Ionothermal synthesis of metal aluminophosphates

Molecular sieves--Synthesis--Technique;Aluminium compounds--Synthesis--Technique;Phosphates

Musa, Mazlina ; Morris, Russell Edward ; Morris, Russell Edward

University:University of St Andrews

Department:Chemistry (School of)

关键词: Molecular sieves--Synthesis--Technique;    Aluminium compounds--Synthesis--Technique;    Phosphates;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/4483/MazlinaMusaPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

The aim of this thesis was to synthesise CoAPO-34 and FeAPO-34 using ionothermal synthesisin the presence of organic amines. Using this method provides an alternative route to preparesuch materials under low pressure instead of the higher pressure associated with hydrothermalor solvothermal synthesis. Both materials have chabazite (CHA) topology and they are known toact as catalysts.CoAPO-34 was ionothermally prepared using 1-ethyl-3-methylimidazolium bromide (EMIMBr) inpresence of 1, 6-hexadiamine (HDA). This study has found that when the synthesis was carriedout without HDA, AlPO-11 was preferentially obtained instead of CoAPO-34. Broad line signalswhich appear between 2000 to 5000 ppm in both spin-echo ³¹P NMR spectra of as-synthesisedand calcined CoAPO-34 confirm that the Co²⁺ ions have been successfully incorporated withinthe framework of the material.FeAPO-34 was synthesised under ionothermal conditions using 1-ethyl-3-methylimidazoliumchloride in the presence of ethylenediamine (EDA). In the absence of EDA, the synthesis hasproduced AlPO-34 instead of FeAPO-34. Broad line signals that appear between 1000 to14000 ppm in spin-echo ³¹P NMR spectra of both as-synthesised and calcined FeAPO-34 aredirect evidence of isomorphous substitution of framework aluminum by Fe(II) or Fe(III).Another aim of this study was to explore the ionothermal synthesis of copper containingaluminophoshate of DNL-1 (Cu/DNL-1). This material was attractive to explore because itcontains 20 ring extra-large pores and Cu(I) species in the channels of the framework,potentially giving material the ability to simultaneous store NO and to generate NO from NO₂⁻ anions.Cu/DNL-1 was successfully prepared under ionothermal conditions using EMIMBr and HDA.Without HDA in the synthesis, AlPO-11 was obtained. In this material, copper ions were notincorporated in the Cu/DNL-1 skeleton framework. This was confirmed by absence of broadlinesignal at >500 ppm in spin-echo ³¹P NMR spectrum of the sample. The copper ions areexpected to be present as extra-framework cations. Extra-framework Cu(I) species that wereformed by high temperature calcination of Cu/DNL-1 are active to produce NO from NO₂⁻. Therefore, the calcined Cu/DNL-1 can be used to simultaneously store and produce NO fromnitrite. This has the potential to significantly extend the lifetime of gas delivery in the material toprevent thrombus formation.