Methanol purification and quality improvement

Which aspect is the poster referring to? Do you need it at reagent grade?

Including those for reagents, as well as those for acetic acid, and so on

Industrial methanol can achieve 5 nines in terms of purity; I’m not sure how many nines you need? Pure reagent and industrial-grade reagent are two different concepts; for acetic acid, industrial grade level 1 is sufficient, as higher grades are not necessary. 99.85%, you can’t even explain what you’re trying to do

First, we need to understand what the factors affecting distillation operations are Apart from equipment issues, the factors affecting the distillation process include the following: (1) the temperature and pressure of the tower (including the top, bottom of the tower, and certain trays of special significance) ； (2) Feed condition ； (3) Feed rate ； (4) Feed components ； (5) Feed temperature ； (6) Vapor rise velocity in the tower and heating capacity of the evaporation kettle ； (7) Backflow volume ； (8) Top condenser cooling capacity ； (9) Top of tower yield ； (10) Bottom draw rate. The operation of the tower involves adjusting these influencing factors in accordance with the composition requirements of the products at the top and bottom of the tower. Furthermore, during the operation of extractive distillation and azeotropic distillation, changes in the addition temperature, purity, and amount of the extractant or azeotrope are also factors that affect the process. By clarifying these points, I think the quality of methanol can meet the requirements.

Three processes for methanol purification (two-column, high-quality three-column distillation, and energy-saving three-column distillation). Two-column process: The ethanol content in purified methanol depends on the ethanol content in crude methanol; whereas the ethanol content in crude methanol is influenced by synthesis conditions such as pressure, temperature, the stage of catalyst use, the composition of the syngas, and the structure of the raw materials. Crude methanol produced by the low-pressure process (including the high-pressure process using copper-based catalysts with light oil as a raw material) contains 100–1000 ppm of ethanol, whereas crude methanol obtained by the medium-pressure process (Biomethanol Process) and the high-pressure process (also using copper catalysts) with coal as a raw material can have ethanol levels as high as 400–2000 ppm. Therefore, the ethanol content in pure methanol also varies significantly, generally ranging from 100 to 600 ppm, and sometimes it can reach up to 1000 ppm. This is because in a double-column distillation system, the bottom of the main distillation column where the product is collected is almost entirely water. Moreover, the volatility of ethanol is relatively similar to that of methanol; as a result, ethanol cannot be concentrated in the bottom of the column. Therefore, some of the ethanol rises to the top of the column along with methanol, and a considerable amount of ethanol from the crude methanol ends up in the pure methanol. Based on domestic methanol production experience, the ethanol content in purified methanol can also be reduced by using a double-column atmospheric distillation method