For a 300,000-ton methanol project, what is the typical control level for CO2 in the gas composition entering the methanol synthesis tower?

In the gas entering the tower: CO2: 6.5%～7%; in the recycled gas: CO2: 5%～6.5%. A high level of CO2 results in higher moisture content in the methanol produced

About 3.0% in the fresh gas.

It depends on what your raw materials are; generally, different raw materials result in different amounts of CO2. (The presence of CO2 can also be more beneficial for temperature control, thereby enhancing stability; CO2 can also appropriately suppress the occurrence of side reactions.)

It is ideal to keep the hydrogen-to-carbon ratio between 2.0 and 2.1; you can calculate it based on the actual conditions of your factory.

There has been a lot of debate regarding this issue. Many manufacturers set the level at 3%, referring to the gas entering the tower; in fact, 5-8% is considered optimal for the reaction process. If you have time, you can conduct several experiments when the system is stable, by testing different levels and determining which one results in the highest yield

I agree with TH373637’s view; if someone on the front line could keep the CO2 level within the range of 3% to 8%, it would be great to determine the optimal CO2 level as a result.

In the gas entering the tower: CO2: 5%～7%; in the recycle gas: CO2: 2%～5%

Please pay attention to the analysis; conduct a few additional analyses as well. The CO2 content in fresh gas is lower than that in recycled gas, while CO2 levels are highest in recycled gas

From the chemical equation for methanol synthesis, the amounts of CO and CO2 required for synthesizing methanol vary depending on the amount of H2 available. The H2O produced as a result of the CO2 reaction has a significant impact on the chemical equilibrium; different ratios of CO to CO2 result in substantial differences in their respective one-way conversion rates. This is mainly due to the different catalytic selectivities of the methanol catalyst for CO2 and CO. Generally, at low temperatures, methanol catalysts exhibit a higher selectivity for the reaction with CO2 compared to CO. Moreover, these catalysts require different ratios of CO2 to CO depending on the stage of their use. Furthermore, in terms of reaction heat, the heat released when methanol is produced from CO is higher than that when methanol is produced from CO2. Simulation calculations using the optimal gas composition confirm that the higher the ratio of carbon monoxide to carbon dioxide, the greater the methanol yield; excessive CO2 content affects the conversion rate of CO in the synthesis tower. Therefore, at the initial stage of catalyst use (220–250°C), CO2 can be kept at 6–8%, while it should be kept below 6% above 250°C.