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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.

As natural gas production has shifted further from deep prolific gas reservoirs to shale gas, several questions are being addressed regarding fracturing technologies and the fate of chemical additives. A less investigated issue is the unexpected increase in produced hydrogen sulfide (H2S) from hot shale gas reservoirs. Understanding the source of H2S in shale reservoirs and managing low-levels of recovered elemental sulfur affects plans for future treatment, corrosion mitigation, and fracture fluid formulations. In this work we demonstrate that some typical ingredients of hydraulic fracturing fluids are not as kinetically stable as one might expect. Surfactants and biocides such as sodium dodecyl sulfate and glutaraldehyde are shown to undergo hydrolysis and thermochemical sulfate reduction reactions under moderate reservoir conditions, with H2S as the final product accompanied with long chain alcohols and hydrogen sulfate as long-lived intermediate species. This finding suggests that fracture fluid addit...

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.

The need for fundamental data describing the dissolution of hydrogen sulfide, H2S, in Claus recovered liquid sulfur prompted an examination of equilibrium H2S solubility at typical industrial condensation temperatures and partial pressures. An FT/IR absorption technique has been described and new H2S solubility measurements have been reported for partial H2S pressures from 0.4 to 56 kPa and temperatures from 120 to 155 °C. The measurements were combined with previously reported values for atmospheric pressures of H2S and used to calibrate a semi-empirical equation for the Henry's law solubility in liquid sulfur as a function of temperature. Estimations were compared to Claus plant field data and appear to underestimate the H2S solubility for the first and second catalyst condenser stages. This underestimation was attributed to rapid condensation resulting in super-saturation of the recovered sulfur liquid, or an inaccurate measurement of the condensation temperatures.

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.

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.

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.