Ghoy , Jia Pei
(2016)
Afi Molecular Sieves Formation Templated By Imidazolium-Based Ionic Liquids Under Ionothermal And Hydrothermal Conditions.
Masters thesis, Universiti Sains Malaysia.
Abstract
Feroaluminofosfat (FeAPO-5) dan aluminofosfat (AlPO-5) yang memiliki topologi AFI masing-masing telah disintesis melalui kaedah ionotermal dan hidrotermal. Kaedah ionotermal dijalankan dengan menggunakan 1-benzil-2,3-dimetilimidazolium klorida, [bzm]Cl, sebagai agen pengarah struktur sementara kaedah hidrotermal dijalankan dengan menggunakan 1-benzil-2,3-dimetilimidazolium hidroksida ([bzm]OH), 1-propil-2,3-dimetilimidazolium hidroksida ([pm]OH) dan 3-(2,3-dihidroksipropil)-1,2-dimetilimidazolium hidroksida ([dhm]OH) sebagai agen pengarah struktur. Pembentukan FeAPO-5 di bawah keadaan ionotermal dengan menggunakan H3PO3 sebagai sumber fosforus dianalisa secara spektroskopi dan mikroskopi termasuk fenomena yang melibatkan proses induksi, nukleasi dan penghabluran. Hasil kajian menunjukkan pemerbadanan kation Fe3+ telah meningkatkan kadar penghabluran FeAPO-5. Semasa proses penghabluran, fasa perantaraan ferumaluminofosfit FeNKX-2 terbentuk sebelum transformasi kepada fasa FeAPO-5 berlaku. Peningkatan kadar penghabluran feroaluminofosfat FeAPO-5 dapat dijelaskan dengan kehadiran kation Fe3+ yang bertindak sebagai media pemindahan elektron perantaraan dan menggalakkan pembebasan kation fosforus P5+ dari takungan kation fosfit P3+ yang diperlukan untuk penghabluran FeAPO-5. Suatu mekanisme penghabluran FeAPO-5 juga dicadangkan berdasarkan hasil kajian eksperimen yang diperolehi.
Ferroaluminophosphate (FeAPO-5) and aluminophosphate (AlPO-5) molecular sieves of AFI topology have been successfully synthesized under ionothermal and hydrothermal conditions, respectively. The former approach employed 1-benzyl-2,3-dimethylimidazolium chloride ([bzm]Cl), as a structure-directing agent (SDA) while the latter used 1-benzyl-2,3-dimethylimidazolium hydroxide ([bzm]OH), 1-propyl-2,3-dimethylimidazolium hydroxide ([pm]OH) and 3-(2,3-dihydroxypropy)-1,2-dimethylimidazolium hydroxide ([dhm]OH) as the SDAs. The formation of FeAPO-5 under ionothermal condition using H3PO3 as a phosphorus source was investigated by spectroscopy and microscopy analyzes where the phenomenon involved induction, nucleation and crystallization processes. The results obtained showed that the incorporation of Fe3+ has enhanced the crystallization rate of FeAPO-5. During the crystallization process, FeNKX-2 intermediate was first obtained prior to phase transformation to FeAPO-5. The fast crystallization rate of FeAPO-5 was explained by the presence of Fe3+ as an intermediary electron-transfer medium promoting the fast release of phosphorus nutrient, P5+, from phosphite, P3+, a reservoir that required for the crystallization of FeAPO-5. A possible mechanism for the growth of FeAPO-5 crystals via new synthesis route was also proposed based on the experimental results and time-dependent studies.
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