CN105289421B - Equipment and method for preparing methanol by photocatalytic reduction of CO2 using graphene macroscopic materials - Google Patents

Abstract

The invention provides a kind of graphene macro material photocatalytic reduction CO _The equipment for preparing methanol comprises a reaction box, the inner wall of the reaction box is provided with a plurality of ultraviolet lamps, and the reaction box is provided with a container for holding a solution medium A reaction bottle, the bottom of the reaction bottle is provided with a heater for heating the solution medium, the top of the reaction bottle is communicated with a condensation pipe, and the condensation pipe is communicated with a condensate collection tank, and the reaction bottle is The lower part communicates with the _CO gas cylinder located outside the reaction box through the _CO pipeline, the reaction cylinder is provided with a porous partition, the porous partition is provided with catalyst packing, and the _CO pipeline is provided with a flow regulator valve. The invention also provides a method for preparing methanol by using the device to carry out photocatalytic reduction of _CO2 by the graphene macroscopic material. The invention adopts the graphene macroscopic material as the photocatalyst, which has good catalytic effect, high catalytic efficiency and high methanol yield.

Description

Equipment and method for preparing methanol by photocatalytic reduction of CO2 using graphene macroscopic materials

technical field

The invention belongs to the technical field of photocatalysis, and in particular relates to a device and a method for preparing methanol by photocatalytic reduction of _CO2 using a graphene macroscopic material.

Background technique

As a newcomer in the family of carbon materials, graphene has rapidly become a hot spot in scientific research due to its more and more peculiar physical and chemical properties and its extraordinary performance in many application fields. Graphene is considered as the basic structural unit of all ^sp2 hybridized carbonaceous materials, which brings new opportunities for the construction of carbonaceous materials with specific structures and functions. Through structural assembly, graphene sheets can construct functionalized graphene macroscopic materials with specific structures, reflecting the excellent properties of microscopic graphene sheets to macroscopic materials, such as excellent mechanical properties, fast electron mobility, super large The specific surface area and good adsorption capacity make functionalized graphene macroscopic materials show good application prospects in the fields of catalysis, adsorption, energy storage, supercapacitors, and biomedicine.

As a rich potential carbon source, the development and application of CO ₂ transformation and utilization technology is an important research direction for the sustainable development strategy in the world in the future. Among them, the photocatalytic reduction of _CO2 directly converts light energy into chemical energy, which is environmentally friendly and low in consumption, and is conducive to the realization of carbon recycling, and has become one of the most promising technologies for _CO2 conversion and utilization. However, in the existing photocatalytic reaction devices, the catalysts are mostly uniformly mixed in the reaction medium in the form of tiny particles, which makes it difficult to separate the reaction products from the reaction system, and shortens the service life of the catalysts so that they cannot be reused many times. Obviously, this limits the industrialization and application of photocatalytic _CO reduction technology to a certain extent.

Therefore, the development of a photocatalytic reduction of _CO2 to produce methanol using functionalized graphene macro-materials can not only broaden the application of graphene macro-materials, but also solve the problem that the catalyst cannot be reused many times during the photocatalytic reaction. Good economic benefits.

Contents of the invention

The technical problem to be solved by the present invention is to provide a kind of graphene macroscopic material photocatalytic reduction CO ₂ to prepare methanol for the above-mentioned deficiencies in the prior art. The equipment can be used to prepare methanol by photocatalytic reduction of _CO2 with graphene macroscopic materials. The preparation process is green and environmentally friendly, and the operation is simple. The graphene macroscopic materials exhibit excellent photocatalytic performance and high conversion rate of methanol.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a kind of graphene macro material photocatalytic reduction CO _The equipment for preparing methanol is characterized in that it includes a reaction box, and the inner wall of the reaction box is provided with a plurality of ultraviolet rays lamp, the reaction box is provided with a reaction bottle for containing the solution medium, the bottom of the reaction bottle is provided with a heater for heating the solution medium, the upper part of the reaction bottle is connected with a condensation pipe, the The condensation pipe is communicated with the condensate collection tank, and the lower part of the reaction bottle is communicated with the _CO gas cylinder outside the reaction box through the _CO pipeline, and the reaction bottle is provided with a porous partition, and the porous partition is provided with There is a catalyst packing, and a flow regulating valve is set on the _CO2 pipeline.

The above-mentioned graphene macroscopic material photocatalytic reduction CO _The equipment for preparing methanol is characterized in that: the reaction box is a cylindrical structure with both ends closed, the number of the ultraviolet lamps is six, and the six ultraviolet lamps Evenly distributed on the inner wall of the reaction box.

The above-mentioned graphene macro-material photocatalytic reduction of CO _The equipment for preparing methanol is characterized in that: the material of the reaction bottle is quartz glass.

The above-mentioned equipment for preparing methanol by photocatalytic reduction of _CO2 using graphene macroscopic materials is characterized in that: the holes in the porous separator are circular holes, and the diameter of the circular holes is 0.5 mm to 1 mm.

In addition, the present invention also provides a kind of utilizing above-mentioned equipment to carry out graphene macroscopical material photocatalytic reduction CO _The method for preparing methanol is characterized in that, the method comprises the following steps:

Step 1, adopting anthracite as raw material to prepare graphene macroscopic material;

Step 2, using deionized water as a solvent to prepare a NaOH-Na ₂ SO ₃ mixed solution, the concentrations of NaOH and Na ₂ SO ₃ in the NaOH-Na ₂ SO ₃ mixed solution are both 0.05-0.15 mol/L;

Step ₃ , NaOH-Na2SO3 mixed solution described in step ₂ is added in the reaction flask as a solution medium, the graphene macroscopic material described in step 1 is added in the reaction flask as a catalyst filler, and then the solution medium is The temperature is heated to 68°C-72°C, and then CO ₂ is introduced into the reaction bottle with a CO ₂ cylinder, and the flow rate of CO ₂ is adjusted to 50mL/min-150mL/min through the flow regulating valve, and finally the ultraviolet lamp is turned on. Under the condition that the intensity of ultraviolet light is 300 μW/cm ² to 500 μW/cm ² , the photocatalytic reduction of CO ₂ is carried out, and methanol is obtained in the condensate collection tank.

Above-mentioned method is characterized in that, adopting anthracite described in step 1 is that the concrete process of raw material preparation graphene macroscopic material is:

Step 101: Crushing, sieving, and ball milling the anthracite in sequence to obtain ultrafine coal powder with a particle size D ₉₀ ≤ 20 μm, and then placing the ultrafine coal powder in a graphite crucible, in a temperature range of 2400°C to 2600°C Keep warm for 2.5h to 3.5h under the same conditions to obtain graphitized carbon;

Step 102, using the graphitized carbon described in step 101 as a precursor, adopting the modified Hummers method to prepare coal-based graphene oxide;

Step 103, using the coal-based graphene oxide described in step 102 as a raw material, adopting a chemical reduction self-assembly method to prepare a coal-based graphene hydrogel;

Step 104, freeze-drying the coal-based graphene hydrogel described in step 103 at a temperature of -55°C to -15°C for 36h to 48h to obtain an airgel;

Step 105. Under the protection of an inert atmosphere, heat up the airgel described in step 104 to 550°C-850°C at a heating rate of 5°C/min-10°C/min, then perform annealing treatment at a constant temperature for 1h-4h, and then cool naturally A coal-based graphene macroscopic material is obtained.

The above-mentioned method is characterized in that, the specific process of preparing coal-based graphene oxide by using the improved Hummers method described in step 102 is: the concentrated sulfuric acid with graphitized carbon, sodium nitrate, potassium permanganate and mass concentration of 98% is pressed Mass ratio 1:(0.5~1):5:(30~40) After mixing evenly, stir at a temperature of 0°C~20°C for 10min~50min, then raise the temperature to 30°C~40°C and stir for 100min~300min, Then heat up to 90°C to 100°C and stir for 10min to 20min, add deionized water for dilution, then add a hydrogen peroxide solution with a mass concentration of 30% by dropwise, stir well and then carry out pickling, water washing, filtering and drying in sequence treatment to obtain coal-based graphene oxide; the added amount of the deionized water is 40 to 60 times the mass of the graphitized carbon, and the added amount of the hydrogen peroxide solution is equal to the mass of potassium permanganate.

The above-mentioned method is characterized in that, the specific process of preparing coal-based graphene hydrogel by chemical reduction self-assembly method described in step 103 is: adding the coal-based graphene oxide into deionized water and ultrasonically dispersing evenly to obtain coal-based graphene hydrogel. Graphene oxide-based aqueous solution, and then uniformly mix the aqueous solution of coal-based graphene oxide and ethylenediamine to obtain a mixed solution, and then keep the mixed solution at a temperature of 90°C-120°C for 3h-8h, and cool naturally After obtaining the coal-based graphene hydrogel; the concentration of the coal-based graphene oxide aqueous solution is 2g/L～6g/L, and the mass ratio of coal-based graphene oxide and ethylenediamine in the mixed solution is (0.2～ 0.75):1.

The above method is characterized in that the amount of catalyst filler added in step 3 is: 0.5 g to 5 g of catalyst filler is added per liter of solution medium.

Compared with the prior art, the present invention has the following advantages:

1. The present invention uses coal as a raw material and undergoes high-temperature treatment to produce ultra-pure micro-graphitized carbon, and then prepares coal-based graphene oxide. The raw material has a wide range of sources and low cost, which is conducive to large-scale production and can realize clean utilization of coal resources .

2. The photocatalytic reaction equipment designed by the present invention has a novel and unique structure, is scientific and reasonable, and is easy to use and operate. It can realize the effective separation of the catalyst and the reaction medium after the reaction, and achieve the purpose of repeated regeneration and utilization of the catalyst.

3. In the photocatalytic reaction equipment designed by the present invention, the ultraviolet light source adopts an ordinary ultraviolet lamp, which has low cost and long service life. The influence of light intensity on photocatalytic performance can be discussed by adjusting the number of ultraviolet lamps.

4. In the photocatalytic reaction equipment designed by the present invention, the reaction bottle _CO2 air intake mode adopts countercurrent contact from bottom to top, and the partition in the reaction bottle plays a role in uniform distribution of _CO2 gas, which is beneficial to _CO2 Full contact between gas and liquid medium and catalyst.

5. The photocatalytic reaction equipment designed by the present invention is finally equipped with a heater and an air inlet pipe, which can not only carry out the experiment of photocatalytic reduction of _CO2 , but also satisfy the experiment of photocatalytic degradation of pollutants in water, explore temperature, different gas atmospheres or Effect of dissolved oxygen solubility on photocatalytic performance of photocatalytic materials.

6. The present invention uses anthracite as a raw material to prepare graphene macroscopic material, which presents an obvious two-dimensional graphene sheet structure on the microstructure, and these flexible sheets are stacked and staggered during the assembly process to form well-developed mesh pores structure, with a size distribution in the micron to submicron range. This special three-dimensional network pore forms a smooth mass transfer channel inside the graphene macrobody, which can provide a good microenvironment and a fast charge transfer path for photocatalytic reactions.

7. The present invention uses anthracite as a raw material to prepare graphene macroscopic material, which has a developed three-dimensional network pore structure and multi-sheet layered structure, and can absorb a large amount of _CO2 during the reaction process of photocatalytic reduction of _CO2 to prepare methanol, improving The residence time of CO ₂ gas in the reaction system is reduced, which is conducive to the full contact of CO ₂ gas with the catalyst and the reaction medium; secondly, this special mesh structure forms a smooth mass transfer channel inside it, providing a good environment for chemical reactions. The microenvironment and the path for rapid charge transfer; in addition, the incompletely reduced oxygen-containing functional groups and active sites retained on the surface of graphene macroscopic materials are also conducive to improving its photocatalytic performance.

8. The present invention adopts graphene macroscopic material as photocatalyst, which has good catalytic effect, high catalytic efficiency and high yield of methanol.

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the structure schematic diagram of the equipment for preparing methanol by photocatalytic reduction of _CO2 by graphene macroscopic material of the present invention.

FIG. 2 is a partial enlarged view of A in FIG. 1 .

Fig. 3 is a schematic diagram of the distribution state of the ultraviolet lamps on the inner wall of the reaction box according to the present invention.

Fig. 4 is the SEM photo of the graphene macro material (RGO) of Example 2 of the present invention.

Fig. 5 is an XRD pattern of graphitized carbon (TXC) in Example 2 of the present invention.

Fig. 6 is the XRD patterns of coal-based graphene oxide (CGO) and graphene macroscopic material (RGO) in Example 2 of the present invention.

Fig. 7 is an infrared spectrogram of coal-based graphene oxide (CGO) and graphene macroscopic material (RGO) in Example 2 of the present invention.

Fig. 8 is a Raman spectrum of the graphene macroscopic material (RGO) of Example 2 of the present invention.

Fig. 9 is a graph showing the change of methanol yield over time in the photocatalytic reduction of _CO2 by coal-based graphene oxide (CGO) and graphene macroscopic material (RGO) in Example 2 of the present invention.

Explanation of reference signs:

1—reaction box; 2—solution medium; 3—reaction bottle;

4—heater; 5—catalyst packing; 6—ultraviolet lamp;

7—condensation tube; 8—condensate collection tank; 9—CO ₂ pipeline;

10—flow regulating valve; 11—CO ₂ cylinder; 12—porous partition.

detailed description

The device for preparing methanol by photocatalytic reduction of _CO2 using graphene macroscopic material of the present invention is described by Example 1.

Example 1

As shown in Figure 1-2, the graphene macro material photocatalytic reduction _CO of the present invention The equipment for preparing methanol comprises a reaction box 1, and a plurality of ultraviolet lamps 6 are arranged on the inner wall of the reaction box 1, and in the reaction box 1 A reaction bottle 3 for containing the solution medium 2 is provided, the bottom of the reaction bottle 3 is provided with a heater 4 for heating the solution medium 2, and the upper part of the reaction bottle 3 communicates with the condenser tube 7, the Condensation pipe 7 communicates with condensate collecting tank 8, the bottom of said reaction bottle 3 communicates with _CO gas cylinder 11 located outside reaction box 1 through _CO pipeline 9, said reaction bottle 3 is provided with a porous partition 12 , the porous separator 12 is provided with a catalyst packing 5, and the CO ₂ pipeline 9 is provided with a flow regulating valve 10 .

As shown in FIG. 3 , the reaction box 1 is a cylindrical structure with both ends closed, and the number of the ultraviolet lamps 6 is six, and the six ultraviolet lamps 6 are evenly distributed on the inner wall of the reaction box 1 .

In this embodiment, the material of the reaction bottle 3 is quartz glass.

In this embodiment, the holes in the porous separator 12 are circular holes, and the diameter of the circular holes is 0.5 mm˜1 mm.

The present invention utilizes the apparatus described in embodiment 1 to carry out the photocatalytic reduction _CO of graphene macroscopical material The method for preparing methanol is described through embodiment 2-5.

Example 2

In conjunction with Fig. 1 to 3, the present embodiment utilizes the equipment described in embodiment 1 to carry out graphene macro material photocatalytic reduction CO _The method for preparing methanol comprises the following steps:

Step 1, using anthracite as a raw material to prepare graphene macroscopic materials, the specific process is:

Step 101: Crushing, sieving, and ball milling the anthracite in sequence to obtain ultrafine coal powder with a particle size D ₉₀ ≤ 20 μm, and then placing the ultrafine coal powder in a graphite crucible and keeping it warm at a temperature of 2500°C 3h, obtain graphitized carbon;

Step 102, using the graphitized carbon described in step 101 as a precursor, adopting the modified Hummers method to prepare coal-based graphene oxide, the specific process is: graphitized carbon, sodium nitrate, potassium permanganate and 98% mass concentration Concentrated sulfuric acid was mixed evenly at a mass ratio of 1:0.75:5:35, stirred at a temperature of 10°C for 30 minutes, then heated to 35°C and stirred for 120 minutes, then heated to 95°C and stirred for 15 minutes, then diluted with deionized water Finally, adopt the method of dripping to add the hydrogen peroxide solution whose mass concentration is 30%, carry out pickling, water washing, filtration and drying treatment successively after stirring evenly, obtain coal-based graphene oxide; The addition amount of described deionized water is graphitization 50 times of the charcoal quality, the addition of the hydrogen peroxide solution is equal to the quality of potassium permanganate;

Step 103, using the coal-based graphene oxide described in step 102 as a raw material, adopting a chemical reduction self-assembly method to prepare a coal-based graphene hydrogel, the specific process is: adding the coal-based graphene oxide to deionized water for ultrasonic dispersion Uniformly, to obtain a coal-based graphene oxide aqueous solution, and then mix the coal-based graphene oxide aqueous solution with ethylenediamine to obtain a mixed solution, and then keep the mixed solution at a temperature of 100 ° C for 5 hours, and after natural cooling Obtain coal-based graphene hydrogel; the concentration of the coal-based graphene oxide aqueous solution is 4g/L, and the mass ratio of coal-based graphene oxide and ethylenediamine in the mixed solution is 0.5:1;

Step 104, freeze-drying the coal-based graphene hydrogel described in step 103 at a temperature of -20°C for 40 hours to obtain an aerogel;

Step 105. Under the protection of an inert atmosphere, the airgel described in step 104 is heated to 600° C. at a heating rate of 8° C./min, and then annealed at a constant temperature for 3 hours. After natural cooling, a coal-based graphene macroscopic material is obtained;

Step 2, using deionized water as a solvent to prepare NaOH-Na ₂ SO ₃ mixed solution, the concentrations of NaOH and Na ₂ SO ₃ in the NaOH-Na ₂ SO ₃ mixed solution are both 0.1mol/L;

Step ₃ , NaOH-Na2SO3 mixed solution described in step ₂ is added in reaction flask 3 as solution medium 2, and the graphene macroscopic material described in step 1 is added in reaction flask 3 as catalyst packing 5, and described catalyst The amount of filler 5 added is: add 1g of catalyst filler 5 per liter of solution medium 2, then use the heater 4 to heat the temperature of the solution medium 2 to 70°C, and then use the _CO gas cylinder 11 to pass CO into the reaction bottle 3 ₂ , and adjust the flow rate of _CO2 to 100mL/min through the flow regulating valve 10, and finally turn on the ultraviolet lamp 6, and carry out the photocatalytic reduction _CO2 treatment under the condition that the light intensity of ultraviolet light is 400μW/ ^cm2 . Methanol is obtained in the collection tank 8.

Fig. 4 is the SEM picture of the graphene macro material (RGO) prepared in the present embodiment. It can be seen from Figure 4 that the graphene macroscopic material (RGO) prepared in this example presents an obvious two-dimensional graphene sheet structure on the microstructure, and these flexible sheets are stacked and staggered during the assembly process, forming a well-developed structure. The network pore structure has a size distribution in the micron to submicron range. This special three-dimensional network pore forms a smooth mass transfer channel inside the graphene macrobody, which can provide a good microenvironment and a fast charge transfer path for chemical reactions.

Fig. 5 is the XRD spectrum of the graphitized carbon (TXC) prepared in this embodiment. It can be seen from Figure 5 that the graphitized carbon (TXC) obtained by high temperature treatment has very sharp characteristic diffraction peaks near 2θ=26.5°, forming a very obvious crystal structure, and the layers of aromatic ring carbon network are relatively large, and the layers are stacked. High, which is basically consistent with the XRD pattern of high-purity graphite, indicating that the degree of graphitization of graphitized carbon is very high.

Fig. 6 is the XRD spectrum of the graphene macroscopic material (RGO) and coal-based graphene oxide (CGO) prepared in this embodiment. It can be seen from Figure 6 that after the graphitized carbon is oxidized into coal-based graphene oxide (CGO) by a strong oxidant, the characteristic peak of graphitized carbon at 2θ=26.5° basically disappears, and a new characteristic diffraction peak appears at 2θ=11° , indicating that a large number of oxygen-containing functional groups were introduced into the interlayer of TXC. However, the graphene macroscopic material synthesized by coal-based graphene oxide by chemical reduction method has no obvious sharp diffraction peak, and there is only a broadened diffraction peak near 2θ=26°, which indicates that coal-based graphene oxide is reduced. During the process, the oxygen-containing functional groups gradually fall off, the original interlayer ordered stacking structure is destroyed, and a graphene macroscopic material composed of single-layer or few-layer graphene sheets stacked and folded is obtained.

Fig. 7 is the infrared spectrogram of the graphene macroscopic material (RGO) and coal-based graphene oxide (CGO) prepared in this embodiment. It can be seen from Figure 7 that coal-based graphene oxide (CGO) has a stretching vibration peak of C=C in the graphene crystal ^sp2 structure at 1630cm- ¹ , and the absorption peak at 1740cm ^-1 is graphite oxide The stretching vibration peak of C=O on the carboxyl group, and the absorption peak at 870cm ^-1 is the vibration absorption peak of the epoxy group. From the above, it can be seen that the surface of the coal-based graphene oxide obtained by oxidation with a strong oxidant contains abundant carboxyl groups, Functional groups such as hydroxyl groups, the presence of these oxygen-containing functional groups can make coal-based graphene oxide have good hydrophilicity. Compared with coal-based graphene oxide, the infrared absorption peak of the graphene macroscopic material sample obtained by chemical reduction is weakened to a certain extent, indicating that some oxygen-containing functional groups have been removed after chemical reduction. , the absorption peak at 1562 cm ^-1 is attributed to the skeleton vibration peak of graphene sheet.

Raman spectroscopy is a powerful tool for studying graphene-based materials and can be used to distinguish ordered and disordered carbon crystal structures. In the Raman spectrum of carbon materials, there are two important characteristic peaks at the positions of 1350cm ^-1 and 1580cm ^-1 , which are called D peak and G peak respectively. Among them, the D peak is induced by the disorder or structural defects inside the carbon material, indicating the degree of disorder and defect inside the material; the G peak mainly reflects the degree of graphitization of the carbon material. I _D /I _G represents the relative intensity between the D peak and the G peak, which can reflect the degree of disorder and defect density of the sample. The larger the ratio, the worse the order of the carbon material crystal structure and the more defects. many. Carbon materials also have a 2D peak near 2700cm ^-1 , which originates from the intervalley double resonance of Raman scattering, and is generally used to judge the difference between bulk graphite and few-layer graphite (or graphene). I _G /I _2D qualitatively reflects the number of single-layer graphene in few-layer graphitic carbon materials. The smaller the ratio of I _G /I _2D , the smaller the number of graphene layers. It can be seen from Figure 8 that there are both _D peaks and _G peaks in the graphene macroscopic material, and the ID/IG value is about 1.00, indicating that the prepared graphene macroscopic material has a high degree of internal disorder and a large degree of defects. In addition, near 2700cm ^-1 , RGO also has a weaker and broadened 2D peak, and its I _G /I _2D values are larger, indicating that the prepared RGO has more layers.

Graphene macroscopic materials (RGO) and coal-based graphene oxide (CGO) were used as photocatalysts under ultraviolet light conditions, and the catalytic activities of the two on the photocatalytic reduction process of _CO2 were respectively investigated, and the photocatalytic reactions under different photocatalysts were obtained. The result is shown in Figure 9. It can be seen from Figure 9 that under the same catalyst, the yield of methanol increases with the prolongation of the reaction time, because the adsorption of _CO2 is a dynamic accumulation process, and the yield of methanol is also a dynamic accumulation process. Using sheet CGO as catalyst for photocatalytic reduction of CO ₂ , the highest yield of methanol is only 5.34μmol/g·cat. When the graphene macrostructure RGO was used as the catalyst for the photocatalytic reduction of CO ₂ , the methanol yield could reach up to 65.91 μmol/g cat under the same conditions. This is because the prepared RGO has a well-developed three-dimensional network pore structure and multi-layered structure. During the reaction process, the interior of RGO can absorb a large amount of CO ₂ , increasing the residence time of CO ₂ gas in the reaction system, which is beneficial to CO ₂ The gas is in full contact with the catalyst and the reaction medium; secondly, this special mesh structure forms a smooth mass transfer channel inside, providing a good microenvironment for chemical reactions and a path for rapid charge transfer; in addition, the RGO surface retains The incomplete reduction of oxygen-containing functional groups and active sites is also beneficial to improve its photocatalytic performance.

Example 3

In conjunction with Fig. 1 to 3, the present embodiment utilizes the equipment described in embodiment 1 to carry out graphene macro material photocatalytic reduction CO _The method for preparing methanol comprises the following steps:

Step 1, using anthracite as a raw material to prepare graphene macroscopic materials, the specific process is:

Step 101: Crushing, sieving, and ball milling the anthracite in sequence to obtain ultrafine coal powder with a particle size D ₉₀ ≤ 20 μm, and then placing the ultrafine coal powder in a graphite crucible and keeping it warm at a temperature of 2500°C 3.5h, obtain graphitized carbon;

Step 102, using the graphitized carbon described in step 101 as a precursor, adopting the modified Hummers method to prepare coal-based graphene oxide, the specific process is: graphitized carbon, sodium nitrate, potassium permanganate and 98% mass concentration Concentrated sulfuric acid is mixed evenly at a mass ratio of 1:0.5:5:30, stirred at 20°C for 10minmin, then heated to 30°C and stirred for 150min, then heated to 90°C and stirred for 20min, then added deionized water to dilute Finally, adopt the method of dripping to add the hydrogen peroxide solution whose mass concentration is 30%, carry out pickling, water washing, filtration and drying treatment successively after stirring evenly, obtain coal-based graphene oxide; The addition amount of described deionized water is graphitization 40 times of charcoal quality, the add-on of described hydrogen peroxide solution is equal to the quality of potassium permanganate;

Step 103, using the coal-based graphene oxide described in step 102 as a raw material, adopting a chemical reduction self-assembly method to prepare a coal-based graphene hydrogel, the specific process is: adding the coal-based graphene oxide to deionized water for ultrasonic dispersion Uniformly, to obtain an aqueous solution of coal-based graphene oxide, and then mix the aqueous solution of coal-based graphene oxide with ethylenediamine to obtain a mixed solution, and then keep the mixed solution at a temperature of 90°C for 8 hours, and after natural cooling Obtain coal-based graphene hydrogel; the concentration of the coal-based graphene oxide aqueous solution is 6g/L, and the mass ratio of coal-based graphene oxide and ethylenediamine in the mixed solution is 0.2:1;

Step 104, freeze-drying the coal-based graphene hydrogel described in step 103 at a temperature of -15°C for 36 hours to obtain an aerogel;

Step 105. Under the protection of an inert atmosphere, the airgel described in step 104 is heated to 550° C. at a heating rate of 10° C./min, then annealed at a constant temperature for 4 hours, and the coal-based graphene macroscopic material is obtained after natural cooling;

Step 2, using deionized water as a solvent to prepare NaOH-Na ₂ SO ₃ mixed solution, the concentrations of NaOH and Na ₂ SO ₃ in the NaOH-Na ₂ SO ₃ mixed solution are both 0.05mol/L;

Step ₃ , NaOH-Na2SO3 mixed solution described in step ₂ is added in reaction flask 3 as solution medium 2, and the graphene macroscopic material described in step 1 is added in reaction flask 3 as catalyst packing 5, and described catalyst The amount of filler 5 added is: add 2g of catalyst filler 5 per liter of solution medium 2, then use the heater 4 to heat the temperature of the solution medium 2 to 72°C, and then use the _CO gas cylinder 11 to pass CO into the reaction bottle 3 ₂ , and adjust the flow rate of _CO2 to 150mL/min through the flow regulating valve 10, and finally turn on the ultraviolet lamp 6, and carry out the photocatalytic reduction _CO2 treatment under the condition that the light intensity of ultraviolet light is 300μW/ ^cm2 . Methanol is obtained in the collection tank 8.

In this example, anthracite is used as a raw material to prepare graphene macroscopic materials, which have a developed three-dimensional network pore structure and multi-sheet layered structure, and can absorb a large amount of CO ₂ in the reaction process of photocatalytic reduction of CO ₂ to prepare methanol, improving the The residence time of CO ₂ gas in the reaction system is conducive to the full contact of CO ₂ gas with the catalyst and the reaction medium; secondly, this special mesh structure forms a smooth mass transfer channel inside it, providing a good microscopic environment for chemical reactions. The environment and the path for rapid charge transfer; in addition, the oxygen-containing functional groups and active sites that are not completely reduced on the surface of graphene macroscopic materials are also conducive to improving its photocatalytic performance. In this embodiment, the graphene macroscopic material is used as the photocatalyst, which has good catalytic effect, high catalytic efficiency and high methanol yield.

Example 4

In conjunction with Fig. 1 to 3, the present embodiment utilizes the equipment described in embodiment 1 to carry out graphene macro material photocatalytic reduction CO _The method for preparing methanol comprises the following steps:

Step 1, using anthracite as a raw material to prepare graphene macroscopic materials, the specific process is:

Step 101: Crushing, sieving and ball milling the anthracite in sequence to obtain ultra-fine coal powder with a particle size D ₉₀ ≤ 20 μm, and then placing the ultra-fine coal powder in a graphite crucible and keeping it warm at a temperature of 2600°C 2.5h, obtain graphitized carbon;

Step 102, using the graphitized carbon described in step 101 as a precursor, adopting the modified Hummers method to prepare coal-based graphene oxide, the specific process is: graphitized carbon, sodium nitrate, potassium permanganate and 98% mass concentration Concentrated sulfuric acid is mixed evenly at a mass ratio of 1:1:5:30, stirred at 0°C for 10 minutes, then heated to 30°C and stirred for 150 minutes, then heated to 90°C and stirred for 20 minutes, then diluted with deionized water Finally, adopt the method of dripping to add the hydrogen peroxide solution whose mass concentration is 30%, carry out pickling, water washing, filtration and drying treatment successively after stirring evenly, obtain coal-based graphene oxide; The addition amount of described deionized water is graphitization 60 times of charcoal quality, the add-on of described hydrogen peroxide solution is equal to the quality of potassium permanganate;

Step 103, using the coal-based graphene oxide described in step 102 as a raw material, adopting a chemical reduction self-assembly method to prepare a coal-based graphene hydrogel, the specific process is: adding the coal-based graphene oxide to deionized water for ultrasonic dispersion Uniformly, to obtain a coal-based graphene oxide aqueous solution, and then mix the coal-based graphene oxide aqueous solution with ethylenediamine to obtain a mixed solution, and then keep the mixed solution at a temperature of 90 ° C for 3 hours, and after natural cooling Obtain coal-based graphene hydrogel; the concentration of the coal-based graphene oxide aqueous solution is 2g/L, and the mass ratio of coal-based graphene oxide and ethylenediamine in the mixed solution is 0.2:1;

Step 104, freeze-drying the coal-based graphene hydrogel described in step 103 at a temperature of -55°C for 36 hours to obtain an aerogel;

Step 105. Under the protection of an inert atmosphere, the airgel described in step 104 is heated up to 850° C. at a heating rate of 5° C./min, then annealed at a constant temperature for 1 hour, and the coal-based graphene macroscopic material is obtained after natural cooling;

Step 2, using deionized water as a solvent to prepare NaOH-Na ₂ SO ₃ mixed solution, the concentrations of NaOH and Na ₂ SO ₃ in the NaOH-Na ₂ SO ₃ mixed solution are both 0.1mol/L;

Step ₃ , NaOH-Na2SO3 mixed solution described in step ₂ is added in reaction flask 3 as solution medium 2, and the graphene macroscopic material described in step 1 is added in reaction flask 3 as catalyst packing 5, and described catalyst The amount of filler 5 added is: add 5g of catalyst filler 5 per liter of solution medium 2, then use the heater 4 to heat the temperature of the solution medium 2 to 68°C, and then use the _CO gas cylinder 11 to pass CO into the reaction bottle 3 ₂ , and adjust the flow rate of _CO2 to 50mL/min through the flow regulating valve 10, and finally turn on the ultraviolet lamp 6, and carry out the photocatalytic reduction _CO2 treatment under the condition that the light intensity of ultraviolet light is 500μW/ ^cm2 , and the condensate Methanol is obtained in the collection tank 8.

In this example, anthracite is used as a raw material to prepare graphene macroscopic materials, which have a developed three-dimensional network pore structure and multi-sheet layered structure, and can absorb a large amount of CO ₂ in the reaction process of photocatalytic reduction of CO ₂ to prepare methanol, improving the The residence time of CO ₂ gas in the reaction system is conducive to the full contact of CO ₂ gas with the catalyst and the reaction medium; secondly, this special mesh structure forms a smooth mass transfer channel inside it, providing a good microscopic environment for chemical reactions. The environment and the path for rapid charge transfer; in addition, the oxygen-containing functional groups and active sites that are not completely reduced on the surface of graphene macroscopic materials are also conducive to improving its photocatalytic performance. In this embodiment, the graphene macroscopic material is used as the photocatalyst, which has good catalytic effect, high catalytic efficiency and high methanol yield.

Example 5

In conjunction with Fig. 1 to 3, the present embodiment utilizes the equipment described in embodiment 1 to carry out graphene macro material photocatalytic reduction CO _The method for preparing methanol comprises the following steps:

Step 1, using anthracite as a raw material to prepare graphene macroscopic materials, the specific process is:

Step 101: Crushing, sieving and ball milling the anthracite in sequence to obtain ultra-fine coal powder with a particle size D ₉₀ ≤ 20 μm, then placing the ultra-fine coal powder in a graphite crucible and keeping it warm at a temperature of 2400°C 3.5h, obtain graphitized carbon;

Step 102, using the graphitized carbon described in step 101 as a precursor, adopting the improved Hummers method to prepare coal-based graphene oxide, the specific process is: graphitized carbon, sodium nitrate, potassium permanganate and 98% mass concentration Concentrated sulfuric acid is mixed evenly at a mass ratio of 1:0.5:5:40, stirred at 20°C for 50 minutes, then heated to 40°C and stirred for 100 minutes, then heated to 100°C and stirred for 10 minutes, then diluted with deionized water Finally, adopt the method of dripping to add the hydrogen peroxide solution whose mass concentration is 30%, carry out pickling, water washing, filtration and drying treatment successively after stirring evenly, obtain coal-based graphene oxide; The addition amount of described deionized water is graphitization 40 times of the charcoal quality, the addition of the hydrogen peroxide solution is equal to the quality of potassium permanganate;

Step 103, using the coal-based graphene oxide described in step 102 as a raw material, adopting a chemical reduction self-assembly method to prepare a coal-based graphene hydrogel, the specific process is: adding the coal-based graphene oxide to deionized water for ultrasonic dispersion Uniformly, to obtain a coal-based graphene oxide aqueous solution, and then mix the coal-based graphene oxide aqueous solution with ethylenediamine to obtain a mixed solution, and then keep the mixed solution at a temperature of 120 ° C for 8 hours, and after natural cooling Obtain coal-based graphene hydrogel; the concentration of the coal-based graphene oxide aqueous solution is 6g/L, and the mass ratio of coal-based graphene oxide and ethylenediamine in the mixed solution is 0.75:1;

Step 104, freeze-drying the coal-based graphene hydrogel described in step 103 at a temperature of -15°C for 48 hours to obtain an aerogel;

Step 105. Under the protection of an inert atmosphere, the airgel described in step 104 is heated up to 850° C. at a heating rate of 10° C./min, then annealed at a constant temperature for 4 hours, and the coal-based graphene macroscopic material is obtained after natural cooling;

Step 2, using deionized water as a solvent to prepare NaOH-Na ₂ SO ₃ mixed solution, the concentrations of NaOH and Na ₂ SO ₃ in the NaOH-Na ₂ SO ₃ mixed solution are both 0.15mol/L;

Step ₃ , NaOH-Na2SO3 mixed solution described in step ₂ is added in reaction flask 3 as solution medium 2, and the graphene macroscopic material described in step 1 is added in reaction flask 3 as catalyst packing 5, and described catalyst The amount of filler 5 added is: add 0.5g of catalyst filler 5 per liter of solution medium 2, then use the heater 4 to heat the temperature of the solution medium 2 to 72°C, and then use the _CO2 gas cylinder 11 to pass into the reaction bottle 3 CO ₂ , and adjust the flow of CO ₂ to 150mL/min through the flow regulating valve 10, and finally turn on the ultraviolet lamp 6, and carry out photocatalytic reduction of CO ₂ under the condition that the intensity of ultraviolet light is 300 μW/cm ² . Methanol is obtained in the liquid collection tank 8.

In this example, anthracite is used as a raw material to prepare graphene macroscopic materials, which have a developed three-dimensional network pore structure and multi-sheet layered structure, and can absorb a large amount of CO ₂ in the reaction process of photocatalytic reduction of CO ₂ to prepare methanol, improving the The residence time of CO ₂ gas in the reaction system is conducive to the full contact of CO ₂ gas with the catalyst and the reaction medium; secondly, this special mesh structure forms a smooth mass transfer channel inside it, providing a good microscopic environment for chemical reactions. The environment and the path for rapid charge transfer; in addition, the oxygen-containing functional groups and active sites that are not completely reduced on the surface of graphene macroscopic materials are also conducive to improving its photocatalytic performance. In this embodiment, the graphene macroscopic material is used as the photocatalyst, which has good catalytic effect, high catalytic efficiency and high methanol yield.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (8)

1. a kind of graphene macroscopic material photo catalytic reduction CO₂The method for preparing methanol, it is characterised in that what this method was used sets It is standby to include being provided with setting in multiple uviol lamps (6), the reaction chamber (1) on reaction chamber (1), the inwall of the reaction chamber (1) There is the reaction bulb (3) for containing solution medium (2), the bottom of the reaction bulb (3) is provided with for the solution medium (2) heater (4) heated, the top of the reaction bulb (3) is connected with condenser pipe (7), the condenser pipe (7) and condensation Liquid collecting tank (8) is connected, and the bottom of the reaction bulb (3) passes through CO₂Pipeline (9) is with being located at the CO of reaction chamber (1) outside₂Gas cylinder (11) connect, be provided with the reaction bulb (3) on porous barrier (12), the porous barrier (12) and be provided with catalyst filling (5), the CO₂Flow control valve (10) is provided with pipeline (9)；

Graphene macroscopic material photo catalytic reduction CO is carried out using the equipment₂The method for preparing methanol comprises the following steps：

Step 1: using anthracite to prepare graphene macroscopic material for raw material；

Step 2: using deionized water to prepare NaOH-Na for solvent₂SO₃Mixed solution, the NaOH-Na₂SO₃In mixed solution NaOH and Na₂SO₃Concentration be 0.05mol/L~0.15mol/L；

Step 3: by NaOH-Na described in step 2₂SO₃Mixed solution is added in reaction bulb (3) as solution medium (2), will Graphene macroscopic material described in step one is added in reaction bulb (3) as catalyst filling (5), then utilizes heater (4) The temperature of solution medium (2) is heated to 68 DEG C~72 DEG C, CO is utilized afterwards₂Gas cylinder (11) is passed through CO into reaction bulb (3)₂, and By flow control valve (10) by CO₂Flow be adjusted to 50mL/min~150mL/min, finally open uviol lamp (6), ultraviolet The intensity of illumination of light is 300 μ W/cm²~500 μ W/cm²Under conditions of carry out photo catalytic reduction CO₂Processing, in condensate liquid collecting tank (8) methanol is obtained in.

2. graphene macroscopic material photo catalytic reduction CO according to claim 1₂The method for preparing methanol, it is characterised in that： The reaction chamber (1) is closed at both ends columnar structured, and the quantity of the uviol lamp (6) is six, six uviol lamps (6) uniform ring cloth is on the inwall of reaction chamber (1).

3. graphene macroscopic material photo catalytic reduction CO according to claim 1₂The method for preparing methanol, it is characterised in that： The material of the reaction bulb (3) is quartz glass.

4. graphene macroscopic material photo catalytic reduction CO according to claim 1₂The method for preparing methanol, it is characterised in that： Hole in the porous barrier (12) is circular port, and the aperture of the circular port is 0.5mm~1mm.

5. graphene macroscopic material photo catalytic reduction CO according to claim 1₂The method for preparing methanol, it is characterised in that The detailed process for using anthracite to prepare graphene macroscopic material for raw material described in step one is：

Step 101, anthracite crushed successively, is sieved and ball-milling treatment, obtaining granularity D₉₀≤ 20 μm of microfine coal, so The microfine coal is placed in graphite crucible afterwards, 2.5h~3.5h is incubated under conditions of temperature is 2400 DEG C~2600 DEG C, Obtain graphitized charcoal；

Step 102, using graphitized charcoal described in step 101 as presoma, using improvement Hummers methods prepare coal base graphite oxide Alkene；

Step 103, using the graphene oxide of coal base described in step 102 as raw material, coal base is prepared using electronation self-assembly method Graphene hydrogel；

Step 104, by the graphene of coal base described in step 103 hydrogel temperature be freeze under conditions of -55 DEG C~-15 DEG C it is dry Dry 36h~48h, obtains aeroge；

Step 105, under inert atmosphere protection, by aeroge described in step 104 with 5 DEG C/min~10 DEG C/min heating speed Rate is warming up to constant temperature 1h~4h after 550 DEG C~850 DEG C and made annealing treatment, and the macroscopical material of coal base graphene is obtained after natural cooling Material.

6. graphene macroscopic material photo catalytic reduction CO according to claim 5₂The method for preparing methanol, it is characterised in that Used described in step 102 improvement Hummers methods prepare the detailed process of coal base graphene oxide for：By graphitized charcoal, nitric acid Sodium, potassium permanganate and mass concentration are 98% concentrated sulfuric acid in mass ratio 1: (0.5~1): 5: after (30~40) are well mixed, Temperature be 0 DEG C~20 DEG C under conditions of stir 10min~50min, then heat to 30 DEG C~40 DEG C stirring 100min~ 300min, is warming up to stirring 10min~20min after 90 DEG C~100 DEG C, after addition deionized water is diluted, using drop afterwards Plus method add mass concentration be 30% hydrogen peroxide solution, carried out successively after stirring pickling, washing, filtering and drying Processing, obtains coal base graphene oxide；The addition of the deionized water is 40~60 times of graphitized charcoal quality, the dioxygen The addition of the aqueous solution is equal with the quality of potassium permanganate.

7. graphene macroscopic material photo catalytic reduction CO according to claim 5₂The method for preparing methanol, it is characterised in that Used described in step 103 electronation self-assembly method prepare the detailed process of coal base graphene hydrogel for：By the coal base Graphene oxide adds ultrasonic disperse in deionized water and uniformly, coal base graphene oxide water solution is obtained, then by the coal base Graphene oxide water solution is well mixed with ethylenediamine obtains mixed liquor, is afterwards 90 DEG C~120 in temperature by the mixed liquor Coal base graphene hydrogel is obtained after being incubated 3h~8h, natural cooling under conditions of DEG C；The coal base graphene oxide water solution Concentration be 2g/L~6g/L, the mass ratio of coal base graphene oxide and ethylenediamine is (0.2~0.75) in the mixed liquor: 1.

8. graphene macroscopic material photo catalytic reduction CO according to claim 1 or 5₂The method for preparing methanol, its feature exists In the addition of catalyst filling described in step 3 (5) is：0.5g~5g catalyst is added in every liter of solution medium (2) to fill out Expect (5).