WO2021121088A1 - Mesoporous carbon material loaded cobalt-based catalyst and preparation method therefor - Google Patents

Abstract

The present invention relates to the technical field of metal catalysts, and provides a mesoporous carbon material loaded cobalt-based catalyst and a preparation method therefor. The preparation method for the cobalt-based catalyst comprises: (1) dissolving Co(NO 3) 2•6H 2O into an absolute ethanol solution; (2) soaking a mesoporous carbon material GMC into the solution in step (1), and then evaporating same in a rotary evaporator to obtain a mixture; and (3) placing the mixture in step (2) into an oven for drying, and then calcining same to obtain the catalyst. The catalyst is higher in graphitization degree, more uniform in CoO particle dispersion, higher in CO conversion rate, lower in CO 2 generation rate, and better in C 5+ selectivity.

Description

Cobalt-based catalyst supported by mesoporous carbon material and preparation method thereof Technical field

The invention relates to a cobalt-based catalyst supported by a mesoporous carbon material and a preparation method thereof, and belongs to the technical field of metal catalysts.

Background technique

Since the industrial revolution, human demand for energy has continued to increase, and the limitation of non-renewable resources such as oil and coal has forced people to seek new energy sources, such as nuclear energy, wind energy, and solar energy, which are hot topics of research and discussion. Among them, biomass is one of the core topics. It has the advantages of wide sources, wide variety, and great development potential. People use biomass to convert it into fuel, electricity, etc., not only to solve the energy problem, but also to reuse some waste biomass.

Porous carbon materials not only have the advantages of carbon materials such as acid and alkali resistance, high temperature resistance, stable chemical properties, and low cost, but also have excellent properties such as regular pore structure, large specific surface area, and adjustable pore size.

At present, the use of hard template method to prepare porous carbon materials has a higher specific surface area, pore volume, and large pore diameter. However, this porous carbon material also has certain limitations in practical applications, such as: the prepared material replicates the template The structure cannot be changed arbitrarily.

In the Fischer-Tropsch catalytic reaction, the choice of carrier is closely related to the catalytic performance of the catalyst. If the interaction between the support and the metal is too strong, it will affect the dispersibility of the metal and is not conducive to the reduction of the metal; on the contrary, it will reduce the stability of the metal.

At present, the active phase of the cobalt-based catalyst for the Fischer-Tropsch reaction is elemental cobalt. Obtaining highly dispersed and highly reduced elemental cobalt particles on the surface of the catalyst is the key to improving the reaction efficiency of the cobalt-based catalyst. In order to improve the dispersion of cobalt species, many research works have used carriers with high specific surface and well-developed pores, such as TiO ₂ , Al ₂ O ₃ , and SiO ₂ to support active components. However, this type of carrier and active components are prone to form difficult-to-reducible species, which makes it difficult to obtain a unified active phase with high dispersion and high reduction on the surface of the catalyst.

Summary of the invention

In order to solve at least one of the above-mentioned problems, the present invention provides a cobalt-based catalyst supported by mesoporous carbon materials and a preparation method thereof. The catalyst of the present invention has a higher CO conversion rate and better catalytic reaction performance; the C ⁵⁺ selectivity is significantly improved.

The first object of the present invention is to provide a method for preparing mesoporous carbon material, the specific steps are:

S1: Use solid-liquid ball mill template method to mix SBA-15 and soybean oil evenly;

S2: Transfer the mixture of S1 into a quartz tube furnace and heat up to 700-900°C for carbonization;

S3: The mixture of S2 is etched with NaOH solution to obtain the mesoporous carbon material, which is marked as mesoporous carbon material GMC.

In one embodiment, the mass ratio of SBA-15 and soybean oil mixture described in S1 is 1:2.

In one embodiment, the mixing method described in S1 is: ball milling with a ball mill at a ^{speed of 400 rpm·min -1} for 5 hours.

In one embodiment, the carbonization process described in S2 is specifically: under the _{protection of N 2} , the heating rate is 4° C.·min ^-1 , and the carbonization time is 5 h.

In one embodiment, the concentration of the NaOH solution described in S3 is 2 mol/L.

In one embodiment, the number of etchings described in S3 is 3 times, and each etching time is 24 hours.

In one embodiment, the preparation method of SBA-15 are as follows: First, 3.0g of surfactant P123 3.0g of glycerin and after mixing, was added to a dilute hydrochloric acid solution 115.0mL (1.5mol.L ^{- 1} ) Then stir in a 37°C water bath for transparency. After 3 hours, stir vigorously and add 6.45g diethyl orthosilicate (TEOS) dropwise. After the addition, stir vigorously for 5 minutes; then put the mixture in a 37°C water bath Let stand for 24 hours, take out the mixture and put it in an oven at 110°C for 12 hours; after cooling to room temperature, the white solid obtained is repeatedly suction filtered and washed to pH=7, and then washed with absolute ethanol for 2 to 3 times, and then the product is placed After being dried in an oven at 80°C, it was put into a muffle furnace and fired at 550°C for 5 hours (heating rate 3°C·min ^-1 ), and finally an ordered mesoporous material SBA-15 was prepared.

The second object of the present invention is to provide a mesoporous carbon material GMC obtained by the preparation method of the present invention.

The third object of the present invention is to provide a cobalt-based catalyst containing the mesoporous carbon material GMC supported by the present invention.

The fourth object of the present invention is to provide a method for preparing the mesoporous carbon material GMC-supported cobalt-based catalyst of the present invention, which includes the following steps:

(1) _{Dissolve Co(NO 3} ) ₂ ·6H ₂ O in anhydrous ethanol solution;

(2) Immerse the mesoporous carbon material GMC in the solution of step (1), and then evaporate in a rotary evaporator to obtain a mixture;

(3) Put the mixture of step (2) into an oven to dry; then calcinate, and then the catalyst can be obtained.

In one embodiment, the _{mass ratio of the Co(NO 3} ) ₂ ·6H ₂ O described in step (1) and the mesoporous carbon material described in step (2) is 1.08:1.

_{In one embodiment, the mass ratio of Co(NO 3} ) ₂ ·6H ₂ O and absolute ethanol mentioned in step (1) is 1:5-50.

In one embodiment, the immersion time in step (2) is 1-2 min.

In one embodiment, the temperature of the rotary evaporator described in step (2) is 35° C., and the evaporation time is 5-40 min.

In one embodiment, the drying temperature in step (3) is 50°C for 2-7 hours.

In one embodiment, the calcination described in step (3) is specifically: _{calcination at 350° C. in an N 2} atmosphere, a heating rate of 3° C.·min ^-1 , and a calcination time of 2-10 h.

The fifth objective of the present invention is the application of the mesoporous carbon material GMC of the present invention in the fields of catalysis, electrochemistry, environment or magnetocatalysis.

The sixth object of the present invention is the application of the catalyst of the present invention in industrial hydrogen production.

The beneficial effects of the present invention:

(1) In the present invention, biomass (soybean oil) is used as a carbon source to prepare a mesoporous carbon material GMC-supported cobalt-based catalyst through a simple one-step solid-liquid ball milling method, and the preparation method is simple and environmentally friendly.

(2) The graphitized mesoporous carbon material GMC prepared by the present invention has a regular and orderly mesoporous structure, relatively large pore volume and specific surface area, and relatively concentrated pore size distribution.

(3) The Co/GMC catalyst of the present invention has a higher degree of graphitization, a more uniform dispersion of CoO particles, a higher CO conversion rate and a lower CO ₂ generation rate, and the C ⁵⁺ selectivity is better, showing Co/GMC is used for Fischer-Tropsch synthesis catalyst with good performance.

Description of the drawings

FIG. 1 is the X-ray diffraction spectrum of the catalyst calcined with carbon support at different temperatures in Example 1. FIG.

Fig. 2 shows the Raman spectra of the catalysts calcined with carbon supports at different temperatures in Example 1.

Fig. 3 is a transmission electron microscope photograph of the catalyst calcined on a carbon support at different temperatures in Example 1, (a) Co/GMC-700, (b) Co/GMC-800, and (c) Co/GMC-900.

4 shows the nitrogen adsorption and desorption curves of the catalyst calcined with carbon support at different temperatures in Example 1. FIG.

Figure 5 is the pore size distribution curve of the catalyst calcined with carbon support at different temperatures in Example 1

_{Fig. 6 shows the H 2} -TPR patterns of the catalyst calcined with a carbon support at different temperatures in Example 1.

Fig. 7 shows the change in CO conversion rate of the catalyst calcined with carbon support at different temperatures in Example 1 during the Fischer-Tropsch synthesis reaction.

FIG. 8 shows the XRD after the Fischer-Tropsch synthesis reaction of the catalyst calcined with carbon support at different temperatures in Example 1. FIG.

Fig. 9 is a transmission electron microscope photograph of the catalyst Fischer-Tropsch synthesis reaction of the carbon support calcined at different temperatures in Example 1, (a) is Co/GMC-700, (b) is Co/GMC-800, (c) Co/ GMC-900.

FIG. 10 is a pore size distribution diagram of GMC-800 of Example 1 and CMK-3 and AC of Comparative Example 1. FIG.

Fig. 11 is a TEM image of GMC-800 of Example 1 and CMK-3 of Comparative Example 1, (a) is GMC-800, and (b) is CMK-3.

Figure 12 shows the nitrogen physical adsorption and desorption curves of GMC-800 of Example 1 and CMK-3 and AC of Comparative Example 1.

Fig. 13 shows the physical adsorption and desorption isotherms of nitrogen after Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC carbon supports of Comparative Example 1 loaded with cobalt.

FIG. 14 is an XRD pattern of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1. FIG.

Figure 15 shows the Raman spectra of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1.

Figure 16 is a transmission electron micrograph of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1; (a) is Co/GMC-800, (b) is Co/CMK- 3. (c) is Co/AC.

_{FIG. 17 shows the H 2} -TPR patterns of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1. FIG.

Figure 18 shows the changes in the CO conversion rate of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1 during the Fischer-Tropsch synthesis reaction.

FIG. 19 shows the XRD after the Fischer-Tropsch synthesis reaction of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1. FIG.

20 is a transmission electron microscope photograph of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1 after the Fischer-Tropsch synthesis reaction.

Detailed ways

The preferred embodiments of the present invention are described below, and it should be understood that the embodiments are for better explaining the present invention and are not used to limit the present invention.

X-ray powder diffraction: XRD can effectively determine the structure of the measured substance. Because different materials have different structural properties, the lattice spacing and diffraction characteristic peak intensity of the measured material can be compared with the standard PDF card to determine the phase composition of the measured material. In addition, because different substances have different diffraction peak intensities and different positions of diffraction peaks, it can be combined with XRD pattern analysis to determine their structural parameter information. Using CuKα as the radiation source, the tube pressure is 40KV, the tube current is 200mA, the scanning range (2θ) is 10°～80°, and the scanning step length is 0.02°. Calculated by the Xie Le formula:

Where D is the grain size; K is the Scherrer constant, β is the half-width of the diffraction peak; λ is the incident X-ray wavelength, and θ is the diffraction angle.

Transmission electron microscope: Use electron beam with a short wavelength as the light source, and then accelerate it to gather and project it on the measured sample. The electrons collide with the atoms in the sample to change the direction, thereby generating three-dimensional scattering, and finally magnifying the impact. On the imaging device. Sample preparation: ultrasonic sample + absolute ethanol mixture, then drip it on the carbon film copper net, and test after drying.

Nitrogen physical adsorption and desorption: Nitrogen adsorption and desorption is a relatively mature and common method to determine the pore size distribution. It can effectively measure the physical structure characteristics of the catalyst such as specific surface area, pore size and pore volume.

Raman spectroscopy: Test instrument: Dilor Labram-1B spectrometer, with He-Ne as the excitation light source, its wavelength is 632.8nm, and the test range is 1mm.

H ₂ temperature-programmed reduction (H ₂ -TPR): Place 0.05g sample in a U-shaped quartz reaction tube, then treat it in a He inert atmosphere at 500°C for 2h, cool to 60°C and switch to 10% H ₂ /Ar mixture, and heat up to 800°C (heating at 10°C·min ^-1 ), and finally detect its hydrogen consumption.

Catalyst performance evaluation: The Fischer-Tropsch operation process is as follows: a certain amount of catalyst is placed in the middle of the stainless steel reaction tube, the reducing gas is turned on and a certain pressure is adjusted for reduction, and the temperature is adjusted to 450°C. After the reduction reaction was carried out for 16 hours, the reducing gas was turned off and the reaction furnace was quickly lowered to room temperature. Turn on the gas chromatography GC-9160 and GC-2060, and operate according to the operating procedures. Turn on the synthesis gas and adjust it to a constant flow rate, then heat the reaction furnace to a certain temperature, take samples every 5 hours, stop sampling for 60 hours after the reaction, and turn off the synthesis gas and gas chromatograph. The reaction product can be analyzed and detected by gas chromatography: GC-9160 gas chromatograph detection: FID is used to detect C ₁ -C ₃₀ reaction products; unreacted synthesis gas and short-chain hydrocarbons can be detected by GC-2060 gas chromatograph : Use FID to detect CH ₄ , C ₂ H ₆ , C ₃ H ₈ and C ₄ H ₁₀ ; Use TCD to detect H ₂ , N ₂ , CO, CH ₄ and CO ₂ .

The specific performance evaluation is as follows:

1) Calculate the conversion rate of CO based on the carbon balance (using N ₂ as the internal standard):

(2) In the formula, _{Sinitial N2} , _{Sfinal N2} , _{Sinitial CO} and _{Sfinal CO} are respectively expressed as _{the peak areas of initial N 2} , final N ₂ , initial CO and final CO in the TCD chromatogram.

2) The amount of _{CH 4 product:}

_{Based on the peak areas of N 2} and CH ₄ after separation on the TDX-01 column, the amount _{of CH 4} produced in the reaction can be calculated.

In the formula (3), S _CH4 , S _N2 , and f _CH4 , f _N2 are respectively expressed as the corresponding _{area peaks of CH 4} and N ₂ in the TCD chromatogram and their internal standard factors.

3) The selectivity of _{C n products:}

The amount of various hydrocarbon product substances in the reaction product (expressed in terms of the amount of carbon atom-containing substances) in the reaction product is obtained by the proportional relationship of all products detected by gas chromatography. Then, with CH ₄ as the second internal standard, the peak area of each hydrocarbon separated by FID is used to obtain the amount of each component in the product:

The hydrocarbon product selectivity is calculated by formula (5)

Example 1

A method for preparing a cobalt-based catalyst supported by mesoporous carbon material GMC includes the following steps:

(1) Preparation of ordered mesoporous carbon material (GMC):

Using the solid-liquid ball mill template method, the mixture of SBA-15 and soybean oil (mass ratio 1:2) was ball milled at 400 rpm·min ^-1 for 5 hours with a ball mill, then mixed uniformly, then the mixture was divided into three parts, and then transferred into In the quartz tube furnace, under the _{protection of N 2} , the temperature was raised to 700, 800 and 900 ℃ for carbonization for 5 hours at 4℃·min ^{-1 to produce three kinds of materials calcined at different temperatures.} Use NaOH solution (concentration 2mol/L) to etch 3 times, each etching time is 24h, in order to remove the hard template SBA-15, and finally obtain porous materials calcined at different temperatures, marked as GMC-700, GMC -800, GMC-900.

(2) Preparation of GMC-700, GMC-800, GMC-900 catalysts by impregnation method:

Take 0.8719g Co(NO ₃ ) ₂ ·6H ₂ O and dissolve it in excess absolute ethanol solution, and then immerse 0.8g porous carbon materials (GMC-700, GMC-800, GMC-900) into excess cobalt nitrate ethanol solution , And then slowly evaporate in a rotary evaporator at 35°C, and then put the sample in an oven at 50°C to dry. Finally, the catalyst was calcined at 350°C under _{N 2} ^{atmosphere (heating at 3°C·min -1} ), and finally three catalysts Co/GMC-700, Co/GMC-800, and Co/GMC-900 were obtained.

Comparative Example 1: The carbon material in Example 1 was replaced with mesoporous carbon CMK-3 and activated carbon AC

(1) Synthesis and preparation of ordered mesoporous carbon CMK-3:

Take 9g of SBA-15 and 45mL of sucrose concentrated sulfuric acid mixture (mass ratio of 9:1) and mix them thoroughly, and then bake them at 110°C and 160°C for 6 hours. After drying, the obtained solid was mixed with 45 mL of sucrose concentrated sulfuric acid mixture (mass ratio of 9:1), and then baked at 110°C and 160°C for 6 hours. Then, _{under the protection of N 2} , the temperature is raised to 900 ℃ for carbonization for 5 hours at 4 ℃·min ^-1 , then the carbonized sample is fully treated with 2mol/L NaOH solution, filtered and washed with deionized water for 2 to 3 times, and finally at 100 ℃ drying.

(2) Preparation of catalyst:

Take 0.8719g of Co(NO ₃ ) ₂ ·6H ₂ O and dissolve it in an excess of absolute ethanol solution, then immerse 0.8g of carbon materials (mesoporous carbon CMK-3, activated carbon AC) into the excess ethanol solution of cobalt nitrate, and then Slowly evaporate in a rotary evaporator at 35°C, and then put the sample in an oven at 50°C to dry. Finally, the catalyst _{was calcined at 350°C under N 2} atmosphere (increased at 3°C·min ^-1 ), and finally two catalysts, Co/CMK-3 and Co/AC, were obtained respectively.

The catalysts of Example 1 and Comparative Example 1 were tested for performance, and the specific test results are as follows:

FIG. 1 is the X-ray diffraction spectrum of the catalyst calcined with carbon support at different temperatures in Example 1. FIG. It can be seen from Figure 1 that the diffraction peak at 26.6° corresponds to the characteristic diffraction peak of graphitized carbon. Compared with the XRD diffraction peaks of the cobalt-based catalyst supported after the carbon support is calcined at different temperatures, it can be seen that the mesopores with high calcining temperature Carbon materials have a high degree of graphitization. The diffraction peaks at 36.4°, 42.3°, 61.6°, 73.9° and 77.8° belong to the characteristic diffraction peaks of different crystal planes of CoO (JCPDS 43-1004) on the catalyst surface. Only CoO is present on the surface of the support, and no other cobalt oxides are present. In addition, the intensities of the CoO peaks formed on the mesoporous carbon cobalt-based catalysts calcined at different temperatures are different, indicating that the size of the CoO particles is also different, indicating that the structure of the carbon support itself, such as the degree of graphitization, porosity, etc. The impact. The average particle size of CoO in the carbon-supported cobalt-based catalysts calcined at 700, 800, and 900°C was calculated by the Scherer formula to be 10.1, 11.6, and 8.1 nm, respectively.

Fig. 2 shows the Raman spectra of the catalysts calcined with carbon supports at different temperatures in Example 1. It can be seen from the figure that there are two scattering intensity peaks. The former is caused by single crystal graphite defects and is called D peak, and the latter is caused by ^{the in-plane stretching vibration of carbon atom sp 2} hybridization, which is called G peak. . Under normal circumstances, the ratio of the area of the D peak to the G peak determines the degree of graphitization of the carbon material. The _{smaller the ratio of I D} /I _G (the area ratio of the two peaks), the degree of graphitization of the prepared carbon material. Higher. _{The I D} /I _G ratios of Co/GMC-700, Co/GMC-800 and Co/GMC-900 are 1.879, 1.744 and 1.550, respectively. Therefore, the graphite of Co/GMC-900 catalyst calcined at 900℃ The degree of chemistry is higher. In addition, the increase in the calcination temperature of the carrier causes the peak to move in the direction of the short wave number, that is, a red shift occurs, which is caused by graphitization defects.

Fig. 3 is a transmission electron microscope photograph of the catalyst calcined on a carbon support at different temperatures in Example 1, (a) Co/GMC-700, (b) Co/GMC-800, and (c) Co/GMC-900. It can be seen from the figure that the cobalt metal particles are uniformly dispersed on the surface of the mesoporous carbon support and the inner surface of the pores. As the calcining temperature of the carbon material increases, the mesoporous structure of the carbon is destroyed. In addition, the particle size distribution diagram obtained by TEM shows that the particle sizes of CoO in Co/GMC-700, Co/GMC-800, and Co/GMC-900 are 10.5~15.5nm, 9~12nm and 7~9nm, respectively. This is basically consistent with the particle size obtained by XRD.

4 shows the nitrogen adsorption and desorption curves of the catalyst calcined with carbon support at different temperatures in Example 1. FIG. It can be seen from the figure that these three different catalysts _{have a hysteresis loop between the relative pressure P/P 0} =0.4～1, indicating that the adsorption-desorption curve belongs to the IV type isotherm adsorption curve and has a mesoporous structure. Moreover, the hysteresis ring of the carbon support with higher calcination temperature is larger, which may be due to the larger pore volume. At the starting point B of the hysteresis loop, capillary condensation begins to appear in the smallest hole. As the relative pressure P/P ₀ gradually increased, capillary condensation gradually appeared in the mesopores until the pressure was saturated. The entire system was filled with condensation liquid, and a larger hysteresis loop appeared.

Fig. 5 is a pore size distribution curve of a catalyst calcined with a carbon support at different temperatures in Example 1. It can be seen from the figure that the pore diameters of the three catalysts Co/GMC-700, Co/GMC-800 and Co/GMC-900 are basically concentrated at 3.9nm.

Table 1 shows the specific surface area, pore diameter and average pore volume data of Co/GMC-700, Co/GMC-800 and Co/GMC-900 in Example 1. It can be seen from the table that the catalysts Co/GMC-700, Co The specific surface areas of /GMC-800 and Co/GMC-900 are 207m ^{2 .g -1} , 246m ^{2 .g -1} , and 306m ² .g ^{-1 respectively} ; the catalysts Co/GMC, Co/GMC-800 and Co/GMC an average pore volume of -900 respectively ^{0.12cm 3 .g -1, 0.22cm 3 .g} -1, 0.26cm 3 .g -1. It can be seen from the above that as the calcination temperature of the carbon support increases, the specific surface area and total volume of the catalyst continue to increase.

Table 1 The specific surface area, pore diameter and average pore volume data of Co/GMC-700, Co/GMC-800 and Co/GMC-900 in Example 1

sample	Specific surface area (m 2 .g -1 )	Aperture (nm)	Average pore size (cm 3 .g -1 )
Co/GMC-700	207	2.29	0.12
Co/GMC-800	246	3.62	0.22
Co/GMC-900	306	3.51	0.26

_{Fig. 6 shows the H 2} -TPR patterns of the catalyst calcined with a carbon support at different temperatures in Example 1. It can be seen from the figure that all catalysts show three reduction peaks of hydrogen. The first reduction peak from left to right represents _{the hydrogen reduction peak of Co 3} O ₄ → CoO, and the second represents the hydrogen reduction peak of CoO → Co. Reduction peak, the third represents the gasification peak of the carbon carrier. In addition, there is no reduction peak above 700°C, indicating that no hard-to-reducible compounds are formed on the surface of the catalyst. The cobalt-based catalyst supported on a carbon support with a higher calcining temperature achieves a _{higher reduction temperature of the Co 3} O ₄ →CoO→Co active phase, indicating that the carbon support calcined at a higher temperature is more conducive to increasing the mesoporous carbon The interaction between the carrier and the cobalt is enhanced. TEM combined with nitrogen physical adsorption and desorption BET analysis showed that the collapse of the mesoporous structure of the mesoporous carbon material introduced more physical defects, improved the dispersibility of cobalt on the mesoporous carbon support, and the reduction of the cobalt particle size increased The interaction force with the carrier improves the stability of the catalyst.

Fig. 7 shows the change in CO conversion rate of the catalyst calcined with carbon support at different temperatures in Example 1 during the Fischer-Tropsch synthesis reaction. It can be seen from the figure that the carbon support calcined at a higher temperature has a higher CO conversion rate. Combining TEM and nitrogen adsorption and desorption BET analysis, it may be due to the increase in temperature that the surface of the mesoporous carbon support produces more physical Defects, and fully opened the mesopores, and increased the surface area of the carbon support. The specific surface area of Co/GMC-800 has a smaller growth relative to Co/GMC-700 and the particle size of Co/GMC-800 is larger. The CO conversion rate of the Co/GMC-800 catalyst calcined at 800℃ is relatively low. After 60 hours of catalyst performance evaluation of Co/GMC-700, Co/GMC-800 and Co/GMC-900, the CO conversion rate decreased from 45%, 37% and 55% to 35%, 26% and 42% respectively .

Table 2 shows the Fischer-Tropsch synthesis catalytic reaction performance of the Co/GMC-700, Co/GMC-800 and Co/GMC-900 catalysts in Example 1. It can be seen from the table that the C ^{5+ of} Co/GMC-900 has Higher selectivity, which may be due to its strong graphitization degree and graphite defects promote the electron transfer ability between the metal cobalt and CO, and then activate the CO molecules, so that the adsorbed CO molecules on the catalyst surface increase, which is beneficial to the formation of C _{5 +} A mixture of the above.

Table 2 Fischer-Tropsch synthesis catalytic reaction performance of Co/GMC-700, Co/GMC-800 and Co/GMC-900 catalysts in Example 1

^a Reaction conditions: T=270℃, P=2MPa, H _{2 /} CO=2, GHSV=3.6L·h ^-1 g ^-1

^b Except for carbon dioxide, the selectivity of hydrocarbons has been standardized.

^c C ₌ /C _n is the molar ratio of C _2-4 olefin to paraffin.

FIG. 8 shows the XRD after the Fischer-Tropsch synthesis reaction of the catalyst calcined with carbon support at different temperatures in Example 1. FIG. It can be seen from the figure that the 2θ values of the three obvious diffraction peaks of Co/GMC-700, Co/GMC-800 and Co/GMC-900 are 42.5°, 45.7° and 68.3°, corresponding to Co ₂ C(JCPDS 72-1369), while the other diffraction peaks of Co ₃ C (JCPDS 89-2866) correspond to 60° of Co/GMC-700, 60° and 75° of Co/GMC-800, and Co/GMC-800. 60°, 75° and 83° of GMC-800. In addition, after the reaction, the catalysts Co/GMC-700, Co/GMC-800 and Co/GMC-900 all have graphitization peaks at 2θ=26.1°, but Co/GMC-900 has the highest graphitization peak.

Fig. 9 is a transmission electron microscope photograph of the catalyst Fischer-Tropsch synthesis reaction of the carbon support calcined at different temperatures in Example 1, (a) is Co/GMC-700, (b) is Co/GMC-800, (c) Co/ GMC-900. It can be seen from the figure that as the reaction time changes, the particle size of CoO particles continues to increase and agglomeration occurs; the particle sizes of CoO particles are 10.5-14nm, 12.5-17.5nm and 10-14nm, respectively.

FIG. 10 is a pore size distribution diagram of GMC-800 of Example 1 and CMK-3 and AC of Comparative Example 1. FIG. It can be seen from the figure that the pore size distributions of GMC-800, CMK-3 and AC are mainly concentrated in 3.6nm, 3.9nm and 3.9nm, which shows that the carbon materials prepared with SBA-15 as the hard template have orderly Mesoporous structure.

Fig. 11 is a TEM image of GMC-800 of Example 1 and CMK-3 of Comparative Example 1, (a) is GMC-800, and (b) is CMK-3. It can be seen from the figure that the prepared GMC-800 and CMK-3 have an ordered structure.

Figure 12 shows the nitrogen physical adsorption and desorption curves of GMC-800 of Example 1 and CMK-3 and AC of Comparative Example 1. It can be seen from the figure that _{there is a strong absorption peak in the low zone P/P 0} (0～0.4), which is the characteristic of micropores; when the relative pressure P/P ₀ ＝0.4～1, GMC-800 Both CMK-3 and CMK-3 have a hysteresis loop, which shows that their adsorption and desorption curves are typical class IV curves with typical mesoporous structure. The absorption and desorption curve of AC is an I-type isotherm, which is a microporous structure. As shown in the figure, the N ₂ adsorption and desorption isotherm of the catalyst is similar to its corresponding support adsorption and desorption isotherm, which indicates that the structure and performance of the catalyst support change little during the preparation process.

Fig. 13 shows the nitrogen physical adsorption and desorption isotherms of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC carbon supports of Comparative Example 1 loaded with cobalt. It can be seen from the figure that the specific surface area, pore size and pore volume of CMK-3 are the largest among the three carbon support materials, which are respectively 939 m ^{2 .g -1} , 1.31 cm ^{3. G -1} and 5.57 nm. The specific surface area of AC and CMK-3 is higher than that of GMC-800. Comparing the average pore diameter of the carrier, the average pore diameter of CMK-3 is the largest (5.57nm), AC is the smallest (2.25nm), and GMC-800 is in the middle (5.57nm). In addition, after 15wt.% cobalt is loaded on the corresponding carbon support, the specific surface area and pore volume of the support significantly decrease. It may be due to the cobalt oxide particles filling the pores on the surface of the carrier.

Table 3 shows the physical and chemical properties of the carbon material GMC-800 in Example 1 and the CMK-3 and AC in Comparative Example 1 before and after loading cobalt. It can be seen from the table that the specific surface area, pore size and pore volume of CMK-3 are the largest among the three carbon support materials, which are respectively 939m ^{2 .g -1} , 1.31cm ^{3 .g -1} and 5.57nm. The specific surface area of AC and CMK-3 is higher than that of GMC-800. Comparing the average pore diameter of the carrier, the average pore diameter of CMK-3 is the largest (5.57nm), AC is the smallest (2.25nm), and GMC-800 is in the middle (5.57nm). In addition, after 15wt.% cobalt is loaded on the corresponding carbon support, the specific surface area and pore volume of the support significantly decrease.

Table 3 shows the physical and chemical properties of carbon material GMC-800 in Example 1 and CMK-3 and AC in Comparative Example 1 before and after loading cobalt

sample	Specific surface area (m 2 .g -1 )	Aperture (nm)	Average pore size (cm 3 .g -1 )
GMC	442	5.24	0.58
CMK-3	939	5.57	1.31
AC	657	2.25	0.37
Co/GMC-800	246	3.62	0.22
Co/CMK-3	709	4.30	0.76
Co/AC	492	2.44	0.30

14 is an XRD pattern of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1. FIG. It can be seen from the figure that the small-angle X-ray diffraction pattern of the mesoporous material mainly has diffraction peaks at 1 to 2, while the prepared catalysts Co/GMC-800 and Co/CMK-3 have diffraction peaks at 1.039. It shows that they have a mesoporous structure. In addition, it can be seen from the figure that the diffraction peak at 2θ=26.6° corresponds to the characteristic diffraction peak of graphitized carbon, which shows that the degree of graphitization of the porous carbon material GMC is much higher than that of CMK-3 and AC. The diffraction peaks at 2θ=36.4°, 42.3°, 61.6°, 73.9° and 77.8° indicate that the cobalt nanoparticles in the catalyst mainly exist in the form of CoO (JCPDS 43-1004). Comparing the CoO characteristic diffraction peak intensity of different catalysts in the figure, it is found that the CoO peak intensity of the catalyst Co/AC is stronger than that of the catalysts Co/GMC-800 and Co/CMK-3, indicating that the CoO particles on the catalyst Co/AC are larger. The average particle size of Co/GMC-800, Co/CMK-3 and Co/AC catalysts CoO calculated by Scherrer equation are 11.6nm, 6.9nm and 19.2nm, respectively.

Figure 15 shows the Raman spectra of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1. It can be seen from the figure that there are two scattering intensity peaks on the Raman spectrum. The former is caused by single-crystal graphite defects, called D peaks, and the latter is caused by the in-plane stretching vibration of the ^{sp 2 hybridization of carbon atoms.} , Is called G peak. Under normal circumstances, the ratio of the area of the D peak to the G peak determines the degree of graphitization of the carbon material. The _{smaller the ratio of I D} /I _G (the area ratio of the two peaks), the degree of graphitization of the prepared carbon material. Higher. _{It can be seen from Figure 3.6 that the I D} /I _G ratios of Co/GMC-800, Co/CMK-3, and Co/AC are 1.94, 1.98, and 2.65, respectively, which shows that Co/GMC-800 and Co/CMK -3 has a relatively high degree of graphitization.

Figure 16 is a transmission electron micrograph of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1; (a) is Co/GMC-800, (b) is Co/CMK- 3. (c) is Co/AC. It can be seen from the figure that the catalysts Co/GMC-800 and Co/CMK-3 have a mesoporous structure. CoO particles are uniformly dispersed on the mesoporous carbon material GMC, and its structure is relatively regular; while the mesoporous carbon material CMK-3 is loaded with cobalt, its ordered mesoporous structure partially collapses, but the CoO nanoparticles can be uniformly dispersed in CMK-3 On the carrier. For Co/AC, CoO is relatively concentrated. In addition, the particle size distribution diagram obtained by TEM shows that the particle sizes of CoO in Co/GMC-800, Co/CMK-3, and Co/AC are 9-12nm, 6.5-8nm and 12-17.5nm, respectively.

_{FIG. 17 shows the H 2} -TPR patterns of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1. FIG. It can be seen from the figure that all catalysts show three reduction peaks of hydrogen. The first reduction peak from left to right represents _{the hydrogen reduction peak of Co 3} O ₄ → CoO, and the second reduction peak represents the reduction peak of CoO → Co. The hydrogen reduction peak, the third reduction peak represents the gasification peak of the carbon carrier. There is no reduction peak above 700℃, indicating that no hard-to-reducible compounds are formed on the surface of the catalyst. This also shows that the interaction force between cobalt oxide and carbon support is better than that of oxide support (for example: SiO ₂ and Al ₂ O ₃ The interaction force between) and the cobalt catalyst is much weaker.

Figure 18 shows the changes in the CO conversion rate of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1 during the Fischer-Tropsch synthesis reaction. It can be seen from the figure that the stability of the three catalysts is different due to the influence of the structural properties of the support. The catalytic activity of the catalyst Co/CMK-3 is relatively stable. After the catalytic reaction is carried out for 60 hours, the CO conversion rate has dropped from 21% by 15%, while the CO conversion rate of Co/GMC has dropped from 37% to 26%. The CO conversion rate of Co/AC The conversion rate decreased by 9% from 19%.

Table 4 shows the Fischer-Tropsch synthesis catalytic reaction performance of the Co/GMC-800 of Example 1 and the Co/CMK-3 and Co/AC catalysts of Comparative Example 1. It can be seen from the table that Co/GMC-800 has a higher Conv. _CO (29.4%), which may be due to the higher degree of graphitization of GMC-800, which facilitates the transfer of electrons between cobalt and CO and promotes CO activation. Although the Co/CMK-3 catalyst has a larger specific surface area and pore volume, the Conv. _{CO is} only 18.05%, which may be due to the amorphous and poor graphitized structure of CMK-3 after cobalt loading. Caused by the destruction of part of the orderly structure. In addition, it can be seen from the table that high C ⁵⁺ selectivity is often accompanied by low CH ₄ and C ₂ -C ₄ selectivity. The catalyst Co/GMC-800 is compared with the catalyst Co/CMK-3 and Co/ AC can obtain more C ⁵⁺ hydrocarbon products and lower methane and C ₂ -C ₄ . This may be due to the strong graphitization degree which promotes the electron transfer ability between the metal cobalt and CO, and then activates the CO molecules, which makes the CO molecules adsorbed on the catalyst surface increase, which is conducive to the formation of a mixture of ^{C 5+ and above.}

Table 4 Fischer-Tropsch synthesis catalytic reaction performance of Co/GMC-800 in Example 1 and Co/CMK-3 and Co/AC catalysts in Comparative Example 1

^a Reaction conditions: T=270℃, P=2MPa, H _{2 /} CO=2, GHSV=3.6L·h ^-1 g ^-1

^b Except for carbon dioxide, the selectivity of hydrocarbons has been standardized.

^c C ₌ /C _n is the molar ratio of C _2-4 olefin to paraffin.

FIG. 19 shows the XRD after the Fischer-Tropsch synthesis reaction of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1. FIG. It can be seen from the figure that the 2θ values of the three obvious diffraction peaks of Co/GMC and Co/CMK-3 are 42.5°, 45.7° and 68.3°, which correspond to the _{characteristic diffraction peaks of Co 2} C (JCPDS 72-1369). The other two diffraction peaks correspond to Co ₃ C (JCPDS89-2866), and their 2θ values are 60° and 75°. This shows that new species appear in the catalyst after the reaction, which is also a main reason for the decrease of carbon monoxide over time in the reaction process. In addition, the graphitization diffraction peaks of the catalysts Co/GMC and Co/CMK-3 at 2θ=26.1° were significantly enhanced after the reaction.

20 is a transmission electron microscope photograph of Co/GMC-800 of Example 1 and Co/CMK-3 and Co/AC of Comparative Example 1 after the Fischer-Tropsch synthesis reaction. It can be seen from the figure that as the reaction time changes, the particle size of CoO particles increases continuously and agglomerates. The particle size distribution diagram obtained by TEM shows that the particle sizes of CoO in Co/GMC-800, Co/CMK-3, and Co/AC are 12.5 to 17.5 nm, 12 to 17 nm and 15 to 25 nm, respectively. This also confirmed the reason why the CO conversion rate of the catalyst decreased rapidly after doping with nitrogen.

Although the present invention has been disclosed as above in preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention should be defined by the claims.

Claims (10)

1. A preparation method of mesoporous carbon material, characterized in that it comprises the following steps:

   S1: Use solid-liquid ball mill template method to mix SBA-15 and soybean oil evenly;

   S2: Transfer the mixture of S1 into a quartz tube furnace and heat up to 700-900°C for carbonization;

   S3: The mixture of S2 is etched with NaOH solution to obtain the mesoporous carbon material.
2. The preparation method according to claim 1, wherein the mass ratio of the SBA-15 and soybean oil mixture of S1 is 1:2.
3. The preparation method according to claim 1, wherein the carbonization process of S2 is specifically: under N ₂ protection, a heating rate of 4° C.·min ^-1 , and a carbonization time of 5 h.
4. The mesoporous carbon material obtained by the preparation method of claim 1.
5. A cobalt-based catalyst comprising the mesoporous carbon material supported by claim 1.
6. The preparation method of the catalyst according to claim 5, characterized in that it comprises the following steps:

   (1) _{Dissolve Co(NO 3} ) ₂ ·6H ₂ O in anhydrous ethanol solution;

   (2) Immerse the mesoporous carbon material in the solution of step (1), and then evaporate in a rotary evaporator to obtain a mixture;

   (3) Put the mixture of step (2) into an oven to dry; then calcinate, and then the catalyst can be obtained.
7. The preparation method according to claim 6, wherein _{the mass ratio of Co(NO 3} ) ₂ ·6H ₂ O and absolute ethanol in step (1) is 1:5-50.
8. The preparation method according to claim 6, wherein the calcination in step (3) is specifically: _{calcination at 350°C under N 2} atmosphere, a heating rate of 3°C·min ^-1 , and a calcination time of 2-10h .
9. The application of the mesoporous carbon material of claim 4 in the fields of catalysis, electrochemistry, environment or magnetocatalysis.
10. The application of the cobalt-based catalyst supported by the mesoporous carbon material of claim 5 in industrial hydrogen production.

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