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Author: search.filters.author.Tanwongwan, WorapakSubject: search.filters.subject.Hydrothermal

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    Combination of natural silica and alumina sources for synthesis of MCM-22 zeolite
    (2023-08-01)
    Tanwongwan, Worapak
    ;
    Chollacoop, Nuwong
    ;
    Faungnawakij, Kajornsak
    ;
    Assabumrungrat, Suttichai
    ;
    Nakhanivej, Puritut
    Zeolite has become a promising material that can potentially play a pivotal role in resolving environmental crises. Among zeolite families, MCM-22 zeolite shows outstanding intrinsic properties associated with the topology and porous structure, offering ion-exchange advantages for catalytic activity processes. The synthesis of MCM-22 zeolite becomes challenging when concerning the cost and catalytic performance. To overcome this bottleneck, we demonstrate a sustainable route of a hydrothermal process using natural resources as starting materials. Rice husk from agricultural waste was used as a silica source while natural clays (kaolin and bentonite) were applied as alumina sources. The products from natural sources were compared with the use of commercial starting materials, e.g., NaAlO<inf>2</inf> (for alumina) and Na<inf>2</inf>SiO<inf>3</inf> and TEOS (for silica), in points of crystal, compositional, and morphological views. We showed that the high purity of MCM-22 zeolite can be obtained from rice husk silica (RHS) and aluminosilicate gel (ASG) extracted from kaolin, while the use of ASG extracted from bentonite tended to be unsuitable to generate the zeolite formation. We also studied the effects of reaction time and the ratio of RHS/ASG on the crystallinity and surface area of MCM-22. The architecture and acidity of an optimal product were explored by Nuclear magnetic resonance spectroscopy and Temperature-programmed desorption of ammonia, demonstrating the success of achieving well acidity.
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    Synthesis of zeolite x from bentonite via hydrothermal method
    (2020-01-01)
    Srilai, Suphada
    ;
    Tanwongwan, Worapak
    ;
    Onpecth, Kobchai
    ;
    Wongkitikun, Thanapat
    ;
    Panpiemrasda, Kollayut
    Zeolite X were successfully synthesized from bentonite from Lopburi province, in Thailand using the two-step of hydrothermal method under optimum condition without calcination. The first step of hydrothermal were obtained at 200 ℃ for 3 h to remove unreacted impurity minerals such as quartz and muscovite. The secondary step of hydrothermal were obtained at 90 ℃ for 120 h for synthesis of zeolite X. The characterization of zeolite X were examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (FT-IR), respectively. The crystal structure of product was determined as zeolite X by XRD. The morphology of SEM images for zeolite X is octahedral shape. FTIR spectra are in accordance with the other characterization results.
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    Influence of crystallization time for synthesis of zeolite a and zeolite x from natural kaolin
    (2019-01-01)
    Srilai, Suphada
    ;
    Tanwongwan, Worapak
    ;
    Onpecth, Kobchai
    ;
    Wongkitikun, Thanapat
    ;
    Panomsuwan, Gasidit
    Zeolite A and zeolite X were successfully synthesized from natural kaolin from Lampang province using calcination and a two-step hydrothermal method. First, metakaolin was obtained by calcining the kaolin at 700 °C for 2 h. Hydrothermal experiments can be separated into two types, being high temperature and short time or lower temperature long time. For high temperature hydrothermal treatment, metakaolin was mixed with NaOH to form hydrous sodium aluminosilicate. This was dissolved in dilute HCl. After filtration, the pH was adjusted with deionized water to pH = 7. This formed an amorphous aluminosilicate gel. For low temperature and longtime hydrothermal treatment aluminosilicate gel was mixed with NaOH to form zeolite A and zeolite X. The optimum condition for the first step in the synthesis of zeolite A is high temperature and short time of hydrothermal treatment with NaOH 8 M at 200 °C for 3 hours. This is followed by low temperature and longtime of hydrothermal treatment with NaOH 1 M carried out at 90 °C for 72 hours. The optimum conditions for the first step of synthesis of zeolite X is the high temperature, short time hydrothermal treatment with NaOH 8 M at 200 °C for 3 hours and low temperature, longtime hydrothermal treatment with NaOH 1 M at 90 °C for 120 hours. The characterizations of zeolite A and zeolite X were carried out by x-ray diffraction (XRD), scanning electron microscopy (SEM), and infrared spectroscopy (FT-IR).