CN115888847A - Carbon-nitrogen material, preparation method and application thereof, and supported catalyst and application thereof - Google Patents
Carbon-nitrogen material, preparation method and application thereof, and supported catalyst and application thereof Download PDFInfo
- Publication number
- CN115888847A CN115888847A CN202111157290.7A CN202111157290A CN115888847A CN 115888847 A CN115888847 A CN 115888847A CN 202111157290 A CN202111157290 A CN 202111157290A CN 115888847 A CN115888847 A CN 115888847A
- Authority
- CN
- China
- Prior art keywords
- carbon
- nitrogen
- nitrogen material
- oxygen
- roasting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Landscapes
- Carbon And Carbon Compounds (AREA)
- Catalysts (AREA)
Abstract
The invention provides a biomass-based carbon-nitrogen material, a preparation method and application thereof, and a supported catalyst and application thereof, wherein the carbon-nitrogen material contains carbon element, nitrogen element and oxygen element, and the specific surface area is 300m 2 Pore volume below 0.4cm 3 The ratio of the carbon atoms to the carbon atoms is less than g. The carbon and nitrogen material prepared by the method has specific surface area andthe pore volume can be regulated and controlled, the nitrogen content is high, and the like. The carbon-nitrogen material prepared by the method is used as a carrier, a metal active component is loaded, and the loaded metal catalyst can be prepared after activation, can be used for catalyzing selective hydrogenation reaction of unsaturated functional groups, and particularly obtains better technical effect in crude terephthalic acid hydrogenation refining reaction after palladium loading.
Description
Technical Field
The invention belongs to the technical field of novel carbon material preparation, and particularly relates to a biomass-based carbon-nitrogen material, a preparation method and application thereof, and a supported catalyst and application thereof.
Background
The biomass-based raw materials (cellulose, starch, glucose, fructose, sucrose or rice hulls, bamboos and the like) are widely available in the nature as green renewable resources, are cheap and easily available, and are ideal carbon sources for synthesizing carbon materials. The carbon material synthesized by the biomass-based raw material can be directly used as a catalyst and also can be used as a carrier of a supported metal catalyst, has excellent catalytic performance, and shows better application prospects in the fields of catalytic hydrogenation, energy storage, lithium ion batteries, water treatment and the like.
The method for preparing the carbon material by taking biomass as a carbon source mainly comprises a direct carbonization method, a hydrothermal carbonization method or a template method and the like. In order to obtain a carbon material with a porous structure and high strength, the main defects of the traditional preparation process are high energy consumption, complex process and the like. The use of the template method for preparing the porous carbon material not only increases the production cost, but also causes the destruction of the pore structure and the surface functional group, etc. in the process of removing the template. With the advent of new material production methods in recent years, researchers have begun trying a wide variety of raw materials and new techniques for synthesizing different types of carbon materials.
CN106783209B takes glucose, thiourea and sodium dodecyl sulfate as raw materials, and a porous carbon material is prepared by a hydrothermal and KOH activation method, and the material is a hollow structure formed by polymer beads and can be applied to the field of supercapacitors as an electrode material.
CN108262077A reports a high-strength nitrogen-doped carbon monolithic catalytic material with hierarchical pores, which is prepared by using nitrogen-containing organic matters and saccharides as precursors through pre-carbonization and carbonization processes, and can be used in the fields of chloroethylene preparation by acetylene method, electro-catalysis and the like.
Disclosure of Invention
The invention aims to provide a carbon-based new material with a new structure and a preparation method thereof aiming at the defects of the existing carbon material preparation technology.
According to a first aspect of the present invention, there is provided a biomass-based carbon-nitrogen material comprising carbon, nitrogen and oxygen, and having a specific surface area of 300m 2 Per gram or less, pore volume of 0.4cm 3 The ratio of the carbon atoms to the carbon atoms is below g.
According to a second aspect of the invention, the invention provides a method for preparing the biomass-based carbon and nitrogen material, which comprises the following steps:
(1) Forming a carbon source, a nitrogen source and an alkali metal salt into an aqueous solution, carrying out hydrothermal reaction under a sealed condition, and then cooling, washing and drying to obtain a solid sample;
(2) And roasting the solid sample in an oxygen-containing atmosphere.
According to a third aspect of the invention, the invention provides the use of a carbon and nitrogen material according to the invention as a catalyst carrier.
According to a fourth aspect of the invention, there is provided a supported catalyst having a support comprising a carbon and nitrogen material according to the invention, preferably the active component of the supported catalyst is a metal active component, more preferably the active component is palladium.
According to a fifth aspect of the invention, there is provided the use of a carbon nitrogen material according to the invention or a catalyst according to the invention in selective hydrogenation of unsaturated functional groups, preferably in a crude terephthalic acid hydrofinishing reaction.
The carbon and nitrogen material prepared by the method has the characteristics of controllable specific surface area and pore volume, high nitrogen content and the like, the method is different from the carbon pellet and other structures prepared by the traditional hydrothermal method, and the obtained sample has special microstructure and compact structure.
The carbon-nitrogen material prepared by the method is used as a carrier, a metal active component is loaded, and the loaded metal catalyst can be prepared after activation, can be used for catalyzing selective hydrogenation reaction of unsaturated functional groups, and particularly obtains better technical effect in crude terephthalic acid hydrogenation refining reaction after palladium loading.
Compared with the prior art, the invention has the following beneficial effects:
(1) The method has simple process, the specific surface area, pore volume, nitrogen content and the like of the obtained carbon-nitrogen material are controllable, and the method can be realized by controlling the proportion of a carbon source, a nitrogen source and the like and the preparation conditions;
(2) The carbon source related by the invention can be obtained from renewable resources, has wide sources and low price, and is beneficial to popularization of planning application.
(3) The carbon and nitrogen material prepared by the method has a compact structure, and the nitrogen doping amount can be accurately regulated and controlled according to specific requirements.
(4) The carbon and nitrogen material obtained by the invention is an excellent catalyst carrier, and can be widely used for preparing a supported metal catalyst.
Specifically, for example, the palladium catalyst prepared by the carbon and nitrogen carrier obtained by the method is used for the hydrofining reaction of crude terephthalic acid, the activity and the stability of the palladium catalyst are superior to those of the traditional coconut shell carbon-supported palladium catalyst, the advantage of high selectivity generation of the intermediate product 4-hydroxymethyl benzoic acid is also achieved, and the energy consumption of subsequent product separation and purification is reduced.
Drawings
FIG. 1 is a scanning electron micrograph of a sample prepared in example 5;
FIG. 2 is a scanning electron micrograph of a sample prepared in example 5at an enlarged observation magnification;
FIG. 3 is a scanning electron micrograph of a sample prepared in comparative example 1;
FIG. 4 is a scanning electron micrograph of a sample prepared in comparative example 5.
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and these ranges or values should be understood to encompass values close to these ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.
The invention provides a biomass-based carbon-nitrogen material, which contains carbon element, nitrogen element and oxygen element, and has a specific surface area of 300m 2 Pore volume below 0.4cm 3 The ratio of the carbon atoms to the carbon atoms is less than g. The carbon and nitrogen material prepared by the method has the characteristics of controllable specific surface area and pore volume, high nitrogen content and the like, the method is different from the carbon pellet and other structures prepared by the traditional hydrothermal method, and the obtained sample has special microstructure and compact structure.
According to the invention, the microstructure of the carbon and nitrogen material is preferably a compact structure with a massive shape. Compared with the loose structure of the conventional nano carbon spheres, the carbon and nitrogen material has the advantages of better dispersion and stabilization of the active metal nano particles. The material of the invention has a compact structure, is not composed of conventional carbon nanospheres, and has a specific surface area of 5m 2 A ratio of,/g or more, preferably60-280m 2 Per g, pore volume is preferably 0.01-0.40cm 3 (ii) in terms of/g. The specific surface area and the pore volume of the carbon and nitrogen material can be accurately regulated and controlled through reaction parameters.
According to the invention, the nitrogen element is preferably present in an amount of 6 to 15at.%, the remainder being carbon and oxygen, based on the total weight of the carbon and nitrogen material.
According to the invention, it is preferred that the content of nitrogen is 7.5-12.5at.%, the content of carbon is 80-95at.%, and the content of oxygen is 5-10at.%, based on the total weight of the carbon and nitrogen material.
The carbon and nitrogen material with the characteristics can achieve the aim of the invention, the preparation method of the carbon and nitrogen material is not particularly required, and the invention provides the preparation method of the biomass-based carbon and nitrogen material, which comprises the following steps:
(1) Forming a carbon source, a nitrogen source and alkali metal salt into an aqueous solution, carrying out hydrothermal reaction under a sealed condition, and then cooling, washing and drying to obtain a solid sample;
(2) And roasting the solid sample in an oxygen-containing atmosphere. By means of the method according to the invention, a carbon and nitrogen material having the features according to the invention can be produced.
According to the present invention, the hydrothermal reaction conditions can be selected in a wide range, and for the present invention, it is preferable that the hydrothermal reaction conditions in step (1) include: the temperature is 140 to 200 ℃ and preferably 160 to 180 ℃.
According to the present invention, the time of the hydrothermal reaction can be determined according to the temperature, and particularly, the time of the hydrothermal reaction is preferably 2 to 10 hours, and preferably 4 to 7 hours.
According to the present invention, the amount of each substance can be selected within a wide range, and for the present invention, the mass ratio of the carbon source, nitrogen source and alkali metal salt is preferably 5 to 20:1-6:1, preferably 10 to 15:1-6:1.
according to the present invention, the concentration of the carbon source in the aqueous solution can be selected within a wide range, and for the present invention, it is preferable that the concentration of the carbon source in the aqueous solution in the step (1) is 8 to 12% by weight.
According to the present invention, the conditions for calcination can be selected widely, and for the present invention, it is preferable that in step (2), the calcination conditions include: the temperature is 450 to 950 ℃, preferably 650 to 800 ℃.
According to the present invention, the time for calcination is determined depending on the temperature, and for the present invention, it is preferable that in the step (2), the calcination conditions include: the time is 0.5-3h, preferably 1-2h.
According to a preferred embodiment of the present invention, the preferred firing conditions include: in an oxygen-containing atmosphere, step-by-step roasting is adopted, firstly pretreatment is carried out for 0.5-1h at the low temperature of 200-300 ℃, and then the temperature is raised to 450-950 ℃ for roasting for 0.5-3h.
According to a preferred embodiment of the invention, the firing is carried out in a tube furnace.
According to a preferred embodiment of the present invention, the oxygen concentration in the oxygen-containing atmosphere is 15 to 25% by volume.
According to the present invention, the oxygen-containing atmosphere is, for example, air, nitrogen, or a mixed gas of argon and oxygen, or the like. An air atmosphere is preferred.
In the invention, the carbon source type is wide in selectable range, and aiming at the invention, the carbon source can be various biomass carbon sources, specifically, the carbon source is one or more of glucose, fructose, xylose, sucrose, chitosan and cellulose; for the present invention, glucose and/or fructose are preferred.
In the present invention, the nitrogen source is selected from a wide range, and for the purposes of the present invention, urea and/or melamine are preferred, and urea is more preferred.
In the present invention, the kind of the alkali metal salt is widely selected, and for the present invention, one or more of potassium sulfate, sodium carbonate, potassium carbonate, sodium chloride, and potassium chloride is preferable, one or more of potassium sulfate, sodium carbonate, and potassium carbonate is more preferable, and sodium sulfate is more preferable.
According to a preferred embodiment of the invention, the method of the invention comprises:
(1) Dissolving a carbon source, a nitrogen source and alkali metal salt in water according to a ratio, transferring the mixture into a reaction kettle, reacting for 2-10h at 140-200 ℃, naturally cooling, washing and drying to obtain a solid sample;
(2) And (3) placing the solid sample in a tubular furnace, and roasting for 0.5-3h at 450-950 ℃ in an oxygen-containing atmosphere.
According to a preferred embodiment of the invention, the method of the invention comprises: dissolving a carbon source, a nitrogen source and potassium sulfate in water according to a certain proportion, then transferring the mixture into a reaction kettle, reacting for 2-10h at 140-200 ℃, naturally cooling, washing and drying to obtain a solid sample; and roasting the solid sample for 0.5-3h at 450-950 ℃ in an air atmosphere to obtain the biomass-based carbon-nitrogen material.
The carbon and nitrogen material with the special property of the invention can be prepared by adopting the method of the invention. Is particularly suitable for being used as a catalyst carrier.
The invention provides an application of the carbon-nitrogen material as a catalyst carrier.
The invention provides a supported catalyst, the carrier of the supported catalyst contains the carbon-nitrogen material, preferably, the active component of the supported catalyst is a metal active component, the optional range of the type of the metal active component is wide, and for the invention, the active component is preferably palladium.
The supported catalyst of the invention is particularly suitable for the application in the selective hydrogenation reaction of unsaturated functional groups, preferably in the hydrofining reaction of crude terephthalic acid.
The supported catalyst can be used for catalyzing selective hydrogenation reaction of unsaturated functional groups. Preferably, the palladium-carbon catalyst can be prepared by loading the active component palladium, and is preferably used for catalyzing the hydrofining reaction of crude terephthalic acid.
In order to more clearly illustrate the technical solution of the present invention, the following embodiments are exemplified.
The solid sample is roasted and activated for etching the surface of carbon, burning off amorphous carbon, reconstructing C-C and C-N bonds, forming some pore structures and finally forming the carbon-nitrogen material with stable structure. Therefore, there is a loss of quality, defined herein as yield, compared to the post-firing and pre-firing. The yield of a sample refers to the mass of the sample after calcination as a percentage of the mass of the sample before calcination.
Example 1
Weighing 6.0g of glucose, 1.5g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 160 ℃ for 6 hours, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 650 ℃ for 1h in air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 41.1%.
Example 2
Weighing 6.0g of fructose, 1.5g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting for 6 hours at 160 ℃, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 650 ℃ for 1h in air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 42.3%.
Example 3
Weighing 6.0g of fructose, 1.5g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 180 ℃ for 6 hours, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 750 ℃ for 1h in an air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 38.2%.
Example 4
Weighing 6.0g of glucose, 0.5g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting for 6 hours at 180 ℃, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 750 ℃ for 1h in an air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 38.7%.
Example 5
Weighing 6.0g of glucose, 1.5g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 180 ℃ for 6 hours, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 750 ℃ for 1h in an air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 35.3%. Scanning electron micrographs of the samples are shown in FIGS. 1 and 2. Fig. 1 shows that the synthesized carbon and nitrogen material consists of a dense block structure, while fig. 2 is a morphology of fig. 1 at a further magnification, it can be seen that the surface of the synthesized carbon and nitrogen material is flat at the microscopic scale, and no significant macroporous structure is observed.
Example 6
Weighing 6.0g of glucose, 3.0g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting for 6 hours at 180 ℃, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 750 ℃ for 1h in an air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 40.5%.
Example 7
Weighing 6.0g of glucose, 1.5g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 180 ℃ for 6 hours, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 850 ℃ for 1h in the air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 43.2%.
Example 8
Weighing 6.0g of glucose, 0.5g of melamine and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 180 ℃ for 6 hours, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 750 ℃ for 1h in an air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 43.7%.
Example 9
Weighing 6.0g of glucose, 1.5g of melamine and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 180 ℃ for 6 hours, naturally cooling, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 750 ℃ for 1h in an air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material with the yield of 42.9%.
Example 10
The procedure of example 5 was followed except that the carbon source was changed to xylose as the carbon source and the other conditions were the same.
Example 11
The procedure is as in example 5, except that the solution reaction conditions are changed and maintained at 140 ℃ for 6h, the other conditions being the same.
Example 12
The same procedure as in example 5 was followed, except that the kind of the metal salt was changed, sodium carbonate was added, and the other conditions were changed. The yield of the resulting carbon-nitrogen material was 33.6%.
Example 13
The procedure of example 5 was followed except that the calcination was carried out in different ways, by stepwise calcination, first at 200 ℃ for 0.5h and then at 750 ℃ for 1h, and the other conditions were the same.
Example 14
The procedure of example 5 was followed except that the calcination was carried out in different ways, by stepwise calcination, first at 300 ℃ for 0.5h and then at 750 ℃ for 1h, and the other conditions were the same.
Example 15
The same procedure as in example 5 was followed, except that the amount of the carbon source added was changed to 4g of glucose, and the conditions were changed. The yield of the resulting carbon-nitrogen material was 21.7%.
Example 16
The same procedure as in example 5 was followed, except that the amount of the carbon source added was changed to 9g of glucose, and the conditions were changed. The yield of the resulting carbon-nitrogen material was 23.4%.
Comparative example 1
Weighing 6.0g of glucose and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 180 ℃ for 6 hours, washing and drying to obtain a solid sample; and (3) roasting the obtained solid sample in a tubular furnace at 750 ℃ for 1h in air atmosphere, and naturally cooling to room temperature to obtain the biomass-based carbon-nitrogen material, wherein the yield is 17.3%, and the scanning electron microscope image of the sample is shown in figure 3.
Comparative example 2
Weighing 6.0g of glucose, 1.5g of urea and 0.5g of sodium sulfate, dissolving in 60.0g of water, transferring to a reaction kettle, reacting at 180 ℃ for 6 hours, naturally cooling, washing and drying to obtain a nitrogen-doped carbon sample, wherein the sample is not subjected to air atmosphere roasting treatment subsequently.
Comparative example 3
Weighing 1.0g of commercial coconut shell activated carbon with 4-6 meshes, crushing to obtain particles with 20-40 meshes, and taking the obtained solid as a carrier of the palladium catalyst.
Comparative example 4
And (2) adopting urea as a nitrogen source, mixing 6g of coconut shell carbon with 3g of urea, placing the mixture in a tube furnace, and roasting the mixture for 1h at 750 ℃ in a nitrogen atmosphere to obtain the nitrogen-doped coconut shell carbon. The scanning electron micrograph of the sample is shown in FIG. 4.
Scanning electron micrographs of the samples of comparative example 5 (FIGS. 1 and 2) and comparative example 1 (FIG. 3) illustrate that the addition of nitrogen source greatly changes the morphology of the carbon material, and the carbon-nitrogen material obtained without the addition of urea consists of carbon globules of varying sizes (see FIG. 3); after the urea is added, the obtained carbon-nitrogen material is not composed of a polymer bead structure, but forms a compact block structure. The surface rich macroporous structure is observed in the micro-morphology (fig. 4) of the nitrogen-doped coconut carbon in comparative example 4.
The same preparation procedure was used with PdCl using the samples obtained in examples 1-16 and comparative examples 1-4 as carriers, respectively 2 The water solution is used as a precursor, and the palladium catalyst with the load of 0.4wt.% is obtained after room-temperature impregnation and 5% of sodium formate reduction treatment at 50 ℃ for 2h.
The fresh catalysts prepared in examples 1 to 16 and comparative examples 1 to 4 were used for evaluation of the performance of hydrorefining crude terephthalic acid, and the evaluation results are shown in Table 2.
The specific reaction conditions are as follows: the catalyst loading was 2.0 g, crude terephthalic acid 30.0 g (with a 4-CBA content of about 3300 ppm), aqueous solution 1000.0ml, reaction pressure 5.5MPa, reaction temperature 280 ℃ and reaction time 1.0h. And carrying out quantitative analysis on the liquid product after reaction by using a high performance liquid chromatography and an ultraviolet detector. The activity of the catalyst was evaluated by calculating the residual 4-CBA content, the lower the residual 4-CBA content, the higher the catalytic efficiency of the catalyst.
The fresh catalysts obtained from the preparation of the supports in examples 1 to 16 and comparative examples 1 to 4 were subjected to an aging treatment: specifically, a fresh palladium catalyst was added to a high-pressure reactor under conditions similar to the initial performance evaluation conditions and process of the catalyst, except that the reaction time was extended to 17 hours, and then the catalyst after the reaction was filtered, washed, and dried to obtain an aged catalyst, and then the hydrofining performance was evaluated again, and the results are shown in table 2. All the treatment conditions of the obtained palladium catalyst and the hydrogenation performance evaluation conditions of the catalyst are the same.
TABLE 1 physicochemical Properties of different carbon and nitrogen materials
Comparing the physicochemical properties of examples 1-16 and comparative examples 1 and 2 (see table 1), it is confirmed that the biomass-based carbon nitrogen material prepared by the invention has adjustable specific surface area and pore volume and high nitrogen content. Comparative example 1 in which no nitrogen source was added, the resulting carbon material was not only extremely low in specific surface area (<5m 2 Per gram), non-porous structure, very low nitrogen content. In comparative example 2, although the nitrogen source was added and the nitrogen content in the obtained sample was high, the specific surface area of the obtained sample was less than 5m due to the lack of the air firing step 2 (iv) g. Therefore, the invention provides a carbon-nitrogen composite material which has a porous structure, high nitrogen content and a compact structure and can be obtained through hydrothermal reaction and air roasting under a proper raw material ratio.
TABLE 2
The purpose of the aging treatment was to examine the stability of the catalyst. The reduction in the conversion of the catalyst after the aging treatment reflects the stability of the catalyst. The lower the loss of conversion after aging, the better the stability of the catalyst. As can be seen from the test results in Table 2, the catalysts prepared by the present invention all have higher conversion efficiency of 4-CBA. Compared with the traditional coconut shell based activated carbon supported palladium catalyst, the comparative example 3, the nitrogen-free carbon and nitrogen material supported palladium catalyst in the comparative example 1 and the three catalysts which are not calcined by air in the comparative example 2, a series of biomass based carbon and nitrogen material supported palladium catalysts obtained by the method have higher conversion efficiency of 4-CBA and good stability. In conclusion, the invention provides a novel carbon and nitrogen material, a preparation method and a catalytic application, and experiments prove that the carbon and nitrogen material loaded with palladium obtains better technical effects when used for hydrofining crude terephthalic acid.
TABLE 3
| Conversion of 4-CBA (%) | Selectivity of 4-HMBA (%) | |
| Example 1 | 98.6 | 67.3 |
| Comparative example 1 | 96.7 | 10.2 |
| Comparative example 2 | 97.9 | 23.4 |
| Comparative example 3 | 97.4 | 9.3 |
| Comparative example 4 | 97.8 | 20.1 |
In addition, as can be seen from the results of the catalytic performance evaluation in table 3, the palladium catalyst supported on the biomass-based carbon nitrogen material prepared by the invention can be used for the hydrofining reaction of crude terephthalic acid, not only can efficiently convert the impurity 4-CBA into hydrogen, but also can convert the 4-CBA into the intermediate product 4-HMBA (hydroxymethylbenzoic acid) with high selectivity, and the solubility of the hydrogenated product 4-HMBA in water is far greater than that of the hydrogenated product p-toluic acid (4-PT). The high-selectivity 4-HMBA obtained is beneficial to the separation and purification of subsequent products to obtain the high-purity terephthalic acid, so that the operation cost can be effectively reduced, and the energy consumption can be saved.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. The biomass-based carbon-nitrogen material is characterized by comprising carbon element, nitrogen element and oxygen element, and the specific surface area is 300m 2 Pore volume below 0.4cm 3 The ratio of the carbon atoms to the carbon atoms is less than g.
2. The carbon nitrogen material of claim 1,
the micro-morphology of the carbon and nitrogen material is a blocky compact structure;
the carbon-nitrogen material has a specific surface area of 5m 2 A specific surface area of 60 to 280m 2 (ii)/g; and/or
The pore volume of the carbon and nitrogen material is 0.01-0.40cm 3 (ii)/g; and/or
Based on the total weight of the carbon and nitrogen material, the content of nitrogen element is 6-15at.%, and the rest is carbon element and oxygen element;
preferably, the nitrogen is present in an amount of 7.5 to 12.5at.%, the carbon is present in an amount of 80 to 95at.% and the oxygen is present in an amount of 5 to 10at.%, based on the total weight of the carbon and nitrogen material.
3. The method for producing a biomass-based carbon nitrogen material according to claim 1 or 2, characterized by comprising:
(1) Forming a carbon source, a nitrogen source and an alkali metal salt into an aqueous solution, carrying out hydrothermal reaction under a sealed condition, and then cooling, washing and drying to obtain a solid sample;
(2) And roasting the solid sample in an oxygen-containing atmosphere.
4. The production method according to claim 3,
the hydrothermal reaction conditions in the step (1) comprise: the temperature is 140-200 ℃, preferably 160-180 ℃; and/or for a period of 2-10 hours, preferably 4-7 hours; and/or
The mass ratio of the carbon source, the nitrogen source and the alkali metal salt is 5-20:1-6:1, preferably 10 to 15:1-6:1; and/or
The concentration of the carbon source in the aqueous solution in the step (1) is 8-12 wt%.
5. The production method according to claim 3 or 4, wherein, in the step (2),
the roasting conditions include: the temperature is 450-950 ℃, preferably 650-800 ℃; and/or for a period of 0.5 to 3 hours, preferably 1 to 2 hours; and/or
Preferred firing conditions include: in an oxygen-containing atmosphere, step-by-step roasting is adopted, pretreatment is carried out for 0.5-1h at a low temperature of 200-300 ℃, and then the temperature is raised to 450-950 ℃ for roasting for 0.5-3h; and/or
The roasting is carried out in a tube furnace; and/or
The oxygen concentration in the oxygen-containing atmosphere is 15 to 25 vol%.
6. The production method according to any one of claims 3 to 5,
the carbon source is one or more of glucose, fructose, xylose, sucrose, chitosan and cellulose; preferably glucose and/or fructose; and/or
The nitrogen source is urea and/or melamine, preferably urea; and/or
The alkali metal salt is one or more of potassium sulfate, sodium carbonate, potassium carbonate, sodium chloride and potassium chloride, preferably one or more of potassium sulfate, sodium carbonate and potassium carbonate, and more preferably sodium sulfate.
7. The production method according to any one of claims 3 to 6, wherein the method comprises:
(1) Dissolving a carbon source, a nitrogen source and alkali metal salt in water according to a ratio, transferring the mixture into a reaction kettle, reacting for 2-10h at 140-200 ℃, naturally cooling, washing and drying to obtain a solid sample;
(2) And (3) placing the solid sample in a tubular furnace, and roasting for 0.5-3h at 450-950 ℃ in an oxygen-containing atmosphere.
8. Use of a carbon-nitrogen material according to claim 1 or 2 as a catalyst support.
9. A supported catalyst, characterized in that the carrier of the supported catalyst contains a carbon-nitrogen material according to claim 1 or 2, preferably the active component of the supported catalyst is a metal active component, more preferably the active component is palladium.
10. Use of the carbon-nitrogen material according to claim 1 or 2 or the catalyst according to claim 9 in selective hydrogenation of unsaturated functional groups, preferably in hydrofinishing of crude terephthalic acid.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111157290.7A CN115888847A (en) | 2021-09-30 | 2021-09-30 | Carbon-nitrogen material, preparation method and application thereof, and supported catalyst and application thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111157290.7A CN115888847A (en) | 2021-09-30 | 2021-09-30 | Carbon-nitrogen material, preparation method and application thereof, and supported catalyst and application thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115888847A true CN115888847A (en) | 2023-04-04 |
Family
ID=86490273
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111157290.7A Pending CN115888847A (en) | 2021-09-30 | 2021-09-30 | Carbon-nitrogen material, preparation method and application thereof, and supported catalyst and application thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115888847A (en) |
-
2021
- 2021-09-30 CN CN202111157290.7A patent/CN115888847A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108579788B (en) | Composite cobalt vanadium nitride nanowire electrocatalyst and preparation method and application thereof | |
| US9099752B2 (en) | Electrocatalyst for electrochemical conversion of carbon dioxide | |
| US11534739B2 (en) | Lignite char supported nano-cobalt composite catalyst and preparation method thereof | |
| CN106179440A (en) | N doping multi-stage porous charcoal and its preparation method and application | |
| CN109346732B (en) | Nitrogen-doped porous carbon catalyst prepared from potatoes and preparation and application thereof | |
| CN112844476A (en) | Biomass-based carbon material loaded nano nickel catalyst and preparation method and application thereof | |
| CN110436459A (en) | A kind of preparation method being graphitized graded porous carbon | |
| CN108623436B (en) | Method for converting cellulose into bioethanol by one-pot method | |
| CN111785980A (en) | Biomass-based catalyst for direct formic acid fuel cell anode and preparation method thereof | |
| CN106179471A (en) | Spherical hollow catalyst of hydrogen production by ethanol steam reforming and preparation method thereof | |
| CN114023980A (en) | Preparation method of nitrogen-doped porous carbon material based on furfural residues and electrocatalytic oxygen reduction performance of nitrogen-doped porous carbon material | |
| CN114433163A (en) | In-situ modified and pore-controllable biochar-supported ruthenium catalyst, preparation method thereof and application thereof in lignin | |
| CN111135848B (en) | Wood-based carbon catalyst, preparation method thereof and method for preparing cyclohexanone by phenol hydrogenation | |
| KR101742530B1 (en) | Catalyst for oxydizing electrode in water electrolyzing device and method of preparing the same | |
| CN115350721B (en) | Nickel-based double-active-domain catalyst and preparation method and application thereof | |
| CN115888847A (en) | Carbon-nitrogen material, preparation method and application thereof, and supported catalyst and application thereof | |
| CN115041230B (en) | Metal-supported nickel-manganese spinel nanosphere aerogel and preparation method and application thereof | |
| CN112237946A (en) | Terephthalic acid hydrofining reaction and catalyst thereof | |
| CN110329992A (en) | Low-temperature methanol steam reforming catalyst for preparing hydrogen and preparation method thereof | |
| CN112275282B (en) | Preparation method and application of Pt nanoparticle-loaded biochar catalyst | |
| CN108855209B (en) | Copper-zinc alloy supported hierarchical porous titanium silicalite molecular sieve catalytic material and preparation method thereof | |
| CN113546631A (en) | La modified Ni/Al2O3Catalyst, preparation method and application | |
| CN113751007A (en) | Catalyst of carbon-coated nickel oxide and preparation method and application thereof | |
| CN113750991A (en) | Catalyst of carbon-coated nickel oxide and preparation method and application thereof | |
| CN113385176B (en) | Hydrogenation saturation catalyst and preparation method and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |