Question: Method for determining the diene value of gasoline fractions
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Gasoline fractions contain a certain amount of dienes. Therefore, an method for determining the diene value in gasoline fractions is needed. Each company that produces ethylene cracking gasoline and its hydrogenated products surely has its own analysis methods; however, there are some aspects in our unit’s analysis methods that are not clear. For example, the standards specify that 5–20 grams of sample should be used for testing. When 5 grams of sample are used, the diene value is 27.6, while when 20 grams of sample are used, the diene value is 11.2. Hence, we need a method for determining the diene value in gasoline fractions, and we would appreciate it if you could help analyze the reasons behind this phenomenon. Contact information: fang_023.student@sina.com. Thank you very much; we hope to receive your assistance.
This post was last edited by xwtsq on 2010-6-7 23:29. The UOP 326 is generally used for determining the diene value. When 5 g of sample is used, the diene value is 27.6; however, if 20 g of sample is used, it’s likely that the reaction will not be complete, resulting in a diene value of only 11.2 The specified sample weight is 5–20 g; in practice, this implies that less sample should be used when the diene value is high and more sample when the diene value is low, with some element of experience involved. There is some literature available on other methods; I have two articles that I can send to you. I haven’t conducted this analysis; I’m just making guesses based on the principles of the method.
Hello, Haiyou. Based on the analysis above, the appropriate result is 27.6 when 5g is weighed; I will think about this further. Please send your data to my email for further study*. Additionally, I would like to know if there are any other methods for measuring the diene value of gasoline fractions, such as chromatography. My current question is to determine exactly how much diene is present in the C5 fraction; once a method or approach is developed, it can be used to analyze the diene content in other gasoline fractions. Thank you, everyone.
The diene value analysis method for hydrogenated gasoline currently used in our factory is one that we developed based on UOP 326. In the past, we always took 20g of samples for analysis; we never used 5g of samples, so we were not aware of such differences in analysis results. Therefore, I would like to ask those who currently use the UOP 326 analysis method to come and discuss this matter, as well as to share this analysis method with us. Contact: fang_023.student@sina.com. Thank you very much; I hope to get your help.
It has been sent to your email; please check it. I hope it will be helpful to you.
UOP’s method is extremely troublesome; it takes a whole day for analysis, and chromatography isn’t mature yet – it’s frustrating
This post was last edited by ask123456 on 2012-11-15 20:22. For UOP 326, generally 10 g of sample is used; 20 mL of maleic anhydride/toluene solution is added, and the mixture is refluxed at a gentle boil for 3 hours. After cooling, water is added and the mixture is refluxed for another 15 minutes. It is then cooled, extracted, and titrated using an automatic titrator. 1. It is essential to keep the interior dry within the first 3 hours after starting and during the reflux process; no moisture must enter. 2. Add water and then cool it down; be careful not to spill it during extraction. 3. Through our experimental investigations, it has been found that for some samples, extraction is not necessary before titration with an automatic titrator; after cooling, they can be placed directly in the titration cup for titration, thereby improving efficiency. Some samples must be extracted, and this is related to the properties of the sample components. The results we usually obtain are
I learned it, :(:(:(:(:(