flow line 107 a in either case it is important that there is liquid flowing over the catalyst during the sulfiding step the liquid which flows over the catalyst helps to heat up the catalyst to the desired sulfiding temperature and absorb the heat released by the sulfiding process in this way temperature excursions during sulfiding are avoided in this particular embodiment the column is not liquid filled but operated with a continuous vapor phase like a typical distillation column gas and liquid are flowing counter currently in the column the sulfiding agent and hydrogen are injected into the reboiler where the reaction takes place to generate h 2 s the flow rate of hydrogen and sulfiding agent are set such that a molar ratio h 2 s h 2 is between 1 25 and 1 5 is obtained following the reaction typically a ratio of 1 9 is preferred the hydrogen and h 2 s along with vaporized hydrocarbons passes upward through the catalyst bed where sulfiding takes place the vent gas is monitored to measure the h 2 s concentration once the h 2 s is measured at its full concentration based upon that being produced in the reboiler the temperature is the column is raised to 600 u00b0 f or higher as required this is achieved by increasing the reboiler duty and or raising the operating pressure once 600 u00b0 f is reached throughout the entire column the vent.