| Popis: |
The selective oxidation of methane, which is the primary component of natural gas, isone of the most important challenges in catalysis. While the search for catalysts capable of converting methane to higher value commodity chemicals and liquid fuels such as methanol has been ongoing for over a century, an industrially viable process has not yet been developed. Currently, large scale upgradation of natural gas proceeds indirectly employing high temperature conversion to syngas which is then processed to synthesise fuels and chemicals. Different catalysts are currently being studied for direct low temperature selective oxidation of methane to liquid oxygenates primarily methanol. One of the systems studied is based on gold-palladium supported nanoparticles using hydrogen peroxide. Though the catalyst was shown to be active, high wastage of hydrogen peroxide was observed along with low productivities. The work in this thesis shows the removal of support can be used to increase the activity and efficiency of the reaction. By tuning the amount of hydrogen peroxide, high productivities and selectivities were observed. Further optimisation of catalyst preparation and methane oxidation were also performed. A theoretical study based on density functional theory into interactions between metal particles, such as gold and palladium and substrates such as oxygen, hydrogen and water was also carried out to identify the active sites and reaction mechanism underway with hydrogen peroxide and these metal particles. |
