Partial Oxidation Of H2S Research Articles

Radiofrequency-driven selective oxidation of H2S on hierarchical metal-free catalyst containing defects

Hierarchical all carbon metal-free catalyst with controlled macroscopic shape based on the carbon nanotubes decorated carbon felt (CNT@CF) has been prepared. The catalyst was further treated under gaseous nitric acid to generate structural defects on its surface (o-CNT@o-CF). The as-synthesized catalyst was evaluated in the partial oxidation of H2S by oxygen into elemental sulfur in a fixed-bed reactor under a direct and non-contact inductive heating mode. The catalytic results indicate that the o-CNT@o-CF catalyst exhibits an extremely high desulfurization performance under inductive heating mode. The high desulfurization performance was attributed to the high effective heat management inside the catalyst through inductive heating along with a short diffusion length associated with the nanoscopic dimension of the carbon nanotubes. The catalyst also displays a high stability as a function of time on stream.

Numerical analysis of H2 formation during partial oxidation of H2S[sbnd]H2O upon activation of oxidizer by an electric discharge

The numerical analysis of H2 production during partial oxidation of H2SH2O in a plug-flow reactor at atmospheric pressure and a rather low temperature (T0 = 500 K) was conducted, when the oxidizer (oxygen or air) was preliminarily activated by an electrical discharge with different values of reduced electric field and input energy. It was shown that a significant hydrogen yield in flow reactor can be obtained only after ignition of the mixture. The ignition delay length depends on the reduced electric field E/N and input energy Es in the discharge and is minimal at E/N∼8–10 Td for the discharge in oxygen and at E/N∼4–10 and 120–150 Td in air discharge, when O2(a1Δg) mole fraction in the discharge products is maximal. If the H2SH2OO2(air) mixture ignites inside the flow reactor, the mole fraction of hydrogen and its relative yield do not depend on E/N. The relative hydrogen yield increases monotonically with an addition of water to H2S. It was found, that the approach based on the partial oxidation of the H2SH2O mixture upon activation of oxygen by an electric discharge can ensure very low energy cost for H2 production. The minimum specific energy requirement, obtained for the H2SO2 mixture, was found to be 0.83 eV/(molecule H2) and 0.18 eV/(molecule H2S) at atmospheric pressure and can be further decreased if the energy released during partial oxidation of H2S is spent on heating the reagents. The use of air as an oxidizer requires higher energy costs and seems to be less promising.

Numerical study of H2S-H2O-air mixture conversion to hydrogen via activation of air by an electric discharge

The numerical analysis of H2 production during partial oxidation of H2S–H2O–air in a plug-flow reactor at a rather low temperature (T 0=500 K) was conducted. For the reforming process promotion, the oxidizer (air) was activated by an electrical discharge with different values of reduced electric field E/N and input energy E s. It was shown that a significant hydrogen yield in a flow reactor can be obtained only after mixture ignition. The ignition delay length turned out to be minimal at E/N~4–10 and 120–150 Td, when O2(a1Δg) mole fraction in the discharge products is maximal. If the H2S–H2O–air mixture ignites inside the flow reactor, the H2 mole fraction and its relative yield do not depend on E/N. The relative hydrogen yield increases monotonically with an increase of H2O amount. The specific energy requirement for H2 production in considered process was evaluated.

Barite from the Saf’yanovka VMS deposit (Central Urals) and Semenov-1 and Semenov-3 hydrothermal sulfide fields (Mid-Atlantic Ridge): a comparative analysis of formation conditions

Different genetic types of barite from colloform and clastic pyrite-rich ores from the weakly metamorphic Saf’yanovka volcanogenic massive sulfide (VMS) deposit (Central Urals) were studied in comparison with barite from the Semenov-1 and Semenov-3 seafloor hydrothermal fields (mid-Atlantic Ridge). Hydrothermal barite generally occurs as radial aggregates of tabular crystals in contrast to compact aggregates of tabular crystals with stylolite boundaries of anadiagenetic barite from the Saf’yanovka clastic ores. The Sr content in barite shows no relationship with the genetic types. The δ34S values of hydrothermal barite from both ancient and modern colloform sulfides match those of Silurian–Devonian and contemporary seawater, respectively. The lower δ34S (avg +19.6 ‰) of hydrothermal barite from the Semenov-3 clastic sulfides indicates light sulfur contribution from oxidation of fluid H2S. The higher δ34S (avg +28.1 ‰) of anadiagenetic barite from the Saf’yanovka clastic ores reflects partial thermochemical reduction of seawater sulfate. Hydrothermal barite from the Saf’yanovka and Semenov-1 colloform ores formed from low- to moderate-T (172–194 °С and 83–233 °C, respectively) relatively low salinity (1.6–4.5 and 0.6–3.8 wt% NaCleq, respectively) fluids, which underwent phase separation. Hydrothermal barite from Semenov-3 clastic sulfides associated with chalcopyrite crystallized from higher-T (266–335 °С) higher-salinity (4.8–9.2 wt% NaCleq.) fluids. The high salinity may indicate a contribution from a magmatic fluid. Anadiagenetic barite from Saf’yanovka was formed from moderate-T (140–180 °С), low- to moderate-salinity (1.4–5.4 wt% NaCleq) pore fluids. Combining our new data with those for other seafloor hydrothermal barite occurrences, the following systematics can be defined. Barite associated with pyrite-rich sulfides forms at relatively low to moderate temperatures (<230 °C), barite associated with polymetallic-rich sulfides forms at moderately high temperatures (210–280 °C), and barite in assemblage with chalcopyrite records the highest temperatures (265–335 °C). The main source of sulfur for hydrothermal barite is seawater with a small contribution of isotopically light sulfur from partial oxidation of H2S. A contribution from isotopically heavy sulfur remaining after thermochemical or bacterial partial reduction of seawater sulfate appears to be common in diagenetic/anadiagenetic barite.

A process simulation study of hydrogen and sulfur production from hydrogen sulfide using the Fe–Cl hybrid process

Presently, most of the acid gas (H2S) streams from amine gas sweetening and refinery upgrading operations are treated using the modified Claus process. In this process, sulfur and low-quality steam are produced by partial oxidation of H2S. Despite the modified Claus process's success in accomplishing the above tasks, it still has some disadvantages. Additional tail gas treatment unit is needed to improve its efficiency. Also, a valuable commodity, hydrogen, is not recovered.In this work, a process simulation study on the Idemitsu Kosan Co. Fe–Cl hybrid process is carried out. The process is capable of producing sulfur and hydrogen from H2S gas streams. The process was modeled and validated using pilot-scale plant data before been scaled up using the typical acid gas composition profile of one of Abu Dhabi's sulfur recovery plants. The effects the absorber solution flow rate and concentration have on the process’ operability were investigated. Operating at high ferric ions concentration was found to be more beneficial compared to high solution flow rate operations. The ferrous ion constituent of the solution proves to be instrumental in the downstream electrolysis process. Cost estimates of the process indicate the suitability of the process to be implemented in Abu Dhabi gas plants to produce sulfur, and most importantly, hydrogen to be used as fuel or chemical feedstock.

Catalytic Oxidation and Stabilized Adsorption of Elemental Mercury from Coal-Derived Fuel Gas

The aim of this study is to develop an efficient process for the stabilized removal of elemental mercury (Hg0) from coal-derived fuel gas by the aid of the catalytic oxidation of Hg0 over activated carbon (AC). The experiments were performed in the temperature range of 120–240 °C with simulated coal-derived gases containing varying concentrations of CO, H2, CO2, H2O, and H2S. O2 was introduced to promote the oxidation reaction between H2S and Hg0 over the AC sorbent to form mercury sulfide (HgS). The results indicated that the Hg0 removal capacity of AC could be dramatically improved in the presence of both H2S and O2. The presence of O2 was indispensable for the efficient and stable removal of Hg0 from H2S-containing fuel gas. The high temperature and high content of reducing gases, such as CO and H2, may inhibit the oxidation reaction and decrease the Hg0 removal efficiency, whereas the high content of H2O can promote Hg0 removal. On the basis of thermodynamic analysis, as well as the temperature-programmed decomposition (TPD) and X-ray photoelectron spectroscopy (XPS) characterization of the sorbents, it is suggested that the partial oxidation of H2S with O2 to active sulfur may contribute to the stabilized removal of Hg0 by the reaction of active sulfur with Hg0 to form HgS.

Investigation of H2S oxidation by oxygen on oxide catalysts in sulfur condensation conditions

H2S oxidation with oxygen has been studied on three industrial oxide catalysts (Fe−Cr−Zn, Cu−Cr−Al, V−Ti−Al). Thermodynamically possible changes in the composition of the catalysts have been evaluated. Regularities determining deep or partial oxidation of H2S have been found. Deep oxidation is connected to the presence of active oxygen on the catalyst surface; its removal results in a decrease of activity and increase of the sulfur selectivity. Oscillations caused by periodic adsorption-desorption of sulfur on the catalyst surface have been observed on the most active V−Ti−Al catalysts in oxygen excess.

96/03656 Catalysts for hydrogenation of heavy oils and hydrogenation of heavy oils using them

Presently, most of the acid gas (H2S) streams from amine gas sweetening and refinery upgrading operations are treated using the modified Claus process. In this process, sulfur and low-quality steam are produced by partial oxidation of H2S. Despite the modified Claus process's success in accomplishing the above tasks, it still has some disadvantages. Additional tail gas treatment unit is needed to improve its efficiency. Also, a valuable commodity, hydrogen, is not recovered.In this work, a process simulation study on the Idemitsu Kosan Co. Fe–Cl hybrid process is carried out. The process is capable of producing sulfur and hydrogen from H2S gas streams. The process was modeled and validated using pilot-scale plant data before been scaled up using the typical acid gas composition profile of one of Abu Dhabi's sulfur recovery plants. The effects the absorber solution flow rate and concentration have on the process’ operability were investigated. Operating at high ferric ions concentration was found to be more beneficial compared to high solution flow rate operations. The ferrous ion constituent of the solution proves to be instrumental in the downstream electrolysis process. Cost estimates of the process indicate the suitability of the process to be implemented in Abu Dhabi gas plants to produce sulfur, and most importantly, hydrogen to be used as fuel or chemical feedstock.