Selective removal of hydrogen sulfide from simulated biogas streams using sterically hindered amine adsorbents

Discovering the Interference of Hydrogen Sulfide on Polyethylenimine-Functionalized Porous Resin for Biogas Upgrading via CO2 Adsorption

“…Quantitatively, from 30 °C to 90 °C, the H 2 S adsorption capacities of 30% PEI/HP20 and 50% PEI/HP20 under the highest concentration of 5000 ppm were reduced from 0.91 to 0.02 mmol/g and from 1.14 to 0.02 mmol/g, respectively, and the corresponding attenuation ratios reached 97.8% and 98.2%. Compared with CO 2 , H 2 S adsorption of PEI/HP20 was more sensitive to the temperature, which was why amine-functionalized materials as H 2 S adsorbents in other studies were commonly operated at room temperature (≤30 °C). , The adsorption of H 2 S over PEI/HP20 was predominately determined by the thermodynamics instead of the kinetic effect. Even so, conventional amine-functionalized adsorbents did not seem suitable for H 2 S removal from biogas, because of the inconsiderable adsorption capacities, as shown in Table .…”

“…Similar spectra were also obtained under the atmospheres with lower H 2 S adsorption (5–500 ppm), as shown in Figure S4 in the Supporting Information, and the absorbance was expected to be reduced. Evidence of the H 2 S binding could be found in the prominent IR bands at the broad span of 2600–1900 cm –1 , which were associated with the S–H stretching vibration of the adsorption species . Specifically, some researchers considered that the complex stretching modes were attributed to the S–H···N hydrogen-bonded species and the formation of NH 2 + ···SH – group, because of the physisorbed and chemisorbed H 2 S. , Furthermore, the absorbance peaks that appeared at 1836 and 1744 cm –1 were assigned to the stretching and deformation vibrations of N–H + , respectively. , Correspondingly, the IR vibrations at 3442 and 3122 cm –1 assigned to the asymmetric and symmetrical N–H + stretching were also observed, which further demonstrated the chemical binding between H 2 S and amines .…”

“…After all, as a toxic and corrosive acid gas, the associated H 2 S in biogas (50–5000 ppm) is another component besides CO 2 that can be reacted with amine groups. , The main reactions between CO 2 or H 2 S and amine groups under dry conditions are described in the following equations (eqs –). , Even if the desulfurization pretreatment can be applied before biogas upgrading, the residual trace sulfur-containing compound may cause cumulative degradation effects on amine-based materials during the long-term operation. Previous studies deal mostly with H 2 S removal from biogas using amine-functionalized materials as H 2 S adsorbents based on the above reactions, instead of exploring the effect of H 2 S impurity on downstream biogas upgrading. Okonkow et al and Chanka et al synthesized the modified silica and microcrystalline cellulose with different amine types to selectively remove H 2 S from biogas, respectively. , Instead, amine-functionalized materials have more obvious advantages in CO 2 capture and separation, which have received extensive attention as the CO 2 adsorbents rather than H 2 S adsorbents. Nevertheless, the impact of trace H 2 S, regarded as an acid impurity in biogas, on CO 2 adsorption and stability is barely investigated and must be evaluated .…”

“…Okonkow et al and Chanka et al synthesized the modified silica and microcrystalline cellulose with different amine types to selectively remove H 2 S from biogas, respectively. 34,35 Instead, amine-functionalized materials have more obvious advantages in CO 2 capture and separation, which have received extensive attention as the CO 2 adsorbents rather than H 2 S adsorbents. Nevertheless, the impact of trace H 2 S, regarded as an acid impurity in biogas, on CO 2 adsorption and stability is barely investigated and must be evaluated.…”

Synthesis of ZnO-CuO and ZnO-Co3O4 Materials with Three-Dimensionally Ordered Macroporous Structure and Its H2S Removal Performance at Low-Temperature

“…Hydrogen sulfide (H 2 S) is a major impurity that originates from varieties of processes such as coke ovens, coal or natural gas manufacturing, and oil refining [1,2]. H 2 S impurity must be removed since it is highly hazardous to both the environment and industrial processes.…”