Synthesis and characterization of Na-P1 (GIS) zeolite using a kaolinitic rock (original) (raw)
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Synthesis and characterization of Na-X, Na-A, Hydroxisodalite and Na-P zeolites from metakaolinite
D. NOVEMBRE, B. DI SABATINO, D. GIMENO, C. PACE (2011) Synthesis and characterization of Na-X, Na-A, Hydroxisodalite and Na-P zeolites from metakaolinite. Clay Minerals, 46: 336-354, 2011
The present work deals with the hydrothermal synthesis of Na zeolites (Na-A, Na-X and Na-P) and hydroxysodalite using kaolinite calcined at 650ºC as starting material. The focus was on definition of the most favourable conditions for the synthesis of zeolite Na-A and Na-X from metakaolin in order to economize on both energy (i.e. synthesis temperatures) and reaction time and to enlarge the field of pure and isolated synthesized phases. Metakaolin was mixed with calculated amounts of NaOH solution and sodium silicate and five sets of experiments were carried out at ambient pressure and 6880.1ºC varying the SiO2/Al2O3 ratio from 2.2 to 7. Optimal conditions for crystallization of Na-A zeolite from kaolinite were reached with a SiO2/Al2O3 ratio of 2.2 plus 4 M NaOH without adding sodium silicate; transformation into hydroxysodalite develops after ~8 h. For SiO2/Al2O3 ratios between 4 and 7, crystallization of the separate Na-X zeolite phase could be achieved and transformation into Na-P and hydroxysodalite occurred after 382 h and 190 h, respectively. For SiO2/Al2O3 ratios between 5 and 6, transformation of metakaolin into Na-X plus Na-A, hydroxysodalite and Na-P occurred, and the field within which Na-A and Na-X zeolite exists overlapped that of the other zeolites. The products of synthesis were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma optical emission spectrometry (ICP-OES), infrared spectroscopy (IR) and thermal analyses (TG-DTG-DTA). Obtaining pure Na-A and Na-X zeolite from kaolinite treated at low metakaolinitization temperature (650ºC) and low hydrothermal synthesis temperature (68ºC) represents a considerable economic advantage in terms of both energy and time.
AB ST R ACT : The present work deals with the hydrothermal synthesis of Na zeolites (Na-A, Na-X and Na-P) and hydroxysodalite using kaolinite calcined at 650ºC as starting material. The focus was on definition of the most favourable conditions for the synthesis of zeolite Na-A and Na-X from metakaolin in order to economize on both energy (i.e. synthesis temperatures) and reaction time and to enlarge the field of pure and isolated synthesized phases. Metakaolin was mixed with calculated amounts of NaOH solution and sodium silicate and five sets of experiments were carried out at ambient pressure and 68Ô0.1ºC varying the SiO 2 /Al 2 O 3 ratio from 2.2 to 7. Optimal conditions for crystallization of Na-A zeolite from kaolinite were reached with a SiO 2 /Al 2 O 3 ratio of 2.2 plus 4 M NaOH without adding sodium silicate; transformation into hydroxysodalite develops after~8 h. For SiO 2 /Al 2 O 3 ratios between 4 and 7, crystallization of the separate Na-X zeolite phase could be achieved and transformation into Na-P and hydroxysodalite occurred after 382 h and 190 h, respectively. For SiO 2 /Al 2 O 3 ratios between 5 and 6, transformation of metakaolin into Na-X plus Na-A, hydroxysodalite and Na-P occurred, and the field within which Na-A and Na-X zeolite exists overlapped that of the other zeolites.
Synthesis process of zeolite P using a poorly crystallized kaolinite
2009
Poorly crystallized kaolinite KGa2 and metakaolinites derived from them were studied under hydrothermal conditions in an aqueous sodium hydroxide solution. Reaction was obtained in a specific reactor allowing a continuous agitation and pH and temperature controls. Metakaolinte were derived from heated kaolinite at 500°C and 900°C. Using kaolinite and metakaolinite obtained after heating at 500°C the main formed products were zeolite P. When metakaolinte obtained at 900°C reacted with NaOH solution zeolite A (LTA) is the first synthesized product and a prolonged treatment (72hours) leads to synthesize zeolite P. Intermediate and homogeneous phases were characterized by XRD analysis and MAS NMR spectroscopy.
Kinetics of formation of zeolite NaA [LTA] from natural kaolinites
Physics and Chemistry of Minerals, 1997
The kinetics and mechanism of hydrothermal formation of zeolite A from natural kaolinites have been studied using as starting materials two international kaolinite standards (KGa-1 and KGa-2 from Georgia, USA) exhibiting a different degree of stacking disorder. Precursors utilized for the synthesis were prepared by heating the kaolinites at 800 °C. Metakaolinite was also prepared from KGa-1 by thermal activation at 600 °C. The hydrothermal syntheses were accomplished by heating the samples in NaOH solutions at temperatures between 70 and 110 °C. The kinetic experiments were performed by time-resolved synchrotron powder diffraction in isothermal mode using a transmission geometry and an Image Plate detector. The results of the kinetic analysis are interpreted in the light of the structural state of the starting kaolinite, and of the temperature of activation of the precursor material. For kaolinite activated at high temperature the nucleation and crystallization of zeolite A is essentially independent of the defect density of the original kaolinite, and the thermal history of the precursor seems to be the main controlling parameter. The formation process of zeolite A from metakaolinite materials obtained at lower activation temperatures shows significantly faster reaction rates and lower apparent activation energies. This is again interpreted in the light of the short range inhomogeneities present in metakaolinite. As the reaction proceeds metastable zeolite A transforms into hydroxy-sodalite.
Synthesis of Zeolites from Thermally Activated Kaolinite. Some Observations on Nucleation and Growth
Clay Minerals, 1992
Depending on the preparation temperature and the origin of the raw mineral, the products obtained by thermal activation of kaolinite lead, by hydrothermal treatment with sodium hydroxide at 102~ either to zeolite 4A, or to cubic zeolite P, or to a mixture of cubic and tetragonal zeolite P. The change in the type of zeolite obtained was explained on the basis of a radical change of the zeolite nucleation process due to either the presence of soluble potassium or high silica content resulting from dehydration of muscovite (an impurity in the raw-kaolinite), or from "segregation" associated with the first step of the metakaolinite to mullite transformation. These phenomena occur at a lower calcination temperature with poorly-crystallized kaolinite, and iron in such a sample promotes a sensitive decrease in the formation rate of zeolite crystals. Such results could be used to characterize the crystallinity of kaolinites.
Synthesis and characterization of analcime (ANA) zeolite using a kaolinitic rock
Scientific Reports, 2021
Analcime is nowadays an important component in dental porcelain systems, in heterogeneous catalysis, in the nanoelectronic field, in selective adsorption and in stomatology (dental filling and prosthesis). Analcime synthesis from an impure, silica-rich kaolinite rock coming from Romana (Sassari, Italy) is here presented. A synthesis protocol is proposed that aims to make an improvement of synthesis conditions compared to the past. The hydrothermal treatment is in fact here achieved without aging times and without the use of sodium silicate or other additional silica source reported in the literature. Lower calcination temperature, synthesis temperature and crystallization time are verified in this work. The kaolin is subjected to calcination at the temperature of 650 °C and then mixed with NaOH. The experiment is performed at ambient pressure and 170 ± 0.1 °C. The degree of purity of analcime is calculated in 97.57% at 10 h. Analcime is characterized by X-ray diffraction, infrared s...
Zeolite P from kaolin via hydrothermal method
AIP Conference Proceedings, 2018
Zeolite P has been successfully synthesized from natural kaolin via two step hydrothermal process. The natural kaolin from Lampang, Thailand was studied for this research. In first hydrothermal, kaolin was mixed with sodium hydroxide solution at 200 o C for different reaction times from 3-5 hours, respectively .Sodium hydroxide and hydrochloric acid were added into the mixture to adjust their pH before they were formed into gel. Second hydrothermal process, the gel was kept of 90 o C for 3 days to obtain zeolite P. Synthesized zeolite P was characterized by X-ray diffraction (XRD) for identification the type and crystallization. Besides, the morphology was characterized by scanning electron microscopy)SEM.(The functional group was characterized by Fourier-transform infrared spectroscopy (FTIR). From this study, it was found that the increasing of reaction time in first hydrothermal activation and hydrochloric acid concentration lead to the high quality of zeolite P
NOVEMBRE,D.;DI SABATINO,B.; GIMENO,D.; GARCÍA VALLÉS,M. & MARTÍNEZ MANENT,S. (2004): Synthesis of Na-X zeolites from tripolaceous deposits (Crotone, Italy) and volcanic zeolitized rocks (Vico Volcano, Italy). Microporous and Mesoporous Materials. 75 (1-2): 1-11, 2004
Synthesis of zeolitic minerals (Na–X and HS) by the use of natural materials (naturally zeolitised alkaline volcanic rocks and ‘‘Tripoli’’) has been achieved.Synthesis was conducted at hydrothermal conditions (80 C) by the use of alkaline silicates (NaxSiyOz) and alkaline aluminates (NaxAlyOz).Chemical treatments were made on ‘‘Tripoli’’ rocks (mainly constituted by opaline silica) coming from Crotone Basin (southern Italy) in order to obtain Na2 SiO3 ÆnH2O.Volcanic pyroclastic rocks (naturally zeolitised to chabazite and phillipsite) from the Vico Administrative Province (central Italy) were treated to obtain the NaAlO2 solution. Both products were mixed to gain the gel NaAlSixOy ÆnH2O necessary for the zeolitic synthesis. Mineralogical–crystallographical–chemical and textural–physical characterisation showed that Na–X zeolite synthesis begins after 5 h and reaches its crystallisation climax at 18 h, with a broad field of existence (about 500 h) of the Na–X phase.Then Na–X is substituted by HS (Hydroxysodalite) zeolite.The characterisation shows that microtextural (scanning electron microscope images) and crystallographic values as well as other physical properties (specific surface, density) are comparable to the reputed ones for commercial zeolite.The thermal behaviour (TG-DTA) and IR response also provide consistent evidence of good achievement of Na–X zeolite synthesis.Finally, the wide (in terms of time) range of stability of Na–X zeolite seems to allow trans fer to an industrial production scale.
2021
Zeolites NaA is one of the most valuable synthetic zeolites widely used as ion-exchange material, catalysts, and adsorbents in industry. There is therefore need to adopt a more energy-efficient route for its synthesis from low-cost and sustainable raw materials. In this present work, zeolites Na-A was synthesized from natural kaolinite clays obtained from three selected regions (Ikere, Okpella and Kankara) in Nigeria. The asreceived kaolinite clays (IKclay, OKclay and KAclay) were initially beneficiated thoroughly to obtain pure powders (˂75 μm). The processed kaolinite clay powders were then subjected to heating in a muffle furnace at 850C for 3 h at a heating rate of 10C/min to convert the kaolinite clays to their respective metakaolins. The obtained metakaolins were then reacted with NaOH solutions at varying concentrations of 3.0 and 4.0M respectively using a low temperature hydrothermal transformation to obtained Zeolites Na-A powders. The obtained zeolites were then analyzed b...
Synthesis of zeolitic minerals (Na-X and HS) by the use of natural materials (naturally zeolitised alkaline volcanic rocks and ''Tripoli'') has been achieved. Synthesis was conducted at hydrothermal conditions (80°C) by the use of alkaline silicates (Na x Si y O z ) and alkaline aluminates (Na x Al y O z ). Chemical treatments were made on ''Tripoli'' rocks (mainly constituted by opaline silica) coming from Crotone Basin (southern Italy) in order to obtain Na 2 SiO 3 AE nH 2 O. Volcanic pyroclastic rocks (naturally zeolitised to chabazite and phillipsite) from the Vico Administrative Province (central Italy) were treated to obtain the NaAlO 2 solution.