![]() ![]() Das Ziel dieser Arbeit war das Aufstellen von Struktur-Eigenschaftsbeziehungen. Show moreĭie Münzmetalle Kupfer, Silber und Gold wurden auf SBA-15 geträgert und als Modell-katalysatoren für die selektive Oxidation von Propen vorgestellt. A linear correlation between metal loading, hence, particle size and propylene oxide selectivity was determined for CuO/SBA-15, Ag/SBA-15, and Au/SBA-15 samples. CuO/SBA-15 and Ag/SBA-15 samples oxidized propene to propylene oxide with molecular oxygen while Au/SBA-15 samples were solely able to form propylene oxide when hydrogen is added to the gas mixture. Conversely, Au/SBA-15 samples exhibited high acrolein selectivity but low propene reaction rate. Catalytic testing exhibited highest activity but lowest acrolein selectivity for Ag/SBA-15 samples among the supported coinage metals. DR-UV-Vis spectra of Ag/SBA-15 and Au/SBA-15 samples exhibited features corresponding to surface plasmonic resonance of silver and gold nanoparticles, respectively. Ag/SBA-15 samples showed crystalline silver for high silver loadings while crystalline gold was found for various gold loadings. Silver and especially gold nanoparticles had increased particle size compared to those of copper. In the second part of this work silver and gold nanoparticles supported on SBA-15 were synthesized and analyzed analogous to CuO/SBA-15 samples. While acrolein selectivity was largely similar for tested copper catalysts selectivity towards propylene oxide increased with particle size and the amount of bridging oxygen atoms. Investigations on catalytic performance exhibited a correlation between propene reaction rate and the amount of structural motifs corresponding to Cu2O formed during heating up the samples. Additionally, thermal pretreatment was conducted to modify structural properties. In situ DR-UV-Vis and X-ray absorption spectroscopy were implemented to elucidate structure function relationships. Increasing the copper loading resulted in an increased particle size. X-ray absorption and DR-UV-Vis spectroscopy exhibited copper oxide species comprised of units with Cu2+ in a distorted octahedral configuration. Structural characterization by N2 physisorption, X-ray diffraction, and electron microscopy revealed well dispersed copper oxide particles with a narrow particle size distribution. In the first part of this work copper oxide particles supported on nanostructured silica SBA-15 were synthesized with varying copper loadings. Structural evolution and catalytic activity were investigated during selective oxidation of propene focusing on product distribution of nucleophilic and electrophilic oxidation. The objective of this work was elucidating structure function correlations. Coinage metals comprising copper, silver, and gold supported on SBA-15 were prepared and introduced as model catalysts in propene oxidation. ![]()
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