Some standard content:
National Standard of the People's Republic of China
Methanol for industrial use
Methanol for industrial use
Subject content and scope of application
GB338-92
Replaces GB338-85|| tt||This standard specifies the technical requirements, test methods, inspection rules and marking, packaging, transportation, storage, etc. of industrial methanol. This standard applies to industrial methanol synthesized from coal, coke, natural gas, light oil, heavy oil, etc. as raw materials. Molecular formula: CH,OH
Relative molecular mass: 32.042 (according to the 1989 international relative atomic mass) 2 reference standards
GB190
GB601
GB1250
GB3143 | | tt | | GB4472 | | tt | Determination method of product color (Hazen unit - platinum - diamond color number) General rules for determination of density and relative density of chemical products Determination of moisture content in chemical products Karl Fischer method (general method) GB6324.1
GB6324.2
GB6678
GB6680
GB7534
GB8170
3 Technical requirements
Test method for water solubility of organic chemical products
Volatilization General Method for Determination of Dry Residues after Evaporation of Volatile Organic Liquids in Water Baths General Principles for Sampling Chemical Products Www.bzxZ.net
General Sampling Principles for Liquid Chemical Products
Rounding Rules for Determination of Boiling Ranges of Industrial Volatile Organic Liquids||tt| |3.1 Industrial methanol is a colorless and transparent liquid with no special odor and no visible impurities. Industrial methanol should meet the requirements of Table 1:
3.2
Table 1
Item
Color (Platinum-Diamond), No.
Density (20℃ ), g/cm
mesh
temperature range (0℃, 101325Pa), C boiling range (including 64.6±0.1℃),
State Bureau of Technical Supervision 1992-09-28 Approved superior product
0.791~0.792
0.8
5
refers to
first-class product
standard
qualified product
10
0.791~0.793
64.0~65.5
1.0
1.5
Implemented on 1993-08-01
Item
Potassium permanganate test, min
Water solubility test
Moisture content, %
Acidity (based on HCOOH), %
or alkali Degree (based on NH,), %
carbonyl compound content (based on CH.O), % evaporation residue content, %
Test method
4
GB338 —92
Continued Table 1
Premium product
50
0.10
0.0015
0.000 2
0.002|| tt||0. 001
clarification
refers to
first-class product
30
0.15
standard
0.003 0
0.000 8
0.005
0.003
Unless otherwise noted, the reagents and water used in this test method are analytically pure reagents and distilled water or water of equivalent purity . Determination of chromaticity
4.1
Measured according to the provisions of GB3143.
4.2 Determination of density
4.2.1 Densitometer method
Qualified product
20
0.0050
0.0015
0.010
0.005
4.2.1.1 According to the provisions of 2.3.3 in GB4472, the measurement is carried out at room temperature. The indication range of the density meter is 0.750~0.800g/cm. Within the temperature range of 15 to 35°C, the temperature correction coefficient K value of the sample density is 0.00093g/cm2°C. Take the arithmetic mean of two parallel measurements as the result. 4.2.1.2 The allowable difference
is that the difference between two parallel measurement results shall not be greater than 0.0005g/cm. 4.2.2 Pycnometer method (arbitration method)
4.2.2.1 Measure according to the provisions of 2.3.1 in GB4472. Take the arithmetic mean of two parallel measurements as the result. 4.2.2.2 The allowable difference
is that the difference between two parallel measurement results shall not be greater than 0.0005g/cm. 4.3 Determination of boiling range
shall be measured according to the provisions of GB7534. The indication range of the main thermometer is 50~70℃, and the condenser specifications comply with the requirements of GB7534 3.4.1.
The correction value of the boiling point temperature due to the change in air pressure should comply with the requirements in Table 2. Table 2
Air pressure, kPa
R value, C/Pa
4.4 Potassium permanganate test
4.4.1 Principle
773~813| |tt||2.78×10-4
814~866
2.70×10-*
867~933
2.62×10-*
934~986
2.55×10
Methanol contains reducing impurities, which react with potassium permanganate in a neutral solution and reduce potassium permanganate to manganese dioxide 4.4.2 Instruments|| tt||Water bath: control temperature 15±0.5℃, KF-4 type low temperature constant temperature water bath or equivalent precision instrument; 4.4.2.1
4.4.2.2
4.4.2.3
Ratio Color tube: 50mL, colorless glass product, with glass ground stopper; Pipette: 2mL.
087~1066
2.48×10-*
GB338-92
4.4.3 Reagents and solutions
4.4.3.1 Preparation of water: take Add enough dilute potassium permanganate solution to an appropriate amount of water to turn it into a stable pink color, and boil for 30 minutes. If the pink color disappears, add potassium permanganate solution and it will turn pink again, then let it cool and set aside. This solution is prepared when used. 4.4.3.2 Preparation of potassium permanganate solution: Accurately weigh 0.200g of potassium permanganate and place it in a 1000mL brown volumetric flask, dissolve it with water (4.4.3.1), dilute to the mark, and shake well. Store sealed in a dark place and has a one-week shelf life. 4.4.3.3 Preparation of color standard: Weigh 2.5000g cobalt chloride (CoClz·6H,0) and 2.8000g uranyl nitrate [UO(NO,)·6H.O) and dissolve them in water, quantitatively transfer them to a 1000mL volumetric flask and add 10mL nitric acid solution [c (HNO.) = 2mol/L], dilute to volume with water, shake well and set aside. This solution has a shelf life of three months. 4.4.4 Analysis steps
Before measurement, soak the instrument used in hydrochloric acid (1+1) in advance, then wash it with tap water, then wash it with distilled water and dry it. Use a pipette to take 50 mL of methanol sample at about 15°C, pour it into the colorimetric tube, and place it in a water bath at 15 ± 0.5°C. The water surface in the water bath should be higher than the horizontal line of the sample in the colorimetric tube. After 15 minutes, take out the colorimetric tube from the water bath, add 2mL of potassium permanganate solution with a pipette, and record the time when the first drop is added. Cover and stopper, shake well, and return to the water bath. After that, take out another colorimetric tube with an equal volume of color standard from the water bath at certain intervals (this tube does not need to be placed in the water bath), and observe the color change of the methanol sample sideways against a white background. Note: Avoid exposing the sample solution to direct sunlight to prevent potassium permanganate from decomposing. Record the time when the color change of the methanol sample is consistent with the color of the color scale. This time range is the measurement time of the potassium permanganate test. 4.4.5 The allowable difference
is that the difference between parallel measurement results shall not exceed 3 minutes. 4.5 Water solubility test
is measured according to the provisions of GB6324.1. Select the miscibility ratio of the sample to water as follows: 1 to 3 for excellent products and 1 to 9 for first-class products. 4.6 Determination of moisture
4.6.1 Measure according to the provisions of GB6283, and the volume of the sample taken is 10.0mL. Take the arithmetic mean of two parallel measurements as the result. 4.6.2 The allowable difference
is that the difference between two parallel measurement results shall not be greater than 0.01%. 4.7 Determination of acidity or alkalinity
4.7.1 Principle
The methanol sample is diluted with water without carbon dioxide, and bromothymol blue indicator is added. If the sample is acidic, use sodium hydroxide standard titration solution to neutralize the free acid. If the sample is alkaline, use Standard titration solution of sulfuric acid neutralizes the free base. 4.7.2 Reagents and solutions
4.7.2.1 Sodium hydroxide standard titration solution: c (NaOH) = 0.01mol/L; 4.7.2.2 Sulfuric acid standard titration solution: c (No. H, SO,) = 0.01mol /L; 4.7.2.3 Bromothymol blue solution: Weigh 0.1g of bromothymol blue and dissolve it in 50% ethanol, and dilute to 100mL. 4.7.2.4 Preparation of carbon dioxide-free water: Put distilled water into a flask and boil for 10 minutes , immediately plug the stopper of the alkali asbestos glass tube and let it cool before use.
4.7.3 Instruments
4.7.3.1 Burette: capacity 10mL, graduation 0.05mL, 4.7.3.2 Erlenmeyer flask: 250~300mL.
4.7.4 Analysis steps
The methanol sample is diluted with an equal amount of carbon dioxide-free water, and the bromothymol blue solution is added for identification. The yellow color indicates an acidic reaction and the acidity is measured, and the blue color indicates an alkali. Sexual reaction, measure alkalinity. Take 50 mL of carbon dioxide-free water, pour it into an Erlenmeyer flask, and add 4 to 5 drops of bromothymol blue solution. When measuring free acid, titrate with GB338-92
sodium hydroxide standard titration solution until it turns light blue (excluding the volume of sodium hydroxide standard titration solution consumed), and then add 50 mL methanol sample with a 50 mL pipette , titrate with sodium hydroxide standard titration solution until the solution changes from yellow to light blue and does not fade for 30 seconds, which is the end point. When measuring free base, titrate with sulfuric acid standard titration solution until the solution changes from blue to yellow, and the end point is when it does not change color for 30 seconds. 4.7.5 Expression of results
Acidity |tt||X, =V× 0. 046 × 100
50p.
：c.
The actual concentration of sodium hydroxide standard titration solution, mol/LV
0.046-
e,
C2
Titration consumption of hydrogen oxide Volume of sodium standard titration solution, mL; (1)
(2)
equivalent to 1.00mL sodium hydroxide standard titration solution (c(NaOH) = 1.000mol/L), in grams represents the mass of formic acid;
the density of the methanol sample at temperature t, g/cm; the actual concentration of the sulfuric acid standard titration solution, mol/L; V, - the volume of the sulfuric acid standard titration solution consumed by the titration, mL; equivalent to 1.00mL of sulfuric acid standard titration solution (c (No. H, SO,) = 1.000mol/L), the mass of ammonia expressed in grams is 0.017-
.
Take the arithmetic mean of two parallel measurements as the result. 4.7.6 Allowable difference
The relative deviation of the results of two parallel measurements shall not exceed 30%. 4.8 Determination of carbonyl compound content
4.8.1 Principle
The carbonyl compound in the methanol sample reacts chemically with 2,4-dinitrophenylhydrazine in the acidic medium to generate 2,4 -Dinitrobenzene. After the solution is converted to alkaline, it becomes reddish brown. Measurements were made with a spectrophotometer at a wavelength of 430 nm. 4.8.2 Reagents and solutions
4.8.2.1 Acetophenone (CH, COCH,); 4.8.2.22, 4-dinitrophenylhydrazine;
4.8.2.3 Hydrochloric acid; ||tt| |4.8.2.4 Potassium hydroxide;
4.8.2.5 Preparation of carbonyl-free methanol: Put 1L methanol into a distillation bottle, add 6g 24-dinitrobenzene, 10 drops of hydrochloric acid, and place the distillation bottle in a water bath , install a reflux condenser, heat to boiling and reflux for 3 to 4 hours, then leave it overnight, install a suitable fractionating column and condenser for slow distillation, discard 75 mL of the initial distillate, receive 850 mL of subsequent distillate, and discard the rest. go. If the distillate is colored, the stuffing should be steamed again,
4.8.2.6 Potassium hydroxide solution: Weigh 10g potassium hydroxide, dissolve it in 20mL water, add 80mL carbonyl-free methanol after cooling, and mix evenly. Prepare on the same day;
4.8.2.72, 4-dinitrophenyl hydrazine solution: weigh about 0.03g of 2,4-dinitrophenylhydrazine, weigh accurately to 0.001g, dissolve in 49mL of carbonyl-free methanol, and add 1.5mL hydrochloric acid, mix well. Prepare on the same day; 4.8.2.8 Preparation of carbonyl compound standard solution: Use the syringe reduction method (the needle tip is sealed with silicone rubber), weigh 1.200g acetophenone and inject it into a 100mL dry volumetric flask, and dilute to the mark with carbonyl-free methanol Mix well. This solution is solution A; put 1 mL of solution A into a 100 mL dry volumetric flask, dilute to the mark with carbonyl-free methanol, and shake. This solution is solution B. 1mL of this GB338-92
solution contains 0.00012g of acetophenone, which is equivalent to 30μg of formaldehyde. 4.8.3 Instruments
4.8.3.1 Water bath: controllable temperature 50±2℃; 4.8.3.2 Colorimetric tube: capacity 25mL, colorless glass product, with glass ground stopper; 4.8.3.3 Pipette: Capacity: 1, 2, 10mL, graduation 0.1mL; 4.8.3.4 Volumetric flask: capacity: 25, 100mL; 4.8.3.5 Spectrophotometer.
4.8.4 Drawing of standard curve of carbonyl compounds Take several 25mL volumetric flasks, add solution B0, 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, 20.0mL accurately respectively, and dilute with carbon-free methanol to The scale is equivalent to containing 0, 3, 6, 9, 12, 15, 18, and 24 μg of formaldehyde per milliliter. From each of the above volumetric flasks, take 1 mL of each solution and place it in a colorimetric tube. Add 1 mL of 2,4-dinitrobenzene solution to each colorimetric tube, cover the stopper tightly, put it into a water bath, keep at 50 ± 2°C, take it out after 30 minutes, cool to room temperature, and add to each colorimetric tube respectively. Add 5 mL of potassium hydroxide solution, mix well, and leave for 15 minutes. Use a spectrophotometer to measure the absorbance of each standard solution at a wavelength of 430 nm (use a 5 to 10 mm cuvette and use a reagent compensation solution to adjust the absorbance to zero). Draw a standard curve with the measured absorbance value as the ordinate and the formaldehyde content of the standard solution as the abscissa. The useful life of this curve is 3 months. 4.8.5 Analysis steps
Use a pipette to take 1 mL of methanol sample and place it in a colorimetric tube. Take 1 mL of carbon-free methanol in another colorimetric tube to adjust the zero point of the absorbance. The steps for measuring absorbance are as per 4.8.4. Use the measured absorbance of the sample to find the mass equivalent to the formaldehyde content (μg) from the standard curve. If the carbonyl compound in the methanol sample exceeds the curve range, take 0.5 mL of the sample and dilute it to 1 mL with carbonyl-free methanol. 4.8.6 Expression of results
Carbonyl compound (calculated as HCOH) content In the formula: m - the amount of formaldehyde detected from the standard curve, ug; V the volume of the methanol sample, mL;
P, - the density of the methanol sample at temperature t, g/cm. Take the arithmetic mean of the two parallel measurement results as the result. 4.8.7 The allowable difference
is that the relative deviation of parallel measurement results does not exceed 20%. 4.9 Determination of evaporation residue
4.9.1 Determination shall be carried out according to the provisions of GB6324.2. Take the arithmetic mean of two parallel measurements as the result. 4.9.2 The allowable difference
is that the difference between two parallel measurement results shall not be greater than 0.0003%. 5 Inspection Rules
·(3)
5.1 Industrial methanol should be inspected by the quality inspection department of the manufacturer. The manufacturer should ensure that every batch of industrial methanol shipped meets the requirements of this standard.
5.2 Each batch of industrial methanol leaving the factory should be accompanied by a quality certificate in a certain format. The content includes: manufacturer name, product name, batch number, production date, product quality and this standard number. 5.3 Industrial methanol shall be sampled according to the provisions of Table 2 in GB6678. If the total number of units sampled is greater than 500, sampling should be carried out as three times the cube root of the total number of units, that is, 3×/N (N is the number of total units). The sampling method is carried out according to 2.1.3 in GB6680. GB338-92
(Product quality issues related to user-provided containers shall be resolved through negotiation between the supply and demand parties). 5.4. The total amount of sampled products shall not be less than 2L. After the samples are fully mixed, they are divided into two dry and clean glass bottles with ground stoppers. Label them and indicate the name of the manufacturer, product name, batch number, Date of sampling and name of sampler. One bottle is used for inspection and analysis, and one bottle is kept for one month for inspection.
5.5 Water solubility test and evaporation residue are randomly inspected once a month. 5.6 The user has the right to verify the quality of the industrial methanol received in accordance with the provisions of this standard. 5.7 When manufacturers and users inspect products, if they find that any indicator in the inspection results does not meet the requirements of this standard, they should re-sample for inspection. If even one of the results obtained does not meet the requirements of this standard, the entire batch of products will be deemed unqualified. 5.8 When a dispute arises between the supply and demand parties over product quality, arbitration shall be conducted in accordance with the provisions of the "Interim Measures for National Product Quality Arbitration and Inspection". 5.9 When implementing this standard, the rounded value comparison method is used to determine the results, and the results are determined in accordance with the provisions of the rounded value comparison method in GB1250. Numerical rounding shall be carried out in accordance with the provisions of GB8170. The number of significant digits of the numerical value should be consistent with the technical specifications. 6 Marking, packaging, transportation and storage
6.1 Industrial methanol product packaging containers should be painted with firm marks, which include: manufacturer name, product name, this standard number, trademark, batch number, net weight and GB190 Figure 5 "Flammable Liquid Sign" and Figure 11 "Drugs Sign". 6.2 Industrial methanol should be packaged in clean and dry iron tank cars and strong iron barrels (net weight 150kg per barrel). Packaging containers should be tightly sealed. 6.3 Methanol should be stored in a dry, ventilated, and low-temperature warehouse. Protected from direct sunlight and insulated from heat sources and fire. Storage period is 6 months. 6.4 Safety measures: Methanol is a colorless flammable liquid with a flash point of 8°C and an auto-ignition temperature of 436°C. The explosion range of its vapor content in the air is 6% to 36.5%. If methanol spills, rinse immediately with water. In case of fire, use sand, foam fire extinguisher, asbestos cloth, etc. to put out the fire. Contact between methanol and skin should be avoided. If it splashes on the skin or eyes, rinse immediately with plenty of water. Methanol vapor has a stimulating effect on the nervous system. When inhaled into the human body, it can cause blindness and poisoning. If any of the above situations occur, seek immediate medical treatment. Additional notes:
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the technical jurisdiction of the Beijing Research Institute of Chemical Industry of the Ministry of Chemical Industry. This standard is drafted by the Fertilizer Factory of Jilin Chemical Industry Company and the Beijing Research Institute of Chemical Industry of the Ministry of Chemical Industry. The main drafters of this standard are Yang Anqun, Li Lanqing, Gao Guoru and Fu Zhensheng. This standard refers to the American Society for Testing and Materials standard ASTMD1152-84 "Methanol".
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