In the tropics, lowland rice cultivation is often confronted with the problem of iron toxicity. The solution proposed by research in general is the use of industrial silicon. However, the high cost of industrial silic...In the tropics, lowland rice cultivation is often confronted with the problem of iron toxicity. The solution proposed by research in general is the use of industrial silicon. However, the high cost of industrial silicon limits its adoption by farmers. A study was carried out in Zakogbeu;Center-West of Côte d’Ivoire, to assess the potential of kaolin to mitigate the effect of this soil constraint on the root of the rice plant. Five kaolin-based treatments were analyzed (T<sub>0 </sub>= 0 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>1</sub> = 366 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>2</sub> = 736 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>3</sub> = 1097 kg kaolin ha<sup>−</sup><sup>1</sup> and T<sub>4</sub> = 1465 kg kaolin ha<sup>−</sup><sup>1</sup> are 0, 200, 400, 600 and 800 kg SiO<sub>2</sub> ha<sup>−</sup><sup>1</sup>) in a device in complete random blocks, with 5 repetitions. The results obtained show that kaolin supply increases the length of the root tissue as well as the number of branching of the root of the rice plant. Root tissue increased from 10 cm with T<sub>0</sub> treatment to more than 15 cm with treatment T<sub>4</sub>. The microscopic observation of the roots shows that in the treatment T<sub>0</sub>, the roots present only primary ramifications and the tertiary and quaternary ramifications are observed with the treatments T<sub>3</sub> and T<sub>4</sub>. The contribution of kaolin is an alternative to inhibit the effect of iron toxicity on the rice plant root development in iron toxicity condition.展开更多
In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy ef...In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy efficiency of various industrial applications by minimizing heat loss and temperature control. These panels function as silent protectors, aiding in reducing energy consumption and making things more sustainable and better for the environment. This is where composite materials come in;they are known for their lightweight nature, high strength-to-weight ratio, and excellent thermal insulation properties and have gained significant attention. Researchers are actively engaged in various studies aimed at enhancing these materials further. This research project focuses on the development of kaolin and glass fiber-reinforced composites for thermally insulating panels, to which natural strengthening materials like corn husk and bamboo fibers are added. The aim is to create cost-effective and efficient composite materials for thermal insulation applications by incorporating these components with a binder consisting of potassium silicate, hydroxide, and distilled water. This project involves conducting compression tests, bending tests, impact tests, thermal conductivity measurements, and microscopic analysis to evaluate the mechanical and thermal properties of the developed composites. The profound impact of these engineered composites on thermal insulation panels stands to revolutionize energy conservation efforts, offering a potent avenue to minimize heat loss and enhance overall energy efficiency across an array of industrial sectors.展开更多
This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinat...This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinations at 850<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C, to transform the kaolin to a more reactive metakaolin. Afterwards, the extremely reactive metakaolin was purge with sulphuric acid to obtain the much needed silica-alumina ratio for zeolite X synthesis. An alkaline fusion stage was then carried out to transform the metakaolin into zeolite by mixing with aqueous NaOH to form gel then allowed to stay for a duration of seven days at room temperature. The samples were then charged into a propylene container and placed in an oven at a temperature of 100<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C for the reaction to take place for 6 h. Identification of the crystalline phases by X-ray Diffraction (XRD), chemical/elemental compositions by X-ray Fluorescence (XRF)/Energy Dispersive Spectroscopic analyses (EDS), surface morphology by Scanning Electron Microscopy (SEM) and molecular vibration of units by Fourier Transform Infrared Spectrophotometry (FT-IR) were done. The results showed that the zeolite synthesized from Chokocho kaolin (CK) was more crystalline/larger with sharper peaks on both XRD and FTIR than that from Kono-Boue. This was also supported by slightly rougher surface morphology of CK over KK on SEM. XRF Si:Al ratios of 10.73 and 14.36 were obtained for KK and CK respectively. EDS results supported the XRF ratios. Sharper zeolitic characteristic O-H stretching bands at 3488 and 3755 cm<sup>-1</sup> were recorded for CK than KK. However, both results showed that zeolite X have been produced from both Kono-Boue and Chokocho kaolin clays respectively.展开更多
The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron micr...The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron microscopy, tensile tests, and thermal resistance). The results obtained showed that kaolin, an inert material, prevents the starch from losing its granular structure and to solubilize during the heating, generating plastic films of low Young’s modulus (7 MPa). On the other hand, metakaolin, an amorphous and dehydroxylated material obtained after heating of kaolin at 700°C for 1 hour, substantially improves the thermomechanical properties of the plastic films. The Young’s modulus increases from 19 MPa to 25 MPa while the thermal resistance increases from 90°C to 120°C. This was attributed to good dispersion of the metakaolin in the polymer matrix after the loss of the granular structure of the starch during heating.展开更多
This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montm...This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system.展开更多
Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃~550℃ in order to obtain suitable liquid fuels.The dependenci...Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃~550℃ in order to obtain suitable liquid fuels.The dependencies between process temperatures,types of catalyst,feed compositions and product yields of the obtained fuel fractions were found.It was observed that up to 450℃ thermal cracking temperature,the major product of pyrolysis was liquid oil and the major product at other higher temperatures(475℃~550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃.Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction.Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil.Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature.The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively.On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.展开更多
Well-crystallized high-silica NaY zeolites (Si/Al〉2.5) were prepared from a reaction mixture consisting of metakaolin, sodium silicate solution and seed solution via optimization of the mixture composition and reac...Well-crystallized high-silica NaY zeolites (Si/Al〉2.5) were prepared from a reaction mixture consisting of metakaolin, sodium silicate solution and seed solution via optimization of the mixture composition and reaction conditions. The transformation from kaolin to high-silica NaY zeolite was confirmed by XRD, SEM and IR techniques. Subsequently, the influence of synthesis parameters, i.e. initial SIO2/Al2O3, initial Na2O/SiO2, initial H2O/SiO2, aging time of the seed solution, crystallization temperature and crystallization time, on the NaY growth was investigated in terms of crystallinity and Si/Al ratio. The results showed that the effects of initial SiO2/Al2O3, initial Na2O/SiO2 and initial H2O/ SiO2 on the crystaIlinity and Si/Al ratio of NaY zeolite are similar to those observed in the conventional syntheses of NaY zeolites only using sodium silicate solution as silicon source. However, due to the use of metakaolin as the main silicon and aluminum sources in the present study, a long crystallization induction period of 20 h was achieved, which can be attributed to the dissolution of metakaolin. In addition, different from the conventional syntheses of zeolite NaY, pure NaY zeolites (i.e. without NaP zeolite impurity) were still obtained even at 120℃ because of the use of a large quantity of seed solution (23 wt%) in the reaction mixture. As the aging time of the seed solution increased from 3.5 h to 22 h, the relative crystallinity of the NaY zeolite first increased sharply and then reached a plateau, while the Si/Al ratio first increased rapidly up to a maximum value of 2.75 corresponding to an aging time of 6.5 h, and then decreased sharply with the aging time.展开更多
NaY zeolites were in-situ synthesized from coal-based kaolin via thehydrothermal method. The effects of various factors on the structure of the samples were extensivelyinvestigated. The samples were characterized by N...NaY zeolites were in-situ synthesized from coal-based kaolin via thehydrothermal method. The effects of various factors on the structure of the samples were extensivelyinvestigated. The samples were characterized by N_2 adsorption, XRD, IR and DTG-DTA methods, andthe results show that the crystallization temperature and amount of added water play an importantrole in the formation of the zeolite structure. The 4A and P zeolites are the competitive phasepresent in the resulting product. However, NaY zeolites with a higher relative crystallinity,excluding impure crystals and the well hydrothermal stability, can be synthesized from coal-basedkaolin. These zeolites possess a larger surface area and a narrow pore size distribution, and thismeans that optimization of this process might result in a commercial route to synthesize NaYzeolites from coal-based kaolin.展开更多
Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments.Oil contents(mass fraction) of 4%,8%,12%,16% and 20% were selected to represent different contamina...Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments.Oil contents(mass fraction) of 4%,8%,12%,16% and 20% were selected to represent different contamination degrees,and the soil specimens were manually prepared through mixing and static compaction method.Initial water content and dry density of the test kaolin clay were controlled at 10% and 1.58 g/cm^3,respectively.Test results indicate that since part of the diesel oil will be released from soil by evaporation,the real water content should be derived through calibration of the quasi water content obtained by traditional test method.As contamination degree of the kaolin clay increases,both liquid limit and plastic limit decrease,but there's only a slight increase for plasticity index.Swelling pressure of contaminated kaolin clay under confined condition will be lowered when oil-content gets higher.Unconfined compressive strength(UCS) of the oil-contaminated kaolin clay is influenced by not only oil content but also curing period.Increase of contamination degree will continually lower UCS of the kaolin clay specimen.In addition,electrical resistivity of the contaminated kaolin clay with given water content decreases with the increase of oil content.However,soil resistivity is in good relationship with oil content and UCS.Finally,oil content of 8% is found to be a critical value for engineering property of kaolin clay to transit from water-dominated towards oil-dominated characteristics.展开更多
Calcination and acid leaching of coal kaolin were studied to determine an effective and economical preparation method of calcined kaolin. Thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffracti...Calcination and acid leaching of coal kaolin were studied to determine an effective and economical preparation method of calcined kaolin. Thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD) demonstrated that 900&#176;C was the suitable temperature for the calcination. Leaching tests showed that hydrochloric acid was more effective for iron dissolution from raw coal kaolin (RCK), whereas oxalic acid was more effective on iron dissolution from calcined coal kaolin (CCK). The iron dissolution from CCK was 28.78wt%, which is far less effective than the 54.86wt% of RCK under their respective optimal conditions. Through analysis by using M?ssbauer spectroscopy, it is detected that nearly all of the structural ferrous ions in RCK were removed by hydrochloric acid. However, iron sites in CCK changed slightly by oxalic acid leaching because nearly all ferrous ions were transformed into ferric species after firing at 900&#176;C. It can be concluded that it is difficult to remove the structural ferric ions and ferric oxides evolved from the structural ferrous ions. Thus, iron removal by acids should be conducted prior to calcination.展开更多
Kaolin geopolymers were produced by the alkali-activation of kaolin with an activator solution (a mixture of NaOH and sodium silicate solutions). The NaOH solution was prepared at a concentration of 6-14 mol/L and w...Kaolin geopolymers were produced by the alkali-activation of kaolin with an activator solution (a mixture of NaOH and sodium silicate solutions). The NaOH solution was prepared at a concentration of 6-14 mol/L and was mixed with the sodium silicate solution at a Na2SiO3/NaOH mass ratio of 0.24 to prepare an activator solution. The kaolin-to-activator solution mass ratio used was 0.80. This paper aimed to analyze the effect of NaOH concentration on the compressive strength of kaolin geopolymers at 80℃ for 1, 2, and 3 d. Kaolin geopolymers were stable in water, and strength results showed that the kaolin binder had adequate compressive strength with 12 mol/L of NaOH concentration. When the NaOH concentration increased, the SiO2/Na20 decreased. The increased Na20 content enhanced the dissolution of kaolin as shown in X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. However, excess in this content was not beneficial for the strength development of kaolin geopolymers. In addition, there was the formation of more geopolymeric gel in 12 mol/L samples. The XRD pattern of the samples showed a higher amorphous content and a more geopolymer bonding existed as proved by FTIR analysis.展开更多
Calcined kaolin/TiO2 composite particle material (CK/TCPM) was prepared with TiO2 coating on the surfaces of calcined kaolin particles by the mechano-chemical method. X-ray diffraction (XRD) and scanning electron ...Calcined kaolin/TiO2 composite particle material (CK/TCPM) was prepared with TiO2 coating on the surfaces of calcined kaolin particles by the mechano-chemical method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to investigate the microstructures and morphologies, respectively. The mechanism of the mechano-chemical reaction between calcined kaolin and TiO2 was studied by infrared spectra (IR). The results show that TiO2 coats evenly on the surfaces of calcined kaolin particles by Si-O-Ti and Al-O-Ti bonds on their interfaces. The hiding power and whiteness of CK/TCPM are 17.12 g/m^2 and 95.7%, respectively, presenting its similarity to TiO2 in pigment properties.展开更多
Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low h...Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.展开更多
Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treat...Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different.XRD pattern of the kaolin calcined at 600°C or 900°C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100°C showed obvious peaks forγ-Al2 O3.Therefore,the nickel-based catalysts exhibited different physic-chemical properties.Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100 N CA-900 N CA-1400 N CA-600 N KA≈0 at temperatures of 350–650°C and a space velocity of 120 L·g-1·h-1.Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation.展开更多
This paper has provided an effective method to utilize the filter residue. A Y zeolite-containing composite and a fluid catalytic cracking(FCC) catalyst had been successfully prepared by an in-situ crystallization tec...This paper has provided an effective method to utilize the filter residue. A Y zeolite-containing composite and a fluid catalytic cracking(FCC) catalyst had been successfully prepared by an in-situ crystallization technology using filter residue and kaolin as raw materials. The samples were characterized by XRD, FT-IR, SEM, and N_2 adsorption-desorption techniques and evaluated in a bench FCC unit. In comparison to the reference samples synthesized from single kaolin,the silica/alumina molar ratio, the external surface area, and the total pore volume of the composite increased by 16.2%,14.5%, and 16.2%, respectively. The catalyst possessed more meso-and macro-pores and more acid sites than the reference catalyst, and exhibited better coke selectivity. The prepared catalyst had the optimum isomerization and aromatization performance. The olefin content in the cracked gasoline obtained over this catalyst was reduced by 5.05 percentage points with the research octane number of gasoline increased by 0.5 units.展开更多
文摘In the tropics, lowland rice cultivation is often confronted with the problem of iron toxicity. The solution proposed by research in general is the use of industrial silicon. However, the high cost of industrial silicon limits its adoption by farmers. A study was carried out in Zakogbeu;Center-West of Côte d’Ivoire, to assess the potential of kaolin to mitigate the effect of this soil constraint on the root of the rice plant. Five kaolin-based treatments were analyzed (T<sub>0 </sub>= 0 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>1</sub> = 366 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>2</sub> = 736 kg kaolin ha<sup>−</sup><sup>1</sup>, T<sub>3</sub> = 1097 kg kaolin ha<sup>−</sup><sup>1</sup> and T<sub>4</sub> = 1465 kg kaolin ha<sup>−</sup><sup>1</sup> are 0, 200, 400, 600 and 800 kg SiO<sub>2</sub> ha<sup>−</sup><sup>1</sup>) in a device in complete random blocks, with 5 repetitions. The results obtained show that kaolin supply increases the length of the root tissue as well as the number of branching of the root of the rice plant. Root tissue increased from 10 cm with T<sub>0</sub> treatment to more than 15 cm with treatment T<sub>4</sub>. The microscopic observation of the roots shows that in the treatment T<sub>0</sub>, the roots present only primary ramifications and the tertiary and quaternary ramifications are observed with the treatments T<sub>3</sub> and T<sub>4</sub>. The contribution of kaolin is an alternative to inhibit the effect of iron toxicity on the rice plant root development in iron toxicity condition.
文摘In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy efficiency of various industrial applications by minimizing heat loss and temperature control. These panels function as silent protectors, aiding in reducing energy consumption and making things more sustainable and better for the environment. This is where composite materials come in;they are known for their lightweight nature, high strength-to-weight ratio, and excellent thermal insulation properties and have gained significant attention. Researchers are actively engaged in various studies aimed at enhancing these materials further. This research project focuses on the development of kaolin and glass fiber-reinforced composites for thermally insulating panels, to which natural strengthening materials like corn husk and bamboo fibers are added. The aim is to create cost-effective and efficient composite materials for thermal insulation applications by incorporating these components with a binder consisting of potassium silicate, hydroxide, and distilled water. This project involves conducting compression tests, bending tests, impact tests, thermal conductivity measurements, and microscopic analysis to evaluate the mechanical and thermal properties of the developed composites. The profound impact of these engineered composites on thermal insulation panels stands to revolutionize energy conservation efforts, offering a potent avenue to minimize heat loss and enhance overall energy efficiency across an array of industrial sectors.
文摘This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinations at 850<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C, to transform the kaolin to a more reactive metakaolin. Afterwards, the extremely reactive metakaolin was purge with sulphuric acid to obtain the much needed silica-alumina ratio for zeolite X synthesis. An alkaline fusion stage was then carried out to transform the metakaolin into zeolite by mixing with aqueous NaOH to form gel then allowed to stay for a duration of seven days at room temperature. The samples were then charged into a propylene container and placed in an oven at a temperature of 100<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C for the reaction to take place for 6 h. Identification of the crystalline phases by X-ray Diffraction (XRD), chemical/elemental compositions by X-ray Fluorescence (XRF)/Energy Dispersive Spectroscopic analyses (EDS), surface morphology by Scanning Electron Microscopy (SEM) and molecular vibration of units by Fourier Transform Infrared Spectrophotometry (FT-IR) were done. The results showed that the zeolite synthesized from Chokocho kaolin (CK) was more crystalline/larger with sharper peaks on both XRD and FTIR than that from Kono-Boue. This was also supported by slightly rougher surface morphology of CK over KK on SEM. XRF Si:Al ratios of 10.73 and 14.36 were obtained for KK and CK respectively. EDS results supported the XRF ratios. Sharper zeolitic characteristic O-H stretching bands at 3488 and 3755 cm<sup>-1</sup> were recorded for CK than KK. However, both results showed that zeolite X have been produced from both Kono-Boue and Chokocho kaolin clays respectively.
文摘The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron microscopy, tensile tests, and thermal resistance). The results obtained showed that kaolin, an inert material, prevents the starch from losing its granular structure and to solubilize during the heating, generating plastic films of low Young’s modulus (7 MPa). On the other hand, metakaolin, an amorphous and dehydroxylated material obtained after heating of kaolin at 700°C for 1 hour, substantially improves the thermomechanical properties of the plastic films. The Young’s modulus increases from 19 MPa to 25 MPa while the thermal resistance increases from 90°C to 120°C. This was attributed to good dispersion of the metakaolin in the polymer matrix after the loss of the granular structure of the starch during heating.
基金Project supported by Chinese Possteoctoral Fund Shandong Natural Science Fund No.93E0175
文摘This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system.
文摘Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃~550℃ in order to obtain suitable liquid fuels.The dependencies between process temperatures,types of catalyst,feed compositions and product yields of the obtained fuel fractions were found.It was observed that up to 450℃ thermal cracking temperature,the major product of pyrolysis was liquid oil and the major product at other higher temperatures(475℃~550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃.Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction.Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil.Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature.The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively.On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.
基金supported by Beijing Natural Science Foundation (Grant No.2093043)the National Natural Science Foundation of China (Grant No.20606038)
文摘Well-crystallized high-silica NaY zeolites (Si/Al〉2.5) were prepared from a reaction mixture consisting of metakaolin, sodium silicate solution and seed solution via optimization of the mixture composition and reaction conditions. The transformation from kaolin to high-silica NaY zeolite was confirmed by XRD, SEM and IR techniques. Subsequently, the influence of synthesis parameters, i.e. initial SIO2/Al2O3, initial Na2O/SiO2, initial H2O/SiO2, aging time of the seed solution, crystallization temperature and crystallization time, on the NaY growth was investigated in terms of crystallinity and Si/Al ratio. The results showed that the effects of initial SiO2/Al2O3, initial Na2O/SiO2 and initial H2O/ SiO2 on the crystaIlinity and Si/Al ratio of NaY zeolite are similar to those observed in the conventional syntheses of NaY zeolites only using sodium silicate solution as silicon source. However, due to the use of metakaolin as the main silicon and aluminum sources in the present study, a long crystallization induction period of 20 h was achieved, which can be attributed to the dissolution of metakaolin. In addition, different from the conventional syntheses of zeolite NaY, pure NaY zeolites (i.e. without NaP zeolite impurity) were still obtained even at 120℃ because of the use of a large quantity of seed solution (23 wt%) in the reaction mixture. As the aging time of the seed solution increased from 3.5 h to 22 h, the relative crystallinity of the NaY zeolite first increased sharply and then reached a plateau, while the Si/Al ratio first increased rapidly up to a maximum value of 2.75 corresponding to an aging time of 6.5 h, and then decreased sharply with the aging time.
文摘NaY zeolites were in-situ synthesized from coal-based kaolin via thehydrothermal method. The effects of various factors on the structure of the samples were extensivelyinvestigated. The samples were characterized by N_2 adsorption, XRD, IR and DTG-DTA methods, andthe results show that the crystallization temperature and amount of added water play an importantrole in the formation of the zeolite structure. The 4A and P zeolites are the competitive phasepresent in the resulting product. However, NaY zeolites with a higher relative crystallinity,excluding impure crystals and the well hydrothermal stability, can be synthesized from coal-basedkaolin. These zeolites possess a larger surface area and a narrow pore size distribution, and thismeans that optimization of this process might result in a commercial route to synthesize NaYzeolites from coal-based kaolin.
基金Projects(41330641,41272311,41202192)supported by the National Natural Science Foundation of ChinaProject(BK2010060)supported by the Key Project of Natural Science Foundation of Jiangsu Province,China
文摘Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments.Oil contents(mass fraction) of 4%,8%,12%,16% and 20% were selected to represent different contamination degrees,and the soil specimens were manually prepared through mixing and static compaction method.Initial water content and dry density of the test kaolin clay were controlled at 10% and 1.58 g/cm^3,respectively.Test results indicate that since part of the diesel oil will be released from soil by evaporation,the real water content should be derived through calibration of the quasi water content obtained by traditional test method.As contamination degree of the kaolin clay increases,both liquid limit and plastic limit decrease,but there's only a slight increase for plasticity index.Swelling pressure of contaminated kaolin clay under confined condition will be lowered when oil-content gets higher.Unconfined compressive strength(UCS) of the oil-contaminated kaolin clay is influenced by not only oil content but also curing period.Increase of contamination degree will continually lower UCS of the kaolin clay specimen.In addition,electrical resistivity of the contaminated kaolin clay with given water content decreases with the increase of oil content.However,soil resistivity is in good relationship with oil content and UCS.Finally,oil content of 8% is found to be a critical value for engineering property of kaolin clay to transit from water-dominated towards oil-dominated characteristics.
基金financially supported by Zhejiang Natural Science Foundation(No.Y1080393)Opening Foundation of State Key Laboratory of Clean Energy Utilization(No.ZJUEDU2012001)
文摘Calcination and acid leaching of coal kaolin were studied to determine an effective and economical preparation method of calcined kaolin. Thermogravimetric-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD) demonstrated that 900&#176;C was the suitable temperature for the calcination. Leaching tests showed that hydrochloric acid was more effective for iron dissolution from raw coal kaolin (RCK), whereas oxalic acid was more effective on iron dissolution from calcined coal kaolin (CCK). The iron dissolution from CCK was 28.78wt%, which is far less effective than the 54.86wt% of RCK under their respective optimal conditions. Through analysis by using M?ssbauer spectroscopy, it is detected that nearly all of the structural ferrous ions in RCK were removed by hydrochloric acid. However, iron sites in CCK changed slightly by oxalic acid leaching because nearly all ferrous ions were transformed into ferric species after firing at 900&#176;C. It can be concluded that it is difficult to remove the structural ferric ions and ferric oxides evolved from the structural ferrous ions. Thus, iron removal by acids should be conducted prior to calcination.
基金the King Abdulaziz City Science and Technology (KACST) for funding this study through collaboration between KACST-Universiti Malaysia Perlis (UniMAP)
文摘Kaolin geopolymers were produced by the alkali-activation of kaolin with an activator solution (a mixture of NaOH and sodium silicate solutions). The NaOH solution was prepared at a concentration of 6-14 mol/L and was mixed with the sodium silicate solution at a Na2SiO3/NaOH mass ratio of 0.24 to prepare an activator solution. The kaolin-to-activator solution mass ratio used was 0.80. This paper aimed to analyze the effect of NaOH concentration on the compressive strength of kaolin geopolymers at 80℃ for 1, 2, and 3 d. Kaolin geopolymers were stable in water, and strength results showed that the kaolin binder had adequate compressive strength with 12 mol/L of NaOH concentration. When the NaOH concentration increased, the SiO2/Na20 decreased. The increased Na20 content enhanced the dissolution of kaolin as shown in X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses. However, excess in this content was not beneficial for the strength development of kaolin geopolymers. In addition, there was the formation of more geopolymeric gel in 12 mol/L samples. The XRD pattern of the samples showed a higher amorphous content and a more geopolymer bonding existed as proved by FTIR analysis.
基金Funded by the National Key Technology R&D Program of China(No.2008BAE60B06)Beijing Municipal Science&Technology Commission (No.Z080003032208015)
文摘Calcined kaolin/TiO2 composite particle material (CK/TCPM) was prepared with TiO2 coating on the surfaces of calcined kaolin particles by the mechano-chemical method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to investigate the microstructures and morphologies, respectively. The mechanism of the mechano-chemical reaction between calcined kaolin and TiO2 was studied by infrared spectra (IR). The results show that TiO2 coats evenly on the surfaces of calcined kaolin particles by Si-O-Ti and Al-O-Ti bonds on their interfaces. The hiding power and whiteness of CK/TCPM are 17.12 g/m^2 and 95.7%, respectively, presenting its similarity to TiO2 in pigment properties.
基金supported by the National Natural Science Foundation of China(No.51405002)
文摘Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.
基金Supported by the National Natural Science Foundation of China(21161140329)the National High Technology Research and Development Program of China(2015AA050502).
文摘Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different.XRD pattern of the kaolin calcined at 600°C or 900°C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100°C showed obvious peaks forγ-Al2 O3.Therefore,the nickel-based catalysts exhibited different physic-chemical properties.Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100 N CA-900 N CA-1400 N CA-600 N KA≈0 at temperatures of 350–650°C and a space velocity of 120 L·g-1·h-1.Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation.
基金financially supported by the National Natural Science Foundation of China (No.21371055)the Hunan Provincial Colleges and Universities Innovation Platform Open Fund Project (No.15K049)
文摘This paper has provided an effective method to utilize the filter residue. A Y zeolite-containing composite and a fluid catalytic cracking(FCC) catalyst had been successfully prepared by an in-situ crystallization technology using filter residue and kaolin as raw materials. The samples were characterized by XRD, FT-IR, SEM, and N_2 adsorption-desorption techniques and evaluated in a bench FCC unit. In comparison to the reference samples synthesized from single kaolin,the silica/alumina molar ratio, the external surface area, and the total pore volume of the composite increased by 16.2%,14.5%, and 16.2%, respectively. The catalyst possessed more meso-and macro-pores and more acid sites than the reference catalyst, and exhibited better coke selectivity. The prepared catalyst had the optimum isomerization and aromatization performance. The olefin content in the cracked gasoline obtained over this catalyst was reduced by 5.05 percentage points with the research octane number of gasoline increased by 0.5 units.