Resumen de The development of novel Yolk@Shell catalysts for the thermochemical conversion of CO2
CO2 is a plentiful feedstock for reactions that converts this waste material into a valuable source of chemicals and fuels. The current technology used in this field is complex supported metal nanoparticles, popularised by simplistic synthetic routes and reaction applicability. This morphology is highly prone to sintering, which can, in turn, cause carbon deposit formation (coke) on the surface that blocks the active sites.
A promising method to improve upon these issues is the variation of the catalytic morphology; encapsulation of the active phase to produce Yolk@Shell particles. Results from the “proof of concept” NiZnO@SiO2 material proved varied; the catalyst demonstrated impressive longevity within the dry reforming of methane, surpassing the internal comparisons by a significant margin, but deactivated. The second chapter sought to improve upon the sample homogeneity and explore their reverse water gas shift reaction performance. The NiCo@SiO2 catalysts performed admirably and suggested advanced product formation after a mass spectrometry study. This finding suggests that the Yolk@Shell structure is capable of increasing internal pressure, allowing new reaction mechanisms to occur. The third catalyst was a reimagining of a traditional catalyst (Cu/ZnO@Mo2C) in the Yolk@Shell morphology. In addition to favourable longevity and reactive selectivity, complex organic product formation was also seen, again linked to the Yolk@Shell structure. The final catalyst developed for this thesis was a preliminary study aiming to combine single-atom catalysts and the encapsulation. Catalytic testing displayed impressive CO2 conversion and longevity, with no sintering or coke. While the XRD results show that single-atom sites were not achieved, however further work could see these two structures combined successfully.
Overall, this thesis is based on synthetic development and reactive studies to produce highly effective catalysts for the thermal conversion of CO2, while remaining facile and highly resistant to deactivation. It is hoped that this work will inspire more imaginative methods of catalytic development and investigation to further the field as a whole and not just thermal CO2 utilisation.
