Let’s discuss the precautions for catalyst sulfiding. Our catalyst is Qilu Type 1

(1) When heating the catalyst, strictly control the bed temperature rise rate to ≤30°C/h. (2) When the temperature reaches 110–120°C and 200–210°C, maintain that temperature for about 6 hours to release the adsorbed water within the catalyst. During this stage, the drains from various drain pipes and separators are emptied. (3) Before vulcanization, the hydrogen content in the mixture should be around 10% (on a dry basis). (4) The amount of vulcanizing agent added should be controlled at around 0.5–1.0%. (5) During the vulcanization process, the temperature at the inlet of the converter should be maintained between 200–210°C to ensure proper vulcanization of the catalyst; the maximum temperature in the catalyst bed should be kept between 400–450°C. (6) When there is significant sulfur penetration, it indicates that the vulcanization of the catalyst is nearly complete. At this point, the temperature at the reactor inlet can be increased gradually at a rate of 10–15°C/h, up to 280–350°C. (7) The sulfidation process is complete when the hydrogen sulfide levels at the reactor inlet and outlet are equal. (8) The sulfiding agent and hydrogen gas are removed, and the bed temperature is reduced to around 220°C

If CS2 is used as the vulcanizing agent, the hydrogen content before vulcanization should be around 25% (on a dry basis) as determined by hydrogen analysis

1. High-temperature, low-sulfur desulfidation. 2. Inadequate process preparation led to intermittent vulcanization. 3. The temperature is changed too quickly. 4. The online vulcanization time is integrated with the process gas time to prevent excessive temperature rise due to the heat of reaction.