A continuous process for the preparation of decanediol and catalysts used therein

Abstract

The application discloses a catalyst for preparing sebacic dinitrile and a preparation method and application thereof, and belongs to the field of catalysis. The application of the catalyst in preparation of sebacic dinitrile is as follows: sebacic acid and urea are mixed according to a certain proportion, are sent into a continuous reactor by a solid feeder at a certain rate, react with the catalyst in the reaction tube, are removed from the reactor in a gaseous form along with fluidizing gas, and are liquefied in a receiver; the liquid-solid mixed product is subjected to extraction, liquid separation, and then is subjected to solvent removal under normal pressure and vacuum rectification to obtain a high-purity product, the conversion rate of sebacic acid is greater than 99%, and the selectivity of sebacic dinitrile is greater than 99%. The application has the characteristics of low cost, easy preparation, moderate reaction condition, avoidance of use of toxic solvents, convenience of post-treatment, high product purity and the like.

Description

Technical Field

[0001] This invention belongs to the field of catalytic synthesis and relates to a method for preparing sebacite from sebaic acid through a continuous selective dehydration reaction, as well as the catalyst used in this method. Background Technology

[0002]

[0003] Sebaconitrile, CAS No. 1871-96-1, is a colorless or pale yellow liquid with a melting point of 7–8°C and a boiling point of 204°C (2.13 kPa). It is soluble in acetone and ether, but insoluble in water. It is an important chemical intermediate with wide applications in pharmaceutical synthesis and the preparation of novel fiber plastics. It can also be used as a solvent, plasticizer, and lithium-ion battery additive, and has a promising market prospect.

[0004]

[0005] Currently, the main processes for generating sebaonitrile are as follows: (1) Sebaonitrile is prepared by condensation of acetonitrile with 1,6-dibromohexane, but the yield is low (50% to 70%) and the raw materials are expensive; (2) Sebaonitrile is prepared by nucleophilic substitution of 1,8-dibromooctane with potassium cyanide or sodium cyanide in DMF solvent, but the latter two are highly toxic controlled products, posing a great risk to production safety; (3) Sebaonitrile is prepared by adding trifluoroacetic anhydride as a dehydrating agent to sebaamide, but trifluoroacetic anhydride is volatile, easily hydrolyzed, and irritating, which is not conducive to industrial production; (4) Sebaonitrile is often prepared by ammonolysis of sebaic acid (as shown in the figure above) with a nitrogen source at high temperature (>300℃). It is generally a one-pot batch reaction. The raw materials are cheap, but the long-term high-temperature reaction leads to easy carbonization of organic matter and a lot of by-products. Therefore, for the synthesis of sebacate, simplifying reaction steps and process flow, reducing the use of organic solvents, and achieving continuous production with minimal waste emissions are urgent needs in industrial production.

[0006] CN 107266335 A proposes a method of heating and melting sebacic acid, followed by batch addition of urea for a condensation reaction. This method offers relatively mild reaction conditions, convenient post-processing, and simple equipment requirements. However, it uses thionyl chloride and / or phosphorus oxychloride as dehydrating agents, both of which are toxic, irritating, or corrosive. Furthermore, the subsequent separation process uses controlled substances as high-boiling-point solvents, posing significant risks to equipment safety and the health of production personnel. The intermittent reaction method also leads to water in the system affecting the reaction rate and causing severe catalyst carbon buildup. For improving the production efficiency of sebacic acid, the cost, catalytic efficiency, and safety of the catalyst are crucial. Biochar materials possess abundant surface pore structures and easily tunable surface groups, giving them catalytic activity and product selectivity different from traditional metal oxides. By doping carbon materials with heterogeneous elements, the surface properties of the material can be controlled. Therefore, by rationally designing and controlling the catalyst according to the active sites required for different reactions, highly efficient catalysts with high selectivity for specific reactions can be synthesized. This catalyst has advantages such as wide availability of raw materials, renewability, easy control of catalyst surface properties, and no use of metal components, and is gradually attracting attention. Its application in the dehydration of sebacic acid to sebaconitrile is of great significance. Summary of the Invention

[0007] Technical issues

[0008] One object of this application is to provide a method for preparing sebacite from sebaic acid via a continuous selective dehydration reaction, and a catalyst used in this method. The catalyst prepared according to this application exhibits excellent catalytic performance and selectivity for sebacite, achieving a conversion rate of >99% for sebaic acid and a selectivity of >99% for sebacite. While ensuring the yield of the target product, high-purity sebacite can be obtained using simple distillation, significantly reducing the cost of subsequent separation.

[0009] Another objective of this application is to provide a method for preparing the aforementioned catalyst.

[0010] Another object of this application is to provide the use of the above-mentioned catalyst in a method for preparing sebacate.

[0011] Technical solution

[0012] According to one embodiment of this application, the present invention provides a method for preparing sebacite from sebaic acid through a continuous selective dehydration reaction, wherein the method involves a continuous selective dehydration reaction of sebaic acid and a nitrogen source in a reactor in the presence of a catalyst.

[0013] Preferably, the reactor is selected from any one of batch reactors, semi-batch reactors, continuous stirred tank reactors, plug flow reactors, fixed phase reactors, and fluidized bed reactors, or it can be a mixed reactor consisting of two or more of these reactors connected together; preferably, it is a fluidized bed reactor.

[0014] Preferably, the nitrogen source is selected from urea, ammonia, ammonia water, and ammonium carbonate;

[0015] More preferably, the nitrogen source is urea.

[0016] Preferably, the method according to the present invention is carried out as follows: a certain proportion of sebacic acid and a nitrogen source are mixed, and then fed in the form of solid powder along with fluidizing gas, or sebacic acid is fed in the form of solid powder along with fluidizing gas, and a liquid or gaseous nitrogen source is introduced into the reactor in a certain proportion along with fluidizing gas through a separate pipeline. Under a certain pressure, the two react in the reactor in the form of gas and then leave the reactor with fluidizing gas to obtain a mixture of sebaconitrile and inorganic salt. Subsequently, high-purity sebaconitrile product is obtained by extraction, separation, and vacuum distillation.

[0017] Preferably, the molar ratio of sebacic acid to nitrogen source is 1:(2-8), such as 1:2, 1:4, 1:5, 1:6, 1:7 or 1:8.

[0018] Preferably, the reaction temperature is 250-400℃, such as 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃ or 360℃, and more preferably 300-330℃.

[0019] Preferably, the fluidizing gas rate in the reaction process is 1 to 5 L / min, such as 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, etc., and more preferably 2 to 3 L / min.

[0020] Preferably, the space velocity of the reaction process is 0.05 h⁻¹. -1 ~5h -1 Preferably 0.1h -1 ~3h -1 .

[0021] Preferably, the fluidizing gas is one or more of nitrogen atmosphere, helium atmosphere, and argon atmosphere.

[0022] Preferably, the catalyst is in the form of strips, columns, or flakes.

[0023] Preferably, the method for preparing sebacate is carried out at a reaction pressure of atmospheric pressure to 4 MPa, and more preferably atmospheric pressure to 2 MPa.

[0024] On the other hand, the present invention provides a catalyst for preparing sebacate, said catalyst being prepared by a method comprising the following steps:

[0025] 1. After the dried biomass raw material is crushed by a pulverizer, it is added together with the solid acid catalyst and ball-milled into a fine powder of 200-400 mesh. The powder is then added to a reaction vessel, distilled water is added, the reaction vessel is sealed, and the mixture is heated to 150-250℃ for hydrolysis reaction for 4-10 hours. After the reaction is completed, the temperature is lowered, the pressure is released, and the mixture is filtered under reduced pressure. The filtrate is then distilled and concentrated to 20% of its original volume to obtain a concentrated solution.

[0026] 2. Add the acid solution to the concentrated solution described in step 1 under vigorous stirring. After mixing evenly, add chitosan and transfer to a hydrothermal reactor. Perform hydrothermal treatment at 160-220℃ for 4-20 hours. After cooling and depressurization, wash the obtained product three times with anhydrous ethanol and deionized water respectively, and then dry it at 110℃ for 12 hours to obtain the doped carbon material.

[0027] 3. Add alkali to the doped carbon material obtained in step 2, stir and mix evenly, place it in a tube furnace, heat to 300-700℃ under an inert gas atmosphere for carbonization treatment for 4-20 hours. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12 hours.

[0028] 4. Mix the doped carbon material obtained in step 3 with acid or oxidant and stir evenly. Heat to 60-90℃ for 4-10 hours. After treatment, cool down and filter. Wash the material with distilled water until the filtrate is neutral. Dry at 110℃ for 12 hours.

[0029] Preferably, the filter cake obtained after filtration in step 1 contains the solid acid catalyst. The filter cake is calcined at 350-550°C for 3-6 hours to remove organic matter, thereby obtaining the solid acid catalyst. The obtained solid acid catalyst can be recycled.

[0030] In step 1 above, the biomass material includes one or more of the following: corn cobs, corn stalks, sawdust, peanut shells, and bamboo shoots.

[0031] Preferably, the biomass material in step 1 includes one or more of corn cobs, corn stalks, and peanut shells.

[0032] More preferably, the biomass material in step 1 includes one or more of corn cobs and corn stalks.

[0033] In step 1 above, the solid acid catalyst includes one or more of the following: silicon dioxide, γ-alumina, zirconium dioxide, cerium dioxide, tungsten trioxide, niobium pentoxide, zeolite molecular sieve, and ion exchange resin.

[0034] Preferably, the solid acid catalyst comprises one or more of the following: silicon dioxide, γ-alumina, tungsten trioxide, niobium pentoxide, zeolite molecular sieve, and ion exchange resin.

[0035] More preferably, the solid acid catalyst includes one or more of γ-alumina, zeolite molecular sieves, and ion exchange resins.

[0036] Preferably, the zeolite molecular sieve includes one or more of HZSM5, HZSM11, HY, Hβ, HMOR, and SAPO-34.

[0037] In step 1 above, the mass ratio of distilled water to biomass raw material is 50:1-2:1.

[0038] Preferably, in step 1 above, the mass ratio of distilled water to biomass raw material is 20:1-5:1.

[0039] In step 1 above, the hydrolysis reaction temperature is 120-250℃.

[0040] Preferably, in step 1 above, the hydrolysis reaction temperature is 150-220℃.

[0041] More preferably, in step 1 above, the hydrolysis reaction temperature is 160-210℃.

[0042] In step 1 above, the hydrolysis reaction time is 4-10 hours.

[0043] Preferably, in step 1 above, the hydrolysis reaction time is 4-6 hours.

[0044] In step 1 above, the mass concentration of the concentrated solution is 10%-30%.

[0045] Preferably, in step 1 above, the mass concentration of the concentrated solution is 10%-20%.

[0046] In step 2 above, the acid is selected from one or more of formic acid, acetic acid, propionic acid, and hydrochloric acid.

[0047] In step 2 above, the mass concentration of the acid solution is 1%-30%.

[0048] Preferably, in step 2 above, the mass concentration of the acid solution is 3%-10%.

[0049] In step 2 above, the mass ratio of the acid solution to the concentrated solution is 1:1 to 10:1.

[0050] Preferably, in step 2 above, the mass ratio of the acid solution to the concentrated solution is 1:1 to 5:1.

[0051] In step 2 above, the mass ratio of chitosan to concentrated solution is 1:10 to 1:100.

[0052] In step 2 above, the hydrothermal treatment temperature is 160-220℃.

[0053] Preferably, in step 2 above, the hydrothermal treatment temperature is 180-210℃.

[0054] In step 2 above, the hydrothermal treatment time is 4-20 hours.

[0055] Preferably, in step 2 above, the hydrothermal treatment time is 5-10 hours.

[0056] In step 3 above, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, and potassium ethoxide.

[0057] In step 3 above, the mass ratio of the alkali to the doped carbon material is 1:1 to 10:1.

[0058] Preferably, in step 3 above, the mass ratio of the alkali to the doped carbon material is 1:1 to 5:1.

[0059] More preferably, in step 3 above, the mass ratio of the alkali to the doped carbon material is 1:1 to 3:1.

[0060] In step 3 above, the inert gas used in the carbonization process includes one or more of nitrogen, helium, and argon.

[0061] Preferably, in step 3 above, the inert gas used in the carbonization process includes one or more of nitrogen and argon.

[0062] In step 4 above, the acid is one or more of sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, and phosphoric acid. The oxidant is one or more of hydrogen peroxide (30 wt%) and sodium hypochlorite (6% available chlorine).

[0063] In step 4 above, the mass ratio of the acid to the carbon material is 1:1 to 10:1.

[0064] In step 4 above, the mass ratio of the acid to the carbon material is 1:1 to 10:1.

[0065] In step 4 above, the mass ratio of the oxidant to the carbon material is 1:1 to 10:1.

[0066] In step 4 above, the processing temperature is 60-90℃.

[0067] In step 4 above, the processing time is 4-10 hours.

[0068] On the other hand, the present invention provides the use of the catalyst in a method for preparing sebacate.

[0069] Beneficial effects

[0070] (1) The preparation method of the present invention uses sebacic acid urea as raw material to prepare sebaconitrile, which has excellent catalytic efficiency (>99%) and very high selectivity for the target product sebaconitrile (>99%). The targeted addition of acidic sites significantly improves the catalytic performance of the catalyst and enhances the selectivity of the target product sebaconitrile.

[0071] (2) The preparation method of the present invention has less pollution than the traditional method, and the continuous reaction in the fluidized bed allows the product to leave the reactor in time, reducing carbon buildup and coking, and the catalyst can maintain high stability and service life.

[0072] (3) The catalyst described in this invention is suitable for catalyzing the reaction of preparing sebacite from a mixture of sebacite and urea in a fluidized bed reactor, which solves the problems of dependence on organic solvents and low product yield in the traditional fixed bed reactor catalysis process. Attached Figure Description

[0073] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0074] Figure 1 A schematic diagram of a fluidized bed reactor for a method of continuous preparation of sebacate according to an embodiment of the present invention;

[0075] Figure 2 To prepare Example 6, the ammonia temperature-programmed desorption test results of the catalyst products of Comparative Example 1 and Comparative Example 2 were compared. Detailed Implementation

[0076] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before description, it should be understood that the terminology used in the specification and appended claims should not be construed as limited to its general and dictionary meaning, but rather should be interpreted based on the principle of allowing the inventors to appropriately define the terminology for the best interpretation, and based on its meaning and concept corresponding to the technical level of the invention. Therefore, the description herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention; thus, it should be understood that other equivalent implementations and modifications can be made without departing from the spirit and scope of the invention.

[0077] In this document, the terms “comprising,” “including,” “having,” “containing,” or any other similar terms are open-ended conjunctions intended to cover non-exclusive inclusions. For example, a composition or article containing a plurality of elements is not limited to those listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated to the contrary, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as “composed of” and “substantially composed of.”

[0078] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0079] If a quantity or other numerical value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0080] In this document, numerical values ​​are to be understood as having a precision with significant digits, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover a range from 39.50 to 40.49.

[0081] To clarify the invention, parts irrelevant to the description have been omitted from the drawings, and throughout the specification, the same or similar parts are indicated by the same reference numerals.

[0082] Furthermore, for ease of explanation, the dimensions and thicknesses of each component shown in the accompanying drawings are arbitrarily illustrated; therefore, the invention is not necessarily limited to those shown in the drawings.

[0083] Throughout the specification, when it is said that an element is "connected" to another element, it includes not only "direct connection" but also "indirect connection" between other components. Furthermore, when it is said that an element "comprises" a part, it means that the element may further include other parts rather than exclude them, unless otherwise explicitly stated.

[0084] Preferably, the reactor in the method according to the present invention is selected from any one of the following reactors: batch reactor, semi-batch reactor, continuous stirred tank reactor, plug flow reactor, stationary phase reactor, and fluidized bed reactor; or it can be a mixed reactor consisting of two or more of these reactors connected together; preferably, it is a fluidized bed reactor. For example, the reactor tube dimensions are: upper section inner diameter 100 mm, outer diameter 108 mm, length 300 mm; lower section inner diameter 40 mm, outer diameter 48 mm, length 200 mm, filled with 300 g of catalyst. However, the reactor of the present invention is not limited to the above specific dimensions, and the dimensions of the reactor and the amount of catalyst loaded can be adjusted according to actual needs.

[0085] The catalyst-related content of this invention will be protected by a separate patent application.

[0086] The following embodiments are merely examples of implementation schemes of the present invention and do not constitute any limitation on the present invention. Those skilled in the art will understand that any modifications that do not depart from the spirit and concept of the present invention fall within the protection scope of the present invention.

[0087] Unless otherwise specified, all raw materials used in this invention are commercially available, and all methods and equipment used are conventional methods and equipment in the field.

[0088] In the following examples, sebacic acid, urea, sodium hydroxide, and potassium hydroxide were purchased from Sinopharm Chemical Reagent Co., Ltd.; high-purity nitrogen and high-purity helium were purchased from Qingdao Dehai Weiye Technology Co., Ltd.; and corn cobs, corn stalks, and peanut shells were purchased locally.

[0089] In the method for preparing sebacite according to the present invention, sebaic acid and a nitrogen source (e.g., urea) are used as raw materials, and sebacite is obtained through an amination and dehydration reaction. The separated product is filtered through a 0.22 μm filter membrane and analyzed by gas chromatography (GC). Qualitative analysis of the low-boiling-point product is performed by GC-MS and comparison with the GC retention time of a standard, confirming that the main reaction product is sebacite. Quantitative determination of the low-boiling-point substance is performed using a Shimadzu-GC 2020 gas chromatograph, and quantitative analysis is performed by comparing the retention time with that of a standard and the peak area. The relevant calculation formulas are as follows:

[0090] Conversion rate of sebacic acid

[0091] Selectivity of sebacate

[0092] Single-pass yield of sebacate

[0093]

[0094]

[0095] The flow rate of the raw material is expressed in g / min, and the amount of catalyst is expressed in g.

[0096] Figure 1 This is a schematic diagram of a fluidized bed reactor for a method of continuous preparation of sebacate according to one embodiment of the present invention. (Reference) Figure 1 The reaction tube is filled with the catalyst according to this application. First, a fluidizing gas is introduced into the reaction tube at a controlled flow rate using a mass flow meter to create a fluidized state for the catalyst. Then, a heater can be used to heat and activate the catalyst. Next, while maintaining the temperature of the reaction tube, the raw material is fed into the reaction tube via a feed pump (liquid), a solid feeder (solid), or a mass flow meter (gas). Under the influence of a fluidizing gas atmosphere and catalyst catalysis, the reaction produces a product containing sebacate. After condensation and gas-liquid separation, the sebacate product can be collected.

[0097] Example

[0098] Preparation Example 1

[0099] 1. After crushing 150g of dried corn cob in a pulverizer, add it together with 15g of HZSM5 catalyst to a ball mill and ball mill it into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 800ml of distilled water, seal the reaction vessel, heat to 200℃, and carry out the hydrolysis reaction for 6 hours. After the reaction is completed, cool down, depressurize, filter under reduced pressure, and distill and concentrate the filtrate to obtain 143ml of concentrated solution.

[0100] 2. Add 200 ml of a 10% formic acid solution to the concentrated solution described in step 1 under vigorous stirring. Add 5 g of chitosan, mix well, and then add the mixture to a hydrothermal reactor. Hydrothermally treat the mixture at 180°C for 10 h. After cooling and depressurization, wash the resulting product three times with anhydrous ethanol and deionized water, respectively, and then dry it at 110°C for 12 h to obtain the doped carbon material.

[0101] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of potassium hydroxide, stir and mix evenly, place in a tube furnace, heat to 500℃ under an inert gas atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h.

[0102] 4. Add 100 ml of 20 wt% nitric acid aqueous solution to 10 g of the doped carbon material obtained in step 3, heat to 60 °C for 6 h, cool and filter, wash the material with distilled water until the filtrate is neutral, and dry at 110 °C for 12 h. After cooling, take it out to obtain catalyst 1.

[0103] Preparation Example 2

[0104] 1. After pulverizing 150g of dried bamboo shoots with a pulverizer, add them together with 15g of HY catalyst to a ball mill and grind them into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 800ml of distilled water, seal the reaction vessel, and heat to 200℃ for hydrolysis reaction for 6h. After the reaction is completed, cool down, depressurize, filter under reduced pressure, and distill and concentrate the filtrate to obtain 140ml of concentrated solution.

[0105] 2. Add 200 ml of 10% acetic acid solution to the concentrated solution described in step 1 under vigorous stirring, then add 5 g of chitosan and mix well. Add the mixture to a hydrothermal reactor and hydrothermally treat at 180°C for 10 h. After cooling and depressurization, wash the obtained product three times with anhydrous ethanol and deionized water respectively, and then dry at 110°C for 12 h to obtain the doped carbon material.

[0106] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of potassium hydroxide, stir and mix evenly, place in a tube furnace, heat to 600℃ under an inert gas atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h.

[0107] 4. Add 100 ml of 30 wt% hydrochloric acid to 10 g of the doped carbon material obtained in step 3, heat to 70 °C for 6 h, cool and filter, wash the material with distilled water until the filtrate is neutral, and dry at 110 °C for 12 h. After cooling, take it out to obtain catalyst 2.

[0108] Preparation Example 3

[0109] 1. After crushing 300g of dried peanut shells with a pulverizer, add them together with 30g of Hβ catalyst to a ball mill and ball mill them into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 1500ml of distilled water, seal the reaction vessel, heat to 200℃, and carry out the hydrolysis reaction for 6 hours. After the reaction is completed, cool down, depressurize, filter under reduced pressure, and distill and concentrate the filtrate to obtain 380ml of concentrated solution.

[0110] 2. Add 400 ml of 10% hydrochloric acid solution to the concentrated solution described in step 1 under vigorous stirring, add 10 g of chitosan, mix well, and then add to a hydrothermal reactor. Treat the mixture at 180°C for 10 h. After cooling and depressurization, wash the resulting product three times with anhydrous ethanol and deionized water, and then dry it at 110°C for 12 h to obtain the doped carbon material.

[0111] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of potassium hydroxide, stir and mix evenly, place in a tube furnace, heat to 600℃ under an inert gas atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h.

[0112] 4. Add 100 ml of sodium hypochlorite aqueous solution (6% available chlorine) to 15 g of the doped carbon material obtained in step 3, heat to 60 °C for 6 h, cool and filter, wash the material with distilled water until the filtrate is neutral, and dry at 110 °C for 12 h. After cooling, take it out to obtain catalyst 3.

[0113] Preparation Example 4

[0114] 1. After crushing 300g of dried peanut shells with a pulverizer, add them together with 30g of Hβ catalyst to a ball mill and ball mill them into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 1500ml of distilled water, seal the reaction vessel, heat to 200℃, and carry out the hydrolysis reaction for 6 hours. After the reaction is completed, cool down, release the pressure, filter under reduced pressure, and distill and concentrate the filtrate to obtain 369ml of concentrated solution.

[0115] 2. Add 400 ml of a 10% formic acid solution to the concentrated solution described in step 1 under vigorous stirring. Add 6 g of chitosan and mix well. Then, add the mixture to a hydrothermal reactor and hydrothermally treat it at 180°C for 10 h. After cooling and depressurization, wash the resulting product three times with anhydrous ethanol and deionized water, respectively. Then, dry it at 110°C for 12 h to obtain the doped carbon material.

[0116] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of potassium hydroxide, stir and mix evenly, place in a tube furnace, heat to 600℃ under an inert gas atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h.

[0117] 4. Add 100 ml of 20 wt% sulfuric acid aqueous solution to 18 g of the doped carbon material obtained in step 3, heat to 80 °C for 6 h, cool and filter, wash the material with distilled water until the filtrate is neutral, and dry at 110 °C for 12 h. After cooling, take it out to obtain catalyst 4.

[0118] Preparation Example 5

[0119] 1. After crushing 300g of dried corn stalks in a pulverizer, add them together with 30g of γ-Al2O3 catalyst to a ball mill and grind them into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 1500ml of distilled water, seal the reaction vessel, and heat to 200℃ for hydrolysis reaction for 6h. After the reaction is completed, cool down, depressurize, filter under reduced pressure, and distill and concentrate the filtrate to obtain 369ml of concentrated solution.

[0120] 2. Add 400 ml of 10% acetic acid solution to the concentrated solution described in step 1 under vigorous stirring. Add 4 g of chitosan and mix well. Then, add the mixture to a hydrothermal reactor and hydrothermally treat it at 180°C for 10 h. After cooling and depressurization, wash the obtained product three times with anhydrous ethanol and deionized water, respectively. Then, dry it at 110°C for 12 h to obtain the doped carbon material.

[0121] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of potassium hydroxide, stir and mix evenly, place in a tube furnace, heat to 600℃ under nitrogen atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h.

[0122] 4. Add 100 ml of 20 wt% nitric acid aqueous solution to 15 g of the doped carbon material obtained in step 3, heat to 60 °C for 6 h, cool and filter, wash the material with distilled water until the filtrate is neutral, and dry at 110 °C for 12 h. After cooling, take out to obtain catalyst 5.

[0123] Preparation Example 6

[0124] 1. Crush 300g of dried corn cobs using a pulverizer, and then add them together with 30g of Nb2O5 to a ball mill to grind them into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 1500ml of distilled water, seal the reaction vessel, and heat to 200℃ for hydrolysis reaction for 6 hours. After the reaction is completed, cool down, release the pressure, filter under reduced pressure, and distill and concentrate the filtrate to obtain 341ml of concentrated solution.

[0125] 2. Add 400 ml of 10% acetic acid solution to the concentrated solution described in step 1 under vigorous stirring, add 5 g of chitosan, mix well, and then add to a hydrothermal reactor. Hydrothermally treat at 180°C for 10 h. After cooling and depressurization, wash the obtained product three times with anhydrous ethanol and deionized water respectively, and then dry at 110°C for 12 h to obtain the doped carbon material.

[0126] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of sodium hydroxide, stir and mix evenly, place in a tube furnace, heat to 600℃ under nitrogen atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h.

[0127] 4. Add 100 ml of 40 wt% sulfuric acid aqueous solution to 15 g of the doped carbon material obtained in step 3, heat to 60 °C for 6 h, cool and filter, wash the material with distilled water until the filtrate is neutral, and dry at 110 °C for 12 h. After cooling, take it out to obtain catalyst 6.

[0128] Comparative Example 1

[0129] 1. Crush 300g of dried corn cobs using a pulverizer, and then add them together with 30g of Nb2O5 to a ball mill to grind them into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 1500ml of distilled water, seal the reaction vessel, and heat to 200℃ for hydrolysis reaction for 6 hours. After the reaction is completed, cool down, release the pressure, filter under reduced pressure, and distill and concentrate the filtrate to obtain 341ml of concentrated solution.

[0130] 2. Add 400 ml of acetic acid solution with a mass percentage concentration of 10% to the concentrated solution in step 1 under vigorous stirring. After mixing evenly, add the solution to a hydrothermal reactor and hydrothermally treat it at 180°C for 10 h. After cooling and depressurization, wash the obtained product three times with anhydrous ethanol and deionized water respectively, and then dry it at 110°C for 12 h to obtain the doped carbon material.

[0131] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of sodium hydroxide, stir and mix evenly, place in a tube furnace, heat to 600℃ under nitrogen atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h.

[0132] 4. Add 100 ml of 40 wt% sulfuric acid aqueous solution to 15 g of the doped carbon material obtained in step 3, heat to 60 °C for 6 h, cool and filter, wash the material with distilled water until the filtrate is neutral, and dry at 110 °C for 12 h. After cooling, take it out to obtain comparative catalyst 1.

[0133] Comparative Example 2

[0134] 1. Crush 300g of dried corn cobs using a pulverizer, and then add them together with 30g of Nb2O5 to a ball mill to grind them into a fine powder of 200-400 mesh. Add the powder to a reaction vessel, add 1500ml of distilled water, seal the reaction vessel, and heat to 200℃ for hydrolysis reaction for 6 hours. After the reaction is completed, cool down, release the pressure, filter under reduced pressure, and distill and concentrate the filtrate to obtain 341ml of concentrated solution.

[0135] 2. Add 400 ml of acetic acid solution with a mass percentage concentration of 10% to the concentrated solution in step 1 under vigorous stirring. After mixing evenly, add the solution to a hydrothermal reactor and hydrothermally treat it at 180°C for 10 h. After cooling and depressurization, wash the obtained product three times with anhydrous ethanol and deionized water respectively, and then dry it at 110°C for 12 h to obtain the doped carbon material.

[0136] 3. Take 20g of the doped carbon material obtained in step 2, add 60g of sodium hydroxide, stir and mix evenly, place in a tube furnace, heat to 600℃ under nitrogen atmosphere for carbonization treatment for 5h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h to obtain comparative catalyst 2.

[0137] Characterization of catalyst products

[0138] 1. Catalyst elemental analysis

[0139] Table 1 below shows the elemental analysis results of the catalyst products prepared in Examples 1-6 and Comparative Examples 1-2.

[0140] Table 1: Elemental Analysis of Catalysts

[0141] Carbon (wt%) Nitrogen (wt%) Oxygen (wt%) Hydrogen (wt%) Preparation Example 1 79.3 10.6 3.7 1.9 Preparation Example 2 78.2 10.0 4.3 1.1 Preparation Example 3 78.5 9.2 3.3 1.3 Preparation Example 4 77.3 10.1 3.2 1.9 Preparation Example 5 79.1 8.3 3.3 1.8 Preparation Example 6 80.6 9.3 3.2 1.4 Comparative Example 1 84.6 1.7 5.2 1.9 Comparative Example 2 81.6 9.0 2.9 1.1

[0142] Elemental analysis results show that nitrogen from chitosan can be effectively incorporated into carbon materials during the synthesis of carbon-based catalysts, with the synthesized doped carbon material containing approximately 10 wt% nitrogen. In Comparative Example 1, which did not include chitosan, the resulting carbon material had a lower nitrogen content, indicating that the above synthesis method can effectively incorporate nitrogen from chitosan into carbon materials.

[0143] 2. Quantitative detection of surface functional groups on catalysts

[0144] The surface groups of the prepared catalyst were quantitatively detected using the Boehm titration method, as follows:

[0145] Preparation:

[0146] 1. Boil deionized water in an oil bath at 160°C for a few minutes, then seal and store.

[0147] 2. Prepare standard titration solutions of NaOH, HCl, Na2CO3, and NaHCO3, and determine the concentration of the standard titration solutions.

[0148] Boehm titration:

[0149] 1. Weigh out three samples of approximately 1.0g each and place them in three stoppered conical flasks (made of plastic and thoroughly dried). Add 50mL of 0.05mol / L NaOH, Na2CO3, and NaHCO3 solutions to each flask.

[0150] 2. Place the conical flask on a shaker and shake for 4 hours, then let it stand at room temperature for 24 hours (generally, the longer the better).

[0151] 3. Filter the activated carbon slurry once and take 20 mL of the filtrate.

[0152] 4. Add 20 mL of 0.05 mol / L hydrochloric acid to 20 mL of filtrate (add 40 mL of hydrochloric acid to the filtrate containing Na2CO3, and boil again to remove CO2 from the filtrate containing Na2CO3 or NaHCO3 after adding hydrochloric acid).

[0153] 5. Using phenolphthalein as an indicator, back-titrate excess acid with 0.05 mol / L standard NaOH solution until the solution turns slightly red.

[0154] Alkali consumption:

[0155] a=(V*CNaOH+20*C0-20*CHCl)*2.5 / M(NaOH,NaHCO3 calculation formula)

[0156] a=(V*CNaOH+20*C0-40*CHCl)*2.5 / M(Na2CO3 calculation formula)

[0157] Explanation of the calculation formula:

[0158] The concentration C0 in the formula is based on the equivalent concentration. Since Na2CO3 is a diprotic base, when calculating Na2CO3, C0 should be the molar concentration of Na2CO3 multiplied by 2.

[0159] V is the volume of NaOH consumed, C0 is the concentration of the added alkali solution, CHCl is the concentration of the hydrochloric acid solution used, and M is the mass of activated carbon.

[0160] calculate:

[0161] The number of carboxyl groups is represented by the amount of NaHCO3 consumed, aNaHCO3; the number of lactone groups is represented by the difference between the amounts of Na2CO3 and NaHCO3 consumed, aNa2CO3 - aNaHCO3; the number of phenolic hydroxyl groups is represented by the difference between the amounts of NaOH and Na2CO3 consumed, aNaOH - aNa2CO3.

[0162] Table 2 below shows the surface group number analysis results of the catalyst products prepared in Preparation Examples 1-6 and Comparative Examples 1-2.

[0163] Table 2: Number of functional groups on catalyst surface

[0164]

[0165] As shown in Table 2 above, the doped carbon catalysts synthesized in this invention all possess abundant surface groups. The amounts of carboxyl groups, lactone groups, and phenolic hydroxyl groups on the catalyst surface are approximately 0.5-0.6 mmol / g, 0.6-0.7 mmol / g, and 0.1 mmol / g, respectively. In Comparative Example 2, which did not use acid or oxidant treatment, the amounts of carboxyl groups, lactone groups, and phenolic hydroxyl groups in the obtained carbon material were 0.33 mmol / g, 0.21 mmol / g, and 0.06 mmol / g, respectively, which are significantly lower than the contents of other carbon materials described in this patent application. This indicates that acid / oxidant treatment can greatly enrich the number of groups on the surface of carbon materials.

[0166] 3. Testing of the adsorption capacity of catalyst products

[0167] The NH3-TPR characterization of the catalyst product was performed on a Micromeritics AutoChem 2920 chemisorption analyzer. The specific experimental procedure was as follows: 0.1 g of sample was placed in a U-shaped quartz tube and purged at 150 °C for 2 h in an Ar atmosphere. Then, the temperature was lowered to 100 °C, and 5 wt% NH3 / Ar mixture was adsorbed at 100 °C for 2 h. Next, the physicoadsorbed ammonia was purged under an Ar atmosphere for 1 h. After leveling the baseline, the temperature was increased to 800 °C at a rate of 10 °C / min. The NH3 signal was recorded using a TCD detector. The results are as follows: Figure 2 As shown.

[0168] from Figure 2 As shown in the figure above, the NH3-TPD comparison results between catalyst 6 and control catalyst 2 reveal that control catalyst 1 exhibits a significant NH3 desorption peak at 200℃, indicating certain weakly acidic sites. Control catalyst 2, in addition to the NH3- desorption peak near 200℃, also shows desorption peaks at higher temperatures (around 440℃), indicating stronger acidity. Catalyst 6, however, shows a stronger NH3 desorption peak at 230℃. This demonstrates that acid / oxidant treatment significantly enhances the acidity of the catalyst surface, and the significantly increased NH3 desorption temperature indicates stronger acidity and higher acid content. This result is consistent with the catalyst surface group content results obtained from the Boehm titration test, showing that acid / oxidant treatment can significantly increase the number of groups on the catalyst surface, thereby enhancing the surface acidity.

[0169] Test Implementation Examples

[0170] The preparation method of sebacate by continuous synthesis in a fluidized bed reactor is as follows:

[0171] The fluidized bed reactor has the following dimensions: upper section inner diameter 100 mm, outer diameter 108 mm, length 300 mm; lower section inner diameter 40 mm, outer diameter 48 mm, length 200 mm; and is filled with 300 g of catalyst prepared according to Examples 1-6 and Comparative Examples 1-2. First, fluidizing gas is introduced into the reactor at a flow rate of 2-3 L / min using a mass flow meter to create a fluidized state for the catalyst. Then, the reactor is heated to 400°C in a furnace to activate the catalyst. Next, the temperature of the reactor is adjusted to the reaction temperature, and the raw materials are fed into the reactor through a solid feeder. Under a nitrogen-fluidized gas atmosphere and with catalyst catalysis, the reaction produces a product containing sebacate. After condensation and gas-liquid separation, the sebacate product is collected for testing.

[0172] The catalysts obtained in Preparation Examples 1-6 and Comparative Examples 1-2 were used to catalyze the amination and dehydration of sebacate to prepare sebaonitrile. Their catalytic efficiency and selectivity for the target product sebaonitrile were tested. The test results are shown in Table 3 below.

[0173] Table 3 Results of different embodiments

[0174]

[0175]

[0176] As can be seen from the table above, the catalyst described in this invention exhibits a high conversion rate of sebacic acid to sebaconitrile during the catalytic conversion process, with conversion rates generally exceeding 99% (Examples 1-6). It also demonstrates high selectivity for the target product, sebaconitrile, and this is further enhanced by lowering the reaction temperature to 300°C and increasing the space velocity to 1 h. -1 Under the conditions described in Examples 7-8, the selectivity for sebaonitrile can reach >99%. Comparing Example 8 with Comparative Examples 3-4, it can be seen that further decreases in temperature and further increases in space velocity both reduce the sebaonitrile yield. Comparing Example 8 with Comparative Examples 5-7, it can be seen that sebaonitrile yields comparable to those obtained with urea as a nitrogen source can be achieved using ammonia or ammonium carbonate as nitrogen sources; the yield is slightly lower when ammonia water is used as an ammonia source.

[0177] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing sebacite from sebaic acid via a continuous selective dehydration reaction, the method comprising the following steps: in the presence of a catalyst, a certain proportion of sebaic acid and a nitrogen source are mixed, and then fed as solid powder with fluidized gas, or sebaic acid is fed as solid powder with fluidized gas, and a liquid or gaseous nitrogen source is introduced through a pipeline with a certain proportion of fluidized gas; under a certain pressure, the two react in a reactor in gaseous form and then leave the reactor with the fluidized gas to obtain a mixture of sebacite and inorganic salt, which is then obtained by extraction, separation, and vacuum distillation to obtain a high-purity sebacite product; The reactor is a fluidized bed reactor; The catalyst is prepared by a method comprising the following steps: Step 1) After the dried biomass raw material is crushed by a pulverizer, it is added together with the solid acid catalyst and ball-milled into a fine powder of 200-400 mesh. The powder is then added to a reaction vessel, distilled water is added, the reaction vessel is sealed, and the mixture is heated to 150-250℃ for hydrolysis reaction for 4-10 hours. After the reaction is completed, the temperature is lowered, the pressure is released, and the mixture is filtered under reduced pressure. The filtrate is then distilled and concentrated to 20% of its original volume to obtain a concentrated solution. Step 2) Add the acid solution to the concentrated solution described in Step 1 under vigorous stirring. After mixing evenly, add chitosan and transfer to a hydrothermal reactor. Perform hydrothermal treatment at 160-220℃ for 4-20 hours. After cooling and depressurization, wash the obtained product three times with anhydrous ethanol and deionized water respectively, and then dry it at 110℃ for 12 hours to obtain the doped carbon material. Step 3) Add alkali to the doped carbon material obtained in step 2, stir and mix evenly, place it in a tube furnace, heat to 300-700℃ under an inert gas atmosphere for carbonization treatment for 4-20h. After carbonization, cool down, wash the obtained material with distilled water until the filtrate is neutral, and dry at 110℃ for 12h. Step 4) Mix the doped carbon material obtained in Step 3 with acid or oxidant and stir evenly. Heat to 60-90℃ for 4-10 hours. After treatment, cool down and filter. Wash the material with distilled water until the filtrate is neutral. Dry at 110℃ for 12 hours.

2. The method for preparing sebacate according to claim 1, characterized in that, The nitrogen source is urea.

3. The method for preparing sebacate according to claim 1, characterized in that, The molar ratio of sebacic acid to nitrogen source is 1:(2-8).

4. The method for preparing sebacate according to claim 3, characterized in that, The molar ratio of sebacic acid to nitrogen source is 1:2, 1:4, 1:5, 1:6, 1:7 or 1:

8.

5. The method for preparing sebacate according to claim 1, characterized in that, The reaction temperature is 250-400℃.

6. The method for preparing sebacate according to claim 1, characterized in that, The reaction temperature is 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃ or 360℃.

7. The method for preparing sebacate according to claim 1, characterized in that, The reaction temperature is 300-330℃.

8. The method for preparing sebacate according to claim 1, characterized in that, The fluidizing gas velocity during the reaction process is 1–5 L / min.

9. The method for preparing sebacate according to claim 1, characterized in that, The fluidizing gas rates during the reaction process were 1 L / min, 2 L / min, 3 L / min, 4 L / min, and 5 L / min.

10. The method for preparing sebacate according to claim 1, characterized in that, The fluidization gas velocity during the reaction process is 2–3 L / min.

11. The method for preparing sebacate according to claim 1, characterized in that, The space velocity during the reaction process is 0.05 h⁻¹. -1 ~5h -1 .

12. The method for preparing sebacate according to claim 1, characterized in that, The space velocity during the reaction process is 0.1 h⁻¹. -1 ~3h -1 .

13. The method for preparing sebacate according to claim 1, characterized in that, The fluidizing gas is one or more of nitrogen atmosphere, helium atmosphere, and argon atmosphere.

14. The method for preparing sebacate according to claim 1, characterized in that, The method is carried out under a reaction pressure of atmospheric pressure to 4 MPa.

15. The method for preparing sebacate according to claim 1, characterized in that, The method is carried out under a reaction pressure of atmospheric pressure to 2 MPa.

16. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, After the reaction in step 1) is completed, the filter cake obtained by filtration contains the solid acid catalyst. The filter cake is calcined at 350-550℃ for 3-6 hours to remove organic matter and obtain the solid acid catalyst. The obtained solid acid catalyst can be recycled.

17. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 1), the biomass material includes one or more of corn cobs, corn stalks, sawdust, peanut shells, and bamboo shoots.

18. The method for preparing sebacate according to claim 17, characterized in that, In the preparation method of the catalyst, in step 1), the biomass material includes one or more of corn cobs, corn stalks, and peanut shells.

19. The method for preparing sebacate according to claim 17, characterized in that, In the method for preparing the catalyst, in step 1), the biomass material includes one or more of corn cobs and corn stalks.

20. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 1), the solid acid catalyst includes one or more of the following: silicon dioxide, γ-alumina, zirconium dioxide, cerium dioxide, tungsten trioxide, niobium pentoxide, zeolite molecular sieve, and ion exchange resin.

21. The method for preparing sebacate according to claim 20, characterized in that, In the method for preparing the catalyst, in step 1), the solid acid catalyst includes one or more of silicon dioxide, γ-alumina, tungsten trioxide, niobium pentoxide, zeolite molecular sieve, and ion exchange resin.

22. The method for preparing sebacate according to claim 21, characterized in that, In the method for preparing the catalyst, in step 1), the solid acid catalyst includes one or more of γ-alumina, zeolite molecular sieves, and ion exchange resins.

23. The method for preparing sebacate according to any one of claims 20 to 22, characterized in that, The zeolite molecular sieve includes one or more of HZSM5, HZSM11, HY, Hβ, HMOR, and SAPO-34.

24. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 1), the mass ratio of distilled water to biomass raw material is 50:1-2:

1.

25. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 1), the mass ratio of distilled water to biomass raw material is 20:1-5:

1.

26. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 1), the hydrolysis reaction temperature is 120-250℃.

27. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 1), the hydrolysis reaction temperature is 150-220℃.

28. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 1), the hydrolysis reaction temperature is 160-210℃.

29. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 1), the hydrolysis reaction time is 4-10 h.

30. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 1), the hydrolysis reaction time is 4-6 hours.

31. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 1), the mass concentration of the concentrated solution is 10%-30%.

32. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 1), the mass concentration of the concentrated solution is 10%-20%.

33. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 2), the acid is selected from one or more of formic acid, acetic acid, propionic acid, and hydrochloric acid.

34. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 2), the mass concentration of the acid solution is 1%-30%.

35. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 2), the mass concentration of the acid solution is 3%-10%.

36. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 2), the mass ratio of the acid solution to the concentrated solution is 1:1 to 10:

1.

37. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 2), the mass ratio of the acid solution to the concentrated solution is 1:1 to 5:

1.

38. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 2), the mass ratio of chitosan to concentrated solution is 1:10 to 1:

100.

39. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 2), the hydrothermal treatment temperature is 160-220℃.

40. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 2), the hydrothermal treatment temperature is 180-210℃.

41. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 2), the hydrothermal treatment time is 4-20 h.

42. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 2), the hydrothermal treatment time is 5-10 hours.

43. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 3), the base is selected from one or more of sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, and potassium ethoxide.

44. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 3), the mass ratio of the alkali to the doped carbon material is 1:1-10:

1.

45. The method for preparing sebacate according to claim 1, characterized in that, In the catalyst preparation method, in step 3), the mass ratio of the alkali to the doped carbon material is 1:1-5:

1.

46. ​​The method for preparing sebacate according to claim 1, characterized in that, In the catalyst preparation method, in step 3), the mass ratio of the alkali to the doped carbon material is 1:1 to 3:

1.

47. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 3), the inert gas used in the carbonization process includes one or more of nitrogen, helium, and argon.

48. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 3), the inert gas used in the carbonization process includes one or more of nitrogen and argon.

49. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 4), the acid is one or more of sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, and phosphoric acid.

50. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 4), the oxidant is one or more of hydrogen peroxide (30 wt%) and sodium hypochlorite (6% available chlorine).

51. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 4), the mass ratio of the acid to the carbon material is 1:1-10:

1.

52. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 4), the mass ratio of the oxidant to the carbon material is 1:1 to 10:

1.

53. The method for preparing sebacate according to claim 1, characterized in that, In the preparation method of the catalyst, in step 4), the processing temperature is 60-90℃.

54. The method for preparing sebacate according to claim 1, characterized in that, In the method for preparing the catalyst, in step 4), the treatment time is 4-10 h.

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