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Synthesis and characterisation of natural hydrothermal zeolites and their catalysis in N-fixation: An experimental approach
Stockholm University, Faculty of Science, Department of Geological Sciences.
2013 (English)Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The abiotic chemistry to form the components necessary for the origin of life are thought to have emerged during the hadean eon. It is thought to be characterised by a CO2/N2 atmosphere, a shallow acidic ocean with alkaline waters in hydrothermal systems, and a basaltic ocean crust. One of the necessary components for life is bioavailable N-sources such as NH4. In this study the synthesis of three common natural zeolites was attempted. These were characterised using optical microscopy, ESEM, PXRD, FT-IR and BET. The products synthesised were two zeolites, phillipsite and analcime as well as the feldspar sanidine. These were then also synthesised with an in situ Fe2+ & Fe3+ source in alkaline conditions and the products were exposed to a post-synthesis treatment of de-aluminising and were subjected to iron substitution. Incorporating iron into the crystal structure by replacing Al. Characterisation show that analcime, phillipsite, sanidine and merlinoite were produced. All products, including those with post-synthesis treatments show the presence of Brønstedt acid sites. The surface area for iron in situ synthesised products show a trend of increasing surface area and pore area/volume when iron is incorporated into the crystal structure. Phillipsite and analcime with their iron in situ products were then used in catalysis of N-reduction using a continuous flow system and an autoclave system. The catalysis was run at pH 10 & 100°C to imitate mild hydrothermal conditions. It was seen that analcime had the highest production rate of NH4+; nevertheless, both products were able to produce NH4+ from NO3-, as well as N2. This gives a new insight into hadean hydrothermal systems and their role in production of bioavailable N-sources for the origin of life. 

Place, publisher, year, edition, pages
2013. , 49 p.
Keyword [en]
zeolite, hydrothermal, hadean, astrobiology, exobiology, early life, prebiotic
National Category
URN: urn:nbn:se:su:diva-93621OAI: diva2:647220
Available from: 2013-10-02 Created: 2013-09-10 Last updated: 2013-10-02Bibliographically approved

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