What is the typical hydrogen sulfide content in the liquid separation tank at the inlet of the cyclohydrogen compressor?
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What is the typical hydrogen sulfide content in the liquid separation tank at the inlet of the cyclohydrogen compressor?
Not less than 0.25 and not more than 0.5
Consider the impact on the catalyst based on one’s own process requirements； Generally, a hydrogen content of up to 50PPM in gasoline and up to 200PPM in diesel is no problem ； Excess hydrogen sulfide can affect the depth of the reaction; it’s best to consider all factors together.
Depending on the different process conditions, the concentration of hydrogen sulfide varies. For our equipment, the load varies, and so do the requirements for hydrogen sulfide concentration.
The processes are different, so the values vary
Studies have shown that when the volume fraction of hydrogen sulfide in the gas phase is above 0.3%, the sulfided structure of the catalyst can be well maintained. For the hydrogenation process using non-precious metal sulfide catalysts, a certain concentration of hydrogen sulfide must be maintained in the system; whereas in the hydrodearomatization process with catalysts based on active precious metals in their reduced state, hydrogen sulfide should be removed as much as possible. This is because only at a certain concentration of hydrogen sulfide do the active metal components of sulfide catalysts remain in their sulfide form and not get reduced by hydrogen.
For non-precious metal sulfided catalysts, it is necessary to maintain a certain hydrogen sulfide partial pressure in order to prevent a decline in activity due to the loss of sulfur from the catalyst； On the other hand, the adverse effects of hydrogen sulfide are: 1) it inhibits desulfurization activity, 2) it forms (NH4)HS with NH3 during the reaction process, thereby blocking the system, and 3) when its concentration is high, it can cause corrosion to the equipment. Therefore, in hydrogenation catalytic reaction systems using non-precious metal catalysts, the hydrogen sulfide concentration is typically required to be maintained at 0.03%–0.05%.
From the perspective of raw materials, if the sulfur content in them is above 3000 ppm, a hydrogen sulfide desulfurization unit is required; if it is below 500 ppm, a sulfurizing agent must be continuously added to ensure that the hydrogen sulfide level in the circulating hydrogen remains at least 50 ppm, otherwise there is a risk of the catalyst being reduced! From the perspective of the hydrocracking reaction mechanism, desulfurization is a reversible reaction; excessively high hydrogen sulfide concentrations inhibit the desulfurization reaction, but the presence of hydrogen sulfide promotes the denitration reaction. Generally, it is appropriate to maintain the hydrogen sulfide concentration in circulating hydrogen at 1000–2000 ppm