Hmm, this doesn't seem like a gold or PM recovery or refining thing.
As far as I know, hydrodesulfurization is a petrochemical refining process. This uses catalysts and hydrogen under pressure and heat to remove sulfur from petroleum refinery products like diesel fuel and natural gas (and maybe other petrochemicals). The hydrogen ultimately combines with sulfur to produce hydrogen sulfide, which is then decomposed into elemental sulfur. The more common name for this equipment is a hydrotreater.
The catalysts are nickel or cobalt and molybdenum, so there isn't even a precious metals linkage there.
The biggest usage of this that I am aware of is diesel deep desulfurization - making low sulfur diesel so that it doesn't produce so much SO2 pollution. Governments make diesel fuel specifications tighter every year, although I am still exposed to a huge number of stinky diesels where I live (BC interior).
Ah, the memories this brings back of touring the refineries on Refinery Row in Edmonton, and the heavy oil upgraders in Ft. McMurray and Llloydminster...and the mountains of elemental sulfur...
If you want tips on running a hydrotreater, you might consult books like Meyers' "Handbook of Petroleum Refining Processes." There are also some nice folks at the U of Alberta Pet Engg department that spend a lot of time working on hydrotreating and related heavy oil refining processes.
