X-ray crystallographic analysis of ADORable zeolites and metal-organic frameworks

Zeolites--Synthesis;X-ray crystallography

Henkelis, Susan Elizabeth ; Morris, Russell Edward ; Morris, Russell Edward

University:University of St Andrews

Department:Chemistry (School of)

关键词: Zeolites--Synthesis;    X-ray crystallography;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/17923/SusanHenkelisPhDThesis.pdf?sequence=2&isAllowed=y

来源: DR-NTU

【 摘 要 】

This thesis largely focuses on the mechanistic analysis of the Assembly-Disassembly-Organisation-Reassembly (ADOR) process through a range of crystallographic techniquesincluding powder X-ray diffraction and Pair Distribution Function (PDF) analysis andsubsequent analysis using solid-state kinetics.Chapter 4 describes the development of a new standard protocol to using the ADORprocess. The protocol describes the development of a procedure used for identifying theoptimum conditions (time of reaction, temperature, acidity, etc.) for the ADOR process. Indeveloping the protocol, Ge-containing UTL zeolites were subjected to hydrolysisconditions using both water and hydrochloric acid as media, which provides anunderstanding of the effects of temperature and pH on the Disassembly (D) andOrganisation (O) steps of the process that define the potential products. Samples wereanalysed by powder X-ray diffraction to yield a time course for the reaction at each set ofconditions.Chapter 5 continues work on the ADOR process and presents the first kinetic study on thetwo most prominent steps in the process; Disassembly and Organisation. By using solid-state kinetic models, Avrami-Erofeev and its linear equivalent Sharp-Hancock, thedependence on temperature and presence of liquid water was investigated and the activationenergy of the rearrangement process quantified. Work on the rearrangement step aimed tounderstand where the silica species intercalates from and which material formed as thekinetic and thermodynamic product from the reaction.Chapter 6 describes a study into the Disassembly and Organisation steps of the ADORprocess through in situ Pair Distribution Function (PDF) analysis. This hopes to shed lighton the selectivity of the ADOR process in different media and the mechanism by which thedouble-four-ring (d4r) breakdown.On a different note, Chapter 7 describes the refinement of synthesis conditions used toprepare poly-crystalline CPO-27-M (MOF-74) with lower concentrations of base and at lowtemperature. Refinement of the synthesis of single crystal CPO-27-Mg, -Zn and UTSA-74was undertaken and the necessary components to forming large single crystals understood.