Preparation method and application of porous carbon / ceramic functional material for purification of voocs

Abstract

The present application relates to the preparation method and application of the porous carbon / ceramic functional material for purifying VOOCs in a site, wherein the preparation method uses attapulgite and biomass as raw materials, loads manganese and cerium active components through an impregnation method, and prepares the porous carbon / ceramic functional material for purifying VOOCs in a site through a mixing-granulating-drying-subsection calcining process.The prepared porous carbon / ceramic functional material can realize efficient purification of VOOCs at a lower temperature (50-250 DEG C), and effectively solves the problem of easy odor penetration in the VOOCs purification process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of site volatile odorous organic compounds (VOOCs) pollution treatment, and particularly relates to a preparation method of a porous carbon / ceramic functional material and application of the porous carbon / ceramic functional material in purifying site VOOCs. BACKGROUND

[0002] Volatile odorous organic compounds (VOOCs) released during excavation and repair of an odorous pollution site include hydrocarbons and easily volatile organic compounds containing sulfur, nitrogen, chlorine and oxygen, which not only have the environmental hazards of general VOCs, but also can cause olfactory irritation at a low concentration (ppb) and are a typical environmental hazard. During repair of an odorous pollution site, odorous organic pollutants released from the site are generally collected under a canopy, transported to a purification reactor under negative pressure, and removed. Research on purification technology thereof has been a widely concerned hotspot.

[0003] The key to VOOCs purification technology is a purification functional material. Research reports show that attapulgite can be used as an adsorption / catalyst carrier to prepare a purification functional material, but the purification efficiency thereof is poor at a low temperature (50-250 DEG C), and the problem of odorous penetration cannot be solved. Studies show that carbon-based functional materials have a large specific surface area and rich pore structure, and can improve the purification efficiency of the functional material through adsorption, but whether the problem of odorous penetration can be solved has not been reported. Attapulgite and biochar are used as carriers to load active components, and a new type of carbon / ceramic functional material with high purification efficiency for site VOOCs at a low temperature (50-250 DEG C) and effectively solving the problem of odorous penetration can be prepared, but relevant research has not been reported. SUMMARY

[0004] The present application aims to provide a preparation method of a porous carbon / ceramic functional material for purifying site VOOCs and application of the porous carbon / ceramic functional material. The preparation method comprises the following steps: mixing biomass and attapulgite, loading manganese and cerium double active components by impregnation, and preparing the porous carbon / ceramic functional material through a granulation-drying-calcination process. The functional material has a compressive strength of 250-350 N, an abrasion resistance of 90%-97%, high purification efficiency for site VOOCs at 200-250 DEG C, a removal rate of >99%, no odor of tail gas after purification according to a three-point comparison odor bag method (GB / T 14675-93), and can effectively avoid odorous penetration.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] The application relates to a preparation method of porous carbon / ceramic functional materials for purifying VOOCs in a site, wherein palygorskite and biomass are used as raw materials, manganese and cerium active components are loaded through an impregnation method, and the porous carbon / ceramic functional materials with certain mechanical strength and high efficiency in purifying VOOCs in a site are prepared through a mixing-granulating-drying-subsection calcining process.

[0007] The subsection calcining process is as follows: first, calcining at a calcining temperature of 300-500 DEG C for 30-90 min in an N2 atmosphere, and then, calcining at a calcining temperature of 700-900 DEG C for 30-90 min.

[0008] The mass percentage of each component of the raw materials is as follows: palygorskite 40-60 wt%, biomass 40-60 wt%, and the total loading amount of manganese and cerium is 5-15 wt%, wherein the total loading amount of manganese and cerium refers to the percentage of the total mass of the added manganese and cerium in the total mass of the functional materials; the molar ratio of manganese / cerium is 1:1-9:1; the biomass includes at least one of agricultural solid waste source biomass and wood straws, and the agricultural solid waste source biomass is at least one of corn straws, wheat straws, rice straws, sugarcane residues, cotton straws and the like; the manganese salt includes at least one of manganese chloride, manganese nitrate, manganese sulfate and potassium permanganate; and the cerium salt includes at least one of cerium chloride, cerium nitrate, cerium sulfate and cerous sulfate.

[0009] The particle size of the palygorskite and the biomass is 150-450 mu m; preferably, the total loading amount of manganese and cerium is 6-10 wt%.

[0010] The specific steps of the preparation method of the porous carbon / ceramic functional materials for purifying VOOCs in a site are as follows:

[0011] Step 1, mixing: the palygorskite and the biomass are crushed through a 40-80 mesh sieve, the palygorskite and the biomass are weighed and uniformly mixed, and then the mixture is added into a mixed solution of manganese salt and cerium salt, stirred for 30-90 min, and dried at 60-100 DEG C until constant weight.

[0012] Step 2, granulating: the material obtained in step 1 is placed in a disc granulator, and granulated at a rotating speed of 30-80 r / min to obtain material balls with a diameter of 5-30 mm;

[0013] Step 3, drying: the material balls prepared in step 2 are dried at 60-100 DEG C for 6-12 h;

[0014] Step 4, subsection calcining: the temperature is raised to 300-500 DEG C at a rate of 5-10 DEG C / min, the dried material balls are calcined in an N2 atmosphere for 30-90 min, the temperature is continuously raised to 700-900 DEG C at a rate of 5-10 DEG C / min, and the material balls are calcined in an N2 atmosphere for 30-90 min to obtain the porous carbon / ceramic functional materials.

[0015] The application also protects the porous carbon / ceramic functional material for purifying site VOOCs obtained by the above preparation method.

[0016] The application conditions of the above porous carbon / ceramic functional material for purifying site VOOCs are as follows: the site VOOCs are collected by a shed, and are transported to a purification reactor by negative pressure for removal, the reaction temperature is 50-250 DEG C, the VOOCs concentration is 50-500 ppm, the O2 content is 5-30%, and the mass space velocity is 3600-72000 mL3600-72000 mL(g -1 ·h -1 ). The residual VOOCs in the tail gas is detected by gas chromatography, and the removal rate of VOOCs is > 99% under the condition of 200-250 DEG C; the odor intensity of the tail gas after purification is determined according to the three-point comparison method (GB / T 14675-93), and the odor intensity is odorless, which can effectively avoid odor penetration.

[0017] The site VOOCs include hydrocarbons and volatile organic matters containing sulfur, nitrogen, chlorine and oxygen elements, such as toluene, methyl mercaptan, methylamine and trichloroethylene.

[0018] Compared with the prior art, the application has the following beneficial effects:

[0019] Compared with the commercial vanadium-tungsten-titanium catalyst, the porous carbon / ceramic functional material prepared by the application has higher purification efficiency, and the tail gas after purification is odorless, which can effectively avoid odor penetration (see Table 1).

[0020] Table 1 Comparison results of performance indexes of the porous carbon / ceramic functional material

[0021]

[0022] Experimental conditions: the reaction temperature is 250 DEG C, the concentration of the representative compound of the hydrocarbon site VOOCs is 60 ppm, the O2 content is 10%, and the mass space velocity is 36000 mL(g -1 ·h -1 ).

[0023] The application uses attapulgite as a binder, simultaneously adds biomass and loads manganese and cerium active components, realizes adsorption and thermal catalysis coupling after two-stage calcination, obtains a functional material for purifying site VOOCs, makes the tail gas after purification odorless, and solves the problem of odor penetration in the process of treating site VOOCs by general technology. The functional material obtained by the application has good anti-penetration effect on odor.

[0024] The functional material obtained by the present application can obtain high purification efficiency through two-stage roasting, and effectively solves the problem of odor penetration in the purification process of VOCs in the field by combining the purification efficiency with the odor intensity of the tail gas after purification. In the past, the purification of pollutants only focused on removal rate, but high removal rate may still have odor, and the problem of odor penetration cannot be ignored or solved. DETAILED DESCRIPTION

[0025] In order to better understand the content of the present application, the present application will be further described below in combination with embodiments, but the examples do not limit the protection scope of the present application.

[0026] Example 1

[0027] (1) The porous carbon / ceramic functional material (hereinafter referred to as functional material or porous carbon / ceramic functional material) for purifying VOCs in the field, the preparation steps of the functional material are as follows:

[0028] Step 1, mixing: the attapulgite and biomass are crushed through a 60-mesh sieve, in this embodiment, the biomass is corn straw, 50wt% attapulgite and 50wt% corn straw are weighed and mixed uniformly, and then added to a mixed solution of manganese nitrate and cerium nitrate with a molar ratio of 1.5:1, stirred for 60 min, and dried at 80°C until constant weight. The total loading amount of manganese and cerium is 10wt%.

[0029] Step 2, granulation: the material obtained in step 1 is placed in a disc granulator and rotated at a speed of 50r / min to obtain material balls with a diameter of 8mm;

[0030] Step 3, drying: the material balls prepared in step 2 are dried at 80°C for 8h;

[0031] Step 4, section roasting: the dried material balls are roasted in N2 atmosphere at a rate of 10°C / min to 450°C for 60min, and then roasted in N2 atmosphere at a rate of 10°C / min to 800°C for 60min to obtain the porous carbon / ceramic functional material.

[0032] (2) Purification performance of the porous carbon / ceramic functional material for VOCs in the field

[0033] The experimental conditions for evaluating the performance of the porous carbon / ceramic functional material in purifying toluene, a representative compound of VOCs in the field, are as follows: the VOCs diffused in the field are collected by a canopy, and then transported to the purification reactor under negative pressure, the reaction temperature is 50-250°C, the toluene concentration is 60ppm, the O2 content is 10%, and the mass space velocity is 36000mL(g -1 ·h -1). The content of toluene in the tail gas after reaction was detected by gas chromatography, and the removal rate of toluene was calculated; the odor intensity of the tail gas was determined according to the Three-Point Comparative Odor Bag Method (GB / T 14675-93); the pressure strength and wear strength of the porous carbon / ceramic functional material were detected by a pressure strength tester and a wear strength tester, respectively, and the results are shown in Table 2.

[0034] Table 2 Removal rate of toluene, odor intensity of tail gas, and pressure strength and wear strength values of functional materials

[0035]

[0036] Example 2

[0037] (1) The porous carbon / ceramic functional material for purifying VOOCs in the field of the present example has the same raw materials and preparation process as in Example 1, except that the mixing conditions in the present example are as follows: 40wt% of attapulgite and 60wt% of corn straw are weighed and mixed uniformly.

[0038] (2) Purification performance of the porous carbon / ceramic functional material for VOOCs in the field

[0039] The experimental conditions for evaluating the performance of the porous carbon / ceramic functional material in purifying representative compounds of VOOCs in the sulfur-containing field are as follows: the VOOCs diffused in the field are collected by a canopy, and are transported to the purification reactor under negative pressure, the reaction temperature is 50-250℃, the concentration of methyl mercaptan is 60ppm, the O2 content is 10%, and the mass space velocity is 36000mL(g -1 ·h -1 ). The content of methyl mercaptan in the tail gas after reaction is detected by gas chromatography, and the removal rate of methyl mercaptan is calculated; the odor intensity of the tail gas is determined according to the Three-Point Comparative Odor Bag Method (GB / T 14675-93); the pressure strength and wear strength of the porous carbon / ceramic functional material are detected by a pressure strength tester and a wear strength tester, respectively, and the results are shown in Table 3.

[0040] Table 3 Removal rate of methyl mercaptan, odor intensity of tail gas, and pressure strength and wear strength values of functional materials

[0041]

[0042] Example 3

[0043] The porous carbon / ceramic functional material for purifying VOOCs in the field of the present example has the same preparation process as in Example 1, except that the mixing conditions in the present example are as follows: attapulgite and corn straw are weighed and mixed uniformly, and are added to a mixed solution of manganese sulfate and cerium nitrate with a molar ratio of manganese to cerium of 4:1, and the total loading amount of manganese and cerium is 8wt%.

[0044] (2) Purification performance of the porous carbon / ceramic functional material for VOOCs in the field

[0045] The experimental conditions for evaluating the performance of the porous carbon / ceramic functional material in purifying the representative compound methylamine of the nitrogen-containing site VOCs are as follows: the site VOCs diffused are collected by a canopy, and are transported to the purification reactor under negative pressure, the reaction temperature is 50-250℃, the concentration of methylamine is 60ppm, the O2 content is 10%, and the mass space velocity is 36000mL(g -1 ·h -1 ). The content of methylamine in the tail gas after the reaction is detected by gas chromatography, and the removal rate of methylamine is calculated; the odor intensity is determined according to the Three-Point Comparative Odor Bag Method (GB / T 14675-93); and the compression strength and abrasion resistance of the porous carbon / ceramic functional material are detected by a compression strength tester and an abrasion resistance tester, respectively. The results are shown in Table 4.

[0046] Table 4 Removal rate of functional material to methylamine, odor intensity of tail gas, and compression strength and abrasion resistance value

[0047]

[0048] Example 4

[0049] The porous carbon / ceramic functional material for purifying the site VOCs in this example is prepared by the same raw materials and process as in Example 1, except that the calcination conditions are as follows: the temperature is programmed to rise to 400℃ at a rate of 10℃ / min, the dried material is calcined in N2 atmosphere for 60min, the temperature is programmed to rise to 750℃ at a rate of 10℃ / min, and the material is calcined in N2 atmosphere for 60min, to obtain the porous carbon / ceramic functional material.

[0050] (2) Purification performance of the porous carbon / ceramic functional material to the site VOCs

[0051] The experimental conditions for evaluating the performance of the porous carbon / ceramic functional material in purifying the representative compound trichloroethylene of the chlorine-containing site VOCs are as follows: the site VOCs diffused are collected by a canopy, and are transported to the purification reactor under negative pressure, the reaction temperature is 50-250℃, the concentration of trichloroethylene is 60ppm, the O2 content is 10%, and the mass space velocity is 36000mL(g -1 ·h -1 ). The content of trichloroethylene in the tail gas after the reaction is detected by gas chromatography, and the removal rate of trichloroethylene is calculated; the odor intensity is determined according to the Three-Point Comparative Odor Bag Method (GB / T 14675-93); and the compression strength and abrasion resistance of the porous carbon / ceramic functional material are detected by a compression strength tester and an abrasion resistance tester, respectively. The results are shown in Table 5.

[0052] Table 5 Removal rate of functional material to trichloroethylene, odor intensity of tail gas, and compression strength and abrasion resistance value

[0053]

[0054] Comparative Example 1

[0055] Only the biomass, manganese salt and cerium salt in Example 1 of the present application were added, and the mixing, granulation, drying and staged calcination conditions of Example 1 were followed.

[0056] Comparative Example 2

[0057] Only the attapulgite and biomass in Example 1 of the present application were added, and the mixing, granulation, drying and staged calcination conditions of Example 1 were followed.

[0058] Comparative Example 3

[0059] Only the attapulgite, manganese salt and cerium salt in Example 1 of the present application were added, and the mixing, granulation, drying and staged calcination conditions of Example 1 were followed.

[0060] Comparative Example 4

[0061] The mixing, granulation and drying conditions of Example 1 were followed, except that the staged calcination was not performed, and the dried material was directly programmed to 400°C at a rate of 10°C / min, and the dried material was calcined in a N2atmosphere for 120 min to obtain the functional material.

[0062] Comparative Example 5

[0063] The mixing, granulation and drying conditions of Example 1 were followed, except that the staged calcination was not performed, and the dried material was directly programmed to 800°C at a rate of 10°C / min, and the dried material was calcined in a N2atmosphere for 120 min to obtain the functional material.

[0064] Comparative Example 6

[0065] Only one kind of commercial granular activated carbon was used.

[0066] Comparative Example 7

[0067] Only one kind of commercial vanadium-tungsten-titanium catalyst was used.

[0068] The functional materials obtained in Comparative Examples 1-7 were all subjected to the purification experiment conditions of Example 1, and the results of the removal rate of toluene are shown in Table 6, the results of the odor intensity of the tail gas are shown in Table 7, and the results of the intensity numerical values are shown in Table 8.

[0069] Table 6 Comparison Table of Comparative Examples and Example 1 for Toluene Removal Rate

[0070]

[0071] Table 7 Comparison Table of Comparative Examples and Example 1 for Odor Intensity of Tail Gas

[0072]

[0073] Sensory description: 0-no odor, 1-odor is questionable, 2-weak odor but can determine what odor, 3-odor is noticeable, 4-strong odor is perceived.

[0074] Table 8 Comparison table of strength values of comparative examples and example 1

[0075]

[0076] The comparison of the above table results shows that the porous carbon / ceramic functional material prepared in the application has higher mechanical strength, and the removal rate of the site VOOCs in the range of 200-250 DEG C reaches more than 99%, has excellent removal rate, the odor intensity of the tail gas after purification is 0, and the penetration of malodor can be effectively avoided.

[0077] Example 5-8

[0078] The raw materials and preparation process of the example are the same as those of example 1, except that different kinds of biomass are used as raw materials in the example, i.e., rice straw, sugarcane residue, cotton stalk and poplar wood.

[0079] The functional material of the example is subjected to the purification experiment under the experimental conditions of example 1, and the experimental results show that the compressive strength is in the range of 250-350 N, the wear resistance is 90%-97%, high-efficiency purification of the site VOOCs under the condition of 200-250 DEG C is realized, the odor intensity of the tail gas after purification is 0, and the penetration of malodor can be effectively avoided.

[0080] In the application, attapulgite is used as an inexpensive raw material to prepare an adsorption / catalyst carrier and simultaneously as a binder for granulation and molding of the particulate catalyst, biomass has a large specific surface area and abundant pore structure, is used as a functional material for adsorption and purification of the site VOOCs, and the loading of active components can improve the purification efficiency through catalytic oxidation.

[0081] The unmentioned parts of the application are applicable to the prior art.

Claims

1. A method for preparing a porous carbon / ceramic functional material for purifying VOOCs in a treatment site, characterized in that, The preparation method uses attapulgite clay and biomass as raw materials, loads manganese and cerium active components by impregnation, and prepares porous carbon / ceramic functional materials for purifying VOOCs in the site through a process of mixing, granulation, drying and segmented calcination. The mass percentages of each component of the raw materials are as follows: attapulgite 40-60 wt%, biomass 40-60 wt%, and total manganese and cerium loading 5-15 wt%; wherein the manganese / cerium molar ratio is 1:1 to 9:

1. The segmented calcination process is as follows: first, calcining at a calcination temperature of 300~500℃ for 30~90 minutes in a N2 atmosphere, and then calcining at a calcination temperature of 700~900℃ for 30~90 minutes. The material is used to purify VOOCs in the site. Gas chromatography is used to detect residual VOOCs in the reaction. Under the condition of 200~250℃, the removal rate of VOOCs is >99%, and the odor intensity level of the exhaust gas is 0.

2. The preparation method according to claim 1, characterized in that, The biomass includes agricultural solid waste biomass and woody straw, wherein the agricultural solid waste biomass is at least one of corn straw, wheat straw, rice straw, sugarcane bagasse, and cotton straw.

3. The preparation method according to claim 1, characterized in that, The particle size of the attapulgite soil and biomass is 150~450μm; the total loading of manganese and cerium is 6~10wt%.

4. The preparation method according to claim 1, characterized in that, The specific steps of the preparation method are as follows: Step 1, Mixing: Crush attapulgite and biomass through a 40-80 mesh sieve, weigh out the attapulgite and biomass and mix them evenly, then add them to a mixed solution of manganese salt and cerium salt, stir for 30-90 min, and dry at 60-100℃ to constant weight. Step 2, Granulation: Place the material obtained in Step 1 into a disc granulator and granulate it at a speed of 30~80 r / min to obtain pellets with a diameter of 5~30 mm; Step 3, Drying: Dry the pellets prepared in step 2 at 60~100℃ for 6~12 h; Step 4, Segmented calcination: Increase the temperature to 300-500℃ at a rate of 5-10℃ / min. o C. The dried material balls are calcined in N2 atmosphere for 30-90 min, and then the temperature is increased to 700-900℃ at a rate of 5-10℃ / min. The calcined material is then calcined in N2 atmosphere for 30-90 min to obtain porous carbon / ceramic functional material for purifying VOOCs in the site.

5. The preparation method according to claim 4, characterized in that, The manganese salt includes at least one of manganese chloride, manganese nitrate, manganese sulfate, and potassium permanganate; the cerium salt includes at least one of cerium chloride, cerium nitrate, cerium sulfate, and cerium sulfate.

6. A porous carbon / ceramic functional material for purifying VOOCs in a treatment environment, obtained by the preparation method according to any one of claims 1 to 5, characterized in that, The porous carbon / ceramic functional material for VOOCs purification sites has a compressive strength of 250~350 N and an abrasion resistance of 90%~97%.

7. The application of the porous carbon / ceramic functional material for purifying VOOCs in a site as described in claim 6, characterized in that, VOOCs escaping from the site are collected under a canopy and transported under negative pressure to a purification reactor for removal. The reaction temperature is 50–250℃, the VOOCs concentration is 50–500 ppm, the O2 volume content is 5–30%, and the mass hourly space velocity is 3600–72000 mL (g). -1 •h -1 ).

8. The application according to claim 7, characterized in that, The site VOOCs include hydrocarbons and volatile organic compounds containing sulfur, nitrogen, chlorine and oxygen elements, including at least one of toluene, methanethiol, methylamine and trichloroethylene.

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