Despite its effectiveness, HDS faces several challenges:
Catalyst deactivation: Over time, the catalysts can lose their activity due to the deposition of carbon (coking) or the formation of metal sulfides. Refractory sulfur compounds: Some sulfur compounds, such as thiophenes and benzothiophenes, are more resistant to HDS and require more severe operating conditions or specialized catalysts for effective removal. Hydrogen consumption: HDS is a hydrogen-intensive process, and the availability and cost of hydrogen can be limiting factors.
