Selective separation of NH3 and CO2 in a mixed gas of NH3 and CO2
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For a mixed gas containing NH3 and CO2 in a molar ratio of 2:1, what methods are available to selectively separate NH3 from CO2? Please discuss it! This post was last edited by Pastoral Poet on 2009-4-28 10:05.]
Can the membrane method be used? Friends who have a good understanding of membrane separation technology, please discuss its possibilities.
I remember there was an expert in Taiwan who specialized in melamine; his patent described a method for separating NH3 and CO2 to obtain ammonia of relatively high purity.
Could an expert on melamine in Taiwan explain in detail whether, in his patents, there are methods for separating NH3 and CO2 to obtain ammonia of relatively high purity? This post was last edited by lxq700918 on 2009-4-2 20:39.]
The company was interested in melamine and gathered some information; from what he said at that time, the technology wasn’t yet very mature. NH3 and CO2 are in the post-system for producing melamine; to meet the needs of plants that only require pure ammonia to be recovered, distillation should be employed. Because the company was just a preliminary idea, and my understanding of it wasn’t in-depth; at that time the discussions took place in Chengdu.
That is the mature ammonia-carbon separation technology; what I am looking for is the selective separation of NH3 and CO2 from a mixed gas of NH3 and CO2. It is best to use the mother liquor from alkali production to partially absorb NH3 and CO2 in the mixed gas, thereby controlling the carbonation reaction. This post was last edited by lxq700918 on 2009-4-2 20:41.]
Use the mother liquor from soda production to partially absorb NH3 and CO2 from the mixed gas in order to control the carbonation reaction; I was wondering if there are any established methods for this in China
I heard that East China University of Science and Technology has conducted experimental research; could someone from that university please provide more details on this? This post was last edited by lxq700918 on 2009-4-21 at 13:01
Ammonia can be separated by introducing ammonia and CO2 into dilute ammonia solution
Selective ammonia and CO2 ammonia separation is of great significance!
Can ammonia be obtained from the top of a distillation tower using the ammonia vaporization method?
Using the ammonia vapor method won’t work, buddy
Ammonia water contains only ammonia, and it is feasible to recover ammonia by the ammonia evaporation method. However, if it also contains carbon dioxide, then it’s not possible!
This process can indeed be separated using a special membrane, but what is the use of separating ammonia from carbon dioxide in fertilizer plants?
After separation, ammonia and carbon dioxide can be used as raw materials for producing urea, or they can be sold directly as products (liquid ammonia, liquid carbon dioxide).
Separation using MDEA. First absorb CO2, and then analyze it.
This post was last edited by lxq700918 on 2009-5-19 13:13. This method is not feasible! There is water in the MDEA solution; during the absorption of CO2, ammonia reacts with this water to form ammonium hydroxide, which then enters the MDEA solution along with CO2. Therefore, it cannot be separated using this method.
Now, a ammonia-urea project is being carried out, which includes this part. It seems feasible; after urea is produced, it is necessary to remove both ammonia and CO2 from the urea solution. And this ammonia and CO2 return to the syngas used for urea synthesis. An Ammonia Carbamate Solution is used in this process. Isn’t this MDEA? (I’m not sure; I just derived it from the analysis project table.) Additionally, could the use of slaked lime to separate ammonia and CO2 be considered?
Ammonium carbamate: NH2-COONH4. Carboxyammonia: NH2-COOH. In an aqueous solution of ammonia and carbon dioxide, there are approximately 11 different ions and compounds; a significant portion of the ammonia exists in the form of carbamate ions, especially when the concentration of ammonia is high.
It can be absorbed in an absorption tower using dilute ammonia water. The lower part of the tower is the bubbling section, while the upper part is the distillation section; the temperature at the top is controlled, and the gaseous phase at the tower top is condensed to produce liquid ammonia. The dilute ammonia water at the bottom of the tower is recycled; once it reaches a certain concentration, it is sent for the production of urea or carbamide. (I’m not sure if it’s possible :) )
During the absorption process in the absorber, gaseous ammonia is absorbed, and at the same time, some CO2 is also absorbed. Therefore, without any special design considerations, the vapor phase at the top of the tower does not contain pure ammonia; instead, it remains a mixture of ammonia and CO2. However, if the proportion of CO2 in the mixture is not very high (at least not exceeding that of ammonia), it can be washed and absorbed properly, resulting in pure ammonia at the top of the tower. However, this method is not advisable.