Pre-sulfiding of gasoline hydrogenation catalysts
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Question: « During the pre-vulcanization of the catalyst, there is a phase of constant temperature. I would like to know whether the vulcanizing agent needs to be stopped during this constant-temperature period? ? Why
At a constant temperature, the vulcanizing agent should keep running; it’s just the temperature that needs to be controlled. Look up the operating procedures to find out more.
During catalyst sulfidation, the main factors to pay attention to are the reactor temperature and the hydrogen sulfide concentration in the recycle hydrogen. When the temperature is constant, sulfiding can be stopped once the concentration in the recycle hydrogen meets the required level; otherwise, sulfiding must continue.
Of course, it keeps going—because the oxidation-state catalyst has a reaction process—and an adsorption process for sulfiding agents
The isothermal stage of the catalyst sulfidation process is a critical phase for sulfur incorporation into the catalyst. The concentration of hydrogen sulfide in the recycle hydrogen must be maintained at a specific level, in accordance with the requirements of the operation plan; if this concentration drops, sulfur needs to be added or the amount of sulfur added increased, while if the concentration is too high, the amount of sulfur added should be reduced. Under normal circumstances, do not stop sulfur injection.
The sulfur injection rate is controlled based on temperature and the hydrogen concentration in the circulating hydrogen; generally, there is no need to stop the process. If the H2S concentration in the circulating hydrogen remains high, then the amount of sulfur injected can be reduced or even stopped
Do you know why a constant temperature is necessary? Why do different catalyst systems provided by various patent holders require different constant temperatures? The reason for maintaining a constant temperature is that at this temperature, the sulfidation reaction of the catalyst occurs most intensely; and when the reaction is intense, hydrogen sulfide is consumed. So, should it be added or not? Different catalyst systems have varying temperature points and numbers of sulfurization reactions, which is why the sulfurization curves differ from one another.
Generally, the process continues without interruption; during the constant-temperature phase, it is important to maintain an appropriate amount of sulfur injection to meet the requirements regarding hydrogen sulfide concentration at that temperature. As a result, the reactions occur relatively concentratedly at this temperature. It is necessary to adjust the sulfur injection amount promptly and to monitor the hydrogen sulfide concentration regularly. However, when the concentration becomes too high, sulfur injection can be temporarily stopped.
The injection of the vulcanizing agent must not be stopped; the constant-temperature phase in between is necessary so that hydrogen sulfide can penetrate through the catalyst bed, which helps to prevent the catalyst from being affected in the absence of hydrogen sulfide and high temperatures； Excessive reduction converts the catalyst to its elemental metallic state. Once reduced to its elemental metallic state, the catalyst can no longer be fully sulfided ； This can easily lead to a decrease in catalyst activity or complete loss of activity.