Vol.1 No.3 2009

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Research paper : Development of highly-active hydrodesulfurization catalyst for sulfur-free diesel production (Y. Yoshimura et al.)−168 Synthesiology - English edition Vol.1 No.3 (2009) expectations for high-performance catalysts are rising. Therefore, first we have described diesel hydrodesulfurization methods and revised the text to clarify the role of catalyst technology in hydrodesulfurization.2 Technological goal for gasoline desulfurizationComment (Koichi Mizuno)In the Future Plans section, there is a statement that you would like to apply the developed technology to the selective hydrodesulfurization of gasoline. I understand that the target of this statement requires both control of the hydrogenation of olefins as well as improvement of hydrodesulfurization performance. It is not particularly emphasized, however, that catalysts that allow the control of hydrogenation as well as the improvement of hydrodesulfurization have never been explored and are a challenging technology. For the readers’ better understanding, I wonder whether you could elaborate on why the technology is challenging and how it can be turned into reality.Answer (Yuji Yoshimura)The main blending stock of regular gasoline is high-octane FCC gasoline obtained by the fluid catalytic cracking of heavy oil. Most of the sulfur content in regular gasoline comes from FCC gasoline, and hydrodesulfurization technology is therefore required to both reduce sulfur in FCC gasoline and maintain the high octane number. In order to improve the hydrodesulfurization selectivity of FCC gasoline, studies are mainly being conducted on the control of hydrogenation of olefins. These include the study of a method of controlling the hydrogenation and isomerization of olefins due to the movement of double bonds in olefins by controlling the acidity of the catalyst support [10], thereby weakening the adsorption of basic olefins. However, most of the conventional desulfurization catalysts contain the Type-I Co-Mo-S phase (Fig. 4), and are susceptible to hydrogen activation and the hydrogenation of double bonds even in the presence of hydrogen sulfide. Therefore, there is presumably a limit to (14)−control of the hydrogenation of olefins. The hydrodesulfurization selectivity of FCC gasoline is expected to further improve if desulfurization catalysts contain only the Type-II Co-Mo-S phase (or the Ni-Mo-S phase) and, in addition, if hydrodesulfurization activity per sulfur coordinatively unsaturated site can be improved and the solid acidity of the support can be optimized. We plan to apply the preparation method for the developed diesel fuel hydrodesulfurization catalyst to the production of selective hydrodesulfurization catalysts for FCC gasoline to develop applications for the developed technology.3 Future plans for fuel refining technologyQuestion (Koichi Mizuno)I understand that the results of your research on catalyst technology are intended to be used for hydrodesulfurizing diesel fuel and will be applied to the desulfurization of gasoline. Do you have a plan to develop other applications?Answer (Yuji Yoshimura)There are rapidly increasing expectations for biofuels (in the future, biofuels based on non-food biomass) arising from the need for diversification and secure supply of transportation fuels due to soaring oil prices, as well as compliance with the Kyoto Protocol. Expectations are increasing for new fuel production technologies, including hydrocarbon production using a hydrodeoxygenation catalyst technology, such as from Jatropha, a non-food oil crop, and hydrocarbon fuel production using a hydrodeoxygenation catalyst technology for pyrolysis oils (bio-oils) produced by the thermochemical conversion of biomass residue. In these reaction systems, the hydrogenation deoxidation reaction is the main reaction accompanied by the breaking of C-O bonds, unlike the hydrodesulfurization reaction accompanied by the breaking of C-S bonds. These two reactions have a similarity in the mechanism of heteroatom removal over a solid catalyst. We plan to take on the challenge of developing production technology for these new biofuels by improving the developed hydrodesulfurization catalyst.

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