Many aspects of the desulfurization of trisulfides have been investigated. Efforts directed toward the syntheses of cyclic trisulfides provided mixtures of oligomers or the corresponding disulfide. Radiochemically labelled trisulfides and an optically active trisulfide have been desulfurized by a variety of phosphines. Triarylphosphines preferentially removed the central sulfur atom under all conditions, while tris(dialkylamino)phosphines exhibited preferential terminal sulfur removal in low polarity solvent with a trend to increased central sulfur removal with increased solvent polarity. Exchange phenomena were examined and a mechanistic rationalization presented. Desulfurization by triarylphosphines was concluded to proceed by the rate-determining decomposition of a phosphonium salt to form products, while desulfurization by tris(dialkylamino)phosphines was considered to have phosphonium salt formation as the rate-determining step. / The reaction of trisulfides with trialkyl phosphites to give a mixture of unsymmetrical and symmetrical disulfides has been studied. Mechanistic and synthetic aspects are described. / The spontaneous desulfurization of sulfenic sulfonic thioanhydrides and exchange of the thiosulfonate products in polar solvents were examined.

No description available.

Thesis (M.S.)--Ohio University, August, 1993. / Title from PDF t.p.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1957. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 85-86).

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007. / Sotira Yiacoumi, Committee Member ; Patricia Sobecky, Committee Member ; Ching-Hua Huang, Committee Member ; Dr. Spyros Pavlostathis, Committee Chair ; Frank Loeffler, Committee Member.

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A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The sulfur removal methods from petroleum products have become an important research topic. Sulfur poisons the catalysts found in vehicles engines and it is also a major air pollutant (Nehlsen, 2005). Recent sulfur specifications require refineries to produce ultra-clean products (Ma et al., 2002). This work aims at exploring a batch adsorptive desulfurization technique using a polymer-supported imidation agent (PI) as an adsorbent. The test was carried out at atmospheric pressure and on two commercial diesel fuels with sulfur contents of 5200 (Case 1) and 670 (Case 2) mg/kg which resembles the feed and outlet streams from the hydrodesulfurization (HDS) reactor respectively. The adsorbent was synthesized according to the procedure described by Shiraishi et al. (2003), BET, FTIR, SEM equipped with EDS and TGA were used for charaterization of the adsorbent. The PI was successfully synthesized and its surface area was 0.5333 m2/g which was incredibly lower than that of the PI synthesized by Fadhel (2010). Hence carbon nanotubes (CNTs) were added to the solution with the aim of improving the sulfur removal efficiency of PI. The obtained results indicated that PI with CNTs yield better results than PI without CNTs. In overall, the lowest sulfur content of 3462 mg/kg (33% removal efficiency) and 26 mg/kg (96% removal efficiency) for Case 1 and Case 2 respectively were obtained. Furthermore, the adsorbents were most effective at lower mixing rates (150 – 400 rpm), longer contact time (30 – 40 hours), practically high adsorbent amount (1 g) and moderate lower temperatures (25 – 50 ºC). The Freundlich adsorption isotherm model was the best fit to the experimental data in both Case 1 and Case 2. The kinetic model that best fitted well the experimental data is the pseudo-second-order model for both Case 1 and Case 2. The kinetic rate constant for Case 2 (4.079 x 10-3g/mg.min) was greater than that for Case 1 (6.75 x 10-5g/mg.min) thus indicating that fuel with low sulfur content has a higher sorption uptake than fuel with high sulfur content. Based on the results obtained in this study, it is suggested that the adsorption of sulfur at high sulfur content fuel is not capable to be used as a complimentary method to the HDS process. On the other hand, at low sulfur content fuel, there is an opportunity for combining this method with the traditional HDS method to achieve ultra-clean fuel. / GR2016

An experimental system was built to test the effect of various process parameters on the performance of the Modified Dry Limestone Process (MDLP) for flue gas desulfurization. Two types of limestone, one calcitic and one dolomitic, were used. These materials were characterized by ICP analysis, X-ray diffraction, optical microscopy, SEM, and electron microprobe before and after reaction. Performance was judged on the basis of the formation of a friable gypsum reaction product and the maintenance of a pH of about 4.84 or higher in water through which the exit gases were bubbled. Two primary and one secondary parameter were identified as the most important for optimum performance of the MDLP. The two primary parameters were temperature and water content. A temperature of 68°-70°C promoted reaction, while no reaction occurred at 31°C. The solubility of SO₂ in water was the controlling factor for water content. A maximum ratio of about 3.4 g SO₂/100 g water at 69°C was necessary. The secondary parameter was the type of limestone used. A dolomitic limestone with a reasonable amount of Fe performed better than either marble or a calcitic limestone, both low in Fe. A reasonable amount of Fe and an extensive pore structure seem to be the most important factors in limestone SO₂ absorption performance. / Master of Science

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Thesis (M.S.)--Ohio University, August, 1997. / Title from PDF t.p.