Sökning: "acidity"
Visar resultat 11 - 15 av 103 avhandlingar innehållade ordet acidity.
11. Tuned acidity in zeotypes: A descriptor to unravel the direct conversion of methane to methanol
Sammanfattning : The catalyst's acidity is crucial in countless chemical reactions, and thus to tune this parameter means to take the lead on the desired catalytic reaction. Therefore, it is not surprising that zeolites have been used since decades as catalysts for their outstanding properties of solid acids. LÄS MER
12. What are the effects of natural versus human-caused acidity on stream species diversity and ecosystem functioning?
Sammanfattning : Human activities have caused acidification of freshwater systems on a large scale resulting in reduced species diversity and ecological functioning in many lakes and streams. However, many naturally acidic freshwater systems have also been found, for instance in northern Sweden. LÄS MER
13. Nitrous Oxide Formation over Zeolite-based Catalysts during Ammonia-SCR: The Effect of Framework Structure, Acidity, and Copper Content
Sammanfattning : The emission control of anthropogenic nitrous oxide (N2O), a by-product formed through fossil- and renewable fuel combustion, agricultural activities, and industrial chemical processes, has attracted large considerations due to its substantial contribution in global warming and ozone layer depletion. Selective catalytic reduction with ammonia (NH3-SCR) is the most prevailing technology for the abatement of nitrogen oxides (NOx) in the exhaust gases from lean-burn processes, with the possible formation of N2O. LÄS MER
14. Partial Oxidation of Methane over Functionalised Zeolites and Zeotypes
Sammanfattning : Partial oxidation of methane to methanol is an industrially important process that allows natural gas and biogas to be utilised for methanol-based production of chemicals or converted to liquid methanol fuel, which make transportation more facile. In this thesis, the activity for partial oxidation of methane to methanol over copper functionalised zeolites and silica supported copper is investigated using a three-step quasi-catalytic approach including catalyst activation, methane reaction and methanol extraction by water. LÄS MER
15. Evolutionary implications of acidification: a frog’s eye view
Sammanfattning : Understanding the diversity of life is one of the main aims of evolutionary biology, and requires knowledge of the occurrence and causes of adaptive genetic differentiation among geographically distinct populations. Environmental stress caused by acidity may cause strong directional selection in natural populations, but is little explored from an evolutionary perspective. LÄS MER
