CN114590815A - Porous cordierite and preparation method and application thereof - Google Patents
Porous cordierite and preparation method and application thereof Download PDFInfo
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- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/26—Aluminium-containing silicates, i.e. silico-aluminates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/16—Alumino-silicates
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
- B01J20/28078—Pore diameter
- B01J20/28085—Pore diameter being more than 50 nm, i.e. macropores
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28054—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their surface properties or porosity
- B01J20/28095—Shape or type of pores, voids, channels, ducts
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- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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- C01P2006/16—Pore diameter
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/19—Oil-absorption capacity, e.g. DBP values
Abstract
The invention discloses porous cordierite which has the characteristics of high porosity, large pore diameter, high specific surface area and the like, so that the porous cordierite has a good grease adsorption effect and can be used in the field of oil stain treatment. Meanwhile, the invention also discloses a preparation method of the porous cordierite, the method adopts hydraulic alumina powder as an alumina source material, the hydraulic alumina powder can be used as a source of alumina and a binding agent without adding an additional binding agent, and the apparent porosity, the apparent pore size and the bulk density of the prepared porous cordierite powder are effectively controlled by controlling the size and the using amount of a pore-forming agent, the central particle size of the finally prepared porous cordierite powder and the like, so that the prepared porous cordierite has good adsorption effect on grease.
Description
Technical Field
The invention relates to a preparation method of porous cordierite, the cordierite prepared by the preparation method and new application of the cordierite, in particular to porous cordierite with high porosity and controllable pore size, a preparation method and application thereof.
Background
With the development of economy, science and technology and the like, the requirements of human beings on the types and the quantities of the grease are continuously developed. From industrial crude oil, gasoline, kerosene and diesel oil to edible oil and lubricating oil used in life, the method plays a critical role in production and life of people all the time. However, the grease inevitably generates discharge and leakage in the processes of production, transportation, storage and use, so that the grease flows into the water body. The national standard for discharging the grease into the water body is quite strict, and the maximum allowable discharge concentration of the oily wastewater is 10 mg/L. If a large amount of grease enters the water, an oil film is formed on the water surface, and the gas exchange between the water body and the atmosphere is prevented, so that the organisms in the water are irreparably influenced.
In order to treat waste oil in water bodies, there have been conventionally mainly physical methods and chemical methods. Common chemical methods are emulsion breaking and dispersing. The demulsification method is that chemical agents are decomposed in water to form positively charged emulsion groups, and the positively charged emulsion groups and negatively charged emulsified oil are subjected to electric neutralization, so that the purpose of water-oil separation is achieved. The dispersant method is to put surfactant in water to disperse grease into small particles, and the small particles are diluted in the whole water. The advantage of chemical methods is that large amounts of leaked grease can be quickly disposed of without further harm. However, the chemical method has obvious disadvantages that a large amount of chemical agents can cause secondary pollution to water bodies and even directly kill marine birds and marine mammals. The physical method mainly includes an adsorption method, an air floatation method, an electrochemical method, an ultrasonic separation method and the like. The adsorption method is characterized in that oil stains and other soluble organic matters in water are adsorbed on the surface by utilizing the porosity and large specific surface area of the adsorbent, so that water and oil separation is realized, the separation speed is high, the cost is low, and secondary pollution is basically avoided.
The most widely used adsorbent at present is natural diatomaceous earth. Diatomite is a natural siliceous rock with a porous structure, has the characteristics of porosity, small density, large specific surface area, good adsorbability and the like, and is suitable to be used as an adsorbent for grease. However, since diatomaceous earth is a natural mineral product, the quality of diatomaceous earth produced in various places is not the same. This results in two significant problems: firstly, the diatomite produced in each place has different sizes of apparent pores and different porosity, and directly influences the adsorption capacity of the diatomite on grease; secondly, because of natural mineral products, the diatomite produced in many places contains a large amount of heavy metals and radioactive substances, and if the diatomite is directly put into water, secondary pollution is caused to the water.
For the purification and modification of diatomite, a large amount of research is carried out by Chinese researchers. In patent CN105642237B, the diatomite is modified by undecenylamidopropyl betaine on the basis of purification, so that the adsorption capacity of the diatomite reaches 221.5 mg/g. In the patent CN105727903A, the diatomite is modified by dimethyl dipropenyl ammonium chloride on the basis of purification, so that the adsorption quantity reaches 242 mg/g. However, it is undeniable that in either method of purification and modification, a large amount of organic chemical reagents are used, which has an influence on the environment. In addition, in order to attach the modifier to the surface of the diatomite, the processes of heating, stirring, reflux reaction and the like are indispensable, so that the process is complicated, a large amount of energy is consumed, and the large-scale industrial production is not facilitated.
In order to replace diatomite, namely natural mineral with slightly smaller bulk density than water, after analyzing a large amount of mineral capable of being artificially synthesized, the cordierite is found to have small true density (2.6 g/cm)3) And the synthesis temperature is low, so that the method is convenient for mass production. If the apparent porosity is more than 50%, the bulk density of the porous cordierite is almost the same as that of seawater, and the porous cordierite can float and vibrate on the sea surface to adsorb grease. Furthermore, if the pore size of the porous cordierite can be controlled, the grease can be perfectly adsorbed, and the porous cordierite can replace the existing natural diatomite.
At present, the research on porous cordierite has mainly focused on the research on reducing the thermal expansion rate, and the grease adsorption effect of porous cordierite is rarely studied. Patent CN110903081A and patent CN110922205A use cordierite powder and PVA solution to mix, and after drying and sintering, porous cordierite is obtained. However, this patent does not mention the porosity and pore size of the porous cordierite produced. In patent CN111333412A, tetraethoxysilane is added into magnesium salt and aluminum salt to obtain sol, and then the obtained sol is dried to obtain gel, and porous cordierite is obtained after sintering. The pore diameter of the porous cordierite prepared by the method is fixed at 1-3 mu m and cannot be further adjusted, so that the synthesis method is not suitable for researching the function of the porous cordierite for absorbing grease. Patent CN108892476A discloses a porous cordierite block with apparent porosity of 28-38% is obtained by mixing and sintering aluminum source, magnesium source, silicon source material and rice bran for pore formation. The apparent pore size of such porous cordierite is unknown, and there is no room for further improvement in the apparent porosity.
In conclusion, there are few reports on the research on grease adsorption of porous cordierite instead of diatomite. Furthermore, the current mainstream method for synthesizing porous cordierite cannot effectively control the apparent porosity and the apparent pore size. Therefore, it is necessary to develop a method for adjusting the oil adsorption capability of porous cordierite by controlling the apparent porosity and the apparent pore size.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a preparation method of porous cordierite capable of adjusting and controlling the apparent porosity and the apparent pore size of cordierite; meanwhile, the invention also provides porous cordierite which has high porosity, large pore diameter and high specific surface area and can adsorb grease; finally, the invention also provides the application of the porous cordierite in grease adsorption.
In order to achieve the purpose, the invention adopts the technical scheme that: a method of producing porous cordierite, the method comprising the steps of:
(1) respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion of cordierite; the alumina source material comprises hydraulic alumina powder;
(2) mixing the raw materials weighed in the step (1), adding a pore-forming agent and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 0.1-1000 μm, and the addition amount of the pore-forming agent is 1-50% of the total weight of the raw materials in the step (1);
(3) and (3) forming and drying the mixture for forming obtained in the step (2), and crushing, finely grinding and screening after sintering to obtain the porous cordierite.
In the preparation method of the porous cordierite, cordierite (2 Al)2O3·2MgO·5SiO2) The chemical components are respectively weighed according to the proportion. The alumina source materialThe composite material comprises hydraulic alumina powder which is used as a source of alumina and a binding agent, and the binding agent is not required to be added when the porous cordierite is synthesized, so that the effect of killing two birds with one stone is achieved. The purities of the alumina source material, the magnesia source material and the silica source material are more than or equal to 99.5 percent, if the impurities in the raw materials are excessive, the performance of the prepared porous cordierite is influenced, and secondary damage to a water source is more likely to be caused by heavy metals or radiation substances in the impurities.
According to the preparation method of the porous cordierite, the pore-forming agent is added into the raw materials for synthesizing the cordierite, so that the pore-forming agent generates gas when being heated at high temperature, and the gas slowly overflows from the material and finally forms a pore structure. The use of the pore-forming agent can effectively reduce the bulk density of the formed body, reduce the thermal conductivity and save the use cost of raw materials.
In the preparation method of the porous cordierite, the pore-forming agent added in the step (2) has a diameter of 0.1-1000 μm. The pore former size directly affects the apparent pore size of the porous cordierite produced. The inventors of the present invention found in experimental studies that, if a pore former having a diameter of less than 0.1 μm is used, it is possible to produce porous cordierite having a pore size smaller than the minimum value (0.1 μm) of the pore size described in the present invention, and the adsorption capability of the resulting porous cordierite to fats and oils is remarkably lowered. However, if the pore former used is too large in diameter and exceeds the maximum value (1000 μm) of the pore former diameter described in the present invention, the porous cordierite produced will have too large a pore-forming diameter, and the powder will be insufficient in strength, and may be further broken into smaller sizes during use, and the adsorption performance of the porous cordierite to oils and fats will be significantly affected. Therefore, in order to balance the strength of the powder particles and the adsorption capability to the oil or fat, it is further preferable that the pore-forming agent has a diameter of 10 μm to 100 μm.
In the preparation method of the porous cordierite, the addition amount of the pore-forming agent added in the step (2) is 1-50% of the total weight of the raw materials in the step (1). Through experimental research, the inventor of the present application finds that the addition amount of the pore-forming agent is preferably 1 to 50% of the total weight of the alumina source material, the magnesia source material and the silica source material. If the addition amount of the pore former is less than 1% of the total weight of the alumina source material, the magnesia source material and the silica source material, the apparent porosity of the finally produced porous cordierite is less than 10%, and the adsorption amount of the porous cordierite to the grease does not reach an ideal state. If the pore-forming agent is added in an amount of more than 50% by weight based on the total weight of the alumina source material, the magnesia source material and the silica source material, the moldability of the mixture is deteriorated, and it is difficult to obtain a molded article having a sufficient strength. In addition, the use of a large amount of pore-forming agent generates excessive gas during sintering, and the apparent porosity of the finally prepared porous cordierite exceeds 70%, which directly results in insufficient strength of the porous cordierite powder and affects the performance of the porous cordierite.
In a preferred embodiment of the method for preparing porous cordierite according to the present invention, the pore-forming agent is added in the step (2) in an amount of 30 to 40% by weight based on the total weight of the raw materials in the step (1). The inventors of the present application have found that the adsorption capacity for grease can be improved by increasing the total apparent porosity of porous cordierite as much as possible while ensuring the strength of the porous cordierite. Further, when the total apparent porosity of the porous cordierite exceeds 50%, the bulk density of the porous cordierite approaches that of seawater, and the porous cordierite floats on the sea level, thereby increasing the adsorption probability of the oil. Therefore, the total apparent porosity of the obtained porous cordierite is preferably 50% to 70%; more preferably, the total apparent porosity of the obtained porous cordierite is 60% to 65%. The inventor of the present application has found that when the pore-forming agent added in the step (2) is added in an amount of 30 to 40% by weight based on the total weight of the raw materials in the step (1), the total apparent porosity of the porous cordierite obtained by the preparation can be controlled to be 50 to 70%, and more preferably 60 to 65%.
According to the preparation method of the porous cordierite, hydraulic alumina powder is adopted, so that the porous cordierite can be used as a source of alumina and a binding agent, and no additional binding agent is added; meanwhile, the apparent porosity and the apparent pore diameter of the finally obtained porous cordierite can be effectively controlled by controlling the diameter and the addition of the pore-forming agent, so that the finally prepared porous cordierite has the structural characteristics of low density, high porosity, large pore diameter and high specific surface area, and the obtained porous cordierite has the effect of adsorbing grease.
In a preferred embodiment of the method for producing porous cordierite according to the present invention, the weight of the hydraulic alumina powder in the step (1) is 10 to 100% of the weight of the alumina source material. In experimental studies, the inventors of the present invention have found that when the weight of the hydraulic alumina powder is 10% or less of the weight of the alumina source material, the binding force by the hydraulic alumina powder is insufficient, and the mixture is not molded. The price of the hydraulic alumina is 3 to 5 times of that of the common alumina powder, so based on the comprehensive consideration of the aspects of cost, binding capacity and the like, the weight of the hydraulic alumina powder in the step (1) is preferably 20 to 80 percent of that of the alumina source material; more preferably, the weight of the hydraulic alumina powder in the step (1) is 30-60% of the weight of the alumina source material.
In a preferred embodiment of the method for producing porous cordierite according to the present invention, in the step (3), porous cordierite having a central particle diameter D50 of 1 to 1000 μm is screened. The inventor of the application finds that the central particle size D50 of the porous cordierite is preferably 1-1000 μm. On the other hand, the smaller the central particle diameter D50 of the porous cordierite is, the larger the specific surface area of the porous cordierite is, and the more the adsorption capability to grease is enhanced under the same conditions. On the other hand, the smaller the particle diameter of the porous cordierite is, the smaller the average diameter of the pores becomes, and the adsorption capability of the porous cordierite to grease is affected. According to experimental studies of the inventors of the present application, it is known that if the central particle diameter of the porous cordierite is less than 100 μm, the average diameter of the open pores is less than 20 μm. As a more preferable embodiment of the method for producing porous cordierite according to the present invention, porous cordierite having a central particle diameter D50 of 100 to 300 μm is screened in the step (3). The inventor finds that the influence of the specific surface area and the average pore diameter of the porous cordierite on the grease adsorption capacity can be well balanced by screening the porous cordierite with the central particle size D50 of 100-300 mu m.
As a preferred embodiment of the method for preparing porous cordierite according to the present invention, the alumina source material in step (1) further includes at least one of common alumina powder, mullite powder, kaolinite powder, and magnesium aluminate spinel powder. The alumina source material of the present invention preferably comprises at least one of common alumina powder, mullite powder, kaolin powder and magnesium aluminate spinel powder in addition to hydraulic alumina powder.
As a preferable embodiment of the method for producing porous cordierite according to the present invention, in the step (1), the magnesia source material is at least one of magnesia powder, magnesium aluminate spinel powder, olivine powder, and enstatite powder. In the method for preparing porous cordierite, the magnesia source material is preferably, but not limited to, at least one of magnesia powder, magnesium aluminate spinel powder, olivine powder and enstatite powder.
As a preferred embodiment of the method for preparing porous cordierite according to the present invention, the silica source material in step (1) is at least one of silica powder, olivine powder, enstatite powder, mullite powder, and kaolinite powder. The silicon oxide source material is preferably but not limited to at least one of silicon oxide powder, olivine powder, enstatite powder, mullite powder and kaolinite powder.
As a preferred embodiment of the method for preparing porous cordierite according to the present invention, the pore-forming agent in step (2) is at least one of starch, carbon powder, ammonium bicarbonate, acryl resin powder, polystyrene powder, phenolic resin, and polyvinyl alcohol. The pore-forming agent is preferably, but not limited to, at least one of starch, carbon powder, ammonium bicarbonate, acrylic resin (PMMA) powder, Polystyrene (PS) powder, phenolic resin, and polyvinyl alcohol (PVA). Although porous cordierite is produced by using rice bran as a pore-forming agent in the patent literature of the prior art, rice bran itself is not an industrial product and cannot be controlled in terms of size, density and gas evolution, so that a satisfactory state cannot be achieved. Pore formers slowly decompose to gases during high temperature sintering, which gases cause microchannels of different diameters when permeating out of the shaped body. Two requirements must be met for the selection of the type of pore former: cannot be decomposed at too low a sintering temperature; the speed of decomposition cannot be too fast. If the material is decomposed at a relatively low temperature (100-200 ℃) or the decomposition speed is too high, the generation of the air holes, particularly small and medium-sized air holes, is not facilitated, and the material characteristics are influenced.
As a preferable embodiment of the method for producing porous cordierite according to the present invention, the drying in the step (3) is natural drying or low-temperature drying at a temperature of 50 to 110 ℃, and the water content of the molded body after drying is less than 3%; the sintering temperature is 1200-1400 ℃.
In the method for producing porous cordierite according to the present invention, the drying method of the molded mixture in the step (3) is natural drying or low-temperature drying. The temperature for low temperature drying generally does not exceed 110 ℃. Since the water content of the molded article is generally relatively large, if the drying temperature exceeds 110 ℃, cracking or even explosion inside the molded article may be caused. Finally, the water content of the dried molded article was less than 3%. If the water content is higher than 3%, gas molecules are formed by the internal water during sintering, which affects the formation of the pores of the porous cordierite.
In the preparation method of the porous cordierite, the sintering temperature in the step (3) is preferably 1200-1400 ℃. The inventor of the present application found in experiments that if the sintering temperature is below 1200 ℃, a cordierite crystal phase cannot be formed; if the sintering temperature exceeds 1400 ℃, the apparent porosity and the apparent pore size of the finally obtained porous cordierite are affected because the melting point of cordierite is exceeded. As a preferred embodiment of the method for producing porous cordierite according to the present invention, the sintering temperature in the step (3) is 1250 to 1350 ℃, which can better ensure the generation of cordierite crystal phase and the state of open pores.
In the method for preparing porous cordierite, porous cordierite sintered bodies obtained after sintering in the step (3) are crushed, crushed and finely ground by common crushing equipment to obtain porous cordierite powders with different sizes. Then, the obtained porous cordierite powder is screened by screens with different pore diameters, so that the porous cordierite powder with the total apparent porosity of 10-70% and the central particle diameter (D50) of 1-1000 μm is obtained.
In addition, the invention also provides the porous cordierite which has low density, high porosity, large pore diameter and high specific surface area and can adsorb grease, and the porous cordierite is prepared by the preparation method.
In a preferred embodiment of the porous cordierite according to the present invention, the porous cordierite has a total apparent porosity of 10 to 70%. The inventor of the present application has found, through research, that when the total apparent porosity of the porous cordierite is 10% to 70%, the bulk density of the porous cordierite is 0.8g/cm3～2.3g/cm3. In addition, on the premise of ensuring the strength of the porous cordierite, the adsorption capacity to grease can be improved only by increasing the total apparent porosity of the porous cordierite as much as possible. Further, when the total apparent porosity of the porous cordierite exceeds 50%, the bulk density of the porous cordierite approaches that of seawater, and the porous cordierite floats on the sea level, thereby increasing the adsorption probability of oil. As a more preferable embodiment of the porous cordierite according to the present invention, the porous cordierite has a total apparent porosity of 50% to 70%; in a more preferred embodiment of the porous cordierite according to the present invention, the porous cordierite has a total apparent porosity of 60 to 65%.
In a preferred embodiment of the porous cordierite of the present invention, the porous cordierite has a mean diameter of 0.1 to 100 μm in apparent pore size. The average diameter range of the pores of the porous cordierite prepared by the preparation method is 0.1-100 mu m. According to the studies of the present inventors, when the type of pore former, the amount of the pore former to be charged, and the center particle diameter of the finally produced powder are the same, the pore former size increases, and the pore size of the finally produced porous cordierite increases. On the other hand, when the particle diameters are the same, the larger the pore size of the porous cordierite powder is, the higher the amount of oil adsorbed is. Therefore, in view of the grease-adsorbing ability, the porous cordierite preferably has a mean diameter of pores ranging from 10 to 100 μm.
As the inventionA preferred embodiment of the porous cordierite has a bulk density of 0.8 to 2.3g/cm3。
In a preferred embodiment of the porous cordierite of the present invention, the porous cordierite has a central particle diameter D50 of 1 to 1000 μm. The inventor of the present application has found that the porous cordierite preferably has a central particle diameter D50 of 1 to 1000. mu.m. On the other hand, the smaller the central particle diameter D50 of the porous cordierite is, the larger the specific surface area of the porous cordierite is, and the more the adsorption capability to grease is enhanced under the same conditions. On the other hand, the smaller the particle diameter of the porous cordierite is, the smaller the average diameter of the pores becomes, and the adsorption capability of the porous cordierite to grease is affected. According to experimental studies of the inventors of the present application, it is known that if the central particle diameter of the porous cordierite is less than 100 μm, the average diameter of the open pores is less than 20 μm. Therefore, in a more preferred embodiment of the porous cordierite according to the present invention, the central particle diameter D50 of the porous cordierite is 100 to 300 μm, and the influence of the specific surface area and the average pore diameter of the porous cordierite on the grease-adsorbing ability can be more favorably balanced.
Finally, the invention also provides the application of the porous cordierite for adsorbing grease. The porous cordierite is prepared from specific raw materials and a preparation method, and has specific apparent porosity, apparent pore size, bulk density, central particle size and the like, so that the porous cordierite has the function of absorbing grease, and provides a new material selection for the field of oil stain treatment.
As a preferable embodiment of the application of the porous cordierite in grease adsorption, the adsorption amount of the porous cordierite on grease is 20-200 mg/g. The inventor of the application finds that the porous cordierite with specific apparent porosity, apparent pore size, bulk density, center particle size and the like has the adsorption capacity of 20-200 mg/g for grease when used for treating oil stains, particularly has the maximum treatment capacity of 200mg/g, and is very close to the treatment capacity of the existing diatomite.
As a preferable embodiment of the application of the porous cordierite of the present invention to adsorption of grease, the grease is at least one of crude oil, diesel oil, lubricating oil, vegetable oil, and gasoline. The porous cordierite of the present invention adsorbs grease, including but not limited to crude oil, diesel oil, lubricating oil, vegetable oil, gasoline, and the like.
According to the preparation method of the porous cordierite, the alumina source material comprises hydraulic alumina powder which can be used as both the source of alumina and a binding agent, and the porous cordierite powder is successfully prepared by utilizing the binding force action of the hydraulic alumina powder without adding any binding agent under the wet preparation condition. Meanwhile, in the preparation method of the porous cordierite, the apparent porosity, the apparent pore size and the bulk density of the obtained porous cordierite powder are effectively controlled by controlling the size and the using amount of the pore-forming agent, the central particle size of the finally prepared porous cordierite powder and the like, so that the prepared porous cordierite has a good adsorption effect on grease. Meanwhile, the preparation method has simple process steps and low cost, and is beneficial to large-scale popularization and application.
The porous cordierite is prepared by the specific method, has apparent porosity, apparent pore size, bulk density and center particle size in specific ranges, has good adsorption effect on grease, and can be used in the field of oil stain treatment. The porous cordierite disclosed by the invention is applied to grease adsorption, the maximum grease adsorption capacity of the porous cordierite can reach 200mg/g, the processing capacity of the porous cordierite is very close to that of the conventional diatomite, and a new material selection is provided for the field of oil stain treatment.
Detailed Description
To better illustrate the objects, technical solutions and advantages of the present invention, the present invention will be further described with reference to specific embodiments.
The starting materials used in the following examples of the present invention are either directly commercially available or prepared according to conventional methods in the art, unless otherwise specified. For example, the hydraulic alumina powder may be purchased directly from hydraulic alumina BK-112 of Sumitomo corporation or from a product of another manufacturer, or prepared according to a conventional method in the art.
The purities of the alumina source material, the magnesia source material and the silica source material adopted in the following examples are more than or equal to 99.5%.
Example 1
In one embodiment of the porous cordierite according to the present invention, the porous cordierite according to the present embodiment is prepared by the following method:
(1) according to cordierite (2 Al)2O3·2MgO·5SiO2) Respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion; the alumina source material comprises the following components in percentage by mass: 10% of hydraulic alumina powder and 90% of common alumina powder; the magnesium oxide source material is magnesium oxide powder; the silicon oxide source material is silicon oxide powder;
(2) mixing the raw materials weighed in the step (1), adding pore-forming agent acrylic resin (PMMA) powder and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 10 mu m, and the addition amount of the pore-forming agent is 20% of the total weight of the raw materials in the step (1);
(3) forming and drying the mixture for forming obtained in the step (2), drying the mixture by natural drying or low-temperature drying at 50-110 ℃ until the water content of a formed body is lower than 3%, then sintering at 1250 ℃, crushing and finely grinding after sintering, and screening out porous cordierite with the central particle size D50 of 30 mu m to obtain the porous cordierite of the embodiment; the central particle diameter D50 was measured by a laser profiler MS2000 (malvern instruments, uk).
Example 2
In one embodiment of the porous cordierite according to the present invention, the porous cordierite according to the present embodiment is prepared by the following method:
(1) according to cordierite (2 Al)2O3·2MgO·5SiO2) Respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion; the alumina source material is hydraulic alumina powder; the above-mentionedThe magnesia source material is magnesium aluminate spinel powder; the silicon oxide source material is olivine powder;
(2) mixing the raw materials weighed in the step (1), adding pore-forming agent phenolic resin and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 50 mu m, and the addition amount of the pore-forming agent is 25 percent of the total weight of the raw materials in the step (1);
(3) forming and drying the mixture for forming obtained in the step (2), drying the mixture by natural drying or low-temperature drying at 50-110 ℃ until the water content of a formed body is lower than 3%, then sintering the formed body at 1350 ℃, crushing and finely grinding the sintered body, and screening out porous cordierite with the central particle size D50 of 70 mu m to obtain the porous cordierite of the embodiment; the central particle diameter D50 was measured by a laser profiler MS2000 (malvern instruments, uk).
Example 3
In one embodiment of the porous cordierite according to the present invention, the porous cordierite according to the present embodiment is prepared by the following method:
(1) according to cordierite (2 Al)2O3·2MgO·5SiO2) Respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion; the alumina source material comprises the following components in percentage by mass: 25% of hydraulic alumina powder and 75% of mullite powder; the magnesium oxide source material is olivine powder; the silicon oxide source material is enstatite powder;
(2) mixing the raw materials weighed in the step (1), adding a pore-forming agent Polystyrene (PS) powder and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 100 mu m, and the addition amount of the pore-forming agent is 1 percent of the total weight of the raw materials in the step (1);
(3) forming and drying the mixture for forming obtained in the step (2), drying the mixture by natural drying or low-temperature drying at 50-110 ℃ until the water content of a formed body is lower than 3%, then sintering the formed body at 1300 ℃, crushing and finely grinding the sintered body, and screening out porous cordierite with the central particle size D50 of 550 mu m to obtain the porous cordierite of the embodiment; the central particle diameter D50 was measured by a laser profiler MS2000 (malvern instruments, uk).
Example 4
In one embodiment of the porous cordierite according to the present invention, the porous cordierite according to the present embodiment is prepared by the following method:
(1) according to cordierite (2 Al)2O3·2MgO·5SiO2) Respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion; the alumina source material comprises the following components in percentage by mass: 40% of hydraulic alumina powder and 60% of kaolin powder; the magnesium oxide source material is enstatite powder; the silicon oxide source material is mullite powder;
(2) mixing the raw materials weighed in the step (1), adding pore-forming agents polyvinyl alcohol (PVA) and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 250 mu m, and the addition amount of the pore-forming agent is 50 percent of the total weight of the raw materials in the step (1);
(3) forming and drying the mixture for forming obtained in the step (2), drying the mixture by natural drying or low-temperature drying at 50-110 ℃ until the water content of a formed body is lower than 3%, then sintering the formed body at 1350 ℃, crushing and finely grinding the sintered body, and screening out porous cordierite with the central particle size D50 of 650 microns to obtain the porous cordierite of the embodiment; the central particle diameter D50 was measured by a laser profiler MS2000 (malvern instruments, uk).
Example 5
In one embodiment of the porous cordierite according to the present invention, the porous cordierite according to the present embodiment is prepared by the following method:
(4) according to cordierite (2 Al)2O3·2MgO·5SiO2) Respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion; the alumina source material comprises the following components in percentage by mass: 90% of hydraulic alumina powder and 10% of magnesium aluminate spinel powder; the magnesium oxide source material is magnesium oxide powder and enstatite powder with the mass ratio of 1: 1; the silicon oxide source material is kaolinite powder；
(5) Mixing the raw materials weighed in the step (1), adding pore-forming agents polyvinyl alcohol (PVA) and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 0.1 mu m, and the addition amount of the pore-forming agent is 2% of the total weight of the raw materials in the step (1);
(6) forming and drying the mixture for forming obtained in the step (2), drying the mixture by natural drying or low-temperature drying at 50-110 ℃ until the water content of a formed body is lower than 3%, then sintering at 1200 ℃, crushing and fine grinding after sintering, and screening out porous cordierite with the central particle size D50 of 1 mu m to obtain the porous cordierite of the embodiment; the central particle diameter D50 was measured by a laser profiler MS2000 (malvern instruments, uk).
Example 6
In one embodiment of the porous cordierite according to the present invention, the porous cordierite according to the present embodiment is prepared by the following method:
(1) according to cordierite (2 Al)2O3·2MgO·5SiO2) Respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion; the alumina source material comprises the following components in percentage by mass: 80% of hydraulic alumina powder and 20% of mullite powder; the magnesium oxide source material is olivine powder; the silicon oxide source material is prepared from the following components in a mass ratio of 2: 1, a mixture of silica powder and kaolinite powder;
(2) mixing the raw materials weighed in the step (1), adding pore-forming agent phenolic resin and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 1000 mu m, and the addition amount of the pore-forming agent is 49 percent of the total weight of the raw materials in the step (1);
(3) forming and drying the mixture for forming obtained in the step (2), drying the mixture by natural drying or low-temperature drying at 50-110 ℃ until the water content of a formed body is lower than 3%, then sintering the formed body at 1400 ℃, crushing and finely grinding the sintered body, and screening out porous cordierite with the central particle size D50 of 1000 microns to obtain the porous cordierite of the embodiment; the central particle diameter D50 was measured by a laser profiler MS2000 (malvern instruments, uk).
Example 7
Performance testing of the porous cordierite of the present invention
In this embodiment, a test group and a control group are provided, the test group 1 to 6 respectively adopt the porous cordierite prepared in the embodiments 1 to 6, and the control group 1 to 10 respectively include the following porous cordierite:
the selection of the alumina source material for the porous cordierite of control 1 is different from that of example 1, and the selection of the other raw materials and the preparation method are the same as those of example 1. In the preparation method of the porous cordierite of the comparison group 1, the alumina source material comprises the following components in percentage by mass: 9% of hydraulic alumina powder and 91% of common alumina powder. In the preparation of the porous cordierite of the control group, since the hydraulic alumina powder is added in a small amount, in the step (3), since the hydraulic alumina powder cannot provide sufficient binding force, the molded body is decomposed due to insufficient strength of the molded body at the time of molding and demolding of the molded mixture, and subsequent sintering and performance test cannot be performed.
The porous cordierite of control 2 was prepared in the same manner as in example 2 except that the pore-forming agent was selected in the same manner as in example 2. In the preparation of the porous cordierite of control group 2, the pore-forming agent was ammonium bicarbonate.
The porous cordierite of control 3 was prepared in the same manner as in example 3 except that the amount of the pore-forming agent added was different from that in example 3. Control 3 in the preparation of porous cordierite, the amount of pore-forming agent added was 0.5% of the total weight of the raw materials in step (1).
The porous cordierite of control 4 was prepared in the same manner as in example 5 except that the pore-forming agent was added in an amount different from that in example 5. Control 4 the porous cordierite was prepared by adding pore former in an amount of 51% by weight based on the total weight of the raw materials in step (1).
The porous cordierite of control 5 was prepared in the same manner as in example 4 except that the pore former had a different diameter from that of example 4. Control 5 the pore former was 0.01 μm in diameter in the preparation of porous cordierite.
Comparative example 6 the porous cordierite was prepared in the same manner as in example 6 except that the pore-forming agent was different in diameter from that in example 6. Control 6 the pore former was 1100 μm in diameter in the preparation of porous cordierite.
The porous cordierite of control 7 was prepared by the same method as that of example 2 except that the sintering temperature in step (3) was different from that in example 2. Control 7 the sintering temperature in step (3) was 1150 c in the production of porous cordierite.
The porous cordierite of control 8 was prepared in the same manner as in example 4 except that the sintering temperature in step (3) was different from that in example 4. Control 8 the sintering temperature in step (3) was 1450 c for the production of porous cordierite.
The porous cordierite of control 9 was prepared in the same manner as in example 1 except that the porous cordierite having the central particle diameter D50 screened in step (3) was different from that of example 1. In the production of the porous cordierite according to control 9, the porous cordierite having a central particle diameter D50 of 0.5 μm was screened in step (3).
The porous cordierite of control 10 was prepared in the same manner as in example 3 except that the porous cordierite having the central particle diameter D50 screened in step (3) was different from that of example 3. In the production of the porous cordierite according to control 10, porous cordierite having a central particle diameter D50 of 1100 μm was screened in step (3).
And respectively testing the total apparent porosity, the average diameter of the apparent pores, the bulk density and the grease adsorption capacity of the porous cordierite of the test groups 1-6 and the porous cordierite of the control groups 1-10. The test methods are respectively as follows:
total apparent porosity and average apparent pore diameter: according to GB/T1966-2006 volume-weight test method for porous ceramic gas-developing rate, the total gas-developing rate and the average diameter of gas-developing pores of each group of porous cordierite were measured by a DXR porous ceramic gas-developing rate volume tester (Hunan Tan Gaokou instruments manufacturing Co., Ltd.).
Bulk density: the bulk density of each group of porous cordierite was measured by a porous ceramic density measuring instrument AU-1200VP (Kostesquarrz, Germany) in accordance with QB/T1010-2015 method for measuring bulk density of ceramic materials and pigments.
Oil adsorption capacity: the infrared spectrum method specifically comprises the following steps: 1.0g of porous cordierite is placed in a 250mL conical flask, 100mL of engine oil solution with the concentration of 500mg/L is added, and the pH value of the solution is adjusted to be within the range of 5.0-9.0. Oscillating for 1 hour at room temperature, taking supernatant, measuring the concentration of oil in the solution by using an infrared spectrometer, and calculating the oil adsorption capacity of the porous cordierite according to the concentration difference of the oil in the water before and after adsorption. According to the experimental result of the inventor, the maximum adsorption amount of the grease can be obtained by shaking for 0.5 hour at room temperature.
The results of the tests for each group are shown in table 1.
TABLE 1 test results of the Performance test of the porous cordierite of the test group and the control group
As is clear from the results in Table 1, the porous cordierite of test group 6 had a total apparent porosity of 69% and a bulk density of 0.8g/cm3The average diameter of the air holes is 100 μm, and the final oil absorption amount reaches 200mg/g, which is close to the oil absorption capacity of the existing diatomite.
In the above control group 1, since the amount of the hydraulic alumina powder added in the alumina source material during the preparation of the porous cordierite is relatively small (9%), after the alumina source material, the magnesia source material, the silica source material, the pore-forming agent and the like are mixed, the hydraulic alumina powder cannot provide sufficient binding force, so that when the molding mixture is molded and demolded, the molded body is disintegrated due to insufficient strength, and subsequent sintering and performance evaluation cannot be continued.
In control 2, the pore former used was ammonium bicarbonate. Since ammonium bicarbonate has a low decomposition temperature and is completely decomposed at a relatively low sintering temperature, and thus cannot form fine gas channels during cordierite formation, the porous cordierite powder after sintering has a total apparent porosity of 2% and a bulk density of 2.6g/cm3Finally, the grease adsorption capacity is 3mg/g, and the obtained porous cordierite has weak grease adsorption capacity and cannot be effectively used for oil stain treatment.
In the control group 3, in the preparation process of the porous cordierite, the addition amount of the pore-forming agent is 0.5% of the total weight of the raw materials in the step (1), and the addition amount of the pore-forming agent is too small, so that the total apparent porosity of the prepared porous cordierite is 9%, the oil adsorption amount of the porous cordierite is small, and the obtained porous cordierite has weak oil adsorption capacity and cannot be effectively used for oil stain treatment.
In the control group 4, in the preparation process of the porous cordierite, the addition amount of the pore-forming agent is 51% of the total weight of the raw materials in the step (1), and too much addition amount of the pore-forming agent directly results in insufficient strength of the prepared porous cordierite powder, and during the test, the prepared porous cordierite large-particle powder with the average particle size of 900 μm is further broken into small-particle powder, so that the test significance is lost.
In the control group 5, in the preparation process of the porous cordierite, the pore former used is small in size (the diameter is 0.01 μm), so that the average pore diameter of the prepared porous cordierite is 0.05 μm, and the grease adsorption capacity of the obtained porous cordierite is only 2mg/g, and the grease adsorption capacity is weak, so that the porous cordierite cannot be effectively used for oil stain treatment.
In the above control group 6, during the preparation of the porous cordierite, the size of the pore former used is large (the diameter is 1100 μm), which results in insufficient strength of the prepared porous cordierite powder, and subsequent performance tests cannot be performed.
In the above control 7, the sintering temperature of the porous cordierite is 1150 ℃ and the lowest cordierite formation temperature is not reached during the preparation process, and the result of XRD analysis shows that the proportion of the cordierite phase is less than 10%, so that no further performance test is performed.
In the control group 8, the porous cordierite was melted during sintering because the sintering temperature was 1450 ℃ and exceeded the intrinsic melting point of cordierite during the production process, and subsequent pulverization and further testing could not be performed.
In the control group 9, the central particle size of the porous cordierite powder prepared in the preparation process of the porous cordierite is 0.5 μm due to the fact that the porous cordierite powder is too fine in the processes of crushing, fine grinding and screening, and the central particle size of the obtained porous cordierite is too small, which directly results in that the average diameter of pores of the prepared porous cordierite is smaller (0.5 μm), so that the porous cordierite has smaller grease adsorption capacity and weaker grease adsorption capacity, and cannot be effectively used for grease treatment.
In the control group 10, in the preparation process of the porous cordierite, the central particle size of the prepared porous cordierite powder is 1100 μm due to the fact that the porous cordierite is too coarse in the processes of crushing, fine grinding and screening, the central particle size of the obtained porous cordierite is too large, the specific surface area of the porous cordierite is too small, the adsorption capacity on grease is influenced, and finally, the grease adsorption capacity of the obtained porous cordierite is 19mg/g through testing, the porous cordierite has weak grease adsorption capacity, and cannot be effectively used for oil stain treatment.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.
Claims (10)
1. A method for producing porous cordierite, comprising the steps of:
(1) respectively weighing an alumina source material, a magnesia source material and a silica source material according to the chemical component proportion of cordierite; the alumina source material comprises hydraulic alumina powder;
(2) mixing the raw materials weighed in the step (1), adding a pore-forming agent and water, and fully mixing to obtain a mixture for forming; the diameter of the pore-forming agent is 0.1-1000 μm, and the addition amount of the pore-forming agent is 1-50% of the total weight of the raw materials in the step (1);
(3) and (3) forming and drying the mixture for forming obtained in the step (2), and crushing, finely grinding and screening after sintering to obtain the porous cordierite.
2. The method for preparing porous cordierite according to claim 1, wherein the weight of the hydraulic alumina powder in the step (1) is 10 to 100% of the weight of the alumina source material; preferably, the weight of the hydraulic alumina powder in the step (1) is 20-80% of the weight of the alumina source material.
3. The method for producing porous cordierite according to claim 1, wherein porous cordierite having a central particle diameter D50 of 1 to 1000 μm is screened in the step (3).
4. The method for preparing porous cordierite according to claim 1 or 2, wherein the alumina source material in the step (1) further comprises at least one of ordinary alumina powder, mullite powder, kaolinite powder and magnesium aluminate spinel powder; the magnesium oxide source material is at least one of magnesium oxide powder, magnesium aluminate spinel powder, olivine powder and enstatite powder; the silicon oxide source material is at least one of silicon oxide powder, olivine powder, enstatite powder, mullite powder and kaolinite powder.
5. The method for preparing porous cordierite according to claim 1, wherein the pore-forming agent in step (2) is at least one of starch, carbon powder, ammonium bicarbonate, acryl resin powder, polystyrene powder, phenolic resin, and polyvinyl alcohol.
6. The method for preparing porous cordierite according to claim 1, wherein the drying in the step (3) is natural drying or low-temperature drying, the temperature of the low-temperature drying is 50-110 ℃, and the water content of the molded body after the drying is lower than 3%; the sintering temperature is 1200-1400 ℃.
7. A porous cordierite produced by the production method according to any one of claims 1 to 6.
8. The porous cordierite of claim 7, having a total apparent porosity of 10 to 70%, a mean diameter of the apparent pores of 0.1 to 100 μm, and a bulk density of 0.8 to 2.3g/cm3(ii) a The central particle diameter D50 of the porous cordierite is 1-1000 μm.
9. Use of the porous cordierite according to claim 7 or 8 for adsorbing grease.
10. The application of the porous cordierite for adsorbing the grease according to claim 9, wherein the adsorption amount of the porous cordierite to the grease is 20-200 mg/g; preferably, the grease is at least one of crude oil, diesel oil, lubricating oil, vegetable oil and gasoline.
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