1. Selection according to target pollutants
Iron oxide desulphurisation agent
Main application: Highly efficient in removing hydrogen sulphide (H₂S), especially suitable for scenarios dominated by inorganic sulphur (e.g. natural gas, biogas, coal gas, etc.).
Limitations: Limited effectiveness in removing organic sulphur (e.g. mercaptans, mercaptans), need to be combined with other processes.
Wide applicability: can simultaneously adsorb H₂S, organic sulfur (e.g., mercaptans, thioethers), VOCs, odours, etc., suitable for complex mixed pollutant scenarios.
Modified activated carbon: the adsorption capacity of H₂S and organic sulfur can be enhanced by loading metal oxides or alkaline substances (e.g. KOH).
2. Selection according to operating conditions
Temperature and humidity
Iron oxide desulphurizer: requires a certain humidity (usually requires the gas to contain 10%~30% water vapour) to catalyse the reaction; wide range of applicable temperature (room temperature~60°C).
Activated carbon: best adsorption effect at room temperature, high temperature (>50℃) will reduce the adsorption capacity; some modified activated carbon can withstand higher temperature.
Sulfur concentration and gas composition
High concentration of H₂S (>1000 ppm): preferred iron oxide desulphuriser (high reaction capacity, high resistance to sulphur impact).
Low concentrations of mixed pollutants (containing H₂S, organic sulphur): activated carbon is more cost-effective.
Oxygen-containing gases: activated carbon requires safety attention (risk of spontaneous combustion), iron oxide desulphurisers do not.
3. Economy and maintenance costs
Initial cost
Iron oxide desulphurisers are usually less expensive, activated carbon (especially modified varieties) is more expensive.
Lifespan and regeneration
Iron oxide desulphurising agent: non-regenerable, need to be replaced when sulphur capacity is saturated (life time about 1~3 years, depending on sulphur concentration).
Activated carbon: can be regenerated at high temperature or chemically regenerated (regeneration 3~5 times), and the cost may be lower for long-term use.
Operating Energy Consumption
Iron oxide desulphurisation agent does not require additional energy consumption (relies on natural oxidation reaction); activated carbon regeneration requires high temperature or steam, which consumes more energy.
4. Safety and ease of operation
Iron oxide desulphuriser
Exothermic reaction, need to pay attention to the control of temperature rise in the high concentration of H₂S scenario (to avoid overheating of the bed).
No risk of spontaneous combustion, suitable for oxygenated or oxygen-free environments.
Activated Carbon
Exothermic by adsorption, high concentrations of H₂S may lead to localised high temperatures which need to be monitored; possible spontaneous combustion in oxygenated environments, inert gas protection required.
Chalking issues need to be considered (periodic sieving or selection of high strength carbon).
5. Typical Application Scenario Recommendations
Preferred scenarios for iron oxide desulphurisation
Biogas desulphurisation (high H₂S concentration and sufficient humidity).
Gas purification of natural gas, coal chemical industry and other gases dominated by inorganic sulphur.
Scenarios that do not require much organic sulfur and need a low-cost solution.
Preferred scenarios for activated carbon
Purification of complex gases containing organic sulphur such as coke oven gas and petroleum refinery gas.
Exhaust gas treatment that requires simultaneous removal of H₂S, VOCs and odour.
Scenarios with low sulphur concentration, intermittent operation or regeneration.
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