Dimethyl Disulfide (DMDS):
- DMDS has the highest sulfur content, which reduces the amount of product required for converting oxides to active metal sulfides.
- Thermally stable with low viscosity, DMDS is suitable for gas- or liquid-phase injection.
- It begins to decompose to H2S at low temperatures, so the risks of reducing the metal oxides prior to sulfiding are eliminated.
- DMDS decomposes in two steps, further minimizing the risk of temperature excursions during sulfiding.
- TBPS 454 is not classified as a flammable material and has a low toxicity rating.
- TBPS 454 has a diesel-like odor, a more friendly and common smell for refineries.
- TBPS 454 starts to convert to H2S at the lowest temperature compared to other sulfiding agents, lowering the risk of reduction of metals and potentially lessening the time of the sulfiding operation.
- The hydrocarbon byproduct during a sulfiding operation for TBPS 454 is isobutane, which does not have the potential to dilute hydrogen in the recycle gas during a sulfiding operation.
Dimethyl Sulfide (DMS)
Dimethyl Sulfide (DMS) is a presulfiding agent for steam cracking, the process that turns hydrocarbons into ethylene and propylene, which is used for olefin-based products. DMS is added to the feedstock to reduce coke and carbon monoxide formation during the high temperature thermal cracking of hydrocarbons in the tubular reactors. Below are the advantages:
- DMS directly and completely decomposes to H2S at 1470°F (although some trace CS2 may remain), suitable for furnace operating temperatures.
- DMS usually requires only one injection point in the charge gas as DMS will disperse fairly well throughout the furnace system.