H
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H-C-O-H
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H
Molecular structure: C atoms bonded by sp3 hybridized orbitals, 0 atoms bonded by sp3 hybridized orbitals are bonded. The molecule is polar.
CAS Registry Number: 67-56-1
EINECS Registry Number: 200-659-6
Physical and Chemical Properties
Methanol is a colorless, transparent, flammable, volatile and poisonous liquid, with a slight odor of alcohol. Molecular weight 32.04, relative density 0.792 (20/4 ° C), melting point -97.8 ° C, boiling point 64.5 ° C, flash point 12.22 ° C, spontaneous combustion point 463.89 ° C, vapor density 1.11, vapor pressure 13.33 KPa (100 mmHg 21.2 ° C), vapor and air mixture explosion lower limit 6-36.5 %, can be with water, ethanol, ether, benzene, Can be miscible with water, ethanol, ether, benzene, ketone, halogenated hydrocarbons and many other organic solvents, easily combustible when exposed to heat, open flame or oxidizer. Combustion reaction formula:
CH3OH + O2 → CO2 + H2O
Use
Methanol has a wide range of uses, it is the basic organic chemical raw materials and high quality fuel. Mainly used in fine chemicals, plastics and other fields, used to make formaldehyde, acetic acid, chloromethane, methyl ammonia, dimethyl sulfate and many other organic products, but also one of the important raw materials for pesticides and pharmaceuticals. Methanol can be used as a new type of clean fuel after deep processing, and also added to gasoline blending.
Method
Methanol production, mainly synthetic method, there are still a small amount of wood distillation as a by-product recovery. Synthesis of the chemical reaction formula is:
H2 + CO → CH3OH
Synthesis of methanol can be solid (such as coal, coke) liquids (such as crude oil, heavy oil, light oil) or gases (such as natural gas and other flammable gases) as a raw material, by the creation of a gas purification (desulphurization) transformations, to remove carbon dioxide, the preparation of a certain amount of syngas (carbon monoxide and hydrogen). Different process conditions are selected in the presence of different catalysts. Methanol production alone (divided into high-pressure method low-pressure and medium-pressure method), or with synthetic ammonia co-production of methanol (coalcohol method). The synthesized crude methanol is pre-distilled to remove methyl ether and distilled to produce finished methanol. High-pressure method is the first BASF method to realize industrial synthesis, but because of its high energy consumption, complex processing, harsh material requirements, and many by-products in the product, it will be replaced by ICI low-pressure and medium-pressure method and Lurgi low-pressure and medium-pressure method in the future.
Safety mechanism
Methanol is well known to the public because of its toxicity. Industrial alcohol contains about 4% methanol, which is used by unscrupulous people as cooking alcohol to make fake alcohol, and when it is consumed by people, methanol poisoning occurs. The fatal dose of methanol is about 70 milliliters.
Methanol has strong toxicity and has the greatest impact on the human nervous system and blood system, it is ingested through the digestive tract, the respiratory tract or the skin will produce a toxic reaction, and methanol vapor can damage the mucous membranes of the human respiratory tract and eyesight. Acute poisoning symptoms include: headache, nausea, stomach pain, fatigue, blurred vision to blindness, followed by respiratory distress, which eventually leads to paralysis of the respiratory center and death. Chronic toxic reactions are: dizziness, lethargy, headache, ringing in the ears, loss of present strength, and digestive disturbances. Methanol intake of more than 4 grams will appear toxic reaction, accidentally take a small cup of more than 10 grams can cause blindness, drinking a large amount of death. Lethal dose of more than 30 milliliters, methanol in the body is not easy to discharge, will be accumulated, oxidation in the body to generate formaldehyde and formic acid are also toxic. In the methanol production plant, the relevant departments of our country, the air allowed methanol concentration of 5mg/m3, methanol gas in the work of the site must wear gas masks, wastewater to be treated before discharge, the allowable content of less than 200mg / L
Methanol poisoning mechanism is that methanol metabolized by the body to produce formaldehyde and formic acid (commonly known as anthranilic acid), and then the human body to produce harm. Common symptoms are a feeling of drunkenness, followed hours later by headaches, nausea, vomiting, and blurred vision. In severe cases, blindness and even death can occur. Blindness occurs when formic acid, a metabolite of methanol, accumulates in the eye area and destroys visual nerve cells. Brain nerves are also damaged, producing permanent damage. When formic acid enters the bloodstream, it makes the tissues more and more acidic and damages the kidneys leading to kidney failure.
Methanol poisoning can usually be detoxified with ethanol. The principle is that methanol itself is non-toxic, while the metabolites are toxic, so it can be detoxified by inhibiting metabolism. Methanol and ethanol metabolism in the body are the same enzyme, and this enzyme and ethanol more affinity. Therefore, methanol poisoning, you can drink strong alcohol (alcohol content is usually more than 60 degrees) to ease the methanol metabolism, and then make it out of the body. And formic acid, which is already produced by methanol metabolism, can be neutralized by taking baking soda (sodium bicarbonate).
Leakage Emergency Response
Rapidly evacuate people in the leaking contaminated area to a safe area and isolate them, strictly restricting access. Cut off the source of fire. It is recommended that emergency personnel wear self-contained positive-pressure respirators and anti-static work clothes. Do not come into direct contact with the leak. Cut off the source of leakage as far as possible. Prevent flow into restricted spaces such as sewers and flood drains. Small leaks: adsorb or absorb with sand or other non-combustible materials. May also be flushed with large amounts of water, diluted with wash water and placed in the wastewater system. Large quantity spills: Construct a dike or dig a pit to contain the spill. Cover with foam to reduce vapor hazard. Use explosion-proof pumps to transfer to tanker trucks or special collectors, recycling or transported to the waste treatment site for disposal.
Methanol gasoline
Methanol gasoline refers to the methanol partially added to gasoline, with methanol fuel co-solvents compounded M series of blended fuel. Among them: M15 (15% methanol added to gasoline) clean methanol gasoline for automotive fuels, respectively, applied to a variety of gasoline engines, can be used in place of finished gasoline without changing the conditions of the current engine structure, and can be blended with finished oil. Methanol blended fuel has good thermal efficiency, power, start-up and economy, and is characterized by lower emissions, oil savings, safety and convenience. Countries around the world have developed methanol gasoline with different blending ratios such as M3, M5, M15, M20, M50, N85, M100, etc. according to different national conditions. At present, commercial methanol is mainly M85 (85% methanol + 15% gasoline) and M100, M100 performance is better than M85, with greater environmental superiority.