Removing H2S from CO2 Streams

Jan 05, 2024

Removing hydrogen sulfide(H2S) from carbon dioxide (CO2) streams is vital in biogas production, natural gas processing, and carbon capture and storage applications. H2S is a toxic and corrosive gas. Its removal from CO2 streams is necessary to conform to pipeline injection standards and purity limits for CO2 usage. Environmental and safety factors also play a role in the need for removal. Physical absorption, chemical absorption, membrane separation, amine separation, and biological consumption are all methods by which H2S can be removed from CO2 or biogas streams. While each method has pros and cons, physical absorption offers the most straightforward, robust, and lowest CapEx option while safely converting the H2S into stable elemental sulfur for disposal or use as fertilizer.

Depending on the source, CO2 waste streams may vary widely in their composition compared to traditional biogas sources. Waste CO2 from plastic or chemical manufacturing sources may have no oxygen or moisture present and may contain exotic compounds not found in waste digestion. These are also typically generated at very high pressure and temperature. CO2 streams generated from amine or membrane separation of biogas may also have a low relative humidity or oxygen content and high levels of H2S due to the concentration effect after separation but are typically found at lower pressures. All these factors must be considered when selecting a versatile and cost-effective H2S removal solution for your site’s needs.

FerroSorp® H2S removal media has a base of iron hydroxide, which is the purest and most effective form of iron for H2S reduction. Iron Hydroxide inherently contains more oxygen (O2) within the molecule, making it more effective on CO2 streams that do not have any O2. FerroSorp® works on wet or dry gas, which makes it effective for CO2 streams regardless of the source.

FerroSorp® does not bond with exotic VOC compounds that may be present in the gas, making it safe and non-hazardous for disposal or land application.

Treating H2S in CO2

  • Pros:
    • Versatile applications for purified CO2, turning waste CO2 into a revenue stream
    • Enhanced oil recovery, food-grade additives, and chemical production
    • If the CO2 stream is vented or routed through a flare, air can be injected to maximize the media’s H2S absorption capacity
  • Cons:
    • Higher operating pressures and temperatures may increase energy consumption
    • Higher H2S concentrations per SCFM after CO2 is concentrated out of biogas

Treating H2S in Biogas –

  • Pros:
    • Enhances biogas quality and energy content
    • Renewable energy applications like power generation and transportation fuel
    • Lower H2S concentrations, simplifying the removal process
  • Cons:
    • Presence of additional impurities in biogas may require extra treatment steps

The choice of treatment depends directly on industry and application requirements. CO2 streams offer diverse utilization possibilities.

FerroSorp® SK is the only media in the industry that is pre-conditioned with CO2 from the factory, so no initial heat-up is experienced when exposed to biogas or pure CO2 streams.

Interra Global has media in stock in multiple warehouses across the US, coupled with rapid deployment options for the highly versatile VAV bulk media vessels that are made in America compliant.

The Author | InterraGlobal

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