On the presulfurization and passivation of hydrogenation catalysts

In the case of dry vulcanization, the high-pressure sulfur injection pump may experience problems, leading to an interruption in sulfur injection.

1. The catalyst sulfidation reaction is an exothermic reaction; in case of an emergency, it may cause a spike in bed temperature. Therefore, the temperature limits specified in the pre-vulcanization step must be strictly followed, and the reactor bed temperature should be closely monitored. During pre-sulfidation, if the catalyst is reduced, it can be damaged. Reduction is a reaction in which metal oxides on a catalyst react to form pure metal, rather than a reaction that produces metal sulfides. At higher temperatures, if the hydrogen sulfide content in the circulating hydrogen is low, the reduction reaction occurs easily. Therefore, during pre-vulcanization, it is crucial to accurately control the vulcanization temperature and hydrogen sulfide concentration. 2. Precautions during vulcanization and passivation: (1) Four hours after adding the vulcanizing agent, measure the hydrogen sulfide concentration in the recycled hydrogen every half hour. (2) Four hours after ammonia passivation, the ammonia content in the highly acidic water was measured every half hour. (3) If the total temperature rise in the refined reactor bed exceeds 30°C, heating should be stopped, and the reactor inlet temperature should be maintained unchanged until the temperature rise falls below 30°C. (4) If the temperature rise of any bed in the cracking reactor exceeds 5°C, the heating of the cracking reactor is stopped. (5) During pre-vulcanization, due to the high hydrogen sulfide level in the reaction system, the hand valve on the pressure gauge at the high-pressure system site was closed. 3. Since emergency accidents during pre-vulcanization are unpredictable, handle them in accordance with the following procedures and the corresponding accident response plans outlined in the operating procedures for the hydrogenation unit. (1) Interruption of fresh hydrogen supply (2) Interruption of recycled hydrogen supply (3) Measures for dealing with temperature out-of-control during passivation (4) Failure of the sulfur injection pump (5) Failure of the ammonia injection pump (6) Over-temperature in the hydrogenation catalyst bed (7) Over-temperature in the cracking catalyst bed (8) Interruption of purge air supply (9) Interruption of gas supply (10) Power outage (11) Interruption of feed supply.

I’ve learned it! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !

The pre-sulfurization and passivation of hydrocracking catalysts are tasks that must be carried out before a hydrogenation unit is put into operation; as long as these steps are followed strictly according to the established plan, no major problems will arise.

During the sulfidation stage, the hydrogen sulfide content in the circulating hydrogen is too high; it’s not possible to use a hydrogen desulfurization unit, and there’s a risk that the circulating hydrogen compressor will be corroded. What’s the solution?