Composite asphalt-based active carbon preparation method and supercapacitor

[0039] The invention provides a method for preparing composite pitch-based activated carbon, which includes the following steps:

[0040] A) After mixing the molten matrix pitch with graphene oxide, a mixture is obtained;

[0041] B) Under the conditions of inert gas and/or nitrogen, the mixture obtained in the above steps is coked and reduced to obtain mixed green coke;

[0042] C) After crushing the mixed green coke obtained in the above steps and mixing it with alkali again, it is pre-activated and activated under inert gas and/or nitrogen conditions to obtain a semi-finished product;

[0043] D) After washing and drying the semi-finished product obtained in the above steps, it is subjected to heat treatment under protective gas conditions to obtain composite pitch-based activated carbon.

[0044] The present invention first mixes the molten matrix pitch and graphene oxide to obtain a mixture.

[0045] The present invention does not have any special restrictions on the base pitch. The base pitch used to prepare pitch coke-based activated carbon is well known to those skilled in the art. Those skilled in the art can make selections and adjustments according to actual production conditions, product requirements and quality requirements. The preferred base pitch of the present invention includes coal tar pitch and/or petroleum pitch, more preferably coal tar pitch and/or petroleum pitch, more specifically preferably a carbon content greater than or equal to 90%, and a sulfur content less than or equal to 0.5% Of the substrate pitch.

[0046] The graphene oxide of the present invention is preferably graphene oxide powder, more preferably a single-layer graphene oxide powder; the single-layer rate is more preferably higher than or equal to 95%. The present invention does not particularly limit the sheet diameter of the graphene oxide, as long as the sheet diameter of graphene oxide is well known to those skilled in the art, and those skilled in the art can select and adjust according to the actual production situation, product requirements and quality requirements. The average sheet diameter of the graphene oxide of the present invention is preferably 1-50 μm, more preferably 5-45 μm, more preferably 10-40 μm, and most preferably 20-30 μm. The present invention has no particular limitation on the source of the single-layer graphene oxide, as long as the source of the single-layer graphene oxide is well known to those skilled in the art, it can be commercially available or can be prepared according to a conventional preparation method. The present invention does not particularly limit the amount of graphene oxide added. Those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. The quality of the graphene oxide of the present invention accounts for the mass of the base pitch. The ratio of is preferably 0.1% to 1%, more preferably 0.2% to 0.9%, more preferably 0.3% to 0.8%, most preferably 0.5% to 0.6%.

[0047] The present invention does not particularly limit the mixing temperature. Those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. The mixing temperature of the present invention is preferably 100-180°C, more preferably 110 -170°C, more preferably 120-160°C, most preferably 130-150°C. The present invention has no particular restrictions on the specific steps and methods of mixing, as long as the mixing steps and methods are well known to those skilled in the art, those skilled in the art can make selections and adjustments according to actual production conditions, product requirements and quality requirements. The invention is to form a uniformly compounded graphene oxide composite pitch and improve the performance of the final composite material. The specific steps of the mixing are preferably:

[0048] Under the condition of 150~180℃, stir and mix the molten matrix pitch and graphene oxide for 10~30min, then shear and mix for 60~90min; then cool to 100~120℃ and place for 30-60min, then cut again Cut and mix for 60-90 minutes to obtain a mixture, namely graphene oxide composite pitch.

[0049] According to the present invention, 150-180°C, more preferably 155-175°C, most preferably 160-170°C; the stirring and mixing time is preferably 10-30 minutes, more preferably 12-28 minutes, and more preferably 14-26 minutes , Most preferably 16 to 24 minutes. The shear mixing time of the present invention is preferably 60-90 min, more preferably 65-85 min, and most preferably 70-80 min; the present invention has no special restrictions on other conditions of the shear mixing, and those skilled in the art can follow The actual production conditions, product requirements and quality requirements are selected and adjusted. The rotation speed of the shear mixing of the present invention is preferably 90-240 rpm, more preferably 110-220 rpm, more preferably 130-200 rpm, and most preferably 150-180 rpm; The present invention does not particularly limit the shearing and mixing equipment. Those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. The shearing and mixing equipment of the present invention is preferably a shearing machine. The cooling temperature of the present invention is preferably 100 to 120°C, more preferably 102 to 118°C, more preferably 105 to 115°C, most preferably 108 to 112°C; the time of leaving is preferably 30 to 60 minutes, more preferably It is 35 to 55 minutes, most preferably 40 to 50 minutes. The time for the reshearing and mixing of the present invention is preferably 60 to 90 min, more preferably 65 to 85 min, and most preferably 70 to 80 min; the present invention has no special restrictions on other conditions for the reshearing and mixing, and those skilled in the art It can be selected and adjusted according to actual production conditions, product requirements and quality requirements. The re-shearing and mixing speed of the present invention is preferably 90-240 rpm, more preferably 110-220 rpm, more preferably 130-200 rpm, most preferably 150 ~180rmp.

[0050] The present invention forms a uniformly composite graphene oxide composite pitch (mixture) by combining graphene oxide and pitch at a certain temperature through a special shearing and mixing step, which provides advantages for improving the performance of composite pitch-based activated carbon in the later stage. Foundation.

[0051] In the present invention, under the conditions of inert gas and/or nitrogen, the mixture obtained in the above steps is coked and reduced to obtain mixed green coke.

[0052] The present invention does not particularly limit the inert gas, and those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. The present invention is specifically preferably argon. The present invention has no particular limitation on the conditions of the coking reduction, as long as the conditions of pitch coking are well known to those skilled in the art, and those skilled in the art can make selections and adjustments according to actual production conditions, product requirements and quality requirements. The present invention The temperature of the coking reduction is preferably 450 to 500°C, more preferably 455 to 495°C, more preferably 460 to 490°C, most preferably 470 to 480°C; the coking reduction time is preferably 6 to 12 hours, more preferably It is preferably 7 to 11 hours, most preferably 8 to 10 hours. The present invention has no particular limitation on the coking reduction equipment, as long as the coking reduction equipment is well known to those skilled in the art, the coking reduction equipment of the present invention is preferably a coking furnace.

[0053] In the present invention, the mixed green coke obtained in the above steps is crushed and mixed with alkali again, and then pre-activated and activated under the conditions of inert gas and/or nitrogen to obtain a semi-finished product.

[0054] The present invention has no particular limitation on the particle size of the mixed green coke after pulverization. Those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. The particle size of the mixed green coke after pulverization of the present invention is preferably It is 50-100 μm, more preferably 60-90 μm, most preferably 70-80 μm. The present invention has no special restrictions on the alkali, as long as the alkali used for activating pitch coke is well known to those skilled in the art. Those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. It preferably includes one or more of potassium hydroxide, sodium hydroxide, lithium hydroxide and calcium hydroxide, more preferably potassium hydroxide, sodium hydroxide, lithium hydroxide or calcium hydroxide, more preferably potassium hydroxide, Sodium hydroxide or calcium hydroxide, most preferably potassium hydroxide. The present invention has no other special restrictions on the alkali. Those skilled in the art can select and adjust according to the actual production situation, product requirements and quality requirements. The present invention is convenient for mixing. The alkali is preferably a granular alkali. The particle size of the base is preferably 10 to 300 μm, more preferably 50 to 250 μm, more preferably 100 to 200 μm, and most preferably 130 to 170 μm. The present invention does not particularly limit the amount of the alkali. Those skilled in the art can select and adjust according to the actual production situation, product requirements and quality requirements. The mass ratio of the mixed green coke to the alkali in the present invention is preferably 1: (0.5 ~5), more preferably 1: (1 to 4.5), more preferably 1: (1.5 to 4), most preferably 1: (2 to 3.5).

[0055] The present invention does not particularly limit the inert gas, and those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. The present invention is specifically preferably argon. The present invention has no special restrictions on the re-mixing. Those skilled in the art can make selection and adjustments according to actual production conditions, product requirements and quality requirements. The present invention is preferably mixing with a mixer.

[0056] The present invention has no special restrictions on the pre-activation conditions. The pre-activation conditions of pitch green coke are well known to those skilled in the art. Those skilled in the art can make selections and adjustments according to actual production conditions, product requirements and quality requirements. The pre-activation temperature of the present invention is preferably 350-500°C, more preferably 375-475°C, more preferably 400-450°C, most preferably 410-440°C; the pre-activation time is preferably 1-4 Hour, more preferably 1.5 to 3.5 hours, most preferably 2 to 3 hours. The present invention has no special restrictions on the activation conditions. The conditions for the activation of pitch green coke well known to those skilled in the art can be used. Those skilled in the art can select and adjust according to the actual production situation, product requirements and quality requirements. The present invention The activation temperature is preferably 700 to 950°C, more preferably 725 to 925°C, more preferably 750 to 900°C, and most preferably 800 to 850°C; the activation time is preferably 0.5 to 4 hours, more preferably It is 1 to 3.5 hours, more preferably 1.5 to 3 hours, and most preferably 2 to 2.5 hours. The present invention has no particular limitation on the pre-activation and activation equipment. The equipment for pre-activation and activation of pitch green coke well known to those skilled in the art can be used. Those skilled in the art can carry out the process according to actual production conditions, product requirements and quality requirements. For selection and adjustment, the pre-activation and activation equipment of the present invention is preferably a crucible.

[0057] In the present invention, the semi-finished product obtained in the above steps is washed and dried, and then subjected to heat treatment under protective gas conditions to obtain composite pitch-based activated carbon.

[0058] The present invention has no particular limitation on the washing steps. The washing steps after the activation of pitch green coke is well known to those skilled in the art. Those skilled in the art can make selections and adjustments according to actual production conditions, product requirements and quality requirements. The specific washing steps of the present invention preferably include natural cooling, water washing, acid washing and water washing in sequence, more specifically, natural cooling, water washing to neutrality, acid washing, and water washing to neutrality. The acid for pickling of the present invention is preferably one or more of hydrochloric acid, nitric acid and phosphoric acid; the temperature of the washing is preferably 20-100°C, more preferably 40-80°C, most preferably 50-100°C . The present invention has no special restrictions on the drying steps, and those skilled in the art can make selections and adjustments according to actual production conditions, product requirements and quality requirements.

[0059] The present invention does not have special restrictions on the protective gas, as long as the protective gas is well known to those skilled in the art, those skilled in the art can select and adjust according to actual production conditions, product requirements and quality requirements. The sexual gas preferably includes one or more of hydrogen, ammonia, nitrogen, and inert gas, and more preferably one or two of hydrogen, ammonia, nitrogen, and argon. The present invention does not particularly limit the heat treatment conditions. The heat treatment steps for preparing activated carbon from pitch coke well known to those skilled in the art are sufficient. Those skilled in the art can make selections and adjustments according to actual production conditions, product requirements and quality requirements. The temperature of the heat treatment of the invention is preferably 700 to 900°C, more preferably 720 to 880°C, more preferably 750 to 850°C, and most preferably 770 to 830°C; the heat treatment time is preferably 1 to 4 hours, more preferably It is preferably 1.5 to 3.5 hours, most preferably 2 to 3 hours.

[0060] In order to improve the quality of the final product, the present invention preferably includes crushing, screening and magnetic separation steps after the heat treatment; the present invention has no particular restrictions on the specific processes and conditions of the crushing, screening and magnetic separation steps, and those skilled in the art can The selection and adjustment are made according to actual production conditions, product requirements and quality requirements. The particle size after crushing in the present invention is preferably 6-10 μm, more preferably 7-9 μm.

[0061] See figure 1 , figure 1 This is an electron micrograph of the composite pitch-based activated carbon prepared by the present invention.

[0062] The present invention prepares graphene composite pitch-based activated carbon through the above steps. The present invention forms a uniformly compounded graphene oxide composite pitch (mixture) by combining graphene oxide and pitch at a certain temperature through a special shear mixing step. ), then the graphene oxide and pitch coke are reduced and activated together by high-temperature coking, and the graphene oxide forms a uniform network inside the pitch coke; at the same time, after high-temperature activation and high-temperature reduction, graphene oxide removes most of the oxygen to form graphene. As a result, a good conductive network is formed inside the activated carbon and the internal resistance of the activated carbon is reduced. The preparation method provided by the present invention effectively solves the problem that the existing activated carbon is mainly micropores, the pore size distribution is unreasonable, the alkali ratio used in the preparation process is relatively high, and the performance of the activated carbon still cannot meet the requirements for capacity and the internal resistance is relatively low. Big problem. Graphene oxide is added to the pitch and coked and reduced, and the graphene oxide forms a uniform network inside the pitch coke. The composite pitch-based activated carbon prepared by the invention has the advantages of reasonable pore size distribution, large specific surface area, low internal resistance, high capacity, low impurities and low oxygen-containing functional groups, and can be used as a super capacitor carbon to obtain a super capacitor with better performance. The experimental results show that the specific surface area of ​​the composite pitch-based activated carbon prepared by the invention is 2300~3200m 2 /g, mesoporosity is 35%-50%, average particle size is 6-10μm, nitrogen content is 1%-3%, metallic impurities <100ppm, low resistance, organic mass specific capacitance as high as 160~210F/g, good cycle stability.

[0063] The present invention also provides a supercapacitor, comprising the composite pitch-based activated carbon prepared by any one of the above technical solutions. The present invention does not particularly limit the definition of the supercapacitor, as long as the definition of the supercapacitor is well known to those skilled in the art.

[0065] Example 1

[0066] Take 500g coal tar pitch, heat it to melt, keep the temperature at 150℃; weigh 5g graphene oxide powder into the coal tar pitch, stir for 20min, then use a shearing machine to stir for 90min, shear speed 150rmp; cool to 120℃ and place 60min, then shear again for 90min to obtain coal tar pitch with fully dispersed graphene oxide;

[0067] Under the protection of nitrogen, the pitch is heated to 450°C for 8h in a coking furnace, cooled naturally, and then pulverized into a powder of 50-100μm in a pulverizer; 1500g of powdered KOH is added and mixed uniformly. Put this mixture into a metallic nickel crucible, heat it up to 450°C at a rate of 10-20°C/min and keep it for 3h under a nitrogen atmosphere; then heat it up to 750°C at a rate of 10-20°C/min to activate for 2h, and then naturally drop to room temperature . The product was dissolved in water, washed repeatedly to neutrality, and then 6M hydrochloric acid was added to reflux for 2h, filtered, washed with deionized water to neutrality, and dried in vacuum. Put the obtained solid powder into a rotary kiln, raise the temperature to 800°C under 10% hydrogen-nitrogen mixture and keep it for 2h, cool down, pulverize into 6-9μm powder by secondary ball milling, and remove excess metal ions through a magnetic separator. Composite pitch-based activated carbon (pitch-based super capacitor carbon).

[0068] See figure 2 , figure 2 This is an electron micrograph of the composite pitch-based activated carbon prepared in Example 1 of the present invention.

[0069] See image 3 , image 3 This is the pore size distribution diagram of the composite pitch-based activated carbon prepared in Example 1 of the present invention.

[0070] The composite pitch-based activated carbon prepared in Example 1 above was tested, and the specific surface area of ​​the activated carbon was 3200m 2 /g, mesoporosity is 65%, average particle size is 7.4μm, nitrogen content is 1.5%, metal impurities <100ppm.

[0071] This activated carbon and the binder SBR and CMC are mixed and homogenized, uniformly coated on aluminum foil, dried, rolled, and punched to form a supercapacitor (organic series, 2.7V). When the current density is 2A/g , The mass specific capacitance is 210F/g.

[0072] Example 2

[0073] Take 200g of coal tar pitch, heat it to melt, keep the temperature at 180℃; weigh 1g of graphene oxide powder into coal tar pitch, stir for 20min, then use a shearing machine to stir for 90min at a shear speed of 150rmp; cool to 120℃ and place 60min, then shear again for 90min to obtain coal tar pitch with fully dispersed graphene oxide;

[0074] Under the protection of nitrogen, the pitch is heated to 500°C for 6h in a coking furnace, cooled naturally, and then pulverized into a powder of 50-100μm in a pulverizer; 500g powdered KOH is added and mixed uniformly. Put this mixture into a metal nickel crucible, heat it up to 450°C at a rate of 10-20°C/min and keep it for 3h under a nitrogen atmosphere; then heat it up to 750°C at a rate of 10-20°C/min to activate for 1.5h, and naturally decrease Room temperature. The product was dissolved in water, washed repeatedly to neutrality, and then 6M hydrochloric acid was added to reflux for 2h, filtered, washed with deionized water to neutrality, and dried in vacuum. Put the obtained solid powder into a rotary kiln, raise the temperature to 800°C under ammonia gas and keep it for 2h, cool down, pulverize into 6-9μm powder by secondary ball milling, and remove excess metal ions through a magnetic separator to obtain pitch-based super capacitor carbon .

[0075] The composite pitch-based activated carbon prepared in Example 2 above was tested, and the specific surface area of ​​the activated carbon was 2500m 2 /g, mesoporosity is 68%, average particle size is 6.9μm, nitrogen content is 1.6%, metal impurities <100ppm.

[0076] This activated carbon and the binder SBR and CMC are mixed and homogenized, uniformly coated on aluminum foil, dried, rolled, and punched to form a supercapacitor (organic series, 2.7V). When the current density is 2A/g , The mass specific capacitance is 190F/g.