Impregnated Activated Carbon

Chemisorption on the Impregnant

Impregnated Activated Carbon is the SorbiTech specialty grade for contaminants base carbon cannot hold at low ppm and ppb concentrations. The impregnant (sulfur, potassium iodide, potassium hydroxide, or custom blend) reacts chemically with the target species on the carbon surface, forming a stable compound held irreversibly through the bed life.

SorbiTech starts with a 4 mm cylindrical pellet or 4 x 8 mesh granule of activated carbon (BET 900 to 1100 m2/g, hardness above 90 percent) and impregnates the pore network in a controlled process. Physical adsorption on the base carbon runs in parallel with targeted chemisorption on the impregnant.

Impregnations and Their Duties

• Elemental sulfur: mercury capture in natural gas and LNG, mercury sulphide (HgS) formation, outlet mercury below 10 ng per Nm3
• Potassium iodide: mercury polishing where higher capacity per unit volume is the deciding constraint
• Potassium hydroxide: hydrogen sulphide and mercaptan capture upstream of catalysts that would otherwise poison at parts per billion
• Custom blends (potassium permanganate, copper salts): specific duties where standard impregnations do not match the contaminant chemistry

Mercury Guard Bed Duty

Natural gas, LNG, and cold box pre treatment streams typically carry trace mercury at 1 to 100 micrograms per normal cubic metre. The downstream specification requires below 10 nanograms per normal cubic metre to protect cryogenic aluminium heat exchangers from liquid metal embrittlement. Sulfur impregnated beds deliver 3 to 5 years of service before mercury breakthrough.

The bed is single use. Spent carbon is recovered through the SorbiTech mercury recovery stream where the captured mercury is separated and the carbon residue is disposed under the local mercury waste regulation.

Bed Sizing and Breakthrough Detection

Mercury beds are sized by inlet mercury load and target outlet concentration. H2S and mercaptan beds are sized by sulphur load and regeneration cycle. Breakthrough is detected at outlet sensors (continuous mercury analyser for mercury, online sulphur analyser for sulphur). Trigger concentration is set well below the downstream specification so the operator can switch to standby bed and procure replacement charge.

Forms and Supply

Supplied as 4 mm pellets or 4 x 8 mesh granules in 25 kg drums or 500 kg big bags. Impregnant loading specified per duty and verified per lot against the dynamic capacity test. Single use supply, mercury recovery through SorbiTech contract. SorbiTech delivers impregnated activated carbon across the mercury removal application, the oil and gas sector, and the parent activated carbon family.