【Q&A Question 136】2017.05.16
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This post was last edited by 955559 on 2017-7-21 22:54. [Q&A Question 136] 2017.05.16: Why is straight-run oil chosen to ensure stable initial catalyst activity after the catalyst pre-sulfidization is completed? The reference answers will be visible after responding; points are awarded by identifying the key points. (Unless otherwise specified, all questions and answers are based on hydrogenation units.) ) ① At the end of catalyst pre-sulfidization, the initial activity and acidity are at their strongest ； ②If it comes into contact with low-quality raw materials, especially recycled distillate oils such as catalytic diesel and coker diesel at this time, intense hydrogenation reactions will occur, and cracking reactions may even take place, which can easily lead to overheating ； ③Furthermore, the carbon deposition on the catalyst surface occurs at a particularly rapid rate, causing the catalyst to become deactivated quickly and affecting its normal activity level during the stable period of activity. Therefore, straight-run oil should be selected. Scoring criteria: 2 Wealth points for incorrect attempts; 3–8 points for *incomplete* answers. 10 Wealth points for correct answers, provided with a detailed explanation; 15–20 Wealth points if the answer is correct but lacks sufficient details. Please score according to these criteria. Note: If there are editing records after answering, only those who participated will be credited points. For continuous malicious spamming, 2 points will be deducted each time, with no upper limit. Pure numbers, pure emojis, or random letters that have nothing to do with the answer are all considered malicious spamming; points will start to be deducted after three warnings. 2017 Q&A Summary Thread (updates have started) http://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates have started) http://bbs.hcbbs.com/thread-1657794-1-1.html 2016 Q&A Summary Thread (updates completed) http://bbs.hcbbs.com/thread-1597792-1-1.html
After the pre-sulfurization of the catalyst is completed, its reaction activity is extremely high. Since straight-run oil contains low levels of olefins, its low reaction activity makes the reaction easier to control.
1. When catalyst presulfidization is completed, its initial activity and acidity are at their strongest； 2. If it comes into contact with low-quality raw materials, especially secondarily processed distillate oils such as catalytic diesel and coker diesel at this time, intense hydrogenation reactions will occur, and cracking reactions may even take place, which can easily lead to overheating ； 3. The rate of carbon deposition on the catalyst surface is particularly high, causing the catalyst to become deactivated rapidly and affecting its normal activity level during the stable period of activity.
1. When catalyst pre-sulfidization is completed, its initial activity and acidity are at their highest. 2. If it comes into contact with low-quality feedstocks, particularly refined distillate oils such as catalytic diesel or coker diesel at this stage, intense hydrogenation and cracking reactions will occur, which can lead to overheating. 3. Carbon deposition on the catalyst’s surface accelerates, causing the catalyst to become inactive rapidly and affecting its normal activity during the stable period. Therefore, straight-run oil should be selected
Because the catalyst is too active, it is necessary to prevent the reaction from proceeding too quickly and causing excessive temperature rise; this also helps to avoid catalyst coking
1. It has the strongest acidity and activity in the initial stage； 2. Using other inferior oils can easily lead to hydrogen embrittlement ； 3. Catalyst carbon deposition accelerates, leading to easy deactivation
To avoid excessive temperature rise and rapid deactivation during the initial activation phase of the catalyst, it is usually necessary to first have high-quality straight-run distillate oil come into contact with the catalyst, allowing the catalyst to coking and deactivate gradually until its activity stabilizes. This process is known as the stabilization of the catalyst’s initial activation, or what is commonly referred to as passivation
(1) At the end of catalyst presulfidization, the initial activity and acidic functionality are at their strongest； (2) If it comes into contact with low-quality raw materials, especially secondary processed distillate oils such as catalytic diesel and coker diesel at this time, intense hydrogenation reactions will occur, and cracking reactions may even take place, which can easily lead to overheating ； (3) Additionally, the carbon deposition on the catalyst surface occurs at a particularly fast rate, causing the catalyst to become deactivated rapidly and affecting its normal activity level during the stable period of activity. Therefore, straight-run oil should be selected.