【Q&A Question 249】2018.09.12

High pressure places high demands on the equipment, and allowing it to persist for long periods is detrimental to the equipment； High pressure increases the energy consumption of the device, but it also raises the hydrogen partial pressure, which is beneficial for the reaction.

The control of reaction pressure depends on factors such as the equipment’s capacity, the required degree of hydrogenation, and the amount of hydrogen to be added. The effect of pressure on the reaction is achieved through hydrogen partial pressure. Increasing the hydrogen partial pressure of the system can accelerate the hydrogenation reaction, as well as the rates of desulfurization, denitration, and olefin saturation. Therefore, after increasing the pressure, the resulting product has a low bromine value, contains fewer sulfur and nitrogen compounds, and exhibits good oil stability. At the same time, increased pressure can also suppress coking in the bed, which helps maintain catalyst activity and improves its stability. The adjustment of reaction pressure must be based on the guarantee of product quality; reaction pressure can be increased by increasing the amount of fresh hydrogen, reducing the reaction temperature, or decreasing the space velocity.  Hydrogen partial pressure = Reactor inlet pressure × (Number of hydrogen molecules in the recycle gas + Number of hydrogen molecules added) / (Number of hydrogen molecules in the recycle gas + Number of hydrogen molecules added + Number of molecules vaporized from the feed)

This post was last edited by hesonchang214 on 2018-9-12 09:28. Reaction pressure, or more precisely, the hydrogen partial pressure, has a significant impact on the reaction. Since hydrogenation is a reaction that involves the reduction of molecules, increasing the reaction pressure is beneficial for hydrogenation; it helps to remove sulfur, nitrogen, oxygen, and metal compounds more effectively, saturates light hydrocarbons and aromatics, reduces catalyst carbon deposition, and extends the catalyst’s lifespan. However, increasing the pressure is limited by equipment constraints and results in higher investment costs

The higher the pressure, the less safe it is! There are extra costs for things like equipment selection. Impact on process operation: The hydrogenation reaction is a hydrogen-consuming reaction; the higher the pressure (hydrogen partial pressure), the more favorable it is for the reaction and for achieving greater reaction depth. An increased hydrogen partial pressure can inhibit coking reactions, promote hydrogenation saturation reactions, and reduce the catalyst deactivation rate. Temperature is generally the main control method, but when the temperature is already high enough for nitrogen removal, the reaction pressure can be increased appropriately.

The reaction pressure is reflected in the hydrogen partial pressure; a higher pressure helps to increase the hydrogen partial pressure and thus facilitates the progress of the hydrogenation reaction, whereas a lower pressure is unfavorable for it. However, the reaction pressure is limited by the design pressure of the equipment and pipelines, and under normal circumstances the reaction is not adjusted.

May I ask how to calculate the number of molecules you mentioned? Thank you

Answer: Reaction pressure, or more precisely, the hydrogen partial pressure, has a significant impact on the reaction. Since hydrogenation is a reaction that involves the reduction of molecules, increasing the reaction pressure is beneficial for hydrogenation; it helps to remove sulfur, nitrogen, halogens, and metal compounds more effectively, as well as to saturate light hydrocarbons and aromatics. This reduces catalyst carbon deposition and extends the catalyst’s lifespan. However, increasing the pressure is limited by factors such as equipment constraints.

Reaction pressure, or more precisely, the hydrogen partial pressure, has a significant impact on the reaction. Since hydrogenation is a reaction that involves the reduction of molecules, an increase in pressure is beneficial for hydrogenation; it helps to remove sulfur, nitrogen, oxygen, and metal compounds more effectively, and it also saturates olefins and aromatics, reducing catalyst fouling and extending the catalyst’s lifespan. However, increasing pressure is limited by the capabilities of the equipment. If the reaction pressure is reduced, the effectiveness of removing impurities such as sulfur, nitrogen, and oxygen decreases, the saturation rate of olefins and aromatics drops, which leads to catalyst fouling and shortens the catalyst’s lifespan.

Increasing the hydrogen partial pressure of the system can accelerate the hydrogenation reaction, as well as the rates of desulfurization, denitration, and olefin saturation. Therefore, after increasing the pressure, the resulting product has a low bromine value, contains fewer sulfur and nitrogen compounds, and exhibits good oil stability. At the same time, increased pressure can also suppress coking in the bed, which helps maintain catalyst activity and improves its stability. The adjustment of reaction pressure must be based on the guarantee of product quality; reaction pressure can be increased by increasing the amount of fresh hydrogen, reducing the reaction temperature, or decreasing the space velocity.

Reaction pressure, or more precisely, the hydrogen partial pressure, has a significant impact on the reaction. Since hydrogenation is a reaction that involves the reduction of molecules, an increase in pressure is beneficial for hydrogenation; it helps to remove sulfur, nitrogen, oxygen, and metal compounds more effectively, and it also saturates olefins and aromatics, reducing catalyst fouling and extending the catalyst’s lifespan. However, increasing pressure is limited by the capabilities of the equipment. If the reaction pressure is reduced, the effectiveness of removing impurities such as sulfur, nitrogen, and oxygen decreases, the saturation rate of olefins and aromatics drops, which leads to catalyst fouling and shortens the catalyst’s lifespan.