What is the principle behind the temperature rise in hydrogenation reactions?
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Is there anyone who could take the time to explain to me why there is a temperature rise during the feeding stage at the beginning of the hydrogenation reaction? What caused it
This post was last edited by shenjian*andao on 2019-5-17 10:24; there is a reason related to the heat of adsorption. In my opinion, there is another reason: in the initial stage, the catalyst surface contains active sites with high activity. However, these highly active sites are unstable; they accelerate the reaction as soon as the material is added, and their number then decreases.
Can it be understood as being caused by an imbalance between the adsorption heat and the reaction heat?
“At the beginning of the hydrogenation reaction, when feeding materials in, is it crude oil or sulfided oil that is used? Hydrorefining or hydrocracking?
When the unit is put into operation and the dry catalyst comes into contact with oil for the first time, there is generally an adsorption heat; if the catalyst is sulfided using a wet method, this heat will be evident when sulfurized oil is introduced into the unit, although the temperature rise seems to be modest. After the sulfidation process is completed and feed oil is introduced, the catalyst’s high initial activity generally causes an increase in bed temperature, with the extent of this temperature rise depending on the catalyst.
When the catalyst is initially wetted by the liquid phase, adsorption heat is generated
After drying, the catalyst becomes too dry, resulting in excessive adsorption capacity and thus heat release during adsorption. You can understand it that way
Heat release is normal. In the initial stage, the catalyst has high activity and the reaction is intense; consequently, more heat is released, and the temperature rise is naturally high. The amount of cold hydrogen can be increased appropriately to control the temperature rise.
The hydrogenation reaction is a highly exothermic reaction, and the heat released in this reaction is manifested as an increase in the temperature of the bed
Hydrogenation units experience temperature rises both during the initial catalyst presulfurization and during normal operation, as the hydrodesulfurization reaction is exothermic; controlling these temperature rises relies mainly on the use of cooling hydrogen.