What is the source of amine substances in finished methanol?
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Our plant produces methanol using a natural gas one-stage converter + Ruichy methanol synthesis tower + three-column distillation process. 1. Currently, it has been detected that the content of trimethylamine in the methanol product is quite high; we would like to ask our colleagues in the methanol industry: where do these amines come from? Can a small amount of N2 react with H2 in a synthesis tower at a pressure of 8 MPa and a temperature of 240 degrees Celsius, in the presence of a copper-based catalyst? 2. How to reduce the content of these amines in methanol products? Can increasing the distillation temperature or adding more alkali help?
I’m sorry; my previous answer wasn’t relevant. What desulfurizing agent was used initially for desulfurizing natural gas? Nowadays, alcohol amine solutions are often used for this purpose in natural gas processing, and this may result in amines entering the system. . . We can analyze this aspect of Ha. This post was last edited by luobangyanyan on 2007-12-24 13:48.]
The original poster mentioned natural gas methanol, and it has nothing to do with coke oven gas. The natural gas used in the poster’s setup comes from somewhere; generally, ammonia is present in coal-derived gas, but it’s not clear whether ammonia is present in natural gas conversion products. This post was last edited by purpleghj on 2007-12-24 13:20]
Using natural gas as a raw material, it is possible that a small amount of nitrogen is introduced during the gas generation process. The locations where NH3 may be formed during the synthesis process are presumed to be: (1) there is Fe in the methanol catalyst; (2) Fe is present along the path taken by the synthesis gas stream containing a small amount of N2. In the past, in our laboratory experiments to produce syngas by reacting air with methane, when stainless steel reactors were used directly, NH3 was detected in the products after a considerable amount of time had passed.
Various methylamines may be the result of the reaction between NH3 and CH3OH
Upon careful consideration, adding a certain amount of ammonia to the boiler feed water in the drum might be carried into the conversion tubes along with the process steam. Another possible reason is that our plant uses ethanolamine to recover CO2, which is then compressed and added back to the system; as a result, some of that CO2 may be carried along as well. As for the synthesis pressure of only 8 Mpa at 235 degrees Celsius, the conditions required for ammonia synthesis are quite extreme; it’s unlikely that this is possible. Nevertheless, it’s still best to do the calculations :)
Based on the conditions you have provided, I personally think that: 1. Various methylamines are likely the result of a reaction between NH3 and CH3OH, and catalysts based on iron should be taken into consideration. 2. It is possible that the ammonia added to the boiler feed water in the drum, as you mentioned, could be carried into the conversion tube along with the process steam.