Adsorption Of Hydrogen Sulfide Research Articles

Adsorption of hydrogen sulfide over a novel metal organic framework –metal oxide nanocomposite: TOUO-x (TiO2/UiO-66)

TOUO-x nano-composites (TiO2/UiO-66 as with x: 1, 3 and 5 wt% of TiO2) are synthesized using hydrothermal method and characterized by FT-IR, XRD, FE-SEM, BET, and TGA analyses. The sulfur removal performance of prepared nano-composites is then evaluated and compared with pure UiO-66 by changing the temperature from 30 to 50 °C under space velocity of 30000 h−1 and H2S concentrations of 4000 ppm in the gas stream. TOUO-1% is illustrated as the best nano-composite adsorbent due to the higher BET surface area (1171 m2/g) in contrast to TOUO-3 (986 m2/g) and TOUO-5 (652 m2/g). In addition, the introduction of metal active sites of titanium is associated with the improved properties of synthesized nano-composite adsorbents in contrast to UiO-66. The sulfur-uptake capability of TOUO-1% has only reduced to about 3–5% after 2 cycles of hydrogen sulfide adsorption. The superior advantages of TOUO-x nano-composites, such as desulfurization uptake at low sulfur concentration range, excellent reusability, operation at mild conditions, and facile and low-cost nanocomposite synthesis make them as useful and economic adsorbents for removal of the sulfur component.

Modeling and simulation of adsorption of methane, ethane, hydrogen sulfide and water from natural gas in (FP)YEu Metal–Organic Framework

Metal Organic Frameworks (MOFs) are novel type of hybrid porous materials that have been proposed for natural gas separation and purification due to the possibility of tailoring their capabilities by changing the organic linkers, tuning the length of the organic linker and changing or mixing the metal ion. Molecular simulation helps to understand experimental results by providing a detailed picture on the molecular scale that is not easily accessible from experimental and can be used to study the applicability of classical force fields.In this work, FPYEu MOF [1] [2] was carefully chosen as an example of a model MOF for studying applicability of force fields, cutoff radius besides the effect of different distributions of metal ions in FPYEu MOF on adsorption of CH4, C2H6, H2S as well as H2O.Grand Canonical Monte Carlo (GCMC) simulations were used to perform gases adsorption on FPYEu MOF cells containing different distributions of Yttrium and Europium. All simulations in this work have been carried out using Towhee code [3].The applicability of different force fields available in the literature was tested and some of them were applicable like H2S, where good agreement was found with experimental results, while others were not applicable, like CH4, C2H6 and H2O, where the calculated isotherms “over or under” estimated the experimental ones. In addition, eight different configurations having Eu atoms arbitrarily located in the system were explored to evaluate the sensitivity of distribution of metal ions.

Functionalized GaN/GaInN heterostructures for hydrogen sulfide sensing

Near-surface GaN/GaInN quantum wells (QWs) were investigated as optical transducers for the detection of hydrogen sulfide. The heterostructure sensors were grown by metal organic vapor phase epitaxy and later covered by a thin layer of Au by electron beam evaporation. The QW photoluminescence (PL) is sensitive to changes in the sensor surface potential. By the adsorption of hydrogen sulfide (H2S) on the Au cover layer, downward near-surface band bending results in an increase of the quantum confined Stark effect in the GaInN QW producing a red shift in its luminescence. Unexpectedly, an increase in PL intensity is also observed. A concentration of 0.01 parts per million of H2S in nitrogen has been successfully detected. This phenomenon may be helpful to detect trace amounts of H2S present in the human breath for early detection of diseases.

Comparison of the adsorption of H2S by ZnO–TiO2 and Ni–ZnO–TiO2 nanoparticles: An adsorption isotherm and thermodynamic study

AbstractNanoparticles were synthesized by the sol–gel method and evaluated for adsorption of hydrogen sulfide using a continuous fixed‐bed column. The effects of the parameters were examined, and the optimum values for nanoparticles were found to be mass of adsorbent 0.2 g, gas volume 5.7 L, flow rate 0.22 L min−1, and gas pressure 7 Psi at 12 °C. These conditions resulted in a maximum adsorption of H2S of 83.24% and 90.43% for ZnO–TiO2 and Ni–ZnO–TiO2 nanoparticles, respectively. The equilibrium data were best represented by the Freundlich isotherm. The thermodynamic parameters indicated that the adsorption was spontaneous and exothermic in nature.

Hydrogen Sulfide Adsorption improvement of Bayah Natural Zeolite

Hydrogen sulfide adsorption performance of sonicated natural zeolite in the Ferric chloride hexahydrate solution has been studied. In this research natural zeolite exposed with high intensity ultrasonic waves for 40 minutes, 80 minutes and 120 minutes. Qualitative analysis and characterization of modified zeolite carry out with X-ray diffraction, Infrared spectroscopy, BET adsorption desorption, LAS particle size analysis and scanning electron microscopy prior and after H2S adsorption. Natural zeolite phase are clipnotilolite and mordenite phase with 0.99%wt and 0.512 x 10-3 %wt respectively. By adding 5gr FeCl3.6H2O and ultrasonic exposure, zeolite chemical and physical properties such as chemical composition, particle size, surface area and pore radius are improved. Hydrogen sulfide %wt adsorption effectiveness showing that modified zeolite higher 70-117% comparing with unmodified zeolite.

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.

Roles of Oxygen Functional Groups in Hydrogen Sulfide Adsorption on Activated Carbon Surface: A Density Functional Study

The hydrogen sulfide (H2S) removal ability of activated carbon is closely related to surface oxygen groups, yet the roles of oxygen groups in the process of H2S adsorption on activated carbon have ...

Studies of hydrogen sulfide and ammonia adsorption on P- and Si-doped graphene: density functional theory calculations.

Studies of hydrogen sulfide (H2S) and ammonia (NH3) adsorption on phosphorus (P) and silicon (Si) doped graphene are performed by ab initio calculations using the periodic density functional theory (DFT). The P and Si incorporation in graphene distorts the unit cell altering the bond lengths and angles. Unlike the pristine, the phosphorus-doped graphene shows a metallic behavior, and the silicon-doped graphene is a semiconductor with an energy gap of 0.25eV. Moreover, the electronic properties of phosphorus-doped graphene may change with the adsorption of hydrogen sulfide and ammonia. However, the silicon-doped graphene only shows changes with the adsorption of hydrogen sulfide. In addition, the silicon-doped graphene exhibits chemisorption when interacting with ammonia. According to the obtained results, phosphorus-doped graphene is suitable as a gas sensor of hydrogen sulfide and ammonia, in contrast with the silicon-doped structure, which may be used as a sensor of hydrogen sulfide. Graphical Abstract Ammonia adsorption on Si-doped graphene.

Enhanced adsorptive removal of hydrogen sulfide from gas stream with zinc-iron hydroxide at room temperature

Bimetallic (zinc-iron) hydroxides adsorbent (Zn-Fe hydroxide) was effectively synthesized through co-precipitation of bivalent zinc and trivalent iron at room temperature. The influences of Zn/Fe molar ratio, pH of a mixing solution of precipitating reagents, and aging temperature on adsorption capacity were investigated to find the optimum condition of the synthesized adsorbent, of which experiment was designed by the one-factor-at-a-time method. Powdered activated carbon (PAC) was employed as the support material to provide an active site on the synthesized composites. An optimized Zn-Fe hydroxide with 10 wt% of PAC had a breakthrough adsorption capacity of 0.143 gH2S/g, which was much higher than that of either a pure Fe hydroxide or Zn hydroxide. The synergistic interaction between Zn and Fe affected the morphology and the surface structure of the synthesized adsorbent. After hydrogen sulfide adsorption, ZnS and FeS were observed by the Scanning electron microscope-Energy dispersive spectroscopy and X-ray photoelectron spectroscopy.

Adsorption of H<sub>2</sub>S Gas by Modified Diatomite and Leonardite

This research aimed to modify of diatomite and leonardite for adsorption of hydrogen sulfide (H2S) gas. The effect of chemical loading on surface modification was studied. Natural diatomite and leonardite were obtained through the natural deposits in Lampang Province, Thailand. Diatomite and leonardite were modified using chemical methods with calcination at 450 °C. The chemical composition and phase structure of adsorbents were characterized by X–Ray fluorescence spectroscopy (XRF) and X–ray diffraction (XRD), respectively. The morphology and disperse energy of the elements were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The functional group was identified by Fourier transform infrared spectroscopy (FT–IR). The efficiency of adsorption of H2S gas was studied. H2S gas in this study was synthesized by the chemical reaction between sodium sulfide (Na2S) and sulfuric acid (H2SO4). The concentration of hydrogen sulfide was measured by an H2S gas detector. The performance of the modified diatomite and leonardite for adsorption of H2S was compared. It was found that modified diatomite has better efficiency than modified leonardite for the adsorption of H2S gas. After modification process, the adsorption efficiency increased while the adsorption time decreased.

Sorption of natural gas in cement hydrate by Monte Carlo simulation

Concrete, a combination of cement, water, sand, and aggregates, is a ubiquitous engineering and construction material. This composite material is exposed to a wide variety of environmental conditions that can cause degradation, such as extremes of temperature, and exposure to corrosive substances. This study is concerned with the sorption of natural gas constituents and their mixtures in cement hydrate using atomistic Monte Carlo simulation in the grand canonical ensemble. Pure species sorption isotherms were generated at 273, 298, and 323 K for gas fugacities up to 103 kPa. Comparison of gas uptake and the isosteric heat of adsorption in cement was undertaken for all of the species in the study, and the influences of both temperature and gas fugacity on sorption characteristics were considered. The selectivity of adsorption of hydrogen sulphide in a natural gas blend was also considered, as it is typically responsible for the degradation of concrete infrastructure.

Adsorption kinetics and modeling of H2S by treated waste oil fly ash

ABSTRACTWaste oil fly ash (OFA) collected from disposal of power generation plants was treated by physicochemical activation technique to improve the surface properties of OFA. This synthesized material was further used for potential hydrogen sulfide (H2S) adsorption from synthetic natural gas. The raw OFA was basically modified with a mixture of acids (20% nitric acid [HNO3] and 80% phosphoric acid [H3PO4]), and it was further treated with 2 M potassium hydroxide (KOH) to enhance the surface affinity as well as surface area of synthesized activated carbon. Correspondingly, it enhanced the adsorption of H2S. Crystallinity, surface morphology, and pore volume distribution of prepared activated carbon were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses. Fourier transform infrared (FTIR) study was also performed to identify the functional groups during different synthesis stages of modified activated carbon. The Langmuir, Freundlich, Sips, and dual-site Langmuir (DSL) models were used to study the kinetic and breakthrough behavior of H2S adsorption over alkali-modified activated carbon. Modeling results of isotherms indicated that OFA has dual sites with high and low affinity for H2S adsorption. The Clark model, Thomas model, and Yoon-Nelson model were used to examine the effects of flow rate and inlet concentration on the adsorption of H2S. Maximum uptake capacity of 8.5 mg/g was achieved at 100 ppm inlet concentration and flow rate of 0.2 L/min.Implications: Utilization of worthless oil fly ash from power plant is important not only for cleaning the environment but also for solid waste minimization. This research scope is to eradicate one pollutant by using another pollutant (waste ash) as a raw material. Chemical functionalization of synthesized activated carbon from oil fly ash would lead to attachment of functional groups of basic nature to attract the acidic H2S. Such type of treatment can enhance the uptake capacity of sorbent several times.

Prediction of the monocomponent adsorption of H2S and mixtures with CO2 and CH4 on activated carbons

Monocomponent adsorption of hydrogen sulfide and multicomponent adsorption with CO2 and CH4 mixtures were predicted in two samples of commercial activated carbons. We perform Monte Carlo calculations in the grand canonical ensemble in representative slit-pores of each carbon material and proposed a new energy parameter for H2S-carbon interaction from experimental adsorption heat in selected activated carbons. Further analysis of adsorption in representative pores demonstrated the importance of ultramicropores in H2S retention and a cooperative effect of CO2 molecules favoring H2S adsorption. To the best of our knowledge this is the first time that a method based on molecular simulation is proposed to predict H2S adsorption on carbon. This study contributes to a better understanding of the role of pore size distribution and adsorption regimes in carbon materials.

Cover Feature: Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) ‐ Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer. (ChemPhysChem 17/2018)

Cover Feature: Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) ‐ Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer. (ChemPhysChem 17/2018)

Probing Metal-Organic Framework Design for Adsorptive Natural Gas Purification.

Parent and amine-functionalized analogues of metal-organic frameworks (MOFs), UiO-66(Zr), MIL-125(Ti), and MIL-101(Cr), were evaluated for their hydrogen sulfide (H2S) adsorption efficacy and post-exposure acid gas stability. Adsorption experiments were conducted through fixed-bed breakthrough studies utilizing multicomponent 1% H2S/99% CH4 and 1% H2S/10% CO2/89% CH4 natural gas simulant mixtures. Instability of MIL-101(Cr) materials after H2S exposure was discovered through powderX-ray diffraction and porosity measurements following adsorbent pelletization, whereas other materials retained their characteristic properties. Linker-based amine functionalities increased H2S breakthrough times and saturation capacities from their parent MOF analogues. Competitive CO2 adsorption effects were mitigated in mesoporous MIL-101(Cr) and MIL-101-NH2(Cr), in comparison to microporous UiO-66(Zr) and MIL-125(Ti) frameworks. This result suggests that the installation of H2S binding sites in large-pore MOFs could potentially enhance H2S selectivity. In situ Fourier transform infrared measurements in 10% CO2 and 5000 ppm H2S environments suggest that framework hydroxyl and amine moieties serve as H2S physisorption sites. Results from this study elucidate design strategies and stability considerations for engineering MOFs in sour gas purification applications.

Adsorption of Hydrogen Sulfide, Hydrosulfide and Sulfide at Cu(110) - Polarizability and Cooperativity Effects. First Stages of Formation of a Sulfide Layer.

Understanding the surface site preference for single adsorbates, the interactions between adsorbates, how these interactions affect surface site specificity in adsorption and perturb the electronic states of surfaces is important for rationalizing the structure of interfaces and the growth of surface products. Herein, using density functional theory (DFT) calculations, we investigated the adsorption of H2 S, HS and, S onto Cu(110). The surface site specificity observed for single adsorbates can be largely affected by the presence of other adsorbates, especially S that can affect the adsorption of other species even at distances of 13 Å. The large supercell employed with a surface periodicity of (6×6) allowed us to safely use the Helmholtz method for the determination of the dipole of the surface-adsorbate complex at low adsorbate coverages. We found that the surface perturbation induced by S can be explained by the charge transfer model, H2 S leads to a perturbation of the surface that arises mostly from Pauli exclusion effects, whereas HS shows a mix of charge transfer and Pauli exclusion effects. These effects have a large contribution to the long range adsorbate-adsorbate interactions observed. Further support for the long range adsorbate-adsorbate interactions are the values of the adsorption energies of adsorbate pairs that are larger than the sum of the adsorption energies of the single adsorbates that constitute the pair. This happens even for large distances and thus goes beyond the H-bond contribution for the H-bond capable adsorbate pairs. Exploiting this knowledge we investigated two models for describing the first stages of growth of a layer of S-atoms at the surface: the formation of islands versus the formation of more homogeneous surface distributions of S-atoms. We found that for coverages lower than 0.5 ML the S-atoms prefer to cluster as islands that evolve to stripes along the [1 0] direction with increasing coverage. At 0.5 ML a homogeneous distribution of S-atoms becomes more stable than the formation of stripes. For the coverage equivalent to 1 ML, the formation of two half-monolayers of S-atoms that disrupt the Cu-Cu bonds between the first and second layer is more favorable than the formation of 1 ML homogeneous coverage of S-atoms. Here the S-Cu bond distances and geometries are reminiscent of pyrite, covellite, and to some extent chalcocite. The small energy difference of ≈0.1 eV that exists between this structure and the formation of 1 ML suggests that in a real system at finite temperature both structures may coexist leading to a structure with even lower symmetry.

The influence of the pore size in Metal−Organic Frameworks in adsorption and separation of hydrogen sulphide: A molecular simulation study

The influence of the pore size in Metal−Organic Frameworks in adsorption and separation of hydrogen sulphide: A molecular simulation study

Application of Raman spectroscopy in chemical investigation of impregnated activated carbon spent in hydrogen sulfide removal process

We present an application of Raman spectroscopy for understanding the chemisorption catalytic processes occurred in impregnated activated carbon used in hydrogen sulfide (H2S) adsorption from biogas. Downstream of an H2S adsorption capacity study, conducted employing commercial carbon at different operating conditions as sorbent in a fixed bed flow reactor, spent carbon samples who returned suitable H2S removal performances were studied by means of Raman spectroscopy. Raman analysis showed that among all the H2S metal impregnates, copper was the chemical responsible for H2S adsorption, since observed Raman spectra exhibited a perfect overlapping with copper sulfide (CuS) signature. A further confirmation was given by a thermal decomposition test conducted through the Raman optical apparatus over an H2S-exposed carbon sample, by estimating anti-Stokes and Stokes Raman processes relative efficiency. Raman results turned out to be consistent with thermogravimetry tests results executed over the same spent carbon samples. The experiment witnesses the capability of Raman spectroscopy to determinate the chemical nature of compounds resulting from H2S adsorption, overcoming the lack in chemical information encountered by elemental techniques such as energy-dispersive X-ray. We thus propose Raman spectroscopy as a way to integrate traditional chemical investigation procedures.

The influence of the pore size in Metal−Organic Frameworks in adsorption and separation of hydrogen sulphide: A molecular simulation study

Metal Organic Frameworks (MOFs) have the potential to be used as adsorbents in industrial separations. Different ligand lengths can generate MOFs with similar topology but differing pore sizes. Molecular simulations were used in this work to assess the adsorption isotherms, heats of adsorption and selectivity of H2S and CH4 in MOF UiO-66, UiO-67, and UiO-68. Detailed analysis of the distribution of molecules in the cages and the radial distribution functions suggest that the effect of the linker on the macroscopic properties is negligible at low pressures, but it becomes evident at high pressures, where adsorption far from the linker is observed in large pore materials. Based on the adsorption selection parameter, UiO-67 shows better performance in a wider range of conditions than the other materials.

Hydrogen sulfide adsorption by zinc oxide-impregnated zeolite (synthesized from Malaysian kaolin) for biogas desulfurization

The adsorption of hydrogen sulfide (H2S) from the gas stream in a fixed-bed reactor has been investigated using zinc oxide (10–30wt% loading) impregnated on Na-A zeolite prepared from local kaolin. The adsorbents obtained were characterized by XRF, XRD, FTIR, nitrogen adsorption and SEM. Reductions of micropore surface area and micropore volume of Na-A zeolite were observed after modification with zinc oxide. H2S adsorption capacity was the highest, 15.75mgS/g sorbent, when 20wt% ZnO was loaded on Na-A zeolite. Reduction in adsorption capacity was observed when wt% ZnO increased above 20wt%.