The necessity of AA-grade methanol quality requirements in the United States
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I’ve heard that the best option is the one that’s most suitable, so I’d like to ask those who are more experienced: 1. Which downstream products of methanol require methanol of AA grade quality? 2. Which downstream products of methanol can be made using crude alcohol?
Yes, there’s no need to force the quality of methanol to meet the American AA standard. It is said that this standard sets strict requirements regarding the ethanol content; but actually, what’s the harm in having a small amount of ethanol in products such as methanol gasoline?
It’s mainly the ethanol content, but for most downstream products, the ethanol level is determined through negotiation between supply and demand parties. The AA grade standard in the United States requires that the ethanol content be below 10PPM; products such as acetic acid have such requirements!
Industrial methanol – United States Federal Standard (O-M-232G), “AA” grade. Parameter names and specifications: Ethanol ≤10 ppm; Propanol ≤10 ppm. Free acid content (as HAc) ≤30 ppm. Appearance: Colorless and transparent. No discoloration when tested with concentrated H2SO4. Color: Not darker than level 5 on the ASTM platinum-cobalt scale. Boiling range (at 760 mmHg): Within 1°C of 64.6±0.1°C. Specific gravity d ≤0.7928. Non-volatile substances ≤10 mg/100 mL. Odor: Characteristic of alcohols, with no other odors. Moisture content ≤0.1 wt%. In the potassium permanganate test, no discoloration occurs within 30 minutes
It seems that people are not very clear about which downstream products actually require AA-grade precision for methanol
The downstream methanol products required to meet AA-grade standards are mostly those for acetic acid production; there are specifications regarding the ethanol content in pure methanol. If the ethanol level is too high, propionic acid is formed, which affects the quality of the main product, acetic acid.