Environmental Applications of Spent Hydroprocessing Catalysts

Spent-decoked catalysts pose an adequate activity in various waste gas and wastewater treatment applications. This involves selective catalytic reduction NO x and SO x , as well as the conversion of H 2 S to hydrogen and elemental sulfur. A high affinity of transition metals present in spent catalysts (e.g., Ni, Co, Mo, W, Fe, V) indicates the potential for utilizing these solids as hot gas clean-up sorbents for the removal of H 2 S, COS, mercaptans, and other sulfur-containing compounds from various gaseous by-products. Trace metals (e.g., Hg, Cd, and Pb) emitted from industrial operations in gaseous streams can be trapped in guard reactors filled with spent decoked-sulfided catalysts. The removal of contaminants from various wastewater streams is another area where spent hydroprocessing catalysts can be utilized.