Kevin L. Lesage

The chemistry of organosulphur compound types occurring in heavy oils: 4. the high-temperature reaction of thiophene and tetrahydrothiophene with aqueous solutions of aluminium and first-row transition-metal cations

In the reactions of thiophene and tetrahydrothiophene with aqueous solutions of first-row transition-metal and aluminium cations at 240 °C and 3.4 MPa all the metal species accelerated the decomposition of the thiophenes in relation to equivalent reactions with pure water. Al3+, Sc3+, VO2+, Cr3+, Ni2+ and Cu2+ were most reactive towards thiophene and Al3+, VO2+, Cr3+ and Cu2+ were most reactive towards tetrahydrothiophene. Principal products were H2S and complex mixtures of organic products. The presence of CO2 and oxygen-containing organic products revealed that water was involved in direct chemical reaction with the substrates. It is likely that these model reactions parallel more complex processes that occur during the steam-stimulated recovery of oil-sand bitumen and other high-sulphur oils.

Chemistry of organosulphur compound types occurring in heavy oil sands: 5. Reaction of thiophene and tetrahydrothiophene with aqueous Group VIIIB metal species at high temperature

Abstract As part of a study of organosulphur compounds in heavy oil sands, the interaction of thiophene (1) and tetrahydrothiophene (10) with aqueous solutions of Group VIIIB metal species at 200–240 °C has been investigated. Thiophene was the more reactive and the greatest degree of reaction was observed with the second- and third-row members of the Group VIIIB metals. Aqueous Pt(IV) gave most reaction for both substances. Desulphurization of the sulphur compounds was significant, although conversion to more complex organic substances, including dithienyls and benzothiophene, account for > 50 wt % of the total reaction for most metal species. The presence of CO2 in the products showed that water was involved in the reaction. Reactions with thiophene produced only minor amounts of C1C4 hydrocarbons, but significant quantities were obtained from reactions with tetrahydrothiophene.

Selective Adsorption of Thiols Using Gold Nanoparticles Supported on Metal Oxides

Selective capture of thiols from a synthetic hydrogen sulfide containing mixture using supported nanogold materials has been explored for the potential removal of thiols from sour gas production fluids. In this research, TiO2-, Al2O3-, SiO2-, and ZnO-supported gold nanoparticles have been studied for their usage as regeneratable adsorbents to capture CH3SH, C2H5SH, and i-C3H7SH. Au/TiO2 and Au/Al2O3 showed promising properties for removing the thiols efficiently from a gas-phase mixture; however, Au/Al2O3 did catalyze some undesirable side reactions, e.g., carbonyl sulfide formation. It was found that a mild temperature of T = 200 °C was sufficient for regeneration of either Au/TiO2 or Au/Al2O3 adsorbent. The metal oxide mesopores played an important role for accommodating gold particles and chemisorption of the thiols, where smaller pore sizes were found to inhibit the agglomeration/growth of gold particles. The nature of thiol adsorption and the impact of multiple adsorption-desorption cycles on the adsorbents have been studied using electron microscopy, XPS, XRD, GC, and physi/chemiadsorption analyses.

Analytical procedure for the determination of trace carbon impurity in elemental sulfur

An analytical procedure has been developed for determining trace levels of carbon in elemental sulfur based on the standard combustion technique and incorporating gas chromatographic (GC) analysis of the products. Laboratory testing has shown a relative error of 5 ppmw or 5%, whichever is greater, in the results of the analysis for carbon contents of 50 ppmw and above and detection threshold of 15 ppmw carbon, along with good reproducibility.

Studies on the Chemistry OF H2S and H2Sx in Liquid Sulfur

Abstract The kinetics of removal of H2S and H2Sx from liquid sulfur using air sparging and amine catalysts is discussed. Removal by air is suggested to occur by reaction of O2 with H2S and H2Sx both in solution and in the headspace above the liquid sulfur forming S8 and SO2. The SO2 so formed likely reacts with H2S/H2Sx. Treatment of liquid sulfur containing H2S/H2Sx with amines results in sulfur containing no polymeric sulfur. This is believed to occur by proton abstraction from H2Sx and decomposition of the resulting HSx − anion to S8 and eventual formation of H2S.

The rheology of liquid elemental sulfur across the λ-transition

Seventy million tons of sulfur were produced worldwide in 2016. Much of the transportation and handling of molten sulfur require sulfur pumps which are challenging to operate due to the anomalous behavior of sulfurs liquid viscosity at temperatures near its λ-transition region. Sulfurs viscosity decreases from ca. 30 × 10−2 to ca. 7 × 10−2 Pa s when heating from the melt at T = 115 °C and then increases dramatically at T > 160 °C to a maximum of 93 000 × 10−2 Pa s at T = 187 °C. While the temperature of this viscosity transition is well known, no shear related information can be found in the literature and previous low-shear data do not address thermal hysteresis behavior (viscosity differences for cooling or heating) when sulfur is heated beyond 210 °C. This work is focused on reinvestigating the low-shear viscosity of molten sulfur which was initially studied by Bacon and Fanelli [J. Am. Chem. Soc. 65, 639–648 (1943)] and the effects of high-shear. The rheology of molten sulfur was studied using an An...

Organosulfur adsorbents by self-assembly of titania based ternary metal oxide nanofibers

By doping with secondary and tertiary species, the electron configuration of titanium oxide can be tuned for the selective adsorption of natural gas contaminants such as thiols. In this study, we attempted to co-incorporate copper group metals/oxides and lanthanum oxide within titania nanofibers via linear poly-condensations of multiple metal acetate complexes. In all cases, a sol–gel synthesis in heptane allowed the nanofibers to randomly pack, forming 3 dimensional network bundles. The resulting nanostructures were characterized using electron microscopy, mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, N2 physisorption and Raman spectroscopy. Multicomponent breakthrough studies with three thiols, H2S, CO2 and CH4 show that doping a TiO2 matrix with copper group metals/oxides and La2O3 increased the thermal stability of anatase crystallites and nanostructures. We note that Au and Ag2O accumulated on the surfaces of the doped materials, where the La2O3 doping contributed more to the materials thermal stability. The Cu and La doped material was found to be the best adsorbent for thiols with remarkably high selectivity, demonstrating potential applications in industrial gas treatment. In addition, xerogel adsorbents through the random packing of linear structures provide the advantage of a macro-porous bulk material, which is less susceptible to fouling.