Adsorption Of Hydrogen Sulfide Research Articles

Adsorption of hydrogen sulfide in biogas using a novel iron-impregnated biochar scrubbing system

Hydrogen sulfide (H2S) in biogas is produced during anaerobic digestion of organic wastes and can lead to corrosion of generators used for energy production. Recently, there has been interest in utilizing biochar as a substitute for activated carbon (AC) to adsorb and remove H2S from biogas. This study was the first to test iron (Fe)-impregnation of biochar to increase H2S removal from biogas using a biogas scrubbing column. Two biochar substrates, corn stover biochar (CSB) and maple wood biochar (MB), with and without Fe-impregnation were evaluated for H2S adsorption from biogas. The H2S adsorption capacity was quantified using dynamic breakthrough experiments. Iron-impregnated maple biochar (MB-Fe) had the highest H2S saturation adsorption capacity (23.9 mg H2S g−1 biochar), which was 3.9 times higher than the unmodified MB (6.1 mg H2S g−1 biochar). The Fe-impregnated corn stover biochar (CSB-Fe) saturation H2S sorption capacity (8.2 mg H2S g−1 biochar) was 2.5 times higher than the unmodified CSB (3.3 mg H2S g−1 biochar). The presence of iron oxide (Fe3O4) was observed through X-ray diffraction and scanning electron microscopy in the Fe-impregnated biochar substrates, with ferrous sulfate (FeSO4) as one of the end products in the saturated biochar surface and elemental sulfur in the pores. The study showed how Fe-impregnation can result in a multifold increase in H2S adsorption from biogas compared to unmodified biochar.

IRMOF‐8: Theoretical evaluation of aluminum doping on hydrogen, methane, and hydrogen sulfide adsorption

AbstractThe use of porous materials, aimed at increasing gas storage capacity at lower pressures, exploits physical adsorption and is an emerging strategy that is being widely investigated. In this scope, porous materials such as metal organic frameworks (MOFs) are a viable alternative, where structural modifications can enhance the properties of these materials and improve the degree of adsorption for a given gas. In this work, we evaluated the adsorption of methane, hydrogen, and hydrogen sulfide gases on pure isoreticular MOF (IRMOF)‐8 and aluminum‐doped IRMOF‐8 using density functional theory Perdew‐Burke‐Ernzerhof/DZVP and semiempirical AM1, PM3, PM6, PM6‐DH+, PM6‐DH2, PM6‐D3, and PM7 methods. Adsorption isotherms were calculated by means of Grand Canonical Monte Carlo simulations. It was found that doping did not provide a significant increase in the amount of adsorbed methane and hydrogen gases. Conversely, doping led to a considerable increase for hydrogen sulfide capture.

Hydrogen Sulfide Adsorption by Iron Oxides and Their Polymer Composites: A Case-Study Application to Biogas Purification.

An experimental study of hydrogen sulfide adsorption on a fixed bed for biogas purification is proposed. The adsorbent investigated was powdered hematite, synthesized by a wet-chemical precipitation method and further activated with copper (II) oxide, used both as produced and after pelletization with polyvinyl alcohol as a binder. The pelletization procedure aims at optimizing the mechanical properties of the pellet without reducing the specific surface area. The active substrate has been characterized in its chemical composition and physical properties by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), thermogravimetric analysis (TGA) and N2 physisorption/desorption for the determination of surface area. Both powders and pellets have been tested as sorbents for biogas purification in a fixed bed of a steady-state adsorption column and the relevant breakthrough curves were determined for different operating conditions. The performance was critically analyzed and compared with that typical of other commercial sorbents based on zinc oxide or relying upon specific compounds supported on a chemically inert matrix (SulfaTreat®). The technique proposed may represent a cost-effective and sustainable alternative to commercial sorbents in conventional desulphurization processes.

Achieving Dual-Functionality by Surface Coating of Zeolite with Stearic Acid: Combining Breathability and Odor Control Properties in Polyethylene/Zeolite Composite Films

This study was aimed at providing both water vapor permeability and hydrogen sulfide adsorption properties in polyethylene (PE) stretched films by using different amounts of natural zeolites. Firstly, zeolite was coated with 1%, 5%, and 7% stearic acid in a high shear mixer. Cup test, Fourier transform infrared (FTIR) spectroscopy, and ash-oven analyses showed that a succesful coating was achieved. According to the Brunauer, Emmett and Teller (BET) gas adsorption and inductively coupled plasma mass spectrometer (ICP-MS) analyses, surface treatment with stearic acid didn’t change the particle size of the zeolite but lowered its hydrogen sulfide (H2S) adsorption capacity from 38.84±5.22 ppm/g sample (uncoated zeolite) to 17.26±2.54 ppm/g sample (7% coated zeolite]. PE/zeolite (80/20 and 60/40 w/w] blown films were generated by using uncoated and 1%, 5%, and 7% stearic acid coated zeolites and then stretched. It was observed that the stearic acid coating of zeolite greatly improved the compatibility between polyethylene and zeolite resulting in films without pinholes generation after stretching (especially the 7% coated zeolite containing PE/zeolite (60/40 w/w) film). The usage of coated zeolite also improved mechanical properties by increasing the tensile strength and decreasing the elongation at break values. It was revealed that a loading amount of 40 wt% coated zeolite was necessary for achieving a sufficient breathability (658±4 and 1040±3 g/m2/day for 5% and 7% coated zeolite containing films, respectively). Odor removal capacity of the PE/zeolite (60/40 w/w) films was improved by 165% and 244% for the 5% and 7% coated zeolite containing samples, respectively.

Adsorption of hydrogen sulfide (H2S) by BaFe2O4-activated clay nanocomposite: preparation and evaluation

AbstractIn this study, BaFe2O4–activated clay nanocomposites were successfully synthesized via mechanosynthesis technique for the first time. Structural analysis of the products confirmed the nanoscale formation of nanocomposites. This study focused on adsorption of hydrogen sulfide (H2S) which is a poisonous gas and can be released from sewage sludge. Formation of nanocomposites was verified by scanning electron microscopy (SEM), energy dispersive X-ray (EDS) analysis, Fourier transform infrared (FTIR) and X-ray powder diffraction (XRD). Results showed that different loadings of barium ferrite in the nanocomposite were important for the adsorption rate. Furthermore, adsorption rate of hydrogen sulfide was improved by increasing BaFe2O4- activated clay concentration which was confirmed by statistical results. The highest average of removal efficiency was 92.79±0.90 in the concentration of 300 g.L-1and the loading of 6%. We could recycle BaFe2O4–activated clay nanocomposite 3 times without a significant decrease in activity. Enhanced performance of BaFe2O4–activated clay, compared to other nanocomposites, recommends its application for adsorptive desulfurization.

Adsorption and dissociation mechanism of hydrogen sulfide on layered FeS surfaces: A dispersion-corrected DFT study

The surface properties of various layered FeS surfaces were calculated using dispersion-corrected density functional theory (DFT-D2). The calculations indicated that FeS(001) was the most surface. The most stable adsorption sites of H2S and its dissociation products on the different layered FeS surfaces were determined, and the activation energy (Ea) and reaction heat (ΔE) of H2S dissociation were calculated. Our results showed that the adsorption energy (Eads) of H2S on the investigated surfaces increased in the order FeS(111) < FeS(100) < FeS(011) < FeS(001). The complete dissociation of H2S was most favorable on the FeS(011) surface with an Ea and ΔE of 0.10 and 0.26 eV, respectively. The dissociation reaction of H2S essentially did not occur on the (001) surface, while partial dissociation was observed on the (111) surface. These calculations demonstrated that the different dissociation behavior of H2S on the different surfaces was related not only to the electronic properties of the surfaces, but also to the adsorption configurations of the transition states. These findings increase our understanding of the electronic structure, relative stability, and surface bonding of various FeS surfaces, and also have reference value for related processes such as friction lubrication, heterogeneous catalysis, and biological systems.

Hydrogen sulfide removal from biogas using ion-exchanged nanostructured NaA zeolite for fueling solid oxide fuel cells

Hydrogen sulfide is the most abundant sulfur compound in the biogas, and in order to use for fueling the solid oxide fuel cells, its content should be less than 1 ppm. In this work, NaA nano zeolite is synthesized hydrothermally and modified by Ag+ ions, and its breakthrough capacity for hydrogen sulfide adsorption was measured using dynamic lab-scale adsorption tests on the experimental set-up for the first time. The results are compared to those of unmodified NaA nano zeolite and micron-sized commercial 4A zeolite. AgNaA nano zeolite showed the highest adsorption capacity (33.24 mg H2S/g of Sorbent) and the longest breakthrough time (310 min). The regeneration performance of AgNaA nano zeolite and its structural stability are also investigated after five cycles. The results revealed that the AgNaA nano zeolite could be used promisingly for removing hydrogen sulfide from biogas for cleaner energy production.

Synthesis of novel and engineered UiO-66/graphene oxide nanocomposite with enhanced H2S adsorption capacity

Herein, in order to desulfurize the gas streams and assist in the environmental protection, a novel nanocomposite adsorbent was synthesized. To this end, the Zr-metal organic framework (UiO-66)/graphene oxide (GO) nanocomposites were synthesized by employing different GO contents (3, 7, and 10 wt%) for hydrogen sulfide (H2S) adsorption in a dynamic adsorption system at 30, 40 and 50 °C. The prepared nano-adsorbents were characterized by TEM, SEM, BET, FTIR, and TGA techniques. The H2S absorption capacity of the ZMGO nanocomposites and the pristine UiO-66 were measured. The H2S adsorption results revealed that the adsorption capacities of H2S on the prepared nanocomposites were much better than the pristine UiO-66 adsorbent. The ZMGO-3 nanosorbent resulted in the maximum H2S uptake of 8.7 mmolS/g at 30 °C due to higher surface area and the micropore volume, which was about 3 times higher than that of the UiO-66. Finally, the repeated adsorption/desorption experiments clarified that the adsorption capability of ZMGO-3 was approximately stable along with a 10-15% reduction of the H2S adsorption capacity H2S after 3 cycles.

Adsorption of H2S from Hydrocarbon Gas Using Doped Bentonite: A Molecular Simulation Study.

Hydrogen sulfide is a commonly occurring impurity in hydrocarbon gases such as natural gas or landfill gas. Apart from its toxicity, H2S can cause problems in downstream processing because of corrosion of piping in the presence of moisture. Removing this contaminant using a cost-effective and energy-efficient technique such as adsorption using commonly occurring adsorbents would be beneficial both for processing and refinement of hydrocarbon gases and for their use as an energy source. In this work, grand canonical Monte Carlo simulations were performed using an ab initio forcefield to predict adsorption isotherms for methane, hydrogen sulfide, and nitrogen in bentonite doped with K+, Li+, and Na+ cations with a view to aiding the development of low-cost pressure-swing adsorption systems for the targeted removal of H2S from landfill gas or natural gas. Pure species simulations were done, in addition to considering mixtures at conditions approximating real-world natural gas fields. Highly selective targeted adsorption of hydrogen sulfide was achieved for all three doped bentonites, with the adsorbed phase consisting of almost pure H2S, although the volume of gas adsorbed differed between adsorbents. The results suggest the following ranking for the three doped bentonite adsorbents in terms of their overall performance: K+ > Li+ > Na+. By considering both the composition of the adsorbed phase and the total quantity of adsorbed gas, there may be an interplay between the gas–gas and gas–solid interactions that becomes somewhat noticeable at low pressures.

On the impact of copper local environment on hydrogen sulfide adsorption within microporous AlPO4-5

This work aims at elucidating the most active modes of copper incorporation towards H2S adsorption. Various synthesis methodologies were followed, notably, incorporation via isomorphic substitution, liquid ion exchange (LIE), vapor phase ion exchange (VIE), and nanoparticles inclusion during hydrothermal synthesis, for the introduction of copper into AlPO4-5 and SAPO-5. Techniques such as XRD and SEM/EDX, TEM, FT-IR and N2 adsorption-desorption were employed to characterize the synthesized materials. The Cu- containing materials were examined as sorbents for H2S removal via breakthrough experiments at 150 °C. The highest sulfur removal capacity was attained over the CuO nanoparticles supported in AlPO4-5 (10 % CuO/AlPO4-5), followed by a copper-based material prepared by VIE (Cu-VIE-0.2), accounting for H2S breakthrough capacities of 0.31 and 0.17 mmol ∙ g−1, respectively. The superior performance of these two materials could be ascribed to the relatively higher copper loading in the form of CuO as confirmed by XRD. Comparing the capacity per gram of active site, it was revealed that positioning Cu ions in extra-framework sites leads to an order of magnitude enhancement. This can be attributed to the possibility of a Cu ion to interact with more than one H2S molecule simultaneously unlike the other incorporation modes examined. Furthermore, copper ions incorporated into the crystal framework were found to be inactive towards H2S adsorption.

Molecular dynamics simulation of H2S adsorption behavior on the surface of activated carbon

In the present study, the impact of presence of chloride molecules on activated carbon was assessed by locating chloride molecules in graphite pores, by which the adsorption of hydrogen sulfide on activated carbon can be investigated in either presence or absence of chloride molecules based on molecular simulation. As a result, increasing the amount of chloride molecules leads to decline in equilibrium adsorption capacity. Furthermore, the influence of temperature and pore width on hydrogen sulfide adsorption on the surface of activated carbon were also investigated. The simulation finding showed that because of decreasing pore width at low pressures, the adsorption capacity of hydrogen sulfide increases, while the equilibrium adsorption capacity decreases. Finally, three model of adsorption isotherm including Langmuir, Freundlich and Langmuir-Freundlich isotherms were examined for hydrogen sulfide adsorption, in which the Langmuir-Freundlich isotherm yielded the best.

Density functional theory study of hydrogen sulfide adsorption onto transition metal-doped bilayer graphene using external electric fields

The adsorption of hydrogen sulfide molecules onto bilayer graphene (BG) doped with transition metals (TM), such as V, Cr, Mn, Fe, Co, and Ni, was studied using external electric fields and density functional theory calculations. The adsorption of H 2 S onto TM-doped BG was significantly improved compared with adsorption onto pristine BG. An external electric field can promote the adsorption of H 2 S onto BG, and the stability of this adsorption increases with the intensity of the electric field. Typically, this stability is independent of the direction of the electric field (upward or downward). However, H 2 S is sensitive to the direction of the electric field, and a downward (negative value) electric field is more favorable for H 2 S adsorption onto TM-doped BG. The desorption of H 2 S molecules from TM-doped BG was achieved using an upward (positive value) electric field, and the maximum desorption effect occurred at an electric field intensity of approximately 0.2 V/Å. The adsorption of gas molecules was also observed to modify the electronic structures of the TM/BG systems. All the TM/BG-H 2 S systems demonstrated semiconductive characteristics with different band gaps, except for the V/BG-H 2 S system. Overall, the results of this study showed that TM-doped BG has potential applications to methods for the adsorption, storage, and detection of H 2 S gas. • The TM/BG systems can significantly improve the adsorption stability of H 2 S compared with pristine bilayer graphene. • The external electric field promotes the adsorption of H 2 S onto bilayer graphene. • The adsorption of H 2 S is sensitive to the direction of the electric field. • The desorption of H 2 S gas molecules from TM-doped bilayer graphene can be achieved using an upward electric field. • The adsorption of gas molecules modifies the electronic structures of the TM/BG systems.

Oxidization of hydrogen sulfide in biogas by manganese (IV) oxide particles

Hydrogen sulphide is corrosive to most metallic equipment such as pipelines, compressors, gas storage tanks, engines, turbines and other units. It acts as a strong poison for fuel cells and its combustion leads to SO2 emissions. Due to the problems associated with hydrogen sulphide, it is critical to remove it from biogas before further processing. The removal of hydrogen sulphide from biogas using MnO2, which acts as a sorbent and catalyst, was investigated. The research was conducted in a full-scale agriculture biogas plant using chicken manure and maize silage as substrate. The manganese dioxide (manganese (IV) oxide) was derived from the waste products of a water conditioning system, after manganese removal from drinking water. The obtained results showed significantly better adsorption of hydrogen sulphide and faster regeneration of the bed compared to the bed filled with hydrated iron oxides. The H2S concentration in the treated biogas dropped from about 1,650 to 0-5 ppm.

Effective adsorption of hydrogen sulfide by intercalation of TiO2 and N-doped TiO2 in graphene oxide

In this research, hydrogen sulfide was adsorbed onto the TiO2/graphene oxide (TiO2/GO) nanohybrids. In this regard, the band gap energy of the TiO2 nanoparticles was altered through nitrogen doping which influence the chemical properties of the metal oxides. The nanoadsorbents were characterized before and after adsorption of H2S. The effect of the temperature (200−220 °C) on the H2S adsorption capacity was examined. The results showed that the increase in the temperature had a positive effect on the adsorption of H2S for all of TiO2/GO hybrid nanoadsorbents. The optimum breakthrough capacities for 5%TiO2/GO, 10 %TiO/GO and 5%N-TiO2/GO was obtained at 220 °C as 0.25, 0.20 and 0.17 gS/g sorbent, respectively. The 5%N-TiO2/GO was found to be the best nanoadsorbent due to its lower band gap, higher surface area, synergic effects and presence of active sites of N-TiO2 over the nanoadsorbents. The H2S uptake capability of the 5%N-TiO2/GO nanoadsorbent was reduced to about 30–60 % after 2 regeneration cycles due to the chemisorption.

Effect of iron salt modification on the adsorption of hydrogen sulfide by sludge-based activated carbon

Effect of iron salt modification on the adsorption of hydrogen sulfide by sludge-based activated carbon

Adsorption of acetic acid and hydrogen sulfide using NaOH impregnated activated carbon for indoor air purification

Excessive exposure to hydrogen sulfide (H2S) and acetic acid (CH3COOH) gases is extremely dangerous in a confined space. An effective indoor air pollutant removal porous carbon filter was developed using NaOH impregnated on activated carbon (NaOH/AC) for the adsorption of H2S and CH3COOH. Activated carbon (NaOH/AC) filter was characterized using various methods, indicating good physical and chemical properties (especially ‐OH functional groups) for the adsorption of air pollutants. The prepared NaOH/AC filter was cured at different curing temperatures and residence times to understand the effect of the curing conditions on the adsorption performance. The best results were obtained with NaOH/AC filter cured at 100°C for 20 minutes as it eliminated the initial concentration of 400 ppm of CH3COOH in 15 minutes and H2S in 30 minutes at 20°C and 60% relative humidity. Isotherm and kinetic models were used to analyze the adsorption process. Langmuir isotherm and pseudo‐second order kinetic models provided the best fit to the adsorption of CH3COOH and H2S on NaOH/AC filter. The adsorption mechanism was controlled by the intraparticle diffusion combined with film diffusion. The maximum adsorption capacity of NaOH/AC filter was 473 mg/g for H2S adsorption, and 550 mg/g for CH3COOH adsorption. In addition, the spent NaOH/AC filter was regenerated for reuse. This study is expected to develop low‐cost and effective porous carbon filter using NaOH‐modified activated carbon for indoor air purification.

Effect of ultramicropores on the mechanisms of H2S retention from biogas

The pore distribution in activated carbon is crucial for its performance on adsorption processes. In desulfurization applications, the literature highlights the importance of pores from 5 to 10 Å. However, little is known and reported about the range of ultramicropores smaller than 4 Å, which has been found in commercial samples used for H2S retention. In order to clarify the influence of this fraction of pores on the H2S retention of typical biogas mixtures, measurements of multicomponent adsorption of hydrogen sulfide in the presence of carbon dioxide for activated carbon samples further impregnated with potassium hydroxide have been performed in column dynamics. Molecular simulation, XRF analysis and textural characterization were applied to aid the study. Results have shown that the H2S retention capacity in the presence of CO2 decreased significantly mainly in the impregnated samples. The degree of reduction in H2S retention indicates that ultramicropores can be of substantial importance through a synergistic immobilizing effect of H2S molecules. The better understanding of such an effect could improve the development of more efficient adsorbents for chemical industries.

The adsorption of hydrogen sulfide in calcite pores: A molecular simulation study

The adsorption of hydrogen sulfide in gas reservoir cores is important to natural gas industry for predicting the sulfur content. Here, the adsorption of hydrogen sulfide in the calcite pore is investigated using molecular simulations. The results show that the absolute adsorption amount of H2S increases with the increasing of the pressure. However, the absolute adsorption amount decreases with the increasing of temperature. The adsorption capacity of H2S on the calcite surface can be well described by the combination of Langmuir equation and Clausius-Clapeyron equation. In order to investigate the effect of hydrogen bond on adsorption, a method of computing the hydrogen bond of H2S is proposed. The number of the average hydrogen bond per H2S molecules increases with the increasing of pressure. Furthermore, the existence of calcite surface will affect the distribution of hydrogen bond. This will order the structures of H2S molecules near the calcite surface and break the hydrogen bonds.

Influence of the coal-derived synthesis gas composition on the thermal stability of ZnO sorbents in the desulfurization process

The priority direction of thermal energy on solid fuels is to increase efficiency and environmental safety, approaching zero emissions of harmful substances. To achieve these goals, they are currently creating new schemes for combined cycle gas turbine units with intra-cycle gasification (IGCC). To improve the efficiency of the IGCC cycle, hot dry desulfurization (HGC) technologies are being developed. HGC uses regenerable sorbents that allow the repeated adsorption of hydrogen sulfide from synthesis gas, among which the most acceptable thermodynamic and operational characteristics are based on ZnO sorbents. The article uses the method of thermogravimetric analysis (TGA) to investigate the development of target reaction capture hydrogen sulfide ZnO-containing sorbent and sorbent reactions with components of synthesis gas in the temperature range up to 1000°C. The sorbent calcined at 900°C shows thermal stability in an inert atmosphere over the entire temperature range studied. Uncalcined sorbents at temperatures of 200 and 600°C emit carbon dioxide in an amount of 1.5-4.5% by weight of the sorbent. At temperatures up to 550°C, the target reaction is basic, and side reactions practically do not develop. The maximum rate of absorption of hydrogen sulfide by the sorbent is observed at a temperature of 600°C. At 500-550°C reactions of a sorbent begin with H2 and CO, at 750-800°C – with carbon, at 850°C – with CH4. The intensity of effect of reagents is defined on degradation of a sorbent by reactionary ability of gases more than temperature.

Adsorption of hydrogen sulfide by amine-functionalized metal organic framework (MOF-199): An experimental and simulation study

A series of amine modified MOF-199 adsorbents were prepared by impregnation method for using H2S room temperature removal. The parent and functionalized materials were characterized by XRD, FT-IR, SEM, N2 adsorption/desorption isotherms, and XPS. It was indicated that the structure of MOF-199 can be maintained after modification by appropriate tertiary amine triethanolamine (TEA), while primary amine monoethanolamine (MEA) and secondary amine diethanolamine (DEA) modification can destroy its structure due to the strong interaction with MOF-199. Breakthrough results showed that MOF-199 functionalized by TEA presented an improved H2S adsorption capacity of 2.74 mmol/g, higher than that of parent MOF-199 (1.67 mmol/g). Whereas, grafting of MEA and DEA into MOF-199 led to the sulfur capacity decrease to 0.83 mmol/g and 0.58 mmol/g, respectively. Calculation by density functional theory revealed that the binding energies of H2S adsorption on the TEA/MOF-199 were larger than that on bare MOF-199, which was considered to contribute to the improved adsorption. The enhanced binding energy of H2S on the TEA/MOF-199 was attributed to the hydroxyl in TEA.