Organosulfur chemicals are the preferred reagents for catalyst sulfidation. These compounds improve initial catalyst activity and lengthen production cycles for NiMo, CoMo, NiW, and CoW hydrotreating catalysts. Proper presulfiding allows unit operation at lower temperatures and extends catalyst cycles. Improved catalyst activity can be exploited to increase capacity or to enhance product quality. Organosulfur chemicals may also be used to moderate catalyst activity via low-concentration introduction into the unit's feedstock. This allows for the moderation of initial high catalyst activity and deactivation caused by coking. Please see our general sulfiding conditions page for more information on this process.