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Hydrothermal stability of high silica zeolites

หน่วยงาน Edinburgh Research Archive, United Kingdom

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ชื่อเรื่อง : Hydrothermal stability of high silica zeolites
นักวิจัย : Young, David
คำค้น : Zeolites , Molecular sieves , Silica
หน่วยงาน : Edinburgh Research Archive, United Kingdom
ผู้ร่วมงาน : Lowe, B. M. , Science and Engineering Research Council
ปีพิมพ์ : 2531
อ้างอิง : http://hdl.handle.net/1842/9864
ที่มา : -
ความเชี่ยวชาญ : -
ความสัมพันธ์ : -
ขอบเขตของเนื้อหา : -
บทคัดย่อ/คำอธิบาย :

This thesis concerns the hydrothermal stability of two zeolite molecular sieves with the MFI structure, ZSM-5 and its 'aluminium free' form silicalite. Silicalite was synthesised from low pH alkali metal free aqueous gels at 95°C and characterised by XRD, SEM, DTA and TG. ZSM-5 was crystallised from similar reaction mixtures but with the addition of aluminium salts. It was found that the incorporation of aluminium into the ZSM-5 framework was favoured by higher reaction temperatures (l50°C) and the use of aluminium nitrate. Solubilities were measured for silicalite, ZSM-5, ZSM-11, ZSM-39, ZSM-48 and EU-4 at temperatures up to 95°C. The solubilities were influenced by framework structure, the presence of template within the zeolite channels and the aluminium content of the lattice. Solubility measurements over a range of liquid/solid ratios showed that calcined silicalite was contaminated with about 1% amorphous silica. Treatment with liquid water over the temperature range 95 to 230°C was used to remove amorphous silica and alnminosilicate species from silicalite and ZSM-5. This hydrothermal treatment had many other effects on the properties of these materials. The water uptake, orthorhombic to monoclinic symmetry transition, framework Si/Al ratio and thermal properties were all affected. SEM showed that the inside of the silicalite crystals was more soluble than the outer surface. The use of hydrothermally treated H-ZSM-5 as a catalyst for but-1-ene isomerisation showed that the treatment could have a marked effect on catalytic behaviour, and particularly on product selectivity.

บรรณานุกรม :
Young, David . (2531). Hydrothermal stability of high silica zeolites.
    กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom .
Young, David . 2531. "Hydrothermal stability of high silica zeolites".
    กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom .
Young, David . "Hydrothermal stability of high silica zeolites."
    กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom , 2531. Print.
Young, David . Hydrothermal stability of high silica zeolites. กรุงเทพมหานคร : Edinburgh Research Archive, United Kingdom ; 2531.