Selective Absorption Of H2S Research Articles

Selective absorption of H2S and CO2 from simulated coke oven gas by aqueous blends of N-methyldiethanolamine and tetramethylammonium glycine

Selective absorption of H2S and CO2 from simulated coke oven gas by aqueous blends of N-methyldiethanolamine and tetramethylammonium glycine

Selective absorption of H2S and CO2 by azole based protic ionic liquids: A combined density functional theory and molecular dynamics study

To achieve efficient carbon capture, utilization, and storage, it is necessary to separate CO2 from the atmosphere. In an attempt to move towards selective separation of CO2, some of us have shown that ionic liquids (ILs) can be efficiently used to separate CO2 and H2S from CH4 and H2O. In the present work, we perform Density Functional Theory and Molecular dynamics simulations for four different ILs: [DBNH][1,2,3-triaz], [DBNH][1,2,4-triaz], [DBUH][1,2,3-triaz] and [DBUH][1,2,4-triaz]. DFT calculations have unveiled the additional selective character of H2S with respect to CO2. Whereas CO2 binds to the nitrogen of the anionic moiety of the IL forming a new CN bond, H2S transfers a proton to one of the nitrogen atoms of the IL with the consequent generation of a HS- anion. Radial distribution function analysis shows the presence of hydrogen bonds between cation and anion in neat ILs as well in presence of gases. Hydrogen bond analysis shows higher number of hydrogen bonds in the ILs between cation and the [1,2,3-triaz] anion as compared to [1,2,4-triaz] anion. Molecular dynamics simulations also show that these ionic liquids have stronger interaction with CO2 and H2S as compared to CH4. Overall, our study confirms the usage of studied ILs to efficiently capture CO2 and H2S.

Selective absorption of H2S from CO2 using sterically hindered amines at high pressure

Selective absorption of H2S from gas mixture containing H2S and CO2 into aqueous solutions of 2–(tert–butylamino) ethanol (TBE) and 2–amino–2–methyl–1–propanol (AMP) at different temperature was investigated at high pressure by using a static gas absorption method. The influence of temperature and contact time on the absorption of H2S was investigated. The rates of absorption of H2S and the selectivity factor decreased with the increase of absorption temperature. With increasing contact time for both alkanolamine solutions, the selectivity factor increased at first and then decreased.

Highly efficient and selective absorption of H2S in phenolic ionic liquids: A cooperative result of anionic strong basicity and cationic hydrogen-bond donation

A series of phenolic ILs containing different cations were synthesized and investigated for the absorption of H2S and CO2 in this work. It is interestingly found that the solubilities of H2S in these phenolic ILs are comparably high because of the strong interaction of basic phenolate anion with acidic H2S, while the solubilities of CO2 decrease significantly with the increase of cationic hydrogen-bond donation. Tetramethylguanidinium phenolate ([TMGH][PhO]), which is constructed with anion of strong basicity and cation of strong hydrogen-bond donating ability, is thus highlighted with both high solubilities of H2S (0.56mol/mol at 313.2K and 0.1bar, and 0.85mol/mol at 313.2K and 1bar) and high selectivities of H2S/CO2 (6.2 for the ratio of H2S solubility at 313.2K and 0.1bar vs. CO2 solubility at 313.2K and 1bar, and 9.4 for the ratio of H2S solubility at 313.2K and 1barvs. CO2 solubility at 313.2K and 1bar). Owing to the small molecular size of [TMGH][PhO], the absolute solubilities of H2S in it (2.68mol/kg at 313.2K and 0.1bar, and 4.08mol/kg at 313.2K and 1bar) are particularly fascinating, and much higher than other absorbents reported in the literature. Furthermore, [TMGH][PhO] is cost-effective in comparison with other functionalized ILs specifically designed for H2S capture, since it can be facilely synthesized from the one-step neutralization of readily available 1,1,3,3-tetramethylguanidine and phenol. The results obtained in this work indicate that [TMGH][PhO] is a promising candidate for the selective sweetening of natural gas.

Hydrophobic protic ionic liquids tethered with tertiary amine group for highly efficient and selective absorption of H2S from CO2

Developing absorbents with both high absorption capacity of H2S and large selectivity of H2S/CO2 is very important for natural gas sweetening process. To this end, a class of novel hydrophobic protic ionic liquids (ILs) containing free tertiary amine group as functional site for the absorption of H2S were designed in this work. They were facilely synthesized through a simple neutralization‐metathesis methodology by utilizing diamine compounds and bis(trifluoromethylsulfonyl)imide as the building blocks for cation and anion, respectively. Impressively, the solubility of H2S can reach 0.546 mol mol−1 (1 bar) and 0.225 mol mol−1 (0.1 bar), and the selectivity of H2S/CO2 can reach 37.2 (H2S solubility at 1 bar vs. CO2 solubility at 1 bar) and 15.4 (H2S solubility at 0.1 bar vs. CO2 solubility at 1 bar) in the hydrophobic protic ILs at 298.2 K. Comparing the hydrophobic protic ILs with other absorbents justifies their superior performance in the selective absorption of H2S from CO2. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4480–4490, 2016

Investigating the Effect of Operating Temperature on the Performance of TGT Absorber Column

Hydrogen sulfide (H2S) coming from oil and gas refineries, after purifying in amine sweetening unit, is routed to Sulfur Recovery Unit (SRU), wherein converted to elemental sulfur. In order to compensate the low performance of SRU, the remained acid gas is then fed to Tail Gas Treatment (TGT) unit for more processing. TGT unit increases the overall sulfur recovery and therefore, decreases the environmental pollution. The absorber column is an important equipment in the TGT unit. The main function of this column is the selective absorption of H2S in the presence of CO2. In this paper, the effect of operating temperature on the performance of TGT absorber column will be investigated. For this purpose, a typical industrial TGT unit is simulated and then, the results are illustrated and analyzed in terms of technical points of view.

Selective absorption of H2S from a gas mixture with CO2 in a microporous tube-in-tube microchannel reactor

In industrial gas processing, there is an increasing interest in gas absorption processes for the selective removal of H2S from gas streams with a high CO2/H2S ratio. In this work, the selective absorption of H2S from a gas mixture with CO2 into N-methyldiethanolamine (MDEA) in a microporous tube-in-tube microchannel reactor (MTMCR) was studied. A high H2S removal efficiency of 99.85% could be achieved. The effects of various parameters such as MDEA concentration, liquid and gas flow rates, gas–liquid ratio, absorbent temperature, mean micropore size and annular channel width of MTMCR on H2S removal efficiency and selectivity were explored. The results indicated that MDEA concentration, liquid and gas flow rates had significant influence on H2S removal efficiency and selectivity. With the increase of MDEA concentration and liquid flow rate, H2S removal efficiency increased while selectivity decreased. Increasing gas flow rate resulted in H2S removal efficiency decrease and the selectivity increase. The smaller micropore size and annular channel width led to higher H2S removal efficiency and lower selectivity. Furthermore, the micropore size had a bigger effect on H2S selective removal process than the annular channel width. The results obtained imply a great potential for MTMCR applied to the selective absorption of H2S.

Selective Absorption of H2S from a Gas Mixture with CO2 by Aqueous N-Methyldiethanolamine in a Rotating Packed Bed

In this work, selective absorption of H2S from a gas mixture with CO2 into N-methyldiethanolamine (MDEA) is investigated experimentally and theoretically in a rotating packed bed (RPB). In the RPB, various rotating speeds, gas flow rates, liquid flow rates, and concentrations of MDEA aqueous solutions were studied by means of the evaluation of removal efficiency, selectivity, and overall volumetric mass transfer coefficient. The reaction−diffusion mass transfer model based on penetration theory for the selective absorption process is developed, accordingly. The results of experiment and model show that the uppermost function of RPB in selective absorption of H2S is to restrain the CO2 removal efficiency but sharply intensify the absorption of H2S. The mass transfer coefficient of CO2 absorption is enhanced in RPB. However, the total amount of CO2 mass transfer virtually is low because of the short gas−liquid contact time, small volume of packing, and large gas−liquid ratio within the RPB, and the CO2 remo...

Selective absorption of H2S from gas streams containing H2S and CO2 into aqueous solutions of N-methyldiethanolamine and 2-amino-2-methyl-1-propanol

Selective absorption of H2S from N2 streams containing H2S and CO2 into aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) as well as N-methyldiethanolamine (MDEA) was investigated in a 2.81×10−2 m o.d. stainless steel wetted-wall column at atmospheric pressure and constant feed gas ratio. In the range of gas flow rates studied (90–180×10−6 m3/s), the effect of gas-phase resistance on the absorption of H2S was significant. The rates of absorption of H2S and the selectivity factor decreased with the contact time for both alkanolamine solutions. With increasing amine concentration in the range 2.0–3.0 kmol/m3, the rates of absorption of both CO2 and H2S increased, but relatively more for CO2, resulting in a consequent decrease in the selectivity factor. In the temperature range 293–313 K, the rates of absorption of CO2 increased marginally with the increase in temperature while the rates of absorption of H2S and the selectivity factor decreased. The maximum selectivity observed in this work was 17.57 and 23.02 for AMP and MDEA, respectively. The acid gas mass transfer has been modelled using equilibrium-mass-transfer-kinetics-based combined model for CO2 and gas-phase transport equation-based approximate model for H2S considering negligible interaction between CO2 and H2S in the liquid phase. The experimental and model results have been found to be in good agreement.

Selective Absorption of H2S From Sour Gas

Selective absorption of H2S from sour gas with caustic by gas/liquid scrubbing is a new approach for oilfield operations to meet environmental and safety restrictions. This technology demonstrates that by maintaining a very short contact time in a gas/liquid scrubber it is possible for caustic to react with and remove H2S from a sour gas. Introduction Hydrogen sulfide (H2S) and carbon dioxide (CO2) are natural contaminants of gases from well casings, combustion floods, geothermal steam, or process streams. Because of safety, environmental or corrosion considerations, it normally is desirable to remove the H2S from such gases. However, these factors do not dictate the removal of CO2, and it is not desirable because of the cost involved. Safety standards set by the U.S. Occupational Safety and Health Admin. limit worker exposure to H2S at 10 ppm for an 8-hour day. Environmental guidelines ppm for an 8-hour day. Environmental guidelines require limited sulfur emissions, particularly of H2S, which has a characteristic "rotten egg" odor at levels of 3 ppm. Corrosivity of wet H2S gases is well known because of its acidic character. Many commercial methods exist to remove H2S from sour gas streams, though they all have their limitations. Some processes may be limited by the volume of gas they can handle or by the level of H2S or CO2 in the gas stream. Others may prove to be costly because of the capital investment or operating expense. Still others are not suitable for the field because of the complexity of operation, requiring highly trained personnel. In the H2S removal system described in this paper, these objections largely are overcome, as evidenced by a number of production units based on this technology. Experience has shown that this system (1) has a very low capital investment cost (2) has a simple design based on gas/liquid scrubbing (3) has straightforward installation and operation (4) will remove H2S efficiently, and (5) can treat gases widely varied in composition and volume. These units have proved effective in H2S removal from operations as widely divergent as pipeline-quality gas plants to remote locations treating vent gases with plants to remote locations treating vent gases with 10% H2S. Theory The principle of the technology presented here is based on a patent issued to The Dow Chemical Co. It states (and is reduced to practice in the method discussed here) that H2S can be absorbed selectively from sour gases also containing CO2 by maintaining a proper residence contact time between the gas and an alkaline liquid. Normally, in a typical wet scrubbing operation both acidic gases (H2S and CO2) would be absorbed. However, the absorption and reaction of H2S in a strongly alkaline solution (caustic soda) is virtually instantaneous while the absorption of CO2 is a much slower reaction. Thus, if the gas is allowed to contact the liquid for a controlled short time, the CO2 absorption and reaction with caustic will be insignificant. Because H2S does not have this limitation, it is absorbed preferentially. preferentially. JPT P. 1083