ЭТАН

Описание

Ethane is a colorless, odorless, flammable gas that is relatively inactive chemically and is considered nontoxic. It is shipped as a liquefied compressed gas under its vapor pressure of 544 psig at 70°F (3750 kPa at 21.1℃).

Химические свойства

Ethane is a compressed, liquefied, colorless gas. Mild, gasoline-like odor. Odorless when pure.

История

Ethane was first synthesized in 1834 by Michael Faraday (1791–1867) through the electrolysis of acetate solutions, although Faraday believed the compound was methane. Twenty years later Adolph Wilhelm Hermann Kolbe (1818–1884) incorrectly identified ethane as the methyl radical in his research, and Edward Frankland (1825–1899) prepared ethane by treating ethyl iodine (C₂H₅I) with metals.

Использование

In the manufacture of chlorinated derivatives; as refrigerant in some two-stage refrigeration systems where relatively low temperatures are produced; as fuel gas (so called "bottled gas" or "suburban propane" contains about 90% propane, 5% ethane, and 5% butane).

Определение

A gaseous alkane obtained either from the gaseous fraction of crude oil or by the ‘cracking’ of heavier fractions. Ethane is the second member of the homologous series of alkanes.

Методы производства

The synthesis of ethane takes place through a process called Kolbe synthesis. In this processacetic acid (CH₃COOH) undergoes electrolysis to oxidize acetate ions at the anode of an electrochemicalcell to produce acetate radicals: CH₃COO- → CH₃COO?. Two acetate radicals thencombine to give ethane and carbon dioxide: CH₃COO? + CH₃COO? → C₂H₆ + 2CO₂.

Общее описание

A colorless odorless gas. ETHANE is easily ignited. The vapors are heavier than air. ETHANE can asphyxiate by the displacement of air. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. Contact with the liquid may cause frostbite.

Реакции воздуха и воды

Highly flammable.

Профиль реактивности

Saturated aliphatic hydrocarbons, such as ETHANE, may be incompatible with strong oxidizing agents like nitric acid. Charring of the hydrocarbon may occur followed by ignition of unreacted hydrocarbon and other nearby combustibles. In other settings, aliphatic saturated hydrocarbons are mostly unreactive. They are not affected by aqueous solutions of acids, alkalis, most oxidizing agents, and most reducing agents. Peroxidizable

Опасность

Severe fire risk if exposed to sparks or open flame. Flammable limits in air 3–12%. An asphyxiant gas.

Угроза здоровью

Like methane, ethane is a nonpoisonous gas.It is a simple asphyxiate. At high concentrationsit may exhibit narcotic effects.

Пожароопасность

EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Vapors from liquefied gas are initially heavier than air and spread along ground. CAUTION: Hydrogen (UN1049), Deuterium (UN1957), Hydrogen, refrigerated liquid (UN1966) and METHANE (UN1971) are lighter than air and will rise. Hydrogen and Deuterium fires are difficult to detect since they burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.) Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.

Использование в материалах

Ethane is noncorrosive and may be contained in installations constructed of any common metals designed to withstand the pressure involved.

Профиль безопасности

A simple asphyxiant. See ARGON for properties of simple asphyxiants. A very dangerous fire hazard when exposed to heat or flame; can react vigorously with oxidizing materials. Moderate explosion hazard when exposed to flame. To fight fire, stop flow of gas. Incompatible with chlorine, doxygenyl tetrafluoroborate, oxidizing materials, heat or flame. When heated to decomposition it emits acrid smoke and irritating fumes.

Возможный контакт

Ethane is used as a fuel, in making chemicals or as a freezing agent. The health effects caused by ethane exposure are much less serious than the fire and explosion risk posed by this chemical

Канцерогенность

Syrian hamster embryo cells were exposed in vitro to ethane gas. After exposure, the cells were removed and assayed for viability and increased sensitivity to viral transformation. Ethane was determined to be inactive.

хранилище

All the precautions required for the safe handling of any flammable compressed gas must be observed with ethane. It is important that ignition sources be kept away from containers, including situations where leakage could cause the gas to ignite by such sources as a spark from a motor. AlI piping and equipment used with ethane should be grounded.
Ethane should not be stored with cylinders containing oxygen, chlorine, or other oxidizing or combustible materials.

Перевозки

UN1035 (compressed gas); UN1961 (refrigerated liquid): Ethane, 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.

Методы очистки

Ethylene can be removed by passing the gas through a sintered-glass disc into fuming H2SO4 then slowly through a column of charcoal saturated with bromine. Bromine and HBr are removed by passage through firebrick coated with N,N-dimethyl-p-toluidine. The ethane is also passed over KOH pellets (to remove CO2) and dried with Mg(ClO4)2. Further purification is by several distillations of liquified ethane, using a condensing temperature of -195o. Yang and Gant [J Phys Chem 65 1861 1961] treated ethane by standing it for 24hours at room temperature in a steel bomb with activated charcoal treated with bromine. They then immersed the bomb in a Dry-ice/acetone bath and transferred the ethane to an activated charcoal trap cooled in liquid nitrogen. (The charcoal had previously been degassed by pumping for 24hours at 450o.) By allowing the trap to warm slowly, the ethane distils, and only the middle third fraction is kept. Removal of methane is achieved using Linde type 13X molecular sieves (previously degassed by pumping for 24hours at 450o) in a trap which, after cooling in Dry-ice/acetone, is saturated with ethane. After pumping for 10minutes, the ethane is recovered by warming the trap to 25o. (The final gas contains less than 10-4 mole % of either ethylene or methane). [Beilstein 1 IV 108.]

Несовместимости

Flammable gas; forms explosive mixture with air. Strong oxidizers may cause fire and explosions. May accumulate static electrical charges, and may cause ignition of its vapors.

Утилизация отходов

Return refillable compressed gas cylinders to supplier. Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber. All federal, state, and local environmental regulations must be observed.