TitleOxidative desulfurization of dibenzothiophene with tert-butyl peroxide in a carbon nanotube supported corona discharge microreactor
Publication TypeThesis
Year of Publication2010
AuthorsCaple, KR
UniversityOregon State University
CityCorvallis, Or.
Thesis TypeDissertation

Sulfur content in fuel is an increasingly important environmental concern. A commonly used method for the removal of sulfur bearing species from fuel is through hydrodesulphurization. However, due to the implementation of Ultra-Low Diesel Sulfur (ULDS), deeper desulphurization techniques must be explored. In this study, a single phase oxidative desulphurization microreactor is crafted for this purpose. The proposed microreactor is built around the concept of corona discharge. The corona is created through a significant potential difference between a carbon nanotube supported emitter electrode and a stainless steel collector electrode. The current that passes through the two electrodes acts as a catalytic agent for the oxidation of the sulfur bearing species. Dibenzothiophene and tert-butyl peroxide are mixed with decane into two separate feed streams. The two feed streams are sent through a micromixer and continue into the reactor. The reactor system is activated and current flows within the reaction volume between the two electrodes. The proposed reaction mechanism is similar to that of the photooxidation of dibenzothiophene in which the peroxide is cleaved by the electrical energy and subsequently reacts with the sulfur to form its oxides, sulfoxides and sulfones, respectively. Due to the high polarity of these products, they are easily extracted from the fuel stream. Experiments testing the capabilities of the proposed reactor include varying the applied current to the reaction volume, inlet concentrations of both the fuel and oxidant streams, the reactor volume residence time, the post-reactor volume residence time, and the effect of aging upon the oxidant stream. This proposed microreactor was successfully crafted and the corona successfully discharged between the emitter and collector electrodes. Testing of the reactor's capabilities suggest that the proposed oxidation mechanism is not strictly duplicated within this microreactor system. For this first generation reactor system, a maximum conversion of 68% of dibenzothiophene to its sulfoxide and sulfone has been found. Dissolved oxygen in decane was also found to be a sufficient oxidant source to initiate the oxidative reaction and has been shown to continue to be an oxidant source even in the presence of peroxide.