Subject Area物理化学
Ultra-deep Desulfurization of Fuels by Emulsion Catalysis
Li C(李灿)
Conference Name5th International Conference on Environmental Catalysis
Conference Date2008-8-31
Conference Place
Funding Organization英国女王大学
AbstractIntroduction Much attention has been paid to the deep desulfurization and even ultra-deep desulfurization of fuel oils due to more stringent environmental regulations for environmental concerns. Although hydrodesulfurization (HDS) is highly efficient in removing thiols, sulfides, and disulfides, it is difficult to reduce refractory sulfur-containing compounds such as dibenzothiophene (DBT) and its derivatives, especially 4, 6-dimethydibenzothiophene (4, 6-DMDBT), to an ultra-low level. Therefore, it is highly desirable to develop non-HDS methods to meet the demands of producing clean diesel1 with an extremely low concentration of sulfur-containing compounds. Among them, oxidative desulfurization combined with extraction is considered to be one of the most promising processes. In this lecture, we report that amphiphilic catalysts assembled in an emulsion in diesel, could selectively oxidize sulfur-containing compounds into their corresponding sulfones by using an approximately stoichiometric amount of H2O2 as the oxidant. The sulfones can be readily separated from the diesel using an extractant and ultra-deep desulfurization of diesel can be achieved. Results and discussion We have developed a series of emulsion catalysts, which are composed of the quaternary ammonium salt cations and heteropolymetalate anions, such as Q3[PW12O40] and Q4[H2NaPW10O36]. The catalysts are assembled at the interface of two immiscible liquids and form emulsion droplets. These emulsion droplets act as a homogeneous catalyst to efficiently oxidize the sulfur-containing molecules to sulfones in diesel. As an example, the catalyst, [C18H37N(CH3)3]4[H2NaPW10O36], in the W/O emulsion system exhibits very high catalytic activity such that all sulfur-containing compounds in either model or real diesel can be selectively oxidized into their corresponding sulfones using hydrogen peroxide as an oxidant. The sulfur level of a prehydrotreated diesel can be lowered from 500 to 0.1 ppm after oxidation and then extraction, whereas the sulfur level of a straight-run diesel can be decreased from 6000 to 30 ppm after oxidation and extraction. The catalysts demonstrate high performance, i.e., 96% efficiency of H2O2, and ~100% selectivity to sulfones.[1-3] Conclusion and perspectives The amphiphilic catalysts assembled at the interface of emulsion droplets, which can be separated easily from reaction systems, shows high selectivity and activity in the oxidation of sulfur-containing molecules to sulfone. The sulfur level in diesel is reduced to only a few ppms from several hundred ppms using the oxidation/extraction approach. This approach is actually an environmentally friendly strategy not only effective for removing the sulfur-containing compounds from fuels but also potentially useful for the organic synthesis using water as the solvent. Our preliminary results demonstrated that the emulsion catalysis can significantly enhance the catalytic performance of selective oxidation of alcohol, epoxidation of olefins and chiral Aldole reactions[4-6].
Document Type会议论文
Corresponding AuthorLi C(李灿)
Recommended Citation
GB/T 7714
Li C. Ultra-deep Desulfurization of Fuels by Emulsion Catalysis[C],2008:PL3/2.
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