN 202011083083A CN 112225637 B CN112225637 B CN 112225637B
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- C07—ORGANIC CHEMISTRY
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- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
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Abstract
The invention discloses a method for preparing methane chloride by a high-selectivity one-step method, which comprises the following steps: in a reactor, methane gas or methane-containing gas and chlorine salt as chlorine source are reacted at 0-100 deg.c for 10-600 min under light condition in the presence of copper doped titanium dioxide compound as catalyst. The method has high selectivity on the target product, namely the monochloromethane, almost has no polychlorinated methane by-products, and ensures that the chloromethane product after reaction has high purity and is easy to separate. Moreover, the method has the advantages of simple reaction process, short period, mild reaction conditions, cheap and easily-obtained catalyst, reusability, wide source of reactant raw materials, low price and easy obtaining, and especially the capability of directly using natural gas or methane as raw material gas, and the like, provides a new synthesis way for preparing methane chloride products from methane-containing gases such as natural gas, shale gas or methane, and has wide industrial application prospect.
Description
Technical Field
The invention relates to a novel method for preparing methane chloride with high selectivity.
Background
The monochloromethane is used as an important chemical raw material, can be used for producing tetramethylchlorosilane, methylcellulose, quaternary ammonium compounds and the like, can be widely used as a solvent, an extracting agent and a methylation reagent, and plays an important role in the industries of construction, textile, electronics, electrical appliances, machinery, traffic, chemical industry, medical food, aviation, aerospace and the like. At present, methane chlorination method and methanol hydrochlorination method are commonly adopted for industrially generating methane chloride. However, both of these methods require high temperature and are prone to generate by-products such as dichloromethane, dimethyl ether, etc., and the selectivity of monochloromethane is not good, so that further separation and purification are required after the reaction, which leads to an increase in production cost.
In view of the cost of industrial production and the problems of energy crisis and environmental pollution, there is a need in the art for a new method for preparing monochloromethane with more greenness, simple reaction process, mild reaction conditions and high selectivity.
Disclosure of Invention
In view of the above, it is an object of the present invention to provide a green novel process for the preparation of monochloromethane with high selectivity under mild conditions.
To this end, the present invention provides a one-step process for the preparation of monochloromethane, the process comprising: in a reactor, methane gas or methane-containing gas and chlorine salt as a chlorine source are reacted at a reaction temperature of 0 to 100 ℃ for 10 to 600min under a light condition in the presence of a copper-doped titanium dioxide compound as a catalyst.
In a preferred embodiment, the methane-containing gas is natural gas, shale gas, combustible ice or biogas.
In a preferred embodiment, the chloride salt is one or more selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, magnesium chloride and seawater crystalline (salt).
In a preferred embodiment, the atomic molar ratio of copper to titanium in the catalyst is from 0.005 to 0.1: 1.
In a preferred embodiment, the illumination intensity of the illumination conditions is from 10 to 2000mW/cm2。
In a preferred embodiment, the light source used for the lighting conditions is one or more selected from a xenon lamp, an LED lamp, a tungsten lamp, and a mercury lamp.
In a preferred embodiment, the reaction temperature is 20-60 ℃ and the reaction time is 100-.
In a preferred embodiment, the reactor is a quartz reactor, a glass reactor or a fixed bed reactor.
In a preferred embodiment, the pressure of the methane gas or methane-containing gas in the reactor is between 0.1MPa and 10 MPa.
In a preferred embodiment, the mass ratio of the catalyst to the chloride salt is 0.01-0.5: 1.
The method of the invention uses chloride salt as chlorine source and uses specific doped catalyst to react under the condition of illumination, and the photocatalytic reaction can make methyl radical (CH) formed in the reaction process3) Stable so that almost no polychlorinated methane is produced as a by-product, thereby having high selectivity (over 70% and even up to 90% overall) to the target product, methyl chloride, and allowing easy separation of the target product after reaction.
The method has the advantages of simple reaction process, short period, mild reaction condition, cheap and easily-obtained catalyst, reusability, wide source of reactant raw materials, low price and easy obtaining, and especially can directly use natural gas or methane as the raw materials, and the like, not only can realize the high-selectivity preparation of methane chloride under mild condition, reduce industrial generation process and cost, but also can greatly relieve the problems of energy crisis and environmental pollution.
In addition, the invention provides a new synthesis way for preparing the methane chloride product from methane-containing gases such as natural gas or methane, and the like, and has wide industrial application prospect.
Drawings
FIG. 1 is a Gas Chromatography (GC) graph of a methyl chloride product obtained according to one embodiment of the present invention.
Fig. 2 is a graph showing the effect of reusing a copper-doped titanium dioxide compound as a catalyst according to the present invention.
Detailed Description
As a result of intensive and extensive studies by the inventors of the present invention, a novel process for producing monochloromethane by using a chlorine salt as a chlorine source and reacting under light irradiation conditions using a specific doped catalyst, which photocatalytic reaction allows formation of methyl radicals (. CH.) during the reaction3) Stable, so that almost no polychlorinated methane by-product is produced, thereby not only realizing the preparation of the monochloromethane by one step with high selectivity under mild conditions, but also greatly relieving the energy crisis and the environmental pollution problem in a simple and cost-effective way.
The one-step method for preparing the methane chloride comprises the following steps: in the reactor, methane gas or a methane-containing gas is reacted with a chlorine salt as a chlorine source at a reaction temperature of 0 to 100 ℃ for 10 to 600min under light conditions using a copper-doped titanium dioxide compound as a catalyst, whereby methane in the methane gas or the methane-containing gas is converted into methyl chloride with high selectivity.
In the process of the present invention, the monochloromethane product can be separated after the reaction is complete by conventional means, such as, but not limited to, separation based on boiling point differences (boiling point of the desired product monochloromethane is about-23.7 ℃, boiling point of the starting methane is about-161.5 ℃, and boiling point of the possible by-product ethane is about-88.6 ℃), and the target product monochloromethane can be separated by pressure liquefaction as is well known in the art.
In the process of the invention, the product, methyl chloride, and its selectivity, can be determined by conventional means, such as, but not limited to, the use of gas chromatography, GC, after the reaction is complete.
In the process of the invention, preferably, as chlorine source, the chlorine salt used may be sodium chloride NaCl, potassium chloride KCl, lithium chloride LiCl, magnesium chloride MgCl2And commercially available seawater crystalline (salt).
In the process of the invention, the catalyst used is copper (Cu) -doped titanium dioxide (TiO)2) A compound (i.e., a "copper-doped titanium dioxide compound"). In the catalyst of the present invention, titanium dioxide as a base material is not only widely available and inexpensive, but also has very excellent optical properties, chemical stability, thermal stability, super-hydrophilicity and non-migratory properties. Meanwhile, the inventors have found that a copper-doped titanium dioxide compound obtained by simply doping inexpensive copper can be used as a highly efficient catalyst for converting methane in methane gas or methane-containing gas into methyl chloride with high selectivity under specific reaction conditions in the production process of titanium dioxide. Furthermore, the inventors have found that such doped catalysts can be recovered after use by simple separation and can be reused many times with roughly equivalent efficiency, thereby making the overall process of the present invention extremely promising for industrial applications.
In the method of the present invention, preferably, in the catalyst, the atomic molar ratio of copper to titanium is 0.005 to 0.1: 1. It is to be noted here that, in the catalyst used in the present invention, copper (Cu) used for doping may be in the form of metallic copper, may also be in the form of copper oxide such as CuO, or the like. Applicants have found that in such atomic molar ratio ranges, the catalyst has a higher catalytic efficiency.
In the process of the present invention, the feed gas used may be in the form of a pure methane gas or a methane-containing gas. The term "methane-containing gas" refers to a gas mixture containing methane therein, preferably a methane-containing gas having a methane content of greater than 50% by volume, such as, but not limited to, natural gas, shale gas, combustible ice, or biogas, and the like.
In the process of the present invention, although there is no particular limitation on the pressure of the methane gas or the methane-containing gas in the reactor, it is preferable that the pressure of the methane gas or the methane-containing gas in the reactor is from 0.1MPa to 10 MPa.
In the method of the present invention, preferably, the illumination condition used may have an illumination intensity of 10 to 2000mW/cm2。
In the method of the present invention, the light source used for the illumination condition is not particularly limited as long as it can emit light radiation. Preferably, the light source for the lighting conditions may be one or more selected from a xenon lamp, an LED lamp (i.e., a light emitting diode), a tungsten lamp, and a mercury lamp.
In the process of the present invention, the reaction temperature of the reactor is usually 0 to 100 ℃; preferably, the reaction temperature used may be 20-60 deg.C, most preferably the reaction is carried out at ambient temperature (i.e., about 25-30 deg.C). If desired, the reactor may be heated to the desired reaction temperature by conventional means, such as a water bath or oil bath.
In the method of the present invention, the reaction time is usually 10 to 600min from the viewpoint of efficiency, and more preferably the reaction time may be 100-480 min.
In the method of the present invention, the reactor to be used is not particularly limited as long as it can withstand a certain pressure and is a container that can be sealed, and for example, the reactor to be used may be a quartz reactor, a glass reactor, a fixed bed reactor, or the like.
In the method of the present invention, although the amount of the catalyst and the reactant aluminum source used is not particularly limited, preferably, the mass ratio of the catalyst to the chloride salt used may be 0.01 to 0.5: 1.
The present invention is further described with reference to the following embodiments, which are only some preferred embodiments of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily made by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Unless otherwise specified, all starting materials used in the present invention are not particularly limited in their source and are commercially available; meanwhile, the purity is not particularly limited, and analytical purification is preferably employed in the present invention.
The reaction or detection apparatus or device used in the present invention is not particularly limited as long as the object can be achieved, and any conventional apparatus or device known to those skilled in the art can be used.
Catalyst preparation
The catalyst (copper-doped titanium dioxide compound) used in the present invention was prepared as follows:
to a glass crystallization dish, 50mg of copper nitrate, 6.8mL of tetrabutyltitanate, 60mL of ethanol, 4.6mL of glacial acetic acid, and 4mL of concentrated hydrochloric acid were added, and mixed uniformly with a stirring rod. Then, the glass crystallization dish was put into an oven at 65 ℃ to be evaporated and dried for 8 hours to obtain a solid substance. Subsequently, the obtained glass crystallization dish having a solid matter was calcined in a muffle furnace at 450 ℃ for 5 hours. Finally, it was naturally cooled to room temperature, thereby obtaining a copper-doped titanium dioxide compound, which was examined by X-ray photoelectron spectroscopy and scanning electron microscope spectroscopy, and in which the molar content of metallic copper Cu atoms relative to titanium atoms was 1% (i.e., the atomic molar ratio of copper to titanium was 0.01: 1).
Based on the same procedure as described above, except that the amount of copper nitrate used was changed accordingly, copper-doped titanium dioxide compounds were obtained in which the molar contents of metallic copper Cu atoms relative to titanium atoms were 2% (i.e., the atomic molar ratio of copper to titanium was 0.02:1) and 5% (i.e., the atomic molar ratio of copper to titanium was 0.05:1), respectively.
Example 1
100mg of a copper-doped titanium dioxide compound (copper in it) was added to a quartz reactor (which was in controlled communication via a stainless steel valve and was capable of applying a maximum pressure of 20MPa)And titanium in an atomic molar ratio of 0.02:1) as a catalyst and 200mg of sodium chloride as a chlorine source, and introducing high-purity (purity greater than 99.9%) methane gas through a pressure reducing valve in a methane steel cylinder, and then sealing the reactor (the pressure in the reactor is about 0.2 MPa). At room temperature (about 25 ℃ C.), 200mW/cm using a xenon lamp as a light source2The reaction is carried out for 480min under the irradiation of the illumination intensity. The resulting methyl chloride product can be isolated using pressure liquefaction.
After the reaction was complete, a gas sample was taken and the product distribution was determined by gas chromatography, GC. The gas chromatography GC detection conditions are as follows: agilent 7890B GC, Ar carrier gas, FID detector, capillary column, column temperature 60 ℃. The product was determined by gas chromatography to be methyl chloride and had a selectivity of 90%. Figure 1 shows a Gas Chromatography (GC) diagram of the methyl chloride product obtained according to this example. It should be noted that, from the viewpoint of the production rate of the target product, the production rate of the obtained methyl chloride is 2.5mmol/g catalyst/h, and the method has the potential of industrial application.
Example 2
The specific reaction procedure and detection method were the same as in example 1 except that potassium chloride was used as the chlorine source instead of sodium chloride. The selectivity of the target product, namely methane chloride, is detected to be 94%.
Example 3
The specific reaction procedure and detection method were the same as in example 1 except that a copper-doped titanium dioxide compound in which the atomic molar ratio of copper to titanium was 0.01:1 was used as a catalyst. The selectivity of the target product, namely methane chloride, is 82 percent through detection.
Example 4
The specific reaction procedure and detection method were the same as in example 1 except that a copper-doped titanium dioxide compound in which the atomic molar ratio of copper to titanium was 0.05:1 was used as a catalyst. The selectivity of the target product, namely the methane chloride, is 90 percent through detection.
Example 5
The specific reaction process and detection method were the same as in example 1, except that an LED lamp was used as the light source instead of the xenon lamp. The selectivity of the target product, namely methane chloride, is 83 percent through detection.
Example 6
The specific reaction process and detection method were the same as in example 1 except that the reaction time was shortened to 120 min. The selectivity of the target product, namely methane chloride, is 73 percent through detection.
Example 7
The specific reaction process and detection method were the same as in example 1 except that the reaction time was shortened to 240 min. The selectivity of the target product, namely methane chloride, is 85 percent through detection.
Example 8
The specific reaction process and detection method were the same as in example 1 except that the reaction time was extended to 600 min. The selectivity of the target product, namely the chloromethane, is 93 percent through detection.
Example 9
The specific reaction process and detection method were the same as in example 1 except that the reaction was carried out by keeping the temperature of the reaction cell at 50 ℃ by heating in a water bath. The selectivity of the target product, namely the chloromethane, is 93 percent through detection.
Example 10
The specific reaction procedure and detection method were the same as in example 1 except that a natural gas containing methane (wherein the methane content was 85% by volume) was used instead of the high-purity methane gas. The selectivity of the target product, namely the methane chloride, is 72 percent through detection.
Example 11
The specific reaction process and detection method were the same as in example 1 except that methane-containing biogas (wherein the methane content by volume was 60%) was used instead of the high-purity methane gas. The selectivity of the target product, namely methane chloride, is detected to be 70%.
Examples 12 to 14
The specific reaction process and detection method were the same as in example 1 except that the catalyst recovered after separation by filtration and drying at 65 c from example 1 was used 1, 2, 3 and 4 times, respectively (i.e., reused 3 times). Fig. 2 is a graph showing the effect of the reuse of the catalyst of the present invention (selectivity distribution of the target product, methyl chloride), in which fig. 2, the abscissa is the number of times of the reuse of the catalyst, and the ordinate is the selectivity of the target product, methyl chloride. As can be seen from fig. 2, the catalytic efficiency (i.e., the selectivity of the target product) of the catalyst of the present invention is not significantly reduced after four times of repeated use.
The foregoing is a preferred form of the invention and has been described in some detail, but the invention is not limited to the specific embodiments described above. Modifications and variations which may occur to those skilled in the art without departing from the technical principles of the present invention are to be considered within the scope of the appended claims.
Claims (9)
1. A one-step process for the preparation of methyl chloride, the process comprising: in a reactor, in the presence of a copper-doped titanium dioxide compound as a catalyst, under the condition of illumination, methane gas or methane-containing gas and chlorine salt as a chlorine source react for 10-600 min at the reaction temperature of 0-100 ℃, wherein in the catalyst, the atomic molar ratio of copper to titanium is 0.005-0.1: 1.
2. The method of claim 1, wherein the methane-containing gas is natural gas, shale gas, combustible ice, or biogas.
3. The method of claim 1, wherein the chloride salt is one or more selected from the group consisting of sodium chloride, potassium chloride, lithium chloride, magnesium chloride, and seawater crystalline salts.
4. The method according to claim 1, wherein the illumination condition has an illumination intensity of 10 to 2000mW/cm2。
5. The method according to claim 4, wherein the light source for the illumination condition is one or more selected from a xenon lamp, an LED lamp, a tungsten lamp, and a mercury lamp.
6. The method as claimed in claim 1, wherein the reaction temperature is 20-60 ℃ and the reaction time is 100-.
7. The method of claim 1, wherein the reactor is a quartz reactor, a glass reactor, or a fixed bed reactor.
8. The method according to claim 1, wherein the pressure of the methane gas or the methane-containing gas in the reactor is 0.1 to 10 MPa.
9. The method according to claim 1, wherein the mass ratio of the catalyst to the chlorine salt is 0.01-0.5: 1.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103285894A (en) * | 2013-05-23 | 2013-09-11 | 河北科技大学 | Photocatalyst for halogenation reaction of organic matters and preparation method of photocatalyst |
| CN103301856A (en) * | 2013-05-23 | 2013-09-18 | 河北科技大学 | Application of nano noble metal/semiconductor composite photocatalyst to halogenation reaction of organic matters |
| CN106631678A (en) * | 2016-12-14 | 2017-05-10 | 厦门中科易工化学科技有限公司 | Chlorinating agent used for preparing chloromethane and application thereof and preparing method of chloromethane |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103285894A (en) * | 2013-05-23 | 2013-09-11 | 河北科技大学 | Photocatalyst for halogenation reaction of organic matters and preparation method of photocatalyst |
| CN103301856A (en) * | 2013-05-23 | 2013-09-18 | 河北科技大学 | Application of nano noble metal/semiconductor composite photocatalyst to halogenation reaction of organic matters |
| CN106631678A (en) * | 2016-12-14 | 2017-05-10 | 厦门中科易工化学科技有限公司 | Chlorinating agent used for preparing chloromethane and application thereof and preparing method of chloromethane |
Non-Patent Citations (1)
| Title |
|---|
| Direct conversion of methane to methanol, chloromethane and dichloromethane at room temperature;Kotaro Ogura et al.;《Nature》;19860123;第319卷;第308页 * |
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