High specific surface area activated carbon, its preparation method and use

Abstract

The application provides a preparation method of high specific surface area activated carbon, which comprises extracting a raw material capable of producing high specific surface area activated carbon from coal liquefaction pitch, and obtaining high specific surface area activated carbon through alkali activation. The application realizes resource utilization and harmless treatment of the raffinate, and achieves environmental protection, low-carbon utilization and end carbon fixation, and has a broad development prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal chemical industry, in particular to high specific surface area activated carbon, a preparation method thereof and application thereof. BACKGROUND

[0002] Coal liquefaction pitch is a by-product produced in the process of direct coal liquefaction, accounting for about 30% of the coal input. The main components of coal liquefaction pitch are heavy oil, pitch and coal liquefaction oil residue. The coal liquefaction oil residue accounts for about 50wt% of the coal liquefaction pitch, which contains unreacted inert components (homogenized inert components), minerals and catalysts, and is referred to as residue. The pitch can be used to prepare binder pitch, needle coke, high modulus carbon fiber, mesocarbon microbeads and other high-end carbon materials. At present, domestic researchers have widely studied and utilized pitch, but less studied residue due to its high content of homogenized inert components.

[0003] Activated carbon (AC) is a broad-spectrum adsorbent, and its adsorption capacity mainly depends on the specific surface area and pore size distribution of activated carbon. Conventional activated carbon has a small specific surface area (<1500m 2 / g), a wide pore size distribution (in the range of 1nm to 100nm) and poor selective adsorption, which cannot meet the special requirements of the fields of medicine, environmental protection, military and electronics, etc. Super activated carbon has a specific surface area of more than 2000m 2 / g, which is much higher than that of conventional activated carbon (generally between 300m 2 / g and 1000m 2 / g), and is also called high specific surface area activated carbon. The high adsorption performance of high specific surface area activated carbon widens the application of activated carbon, and has great application potential in the fields of gas adsorption separation storage, energy storage, catalyst carrier, heavy metal removal, high-performance capacitor, etc., and thus has been widely concerned by the world.

[0004] The raw materials for preparing high specific surface area activated carbon in China are generally coal, petroleum coke, fruit shells, coconut shells, etc. However, the cost of the above raw materials is high, especially the imported coconut shell carbonization material, which results in high production cost, high product price and difficult market promotion.

[0005] Chinese patent application CN109133055A discloses a preparation method of high-purity medium-temperature coal pitch-based super activated carbon. In the method, the sample is treated with hydrochloric acid and hydrofluoric acid in several times, and is crushed and sieved, which increases the process flow, increases the cost of raw materials, and increases the amount of acid, which will increase the problem of subsequent waste acid treatment.

[0006] Chinese patent application CN104291333A discloses a method for preparing high specific surface area mesoporous activated carbon from stone coal, wherein concentrated sulfuric acid and hydrofluoric acid are used as mixed acid liquid. The use of the mixed acid liquid will result in insoluble salt, which will block the pores of the activated carbon and affect the adsorption capacity of the activated carbon. Moreover, the waste acid is difficult to recover.

[0007] Chinese patent application CN1304788A discloses a high specific surface area activated carbon, wherein potassium hydroxide and petroleum coke are mixed at a ratio of 5:1, heated to 400°C for 1 hour, and then heated to 800°C for 1.5-2 hours to obtain the high specific surface area activated carbon. The method uses a large amount of alkali, and the petroleum coke is expensive.

[0008] Therefore, there is still a need in the art to study new activated carbon materials with high adsorption capacity and low raw material cost. SUMMARY

[0009] In view of the problems in the prior art, the present application aims to extract a raw material from coal liquefaction pitch for producing high specific surface area activated carbon. First, the coal liquefaction pitch is low in cost, and the pitch and the raffinate are separated by washing oil extraction. The raffinate is a high-quality carbon source for preparing activated carbon with high microporosity, because it contains a large amount of homogenized inert matter and belongs to condensed aromatic hydrocarbon itself, and has certain original pores. Second, the pitch is removed by washing oil extraction and solid-liquid separation, which solves the problem of pitch wrapping the raffinate and improves the surface wettability of the raffinate. Third, the added iron-based catalyst particles are nanoscale particles with fine particle size, which can realize preliminary pore formation, increase the specific surface area, facilitate sufficient contact during subsequent alkali activation, easily realize secondary pore formation, and use a small amount of alkali, so that the prepared activated carbon has a large specific surface area.

[0010] Therefore, one of the purposes of the present application is to provide a high specific surface area activated carbon with a specific surface area of 2000 m 2 / g to 3300 m 2 / g; a pore volume of 1.0 cm 3 / g to 1.9 cm 3 / g; and a pore diameter of to 1.65 wt% to 2.90 wt% of H2 adsorption under the condition of 77K, 1 bar.

[0011] In some embodiments, the high specific surface area activated carbon described in the present application has a specific surface area of 2300 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.9 cm 3 / g; and a pore diameter of to 77K, 1 bar, 1.75wt% - 2.90wt% H2 adsorption.

[0012] In some embodiments, the high specific surface area activated carbon described in the present application has a specific surface area of 2800m 2 / g to 3300m 2 / g; a pore volume of 1.3cm 3 / g to 1.6cm 3 / g; a pore diameter of to 77K, 1 bar, 1.85wt% - 2.90wt% H2 adsorption.

[0013] The second object of the present application is to provide a method for preparing high specific surface area activated carbon, which uses the following three methods to prepare high specific surface area activated carbon:

[0014] Method 1:

[0015] Step 1:

[0016] The bitumen-like substances and raffinate in the coal liquefaction pitch are separated by washing oil extraction;

[0017] Step 2:

[0018] The raffinate obtained by separation is pre-oxidized with ozone;

[0019] Step 3:

[0020] The activated carbon raw material obtained by pre-oxidation is alkali-activated to obtain high specific surface area activated carbon.

[0021] In some embodiments, in Step 1, the washing oil used for extraction has the following parameters:

[0022] Density at 20°C is not more than 1.070g / cm 3 ;

[0023] Moisture is not more than 1.0% (mass fraction);

[0024] Distillation range: distillation rate at 210°C is not higher than 3% (volume fraction), distillation rate at 300°C is not lower than 90% (volume fraction);

[0025] Chlorine content is not more than 20mg / L;

[0026] Ash content is not more than 0.1% (mass fraction);

[0027] Acid value is not more than 0.5mgKOH / g;

[0028] Phenol content is not more than 0.5% (volume fraction).

[0029] In some embodiments, in step 1, the volume to mass ratio (mL / g) of the wash oil to the coal liquefaction pitch used for extraction is 2.0:1-5.0:1, preferably 2.5:1-4.0:1, more preferably 3.0:1-3.5:1, most preferably 3.0:1.

[0030] In some embodiments, in step 1, the content of the pitch-like substance in the obtained raffinate is 1wt%-6wt%, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, preferably 1wt%-4wt%, more preferably 1wt%-2wt%.

[0031] In some embodiments, in step 2, the pre-oxidation is carried out at room temperature.

[0032] In some embodiments, in step 2, the ozone is continuously introduced into the raffinate at room temperature for 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, preferably 1.5-2.5 hours.

[0033] In some embodiments, in step 3, the base used for alkali activation is potassium hydroxide or sodium hydroxide, preferably potassium hydroxide.

[0034] In some embodiments, in step 3, the mass ratio (g / g) of the base to the raffinate used for alkali activation is 2:1-4:1, preferably 2.5:1-4:1, more preferably 3:1-3.5:1, for example, 3:1-3.2:1.

[0035] In some embodiments, in step 3, the alkali activation conditions are as follows:

[0036] After mixing the pre-oxidized activated carbon raw material with the base, calcination is carried out at a temperature of 550°C to 650°C (for example, 1-2 hours), and then calcination is carried out at a temperature of 750°C to 850°C (for example, 1-2 hours), after which the temperature is allowed to decrease to room temperature naturally, the obtained solid is added to water, stirred, and washed with water (for example, the obtained solid is added to ionized water, stirred, and washed to remove the residual base), filtered, the pH value is adjusted to about 2 with an acid, and then washed with water to neutral, dried, and a high specific surface area activated carbon is obtained.

[0037] In some embodiments, in step 3, before alkali activation, the base is ground and mixed uniformly with the pre-oxidized activated carbon raw material; or the base is pre-dissolved in water, the pre-oxidized activated carbon raw material is stirred and impregnated in the base solution, and then dried.

[0038] In some embodiments, in step 3, the acid used for adjusting pH is dilute hydrochloric acid, and the mass ratio (g / g) of dilute hydrochloric acid to the raffinate is 0.550:1-0.650:1, preferably 0.590:1-0.610:1, more preferably 0.595:1-0.605:1.

[0039] In some embodiments, in step 3, the base activation is carried out under inert gas protection.

[0040] In some embodiments, the high specific surface area activated carbon prepared has a specific surface area of 2000 m 2 / g to 3300 m 2 / g; a pore volume of 1.0 cm 3 / g to 1.9 cm 3 / g; a pore diameter of to a H2 adsorption amount of 1.65 wt%-2.90 wt% at 77K, 1 bar.

[0041] In some embodiments, the high specific surface area activated carbon prepared has a specific surface area of 2300 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.9 cm 3 / g; a pore diameter of to a H2 adsorption amount of 1.75 wt%-2.90 wt% at 77K, 1 bar.

[0042] In some embodiments, the high specific surface area activated carbon prepared has a specific surface area of 2800 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.6 cm 3 / g; a pore diameter of to a H2 adsorption amount of 1.85 wt%-2.90 wt% at 77K, 1 bar.

[0043] Method two:

[0044] Step 1:

[0045] separating the pitch-like substances in the coal liquefaction pitch and the raffinate by washing oil extraction;

[0046] Step 2:

[0047] directly subjecting the separated raffinate to base activation to obtain high specific surface area activated carbon.

[0048] In some embodiments, in step 1, the washing oil used for extraction has the following parameters:

[0049] Density at 20°C is not more than 1.070 g / cm 3 ;

[0050] Moisture is not more than 1.0% (mass fraction);

[0051] Distillation range: distillation rate at 210°C is not more than 3% (volume fraction), distillation rate at 300°C is not less than 90% (volume fraction);

[0052] Chlorine content is not more than 20 mg / L;

[0053] Ash content is not more than 0.1% (mass fraction);

[0054] Acid value is not more than 0.5 mgKOH / g;

[0055] Phenol content is not more than 0.5% (volume fraction).

[0056] In some embodiments, in step 1, the volume-mass ratio (mL / g) of the washing oil used for extraction to coal liquefied pitch is 2.0:1-5.0:1, preferably 2.5:1-4.0:1, more preferably 3.0:1-3.5:1, most preferably 3.0:1.

[0057] In some embodiments, in step 1, the content of pitch-like substances in the obtained raffinate is 1wt%-6wt%, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, preferably 1wt%-4wt%, more preferably 1wt%-2wt%.

[0058] In some embodiments, in step 2, the base used for alkaline activation is potassium hydroxide or sodium hydroxide, preferably potassium hydroxide.

[0059] In some embodiments, in step 2, the mass ratio (g / g) of the base used for alkaline activation to the raffinate is 2:1-4:1, preferably 2.5:1-4:1, more preferably 3:1-3.5:1, for example, 3:1-3.2:1.

[0060] In some embodiments, in step 2, the alkaline activation conditions are as follows:

[0061] After mixing the residue with the base, calcination is carried out at a temperature of 550-650°C (for example, for 1-2 hours), followed by calcination at a temperature of 750-850°C (for example, for 1-2 hours), and after the completion of the calcination, natural cooling to room temperature, addition of the obtained solid to water, stirring, water washing (for example, addition of the obtained solid to ionized water, stirring and water washing to wash away the residual base), filtration, adjustment of the pH value to about 2 with an acid, and water washing to neutral, drying, to obtain a high specific surface area activated carbon.

[0062] In some embodiments, in step 2, before the base activation, the base is mixed uniformly with the residue by grinding; or the base is previously dissolved in water, the residue is stirred and impregnated in the base solution, and then dried.

[0063] In some embodiments, in step 2, the acid used for the pH adjustment is dilute hydrochloric acid, and the mass ratio (g / g) of the dilute hydrochloric acid to the residue is 0.550:1-0.650:1, preferably 0.590:1-0.610:1, and more preferably 0.595:1-0.605:1.

[0064] In some embodiments, in step 2, the base activation is carried out under inert gas protection.

[0065] In some embodiments, the high specific surface area activated carbon prepared has a specific surface area of 2000 m 2 / g to 3300 m 2 / g; a pore volume of 1.0 cm 3 / g to 1.9 cm 3 / g; and a pore diameter of to a H2 adsorption amount of 1.65 wt%-2.90 wt% under the condition of 77K, 1 bar.

[0066] In some embodiments, the high specific surface area activated carbon prepared has a specific surface area of 2300 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.9 cm 3 / g; and a pore diameter of to a H2 adsorption amount of 1.75 wt%-2.90 wt% under the condition of 77K, 1 bar.

[0067] In some embodiments, the high specific surface area activated carbon prepared has a specific surface area of 2800 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.6 cm 3 / g; and a pore diameter of To 77K, 1 bar, 1.85wt% - 2.90wt% H2uptake.

[0068] Method three:

[0069] Step 1:

[0070] separating the pitch-like substances and the raffinate from the coal liquefaction pitch by washing oil extraction;

[0071] Step 2:

[0072] acid washing and deashing the raffinate obtained from the separation;

[0073] Step 3:

[0074] alkali-activating the activated carbon raw material obtained from the acid washing and deashing to obtain the high specific surface area activated carbon.

[0075] In some embodiments, in Step 1, the washing oil used for extraction has the following parameters:

[0076] density not more than 1.070 g / cm3at 20℃; 3 ;

[0077] moisture not more than 1.0% (mass fraction);

[0078] distillation range: distillation rate not higher than 3% (volume fraction) at 210℃, distillation rate not lower than 90% (volume fraction) at 300℃;

[0079] chlorine content not more than 20 mg / L;

[0080] ash content not more than 0.1% (mass fraction);

[0081] acid value not more than 0.5 mgKOH / g;

[0082] phenol content not more than 0.5% (volume fraction).

[0083] In some embodiments, in Step 1, the volume-mass ratio (mL / g) of the washing oil used for extraction to the coal liquefaction pitch is 2.0:1-5.0:1, preferably 2.5:1-4.0:1, more preferably 3.0:1-3.5:1, most preferably 3.0:1.

[0084] In some embodiments, in Step 1, the content of the pitch-like substances in the raffinate obtained from the separation is 1wt%-6wt%, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, preferably 1wt%-4wt%, more preferably 1wt%-2wt%.

[0085] In some embodiments, in step 2, the ash content of the activated carbon raw material obtained after the acid washing and ashing is 2wt% to 9wt%, for example, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%.

[0086] In some embodiments, in step 2, the acid used for the acid washing and ashing is hydrochloric acid, preferably dilute hydrochloric acid, for example, 36% hydrochloric acid.

[0087] In some embodiments, in step 2, the mass ratio (g / g) of the acid used for the acid washing and ashing to the residue is 2:1 to 4:1, preferably 2.5:1 to 3.5:1, more preferably 3:1.

[0088] In some embodiments, in step 3, the base used for the base activation is potassium hydroxide or sodium hydroxide, preferably potassium hydroxide.

[0089] In some embodiments, in step 3, the mass ratio (g / g) of the base used for the base activation to the residue is 2:1 to 4:1, preferably 2.5:1 to 4:1, more preferably 3:1 to 3.5:1, for example, 3:1 to 3.2:1.

[0090] In some embodiments, in step 3, the base activation is carried out under the following conditions:

[0091] After mixing the activated carbon raw material obtained after the acid washing and ashing with the base, calcination is carried out at a temperature of 550°C to 650°C (for example, 1 to 2 hours), followed by calcination at a temperature of 750°C to 850°C (for example, 1 to 2 hours), and after the calcination is completed, the obtained solid is allowed to naturally cool to room temperature, the obtained solid is added to water, stirred, washed with water (for example, the obtained solid is added to ionized water, stirred, and washed with water to wash away the residual base), filtered, the pH value is adjusted to about 2 with an acid, and then washed with water to neutral, dried, and a high specific surface area activated carbon is obtained.

[0092] In some embodiments, in step 3, before the base activation, the base is uniformly ground mixed with the activated carbon raw material obtained after the acid washing and ashing; or the base is previously dissolved in water, and the activated carbon raw material obtained after the acid washing and ashing is stirred and impregnated in the base solution, and then dried.

[0093] In some embodiments, in step 3, the acid used for the pH adjustment is dilute hydrochloric acid, and the mass ratio (g / g) of the dilute hydrochloric acid to the residue is 0.550:1 to 0.650:1, preferably 0.590:1 to 0.610:1, more preferably 0.595:1 to 0.605:1.

[0094] In some embodiments, in step 3, the base activation is carried out under inert gas protection.

[0095] In some embodiments, the high specific surface area activated carbon produced has a specific surface area of 2000 m 2 / g to 3300 m 2 / g; a pore volume of 1.0 cm 3 / g to 1.9 cm 3 / g; a pore diameter of to a H2 adsorption amount of 1.65 wt% - 2.90 wt% at 77K, 1 bar.

[0096] In some embodiments, the high specific surface area activated carbon produced has a specific surface area of 2300 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.9 cm 3 / g; a pore diameter of to a H2 adsorption amount of 1.75 wt% - 2.90 wt% at 77K, 1 bar.

[0097] In some embodiments, the high specific surface area activated carbon produced has a specific surface area of 2800 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.6 cm 3 / g; a pore diameter of to a H2 adsorption amount of 1.85 wt% - 2.90 wt% at 77K, 1 bar.

[0098] It is a third object of the present application to provide the use of high specific surface area activated carbon as a hydrogen adsorption carbon source.

[0099] Advantages

[0100] The present application uses coal liquefaction pitch as a raw material to produce high specific surface area activated carbon, overcoming the problems of high cost, large resource waste, and the need for a grinding process in the prior art using coal, petroleum coke, coconut shell, medium temperature coal pitch, etc. as raw materials. In particular, the present application makes full use of the raffinate obtained after washing oil extraction as a raw material for producing high specific surface area activated carbon, which has the advantages of low cost and large output. The particle size of the raffinate is about 45-74 μm, so there is no need for a grinding process.

[0101] The bitumen and the raffinate are separated by washing oil extraction, the obtained raffinate is a high-quality carbon source for preparing activated carbon with high microporosity, because it contains a large amount of homogenized inert matter and belongs to condensed ring aromatic hydrocarbon itself and has certain original pores; the bitumen is removed by washing oil extraction solid-liquid separation, the current situation that the bitumen wraps the raffinate is solved, and the surface wettability of the raffinate is improved; in the coal liquefaction process, the added iron-based catalyst particles are nano-level particles with a relatively fine particle size, and the particles can realize preliminary pore formation after being removed by acid washing, so that the specific surface area is increased, the subsequent alkali activation is facilitated, the secondary pore formation is easily realized, the amount of alkali used is relatively low, and the prepared activated carbon has a relatively large specific surface area.

[0102] The high specific surface area activated carbon with micropore concentration is obtained in the application, not only the raffinate solid waste treatment problem is solved, but also the downstream application of the high specific surface area activated carbon is wide, and the high specific surface area activated carbon can also be used as a hydrogen adsorption carbon source. The H2 adsorption capacity of the high specific surface area activated carbon prepared from the coconut shell and the raffinate of the application respectively is tested under the condition of 77K and 1 bar, and the result shows that the H2 adsorption amount of the high specific surface area activated carbon prepared from the coconut shell is low, and the adsorption amount is about 1.67wt%, the H2 adsorption amount of the high specific surface area activated carbon prepared from the raffinate of the application is as high as 2.90wt%, so the high specific surface area activated carbon prepared from the raffinate in the application has better H2 adsorption capacity.

[0103] The application realizes the resource utilization and harmless treatment of the raffinate, completes environmental protection, low-carbon utilization and end carbon sequestration, and has a broad development prospect. BRIEF DESCRIPTION OF DRAWINGS

[0104] Figure 1 The N2-77K adsorption-desorption curve (left) and the pore size distribution (right) of the high specific surface area activated carbon prepared by the method one in the embodiment 1-2 of the application are shown.

[0105] Figure 2 The N2-77K adsorption-desorption curve (left) and the pore size distribution (right) of the high specific surface area activated carbon prepared by the method one in the embodiment 1-3 of the application are shown.

[0106] Figure 3 The SEM images (left) of the raffinate before alkali activation and the SEM images (right) of the raffinate after alkali activation in the process of preparing the high specific surface area activated carbon according to the embodiment 2-1 (the method two) of the application are shown.

[0107] Figure 4 The N2-77K adsorption-desorption curve (left) and the pore size distribution (right) of the high specific surface area activated carbon prepared by the method two in the embodiment 2-3 of the application are shown.

[0108] Figure 5N2-77K adsorption-desorption curves (left) and pore size distribution (right) of high specific surface area activated carbon prepared according to Example 2-4 (Method 2) of the present application are shown.

[0109] Figure 6 N2-77K adsorption-desorption curves (left) and pore size distribution (right) of high specific surface area activated carbon prepared according to Example 2-5 (Method 2) of the present application are shown.

[0110] Figure 7 N2-77K adsorption-desorption curves (left) and pore size distribution (right) of high specific surface area activated carbon prepared according to Example 2-6 (Method 2) of the present application are shown.

[0111] Figure 8 N2-77K adsorption-desorption curves (left) and pore size distribution (right) of high specific surface area activated carbon prepared according to Example 3-1 (Method 3) of the present application are shown.

[0112] Figure 9 N2-77K adsorption-desorption curves (left) and pore size distribution (right) of high specific surface area activated carbon prepared according to Example 3-2 (Method 3) of the present application are shown.

[0113] Figure 10 N2-77K adsorption-desorption curves (left) and pore size distribution (right) of high specific surface area activated carbon prepared according to Comparative Example 1 are shown.

[0114] Figure 11 N2-77K adsorption-desorption curves (left) and pore size distribution (right) of activated carbon prepared according to Comparative Example 2 are shown.

[0115] Figure 12 H2 adsorption capacity of high specific surface area activated carbon prepared from raffinate according to Example 3-1 (Method 3) of the present application is shown.

[0116] Figure 13 H2 adsorption capacity of high specific surface area activated carbon prepared from raffinate according to Example 3-2 (Method 3) of the present application is shown.

[0117] Figure 14 H2 adsorption capacity of high specific surface area activated carbon prepared from coconut shells according to Comparative Example 1 of the prior art is shown. DETAILED DESCRIPTION

[0118] The present application is described in detail in the specification of the specific embodiments, those skilled in the art should realize that the following embodiments are exemplary and cannot be understood as a limitation of the present application, and those skilled in the art can make several improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application. The beneficial effects of the present application are specifically illustrated by the following examples.

[0119] Unless otherwise specified, the instruments used in the present application are conventional instruments, and the reagents used are conventional reagents.

[0120] Coal liquefied pitch: from Shenhua Ordos coal-to-oil branch, the raffinate in the coal liquefied pitch is about 50wt% of the coal liquefied pitch

[0121] Washing oil: from the National Energy Group Coal Coking Company, the washing oil used in the following examples has the following parameters:

[0122] Density at 20℃ is not more than 1.070g / cm 3 ;

[0123] Moisture is not more than 1.0%(mass fraction);

[0124] Distillation range: distillation rate at 210℃ is not higher than 3%(volume fraction), distillation rate at 300℃ is not lower than 90%(volume fraction);

[0125] Chlorine content is not more than 20mg / L;

[0126] Ash content is not more than 0.1%(mass fraction);

[0127] Acid value is not more than 0.5mgKOH / g;

[0128] Phenol content is not more than 0.5%(volume fraction).

[0129] Examples

[0130] Example 1-1: Preparation of high specific surface area activated carbon (Method 1)

[0131] Step 1:

[0132] The 320℃ coal liquefied pitch (the temperature is preferably between 280℃-320℃) from the coal liquefied vacuum tower is mixed with the 140℃ washing oil (the temperature is preferably between 120℃-140℃) at a volume ratio of 3:1, and then enters the extraction tank, and keeps stirring under normal pressure, and after stopping stirring, it is placed for 30min, and the raffinate is obtained by centrifugal solid-liquid separation and spray drying solvent recovery, wherein the content of pitch in the separated raffinate is about 1wt%;

[0133] Step 2:

[0134] Take 2 g of the residue and place it in a glass tube. Continuously pass ozone into the tube for 2 h at room temperature to pre-oxidize the material, obtaining activated carbon raw material;

[0135] Step 3:

[0136] The pre-oxidized activated carbon raw material is subjected to alkali activation. The alkali and activated carbon raw material are mixed uniformly in a ball mill, and the mixture is placed in a tube furnace under a nitrogen protective atmosphere. The temperature is raised from room temperature to 600°C at a rate of 5°C / min, maintained at 600°C for 1 h, then raised from 600°C to 800°C at a rate of 5°C / min, maintained at 800°C for 1 h, and then naturally cooled to room temperature. The prepared solid is added to distilled water, stirred for about 30 min, filtered, and a small amount of dilute hydrochloric acid is added to the solid to wash to pH = 2 (concentration about 2 mol / L) to remove residual alkali or other impurities. The solid is washed with distilled water three times until neutral, and then dried at 100°C for 10 h to obtain activated carbon with high specific surface area.

[0137] The activated carbon with high specific surface area is prepared in the same way as in Example 1-1, and the parameters of each example are listed in Table 1.

[0138] Table 1

[0139]

[0140] Example 2-1: Preparation of activated carbon with high specific surface area (Method 2)

[0141] Step 1:

[0142] The 320°C coal liquefaction pitch (temperature preferably between 280°C and 320°C) from the coal liquefaction vacuum tower is mixed with 140°C wash oil (temperature preferably between 120°C and 140°C) at a volume ratio of 3:1, and then enters an extraction tank. The mixture is continuously stirred at atmospheric pressure, and after stirring is stopped, it is left to stand for 30 min. The residue is obtained by centrifugal solid-liquid separation and spray drying solvent recovery. The content of pitch-like substances in the separated residue is about 1 wt%;

[0143] Step 2:

[0144] The raffinate was weighed according to the amount shown in Table 2, and then subjected to alkaline activation. The potassium hydroxide and the raffinate were mixed uniformly in a ball mill (dry grinding, or the potassium hydroxide can be dissolved in water in advance, and the raffinate was immersed in the potassium hydroxide solution for 4 h, and then dried in an oven at 100°C). The mixture was placed in a tube furnace, and then heated from room temperature to 600°C at a rate of 5°C / min under a nitrogen atmosphere. The temperature was maintained at 600°C for 1 h, and then heated from 600°C to 800°C at a rate of 5°C / min. The temperature was maintained at 800°C for 1 h, and then naturally cooled to room temperature. The obtained solid was added to distilled water, stirred for about 30 min, and then filtered. A small amount of dilute hydrochloric acid was added to the solid to wash to pH = 2 (concentration of about 2 mol / L), so as to remove residual alkali or other impurities. The solid was washed with distilled water until neutral for 3 times, and then dried at 100°C to obtain the high specific surface area activated carbon.

[0145] The SEM images of the raffinate before alkaline activation and the SEM images of the raffinate after alkaline activation in the preparation of the high specific surface area activated carbon according to Example 2-1 are shown in Figure 3 .

[0146] The high specific surface area activated carbon was prepared by the same method as in Example 2-1, and the parameters of each example are listed in Table 2.

[0147] Table 2

[0148]

[0149] Example 3-1: Preparation of high specific surface area activated carbon (Method 3)

[0150] Step 1:

[0151] 320°C coal liquefaction pitch (the temperature is preferably between 280°C and 320°C) from a coal liquefaction vacuum tower was mixed with 140°C wash oil (the temperature is preferably between 120°C and 140°C) at a volume ratio of 3:1, and then introduced into an extraction tank. The mixture was continuously stirred under normal pressure, and then allowed to stand for 30 min after the stirring was stopped. The raffinate was obtained by centrifugal solid-liquid separation and spray drying solvent recovery. The content of pitch in the obtained raffinate was about 1 wt%;

[0152] Step 2:

[0153] 1) Take the amount of raffinate shown in Table 3, mix the raffinate with 30-40% hydrochloric acid at room temperature in a beaker, and stir to react, the mass ratio of hydrochloric acid solution to raffinate is (2-8):1; after the addition of hydrochloric acid solution is completed, the beaker is placed in an ultrasonic cleaner to speed up the reaction rate, the reaction time is 5-15 min, the hydrochloric acid reaction removes calcium hydroxide, sulfur-iron catalyst and other minerals in the coal liquefaction raffinate, the reaction washing temperature is 20-60°C, then solid-liquid separation is carried out to obtain hydrochloric acid insoluble;

[0154] 2) Collect the hydrochloric acid insoluble, wash the hydrochloric acid insoluble repeatedly with hydrochloric acid and water in filter paper, the washing temperature is 20-60°C, to remove the attachments in the insoluble, filter through the filter paper, and dry to obtain the activated carbon raw material, wherein the ash content is 8.31wt%;

[0155] Step 3:

[0156] The activated carbon raw material obtained by acid washing and ash removal is subjected to alkali activation, wherein the alkali and the activated carbon raw material are uniformly ground and mixed in a ball mill, 3g of the mixture is placed in a tube furnace, and the temperature is raised from room temperature to 600°C at a rate of 5°C / min under a nitrogen protective atmosphere, maintained at this temperature for 1h, and then raised from 600°C to 800°C at a rate of 5°C / min, maintained at 800°C for 1h, and naturally cooled to room temperature; the prepared solid is added to distilled water, stirred for about 30 min, filtered, a small amount of dilute hydrochloric acid is added to the solid to wash to pH=2 or so (concentration about 2mol / L) to remove residual alkali or other impurities, washed with distilled water for 3 times to neutral, and dried at 100°C to obtain high specific surface area activated carbon.

[0157] The high specific surface area activated carbon is prepared by the same method as in Example 3-1, and the parameters of each example are listed in Table 3.

[0158] Table 3

[0159]

[0160]

[0161] Compared with Method I and Method II, Method III increases the yield of high specific surface area activated carbon by at least 16% by first acid washing and ash removal of the raffinate, and then alkali activation, and the amount of alkali is reduced from 4:1 to 3.12:1.

[0162] Comparative Example 1: Preparation of activated carbon from coconut shell

[0163] Step 1:

[0164] The coconut shell is put into a carbonization furnace, the carbonization temperature is generally between 500-800℃, and the duration is 3-4 hours, to obtain a pretreated coconut shell carbonization material.

[0165] Step 2:

[0166] The pretreated coconut shell carbonization material obtained in step 1 is stirred to remove impurities and crushed to obtain a carbonization material.

[0167] Step 3:

[0168] The carbonization material is placed in an activation furnace, high-temperature water vapor is introduced, the flow rate of the high-temperature water vapor is controlled to be 4-5m 3 / h, the pressure is 3-4MPa, the temperature is 1000-1200℃, and the reaction time is 10-12h.

[0169] Step 4:

[0170] The mixture of fuel gas and water vapor is continuously introduced into the activation furnace, and after secondary activation, the finished product is obtained by physical and mechanical impurity removal and airflow crushing, with a yield of about 50%.

[0171] Comparative Example 2: Preparation of activated carbon by steam method

[0172] 1) The coal liquefaction pitch is extracted and separated according to the same steps as steps 1 and 2 in Example 3-1, and is acid-washed and deashed to obtain a carbon-rich product, and the following steps are different.

[0173] 2) The carbon-rich product is directly activated by steam, and the amount of steam is 1.5 times that of the carbon-rich product. The raw material is added to a vertical reactor, nitrogen is first introduced into the reactor to drive out the air therein, and after 30 minutes, heating is started to raise the temperature to 450℃ at a speed of 10℃ / min for carbonization; then water vapor is introduced for activation, and after 90 minutes of activation at 950℃, heating is stopped, the gas flow is switched to nitrogen, and the temperature is lowered to room temperature under nitrogen protection. The activated carbon is vacuum dried at 120℃ for 8 hours, and the yield of activated carbon is 45%.

[0174] Test Example 1 N2-77K adsorption-desorption isotherm test

[0175] About 120mg of high specific surface area activated carbon is vacuum degassed at 200℃ for 6h, and the nitrogen adsorption isotherm of the high specific surface area activated carbon is determined at 77K using the American Micromeritics Extended Surface Area and Pore Size Analyzer ASAP 2460. The specific surface area (BET), pore volume, and pore diameter are calculated by Microactive software.

[0176] The N2-77K adsorption-desorption curve and pore size distribution of the activated carbon prepared in Examples 1-2, 1-3, 2-3, 2-4, 2-5, 2-6, 3-1, 3-2, Comparative Example 1, and Comparative Example 2 are shown in Figure 1 ,Figure 2 、 Figure 4 、 Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 and Figure 11 .

[0177] The BET, pore volume, and pore diameter parameters of the high specific surface area activated carbon prepared by the embodiments of the present application are shown in Table 4.

[0178] Table 4

[0179]

[0180]

[0181] As can be seen from Table 4, the activated carbon prepared according to the method one, the method two and the method three of the present application all have very high specific surface area, and the pore size distribution of the activated carbon is relatively concentrated, mainly distributed in the micropore region, compared with the activated carbon prepared from coconut shell (Comparative Example 1) and the activated carbon prepared by the steam method (Comparative Example 2).

[0182] Taking into account both the specific surface area and the pore size distribution, the activated carbon prepared by the method three of the present application is more optimal.

[0183] Test Example 2 Hydrogen Adsorption Capacity Test

[0184] 120 mg of high specific surface area activated carbon was weighed, vacuum degassed at 200°C for 6h, and the hydrogen storage performance of the high specific surface area activated carbon, i.e., the adsorption capacity of H2, was determined at 77K and 1 bar using a Micromeritics (Shanghai) Instrument ASAP 2020plus full-automatic static physical adsorption instrument.

[0185] The H2 adsorption capacity of the high specific surface area activated carbon prepared according to the method of Example 3-1, 3-2, and Comparative Example 1 of the present application is shown in Figure 12 、 Figure 13 and Figure 14 .

[0186] The results show that the adsorption amount of H2 of the high specific surface area activated carbon prepared from coconut shell is low, about 1.67wt%, and the adsorption amount of H2 of the high specific surface area activated carbon prepared from the raffinate of the present application is very high, up to 2.90wt%, so the high specific surface area activated carbon prepared from the raffinate in the present application has more optimal H2 adsorption capacity.

Claims

1. A method for preparing activated carbon with high specific surface area, comprising the following steps: Step 1: separating pitch-like substances and raffinate from coal liquefaction pitch by washing oil extraction; Step 2: pre-oxidizing the raffinate obtained in Step 1 by ozone; Step 3: alkali-activating the raffinate obtained in Step 2. In Step 1, the volume-to-mass ratio of washing oil to coal liquefaction pitch used for extraction is 2.0:1-5.0:1; the content of pitch-like substances in the raffinate obtained after separation is 1wt%-6wt%. In Step 2, ozone is continuously introduced into the raffinate at room temperature for 1-3 hours. In Step 3, the alkali used for alkali-activation is potassium hydroxide or sodium hydroxide; the mass ratio of alkali to raffinate used for alkali-activation is 2:1-4:1; the alkali-activation conditions are as follows: after mixing the activated carbon raw material obtained in pre-oxidation with alkali, calcination is performed at a temperature of 550°C to 650°C, and then calcination is performed at a temperature of 750°C to 850°C, after which the calcination is completed, the obtained solid is naturally cooled to room temperature, the solid is added into water, stirred, washed with water, filtered, the pH value is adjusted to about 2 by using acid, and then washed with water until neutral, dried, and thus activated carbon with high specific surface area is obtained. The acid used for adjusting the pH value is dilute hydrochloric acid, and the mass ratio of dilute hydrochloric acid to raffinate is 0.550:1-0.650:

1. The alkali-activation is performed under inert gas protection. The pre-oxidized active carbon raw material is subjected to alkali activation to obtain high specific surface area active carbon with a specific surface area of 2000 m 2 / g to 3300 m 2 / g; Pore volume 1.0 cm 3 / g to 1.9 cm 3 / g; pore diameter to 77K, 1 bar H2uptake 1.65wt% - 2.90wt%.

2. The production method according to claim 1, wherein, 5. The method according to claim 1, wherein, in Step 1, the volume-to-mass ratio of washing oil to coal liquefaction pitch used for extraction is 2.5:1-4.0:1; the content of pitch-like substances in the raffinate obtained after separation is 1wt%-4wt%; in Step 2, ozone is continuously introduced into the raffinate at room temperature for 1.5-2.5 hours; in Step 3, the alkali used for alkali-activation is potassium hydroxide; the mass ratio of alkali to raffinate used for alkali-activation is 2.5:1-4:1; the mass ratio of dilute hydrochloric acid to raffinate is 0.590:1-0.610:

1.

6. A method for preparing activated carbon with high specific surface area, comprising the following steps: Step 1: separating pitch-like substances and raffinate from coal liquefaction pitch by washing oil extraction; Step 2: alkali-activating the raffinate obtained in Step 1. In Step 1, the volume-to-mass ratio of washing oil to coal liquefaction pitch used for extraction is 2.0:1-5.0:1; the content of pitch-like substances in the raffinate obtained after separation is 1wt%-6wt%.

3. The production method according to claim 1, wherein In Step 2, the alkali used for alkali-activation is potassium hydroxide or sodium hydroxide; the mass ratio of alkali to raffinate used for alkali-activation is 2:1-4:1; the alkali-activation conditions are as follows: after mixing the raffinate with alkali, calcination is performed at a temperature of 550°C to 650°C, and then calcination is performed at a temperature of 750°C to 850°C, after which the calcination is completed, the obtained solid is naturally cooled to room temperature, the solid is added into water, stirred, washed with water, filtered, the pH value is adjusted to about 2 by using acid, and then washed with water until neutral, dried, and thus activated carbon with high specific surface area is obtained. The acid used for adjusting the pH value is dilute hydrochloric acid, and the mass ratio of dilute hydrochloric acid to raffinate is 0.550:1-0.650:

1.

4. The production method according to claim 1, wherein The alkali-activation is performed under inert gas protection.

9. The method according to claim 6, wherein, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The residue obtained from the separation is directly subjected to base activation to obtain activated carbon with high specific surface area, which has a specific surface area of 2000 m 2 / g to 3300 m 2 / g; Pore volume 1.0 cm 3 / g to 1.9 cm 3 / g; pore diameter to 77K, 1 bar H2uptake 1.65wt% - 2.90wt%.

7. The production method according to claim 6, wherein ​ ​ ​ 8. The production method according to claim 6, wherein ​ ​ ​ ​ ​ ​ ​ In step 1, the volume-to-mass ratio of the washing oil to the coal liquefaction pitch is 2.5:1-4.0:1; the content of the pitch-like substance in the obtained raffinate is 1wt%-4wt%; In step 2, the alkali used for the alkali activation is potassium hydroxide; the mass ratio of the alkali to the raffinate is 2.5:1-4:1; the mass ratio of the dilute hydrochloric acid to the raffinate is 0.590:1-0.610:

1.

10. A method for preparing a high specific surface area activated carbon, comprising the following steps: Step 1: separating pitch-like substances in coal liquefaction pitch and raffinate by washing oil extraction; Step 2: acid washing and ash removal of the obtained raffinate; Step 3: The acid-washed and deashed raw material of activated carbon is subjected to alkali activation to obtain activated carbon with high specific surface area, and the specific surface area thereof is 2000 m 2 / g to 3300 m 2 / g; Pore volume 1.0 cm 3 / g to 1.9 cm 3 / g; pore diameter to 77 K, 1 bar, 1.65 wt% - 2.90 wt% H2adsorption.

11. The production method according to claim 10, wherein In step 1, the volume-to-mass ratio of the washing oil to the coal liquefaction pitch is 2.0:1-5.0:1; the content of the pitch-like substance in the obtained raffinate is 1wt%-6wt%.

12. The production method according to claim 10, wherein, In step 2, the ash content of the obtained activated carbon raw material after the acid washing and ash removal is 2wt%-9wt%; the acid used for the acid washing and ash removal is hydrochloric acid; the mass ratio of the acid to the raffinate is 2:1-4:

1.

13. The method of making according to claim 10, wherein, In step 3, the alkali used for the alkali activation is potassium hydroxide or sodium hydroxide; the mass ratio of the alkali to the raffinate is 2:1-4:1; the alkali activation conditions are as follows: after mixing the activated carbon raw material obtained after the acid washing and ash removal with the alkali, calcination is performed at a temperature of 550°C to 650°C, and then calcination is performed at a temperature of 750°C to 850°C, after which the calcination is completed, the obtained solid is naturally reduced to room temperature, added to water, stirred, washed with water, filtered, the pH value is adjusted to about 2 using an acid, and then washed with water until neutral, and dried to obtain a high specific surface area activated carbon; the acid used for the pH adjustment is dilute hydrochloric acid, and the mass ratio of the dilute hydrochloric acid to the raffinate is 0.550:1-0.650:1; the alkali activation is performed under inert gas protection.

14. The method according to claim 10, wherein, In step 1, the volume-to-mass ratio of the washing oil to the coal liquefaction pitch is 2.5:1-4.0:1; the content of the pitch-like substance in the obtained raffinate is 1wt%-4wt%; In step 2, the acid used for the acid washing and ash removal is dilute hydrochloric acid; the mass ratio of the acid to the raffinate is 2.5:1-3.5:1; In step 3, the alkali used for the alkali activation is potassium hydroxide; the mass ratio of the alkali to the raffinate is 2.5:1-4:1; the mass ratio of the dilute hydrochloric acid to the raffinate is 0.590:1-0.610:

1.

15. A high specific surface area activated carbon prepared according to the method of any one of claims 1-5, according to the method of any one of claims 6-9, or according to the method of any one of claims 10-14, having a specific surface area of 2000 m2 / g to 3300 m2 / g; a pore volume of 1.0 cm3 / g to 1.9 cm3 / g; and a pore diameter of 0.5 nm to 2.0 nm; and a H2 adsorption capacity of 1.65 wt% to 2.90 wt% at 77 K, 1 bar. 2 2 3 3 77 K, 1 bar conditions.​​​​​ 16. The high specific surface area activated carbon of claim 15 having a specific surface area of 2300 m2 / g to 3300 m2 / g; a pore volume of 1.3 cm3 / g to 2.0 cm3 / g; a pore diameter of 0.5 nm to 2.0 nm; and a H2 adsorption of 1.75 wt% to 2.90 wt% at 77 K, 1 bar. 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 2.0 cm 3 / g; a pore diameter of 0.5 nm to 2.0 nm; and a H2 adsorption of 1.75 wt% to 2.90 wt% at 77 K, 1 bar. / g to 2.0 cm 77 K, 1 bar conditions.

17. The high surface area activated carbon of claim 15 having a surface area of 2800 m 2 / g to 3300 m 2 / g; a pore volume of 1.3 cm 3 / g to 1.6 cm 3 / g; a pore diameter of to a H2 adsorption of 1.85 wt% - 2.90 wt% at 77 K, 1 bar.

18. Use of the high specific surface area activated carbon according to any one of claims 15-17 or prepared by the method according to any one of claims 1-14 as a hydrogen adsorption carbon source.

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