[Q&A Question 209] 2016.11.15
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【Q&A Question 209】November 15, 2016: Explain the principle of starting up a new catalyst using low-nitrogen oil. A reference ** will be shown after responding; scoring is achieved by answering the key points. Fresh catalysts or regenerated catalysts have very high reactivity due to their active centers remaining uncontaminated; moreover, it is difficult to determine the exact starting point for the reaction. In addition, when fresh catalysts come into contact with oil, an adsorption heat of around 5°C is generated ； Therefore, if the high-temperature oil feeding method using an old catalyst is employed, a violent reaction will occur when the oil comes into contact with the catalyst, and the reaction temperature cannot be controlled. For fresh catalysts, the required feed oil temperature is reduced from around 320°C for old catalysts to 150°C; on this basis, the temperature is increased gradually to keep the bed temperature within a controllable range. However, feeding oil at low temperatures provides favorable conditions for controlling the bed temperature, but it introduces another problem: at low temperatures, the refining catalyst fails to perform its refining function. It takes some time to raise the temperature from 150°C to the temperature at which the reaction begins; as a result, the extremely high amount of nitrogen present in the raw materials enters the reactor directly, causing permanent poisoning of the catalyst. Therefore, at low temperatures, the reactor cannot accept high-nitrogen oil; only low-nitrogen oil can be used. The quality specifications for low-nitrogen oil are: diesel with an ASTM distillation final boiling point of ≤330°C and a total nitrogen content of ≤100 ppm. 2016 Q&A Summary Post (updated as of November~~~~) http://bbs.hcbbs.com/thread-1597792-1-1.html Seeking sponsors for the “2016 Haichuan Top 10 Members Selection Contest” http://bbs.hcbbs.com/thread-1628108-1-1.html (Source: Haichuan Chemicals Forum)
It prevents the catalyst from overheating and forming carbon deposits; the new catalyst has a high level of activity, which facilitates temperature control. In the case of cracking catalysts, a high nitrogen content can deactivate the acidic centers involved in the cracking process!
When feeding oil, it is necessary to use low-nitrogen oil; otherwise, high nitrogen levels will lead to intense reactions and significant heat generation, which can cause the bed temperature to rise sharply, damage the catalyst, and result in safety accidents.
Hydrocracking catalysts have acid centers, while nitrogen-containing organic compounds in the feedstock are basic; these basic substances can neutralize the acid centers, resulting in catalyst deactivation.
Fresh catalysts or regenerated catalysts have very high reactivity due to their active centers remaining uncontaminated; moreover, it is difficult to determine the exact starting point for the reaction. In addition, when fresh catalysts come into contact with oil, an adsorption heat of around 5°C is generated； Therefore, if the high-temperature oil feeding method using an old catalyst is employed, a violent reaction will occur when the oil comes into contact with the catalyst, and the reaction temperature cannot be controlled. For fresh catalysts, the required feed oil temperature is reduced from around 320°C for old catalysts to 150°C; on this basis, the temperature is increased gradually to keep the bed temperature within a controllable range. However, feeding oil at low temperatures provides favorable conditions for controlling the bed temperature, but it introduces another problem: at low temperatures, the refining catalyst fails to perform its refining function. It takes some time to raise the temperature from 150°C to the temperature at which the reaction begins; as a result, the extremely high amount of nitrogen present in the raw materials enters the reactor directly, causing permanent poisoning of the catalyst. Therefore, at low temperatures, the reactor cannot accept high-nitrogen oil; only low-nitrogen oil can be used. The quality specifications for low-nitrogen oil are: diesel with an ASTM distillation final boiling point of ≤330°C and a total nitrogen content of ≤100 ppm.
The basic nitrides present in the feed oil form strong adsorption with the acidic sites of the catalyst; as a result, the new catalyst exhibits high activity, the reaction proceeds rapidly, and the large amount of heat generated leads to significant carbon deposition on the catalyst surface, causing a substantial loss of its activity.
Fresh catalysts or regenerated catalysts have very high reactivity due to their active sites remaining uncontaminated; it is also difficult to determine the exact starting point for the reaction. In addition, when fresh catalysts come into contact with oil, an adsorption heat of around 5°C is generated. Therefore, if the high-temperature oil feeding method using an old catalyst is employed, a violent reaction will occur when the oil comes into contact with the catalyst, and the reaction temperature cannot be controlled. For fresh catalysts, the feed oil temperature needs to be reduced from around 320°C for old catalysts to 150°C, after which the temperature should be increased gradually to keep the bed temperature within a controllable range.
Fresh catalysts or regenerated catalysts have very high reactivity due to their active centers remaining uncontaminated; moreover, it is difficult to determine the exact starting point for the reaction. In addition, when fresh catalysts come into contact with oil, an adsorption heat of around 5°C is generated； Therefore, if the high-temperature oil feeding method using an old catalyst is employed, a violent reaction will occur when the oil comes into contact with the catalyst, and the reaction temperature cannot be controlled. For fresh catalysts, the required feed oil temperature is reduced from around 320°C for old catalysts to 150°C; on this basis, the temperature is increased gradually to keep the bed temperature within a controllable range. However, feeding oil at low temperatures provides favorable conditions for controlling the bed temperature, but it introduces another problem: at low temperatures, the refining catalyst fails to perform its refining function. It takes some time to raise the temperature from 150°C to the temperature at which the reaction begins; as a result, the very high amount of nitrogen present in the feedstock enters the cracking reactor directly, causing permanent poisoning of the catalyst. Therefore, at low temperatures, the reactor cannot accept high-nitrogen oil; only low-nitrogen oil can be used. The quality specifications for low-nitrogen oil are: diesel with an ASTM distillation final boiling point of ≥330°C and a total nitrogen content of ≤100 ppm.
Fresh catalysts or regenerated catalysts have very high reactivity due to their active centers remaining uncontaminated; moreover, it is difficult to determine the exact starting point for the reaction. In addition, when fresh catalysts come into contact with oil, an adsorption heat of around 5°C is generated； Therefore, if the high-temperature oil feeding method using an old catalyst is employed, a violent reaction will occur when the oil comes into contact with the catalyst, and the reaction temperature cannot be controlled. For fresh catalysts, the required feed oil temperature is reduced from around 320°C for old catalysts to 150°C; on this basis, the temperature is increased gradually to keep the bed temperature within a controllable range. However, feeding oil at low temperatures provides favorable conditions for controlling the bed temperature, but it introduces another problem: at low temperatures, the refining catalyst fails to perform its refining function. It takes some time to raise the temperature from 150°C to the temperature at which the reaction begins; as a result, the extremely high amount of nitrogen present in the raw materials enters the reactor directly, causing permanent poisoning of the catalyst. Therefore, at low temperatures, the reactor cannot accept high-nitrogen oil; only low-nitrogen oil can be used. The quality specifications for low-nitrogen oil are: diesel with an ASTM distillation final boiling point of ≤330°C and a total nitrogen content of ≤100 ppm