Search Results (25)

SO₂ emissions are a major source of air pollution, and the catalytic reduction of SO₂ to elemental sulfur by CO represents a promising solution. This study investigates the effects of Fe doping and pre-sulfurization on the catalytic performance of LaCoO₃ perovskite catalysts. A series of Fe-doped LaCoO₃ perovskites were synthesized via the sol–gel method and evaluated for the catalytic reduction of SO₂ by CO. The results showed that LaCo_0.8Fe_0.2O₃ exhibited the highest catalytic performance, achieving 84.0% SO₂ conversion at 500 °C. The oxygen-free sulfurization (OFS) treatment compared with oxygen-assisted sulfurization (OAS) treatment significantly enhanced the activity, reaching a SO₂ conversion of 95.9% from 80.0% at 450 °C with the lower byproduct generation. Characterization analyses demonstrated that the OFS treatment facilitated the formation of active sulfur species and oxygen vacancies on the catalyst surface while also enhancing the adsorption capacity of the catalyst for the reactant gases. These factors were identified as key contributors to the improved catalytic performance, driven by the combination of redox and carbonyl sulfide (COS) intermediate mechanism. The findings suggest that the OFS treatment is an effective strategy to improve the catalytic reduction of SO₂ by CO, offering a more environmentally friendly solution for SO₂ emission control through resource utilization. Full article

Carbonyl sulfide (COS) is the most abundant and longest-lasting organic reduced sulfur compound in the atmosphere. Removing it is a critical and challenging aspect in desulfurization technology in order to comply with global restrictions on harmful emissions. Catalytic hydrolysis refers to the process whereby COS reacts with water under the influence of a catalyst to generate carbon dioxide and hydrogen sulfide. Due to its high conversion rate, minimal side reactions, no hydrogen consumption, and mature technology, it has emerged as the most crucial COS removal method at present. Since its inception in the 1940s, research on the catalytic hydrolysis of COS has witnessed encouraging progress over the past several decades. This review summarizes recent advancements in this field. In this review, the evaluation metrics, influencing factors, and reaction mechanism for the COS hydrolysis reaction are briefly introduced. The recent advancements in COS hydrolysis catalysts in recent years are emphasized. Additionally, the existing challenges and potential solutions in this field are also proposed. Finally, the future development directions for this research area are envisioned. The purpose of this review is to offer a reference for the subsequent design and research of high-activity and high-stability hydrolysis catalysts. Full article

In this work, a highly sensitive, selective, and industrially compatible gas sensor prototype is presented. The sensor utilizes three distributed-feedback quantum cascade lasers (DFB-QCLs), employing wavelength modulation spectroscopy (WMS) for the detection of hydrogen sulfide (H₂S), methane (CH₄), methyl mercaptan (CH₃SH), and carbonyl sulfide (COS) in the spectral regions of 8.0 µm, 7.5 µm, and 4.9 µm, respectively. In addition, field-programmable gate array (FPGA) hardware is used for real-time signal generation, laser driving, signal processing, and handling industrial communication protocols. To comply with on-site safety standards, the QCL sensor prototype is housed in an industrial-grade enclosure and equipped with the necessary safety features to ensure certified operation under ATEX/IECEx regulations for hazardous and explosive environments. The system integrates an automated gas sampling and conditioning module, alongside a purge and pressurization system, with intrinsic safety electronic components, thereby enabling reliable explosion prevention and malfunction protection. Detection limits of approximately 0.3 ppmv for H₂S, 60 ppbv for CH₃SH, and 5 ppbv for COS are demonstrated. Noise-equivalent absorption sensitivity (NEAS) levels for H₂S, CH₃SH, and COS were determined to be 5.93 × 10⁻⁹, 4.65 × 10⁻⁹, and 5.24 × 10⁻¹⁰ cm⁻¹ Hz^−1/2. The suitability of the sensor prototype for simultaneous sulfur species monitoring is demonstrated in process streams of a hydrodesulphurization (HDS) and fluid catalytic cracking (FCC) unit at the project’s industrial partner, OMV AG. Full article

Carbonyl sulfide (COS), an organosulfur compound commonly present in industrial gases, poses significant challenges for environmental protection and industrial processes due to its toxicity. This paper reviews recent advancements in the development of catalysts for COS hydrolysis, emphasizing the effects of various supports and active components on catalyst performance, as well as the mechanisms underlying the hydrolysis reaction. Traditional supports like γ-Al₂O₃ demonstrate high activity for COS hydrolysis but are susceptible to deactivation. In contrast, novel supports such as activated carbon, TiO₂, and ZrO₂ have garnered attention for their unique structures and properties. The incorporation of active components, including alkali metals, alkaline earth metals, transition metals, and rare earth metals, significantly enhances the hydrolysis efficiency and resistance to deactivation of the catalysts. Additionally, this paper outlines three primary mechanisms for COS hydrolysis: the alkali-catalyzed mechanism, the Langmuir–Hinshelwood model, and the Eley–Rideal model mechanism, as well as the thiocarbonate intermediate mechanism, which collectively elucidate the conversion of COS into the H₂S and CO₂ catalyzed by these systems. Future research efforts will concentrate on developing high-activity, high-stability, and cost-effective COS hydrolysis catalysts, along with a more in-depth exploration of the reaction mechanisms to facilitate the efficient removal of COS from industrial emissions. Full article

The gas phase reaction of fluorine atoms with carbonyl sulfide, F + OCS → SF + CO (1), has been investigated over a wide temperature range, T = 220–960 K, in a discharge-flow system combined with mass spectrometry for the analysis of the reactive mixture. The reaction rate coefficient was determined as a function of temperature using both absolute (under pseudo-first-order conditions using an excess of F atoms) and relative rate methods: k₁ = (8.95 ± 0.52) × 10⁻¹¹ exp((102 ± 20)/T) cm³ molecule⁻¹ s⁻¹ (with an estimated total uncertainty of 15% independent of temperature). The SF radical was observed as the main primary reaction product. The experimental results are supported by theoretical calculations, which evidence that the reaction is exothermic with a weak negative temperature dependence. Full article

During the process of liquefied petroleum gas (LPG) exploitation, various sulfide-containing gases are produced, which significantly bring about corrosion attacks to copper equipment and facilities. Investigations on the effects of sulfides, hydrogen sulfide (H₂S), carbonyl sulfide (COS), and ethanethiol (C₂H₆S) on copper corrosion and synergistic mechanisms are of great significance for LPG production. This paper studied the synergistic corrosion effects of mixed sulfide-containing gases in LPG on copper plates, including the influence of H₂S + COS, H₂S + C₂H₆S, as well as H₂S + COS + C₂H₆S. The results showed that there exists an apparent synergistic effect between different sulfide-containing gases, which decreased the critical point of corrosion and enhanced the severity of copper corrosion. SEM observation on corrosion products with the addition of different sulfide-containing gases demonstrated that the microstructures of corrosion products are significantly different, which reveals different corrosion mechanisms. By characterizing the corrosion products on copper surfaces, corresponding corrosion mechanisms were proposed. Individual H₂S reacts with copper directly as chemical corrosion. The presence of water leads to the dissolution of H₂S into water film at the copper surface and results in electrochemical corrosion in nature. COS tends to decompose into acidic gas H₂S and CO₂, which accelerates the electrochemical corrosion at the copper surface. C₂H₆S can react with copper directly as chemical corrosion. A mixture of different sulfur-containing gases enhanced the corrosion attack by synergistic effect. Full article

China possesses a substantial capacity for coke production, resulting in the annual generation of over 100 billion standard cubic meters of the by-product coke oven gas. The comprehensive utilization of this gas has emerged as a matter of significant concern within the coking industry. The removal of carbonyl sulfide (COS) from coke oven gas is crucial for enhancing gas quality, mitigating equipment corrosion, minimizing environmental pollution, elevating the quality of recovered products, and fostering the production of high-quality steel. A novel Ca-Ba-γ-Al₂O₃ catalyst has been devised, employing γ-Al₂O₃ as the catalyst matrix and integrating calcium hydroxide (Ca(OH)₂) alongside barium hydroxide octahydrate (Ba(OH)₂·8H₂O) as the alkaline activating components. The impact of various factors, including reaction temperature, humidity, and the number of activating components loaded, on the hydrolysis efficiency of COS has been meticulously investigated. Furthermore, the catalytic reaction mechanism has been elucidated utilizing advanced characterization techniques such as X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis. The outcomes of this research reveal that, under optimal conditions of a reaction temperature of 55 °C and a humidity of 56%, the Ca-Ba-γ-Al₂O₃ catalyst achieves a remarkable COS hydrolysis efficiency of 95.22%. Full article

Over the past six decades, carbonyl sulfide (COS) in terrestrial ecosystems has been extensively studied, with research focusing on exploring its ecological and environmental effects, estimating source–sink volume, and identifying influencing factors. The global terrestrial COS sink has been estimated to be about 1.194–1.721 Tg a⁻¹, with the terrestrial sink induced by plants and soils 0.50–1.20 Tg a⁻¹, accounting for 41%–69% of the total. Hence, the role of plants and soils as COS sinks has been extensively explored. Now we know that factors such as the activity of carbonic anhydrase (CA), leaf structural traits, soil microbial activity, and environmental factors play significant roles in the COS budget. Developments in observational techniques have also made important contributions to the COS budget. This paper provides an overview of the research progress made on COS based on a comprehensive review of the literature. Then, it highlights the current research hotspots and issues requiring further exploration. For instance, it has been demonstrated that there are still significant uncertainties in the estimation of COS sources and sinks, emphasizing the need for further exploration of COS measuring techniques. This review aims to provide comprehensive guidance for COS research in terrestrial ecosystems. Full article

Herein, we present the first examples of amino acid decarboxylation via photochemically activated carbonyl sulfide (COS) elimination of the corresponding thioacids. This method offers a mild approach for the decarboxylation of amino acids, furnishing N-alkyl amino derivatives. The methodology was compatible with amino acids displaying both polar and hydrophobic sidechains and was tolerant towards widely used amino acid-protecting groups. The compatibility of the reaction with continuous-flow conditions demonstrates the scalability of the process. Full article

Sulfur-resistant Mo-based catalysts have become promising for the one-step synthesis of methanethiol (CH₃SH) from CO/H₂/H₂S, but the low reactant conversion and poor product selectivity have constrained its development. Herein, we synthesized K-MoS₂/Al₂O₃ and K-Mo₂C/Al₂O₃ catalysts via the sulfurization and carbonization of K-Mo-based catalysts in the oxidized state, respectively. During the synthesis of CH₃SH, both K-Mo₂C/Al₂O₃ and K-MoS₂/Al₂O₃ showed excellent catalytic performance, and the activity of the former is superior to that of the latter. The effect of different treatments on the catalytic performance of Mo-based catalysts was investigated by XRD, BET, Raman spectroscopy, H₂-TPR, and reactants-TPD characterization. The results showed that the sulfide-treated sample showed stronger metal-support interactions and contributed to the formation of K₂S, which exposed more active sites and stabilized the formation of C-S bonds. Carbonized samples enhanced the activation of H₂, which promoted the hydrogenation of the intermediate species of carbonyl sulfide (COS) and thus improved the selectivity of CH₃SH. Full article

The release behavior of sulfur and chlorine compounds into the gas phase of walnut shell particles (WNS) is studied with an entrained flow reactor. Experiments are carried out in nitrogen (N₂), carbon dioxide (CO₂) atmosphere and under air and oxy-fuel conditions at different temperatures (T = 1000–1300 °C) and stoichiometries ($\lambda$ = 0.8–1.1). A total of 98.7% of fuel-bound sulfur volatilizes as sulfur dioxide (SO₂), carbonyl sulfide (COS) and hydrogen sulfide (H₂S) in the gas phase in N₂ atmosphere at 1000 °C. As hydrogen chloride (HCl), 37.0% of the chlorine is released at this temperature. In CO₂ atmosphere, a similar total release of sulfur and chlorine is observed (1000 °C). With each temperature increment, the release of SO₂, H₂S and HCl in the gas phase decreases (N₂ and CO₂ atmosphere). SO₂ forms the major sulfur component in both atmospheres. In CO₂ atmosphere, higher concentrations of COS were detected than in N₂ atmosphere. Air and oxy-fuel combustion conditions show significantly lower SO₂, COS and HCl concentrations as in N₂ and CO₂ atmosphere. No H₂S is detected in the gas phase during any of the combustion trials. Full article

Bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES) is a selective inhibitor of glutaminase-1 (GLS1), consequently inhibiting glutaminolysis. BPTES is known for its potent antitumor activity and plays a significant role in senescent cell removal. In this study, we synthesized [¹¹C-carbonyl]BPTES ([¹¹C]BPTES) as a positron emission tomography (PET) probe for the first time and assessed its biodistribution in mice using PET. [¹¹C]BPTES was synthesized by the reaction of an amine precursor () with [¹¹C-carbonyl]phenylacetyl acid anhydride ([¹¹C]2), which was prepared from [¹¹C]CO₂ and benzyl magnesium chloride, followed by in situ treatment with isobutyl chloroformate. The decay-corrected isolated radiochemical yield of [¹¹C]BPTES was 9.5% (based on [¹¹C]CO₂) during a synthesis time of 40 min. A PET study with [¹¹C]BPTES showed high uptake levels of radioactivity in the liver, kidney, and small intestine of mice. Full article

Atmospheric carbonyl sulfide (COS) was monitored at the GIF site (France) from August 2014 to November 2021. A significant decreasing trend in the seasonal cycle amplitude (SCA) of the COS was observed for the first time in the Northern Hemisphere (−27 ppt over 6 years). The lowest SCA was recorded in 2021 (80 ppt vs. 107 ppt in 2015). The trend in the SCA results revealed a steeper decline in the spring maximum than in that of the autumn minimum (−49 ppt vs. −10 ppt over 6 years, respectively). These negative trends were qualitatively consistent with those in the tropospheric COS put forward by the NDACC network of ground-based FTIR instruments, which were attributed to a slowing in the rate of COS anthropogenic emissions. Simulations using the ORCHIDEE land-surface model showed that a decrease in COS lowers the uptake of this gas by plants. Our observations suggest the existence of a causal relationship between the decline in the SCA and that in the tropospheric COS, implying that the temporal variations in the COS SCA over Western Europe are essentially driven by plant uptake. However, the transport by the LMDz 3-D model of surface fluxes for each component of the COS budget failed to reproduce this feature at GIF, pointing to a likely misrepresentation of the marine and anthropogenic fluxes in the footprint of this station. Full article

As a trace gas involved in hydration during plant photosynthesis, carbonyl sulfide (COS) and its leaf relative uptake rate (LRU) is used to reduce the uncertainties in simulations of gross primary productivity (GPP). In this study, 101 independent observations were collected from 22 studies. We extracted the LRU, stomatal conductance (g_s), canopy COS and carbon dioxide (CO₂) fluxes, and relevant environmental conditions (i.e., light, temperature, and humidity), as well as the atmospheric COS and CO₂ concentrations (${\mathrm{C}}_{\mathrm{a},\mathrm{COS}}$ and ${\mathrm{C}}_{\mathrm{a},\mathrm{CO}2}$). Although no evidence was found showing that g_s regulates LRU, they responded in opposite ways to diurnal variations of environmental conditions in both mixed forests (LRU: Hedges’d = −0.901, LnRR = −0.189; g_s: Hedges’d = 0.785, LnRR = 0.739) and croplands dominated by C3 plants (Hedges’d = −0.491, LnRR = −0.371; g_s: Hedges’d = 1.066, LnRR = 0.322). In this process, the stomata play an important role in COS assimilation (R² = 0.340, p = 0.020) and further influence the interrelationship of COS and CO₂ fluxes (R² = 0.650, p = 0.000). Slight increases in light intensity (R² = 1, p = 0.002) and atmospheric drought (R² = 0.885, p = 0.005) also decreased the LRU. The LRU saturation points of C_a,COS and C_a,CO2 were observed when ΔC_a,COS ≈ 13 ppt (R² = 0.580, p = 0.050) or ΔC_a,CO2 ≈ −18 ppm (R² = 0.970, p = 0.003). This study concluded that during plant photosynthesis and COS assimilation, light and water conditions co-regulated the stomata and LRU. Full article

Sulphide gas is an impurity that affects the quality of natural gas, which needs reasonable storage and transportation. In this work, we investigated the adsorption structure and electronic behavior of hydrogen sulfide (H₂S), carbonyl sulfur (COS), and methyl mercaptan (CH₃SH) on sulphide gas molecules on pure and vacant α-Fe₂O₃(001) surfaces by density functional theory with geometrical relaxations. The results show that H₂S and CH₃SH are mainly adsorbed in the form of molecules on the pure Fe₂O₃(001) surface. On the vacant α-Fe₂O₃(001) surface, they can be adsorbed on Fe atoms in molecular form and by dissociation. The absolute value of the adsorption energy of H₂S and CH₃SH on the vacancy defect α-Fe₂O₃ surface is larger, and the density of states show that the electron orbital hybridization is more significant, and the adsorption is stronger. The charge differential density and Mulliken charge population analysis show that the charge is rearranged and chemical bonds are formed. The affinity of H₂S to the vacancy α-Fe₂O₃(001) surface is slightly higher than that of CH₃SH, while COS molecules basically do not adsorb on the α-Fe₂O₃(001) surface, which may be related to the stable chemical properties of the molecules themselves. Full article