Acetylen Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
FARBLOSES GAS, UNTER DRUCK GELöST IN ACETON.
PHYSIKALISCHE GEFAHREN
Das Gas mischt sich gut mit Luft. Bildung explosionsfähiger Gemische.
CHEMISCHE GEFAHREN
Kann beim Erhitzen polymerisieren. Zersetzung beim Erhitzen und bei steigendem Druck unter Feuer- und Explosionsgefahr. Starkes Reduktionsmittel. Reagiert sehr heftig mit Oxidationsmitteln, sowie mit Fluor oder Chlor unter Lichteinfluss. Feuer- und Explosionsgefahr. Reagiert mit Kupfer, Silber und Quecksilber oder ihren Salzen unter Bildung schlagempfindlicher Verbindungen (Acetylide).
ARBEITSPLATZGRENZWERTE
TLV: Erstickungsgefahr durch Sauerstoffverdrängung; (ACGIH 2005).
MAK nicht festgelegt.
AUFNAHMEWEGE
Aufnahme in den Körper durch Inhalation.
INHALATIONSGEFAHREN
Beim Entweichen aus dem Behälter kann das Gas die Luft verdrängen. Erstickungsgefahr in geschlossenen Räumen.
WIRKUNGEN BEI KURZZEITEXPOSITION
WIRKUNGEN BEI KURZZEITEXPOSITION: Erstickungsgefahr.
LECKAGE
Gefahrenbereich verlassen! Fachmann zu Rate ziehen! Belüftung. Zündquellen entfernen. Persönliche Schutzausrüstung: Umgebungsluftunabhängiges Atemschutzgerät.
R-Sätze Betriebsanweisung:
R5:Beim Erwärmen explosionsfähig.
R6:Mit und ohne Luft explosionsfähig.
R12:Hochentzündlich.
S-Sätze Betriebsanweisung:
S9:Behälter an einem gut gelüfteten Ort aufbewahren.
S16:Von Zündquellen fernhalten - Nicht rauchen.
S33:Maßnahmen gegen elektrostatische Aufladungen treffen.
Beschreibung
Acetylene (100% purity) is odourless, but commercial purity has a distinctive garlic-like
odour and is very soluble in alcohol and almost miscible with ethane. Acetylene is a flammable
gas and kept under pressure in gas cylinders. Under certain conditions, acetylene
can react with copper, silver, and mercury to form acetylides, compounds which can act as
ignition sources. Brasses containing less than 65% copper in the alloy and certain nickel
alloys are suitable for acetylene. Acetylene is not compatible with strong oxidisers such as
chlorine, bromine pentafluoride, oxygen, oxygen difluoride and nitrogen trifluoride, brass
metal, calcium hypochlorite, heavy metals such as copper, silver, mercury, and their salts,
bromine, chlorine, iodine, fluorine, sodium hydride, caesium hydride, ozone, perchloric
acid, and potassium.
Chemische Eigenschaften
Acetylene (100% purity) is odorless but commercial purity has a distinctive garlic-like
odor. It is very soluble in alcohol and almost miscible with ethane. Acetylene is a flammable
gas and kept under pressure in gas cylinders. Under certain conditions, acetylene
can react with copper, silver, and mercury to form acetylides, compounds that can act as
ignition sources. Brasses contain a form acetylides, compounds that can act as ignition
sources. Brasses containing less than 65% copper in the alloy and certain nickel alloys are
suitable for acetylene. Acetylene is not compatible with strong oxidizers such as chlorine,
bromine pentafl uoride, oxygen, oxygen difl uoride, and nitrogen trifl uoride, brass metal,
calcium hypochlorite, heavy metals such as copper, silver, mercury, and their salts, bromine,
chlorine, iodine, fl uorine, sodium hydride, cesium hydride, ozone, perchloric acid,
or potassium.
Physikalische Eigenschaften
Acetylene, which is the simplest alkyne hydrocarbon, exists as a colorless, flammable, unstable gas with a distinctive pleasant odor (acetylene prepared from calcium carbide has a garlic smell resulting from traces of phosphine produced in this process). The term acetylenes is used generically in the petroleum industry to denote chemicals based on the carbon-carbon triple bond.
History
Acetylene was discovered in 1836 by Edmund Davy (1785-1857) who produced the gas while trying to make potassium metal from potassium carbide (K
2C
2). In 1859, Marcel Morren in France produced acetylene by running an electric arc between carbon electrodes in the presence of hydrogen. Morren called the gas produced carbonized hydrogen. Three years later, Pierre Eugène-Marcelin Berthelot (1827-1907) repeated Morren’s experiment and identified carbonized hydrogen as acetylene.
Verwenden
Illuminant, oxyacetylene welding, cutting, and soldering metals, signalling; pptg metals, particularly Cu; manufacture of acetaldehyde, acetic acid; fuel for motor boats.
Vorbereitung Methode
The traditional method of producing acetylene is from reacting lime, calcium oxide (CaO), with coke to produce calcium carbide (CaC
2). The calcium carbide is then combined with water to produce acetylene:
2CaO
(s) + 5C
(s)→2CaC
2(g) + CO
2(g)CaC
2(s) + 2H
2O
(l)→ C
2H
2(g) + Ca(OH)
2(aq)Several processes for producing acetylene from natural gas and other petroleum products developed in the 1920s. Thermal cracking of methane involves heating methane to approximately 600℃ in an environment deficient in oxygen to prevent combustion of all the methane. Combustion of part of the methane mix increases the temperature to approximately 1,500℃, causing the remaining methane to crack according the reaction: 2CH
4(g) → C2H
2(g) + 3H
2(g). In addition to methane, ethane, propane, ethylene, and other hydrocarbons can be used as feed gases to produce acetylene.
Definition
A
gaseous alkyne. Traditionally ethyne has
found use in oxy-acetylene welding
torches, since its combustion with oxygen
produces a flame of very high temperature.
It is also important in the organic chemicals
industry for the production of
chloroethene (vinyl chloride), which is the
starting material for the production of
polyvinyl chloride (PVC), and for the production
of other vinyl compounds. Until
recently, ethyne was manufactured by the
synthesis and subsequent hydrolysis of calcium
dicarbide, a very expensive procedure.
Modern methods increasingly
employ the cracking of alkanes.
Reaktionen
Acetylene reacts (1) with chlorine, to form acetylene tetrachloride C2H2Cl4 or CHCl2·CHCl2 or acetylene dichloride C2H2Cl2 or CHCl:CHCl, (2) with bromine, to form acetylene tetrabromide C2H2Br4 or CHBr2·CHBr2 or acetylene dibromide C2H2Br2 or CHBr:CHBr, (3) with hydrogen chloride (bromide, iodide), to form ethylene monochloride CH2:CHCl (monobromide, monoiodide), and 1,1-dichloroethane, ethylidene chloride CH3·CHCl2 (dibromide, diiodide), (4) with H2O in the presence of a catalyzer, e.g., mercuric sulfate HgO4S, to form acetaldehyde CH3·CHO, (5) with hydrogen, in the presence of a catalyzer, e.g., finely divided nickel heated, to form ethylene C2H4 or ethane C2H6, (6) with metals, such as copper or nickel, when moist, also lead or zinc, when moist and unpurified. Tin is not attacked. Sodium yields, upon heating, the compounds C2HNa and C2Na2. (7) With ammoniocuprous (or silver) salt solution, to form cuprous (or silver) acetylide C2Cu2, dark red precipitate, explosive when dry, and yielding acetylene upon treatment with acid, (8) with mercuric chloride solution, to form trichloromercuric acetaldehyde C(HgCl)3·CHO, precipitate, which yields with HCl acetaldehyde plus mercuric chloride.
Allgemeine Beschreibung
A colorless gas with a faint garlic-like odor. Easily ignited and burns with a sooty flame. Gas is lighter than air. Flame may flash back to the source of a leak very easily. Under prolonged exposure to fire or heat the containers may rupture violently and rocket.
Air & Water Reaktionen
Highly flammable. Slightly soluble in water. Reacts with water to form toxic ammonia fumes.
Reaktivität anzeigen
Acetylene reacts with alkali metals, forming Hydrogen gas. Acetylene can react explosively with bromine [Von Schwartz 1918. p.142 ]. Acetylene forms a sensitive acetylide when passed into an aqueous solution of mercuric nitrate, [Mellor 4:933. 1946-47]. An Acetylene torch used to drill through a plow frame, which was filled with hydrogen gas, produced an explosion [NIOSH, June 1998]. Acetylene reacts with silver, copper and lead to form sensitive, explosive salts. Since Acetylene is endothermic and effectively a reducing agent, it's reaction with oxidants can be very violent (examples: calcium hypochlorite, nitric acid, nitrogen oxide, ozone, trifluoromethyl hypofluorite, etc.). Contact of very cold liquefied gas with water may result in vigorous or violent boiling of the product and extremely rapid vaporization, due to the large temperature differences involved. If the water is hot, there is the possibility that a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if liquid gas contacts water in a closed container [Handling Chemicals Safely 1980]. Acetylene and ammonia can form explosive silver salts in contact with Ag. (Renner, Hermann, Gunther Schlamp. "Silver, Silver Compounds, and Silver Alloys." Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH Verlag GmbH & Co. KGaA. 2001.).
Hazard
The LEL of acetylene is reached well before asphyxiation can occur, and the danger of explosion is reached before any other health hazard is present. When fighting fires involving acetylene containers, the fire should be extinguished before closing the valve to the container. This is because the acetylene has such a wide flammable range that it can burn inside the container. Acetylene is incompatible with bromine, chlorine, fluorine, copper, silver, mercury, and their compounds. Acetylene has a four-digit UN identification number of 1001. The NFPA 704 designation is health 1, flammability 4, and reactivity 3. Reactivity is reduced to 2 when the acetylene is dissolved in acetone.
Health Hazard
Headache, dizziness and loss of consciousness may occur. Death from ``smothering'' may occur if oxygen content of the air is severely reduced by dilution with Acetylene.
Brandgefahr
Behavior in Fire: May explode in fire
Flammability and Explosibility
Acetylene is a highly flammable gas and forms explosive mixtures with air over an
unusually wide range of concentrations (2 to 80%). Acetylene can polymerize
exothermically, leading to deflagration. With a very high positive free energy of
formation, acetylene is thermodynamically unstable and is sensitive to shock and
pressure. Its stability is enhanced by the presence of small amounts of other
compounds such as methane, and acetylene in cylinders is relatively safe to handle
because it is dissolved in acetone. Acetylene fires can be fought with carbon dioxide,
dry chemical, and halon extinguishers; firefighting is greatly facilitated by shutting
off the gas supply.
Industrielle Verwendung
Acetylene is a colorless, flammable gas with a garlic-like odor. Under compressed conditions, it is highly explosive; however, it can be safely compressed and stored in high-pressure cylinders if the cylinders are lined with absorbent material soaked with acetone. Users are cautioned not to discharge acetylene at pressures exceeding 15 psig (103 kPa), as noted by the red line on acetylene pressure gauges.
With its intense heat and controllability, the oxyacetylene flame can be used for many different welding and cutting operations including hardfacing, brazing, beveling, gouging, and scarfing. The heating capability of acetylene also can be utilized in the bending, straightening, forming, hardening, softening, and strengthening of metals.
mögliche Exposition
Acetylene can be burned in air or oxygen and is used for brazing, welding, cutting, metallizing, hardening, flame scarfing; and local heating in metallurgy. The flame is also used in the glass industry. Chemically, acetylene is used in the manufacture of vinyl chloride, acrylinitrile, synthetic rubber; vinyl acetate; trichloroethylene, acrylate, butyrolactone, 1,4-butanediol, vinyl alkyl ethers, pyrrolidone, and other substances
Lager
Acetylene should be kept stored in a cool, dry place in a tightly sealed container, and
should only be used in a well-ventilated area. Cylinders should be separated from
oxygen and other oxidizers by a minimum of 20 ft or by a barrier of non-combustible material at least 5 ft high, having a fi re resistance rating of at least 30 min. Storage in
excess of 2500 cu ft is prohibited in buildings with other occupancies. Cylinders should
be stored upright with a valve protection cap in place and fi rmly secured to prevent
falling or being knocked over. The cylinders should be protected from physical damage
and avoid dragging, rolling, sliding, or dropping the cylinder. During transport, workers
should use a suitable hand truck for cylinder movement. Care should be taken to
label “No Smoking” or “Open Flames” signs in the storage or use areas. There should
be no sources of ignition. All electrical equipment should be explosion-proof in the storage
and use areas.
Versand/Shipping
UN1001 Acetylene, dissolved, Hazard Class: 2.1; Labels: 2.1-Flammable gas. Cylinders must be transported in a secure upright position, in a well-ventilated truck. Protect cylinder and labels from physical damage. The owner of the compressed gas cylinder is the only entity allowed by federal law (49CFR) to transport and refill them. It is a violation of transportation regulations to refill compressed gas cylinders without the express written permission of the owner
Inkompatibilitäten
The substance may polymerize due to heating. The substance decomposes on heating and increasing pressure, causing a fire and explosion hazard. The substance is a strong reducing agent and reacts violently with oxidants and with fluorine or chlorine under influence of light, causing fire and explosion hazard. Reacts with copper, silver, and mercury or their salts, forming shock-sensitive compounds (acetylides). The content of lines carrying acetylene must not exceed 63% copper. May form explosive mixture with air. Forms shock-sensitive mixture with copper and copper salts; mercury and mercury salts; and silver and silver salts. Reacts with brass, bromine, cesium hydride, chlorine, cobalt, cuprous acetylize; fluorine, iodine, mercuric nitrate; nitric acid, potassium, rubidium hydride; trifluoromethyl hypofluorite; and sodium hydride.
Waste disposal
Return refillable compressed gas cylinders to supplier. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration.
Acetylen Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
