Why must straight-run naphtha be used for presulfurization?
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May I ask the experts why straight-run naphtha must be used for presulfurization? Why can’t other types be used?
The preventive reaction heat is high; after pre-sulfurization, the catalyst also needs to be passivated in order to prevent excessive catalyst activity and coking
As pre-sulfidization proceeds, the catalyst gradually shifts from its oxidized state to its sulfided state; at this stage the catalyst has high activity. If recycled oil is used, it will exacerbate coking of the catalyst, and temperature control becomes difficult, leading to overheating
Control the bed temperature to prevent overheating!
It depends on what your equipment is used for in processing; for diesel production, straight-run diesel is generally chosen, while for kerosene hydrogenation, straight-run kerosene is used. Straight-run oil has good properties, a low nitrogen content, and it does not suppress catalyst activity nor cause intense reactions. Gentle operation, which is beneficial for the pre-vulcanization effect
A quick response here#: It mainly contains hydrocarbons with 4 to 12 carbon atoms, or heavier ones, as well as small amounts of sulfur compounds. This type of gasoline is composed primarily of saturated hydrocarbons with fewer unsaturated hydrocarbons, which gives it high chemical stability
Straight-run oil has a low olefin content and a low nitrogen content
Distilled oil has a low content of olefins, low gum content, and low sulfur content. Before adding a vulcanizing agent, the catalyst dust must be washed with distilled oil. The catalyst exhibits high activity in the initial stage of vulcanization; the use of reprocessed oil leads to a significant increase in temperature, which causes coking of the catalyst and reduces its service life； There are also those that use kerosene ； During pre-vulcanization, sulfur is injected without raising the temperature, and no sulfur is injected when the temperature is raised ；
1. Prevent excessive temperature rise during the sulfidation process. 2. Prevent impurities in low-quality raw materials from blocking the active centers and reducing their activity.