CARBON MONOXIDE

Description

Carbon monoxide is a colorless, odorless, tasteless, flammable, toxic gas.Carbon monoxide is produced when carbon and carbon compounds undergo incomplete combustion. The inefficient combustion of carbon fuels for heating results in the production of carbon monoxide, which may result in high CO concentrations in indoor environments. The use of carbon fuel heaters without adequate ventilation can result in deadly conditions. Each year several hundred people in the United States die from CO poisoning, and 10,000 patients are treated in hospitals for CO exposure.Cars and other forms of transportation are a major source of carbon monoxide pollution in cities.

Chemical Properties

Carbon monoxide, CO, is a colorless,odorless, toxic gas. It is soluble in alcohol and cuprix chloride solutions, but insoluble in water. Carbon monoxide is formed by the incomplete oxidation of carbon. It is found in mines and carexhaust. Carbon monoxide is used in metallurgy as a reducing agent in smelting operations, in the production of carbony is for the separation of various metals, as an ingredient in the synthesis of phosgene,and as an intermediate in the production of methanol.

Because it is only slightly less dense than air, it mixes readily without stratification. Because it is only slightly less dense than air, it mixes readily without stratification. Because of its low boiling point, carbon monoxide is shipped as a nonliquified compressed gas. It is also known as carbon oxide, flue gas, and monoxide. Carbon monoxide is a flammable gas and is incompatible or reactive with strong oxidizers, such as bromine trifluoride, chlorine trifluoride, and lithium.

Physical properties

Colorless, odorless and tasteless gas; density 1.229 g/L; very flammable,burns in air with a bright blue flame; liquefies at -191.5°C; solidifies at -205°C; critical temperature -140°C, critical pressure 34.53 atm, critical vol ume 93 cm³/mol; soluble in chloroform, acetic acid, ethyl acetate, ethanol, and ammonium hydroxide; sparingly soluble in water (2.3 mL/100 mL water at 20°C).

Occurrence

Carbon monoxide is found in varying concentrations in unventilated and confined spaces resulting from partial oxidation of carbonaceous matter. Burning wood, paper, kerosene, or other organic materials in inadequate air can produce this gas. It also is found in automobile exhaust and tobacco smoke emissions.
Carbon monoxide has many important industrial applications. It is used in Fischer-Tropsch process to produce liquid or gaseous hydrocarbons, synthet ic fuels and many oxygenated derivatives. This process was applied before and during World War II to produce synthetic fuels. Probably the most important application of this compound involves production of oxygenated organics in the Synthol process and in oxo synthesis. Many aliphatic alcohols, alehydes and ketones are produced by catalytic hydrogenation of carbon monoxide. Oxo synthesis produces aldehydes from olefins. Carbon monoxide also is the start ing material for preparing metal carbonyls. In metallurgy, it is used as a reducing agent to reduce oxides. In the Mond process it recovers nickel.

History

Carbon monoxide is a colorless, odorless, tasteless, flammable, toxic gas. It was first identified by the Spanish alchemist Arnold of Villanova (1235–1313), who noted the production of a poisonous gas when wood was burned. The formal discovery of carbon monoxide is credited to the French chemist Joseph Marie Fran?ois de Lassone (1717–1788) and the British chemist Joseph Priestley (1733–1804). The former prepared carbon monoxide by heating carbon in the presence of zinc, and for a time the compound was incorrectly identified as hydrogen. William Cumberland Cruikshank (1745–1800) correctly determined that carbon monoxide was an oxide of carbon in 1800.

Uses

Carbon monoxide is used in the oxo processor Fischer–Tropsch process in the produc tion of synthetic fuel gas (producer gas, watergas, etc.); as a reducing agent in the Monodprocess for the recovery of nickel; in car bonylation reactions; and in the productionof metal carbonyls and complexes. It is pro duced by incomplete combustion of organicmaterials. Risk of exposure to this gas arisesunder fire conditions; from a burning stoveor from burning wood or candles in a closedroom; in the exhausts of internal combustion engines; in a closed garage with theautoengine on; and from oil or gas burners,improperly adjusted.

Uses

Carbon monoxide bonds to the iron in hemoglobin to form carboxyhemoglobin, which interferes with oxygen’s ability to bind to hemoglobin to form oxyhemoglobin. Thus carbon monoxide is a chemical asphyxiant, which prevents oxygen from reaching body tissues.
Carbon monoxide is an important industrial chemical. It is produced, along with hydrogen, by steam reforming. Carbon monoxide is a basic feedstock in these processes.
Carbon monoxide is also useful as a reducing agent. It is used in metallurgy to obtain metals from their oxides. For example, during iron and steel production coke in a blast furnace is converted to carbon monoxide. The carbon monoxide reduces the Fe³⁺ in the iron (III) oxide contained in the iron ore to produce elemental iron according to the reaction: Fe₂O_3(s) + 3CO_(g) → 2Fe_(l) + 3CO_2(g).

Uses

As reducing agent in metallurgical operations especially in the Mond process for the recovery of nickel; in organic synthesis especially in the Fischer-Tropsch processes for petroleum-type products and in the oxo reaction; in the manufacture of metal carbonyls.

Definition

A colorless flammable toxic gas formed by the incomplete combustion of carbon. In the laboratory it can be made by dehydrating methanoic acid with concentrated sulfuric acid:
HCOOH – H₂O → CO
Industrially, it is produced by the oxidation of carbon or of natural gas, or by the water-gas reaction. It is a powerful reducing agent and is used in metallurgy.
Carbon monoxide is neutral and only sparingly soluble in water. It is not the anhydride of methanoic acid, although under extreme conditions it can react with sodium hydroxide to form sodium methanoate. It forms metal carbonyls with transition metals, and its toxicity is due to its ability to form a complex with hemoglobin.

Production Methods

Carbon monoxide is formed during combustion of carbonaceous materials in oxygen (when carbon is in excess), or it can be formed (with oxygen) by thermal decomposition of carbon dioxide (>2000° °C). It can be generated by improperly vented cooking and heating appliances including coal stoves, furnaces, and gas appliances when the oxygen supply is insufficient. Other sources include exhaust of internal combustion engines, structural fires, and tobacco products. Carbon monoxide can also be formed endogenously by normal heme turnover or during the metabolism of selected hydrocarbons, such as methylene chloride. Not surprisingly, CO is one of the most common agents of inadvertent human intoxication in both occupational and nonoccupational environments.

Reactions

Chemically, carbon monoxide is (1) reactive with oxygen to form CO2 accompanied by a transparent blue flame and the evolution of heat, but the fuel value is low (320 Btu per ft3), (2) reactive with chlorine, forming carbonyl chloride COCl2 in the presence of light and a catalyzer, (3) reactive with sulfur vapor at a red heat, forming carbonyl sulfide COS, (4) reactive with hydrogen, forming methyl alcohol, CH3OH or methane CH4 in the presence of a catalyzer, (5) reactive with nickel (also iron, cobalt, molybdenum, ruthenium, rhodium, osmium, and iridium) to form nickel carbonyl, Ni(CO)4 (and carbonyls of the other metals named), (6) reactive with fused NaOH, forming sodium formate, HCOONa, (7) reactive with cuprous salt dissolved in either ammonia solution or concentrated HCl, which solutions are utilized in the estimation of carbon monoxide in mixtures of gases, e.g., flue gases of combustion, coal gas, exhaust gases of internal combustion engines, (8) reactive with iodine pentoxide at 150 °C. For the reaction of carbon monoxide with oxygen to form CO2 finely divided iron or palladium wire is used as a catalyzer; for the reaction of carbon monoxide with H2O vapor to form CO2 plus hydrogen (“water gas reaction”) important studies have been made of the conditions; and for the reaction of CO2 plus carbon (hot) similar important studies have been made (at 675 °C, 50% CO2 plus 50% CO; at 900°C, 5% CO2 plus 95% CO). The reaction of carbon plus oxygen at such a temperature as produces carbon monoxide (say 900 °C, 95% CO plus 5% CO2) and evolves heat; while the reaction of carbon plus CO2, producing carbon monoxide at the same temperature absorbs heat. Accordingly it is possible to arrange the oxygen (free or as air) and CO2 supply ratio in such a way that the desired temperature may be continuously maintained. The reduction of CO2 by iron forms carbon monoxide plus ferrous oxide.

General Description

A colorless cryogenic liquid. Prolonged exposure to carbon monoxide rich atmospheres may be fatal. Contact with the liquid can cause severe frostbite. Less dense than air. Easily ignited and a flame can flash back to the source of a leak very easily. Burns with a violet flame. Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. CARBON MONOXIDE is used in organic synthesis, metallurgy, and a fuel.

Air & Water Reactions

Highly flammable.

Reactivity Profile

Contact of very cold liquefied gas with water may result in vigorous or violent boiling and extremely rapid vaporization. If the water is hot, a liquid "superheat" explosion may occur. Pressures may build to dangerous levels if the liquid contacts water in a closed container [Handling Chemicals Safely 1980]. Reacts explosively with bromine trifluoride at high temperatures or concentrations [Mellor 2, Supp. 1:166 1956]. The same is true for various oxidizers such as: chlorine dioxide, oxygen (liquid), peroxodisulfuryl difluoride. Reacts with lithium to give lithium carbonyl, which detonates violently with water, igniting the gaseous products [Mellor 2, Supp 2:84 1961]. Potassium and sodium metals behave similarly. Cesium oxide, iron(III) oxide, and silver oxide all react, in the presence of moisture, at ambient temperatures with carbon monoxide causing ignition, [Mellor, 1941, vol. 2, 487].

Hazard

Highly flammable, dangerous fire and explosion risk. Flammable limits in air 12–75% by volume. Toxic by inhalation. Note: Carbon monox- ide has an affinity for blood hemoglobin over 200 times that of oxygen. A major air pollutant.

Health Hazard

Carbon monoxide is a highly poisonous gas.The acute toxic symptoms include headache,tachypnea, nausea, dizziness, weakness, con fusion, depression, hallucination, loss ofmuscular control, and an increase and thena decrease in pulse and respiratory rate. Ifthe dose is high, these symptoms progressto collapse, unconsciousness, and death.The severity of toxic effects depends on theconcentration of carbon monoxide and theduration of exposure. Prolonged exposure toa concentration of 50 ppm does not resultin adverse health effects in humans, but a6-hour exposure to 100 ppm may produceperceptible effects. A 10-minute exposure to5000 ppm is lethal to humans
LC50 value, inhalation (rats): 1800 ppm/4 h
The biochemical action of carbon monox ide involves its reaction with hemoglobin(Hb) in the blood. It enters into thebloodstream through the lungs and com bines with hemoglobin to form carboxyhe moglobin (COHb). Hemoglobin is essentialfor the transportation of oxygen into the tis sues. The affinity of carbon monoxide tocombine with hemoglobin is about 300 timesgreater than that of oxygen (Meyer 1989).Thus, the CO molecule readily displaces oxy gen from the oxyhemoglobin (O2Hb) to formthe more stable adduct, carboxyhemoglobin
Thus the hemoglobin is tied up. It cannot,therefore, supply oxygen to the tissues, thusresulting in hypoxia and death
Therapy involves artificial respirationusing a compression chamber at about 2atmospheres of oxygen, or a 95% O2/5%CO2 mixture, thus supplying more oxygento compete for the hemoglobin and increasethe solubility of oxygen in the blood plasma.

Fire Hazard

EXTREMELY FLAMMABLE. May be ignited by heat, sparks or flames. Flame may be invisible. Containers may explode when heated. Vapor explosion and poison hazard indoors, outdoors or in sewers. Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Runoff may create fire or explosion hazard.

Flammability and Explosibility

Carbon monoxide is a flammable gas. It forms explosive mixtures with air in the range of 12.5 to 74% by volume.

Industrial uses

Carbon monoxide (CO) is a product of incompletecombustion, and is very reactive. It is oneof the desirable products in synthesis gas formaking chemicals; the synthesis gas made fromcoal contains at least 37% CO. It is also recoveredfrom top-blown O2 furnaces in steel mills.It reacts with H2 to form methanol, which is then catalyzed by zeolites into gasoline. Aceticacid is made by methanol carbonylation, andacrylic acid results from the reaction of CO,acetylene, and methanol.

Materials Uses

Steel and other common metals are satisfactory for use with dry, sulfur-free carbon monoxide at pressures up to 2000 psig (13 790 kPa). Iron, nickel, and other metals can react with carbon monoxide at elevated pressures to form carbonyls in small quantities. The presence of moisture and sulfur-containing impurities in carbon monoxide appreciably increases its corrosive action on steel at any pressure. High-pressure plant equipment is often lined with copper for increased resistance to carbon monoxide attack. Very highly alloyed chrome steels are sufficiently resistant to corrosion by carbon monoxide containing small amounts of sulfur-bearing impurities. Users are strongly urged to make stress corrosion tests of samples of proposed construction materials in order to select one that will withstand the high-pressure use of carbon monoxide under actual conditions.

Safety Profile

Mddly toxic by inhalation in humans but has caused many fatalities. Experimental teratogenic and reproductive effects. Human systemic effects by inhalation: changes in psychophysiological tests and methemoglobinemiacarboxyhemoglobinemia. Can cause asphyxiation by preventing hemoglobin from bindmg oxygen. After removal from exposure, the half-life of elimination from the blood is one hour. Chronic exposure effects can occur at lower concentrations. A common air contaminant. Acute cases of poisoning resulting from brief exposures to hgh concentrations seldom result in any permanent dtsability if recovery takes place. Chronic effects as the result of repeated exposure to lower concentrations have been described, particularly in the Scandinavian literature. Auditory disturbances and contraction of the visual fields have been demonstrated. Glycosuria does occur, and heart irregularities have been reported. Other workers have found that where the poisoning has been relatively long and severe, cerebral congestion and edema may occur, resulting in long-lasting mental or nervous damage. Repeated exposure to low concentration of the gas, up to 100 ppm in air, is generally believed to cause no signs of poisoning or permanent damage. Industrially, sequelae are rare, as exposure, though often severe, is usually brief. It is a common air contaminant. flame. Severe explosion hazard when exposed to heat or flame. Violent or explosive reaction on contact with bromine trifluoride, bromine pentafluoride, chlorine doxide, or peroxodsulfuryl difluoride. Mixture of liquid CO with liquid O2 is explosive. Reacts with sodurn or potassium to form explosive products sensitive to shock, heat, or contact with water. Murture , , . with copper powder + copper(Ⅱ) perchlorate + water forms an explosive complex. dime of liquid CO with liquid dinitrogen oxide is a rocket propellant combination. Ignites on warming with iodine heptafluoride. Ignites on contact with . cesium oxide + water. Potentially explosive reaction with iron(IⅡ) oxide between 0' and 150℃. Exothermic reaction with CIF3, (Li + H2O), NF3,OF2, (K + 04, Ag2O, (Na + NH3). To fight fire, stop flow of gas. A dangerous fire hazard when exposed to

Potential Exposure

Carbon monoxide is used in metallurgy as a reducing agent, particularly in the Mond process for nickel; in organic synthesis, especially in the Fischer
Tropsch process for petroleum products, and in the oxo reaction; and in the manufacture of metal carbonyls. It is usually encountered in industry as a waste product of incomplete combustion of carbonaceous material (complete combustion produces CO2). The major source of CO emission in the atmosphere is the gasoline-powered internal combustion engine. Special industrial processes which contribute significantly to CO emission are iron foundries, particularly the cupola; fluid catalytic crackers; fluid coking; and moving-bed catalytic crackers in thermal operations in carbon black plants; beehive coke ovens; basic oxygen furnaces, sintering of blast furnace feed in steel mills; and formaldehyde manufacture. There are numerous other operations in which a flame touches a surface that is cooler than the ignition temperature of the gaseous part of the flame where exposure to CO may occur,e.g., arc welding, automobile repair; traffic control; tunnel construction; firefighting; mines, use of explosives, etc.

Physiological effects

Carbon monoxide is a chemical asphyxiant and acts toxically by combining with the hemoglobin of the red blood cells to form the stable compound carbon monoxide-hemoglobin. It thus prevents the hemoglobin from taking up oxygen, thereby depriving the body of the oxygen needed for metabolic respiration. The affinity of carbon monoxide for hemoglobin is about 300 times the affinity of oxygen for hemoglobin. The inhalation of concentrations as low as 0.04 percent will result in headache and discomfort within 2 to 3 hours. Inhalation of a 0.4 percent concentration in air proves fatal in less than I hour. Lacking odor and color, carbon monoxide gives no warning of its presence, and inhalation of heavy concentrations can cause sudden unexpected collapse.

First aid

Gas: Move victim to fresh air. Call emergencymedical care. Apply artificial respiration if victim is notbreathing. Do not use mouth-to-mouth method if victimingested or inhaled the substance; induce artificial respiration with the aid of a pocket mask equipped with a one-wayvalve or other proper respiratory medical device.Administer oxygen if breathing is difficult. Remove andisolate contaminated clothing and shoes. In case of contactwith substance, immediately flush skin or eyes with runningwater for at least 20 min. In case of contact with liquefiedgas, thaw frosted parts with lukewarm water. Keep victimwarm and quiet. Keep victim under observation for24-48 h. Effects of contact or inhalation may be delayed.Ensure that medical personnel are aware of the material(s)involved and take precautions to protect themselves.Refrigerated liquid: Move victims to fresh air. Call emergency medical care. Apply artificial respiration if victim isnot breathing. Administer oxygen if breathing is difficult.Remove and isolate contaminated clothing and shoes. Incase of contact with substance, immediately flush skin oreyes with running water for at least 20 min. In case of contact with liquefied gas, thaw frosted parts with lukewarmwater. Keep victim warm and quiet. Keep victim underobservation. Effects of contact or inhalation may be delayed.Ensure that medical personnel are aware of the material(s)involved and take precautions to protect themselves.

Environmental Fate

CO has varied effects on multiple enzymatic reactions and processes. Most easily seen and measured via co-oximetry is its high affinity and binding to Hb. This results in an overall lack of oxygen carrying capacity along with a shift of the oxygen dissociation curve to the left so that even available oxyhemoglobin is less able to offload oxygen to tissue sites. This,coupled with CO’s ability to bind to and arrest cellular metabolism, results in global hypoxemia. The overall lack of tissue perfusion and energy production results in metabolic lactic acidosis.
CO also has the ability to bind to other globins, most importantly myoglobin. Significant myoglobin binding results in lack of tissue oxygenation to heart and myocardial damage.
The final high-risk organ system affected after CO exposure is the central nervous system. CO has the ability to cause delayed neuropsychiatric sequelae in addition to the acute effects seen as a result of hypoxemia. This is thought to be due to delayed lipid peroxidation achieved through the displacement of nitric oxide. A reperfusion-like injury occurs in these cases.

storage

cylinders of carbon monoxide should be stored and used in a continuously ventilated gas cabinet or fume hood. Local fire codes should be reviewed for limitations on quantity and storage requirements.

Shipping

UN1016 Carbon monoxide, compressed, Hazard class: 2.3; Labels: 2.3-Poisonous gas; 2.1- Flammable gas, Inhalation Hazard Zone D. NA9202 Carbon monoxide, refrigerated liquid (cryogenic liquid), Hazard class: 2.3; Labels: 2.3-Poisonous gas; 2.1- Flammable gas, Domestic (United States), Inhalation Hazard Zone D. Cylinders must be transported in a secureupright 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.

Purification Methods

Iron carbonyl is a likely impurity in CO stored under pressure in steel tanks. It can be decomposed by passing the gas through a hot porcelain tube at 350-400o. Passage through alkaline pyrogallol solution removes oxygen (and CO2). Removal of CO2 and water are effected by passage through soda-lime followed by Mg(ClO4)2 or P2O5 and collected over Hg. Carbon monoxide can be condensed and distilled at -195o. It is sparingly soluble in H2O but is readily absorbed by a solution of CuCl in HCl to give the white crystalline adduct CuCl.CO.2H2O. It burns in air with a bright blue flame but a mixture of 2volumes of CO and 1volume of O2 explode when kindled, although in a small jar the combustion is not violent. HIGHLY POISONOUS gas as it reacts with haemoglobin to form bright red carboxyhaemoglobin which is stable and not readily decomposed by oxygen. [Gilliland & Blanchard Inorg Synth II 81 1946, Glemser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 645-646 1963.]

Toxicity evaluation

Exposure to this colorless, odorless gas occurs primarily though inhalation. CO exposure associated with the paint stripper methylene chloride is unique in that methylene chloride is biologically metabolized toCOin vivo. Dermal, oral, and inhalation exposure to methylene chloride can cause CO poisoning.
Aside from tobacco smoke, the most important sources of CO exposure for most individuals are the emissions created by internal combustion engines of vehicles and in household and occupational locations where combustion occurs. Specific sources of exposure include the burning of wood, charcoal, natural gas, or propane for heating and cooking, and propane-powered indoor equipment such as forklifts and ice rink resurfacers.
Average levels of CO in homes without gas stoves vary from 0.5 to 5 ppm. Levels near properly adjusted gas stoves are often 5–15 ppm, and those near poorly adjusted stoves may be 30 ppm or higher. CO exposures occur in a variety of occupational settings. The number of persons occupationally exposed to CO in the working environment is greater than for any other physical or chemical agent. The smoke of a cigarette contains approximately 14 mg of CO. The smoke of cigars ranges from approximately 38 mg for little cigars to almost 100 mg for large and premium cigars. CO in secondhand tobacco smoke has led to levels of CO as high as 50 ppm.

Incompatibilities

Forms extremely explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. In the presence of finely dispersed metal powders the substance forms toxic and flammable carbonyls. May react vigorously with oxygen, acetylene, chlorine, fluorine, nitrous oxide.

Waste Disposal

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. Carbon monoxide can also be recovered from gas mixtures as an alternative to disposal.

Precautions

Carbon monoxide poisoning, prevention, occupational safety Install a CO alarm on each level of your home. Home heating systems, chimneys, and fl ues must be inspected and cleaned by a qualifi ed technician every year. Keep chimneys clear of bird and squirrel nests, leaves, and residue to ensure proper ventilation. Make sure that the furnace and other appliances, such as gas ovens, ranges, and cooktops are inspected for adequate ventilation. Do not burn charcoal inside the house even in the fi replace. Do not operate gasoline-powered engines in confi ned areas, such as garages or basements. Do not leave your car, mower, or other vehicle running in an attached garage, even with the door open. Do not block or seal shut exhaust fl ues or ducts for appliances such as water heaters, ranges, and clothes dryers.

GRADES AVAILABLE

Carbon monoxide is available for commercial and industrial use in various grades of purity ranging from a minimum 98 percent to 99.99 percent.