Why is the level of crude methanol methyl formate high?

Carbon monoxide reacts with methanol to produce methyl formate, whose structural formula is HC(O)OCH3. A colorless, fragrant, volatile liquid. Miscible with ethanol, soluble in methanol and ether. It is prone to hydrolysis, and the moisture in humid air can also cause it to hydrolyze. It has a strong irritating effect on the respiratory tract, eyes, and nose, and can cause a feeling of pressure in the chest as well as difficulty breathing.

Synthesis method 1. Direct esterification method: Obtained by the esterification of formic acid and methanol. Anhydrous calcium chloride and formic acid are mixed and stirred while cooling. Add methanol slowly. Reflux for 2.5 hours, and the product is obtained by distillation. As an alternative to using calcium chloride, formic acid and methanol can also be heated under reflux; the distillate with a relative density of 0.947 is collected via distillation to yield methyl formate, in a yield of 90%. Raw material consumption quota: formic acid 845 kg/t, methanol 600 kg/t. 2. The carbon dioxide method involves using a boron trifluoride solution in methanol, with an iridium complex as catalyst, and introducing carbon dioxide and hydrogen; the reaction takes place at 100°C and 5.88 MPa to produce methyl formate. 3. Methanol carbonylation method. 4. Methanol dehydrogenation method. 5. Methanol oxidation dehydrogenation method. 6. One-step synthesis method using syngas. Refining method: The impurities that are likely to be present are free formic acid and methanol. During purification, anhydrous potassium carbonate is added for drying followed by distillation, or phosphorus pentoxide is used for fractional distillation at 80–90°C in a water bath. It can also be washed first with a concentrated sodium carbonate aqueous solution, dried with solid sodium carbonate, and then subjected to fractional distillation with phosphorus pentoxide.

Too little or too much alkali may be the issue.

Can high levels of methyl formate occur if the pressure for methanol synthesis is too low?

The analysis of crude methanol showed a methyl formate content of 400 ppm; the cause is under investigation.

Both carbon dioxide and carbon monoxide can be produced from methanol and hydrogen through the process of methanol carbonylation. The main reasons for this are as follows: 1: Catalysts – the selectivity of catalysts is generally limited; it is primarily influenced by the catalysts themselves and the additives used. If these additives contain elements such as ruthenium, rhodium, palladium, or iridium of the electron-donating type, they will facilitate methanol carbonylation. It is recommended to increase the space velocity. 2: Excess methanol content in the gas entering the synthesis tower, damage to the demisting mechanism at the top of the methanol separator, or an excessively high inlet temperature for the methanol separator (above 45°C). It is suggested to add a full-alcohol washing column to the recycle gas stream, which can also improve the yield of methanol. 3: A low hydrogen-to-carbon ratio in the gas entering the synthesis tower; it is recommended to increase the space velocity and the recycle ratio. 4: Elevated or unstable temperatures; pressure has little impact. It is advised to control the outlet temperature of the synthesis tower based on the methanol yield

Analysis of the increased methyl formate content in crude methanol: 1) Changes in the selectivity of the catalyst, resulting in an increase in the amount of formic acid produced； 2) Due to the increased production of formic acid, this reacts with methanol to form methyl formate, resulting in an increase in its concentration; the level of methyl formate detected in crude methanol rose from 100 ppm to 400 ppm ； 3) Decreased catalyst activity leads to an increase in the amount of impurities generated ； 4) The reaction pressure decreases, resulting in an increase in the amount of impurities generated ； 5) Changes in the composition of the fresh gas, with an increase in carbon monoxide levels, leading to an increase in the amount of impurities generated ； 6) Influences of factors such as space velocity and methanol in the gas entering the tower.

What are the hazards of high levels of methyl formate for the product?