Hydrogen sulphide – halogen complexes studied by matrix isolation vibrational spectroscopy

Electronic spectra and symmetry of metalloporphyrins in low-temperature rare gas and nitrogen matrices

Nucleic acid bases studied by matrix isolation vibrational spectroscopy: Uracil and deuterated uracils

Exploratory studies were made to determine the value of four potential catalysts in increasing the gas plating rate for nickel carbonyl. The catalysts studied were anhydrous ammonia, water vapor, oxygen, and hydrogen sulfide. No catalytic effect was observed for either ammonla alone or for water vapor alone. Oxygen was not tested alone. With hydrogen sulfide present in the 0.2 to 0.4% concentration range, significant improvement in plating rate was observed. The best results were obtained with mixtures of hydrogen sulfide and water vapor or mixtures of hydrogen sulfide and oxygen, using hydrogen sulfide concentrations of 0.2 to 0.8%, water vapor concentrations of 0.03 to 0.08%, and oxygen concentrations of 0.8 to 1.0%. The catalytic effect can also be used to reduce the temperature required s plating with nickel carbonyl. Using the hydrogen sulfide-oxygen mixture, nickel carbonyl gas plating was performed at room temperature on the following materials: iron, copper, aluminum, glass, paper, cardboard, cotton cloth, and cork. (auth)

Fluoroalcohols—XXI. Infrared, matrix infrared and Raman spectra of 1,1,1-trifluoro-2-propanol and its three deuterated analogues

Hydrogen sulfide reformation in the presence of methane

UV-light induced conformational changes of 2-pyridinecarboxylic acid in low-temperature argon matrices

The chemical reactions in the silent electric discharge were studied when hydrogen reacted on the following inorganic solid substances. (1) Potassium sulphite. Reaction products:—hydrogen sulphide potassium hydroxide. (2) Cadmium bromide. Reaction products:—metallic cadmium and hydrogen bromide. (3) Potassium perchlorate. Reaction products:—potassium chloride and water. (4) Mercuric cyanide. Reaction products:—metallic mercury and hydrogen cyanide. (5) Mercuric thiocyanate. Reaction products:—mercuric sulphide, metallic mercury, hydrogen cyanide, hydrogen sulphide, and thiocyanic acid. (6) Silver cyanide. Reaction products:—metallic silver and hydrogen cyanide. (7) Sodium thiocyanate. Reaction products:—sodium sulphide, hydrogen sulphide, and hydrogen cyanide. (8) Lead thiocyanate. Reaction products:—lead sulphide, hydrogen sulphide, and hydrogen cyanide. (9) Potassium cyanide. It was proved that potassium cyanide was hardly reduced under the conditions of this experiment. The writer wishes to express his appreciation of a grant from the Imperial Academy towards the expenses of this research.

Infrared spectra of Dewar 2-picoline in low-temperature argon matrices

Trihalogenomethane - base complexes studied by vibrational spectroscopy in low-temperature matrices

Experts have long projected that in the future solid oxide fuel cells (SOFCs) could provide a viable path for the replacement of existing power sources and the production of clean, secure, and sustainable energy. Today, not only have SOFCs matured as a technology with a proven ability to provide high density, high efficiency power with long term stability at low cost and environmental impact, but with the theoretical capacity to utilize a variety of naturally sourced fuels. This theoretical capacity makes their potential use attractive in many additional applications and positions SOFCs to be the technology which can bridge the gap between current hydrocarbon fueled technologies and future hydrocarbon fueled electric technologies. That said, there remains many technical hurdles associated with the incorporation of naturally sourced fuels, to include thermal stress cracking and catalyst coarsening, delamination, and poisoning. Catalyst poisoning, specifically arising from sulfur impurities in naturally sourced fuels, remains one of the largest SOFC technical challenges, since their presence, even at low concentrations, have now shown permanent performance degradation. As the U.S. Army begins to investigate SOFCs to enable additional capabilities like silent watch, advanced radios, and exportable power in their fleet, catalyst poisoning from sulfur impurities presents a concerning technology gap which must be addressed, as the entire fleet operates on JP-8 kerosene-based fuel, which by specification can contain up to 3000 ppm of sulfur, via AR-70 single fuel policy.As SOFC technologies migrate to lower temperature operation to resolve physical degradation issues, the development catalysts materials with greater sulfur tolerance are being explored to resolve issues of chemical degradation related to sulfur poisoning. In this study, a previously reported, high temperature, sulfur tolerant SOFC catalyst, La0.7Sr0.3VO3.86-⸹ (LSV), was further experimentally investigated via Optical Microscopy, X-ray Diffraction, Scanning Electron Microscopy and Energy Dispersive Spectroscopy for its sulfur tolerance at currently targeted SOFC intermediate operating temperatures (400-600°C) in wide range of hydrogen sulfide (30ppm, 300ppm and 10vol%) balance hydrogen gas environments for up to 100 hours. When compared against the industry standard Ni-YSZ anode, LSV was observed to have significantly lower (287x) sulfur adsorption rates, with the lowest rates observed between 600-700°C. This behavior is attributed the cubic structure the material presents in this temperature range. Higher adsorption rates were observed in the monoclinic/tetragonal structure the material presents at temperatures between 400-500°C. This study was further supplemented by a theoretical investigation of hydrogen sulfide adsorption on low index LSV surfaces via periodic Density Functional Theory. When compared against Ni-YSZ, which is known to accumulate sulfur from hydrogen sulfide via two-step dissociative adsorption, LSV was observed to accumulate sulfur through weak chemisorption (0.43 eV max) of undissociated molecular hydrogen sulfide only. The weak chemisorption behavior is attributed to structural surface changes due to oxygen vacancies near strontium defects, wherein the strongest adsorption energies were observed, and in direct contrast to similar calculations of hydrogen sulfide adsorption with low index surfaces of LVO3, wherein no adsorption was observed.Since it is likely SOFCs will operate on hydrocarbon fuels, as well as compressed hydrogen gas in the future, this study is also currently experimentally investigating sulfur accumulation under the same operating conditions above with hydrogen sulfide mixtures in methane gas. Methane is a small hydrocarbon chain, which will help minimize the accumulation of carbon deposition. Initial comparisons of sulfur adsorption between hydrogen and methane gas mixtures, using low hydrogen sulfide concentrations, show they are statistically similar, although methane gas exposure was observed to result in the formation of two activation energies, which was not observed with hydrogen mixture previously. The methane gas was also observed to promote LSV to take the monoclinic/tetragonal structure at lower operating temperatures than hydrogen mixtures. This observation may lead to elevated sulfur adsorption rates at higher hydrogen sulfide concentrations. Finally, it was originally observed during experimental exposure experiments with hydrogen sulfide/hydrogen gas balance mixtures that higher concentrations of lattice oxygen, present at lower temperatures, had a positive correlation with sulfur accumulation in the LSV material. This study is therefore currently theoretically investigating the effect of lattice oxygen content on the LSVs structure via Density Functional Theory, which could lead to further derivation from optimal cubic configuration, which may lead to configurations which increase sulfur adsorption. Figure 1

Reevaluation of matrix-isolation infrared spectra of the isotopologues of trans-diazene and attempts to prepare cis-diazene by photoisomerization

Unusual behavior of the pyrimidine–2-hydroxypyrimidine heterodimer isolated in argon matrices

1. The dynamics of the changes of the properties of rubber during vulcanization by a mixture of sulfur dioxide and hydrogen sulfide, in distinction from conventional vulcanization by sulfur, is expressed by smooth curves. No vulcanization optimum is observed. 2. With multiple cycles of vulcanization, the increase of bound sulfur content above 3 per cent results in a decrease of tensile strength. 3. Changes of tensile strength of the vulcanizate dependent on changes of sulfur content are attributable to the influence of the density of the spatial network on the orientation processes during deformation.

The solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution has been determined at temperatures of 40°C and 100°C. Partial pressures of CO2 ranged from 0.7 to 5630 kPa, while partial pressures of H2S ranged from 0.7 to 3780 kPa. The present results extend the published data on this system which were limited to partial pressures below 200 kPa. The results have been compared with two methods of prediction based upon a thermodynamic model.

Photoisomerization of acetyl methyl iminoxy radical in low-temperature argon matrices studied by density functional theory