In batch distillation, if the temperature is high later on, will the impurities in the light component also increase?
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This post was last edited by d582114 on 2023-9-30 at 22:26. Regarding the issue of batch distillation: in batch distillation, does an increase in the temperature of the reactor lead to a decrease in the amount of light components? When the reactor temperature exceeds the temperature of the product, it only increases the impurities in the heavy components, not those in the light components. Is my understanding correct? In the graph, the peak at 9.5 minutes shows a downward trend, while the peak for the later stage is only 0.1; yet the impurity level in the final product at 9.5 minutes is 0.5. My supervisor said that I did too much back-distillation, but I don’t quite understand this. I admit that the post-distillation extraction has an impact, but it will only affect the main component, or the peaks that follow the main component. I’m not sure if my understanding is correct Please help me, everyone. This is from the post-distillation process and did not end up in the final product. Looking at the peak at 9.5 minutes, it’s only 0.1. This is the peak of the finished product from the control system; as for the one at 8.8 minutes, it’s 0.55. We consider values below 0.5 to be acceptable. I’d like to know if my understanding is correct If it is due to delayed posterior distillation, it should affect the main peak or the peak that follows the main peak; it should not affect the peaks before the main peak. All of these 5 graphs from the control system show a trend of decreasing values at 9.5 minutes. Gurus, is my understanding correct? Even if the temperature is high later on, the impurities formed are those with high boiling points, which come after the main components; it should not be the light-component impurities that appear first. Wouldn’t it be much better if more of the initial distillate was collected? Because we still need to recover it once in the final distillation. Collapse Chemicals 1 Followed ·0 Comments
In batch distillation, an increase in temperature later on may lead to a further rise in the impurity content of the light components, as these components generally have lower boiling points; as the temperature rises, they vaporize at higher levels and enter the top along with the steam. Furthermore, during operation, the distillation column may experience uneven heating and local blockages, which can also lead to an increase in the impurity content of the light components. .
Thank the original poster for sharing; I’ll participate and learn from it.
I’m not a professional in analysis. If the chromatography time indicates the boiling point of the distillate, then your understanding is likely correct. Under normal circumstances, higher temperatures result in fewer light components; however, in actual production, sometimes higher temperatures can lead to the formation of certain light-component impurities in some products
Yes, the one at 14 minutes is the peak; the one at 12 minutes is indeed a little higher, but aside from that, only the one at 9.5 minutes fails – the temperature dropped throughout. Since that indicator shows a downward trend in the control panel, it should be fine then
I’m not very familiar with analysis, and due to my limited knowledge I don’t fully understand the questions you’ve raised; therefore I’ll only share my personal opinion: The peak time in material chromatography seems to have little to do with the time at which you collect the fractions or with the amount of impurities present. The peaks corresponding to impurities don’t necessarily appear after those corresponding to the main component! This peak can only be attributed to a high level of impurities! It’s an uncertain answer; let’s discuss it together!
Generally speaking, the recombination value in later stages tends to be higher
……I think the original poster’s understanding is reasonable; light components are usually extracted in large quantities during the pre-extraction distillation process, so there shouldn’t be many light components left later on :)
Could it be that the internal convection is uneven, with some of the lighter components that hadn’t emerged earlier emerging at a certain point due to the higher temperatures later on?
It is necessary to confirm whether the light components in the initial fraction have been completely removed. In some cases, after collecting the initial fraction for a while, intermediate components start to appear, increasing the content of the product and thereby diluting the concentration of the initial fraction; this creates an illusion that the desired product has been obtained. In reality, however, there are still light components remaining in the bottom of the tower, which means that these light components are still present in the system later on.
Another possibility is that the temperature is too high, causing light components to be generated through decomposition in the tower bottom; I have encountered similar problems before