The issue of hydrogen sulfide content in coal tar hydrogenation?
Thread Content
During the hydrogenation of coal tar, a certain level of hydrogen sulfide content must be maintained. What range should the hydrogen sulfide content in the circulating hydrogen be kept within during normal production, and what should it be during startup and shutdown? Why?
In typical recycled hydrogen, the hydrogen content ranges from 71% to 92%, with the remainder consisting of hydrogen sulfide, methane, and other compounds. Maintaining a certain level of hydrogen sulfide ensures that the catalyst remains in a sulfided state, thereby preserving its activity and selectivity
The hydrogen sulfide content in the circulating hydrogen should be determined based on the requirements of the catalyst. Generally, it is 1000ppm–2000ppm; high hydrogen sulfide levels inhibit desulfurization, while low levels cause the catalyst to be reduced.
It’s explained in great detail; basically that’s it
>300ppm. If it is too low, after water is injected at the inlet of the high-pressure air cooler, ammonia cannot be completely removed; this not only leads to the precipitation of ammonium salts in the pipelines following air cooling but also, as these substances are recycled back to the reactor, it harms the activity of the catalyst. Therefore, sulfur must be added to ensure no ammonia remains after washing.
In the formation mechanism of sulfided catalysts, hydrogen sulfide is required to keep the catalyst in an active sulfided state.
Why can ammonia not be completely removed when hydrogen sulfide is too low?
The hydrogenation process for coal tar operates on the same principle as that for diesel. I recommend that the H2S content in the recycled hydrogen be kept at no less than 100 ppm, as this will prevent catalyst deactivation