Preparation method and application of resin-based carbon spheres

Abstract

The application discloses a preparation method and application of resin-based carbon spheres and belongs to the technical field of adsorbing materials. Raw materials containing resin spheres are sequentially subjected to pre-oxidation treatment and carbonization treatment to obtain the resin-based carbon spheres; the pre-oxidation treatment process is selected from wet air oxidation; and the diameter of the resin spheres is 100 microns to 2000 microns. The prepared high-strength resin-based carbon spheres are applied to adsorb organic pollutants in wastewater, and have good adsorption and desorption effects.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of adsorbing materials, in particular to a method for preparing carbon microspheres by using high-strength resin microspheres as a precursor. BACKGROUND

[0002] As an excellent adsorbent, carbon material has a large specific surface, rich pore structure and excellent chemical stability, and is often used as a high-efficiency adsorbent in environmental pollution treatment. However, traditional activated carbon material often has poor mechanical properties and is easy to fall off, and has a great bottleneck in the application process of catalysis and the environment.

[0003] According to the different shapes, the activated carbon material can be divided into powder activated carbon, granular activated carbon, columnar activated carbon, honeycomb activated carbon, spherical activated carbon and activated carbon fiber. Spherical activated carbon has the characteristics of smooth surface, high mechanical strength, easy-to-control pore size distribution, small fluid resistance and good physiological compatibility, and has attracted widespread attention from researchers. According to the different raw materials, the spherical activated carbon can be divided into coal-based spherical activated carbon, pitch-based spherical activated carbon and high polymer-based spherical activated carbon.

[0004] Coal-based activated carbon is widely used in national defense, food safety, medicine and environmental governance, and has good chemical stability and adsorption performance, but has the defects of high ash content, difficulty in forming a ball, low mechanical strength and the like in the preparation process; pitch-based activated carbon has the advantages of wide raw material sources, low price, large specific surface, low ash content, good sphericity and high mechanical strength, and is an ideal activated carbon material. However, in the industrial scale-up process, there are problems such as relatively complex process, long gas phase oxidation time, high energy consumption and large pollution, and therefore the technical method needs to be further explored. High polymer-based spherical activated carbon has always been the focus of spherical activated carbon research, and polystyrene-divinylbenzene copolymer, phenolic resin, polyacrylonitrile, polyvinylidene chloride, polyvinyl alcohol and polyimide are relatively common precursors. High polymer resin-based carbon spheres have the advantages of high carbonization rate, easy pore formation and strong adsorption capacity.

[0005] High polymer resin-based carbon spheres are usually subjected to a pre-oxidation and carbonization process under high-temperature gas phase conditions, and a sulfonation process is also usually carried out by using sulfur trioxide gas for sulfonation treatment. The process is simple, but often has the problems of high energy consumption, serious pollution, high safety risk and the like. Therefore, it is of great significance to research and explore a cleaner and more efficient resin ball pretreatment, carbonization and post-treatment process.

[0006] The resin-based precursor can be a macroporous resin and a gel-type resin. The gel-type resin has a smaller pore size. In the existing pre-oxidation stage and sulfonation stage, the oxidizing agent and the sulfonating agent are difficult to reach the inside of the resin ball, which easily leads to problems such as adhesion of the carbonized ball in the later stage, small strength, and difficulty in maintaining the shape. SUMMARY

[0007] The present application mainly relates to a preparation method of a resin-based carbon ball, which is mainly prepared through pre-oxidation, sulfonation and carbonization. In the method, the pre-oxidation and sulfonation steps are both carried out by a high-temperature and high-pressure wet method, that is, under the conditions of high temperature (100℃-320℃) and high pressure (0.5MPa-8MPa), an oxidizing agent or a sulfonating agent is once or continuously introduced into a reactor containing resin balls, and the resin balls are allowed to react with the oxidizing agent or the sulfonating agent under the conditions for a period of time. The high-pressure wet pre-oxidation and sulfonation treatment can make the oxidizing agent and the sulfonating agent reach the inside of the gel-type resin ball, and has high universality for various types of resins. In addition, the process also has the advantages of cleanliness, small pollution, high safety and the like.

[0008] The method can be operated by using a batch kettle reactor or a fixed-bed continuous reactor. The kettle reactor is a completely closed system, the resin ball precursor is added at one time, and the oxidizing agent and the sulfonating agent can be added in batches. The fixed-bed continuous reactor is a non-completely closed system. After the resin balls are pre-filled in the continuous reactor and connected to the reaction system, the liquid oxidizing agent or the sulfonating agent is continuously injected into the reaction system by a liquid-phase booster pump, and the gaseous reactant (air or oxygen as the oxidizing agent) can be directly injected into the reaction system by adjusting the pressure to a suitable pressure by using a high-pressure gas cylinder and a pressure regulating valve.

[0009] After the resin balls are dried by the pre-oxidation-sulfonation process under the wet condition, high-temperature carbonization is carried out. The carbonization process mainly pyrolyzes the ring structure and the chain structure in the resin. After the processes such as cyclization, polycondensation and aromatization, a stable network structure is finally formed.

[0010] According to one aspect of the present application, a preparation method of a resin-based carbon ball is provided. Raw materials containing resin balls are sequentially subjected to pre-oxidation treatment and carbonization treatment to obtain the resin-based carbon ball. The pre-oxidation treatment process is selected from wet air oxidation.

[0011] The diameter of the resin ball is 100 microns to 2000 microns.

[0012] The resin ball described in the present application can be a resin ball that has not been used, or a resin ball that is recovered after use.

[0013] The wet air oxidation described in the present application refers to oxidation of the resin ball in a gas-water mixed phase with air or oxygen as the oxidizing agent under certain temperature and pressure.

[0014] Optionally, after the pre-oxidation treatment, a sulfonation treatment is performed, and then a carbonization treatment is performed.

[0015] Optionally, the pre-oxidation treatment is performed at a temperature of 100-320°C, a pressure of 0.5-8 MPa, and for a time of 1-24 h.

[0016] Optionally, the pre-oxidation treatment is performed at a temperature selected from 120°C, 140°C, 150°C, 180°C, 200°C, 200°C, 220°C, 250°C, 270°C, 280°C, 300°C, 310°C, or any value between any two of the above values; and a pressure selected from 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, or any value between any two of the above values.

[0017] Optionally, the sulfonation treatment is performed in an aqueous phase, and the sulfonation reagent is selected from at least one of sulfuric acid, sulfurous acid, or a persulfate salt.

[0018] The sulfonation treatment is performed at a temperature of 100-320°C, a pressure of 0.5-8 MPa, and for a time of 1-24 h.

[0019] Optionally, in the sulfonation treatment, the concentration of the aqueous sulfonation reagent is 0.5-5 mol / L, and the mass ratio of the aqueous sulfonation reagent to the dry weight of the resin to be sulfonated is 2:1-100:1.

[0020] Optionally, the sulfonation treatment is performed at a temperature selected from 120°C, 140°C, 150°C, 180°C, 200°C, 200°C, 220°C, 250°C, 270°C, 300°C, 310°C, or any value between any two of the above values; and a pressure selected from 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, or any value between any two of the above values.

[0021] Optionally, the carbonization treatment is preceded by drying at 80-120°C for 4-12 h.

[0022] The carbonization treatment is performed by calcination in a non-reactive atmosphere, and the carbonization treatment is performed by calcination in a staged heating mode, including a shaping stage and a carbonization stage.

[0023] Optionally, the drying temperature before the carbonization treatment is selected from 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or any value between any two of the above values.

[0024] Optionally, the baking temperature of the shaping stage is 240-400 DEG C, and the baking time is 2-20 h; the baking temperature of the carbonization stage is 600-1100 DEG C, and the baking time is 1-10 h.

[0025] Optionally, the baking temperature of the shaping stage is selected from 250 DEG C, 280 DEG C, 300 DEG C, 320 DEG C, 350 DEG C, 360 DEG C, 380 DEG C, 390 DEG C, or any value between any two of the above; the baking time of the shaping stage is selected from 4 h, 5 h, 6 h, 8 h, 10 h, 12 h, 15 h, 17 h, 19 h, or any value between any two of the above.

[0026] Optionally, the baking temperature of the carbonization stage is selected from 650 DEG C, 700 DEG C, 750 DEG C, 800 DEG C, 850 DEG C, 900 DEG C, 950 DEG C, or any value between any two of the above; the baking time of the carbonization stage is selected from 2 h, 3 h, 4 h, 5 h, 6 h, 8 h, 9 h, or any value between any two of the above.

[0027] According to one aspect of the present application, there is provided a resin-based carbon sphere prepared by the above preparation method, wherein the specific surface area of the resin-based carbon sphere is 600-1000 m 2 / g, and the pore volume is 0.3-0.6 cm 3 / g.

[0028] According to one aspect of the present application, there is provided a use of the resin-based carbon sphere prepared by the above preparation method in wastewater treatment; the adsorption rate of the resin-based carbon sphere to small-molecule acid pollutants is 85%-100% at room temperature.

[0029] In the present application, the reactor used for pre-oxidation treatment and sulfonation treatment can be a batch tank reactor or a fixed-bed continuous reactor.

[0030] In the pre-oxidation treatment process using a batch tank reactor, solid (resin sphere)-water-gas (oxygen) is sealed in a high-pressure resistant reactor in advance, and then heated or gradiently heated to a target temperature for oxidation reaction; the mixed volume ratio of water and resin sphere is in the range of 0.1-10; oxygen is used as the oxidant, wherein the volume of high-pressure oxygen in the batch tank reactor accounts for 0.2-0.6 of the total volume of the reactor, the oxygen pressure is in the range of 0.5 MPa-8 MPa, and the oxidation reaction temperature is 100 DEG C-320 DEG C.

[0031] In the sulfonation treatment process using a batch tank reactor, after adding a sulfonation reagent into the reactor, inert gas is injected into the sealed attachment to replace the oxygen-containing gas in the attachment, and then the inert gas is injected to a certain pressure (0.5 MPa-8 MPa) and heated to a target temperature for sulfonation reaction.

[0032] In the pre-oxidation treatment process using the fixed bed continuous reactor, the resin balls are fixed in the continuous reactor, and air and water are mixed in a certain volume ratio (calculated at standard conditions) and then introduced into the reactor to oxidize the resin fixed bed. Oxygen and water are continuously introduced into the reactor from the bottom inlet of the bed and discharged from the upper outlet of the bed during the reaction. The volume ratio of air and water is 1-1000, the oxygen pressure is 0.5-8 MPa, and the oxidation reaction temperature is 100-320°C.

[0033] In the sulfonation treatment process using the fixed bed continuous reactor, the oxygen-containing gas is turned off, and the prepared sulfonation reagent solution (concentration of 0.5-5 mol / L) is introduced into the continuous reactor at a certain flow rate (10-200 ml / h) under the condition of no gas or inert atmosphere. The reaction pressure is 0.5-8 MPa.

[0034] The beneficial effects of the present application include:

[0035] In the pre-oxidation treatment of the present application, wet air oxidation is used to pre-oxidize the resin balls under high temperature and high pressure conditions to construct a rich surface containing oxygen functional groups. The sulfonation treatment is also carried out under high temperature and high pressure conditions, which is beneficial to improve the sulfonation efficiency of the resin balls. The carbonization treatment uses the method of inert atmosphere stage high temperature calcination to obtain carbon balls with high strength, high specific surface area and good adsorption and regeneration performance. The prepared resin-based carbon balls are applied to adsorb organic pollutants in wastewater, and have good adsorption and desorption effect. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is a schematic diagram of the batch kettle reactor and the fixed bed continuous reactor.

[0037] Figure 2 It is a photograph of the commercial polystyrene resin balls.

[0038] Figure 3 It is a photograph of the resin-based carbon balls prepared in Example 1. DETAILED DESCRIPTION

[0039] The present application will be described in detail below in conjunction with examples, but the present application is not limited to these examples. Unless otherwise specified, the raw materials in the examples of the present application are purchased through commercial channels.

[0040] Among them, the commercial polystyrene resin balls are purchased from DuPont Company, P613 type.

[0041] Example 1

[0042] In a 500 ml titanium alloy reaction kettle, 50 g of commercial polystyrene resin balls with a particle size of about 1 mm (such as Figure 2The 50 g of polystyrene resin balls were loaded into a 500 ml titanium alloy reaction kettle and 200 ml of deionized water was added. After sealing, oxygen was injected into the reaction kettle through the gas inlet pipe to a pressure of 2 MPa, and the temperature was raised to 150°C. After reaching the reaction temperature, the reaction was carried out for 2 h. After taking out, drying was carried out in a 100°C oven for 6 h. The dried resin balls were first calcined at 300°C in a rotary atmosphere furnace under nitrogen protection for 5 h, and then further calcined at 600°C for 3 h to obtain resin-based carbon balls, which were named PSS-1.

[0043] Example 2

[0044] The same as Example 1, except that the temperature of the reaction kettle was raised to 200°C before starting the wet pre-oxidation reaction. The obtained resin-based carbon balls were named PSS-2.

[0045] Example 3

[0046] The same as Example 1, except that the temperature of the reaction kettle was raised to 240°C before starting the wet pre-oxidation reaction. The obtained resin-based carbon balls were named PSS-3.

[0047] Example 4

[0048] The same as Example 1, except that the temperature of the reaction kettle was raised to 280°C before starting the wet pre-oxidation reaction. The obtained resin-based carbon balls were named PSS-4.

[0049] Example 5

[0050] The 50 g of polystyrene resin balls were loaded into a 500 ml titanium alloy reaction kettle and 200 ml of deionized water was added. After sealing, oxygen was injected into the reaction kettle through the gas inlet pipe to a pressure of 2 MPa, and the temperature was raised to 240°C. After reaching the reaction temperature, the reaction was carried out for 2 h. After taking out, drying was carried out in a 100°C oven for 6 h. The dried resin balls were first calcined at 300°C in a rotary atmosphere furnace under nitrogen protection for 5 h, and then further calcined at 700°C for 3 h to obtain resin-based carbon balls, which were named PSS-5.

[0051] Example 6

[0052] The same as Example 5, except that the first calcination was at 300°C for 5 h, and then further calcination was carried out at 800°C for 3 h. The obtained resin-based carbon balls were named PSS-6.

[0053] Example 7

[0054] The same as Example 5, except that the first calcination was at 300°C for 5 h, and then further calcination was carried out at 900°C for 3 h. The obtained resin-based carbon balls were named PSS-7.

[0055] Example 8

[0056] The same as example 5, except that the resin-based carbon spheres obtained by first calcining at 300°C for 5h in a rotating atmosphere furnace and then further calcining at 1000°C for 3h are named PSS-8.

[0057] Example 9

[0058] The same as example 5, except that the resin-based carbon spheres obtained by first calcining at 300°C for 5h in a rotating atmosphere furnace and then further calcining at 1100°C for 3h are named PSS-9.

[0059] Example 10

[0060] A 500ml titanium alloy tubular reactor was loaded with 50g of commercial polystyrene resin spheres, and the reactor was sealed and connected to a wet oxidation reaction system. Air and water were injected into the reaction system, and the water filled the entire reaction system and was continuously injected into the reaction system at a flow rate of 100ml / h using a high-pressure liquid pump. The pressure of the reaction system was adjusted to 6MPa, and the air flow rate was adjusted to 100ml / min. The temperature was raised to 240°C, and the reaction was carried out for 2h after the reaction temperature was reached. The reacted sample was dried in a 100°C oven for 6h, and the dried resin spheres were calcined at 300°C for 5h in a rotating atmosphere furnace under nitrogen protection, and then further calcined at 700°C for 3h to obtain resin-based carbon spheres, which were named PSS-10.

[0061] Example 11

[0062] The same as example 10, except that the air flow rate was adjusted to 200ml / min, and the resin-based carbon spheres obtained were named PSS-11.

[0063] Example 12

[0064] The same as example 10, except that the air flow rate was adjusted to 300ml / min, and the resin-based carbon spheres obtained were named PSS-12.

[0065] Example 13

[0066] The same as example 10, except that the air flow rate was adjusted to 400ml / min, and the resin-based carbon spheres obtained were named PSS-13.

[0067] Example 14

[0068] The same as example 10, except that the air flow rate was adjusted to 500ml / min, and the resin-based carbon spheres obtained were named PSS-14.

[0069] Example 15

[0070] In a 500ml titanium alloy reactor, 50g of commercial polystyrene resin balls were loaded and 200ml of deionized water was added. After sealing, oxygen was injected into the reactor through the gas inlet pipe to a pressure of 2MPa, and the temperature was raised to 240°C. After reaching the reaction temperature, the reaction was carried out for 2h. After cooling and taking out, the resin balls were filtered and reloaded into the reactor. 200ml of 10wt% H2SO4 solution was added to the reactor, and nitrogen was injected to a pressure of 2MPa. The temperature was raised to 100°C, and after reaching the reaction temperature, the reaction was carried out for 2h. After cooling, the product was taken out and filtered, washed with water, and dried at 100°C. The dried resin balls were first calcined at 300°C for 5h in a rotary atmosphere furnace under nitrogen protection, and then further calcined at 700°C for 3h. The resin-based carbon balls obtained were named PSS-15.

[0071] Example 16

[0072] The same as example 15, except that the reaction temperature of the sulfonation stage after adding 10% H2SO4 solution was 120°C. The resin-based carbon balls obtained were named PSS-16.

[0073] Example 17

[0074] The same as example 15, except that the reaction temperature of the sulfonation stage after adding 10% H2SO4 solution was 150°C. The resin-based carbon balls obtained were named PSS-17.

[0075] Example 18

[0076] The same as example 15, except that the reaction temperature of the sulfonation stage after adding 10% H2SO4 solution was 180°C. The resin-based carbon balls obtained were named PSS-18.

[0077] Example 19

[0078] The same as example 15, except that the reaction temperature of the sulfonation stage after adding 10% H2SO4 solution was 200°C. The resin-based carbon balls obtained were named PSS-19.

[0079] The specific surface area and pore volume of the resin-based carbon balls prepared were measured:

[0080] Test instrument: Konata AUTOSORB IQ, test conditions: 300°C, 3h degassing pretreatment, N2 physical adsorption after treatment.

[0081] Table 1 Specific surface area and pore volume of resin-based carbon balls prepared in examples 1-14

[0082]

[0083]

[0084] From Table 1, it can be seen that the specific surface area of the carbon spheres prepared by the wet pre-oxidation method has reached 700 m 2 / g or more, and the reaction temperature in the wet pre-oxidation stage has a slight effect on the specific surface area and pore volume of the carbon spheres; the calcination temperature in the calcination stage has a greater effect on the specific surface area and pore volume, and with the increase of the calcination temperature, the specific surface area and pore volume of the obtained carbon spheres are both increased. In the pre-oxidation process using a continuous reactor, the air flow rate has a more obvious effect on the specific surface area and pore volume of the obtained carbon spheres, and with the increase of the air flow rate, the specific surface area and pore volume are both obviously increased.

[0085] Table 2: Specific surface area and carbonization yield of carbon spheres prepared in Examples 15-19

[0086]

[0087] From the comparison of the data in Table 2, it can be seen that the introduction of sulfonic acid groups can effectively improve the carbonization yield of the resin carbon spheres, and also helps to increase the specific surface area of the obtained carbon spheres. Compared with the traditional sulfonation process, the required concentration of the sulfonation reagent is lower, and the sulfonation effect is better. Among them:

[0088] Carbonization yield (%) = m t / m0*100%

[0089] m t : mass of carbon spheres after carbonization, g

[0090] m0: dry weight of carbon spheres before carbonization, g

[0091] Example 20

[0092] 1 g of PSS-12 prepared in Example 12 was weighed into 10 mL of 1000 mg / L acetic acid, propionic acid, n-butyric acid, ethanedioic acid, propanedioic acid, butanedioic acid, cis-butenedioic acid, trans-butenedioic acid, propenoic acid, isobutyric acid, and salicylic acid solutions with pH = 1, and the TOC values and TOC removal rates of the solutions before and after adsorption for 4 h were measured, as shown in Table 3. It can be seen that the prepared resin-based microspheres have excellent adsorption and removal capacity for various small-molecule organic acids. Among them:

[0093] TOC removal rate (%) = TOC0-TOC t / TOC0*100

[0094] TOC0is the total organic carbon content before adsorption, and TOC t is the total organic carbon content after adsorption for a period of time.

[0095] Table 3 Adsorption removal ability of PSS-18 carbon spheres to different small molecule acids

[0096]

[0097] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the preferred embodiments are disclosed above, the present application is not limited thereto. Any person skilled in the art can make some changes or modifications to the above disclosed technical contents without departing from the scope of the present application, and the equivalent embodiments are equivalent to the equivalent embodiments, which are within the scope of the technical solutions.

Claims

1. A method for preparing resin-based carbon spheres for adsorbing small molecule acid pollutants, characterized in that: The raw material containing resin balls is subjected to pre-oxidation treatment, sulfonation treatment, and carbonization treatment in sequence to obtain the resin-based carbon balls; the pre-oxidation treatment process is selected from wet air oxidation; The diameter of the resin ball is 100 microns to 2000 microns; The pre-oxidation treatment is performed at a temperature of 100° C. to 320° C., a pressure of 0.5 MPa to 8 MPa, and a time of 1 to 24 hours. The sulfonation treatment is carried out in an aqueous phase at a temperature of 100° C. to 320° C., a pressure of 0.5 MPa to 8 MPa, and a time of 1 to 24 hours.

2. The preparation method according to claim 1, characterized in that The sulfonating agent is at least one of sulfuric acid, sulfurous acid or persulfate.

3. The preparation method according to claim 1, characterized in that In the sulfonation treatment, the concentration of the sulfonation reagent aqueous solution is 0.5-5 mol / L, and the mass ratio of the sulfonation reagent aqueous solution to the dry weight of the resin to be sulfonated is 2:1-100:

1.

4. The preparation method according to claim 1, characterized in that The carbonization treatment is carried out by drying at 80-120° C. for 4-12 hours; The carbonization treatment is carried out by calcining in an inactive atmosphere; the carbonization treatment adopts a staged temperature increase method, including a forming stage and a carbonization stage.

5. The preparation method according to claim 4, characterized in that The calcination temperature of the forming stage is 240-400° C., and the calcination time is 2-20 hours; the calcination temperature of the carbonization stage is 600-1100° C., and the calcination time is 1-10 hours.

6. A resin-based carbon sphere prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The specific surface area of ​​the resin-based carbon spheres is 600-1000 m 2 / g, pore volume is 0.3~0.6cm 3 / g.

7. Use of resin-based carbon spheres prepared by the preparation method according to any one of claims 1 to 5 in adsorbing small molecule acid pollutants, characterized in that: The resin-based carbon spheres have an adsorption rate of 85% to 100% for small molecular acid pollutants at room temperature.

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