TWI679060B - Catalyst applied for producing vinyl chloride by cracking 1,2-dichloroethane, method for producing the same, and method for regenerating the same - Google Patents

Abstract

The invention provides a catalyst, a preparation method and a regeneration method for 1,2-dichloroethane cracking to produce vinyl chloride. The catalyst is a supported nitrogen-containing carbon catalyst, and is a catalyst supporting a nitrogen-containing carbon material as a catalyst active component on the surface of an inorganic porous support. The preparation method is to support an inorganic porous carrier with an organic substance, and then perform thermal cracking in an atmosphere containing a nitrogen compound to perform a carbonization-nitridation process. The regeneration method is to calcine the catalyst after deactivation of carbon deposits in an oxidizing atmosphere, and after removing all carbonaceous portions on the surface, repeat the preparation process of the catalyst. Compared with the existing thermal cracking technology, the catalyst can reduce the reaction temperature, greatly reduce energy consumption, reduce production costs, and improve selectivity and conversion.

Description

Catalyst for cracking 1,2-dichloroethane to produce vinyl chloride Chemical agent, preparation method and regeneration method

The invention relates to a catalyst for cracking 1,2-dichloroethane to produce vinyl chloride, in particular to a supported nitrogen-containing carbon catalyst, a preparation method and a regeneration method.

Vinyl chloride is an important polymerized monomer used in polymer chemical industry. At present, the production process of vinyl chloride in the industry mainly includes ethylene method and calcium carbide acetylene method. In the production of polyvinyl chloride by the calcium carbide acetylene method, in addition to the large amount of calcium carbide slag and wastewater generated by the calcium chloride acetylene catalyst, which increases investment costs, it also causes pollution to the environment and poses a risk to human health. The aforementioned ethylene method for preparing vinyl chloride is currently recognized as an energy-saving and environmentally-friendly advanced production route in the world. There are three main processes in the ethylene process. The first step is to crack light diesel oil or chemical light oil in crude oil to obtain ethylene. The second step is to directly chlorinate or oxychlorinate ethylene to produce 1,2-dichloroethane. Alkane, the third step is 1,2-dichloroethane It is cracked in a high-temperature tubular cracking furnace to produce vinyl chloride. Therefore, the cracking of 1,2-dichloroethane is a crucial step in the ethylene process. The industrial reaction temperature is usually 500-600 ° C. At this time, the conversion of 1,2-dichloroethane is controlled at about 50%. Due to the high reaction temperature of high temperature thermal cracking, large energy consumption and easy coking, the pyrolysis furnace and subsequent separation process equipment are blocked by coking particles, which has a series of problems such as frequent coking and short production cycle. Nitrogen-containing carbon catalysts can catalyze the cracking of 1,2-dichloroethane, and can reduce the cracking temperature to 250-350 ° C, and improve the selectivity of vinyl chloride (Jinming Xu et al. "Synthesis of nitrogen-doped ordered mesoporous carbons for "Catalytic dehydrochlorination of 1,2-dichloroethane". Carbon, 2014, Volume 80, pp. 610-616; Wei Zhao et al. "Catalytic dehydrochlorination of 1,2-dichloroethane to produce vinyl chloride over N-doped coconut activated carbon ". RSC Advances. 2015, Vol. 5, pp. 104071-104078).

A Chinese invention patent with an application number of 201610256390.8 proposes a catalyst supporting activated carbon with a nitrogen-containing compound. This catalyst can reduce the current temperature for preparing vinyl chloride from industrial thermal cracking from 450-500 ° C to 280-300 ° C, and the one-way conversion rate of 1,2-dichloroethane can be increased from 50% to 93%, but its service life Shorter, inactivated in just 100 hours. This is due to the accumulation of coke and tar generated on the catalyst surface during the reaction process, which will cover the active center of the catalyst and block the catalyst pores with time, resulting in catalyst deactivation. This is all 1,2-dichloroethane cracking The preparation of vinyl chloride catalysts is an unavoidable process. Carbon-based catalysts, including nitrogen-doped activated carbon catalysts and activated carbon-supported barium chloride catalysts, cannot be removed by calcination in the air after deactivation of carbon deposits, which can not be accomplished by traditional hydrocarbon-like catalysts. Carbon deposits. If the air roasting method is adopted, the surface carbon can be easily removed. Even if the roasting conditions are carefully controlled, the structure of the carbon skeleton of the activated carbon catalyst itself will be damaged, and the strength of the carbon catalyst will decrease sharply, causing the catalyst to fail. Therefore, although the 1,2-dichloroethane catalytic cracking method can reduce the reaction temperature is an advantage, the high cost of the catalyst makes this production method less attractive than the traditional thermal cracking method.

Judging from the porous carbon catalysts reported so far, they all have the disadvantages of high cost, short life, and difficult regeneration, so they have not achieved industrial application. The supported nitrogen-containing carbon catalyst disclosed in the present invention uses nitrogen-containing carbon as the active component of the catalyst, and its content is relatively low, and an inorganic porous material is used as the support of the catalyst, so that the catalyst has high strength. The nitrogen-containing carbon is supported on the surface of the inorganic porous material. After being deactivated during use, the carbonaceous portion on the surface of the support can be removed by roasting, and the active component is reloaded to restore the catalyst activity. In the supported nitrogen-containing carbon catalyst of the present invention, the nitrogen-containing carbon is only used as an active component and its content is low, and the inorganic porous material can be recycled and reused, thereby greatly reducing the cost of the catalyst, making the catalyst extremely promising for industrial application. .

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a catalyst for catalyzing the cracking of 1,2-dichloroethane to produce vinyl chloride. Present invention A second object is to provide a method for preparing a catalyst for catalyzing the cracking and dehydrochlorination of 1,2-dichloroethane to produce vinyl chloride. A second object of the present invention is to provide a method for regenerating a catalyst for catalyzing the cracking and dehydrochlorination of 1,2-dichloroethane to produce vinyl chloride.

The technical solution of the present invention is summarized as follows.

The invention discloses a catalyst for the production of vinyl chloride by cracking 1,2-dichloroethane. The catalyst is a supported nitrogen-containing carbon catalyst. The nitrogen-containing carbon is used as the active component of the catalyst, and the inorganic porous material is used as the carrier of the catalyst. The nitrogen-containing carbon is supported on the surface of the inorganic porous material.

In the active component of the catalyst, the nitrogen element in the nitrogen-containing carbon is doped on the carbon material in the form of covalent bonds; the weight content of the nitrogen element in the nitrogen-containing carbon is 0.1-20% by weight. In some embodiments, the weight content of the nitrogen element in the nitrogen-containing carbon may also be 1-9% by weight.

In the catalyst, the weight content of nitrogen-containing carbon is 1-40% by weight, and the balance is an inorganic porous material carrier. In some embodiments, the weight content of the nitrogen-containing carbon may be 8-30% by weight, and the balance is an inorganic porous material carrier. The inorganic porous material contains at least one of silica, alumina, titania, and zirconia.

The invention also provides a preparation method of a catalyst for cracking 1,2-dichloroethane to produce vinyl chloride: first, an organic porous material is supported on an inorganic porous material, and then thermal cracking is performed in a nitrogen-containing compound atmosphere to carry out Carbonization-nitriding process. The weight average molecular weight of the organic precursor used may be less than 20,000.

The nitrogen-containing compound used is one or more of ammonia gas, hydrazine, acetonitrile, cyanamide, pyridine, pyrrole, ethylenediamine, methylamine or a derivative thereof, or a mixed gas with an inert gas. When a mixed gas of a nitrogen-containing compound and an inert gas is used, the content of the nitrogen-containing compound in the mixed gas is 0.5% by weight or more and less than 100% by weight.

The inert atmosphere used is a mixture of one or more of nitrogen, argon, or helium; the temperature of thermal cracking is 400-1000 ° C, and the time is 0.2-10 hours. In some embodiments, the temperature of thermal cracking may be 600-900 ° C, and the time is 0.5-6 hours.

The inert atmosphere used in the preparation method is a mixture of one or more of nitrogen, argon, or helium; the temperature of thermal cracking is 400-1000 ° C, and the time is 0.2-10 hours.

The invention also provides a method for regenerating a catalyst for the production of vinyl chloride from the cracking of 1,2-dichloroethane, which comprises calcining the supported carbon catalyst deactivated in the reaction in an oxidizing atmosphere to remove inorganic Carbon for porous materials. Then, the regenerated catalyst is prepared according to the above catalyst preparation method.

The oxidizing atmosphere used is oxygen, a mixed gas of oxygen and an inert gas, or air; the inert gas is one or two or more of mixed gases of nitrogen, argon, or helium. The content of oxygen in the oxidizing atmosphere may be 1-40% by weight. In some embodiments, the content of oxygen in the oxidizing atmosphere may be 3-22% by weight.

The roasting temperature used is 300-800 ° C; the roasting treatment time is 0.2-10 hours. In some embodiments, the firing temperature is 450-700 ° C, and the processing time is 0.5-6 hours.

The invention also provides an application of the nitrogen-doped oxide-supported carbon catalyst for catalyzing the cracking of 1,2-dichloroethane to produce vinyl chloride. Specifically, the 1,2-dichloroethane is vaporized and passed into a reactor equipped with the catalyst, wherein the volumetric space velocity (GHSV) of the reaction gas is 50-1000 h ^-1 and the cracking temperature is 200-300 ° C.

110‧‧‧ carrier

120‧‧‧ Nitrogen-containing carbon catalyst

130‧‧‧ carbon deposits

I‧‧‧ catalyst carrier

II‧‧‧ Catalyst

III‧‧‧Deactivated Catalyst

i‧‧‧ load stage

ii‧‧‧cracking reaction

iii‧‧‧ regeneration stage

In order to have a more complete understanding of the embodiments of the present invention and its advantages, please refer to the following description and cooperate with the corresponding drawings. It must be emphasized that the various features are not drawn to scale and are for illustration purposes only. The contents of the related drawings are described as follows: [Fig. 1] Schematic diagram of supported nitrogen-containing carbon catalyst, preparation, application and regeneration process.

The manufacture and use of the embodiments of the invention are discussed in detail below. It is understood, however, that the embodiments provide many applicable inventive concepts that can be embodied in a wide variety of specific content. The specific embodiments discussed are for illustration only and are not intended to limit the scope of the invention.

As shown in FIG. 1, the carrier 110 in the catalyst carrier (I) of the present case is firstly subjected to the supporting stage (i), and the organic precursor is supported on the surface of the carrier 110 and thermally cracked in a nitrogen-containing compound atmosphere to By performing the carbonization-nitriding process, a nitrogen-containing carbon catalyst 120 can be prepared, and the nitrogen-containing carbon catalyst 120 can be used in the cracking reaction (ii) of dichloroethane cracking to produce vinyl chloride. When this When the nitrogen-containing carbon catalyst 120 is deactivated due to carbon deposition 130, the carbonaceous portion on the surface can be removed by a regeneration stage (iii; that is, calcination in an oxidizing atmosphere), and the aforementioned loading stage (i) can be performed again. A nitrogen-containing carbon catalyst 120 having a catalytic effect is newly prepared.

The following uses examples to illustrate the application of the present invention, but it is not intended to limit the present invention. Any person skilled in the art can make various changes and decorations without departing from the spirit and scope of the present invention.

Example 1

At room temperature, add 0.4 g of oxalic acid in 40 mL of furan methanol with stirring, add 60 mL of xylene after dissolution, add 150 mL of silicone beads to the beaker and soak for 6 hours, filter to remove excess liquid, warm to 90 ° C, and then Polymerize for 12 hours.

Put the silica gel ball impregnated with furan methanol into a quartz tube. In a quartz tube furnace, the temperature was increased to 450 ° C. under a nitrogen atmosphere, and the temperature was kept constant for 3 hours. Then, it is switched to an ammonia gas atmosphere, heated to 600 ° C. at 5 ° C./min, and held constant for 3 hours to perform a carbonization-nitridation process to obtain a supported nitrogen-containing carbon catalyst.

For the application of a supported nitrogen-containing carbon catalyst, a 1,2-dichloroethane liquid that has been preheated and vaporized in an evaporator is passed through a constant-current pump and filled with 1,2-dichloroethane prepared in this embodiment for cracking. The catalyst is a fixed-bed reactor with a reactor temperature of 260 ° C and a space velocity of 180 h ^-1 . The conversion of dichloroethane in the reaction was 54%, and the selectivity of vinyl chloride was greater than 99%.

The deactivated catalyst was calcined in the air at 600 ° C for 1 hour, and the obtained silica gel was used as a carrier, and then used after being regenerated according to the catalyst preparation process, and its activity was not reduced.

Example 2

The preparation method is the same as that in Example 1 except that the ammonia gas treatment conditions in the carbonization-nitriding process are 800 ° C. and the temperature is constant for 1.5 hours.

The application process is the same as in Example 1, except that the reactor temperature is 260 ° C and the space velocity is 157h ^-1 . The conversion of dichloroethane in the reaction was 72%, and the selectivity of vinyl chloride was greater than 99%.

The deactivated catalyst was calcined in air at 450 ° C for 3 hours, and the obtained silicone was used as a carrier, and then used after being regenerated according to the catalyst preparation process, and its activity was not reduced.

Example 3

The preparation method was the same as that in Example 1 except that the amount of furan methanol was 25 mL, the amount of oxalic acid was 0.25 g, and the amount of toluene was 75 mL.

The application process is the same as in Example 1, except that the reactor temperature is 240 ° C. and the space velocity is 171 h ^-1 . The conversion of dichloroethane in the reaction was 36%, and the selectivity of vinyl chloride was greater than 99%.

The deactivated catalyst was calcined in air at 700 ° C. for 0.25 hours, and the obtained silica gel was used as a carrier, and then used after regeneration according to the above catalyst preparation process, and its activity was not reduced.

Example 4

50 g of alumina was placed in a 100 g aqueous solution containing 25 g of sucrose, and the water was evaporated to dryness at 100 ° C. The sucrose-impregnated alumina was heated to 800 ° C. in a tube furnace under the protection of argon containing 1% by weight of pyridine and kept constant for 3 hours to perform a carbonization-nitridation process to obtain a supported nitrogen-containing carbon catalyst.

The application process is the same as in Example 1, except that the reactor temperature is 260 ° C and the space velocity is 133 h ^-1 . The conversion of dichloroethane in the reaction was 54%, and the selectivity of vinyl chloride was greater than 99%.

The deactivated catalyst was calcined in a mixed atmosphere of 15% by weight O ₂ and 85% by weight N ₂ at 600 ° C. for 2 hours. The obtained alumina was used as a carrier and then regenerated according to the catalyst preparation process described above. reduce.

Example 5

50 g of zirconia was placed in 100 g of an absolute ethanol solution containing 15 g of a phenol resin (weight average molecular weight: 1000), and the absolute ethanol was evaporated to dryness at 80 ° C. The phenolic resin impregnated zirconia was heated to 750 ° C. in a tube furnace under the protection of nitrogen containing 5% by weight of acetonitrile, and was held at a constant temperature for 3 hours to perform a carbonization-nitridation process to obtain a supported nitrogen-containing carbon catalyst.

The application process is the same as in Example 1, except that the reactor temperature is 250 ° C. and the space velocity is 133 h ^-1 . The conversion of dichloroethane in the reaction was 36%, and the selectivity of vinyl chloride was greater than 99%.

The deactivated catalyst was calcined in the air at 600 ° C for 2 hours, and the obtained alumina was used as a carrier, and then used after regeneration according to the catalyst preparation process described above, and its activity was not reduced.

Although the present invention has been disclosed as above in the embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Retouching, so the scope of protection of the present invention shall be determined by the scope of the attached patent application.

Claims (16)

A catalyst for the production of vinyl chloride from the cracking of 1,2-dichloroethane, characterized in that the catalyst is a supported nitrogen-containing carbon catalyst, a nitrogen-containing carbon is an active component of the catalyst, and an inorganic porous material As a support for the catalyst, the nitrogen-containing carbon is supported on a surface of the inorganic porous material, wherein the inorganic porous material is not activated carbon; the nitrogen element in the nitrogen-containing carbon is doped in the carbon material in the form of covalent bonds. The content of the nitrogen element in the nitrogen-containing carbon is 0.1% to 20% by weight. In the catalyst, the content of the nitrogen-containing carbon is 1% to 40% by weight, and the balance is the inorganic porous material. . The catalyst for cracking 1,2-dichloroethane to produce vinyl chloride as described in item 1 of the scope of the patent application, wherein the content of the nitrogen element in the nitrogen-containing carbon is 1% to 9% by weight. The catalyst for cracking 1,2-dichloroethane to produce vinyl chloride as described in item 1 of the scope of the patent application, in the catalyst, the content of the nitrogen-containing carbon is 8% to 30% by weight, and the balance is This is an inorganic porous material. The catalyst for cracking 1,2-dichloroethane to produce vinyl chloride as described in item 1 of the scope of the patent application, wherein the inorganic porous material comprises at least one of silica, alumina, titania and zirconia. A method for preparing a catalyst for cracking 1,2-dichloroethane to produce vinyl chloride as described in any one of items 1 to 4 of the scope of patent application, comprising: firstly loading an inorganic porous material with an organic The precursor is then thermally cracked in a nitrogen-containing compound atmosphere to perform a carbonization-nitriding process, and a nitrogen-containing carbon is supported on a surface of the inorganic porous material, wherein the inorganic porous material is not activated carbon; The temperature of the thermal cracking is 400 ° C to 1000 ° C, and the time is 0.2 hours to 10 hours. In the catalyst, the content of the nitrogen-containing carbon is 1% to 40% by weight, and the balance is the inorganic porous material. Wherein, the nitrogen-containing carbon contains 0.1% to 20% by weight of nitrogen element. The preparation method according to item 5 of the patent application range, wherein the temperature of the thermal cracking is 600 ° C to 900 ° C, and the time is 0.5 hours to 6 hours. The preparation method according to item 5 of the scope of patent application, wherein the nitrogen-containing compound atmosphere includes a nitrogen-containing compound, or a mixed gas of a nitrogen-containing compound and an inert gas; the nitrogen-containing compound is ammonia, hydrazine, Acetonitrile, cyanamide, pyridine, pyrrole, ethylenediamine and / or methylamine. The preparation method as described in item 5 of the scope of patent application, wherein the weight average molecular weight of the organic precursor is less than 20,000, and it is soluble in water or an organic solvent. The preparation method according to item 8 of the scope of patent application, wherein the organic solvent is a hydrocarbon solvent having 1 to 18 carbon atoms, a halogenated hydrocarbon solvent, an alcohol solvent, an ether solvent, an ester solvent, and a ketone. Solvents, amine solvents, acid solvents, phenol solvents, nitrile solvents, furan solvents, pyridine and / or pyrrole solvents; the organic precursors are acrylonitrile, vinyl chloride, dichloroethylene, vinylpyridine, propylene Amine, acrylic compound, vinyl ester compound, aniline compound, pyrrole compound, urea resin, phenol resin, melamine resin, polyurethane, furan resin, glucose, fructose, xylose, sucrose, dextran, lignin, organic matter pyrolysis Oil and / or asphalt. The preparation method according to claim 5, 8, or 9, wherein one of the supporting methods for supporting the organic precursor on the inorganic porous material is impregnating the organic precursor with a liquid or impregnating one containing the organic precursor. A solution; or spraying the organic precursor of a liquid or spraying a solution containing the organic precursor. The preparation method according to item 7 of the scope of patent application, wherein the inert gas is nitrogen, argon, and / or helium; when the mixed gas of the nitrogen-containing compound and the inert gas is used, the nitrogen-containing compound is in the The content in the mixed gas is 0.5% by weight or more and less than 100% by weight. A method for regenerating a catalyst for cracking 1,2-dichloroethane to produce vinyl chloride as described in any one of claims 1 to 4 of the scope of patent application, comprising: the catalyst is catalyzing the 1,2- After deactivation of a reaction for producing the vinyl chloride by cracking dichloroethane, the deactivated catalyst is calcined in an oxidizing atmosphere to remove the carbon of the inorganic porous material; and the calcined inorganic porous material is used as a carrier, and The catalyst is prepared and regenerated according to the preparation method described in any one of items 5 to 11 of the scope of patent application. The regeneration method according to item 12 of the scope of the patent application, wherein the oxidizing atmosphere is a mixed gas or air of oxygen and an inert gas; the inert gas is nitrogen, argon, and / or helium; when the oxidizing atmosphere is When the mixed gas is the oxygen and the inert gas, the content of the oxygen in the oxidizing atmosphere is 1% to 40% by weight. According to the regeneration method described in item 13 of the scope of patent application, when the oxidizing atmosphere is the mixed gas of the oxygen and the inert gas, the content of the oxygen in the oxidizing atmosphere is 3% to 22% by weight. The regeneration method according to item 12 of the scope of the patent application, wherein the baking temperature is 300 ° C to 800 ° C, and the processing time is 0.2 hours to 10 hours. The regeneration method according to item 12 of the scope of patent application, wherein the baking temperature is 450 ° C to 700 ° C, and the processing time is 0.5 hours to 6 hours.