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DMSO Enviro-S® Grade Product Sheet


Many organosulfur compounds are available for pretreating catalysts. The choice of a presulfiding agent should be guided by these factors:

  • Operational and environmental safety
  • Maximum sulfiding capability
  • Cost effectiveness


DMSO enviro-S

Preference for DMSO Enviro-S® Grade is due in large part to its low toxicity and odor. DMSO is easier and safer for plant personnel to handle than many other sulfur compounds. No toxicity problems have been encountered with DMSO Enviro-S® Grade since it became available in the late 1960’s. Risks to workers are minimal. If a leak or spill occurs, DMSO Enviro-S® may be diluted and flushed to the wastewater treatment facility where it is fully biodegradable by typical activated sludge bacteria.

DMSO is a fully saturated, low-molecular weight, sulfur-containing compound that begins to decompose at its boiling point of 372ºF. The presence of oxygen in DMSO appears to have no adverse effect on catalyst activity and is insignificant compared to that released from the catalyst. Water that may be present to control the freezing point would be in the vapor phase.

Inhalation Toxicity of Presulfiding Agents in Common Use (LC 50 for Rats )

DMSO Enviro-S® None at levels tested
Ethyl mercaptan 4,420 ppm
Butyl Mercaptan 4,020 ppm
Dimethyl disulfide 805 ppm
Methyl mercaptan 675 ppm
Hydrogen sulfide 444 ppm

Representative Specification

Specification Values
Assay, % Min. by GLC 99.7
Water, % Max. by KF 0.15
Titrable Acid, meq/g Max. 0.001

DMSO Enviro-S ® at a Glance

Physical Parameter Value
Molecular weight 78.13
Percent sulfur (mass %) 41.0 %
Boiling point 189 °C
Freezing point 18.45°C
Density (20°C) 1.099 g/cc
Heat of vaporization H v (70°C) 11.3 kcal/mol
Dielectric constant (20°C) 48.9
Flash point, open cup 95°C
Autoignition temperature 300-302°C

Catalysts Decomposition Temperatures Hydrotreating Catalysts in Hydrogen Atmosphere

Sulfur Agent Nickel-molybdenum Cobalt-molybdenum
DMSO Enviro-S® 420°F (216°C) 457°F (236°C)

Note: The temperatures shown above have been observed in hydrotreaters in the field to release sulfur for the generation of H 2 S. The catalyst determines the decomposition temperature for the spiking agent.


Soluble in water, light alcohols and diethyl either.


CAS: 67-68-5

EINECS: 200-664-3

HMIS and NFPA Hazard Ratings:  Health – 1, Flammability – 1, Chemical Reactivity – 0


Bulk : ISO Container and Tank Truck

The information in this bulletin is based on information available to us and on our observations and experiences. However, no warranty is expressed or implied regarding the accuracy of this data, the results to be obtained from the use thereof, or that any use will not infringe any patent. Each user must establish appropriate procedures for off-loading, handling, and use of the product(s). Since conditions for use are beyond our control, we will make no guarantee of results, and assume no liability for damages incurred by off-loading, handling, or use of the product(s). Nothing herein constitutes permission, or recommendation to practice any invention covered by any patent without license from the owner of the patent.

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