(786c) Photo-Enhanced Reactive Desulfurization Via Gold-ZnO Nanoparticles

Increasingly stringent regulations on the sulfur-content of fuels require continuous development of improved sulfur-removal technology. Technologies involving high temperature adsorptive removal of organo-sulfur impurities from raw fuel sources are widely practiced. Adsorption-based technologies that rely on metal oxides often require higher temperature to accelerate the chemical conversion, which often results in sorbent volatilization, chemical reduction, loss of sorbent surface area and physical attrition. It would be highly desirable to devise a low-temperature catalytic adsorbent, which can provide accelerated reaction together with higher capacity of metal oxides.

Here, we show that it is possible to use visible light to achieve room temperature reactive desulfurization by using gold-zinc oxide nano-heterostructures as adsorbents. In preliminary studies, we found that, when exposed to green light Au-loaded ZnO nanoparticles achieve room temperature catalytic decomposition of model organo-sulfur compounds (thioacetamide), which is accompanied by reactive transformation of zinc oxide to zinc sulfide.  Without light, the system had to be heated to 373 K to cause the desired conversion. Photo-excited hot-electrons from gold are likely responsible for this photocatalytic process. In order to shed light on this potential mechanism, we are investigating the performance of the heterostructures with different excitation wavelengths, electron/hole scavengers, and other metals. Analysis is being carried out via X-ray diffraction, mass-spectrometery, and analytical electron microscopy.  We are particularly interested in probing the possible plasmonic origin of the photocatalytic effect and synergy between the metal and oxide.