Requirements for crude methanol purification
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The quality of pure methanol produced by the methanol plant meets **Grade 1 standards**: Appearance: colorless and transparent liquid, without visible impurities. Colority (platinum-cobalt), value ≤ 5. Density (at 20°C), g/ml: 0.791–0.792. Boiling range (at 101.325 kPa), °C: 64.0–65.5. Temperature variation (including 64.6±0.1°C), °C ≤ 0.8. Potassium permanganate test, time ≥ 50 minutes. Water solubility: clear. Content of free acids (expressed as HCOOH), ppm ≤ 15. Content of free bases (expressed as NH3), ppm ≤ 2. Content of aldehyde compounds (expressed as HCOH), ppm ≤ 20. Evaporation residue, ppm ≤ 10. Odor: no unusual odors. Ethanol content, % ≤ 0.01
Table 1 Technical Requirements and Specifications: Grade, Standards, First-Class, Second-Class, Qualified
Chromaticity/Hazen units (platinum-cobalt color number) ≤ 5, 10
Density (ρ20)/g/cm3: 0.791–0.792, 0.791–0.793
Boiling range (at 0°C, 101.3 kPa, within the range of 64.0°C–65.5°C, including 64.6±0.1°C)/°C: ≤ 0.8, 1.0, 1.5
Potassium permanganate test/min: ≥ 50, 30, 20
Water miscibility test: Passes test (1+3), Passes test (1+9)
Mass fraction of water/%: ≤ 0.10, 0.15 –
Mass fraction of acid (as HCOOH)/%/≤ or mass fraction of base (as NH3)/%/≤ 0.0015, 0.0002, 0.0030, 0.0008, 0.0050, 0.0015
Mass fraction of carbonyl compounds (as HCHO)/%/≤ 0.002, 0.005, 0.010
Mass fraction of evaporation residue/%: ≤ 0.001, 0.003, 0.005
Sulfuric acid washing test/Hazen units (platinum-cobalt color number): ≤ 50
Mass fraction of ethanol/%: ≤ (to be determined through negotiation between supplier and buyer)—
Chromaticity/Hazen units (platinum-cobalt color number) ≤ 5, 10
Density (ρ20)/g/cm3: 0.791–0.792, 0.791–0.793
Boiling range (at 0°C, 101.3 kPa, within the range of 64.0°C–65.5°C, including 64.6±0.1°C)/°C: ≤ 0.8, 1.0, 1.5
Potassium permanganate test/min: ≥ 50, 30, 20
Water miscibility test: Passes test (1+3), Passes test (1+9)
Mass fraction of water/%: ≤ 0.10, 0.15 –
Mass fraction of acid (as HCOOH)/%/≤ or mass fraction of base (as NH3)/%/≤ 0.0015, 0.0002, 0.0030, 0.0008, 0.0050, 0.0015
Mass fraction of carbonyl compounds (as HCHO)/%/≤ 0.002, 0.005, 0.010
Mass fraction of evaporation residue/%: ≤ 0.001, 0.003, 0.005
Sulfuric acid washing test/Hazen units (platinum-cobalt color number): ≤ 50
Mass fraction of ethanol/%: ≤ (to be determined through negotiation between supplier and buyer)—