124-38-9 Usage
Uses
Different sources of media describe the Uses of 124-38-9 differently. You can refer to the following data:
1. Solid carbon dioxide is used quite extensively to refrigerate dairy products, meat products, frozen foods, and other perishable foods while in transit. It is also used as a cooling agent in many industrial processes, such as grinding heat-sensitive materials, rubber tumbling, cold-treating metals, shrink fitting of machinery parts, vacuum cold traps, and so on. Gaseous carbon dioxide is used to carbonate soft drinks, for pH control in water treatment, in chemical processing, as a food preservative, as an inert blanket in chemical and food processing and metal welding, as a growth stimulant for plant life, for hardening molds and cores in foundries, and in pneumatic devices. Liquid carbon dioxide is used as an expendable refrigerant for freezing and chilling food products; for low-temperature testing of aviation, missile, and electronic components; for stimulation of oil and gas wells; for rubber tumbling; and for controlling chemical reactions. Liquid carbon dioxide is also used as a fire extinguishing agent in portable and built-in fire extinguishing systems.
2. Carbon dioxide (CO2) is the 18th most frequently produced chemical in the United States.
It has numerous uses, including in refrigeration, in the manufacture of carbonated drinks
(e.g., soda pop), in fire extinguishers, in providing an inert atmosphere (unreactive environment),
and as a moderator for some types of nuclear reactors.
3. Carbon Dioxide is a gas obtained during fermentation of glucose
(grain sugar) to ethyl alcohol. it is used in pressure-packed foods as
a propellant or aerating agent and is also used in the carbonation of
beverages. it is released as a result of the acid carbonate reaction of
leavening agents in baked goods to produce an increase in volume.
as a solid, it is termed dry ice and is used for freezing and chilling.
4. Carbon dioxide has several major uses: Solid carbon dioxide, dry ice, is used as a refrigerant. Another major use of carbon dioxide is in the soda industry. Soda is sodium carbonate monohydrate (Na2CO3? H2O). Other forms of soda include washing soda, which is sodium carbonate decahydrate (Na2CO3? 10H2O), and baking soda, which is sodium bicarbonate (NaHCO3).Carbon dioxide is used as a gas in fire extinguishers, as an inflation gas for flotation devices, and as a propellant (for example in air guns). In recent years, the use of carbon dioxide as a supercritical fluid in green chemistry applications has increased. A supercritical fluid is a fluid with a temperature and pressure above its critical point.
5. In the carbonation of beverages; manufacture of carbonates; in fire prevention and extinction; for inerting flammable materials during manufacture, handling and transfer; as propellant in aerosols; as dry ice for refrigeration; to produce harmless smoke or fumes on stage; as rice fumigant; as antiseptic in bacteriology and in the frozen food industry. Supercritical or liquid CO2 used in extraction of caffeine and hops aroma; dry cleaning; metal degreasing; cleaning semiconductor chips; paint spraying; polymer modification. Environmentally benign alternative to potentially hazardous solvents in organic and polymer chemistry.
Chemical Properties
Different sources of media describe the Chemical Properties of 124-38-9 differently. You can refer to the following data:
1. Carbon dioxide,CO2, also known as carbonic anhydride and carbonic acid gas, is a colorless,odorless gas that liquifies at -65 °C(-86 OF) and solidifies in dry ice at -78.2 °C(-107 OF). It is soluble in water,alcohol, and most alkaline solutions. In a relatively slow reaction,carbon dioxide hydrates in water to become carbonic acid and is corrosive. In petroleum production, the velocity of the carbon dioxide gas can increase the corrosion rate to very high levels,with the presence of salts becoming unimportant. Carbon dioxide is used in preparing carbonated beverages, fire extinguishers, dry ice refrigerants,and as a raw material in the production of sodium carbonate and sodium bicarbonate using the Solvay procedure.
2. Carbon dioxide is a colorless, odorless, noncombustible gas.
3. Carbon dioxide occurs naturally as approximately 0.03% v/v of the
atmosphere. It is a colorless, odorless, noncombustible gas with a
faint acid taste. Solid carbon dioxide, also known as dry ice, is
usually encountered as white-colored pellets or blocks.
Physical properties
Colorless, odorless and tasteless gas; 1.53 times heavier than air; density 1.80 g/L at 25°C; can be liquefied under pressure; liquefies at -56.6°C at 5.2 atm; density of liquid CO2 at 0°C and 34 atm 0.914 g/mL; solidifies to white snow-like flakes known as dry ice, density 1.56 g/cm3 at -79°C; dry ice sub limes to CO2 gas at -78.5°C; critical temperature 31°C; critical pressure 72.79 atm, critical density 94 cm3/mol; moderately soluble in water, solubility 173 mL and 88mL CO2/100 mL water at 0°C and 20°C, respectively; solubility increases with pressure.
Occurrence
Carbon dioxide is found throughout nature. Its concentration in the air is 0.036% by volume. It is the primary component of exhaled air of all animals. It also is the product of oxidation of all carbonaceous matter and an end prod?uct of complete combustion. It also is found dissolved in natural waters. It occurs in the earth’s crust and in volcanic eruptions. All plants depend on carbon dioxide and water for their survival, making their food by the process of photosynthesis. Carbon dioxide is found in abun?dance in the atmospheres of many other planets and their moons throughout the solar system. Carbon dioxide is a greenhouse gas, which traps the infrared radiation re?radiated back by the earth’s surface, causing global warming and, therefore, changing the climate. The CO2 concentration in the atmosphere over a 30- year period from 1960 to 1990 has increased significantly from about 320 to 356 ppm by volume, which is widely attributed to the growth of industrial and automobile CO2 emission during this period. Carbon dioxide has extensive commercial applications. Some important applications of this compound include carbonation of beverages; as a fire extinguishing agent; in the manufacture of carbonates; as dry ice (solid CO2) for refrigeration; as an aerosol propellant; as a shielding gas for welding; as an inert atmosphere in preparation and handling of flammable substances; in cloud seeding; in fumigation of rice; to produce harmless smoke on stage; as an antiseptic; and as a supercritical fluid to extract organic pollutants for their analyses.
History
The discovery of carbon dioxide, credited to Joseph Black (1728–1799), played a critical role in supplanting the phlogiston theory and advancing the development of modern chemistry. Black, in his medical studies, was searching for a substance to dissolve kidney stones, but he switched his subject to a study of stomach acidity. Black was working with the carbonates magnesia alba (magnesium carbonate) and calcium carbonate (limestone) and observed that when magnesia alba was heated or reacted with acids, it produced a gas and a salt. Black, who published his work in 1756, called the gas “fixed air” and noted that it had properties similar to those described by Jan Baptista van Helmont (1577–1644) for spiritus sylvestrius. Spiritus sylvestrius was the gas produced during combustion processes, and van Helmont realized that this was the same gas produced during fermentation and when acids reacted with seashells.
Definition
Different sources of media describe the Definition of 124-38-9 differently. You can refer to the following data:
1. ChEBI: A one-carbon compound with formula CO2 in which the carbon is attached to each oxygen atom by a double bond. A colourless, odourless gas under normal conditions, it is produced during respiration by all animals, fungi and microorganism
that depend directly or indirectly on living or decaying plants for food.
2. 1. The
solution of carbon dioxide in a liquid
under pressure, as in carbonated soft
drinks.
2. The addition of carbon dioxide to compounds,
e.g. the insertion of carbon dioxide
into Grignard reagents.
3. carbon dioxide: A colourlessodourless gas, CO2, soluble in water,ethanol, and acetone; d. 1.977 g dm–3(0°C); m.p. –56.6°C; b.p. –78.5°C. It occursin the atmosphere (0.04% by volume)but has a short residence timein this phase as it is both consumedby plants during photosynthesis andproduced by respiration and by combustion.It is readily prepared in thelaboratory by the action of diluteacids on metal carbonates or of heaton heavy-metal carbonates. Carbondioxide is a by-product from themanufacture of lime and from fermentationprocesses.Carbon dioxide has a small liquidrange and liquid carbon dioxide isproduced only at high pressures. Themolecule CO2 is linear with each oxygenmaking a double bond to the carbon.Chemically, it is unreactive andwill not support combustion. It dissolves in water to give carbonicacid.Large quantities of solid carbondioxide (dry ice) are used in processesrequiring large-scale refrigeration. Itis also used in fire extinguishers as adesirable alternative to water formost fires, and as a constituent ofmedical gases as it promotes exhalation.It is also used in carbonateddrinks.The level of carbon dioxide in theatmosphere has increased by some12% in the last 100 years, mainly becauseof extensive burning of fossilfuels and the destruction of largeareas of rain forest. This has beenpostulated as the main cause of theaverage increase of 0.5°C in globaltemperatures over the same period,through the greenhouse effect.Steps are now being taken to preventfurther increases in atmospheric CO2concentration and subsequent globalwarming.
Preparation
Carbon dioxide is produced as a by-product in many processes. It is pro duced as a by-product in the manufacture of lime from calcium carbonate:
CaCO3 →CaO + CO2
CO2 also is derived from synthesis gas which is a mixture of CO, CO2, H2 and N2 from air obtained by steam reforming. Carbon dioxide also is obtained by combustion of natural gas:
CH4 + 2O2 → CO2 + 2H2O
It also is obtained as a by-product in the Haber-Bosch process for the man ufacture of ammonia. The method involves passing steam and air over hot coke.
Carbon dioxide also is produced along with ethanol from fermentation of carbohydrates by yeast:
C6H12O6→2CO2 + 2C2H5OH
In the laboratory, CO2 may be produced by the reaction of any carbonate with a dilute mineral acid:
CaCO3 + 2HCl → CaCl2 + CO2 + H2O
Production Methods
Different sources of media describe the Production Methods of 124-38-9 differently. You can refer to the following data:
1. Carbon dioxide is obtained industrially in large quantities as a byproduct
in the manufacture of lime; by the incineration of coke or
other carbonaceous material; and by the fermentation of glucose by
yeast. In the laboratory it may be prepared by dropping acid on a
carbonate.
2. Carbon dioxide accounts for 0.037% by volume of the atmosphere.Several methods can be used to produce large volumes of CO2. The combustion of coke or other carbonaceous substances produces results in CO2: C(coke) + O2 → CO2(g). In combustion processes, CO2 is concentrated by separating it from other gases using scrubbing and absorption techniques. Another source of CO2 involves the calcination (slow heating) of carbonates such as limestone, CaCO3: CaCO3(s)→ CaO + CO2(g).This process takes place in a lime kiln in the production of precipitated calcium carbonate at temperatures of from 500°C to 900°C. Carbon dioxide is also produced as a by-product in fermentation reactions to produce alcohols. An example is the fermentation of glucose, C6H12O6 to ethanol (C2H5OH): C6H12O6(aq)→ 2C2H5OH(aq) + 2CO2(g). Carbon dioxide is produced as a by-product in a number of syntheses, such as the Haber process, to produce ammonia.
General Description
An odorless, white solid. Can cause damaging frostbite. Noncombustible and nontoxic. Liquefies at -109°F. Can asphyxiate by displacement of air. Used as a refrigerant.
Air & Water Reactions
Water soluble. Forms carbonic acid, a mild acid in water.
Reactivity Profile
Contact of very cold liquid/solid carbon dioxide 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. With water forms weak carbonic acid in nonhazardous reaction. Dusts of magnesium, lithium, potassium, sodium, zirconium, titanium, and some magnesium-aluminum alloys, and heated aluminum, chromium, and magnesium when suspended in carbon dioxide are ignitable and explosive. This is especially true in the presence of strong oxidizers, such as peroxides. The presence of carbon dioxide in solutions of aluminum hydride in ether can cause violent decomposition on warming the residue, [J. Amer. Chem. Soc., 1948, 70, 877]. Dangers arising from the use of carbon dioxide in the fire prevention and extinguishing systems of confined volumes of air and flammable vapors are examined. The hazard associated with its use centers around the fact that large electrostatic discharges may be created that initiate explosion, [Quart. Saf. Summ., 1973, 44(1740, 10].
Hazard
Solid damaging to skin and tissue; keep
away from mouth and eyes. Asphyxia.
Health Hazard
Different sources of media describe the Health Hazard of 124-38-9 differently. You can refer to the following data:
1. Vapors may cause dizziness or asphyxiation without warning. Vapors from liquefied gas are initially heavier than air and spread along ground. Contact with gas or liquefied gas may cause burns, severe injury and/or frostbite.
2. Carbon dioxide is an asphyxiant. Exposureto about 9–10% concentration can causeunconsciousness in 5 minutes. Inhalation of3% CO2 can produce weak narcotic effects.Exposure to 2% concentration for severalhours can produce headache, increased bloodpressure, and deep respiration.
Fire Hazard
Non-flammable gases. Containers may explode when heated. Ruptured cylinders may rocket.
Agricultural Uses
Different sources of media describe the Agricultural Uses of 124-38-9 differently. You can refer to the following data:
1. Carbon dioxide (CO2) is a compound of two oxygen
atoms covalently bonded to a carbon atom. It is a
colorless, odorless, tasteless gas, soluble in water,
ethanol and acetone, and is 15 times heavier than air.
Carbon dioxide occurs in the earth's atmosphere at an
average of 0.04% by volume. The volume keeps changing,
as it is consumed by plants during photosynthesis and
replenished during respiration and combustion of
biomass. CO2 is a major source of carbon for plants.
Carbon dioxide is readily prepared in a laboratory by
the action of dilute acids on carbonates. It is also obtained
as a by-product from the manufacture of lime and from
fermentation processes. Chemically, CO2 is not reactive
and does not support combustion. It gives carbonic acid
on dissolution in water.
Carbon dioxide is one of the key materials for urea
production. Liquid carbon dioxide is produced at high
pressures and has a small liquid range. Solid carbon
dioxide (known as dry ice), produced by subjecting
gaseous carbon dioxide to pressure and temperature, is
used in refrigeration, carbonated drinks and fire
extinguishers. It is also a constituent of medical
treatment, as it promotes exhalation.
The level of carbon dioxide in the atmosphere has
increased by 12% in the last 100 years, mainly due to the
burning of fossil fuels and the destruction of rain forests.
The increased level of carbon dioxide is the main cause
for an average increase of 0.5℃ in the mean global
temperature through the greenhouse effect.
Environmentalists urge that measures be taken to prevent
any further increase in atmospheric carbon dioxide, and the
subsequent global warming and melting of ice caps.
In calcareous soils, the partial pressure of carbon
dioxide in the soil air influences its pH; it is 8.5 when free
calcium carbonate in the soil is in equilibrium with
atmospheric carbon dioxide. An increase in carbon
dioxide in the soil air decreases the pH to around 7.3.
Applications of carbon dioxide include its use as (a) a
refrigerant in either solid or liquid form, (b) an inert
medium, (c) a chemical reactant, (d) a neutralizing agent
for alkalis, (e) a pressurizing agent, and ( f ) an ingredient
in the manufacture of aerated water.
2. Solid carbon dioxide is known as dry ice. It is produced by cooling gaseous carbon dioxide under pressure.Dry ice is used in refrigeration, carbonated drinks and fire extinguishers. It is also a constituent of medical gases, as it promotes exhalation.
Pharmaceutical Applications
Carbon dioxide and other compressed gases such as nitrogen and
nitrous oxide are used as propellants for topical pharmaceutical
aerosols. They are also used in other aerosol products that work
satisfactorily with the coarse aerosol spray that is produced with
compressed gases, e.g. cosmetics, furniture polish, and window
cleaners.
The advantages of compressed gases as aerosol propellants are
that they are less expensive; are of low toxicity; and are practically
odorless and tasteless. Also, in comparison to liquefied gases, their
pressures change relatively little with temperature. However, the
disadvantages of compressed gases are that there is no reservoir of
propellant in the aerosol and pressure consequently decreases as the
product is used. This results in a change in spray characteristics.
Additionally, if a product that contains a compressed gas as a
propellant is actuated in an inverted position, the vapor phase,
rather than the liquid phase, is discharged. Most of the propellant is
contained in the vapor phase and therefore some of the propellant
will be lost and the spray characteristics will be altered. Also, sprays
produced using compressed gases are very wet. Valves, such as the
vapor tap or double dip tube, are currently available and will
overcome these problems.
Carbon dioxide is also used to displace air from pharmaceutical
products by sparging and hence to inhibit oxidation. As a food
additive it is used to carbonate beverages and to preserve foods such
as bread from spoilage by mold formation, the gas being injected
into the space between the product and its packaging.
Solid carbon dioxide is also widely used to refrigerate products
temporarily, while liquid carbon dioxide, which can be handled at
temperatures up to 318℃ under high pressure, is used as a solvent
for flavors and fragrances, primarily in the perfumery and food
manufacturing industries.
Safety Profile
An asphpant. See
discussion of simple asphyxiants under
ARGON. Experimental teratogenic and
reproductive effects. Contact of solid
carbon dioxide snow with the skin can cause
burns. Dusts of magnesium, zirconium,
titanium, and some magnesium-aluminum
alloys igmte and then explode in COa
atmospheres. Dusts of aluminum,
chromium, and manganese ignite and then
explode when heated in CO2. Several bulk
metals wlll burn in CO2. Reacts vigorously with (Al + Na2O2), Cs2O, Mg(C2H5)2, Li,
(Mg + Na2O2), K, KHC, Na, Na2C2, NaK,
Ti. CO2 fire extingushers can produce
highly incendiary sparks of 5-1 5 mJ at
10-20 kV by electrostatic discharge.
Incompatible with acrylaldehyde, aziridme,
metal acetylides, sodium peroxide.
Safety
In formulations, carbon dioxide is generally regarded as an
essentially nontoxic material.
Potential Exposure
Gaseous Carbon dioxide is used to
carbonate beverages; as a weak acid in the textile, leather,
and chemical industries; in water treatment; and in the
manufacture of aspirin and white lead; for hardening molds
in foundries; in food preservation, in purging tanks and
pipe lines; as a fire extinguisher, in foams; and in welding.
Because it is relatively inert, it is utilized as a pressure
medium. It is also used as a propellant in aerosols; to promote plant growth in green houses; it is used medically as
a respiratory stimulant; in the manufacture of carbonates;
and to produce an inert atmosphere when an explosive or
flammable hazard exists. The liquid is used in fire extinguishing equipment; in cylinders for inflating life rafts; in
the manufacturing of dry ice, and as a refrigerant. Dry ice
is used primarily as a refrigerant. Occupational exposure to
carbon dioxide may also occur in any place where fermentation processes may deplete oxygen with the formation of
carbon dioxide, e.g., in mines, silos, wells, vats, ships’
holds, etc.
Physiological effects
Carbon dioxide is nonnally present in the atmosphere
at about 0.035 percent by volume. It
is also a nonnal end-product of human and animal
metabolism. The exhaled breath contains up
to 5.6 percent carbon dioxide. The greatest
physiological effect of carbon dioxide is to
stimulate the respiratory center, thereby controlling
the volume and rate of respiration. It is
able to cause dilation and constriction of blood
vessels and is a vital constituent of the acid-base
mechanism that controls the pH of the blood.
Carbon dioxide acts as a stimulant and a depressant
on the central nervous system. Increases
in heart rate and blood pressure have
been noted at a concentration of 7.6 percent,
and dyspnea (labored breathing), headache,
dizziness, and sweating occur if exposure at that
level is prolonged. At concentrations of 10 percent
and above, unconsciousness can result in I
minute or less. Impainnent in perfonnance has
been noted during prolonged exposure to concentrations
of 3 percent carbon dioxide even
when the oxygen concentration was 21 percent.
Environmental Fate
Carbon dioxide is an asphyxiant, means it causes toxicity by
displacing oxygen from the breathing atmosphere primarily in
enclosed spaces or in open spaces due to sudden release of
massive amounts of CO2 (for example, forests fire or natural
emission during a volcanic eruption) and results in hypoxia.
Thehumanbody produces about 12 000–13 000 mmols per day
of CO2 and is excreted primarily via lungs. The CO2 concentration
in plasma is maintained within a narrow range of
40±5 mm Hg (4.7–6 KPa). At plasma concentration of
22.5mmHg (3 KPa) or less death can occur within few minutes.
The cause of death in breathing high concentration ofCO2 is due
to CO2 poisoning, that results in rapid decrease in blood pH
(respiratory acidosis,
Low concentrations of CO2 in the air, or insufficient time for
CO2 in blood to exchange with oxygen (O2) in air such as in the
situations of hyperventilation, can lead to an increase in blood
pH (respiratory alkalosis, >pH 7.45). The reaction of CO2 with
water in the body is catalyzed by the enzyme carbonic anhydrases
(or carbonate dehydratases), which leads to formation of carbonic
acid, followed by dissociation into protons (H+) and bicarbonate
(HCO3-
). Carbonic acid is buffered in the cell primarily
by hemoglobin and proteins, which have limited capacity.
storage
Extremely stable and chemically nonreactive. Store in a tightly
sealed cylinder. Avoid exposure to excessive heat.
Shipping
Carbon dioxide (UN1013, UN2187), Hazard
Class: 2.2; Labels: 2.2-Nonflammable compressed gas. Dry
ice (UN1845), Hazard class 9 is considered a “miscellaneous hazardous material” and does not require a label.
The gas and refrigerated liquid fall in Hazard Class 2.2 and
there is no Packing Group; solid, dry ice falls in Hazard
Class 9. Solid, dry ice carries the symbol “AW.” The letter
“A” restricts the application of requirements of this subchapter to materials offered or intended for transportation
by aircraft, unless the material is a hazardous substance or
a hazardous waste. The letter “W” restricts the application
of requirements of this subchapter to materials offered or
intended for transportation by vessel, unless the material is
a hazardous substance or a hazardous waste. Cylindersmust be transported in a secure upright position, in a wellventilated 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
Pass the gas over CuO wire at 800o to oxidise CO and other reducing impurities (such as H2), then over copper dispersed on Kieselguhr at 180o to remove oxygen. Drying it at -78o removes the water vapour. Final purification is by vacuum distillation at liquid nitrogen temperature to remove non-condensable gases [Anderson et al. J Chem Soc 3498 1962]. Sulfur dioxide contaminant can be removed at 450o using silver wool combined with a plug of platinised quartz wool. Halogens are removed by using Mg, Zn or Cu, heated to 450o. [Glemsner in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 647 1963.]
Toxicity evaluation
The CO2 cycle is part of carbon cycle in the ecosystem. Carbon
dioxide cycles in the environment (atmospheric air and surface
water) through respiration (aerobic and anaerobic), photosynthesis,
decomposition, and release from earth’s carbon sinks
(fossil fuels – coal, petroleum, methane; and calcium carbonate
rocks) during combustion. In water, dissolved CO2 reacts with
calcium to form calcium carbonate and precipitates to the ocean
floor. Few examples of most common reactions in the CO2 and carbon cycles in animals, plants, and the environment are presented
below. Most of these reactions either use or produce
energy.
Incompatibilities
Different sources of media describe the Incompatibilities of 124-38-9 differently. You can refer to the following data:
1. The substance decomposes on heating
above 2000C producing toxic carbon monoxide. Reacts
violently with strong bases and alkali metals. Various metal
dusts from chemically active metals, such as magnesium,
zirconium, titanium, aluminum, chromium, and manganese
are ignitable and explosive when suspended and heated in
carbon dioxide.
2. Carbon dioxide is generally compatible with most materials
although it may react violently with various metal oxides or
reducing metals such as aluminum, magnesium, titanium, and
zirconium. Mixtures with sodium and potassium will explode if
shocked.
Waste Disposal
Return refillable compressed
gas cylinders to supplier. Vent to atmosphere
Regulatory Status
GRAS listed. Accepted for use in Europe as a food additive.
Included in the FDA Inactive Ingredients Database (aerosol
formulation for nasal preparations; IM and IV injections). Included
in the Canadian List of Acceptable Non-medicinal Ingredients.
Check Digit Verification of cas no
The CAS Registry Mumber 124-38-9 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 1,2 and 4 respectively; the second part has 2 digits, 3 and 8 respectively.
Calculate Digit Verification of CAS Registry Number 124-38:
(5*1)+(4*2)+(3*4)+(2*3)+(1*8)=39
39 % 10 = 9
So 124-38-9 is a valid CAS Registry Number.
InChI:InChI=1/C2H2O5/c3-1(4)7-2(5)6/h(H,3,4)(H,5,6)
124-38-9Relevant articles and documents
CO activation pathways and the mechanism of Fischer-Tropsch synthesis
Ojeda, Manuel,Nabar, Rahul,Nilekar, Anand U.,Ishikawa, Akio,Mavrikakis, Manos,Iglesia, Enrique
, p. 287 - 297 (2010)
Unresolved mechanistic details of monomer formation in Fischer-Tropsch synthesis (FTS) and of its oxygen rejection routes are addressed here by combining kinetic and theoretical analyses of elementary steps on representative Fe and Co surfaces saturated w
Reactivity of Silanes with (tBuPONOP)Ruthenium Dichloride: Facile Synthesis of Chloro-Silyl Ruthenium Compounds and Formic Acid Decomposition
Anderson, Nickolas H.,Boncella, James M.,Tondreau, Aaron M.
, p. 13617 - 13622 (2017)
The coordination of tBuPONOP (tBuPONOP=2,6-bis(ditert-butylphosphinito)pyridine) to different ruthenium starting materials, to generate (tBuPONOP)RuCl2, was investigated. The resultant (tBuPONOP)RuCl
Photocatalytic reactions under irradiation of visible light over gold nanoparticles supported on titanium(IV) oxide powder prepared by using a multi-step photodeposition method
Tanaka, Atsuhiro,Sakaguchi, Satoshi,Hashimoto, Keiji,Kominami, Hiroshi
, p. 1931 - 1938 (2014)
Titanium(IV) oxide (TiO2) having both smaller and larger gold (Au) particles was successfully prepared by a multi-step (MS) photodeposition method. When 0.25 wt% Au loading per photodeposition was repeated four times, smaller and larger Au particles having average diameters of 1.4 and 13 nm, respectively, were fixed on TiO2, and the Au/TiO2 sample exhibited strong photoabsorption around 550 nm due to surface plasmon resonance (SPR) of the larger Au particles. Various Au/TiO2 samples were prepared by changing the Au loading per photodeposition and the number of photodepositions. Effects of the conditions in MS photodeposition and sample calcination on Au particle distribution and photoabsorption properties were investigated. These samples were used for hydrogen (H2) formation from 2-propanol and mineralization of acetic acid in aqueous suspensions under irradiation of visible light. In the case of H2 formation under deaerated conditions, the reaction rate of Au/TiO2 having both larger and smaller particles was 4 times higher than that of the Au/TiO2 sample without smaller Au particles, indicating that smaller Au particles acted effectively as a co-catalyst, that is, as reduction sites for H2 evolution. On the other hand, in the case of mineralization of acetic acid under aerated conditions, carbon dioxide formation rates were independent of the presence of smaller Au particles, indicating that the smaller Au particles had little effect on the mineralization of acetic acid. To extend the possibility of Au/TiO2 for H2 formation under irradiation of visible light, H2 formation from ammonia (NH3) as biomass waste was examined under deaerated conditions; NH3 was decomposed to H 2 and nitrogen with a stoichiometric ratio of 3:1. The Royal Society of Chemistry 2014.
Study on the kinetics of thermal decomposition of CaCO3
Wei,Luo
, p. 303 - 310 (1995)
By means of TG, the thermal decomposition of the powdered CaCO3 was tested with its various dispersities, range of size, and the different content of CO2 in flowing nitrogen. Formulae for calculating the rate and time of decomposition were obtained.
Autothermal reforming of CH4 over supported Ni catalysts prepared from Mg-Al hydrotalcite-like anionic clay
Takehira, Katsuomi,Shishido, Tetsuya,Wang, Peng,Kosaka, Tokuhisa,Takaki, Ken
, p. 43 - 54 (2004)
spc-Ni/MgAl (spc: solid-phase crystallization method) catalysts were prepared from Mg-Al hydrotalcite-like compounds containing Ni at the Mg site as the precursors and tested for partial oxidation of CH4 into synthesis gas. The activity of spc-
Synthesis of four-angle star-like CoAl-MMO/BiVO4 p-n heterojunction and its application in photocatalytic desulfurization
Yun, Limin,Yang, Zhanxu,Yu, Zong-Bao,Cai, Tianfeng,Li, Yue,Guo, Changyou,Qi, Chengyuan,Ren, Tieqiang
, p. 25455 - 25460 (2017)
A four-angle star-like Co-Al mixed metal oxide (CoAl-MMO)/BiVO4 heterojunction has been synthesized via a hydrothermal method and following sintering. The CoAl-MMO/BiVO4 is derived from CoAl-LDHs/BiVO4, in which CoAl-LDHs leads to a distribution of amorphous CoAl-MMO. The CoAl-MMO loading on BiVO4 greatly enhances visible light absorption, improves charge separation by band offset charge transfer, and makes flat band potential more negative. The three effects together result in excellent photocatalytic activity. Under visible light irradiation, desulfurization efficiency of thiophene has achieved up to 98.58% on CoAl-MMO/BiVO4 with molar ratio of 0.3:5.
Structure of surface tantalate species and photo-oxidation of carbon monoxide over silica-supported tantalum oxide
Tanaka, Tsunehiro,Nojima, Hiroyuki,Yamamoto, Takashi,Takenaka, Sakae,Funabiki, Takuzo,Yoshida, Satohiro
, p. 5235 - 5239 (1999)
Tantalum oxide (10 wt.% as Ta2O5) supported on silica was prepared and the structure and the photo-oxidation of carbon monoxide over the catalyst sample were investigated. XAFS analysis showed that surface tantalate is a TaO4 tetrahedral species with a Ta=O bond which is a photoactive center. The initiation of the photo-oxidation of carbon monoxide is the photoadsorption of an oxygen molecule on the catalyst sample, elucidated by photoluminescence. EPR spectroscopy showed that the photo-excited center interacts with an oxygen molecule to form a T-type ozonide ion. A carbon monoxide ion attacks the ozonide ion to form an [O3-CO]- paramagnetic intermediate to lead the production of carbon dioxide.
Catalytic properties of γ-Al2O3 supported Pt-FeOx catalysts for complete oxidation of formaldehyde at ambient temperature
Cui, Weiyi,Yuan, Xiaoling,Wu, Ping,Zheng, Bin,Zhang, Wenxiang,Jia, Mingjun
, p. 104330 - 104336 (2015)
A series of γ-Al2O3 supported Pt-FeOx catalysts (Pt-FeOx/Al2O3) with different Fe/Pt atom ratios were prepared, and their catalytic properties were investigated in the oxidation of formaldehyde. It was found that the catalytic activities of Pt-FeOx/Al2O3 catalysts are varied with the change of Fe/Pt ratios. Among them, the sample with a Fe/Pt ratio of 1.0 exhibits the highest activity, which can efficiently convert formaldehyde to CO2 at ambient temperature. The catalytic activity of the Pt-FeOx/Al2O3 catalyst can be further improved by the addition of water vapor into the feed stream. A variety of characterization results showed that both Pt nanoparticles and FeOx species are highly dispersed on the surface of the γ-Al2O3 support. Changing Fe/Pt ratios could influence the chemical states and the redox properties of Pt and Fe species. The catalysts with appropriate Fe/Pt ratios have more accessible active sites, i.e., the Pt-O-Fe species, which are located at the boundaries between FeOx and Pt nanoparticles, thus showing high activity for the oxidation of formaldehyde under ambient conditions.
Purification and characterization of urease from dehusked pigeonpea (Cajanus cajan L) seeds.
Das, Nilanjana,Kayastha, Arvind M,Srivastava, Punit K
, p. 513 - 521 (2002)
Urease has been purified from the dehusked seeds of pigeonpea (Cajanus cajan L.) to apparent electrophoretic homogeneity with approximately 200 fold purification, with a specific activity of 6.24 x10(3) U mg(-1) protein. The enzyme was purified by the sequence of steps, namely, first acetone fractionation, acid step, a second acetone fractionation followed by gel filtration and anion-exchange chromatographies. Single band was observed in both native- and SDS-PAGE. The molecular mass estimated for the native enzyme was 540 kDa whereas subunit values of 90 kDa were determined. Hence, urease is a hexamer of identical subunits. Nickel was observed in the purified enzyme from atomic absorption spectroscopy with approximately 2 nickel ions per enzyme subunit. Both jack bean and soybean ureases are serologically related to pigeonpea urease. The amino acid composition of pigeonpea urease shows high acidic amino acid content. The N-terminal sequence of pigeonpea urease, determined up to the 20th residue, was homologous to that of jack bean and soybean seed ureases. The optimum pH was 7.3 in the pH range 5.0-8.5. Pigeonpea urease shows K(m) for urea of 3.0+/-0.2 mM in 0.05 M Tris-acetate buffer, pH 7.3, at 37 degrees C. The turnover number, k(cat), was observed to be 6.2 x 10(4) s(-1) and k(cat)/K(m) was 2.1 x 10(7) M(-1) s(-1). Pigeonpea urease shows high specificity for its primary substrate urea.
The effect of the particle size on the kinetics of CO electrooxidation on high surface area Pt catalysts
Arenz, Matthias,Mayrhofer, Karl J. J.,Stamenkovic, Vojislav,Blizanac, Berislav B.,Tomoyuki, Tada,Ross, Phil N.,Markovic, Nenad M.
, p. 6819 - 6829 (2005)
Using high-resolution transmission electron microscopy (TEM), infrared reflection-absorption spectroscopy (IRAS), and electrochemical (EC) measurements, platinum nanoparticles ranging in size from 1 to 30 nm are characterized and their catalytic activity for CO electrooxidation is evaluated. TEM analysis reveals that Pt crystallites are not perfect cubooctahedrons, and that large particles have rougher surfaces than small particles, which have some fairly smooth (111) facets. The importance of defect sites for the catalytic properties of nanoparticles is probed in IRAS experiments by monitoring how the vibrational frequencies of atop CO (νCO) as well as the concomitant development of dissolved CO 2 are affected by the number of defects on the Pt nanoparticles. It is found that defects play a significant role in CO clustering on nanoparticles, causing CO to decrease/increase in local coverage, which yields to anomalous redshift/ blueshift νCO frequency deviations from the normal Stark-tuning behavior. The observed deviations are accompanied by CO2 production, which increases by increasing the number of defects on the nanoparticles, that is, 1 ≤ 2 ad on defect sites rather than by CO energetics. These results are complemented by chronoamperometric and rotating disk electrode (RDE) data. In contrast to CO stripping experiments, we found that in the backsweep of CO bulk oxidation, the activity increases with decreasing particle size, that is, with increasing oxophilicity of the particles.