Selective H2S Research Articles

MOF-SMO hybrids as a H2S sensor with superior sensitivity and selectivity

The detection of H2S is essential due to its dangerous toxicity and extensive existence in the oil and gas industries. Zeolitic imidazolate framework-8 (ZIF-8) particle-loaded ZnO nanorod hybrid is designed and fabricated as a gas sensor, which exhibits a superior sensitivity and selectivity for H2S at room temperature. ZIF-8 plays a key role in improving the sensitivity and selectivity of ZIF-8/ZnO nanorod sensor. The loading of porous ZIF-8 particles on the ZnO surfaces provides larger surface areas and more oxygen vacancies and reacts with H2S. Thus, ZIF-8/ZnO nanorod sensor has a better H2S adsorption function and transduction function compared to raw ZnO nanorod sensor. Remarkably, the response of ZIF-8/ZnO nanorod sensor to 10 ppm H2S is 52.1% even at 25 °C, which is 15 times higher than that of raw ZnO nanorod sensor. ZIF-8/ZnO nanorod sensor is able to detect H2S at a level down to 50 ppb. Moreover, it shows an excellent selective sensitivity for H2S over other reducing gases. High-performance H2S sensor is realized by the integration of metal-organic frameworks (MOFs) with semiconductor metal oxides (SMOs).

Adsorption of hydrogen sulfide, carbon dioxide, methane, and their mixtures on activated carbon

H2S and CO2 are acid contaminants of natural gas and biogas, which removal have been studied using adsorption data for monocomponent and binary mixtures. However, equilibrium adsorption data for H2S + CO2 + CH4 mixture has not been investigated yet. In this work, H2S and CO2 partition coefficients (K) and activated carbon (AC) selectivity (S) for H2S + CO2 + CH4 mixture separation at high-pressure and different temperatures were determined. To reach this goal, monocomponent isotherms for H2S, CO2 and CH4 on Brazilian babassu coconut hush AC were experimentally determined at different temperatures and pressures. Then, obtained data were correlated by Langmuir and Tóth models, and multicomponent adsorption was predicted using Extended Langmuir, Extended Tóth and Ideal Adsorption Solution Theory (IAST) methods. Results indicate AC captures approximately 26 wt% of H2S or CO2. K values for CO2 and H2S reached more than 3 and 26, respectively, depending on the predictive model utilized and were higher for diluted mixtures (high CH4 content in gas phase). S values for CO2 and H2S can reach values greater than 25 for Tóth + IAST. Furthermore, selectivity toward H2S is approximately 5.6 times greater than CO2. The effect of temperature on multicomponent results indicate K and S values decrease as temperature increases. Therefore, results obtained herein show that is possible to separate H2S and CO2 from mixture containing CH4 using this AC as adsorbent and better separation performance was observed for low H2S and CO2 concentrations and lower temperatures.

BODIPY-based naked-eye fluorescent on-off probe with high selectivity for H2S based on thiolysis of dinitrophenyl ether

1-(2-Hydroxyphenyl)ethanone as a starting material, BODIPY 3 bearing 2,4-dinitrophenyl (DNP) group was prepared in total 7% yield. Probe 3 was strongly fluorescent. Sulfhydryl-specific cleavage reaction released the hydroxyl group. Due to the electron transfer of the hydroxyl group in 2 to the BODIPY core, dye 2 was weakly fluorescent. Naked-eye and fluorescent turn-off probe 3 was highly selective and sensitive to H2S, and could be used to detect HS− in HCT-116 and CT-26 cells, indicating its potential application for studying the effect of HS− in biological system.

Highly Sensitive and Selective H2S Chemical Sensor Based on ZnO Nanomaterial

ZnO is worth evaluating for chemical sensing due to its outstanding physical and chemical properties. We report the fabrication and study of the gas sensing properties of ZnO nanomaterial for the detection of hydrogen sulfide (H2S). This prepared material exhibited a 7400 gas sensing response when exposed to 30 ppm of H2S in air. In addition, the structure showed a high selectivity towards H2S against other reducing gases. The high sensing performance of the structure was attributed to its nanoscale size, morphology and the disparity in the sensing mechanism between the H2S and other reducing gases. We suggest that the work reported here including the simplicity of device fabrication is a significant step toward the application of ZnO nanomaterials in chemical gas sensing systems for the real-time detection of H2S.

Study of Various Aqueous and Non-Aqueous Amine Blends for Hydrogen Sulfide Removal from Natural Gas

Various novel amine solutions both in aqueous and non-aqueous [monoethylene glycol (MEG)/triethylene glycol(TEG)] forms have been studied for hydrogen sulfide (H2S) absorption. The study was conducted in a custom build experimental setup at temperatures relevant to subsea operation conditions and atmospheric pressure. Liquid phase absorbed H2S, and amine concentrations were measured analytically to calculate H2S loading (mole of H2S/mole of amine). Maximum achieved H2S loadings as the function of pKa, gas partial pressure, temperature and amine concentration are presented. Effects of solvent type on absorbed H2S have also been discussed. Several new solvents showed higher H2S loading as compared to aqueous N-Methyldiethanolamine (MDEA) solution which is the current industrial benchmark compound for selective H2S removal in natural gas sweetening process.

H2S separation from biogas by adsorption on functionalized MIL-47-X (X = −OH and − OCH3): A simulation study

Monte Carlo molecular simulations in grand canonical ensemble were performed to study the H2S, CO2 and CH4 adsorption and separation on the MIL-47 and the functionalized MIL-47-X (X = -OH and -OCH3). The preferred situation for the adsorption of gas molecules on the studied MOFs was also investigated. The calculated adsorption isotherms of CO2 on the MIL-47 agreed well with the experimental uptakes. Furthermore, the simulated adsorption selectivities of three MOFs for the CO2/CH4, H2S/CH4 and H2S/CO2 mixtures were in the order H2S/CH4 > H2S/CO2 > CO2/CH4. These MOFs had higher selectivity for H2S over CH4 indicating that they can be good adsorbents for the H2S separation. The probability distribution of the adsorbed molecules showed that the guest molecules were more localized near the metal centers and functional groups.

Co3O4/carbon hollow nanospheres for resistivemonitoring of gaseous hydrogen sulfide and for nonenzymatic amperometricsensing of dissolved hydrogen peroxide.

Co3O4/carbon hybrid hollow nanospheres (hs-Co3O4/C) with an empty cavity and a thin shell, were synthesized starting from the pectin and cobalt acetate via cross-linking deposition at room temperature and post-calcination. The hierarchical structure is constructed from the interconnected nanoparticles in the residual carbon matrix, and the carbon content can be adjusted by changing the calcination temperature. The gas sensor based on hs-Co3O4/C calcined at 300°C in air shows high response towards 50ppm of H2S (S = 95.5) and good selectivity at a low working temperature (92°C). The detection limit is as low as 0.1ppm. The non-enzymatic glassy carbon electrode basedsensor constructed from the same material exhibits excellent electrocatalytic activity for H2O2 with the sensitivity of 405.8μA∙mM∙cm-2 at 0.3V (vs. SCE) in alkaline solution. The chronoamperometric response time is <3s and the detection limit (at S/N= 3) is 0.30μM. The good sensing performances are attributed to the synergetic effect of unique hollow nanostructure and appropriate amount of carbon in the hybrid material. The porous nanostructure can increase the mass transfer efficiency, and the cross-linked nanoparticles with good crystallinity also improve the conductivity of materials. The presence of carbon enhances the charge transfer ability and increases the specific surface, thereby improving the sensor performance. Graphical abstract Schematic illustration of the formation of hollow Co3O4 nanospheres composited with pectin-derived carbon. The materialdisplays excellent selectivityforH2S gas and in non-enzymaticdetection of dissolved H2O2.

Gas Hydrate Formation Process for Simultaneously Capture of CO2 and H2S

Simultaneously capture of CO2 and H2S is vital for obtaining clean fuels from fossil fuels. This work proposes the hydrate formation process for simultaneously capture of CO2 and H2S from simulated syngas with new synergic additives. The synergic additives comprises acidic gas solvent (tetramethylene sulfone (TMS)) and traditional hydrate promoter (tetra-n-butyl ammonium bromide (TBAB)). The effect of the synergic additives was evaluated based on kinetic curves, separation efficiency and gas selectivity. The results show that, with the help of the synergic additives, both CO2 or H2S could be simultaneously captured from the simulated syngas by the hydrate formation process. Furthermore, the synergic additives could not remarkably accelerate the formation rate and improve the gas storage capacity for the simulated syngas hydrate, but also enhance the selectivity of CO2 or H2S in the hydrate process.

Highly sensitive and selective H2S gas sensors based on flower-like WO3/CuO composites operating at low/room temperature

The highly sensitive hydrogen sulfide (H2S) gas sensor was developed from a semiconductor composite structure composed of flower-like WO3 microspheres whose surface was modified with CuO nanoparticles. The composites were prepared by a simple two-step hydrothermal method. The morphology and structure of the samples were examined by XRD, SEM, TEM and BET. The sensing properties of the samples on H2S at different operating temperatures were examined, and the performance of WO3/CuO with different molar ratios was also investigated. Gas-sensing tests show that WO3/CuO composites exhibit high response, excellent selectivity and fast response to ppm-level H2S at low operating temperature of 80 °C. Beyond that, WO3/CuO composites with 7:1 M ratio was responsive to 5 ppm H2S at room temperature (28 °C), and its sensitivity could be reached 16. In addition, the gas sensing mechanism of flower-like WO3 microspheres modified with CuO nanoparticles was also thoroughly discussed. The enhanced sensing properties of composites were mainly attributed to the morphology structure and p-n heterojuction between flower-like WO3 and CuO nanoparticles.

Near room temperature operable H2S sensors based on In2O3 colloidal quantum dots

Indium oxide (In2O3) nanomaterials have been investigated extensively as promising candidates for gas sensor applications. Here, we fabricate near room temperature operable H2S-sensitive gas sensors based on In2O3 colloidal quantum dots (CQDs). Room-temperature film deposition of In2O3 CQDs followed by surface ligand exchange treatment through Cu inorganic salts was employed to construct the sensor devices. Combined with a moderate annealing treatment, the long-chain ligands surrounding the quantum dot surfaces were completely removed to enhance gas adsorption and carrier transport, simultaneously resulting in the formation of CuO that may act as a catalytic promoter or form p-n heterojunction for selective H2S detection. The sensors exhibited high response up to 90 toward 5 ppm of H2S with response/recovery time of 72 s/200 s respectively, suggestive of a performance improvement compared to the In2O3-based H2S sensors reported in existing literature.The power law analysis indicated that the main oxygen species adsorbed on the surfaces were O2− and O− with the proportion of approximate 1:1 at near room temperature. The gas-sensing mechanism was attributed to the decisive role of surface states in determining the electrical conduction of quantum dot gas sensors.

In Situ FMR Study of the Selective H2S-Oxidation Stability of ε-Fe2O3/SiO2 Catalysts

The stability of a catalyst for partial H2S oxidation has been studied by the ferromagnetic resonance (FMR) technique combined with transmission electron microscopy, X-ray diffraction, Mossbauer spectroscopy, and magnetostatic investigations. The e-Fe2O3 iron oxide nanoparticles supported on silica have been examined for their stability under the selective H2S oxidation conditions. The combination of the physicochemical methods has been used to study the state of reacted catalysts. The e-Fe2O3 phase has been found to remain stable under the selective H2S oxidation conditions at temperatures up to 300 °C. The active phase state during the catalytic reaction has been explored using in situ FMR experiments. It has been established that the e-Fe2O3 nanoparticles retain their structure and magnetic properties in the presence of H2S at high temperatures. During the in situ FMR experiments, the e-Fe2O3 sulfidation process has been studied.

Ultra-highly sensitive and selective H2S gas sensor based on CuO with sub-ppb detection limit

A gas sensor based on CuO has been fabricated to detect an ultra-trace H2S gas. The CuO samples were characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. The SEM results revealed that CuO exhibited a “grapes” structure made of nanoparticles. Gas-sensing properties of the CuO sensor were also studied. The sensor showed outstanding selectivity and high sensitivity to H2S gas, and achieved a ppb level detection limit. In addition, the temperature and humidity was also found to be significantly influential on the sensitivity of the sensor.

Investigation of selective desulfurization performance of sterically hindered amines

We investigated the H2S/CO2 gas mixture absorption rate and selectivity of 2-(tert-butylamino)ethanol (TBE) and 2-amino-2-methyl-1-propanol (AMP) using a static gas absorption method. The H2S and CO2 gas mixture was pumped into a reaction kettle filled with sterically hindered amines solubilized in water. The influence of time on the H2S absorption rate and selectivity of the sterically hindered amine solutions was investigated.

A mitochondria-targeted red-emitting probe for imaging hydrogen sulfide in living cells and zebrafish.

Hydrogen sulfide (H2S) is an important endogenous signaling molecule with multiple biological functions. Based on the thiolysis of NBD (7-nitro-1,2,3-benzoxadiazole) amine, herein we rationally design and synthesize a new fluorescent probe 1 for the detection of mitochondrial H2S in living cells. Probe 1 displays bright red-emitting fluorescence after H2S activation (φ, 0.77). 1 shows higher selectivity and sensitivity for H2S than the red-emitting probe Rho-NBD (ChemBioChem, 2016, 17, 962). Moreover, 1 is water-soluble, cell-membrane-permeable, of low cytotoxicity and mitochondria-targeting, and can be employed for monitoring mitochondrial H2S in living cells.

Rationally designed pure-inorganic upconversion nanoprobes for ultra-highly selective hydrogen sulfide imaging and elimination in vivo.

Lung injury is a hydrogen sulfide (H2S)-associated complication with high mortality in acute pancreatitis (AP) cases. Herein, we used Prussian Blue (PB) as a H2S-responsive acceptor to develop a novel pure-inorganic upconversion nanoprobe for detecting and eliminating H2S, which can be used for diagnosing AP and alleviating lung injury. Upconversion nanoprobes with 5 nm PB shells were optimized to achieve outstanding in vitro H2S detection capacity (linear range: 0-150 μM, LOD: 50 nM), which met the in vivo serum H2S range, and thus were feasible for imaging H2S in vivo. More importantly, when combined with the traditional H2S synthetase inhibitor dl-PAG, the nanoprobes also served as a therapeutic agent that synergistically alleviated lung injury. As PB is an FDA-approved drug, our work proposes a potential clinical modality for the early diagnosis of AP, which will decrease lung injury-induced mortality and increase the survival rates of AP cases.

Metal-organic framework nanosheets with flower-like structure as probes for H2S detection and in situ singlet-oxygen production.

Herein, a novel bifunctional flower-like metal-organic framework (MOF) was designed as a probe, which could be activated by H2S, induce itself disassembly and then release linker, Zn porphyrin. Therefore, the fluorescence of the system is enhanced and 1O2 could be produced in situ, opening up a new avenue for selective H2S detection under physiological pH and controllable 1O2 release.

In Operando Impedance Spectroscopic Analysis on NiO-WO3 Nanorod Heterojunction Random Networks for Room-Temperature H2S Detection.

The use of metal-oxide sensors for effectively detecting hydrogen sulfide (H2S) gas at room temperature is currently hindered by their inadequate sensitivity and selectivity. Using a lucid fabrication strategy, we report a room-temperature, highly sensitive, and selective H2S gas sensor using NiO-modified WO3 nanorod (one-dimensional–one-dimensional) random networks. The observed improvements in gas-sensing sensitivity stem from the synergistic effects of various contributions inside the sensing heterostructure, such as bulk nanorod, p–n heterojunction at the interface of these two dissimilar oxides, and gas-induced conducting species due to sulfurization (WS2–x and NiS1–x). An in situ impedance measurement during gas exposure was used to investigate the influence of these effects. The analysis revealed that these contributing factors can be either cooperating or competing and lead to either increased or decreased sensitivity, respectively. The presence of semimetallic species (NiS, WS2) was further confirmed by in situ X-ray diffraction analysis of the heterostructure nanorod sample with H2S gas exposure. The related sensing mechanism in the heterostructures is presented with a conduction pathway model. The room-temperature-operated nanorod heterostructure sensors showed a lower detection limit of H2S at ∼0.5 ppm, which is significantly lower than its toxicity limiting value ∼10 ppm, per the Environmental Protection Agency. The nanorod heterostructure sensors can be used for real-time, low-cost, room-temperature alarms in an H2S monitoring system.

Author Correction: Natural gas upgrading using a fluorinated MOF with tuned H2S and CO2 adsorption selectivity

In the version of this Article originally published, the name of author Gongping Liu was mistakenly written with the names in reverse order. This has now been corrected.

Selective Removal of H2S from Gas Streams with High CO2 Concentration Using Hollow‐Fiber Membrane Contractors

AbstractSelective and simultaneous separation of H2S and CO2 from CH4 was accomplished in a hollow‐fiber membrane contactor (HFMC). The absorption of both H2S and CO2 using an aqueous solution of methyldiethanolamine (MDEA) was almost complete and acid gases were totally removed. Despite the large difference between H2S and CO2 concentrations, the rate of H2S absorption was not significantly influenced by CO2 absorption. The independent effect and interactions of several process variables on the separation performance of H2S and CO2 were investigated. The results indicated that the membrane contactor could be a highly efficient choice for removal of almost all H2S in the presence of a large CO2 content even at high gas/liquid flow ratio. The selectivity of H2S was about three times higher compared to the conventional absorption packed towers.

Natural gas upgrading using a fluorinated MOF with tuned H2S and CO2 adsorption selectivity

The process used to upgrade natural gas, biogas and refinery-off-gas directly influences the cost of producing the fuel and often requires complex separation strategies and operational systems to remove contaminants such as hydrogen sulfide (H2S) and carbon dioxide (CO2). Here we report a fluorinated metal–organic framework (MOF), AlFFIVE-1-Ni, that allows simultaneous and equally selective removal of CO2 and H2S from CH4-rich streams in a single adsorption step. The simultaneous removal is possible for a wide range of H2S and CO2 compositions and concentrations of the gas feed. Pure component and mixed gas adsorption, single-crystal X-ray diffraction and molecular simulation studies were carried out to elucidate the mechanism governing the simultaneous adsorption of H2S and CO2. The results suggest that concurrent removal of CO2 and H2S is achieved via the integrated favourable sites for H2S and CO2 adsorption in a confined pore system. This approach offers the prospect of simplifying the complex schemes for removal of acid gases. Contaminants such as CO2 and H2S present in natural gas and biogas streams must be removed before use; existing strategies to do so can be rather complex. Here, the authors use a fluorinated porous metal–organic framework to remove CO2 and H2S from CH4-rich feeds in a single step, potentially simplifying the process.