SYNTHESIS OF CHEMICALS FROM CARBON DIOXIDE:Carbon dioxide - Dry Ice

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Chapter - 14

SYNTHESIS OF CHEMICALS FROM CARBON DIOXIDE

T. M. Sankaranarayanan

INTRODUCTION

Carbon dioxide is an atmospheric gas contains one carbon and two oxygen atoms. It is

well known chemical compound and its chemical formula CO2. Dry ice is nothing but

solid-state carbon dioxide. It was one of the first gases to be described as a substance

distinct from air.

In the 17th century, the Flemish chemist Jan Baptist van Helmont observed that when

he burnt charcoal in a closed vessel, the mass of the resulting ash was much less than that

of the original charcoal. His interpretation was that the rest of the charcoal had been

transmuted into an invisible substance he termed a "gas" or "wild spirit" (spiritus

sylvestre). The Scottish physician Joseph Black studied some of the properties more

thoroughly in the 1750's. He found that limestone (calcium carbonate) could be heated or

treated with acids to yield a gas as he termed "fixed air." He observed that the fixed air

was denser than air and did not support either flame or animal life. He also found that it

would, when bubbled through an aqueous solution of lime (calcium hydroxide),

precipitate calcium carbonate, and used this phenomenon to demonstrate that carbon

dioxide is produced by animal respiration and microbial fermentation. In 1772, Joseph

Priestley used carbon dioxide produced from the action of sulfuric acid on limestone to

prepare soda water, the first known instance of an artificially carbonated beverage. CO2

was first liquefied (at elevated pressures) in 1823 by Humphrey Davy and Michael

Faraday. The earliest description of solid carbon dioxide was given by Charles Thilorier,

who in 1834 opened a pressurized container of liquid carbon dioxide, only to find that the

cooling produced by the rapid evaporation of the liquid yielded a "snow" of solid CO2.

Most of the combustion of organic matter, volcanic out gassing and respiration

processes of living aerobic organisms are the main sources of the carbon dioxide. Various

microorganisms from fermentation and cellular respiration also produce it. During the

photosynthesis plants take in the carbon dioxide and using both the carbon and oxygen to

form carbohydrates. In addition, plants also release oxygen to the atmosphere, which is

subsequently used for respiration by heterotrophic organisms, forming a cycle. It is

14.2

Synthesis of Chemicals from Carbon dioxide

present in the earth's atmosphere at a low concentration and acts as a greenhouse gas. It

is a major component of the cycle.

Green house effect is nothing but an increase in the absorption of radiation energy from

sun caused by the existence of gases in the earth atmosphere. Because of this absorption

the earth atmospheric temperature is raising which is called "global warming". Some of

the gases like CO2, CH4, O3, CFCs and H2O vapors are called "green house gases".

Mainly these gases are responsible for this absorption. CO2 being an important member

of these gases is responsible for many climatic changes demonstrating the importance of

CO2 content in atmosphere. Because of mounting of Industrial Revolution, the Percentage

of carbon dioxide in the earth atmosphere is increasing virtually at the rate of 1% per

annum; from 250ppm of the pre-industrial period to a present level of 400ppm (315ppm

in 1958, 340ppm in1984). Because of this global warming the snow cover in the northern

hemisphere and floating ice in the artic ocean have decreased considerably. Moreover,

globally sea water level increased up to 8 inches in the last decade. There is an increase in

worldwide precipitation by one percent. There is abnormal rainfall through out the world.

Unfortunately, greenhouse gases are likely to increase the rate of climate changes.

CARBON DIOXIDE - CHEMICAL AND PHYSICAL PROPERTIES

1) Carbon dioxide is a colorless gas.

2) When inhaled at high concentrations (a dangerous activity because of the

associated asphyxiation risk), it produces a sour taste in the mouth and a stinging

sensation in the nose and throat.

3) These kind of effects result from the gas dissolving in the mucous membranes

and saliva, forming a weak solution of carbonic acid.

4) Its density at 25 °C is 1.98 kg m-3, about 1.5 times that of air.

5) It has no electrical dipole. As it is fully oxidized, it is not very reactive and, in

particular, not flammable.

6) At temperatures below -78 °C, carbon dioxide condenses into a white solid called

dry ice. Liquid carbon dioxide forms only at pressures above 5.1 atm; at

atmospheric pressure, it passes directly between the gaseous and solid phases in a

process called sublimation.

Synthetic Strategies in Chemistry

14.3

7) Water will absorb its own volume of carbon dioxide, and more than this under

pressure. About 1% of the dissolved carbon dioxide turns into carbonic acid. The

carbonic acid in turn dissociates partly to form bicarbonate and carbonate ions.

Test for Carbon dioxide

When a lighted splint is inserted into a test tube containing carbon dioxide, the flame is

immediately extinguished, as carbon dioxide does not support combustion. (Certain fire

extinguishers contain carbon dioxide to extinguish the flame). To further confirm that the

gas is carbon dioxide, the gas may be bubbled into calcium hydroxide solution. The

calcium hydroxide turns milky because of the formation of calcium carbonate.

Applications

1) Liquid and solid carbon dioxide are important refrigerants, especially in the food

industry, where they are employed during the transportation and storage of ice

cream and other frozen foods. Solid carbon dioxide is called "dry ice" and is used

for small shipments where refrigeration equipment is not practical.

2) Carbon dioxide is used to produce carbonated soft drinks and soda water.

Traditionally, the carbonation in beer and sparkling wine come about through

natural fermentation, but some manufacturers carbonate these beverages

artificially.

3) The leavening agents used in baking produce carbon dioxide to cause dough to

rise. Baker's yeast produces carbon dioxide by fermentation within the dough,

while chemical leaveners such as baking powder and baking soda release carbon

dioxide when heated or exposed to acids.

4) Carbon dioxide is often used as an inexpensive, nonflammable pressurized gas.

Life jackets often contain canisters of pressured carbon dioxide for quick

inflation. Steel capsules are also sold as supplies of compressed gas for air guns,

paintball markers, for inflating bicycle tires, and for making seltzer. Rapid

vaporization of liquid CO2 is used for blasting in coal mines.

5) Carbon dioxide extinguishes flames, and some fire extinguishers, especially those

designed for electrical fires; contain liquid carbon dioxide under pressure. Carbon

dioxide also finds use as an atmosphere for welding, although in the welding arc,

it reacts to oxidize most metals. Use in the automotive industry is common despite

14.4

Synthesis of Chemicals from Carbon dioxide

significant evidence that welds made in carbon dioxide are quite delicate than

those made in more inert atmospheres, and that such weld joints depreciate over

time because of the formation of carbonic acid. It is used as a welding gas

primarily because it is less expensive than more inert gases such as argon or

helium.

6) Liquid carbon dioxide is a good solvent for many organic compounds and it has

begun to attract attention in the pharmaceutical and other chemical processing

industries as a less toxic alternative to more traditional solvents such as organic

chlorides. It's used by some dry cleaners for this reason.

7) Plants require carbon dioxide to conduct photosynthesis, and greenhouses may

enrich their atmospheres with additional CO2 to boost plant growth. It has been

proposed that carbon dioxide from power generation be bubbled into ponds to

grow algae that could then be converted into biodiesel fuel. High levels of carbon

dioxide in the atmosphere effectively exterminate many pests. Greenhouses will

raise the level of CO2 to 10,000 ppm (1%) for several hours to eliminate pests

such as whitefly, spider mites, and others.

8) In medicine, up to 5% carbon dioxide is added to pure oxygen for stimulation of

breathing after apnea and to stabilize the O2/CO2 balance in blood.

9) A common type of industrial gas laser, the carbon dioxide laser, uses carbon

dioxide as a medium.

10) Carbon dioxide is commonly injected into or adjacent to producing oil wells. It

will act as both a pressurizing agent and, when dissolved into the underground

crude oil, will significantly reduce its viscosity, enabling the oil to flow more

rapidly through the earth to the removal well. In mature oil fields, extensive pipe

networks are used to carry the carbon dioxide to the injection points.

Carbon dioxide - Dry Ice

1) Dry ice is a generalized trademark for solid ("frozen") carbon dioxide. Prest Air

Devices, a company formed in Long Island City, New York in 1923, coined the

term in 1925.

Synthetic Strategies in Chemistry

14.5

2) Dry ice at normal pressures does not melt into liquid carbon dioxide but rather

sublimates directly into carbon dioxide gas at -78.5 °C (-109.3 °F). Hence it is

called "dry ice" as opposed to normal "wet" ice (frozen water).

3) Compressing carbon dioxide gas to a liquid form, removing the heat produced by

the compression, and then letting the liquid carbon dioxide expand quickly

produce dry ice. This expansion causes a drop in temperature so that some of the

CO2 freezes into "snow", which is then compressed into pellets or blocks.

Supercritical Carbon dioxide

Carbon dioxide also could be used more widely as a solvent and for example

super critical CO2 (the state existing at 31.0C and 72.8 atm). Now a days Carbon dioxide

could be used more widely as a solvent and for example supercritical carbon dioxide

offers advantages in terms of stereo chemical control, product purification synthesizing

fine chemicals and pharmaceuticals. People are extracting caffeine from coffee by using

supercritical carbon dioxide. More over the advantage of using CO2 is oil gas recovery

and ponds of genetically modified algae that can convert power plant CO2 into biodiesel.

As noted above, CO2 is generally considered to be a green or environmentally benign

solvent and is naturally abundant. CO2 has been suggested as a sustainable replacement

for organic solvents in a number of chemical processes and is currently used in the dry

cleaning, and in parts degreasing. While CO2 is certainly not a panacea, there are a

number of characteristics, which suggest that CO2 could provide environmental and

economic benefits. The nontoxic nature of CO2 has a number of advantages. For

example, in food and pharmaceutical applications, usage of CO2 greatly reduces future

liability costs and can also facilitate regulatory approval of certain processes. An example

is the conversion of pharmaceuticals into nanometer-size particles for injectable use.

Another instance in which supercritical carbon dioxide could be advantageous is in

situations involving contact between hydrophilic and hydrophobic solvents. In this case,

the mutual solubility of the two phases is designed to be small. However, some cross-

contamination is inevitable, typically leading to a costly remediation. The use of CO2 as

the hydrophobic phase produces contamination that is both benign and readily reversible.

Examples include liquid-liquid extraction between organic and aqueous phases as well as

emulsion polymerization of water-soluble monomers. In applications where emissions are

14.6

Synthesis of Chemicals from Carbon dioxide

unavoidable, CO2 is relatively benign to the environment. Examples range from use of

CO2 in enhanced oil recovery to use as a foaming agent or as the solvent in dry cleaning.

Using supercritical CO2 as a solvent also has advantages that arise from chemical and/or

physical properties. In reactions involving gaseous reactants in liquid phases, the use of

supercritical CO2 with its ability to dissolve large amounts of most gases could allow

kinetic control of reactions as opposed to limiting of reaction rates by the transport of the

gaseous reactant across the gas-liquid interface. In reactions where CO2 is a reagent, its

use as a solvent would also favor the reaction. Carbon dioxide may also offer advantages

in reactions such as free-radical polymerizations and oxidations where a chemically inert

solvent is required.

CHEMICALS SYNTHESIS FROM CARBON DIOXIDE

It is well known that CO2 is very stable gas and highly unreactive but plants are utilizing

it for example in the photosynthesis of carbohydrate from CO2. Can we also find the

ways to make chemicals from CO2 artificially? Surely it will be an environmentally

benign route, and this process will lead to green chemistry. The main process which use

CO2 are

1) Synthesis of urea.

2) Synthesis of salicylic acid

3) Synthesis of cyclic carbonate and polycarbonate

4) Synthesis of methanol.

Synthesis of urea by using CO2 currently is a well-established process. The capacity is

approximately 90 million metric tons per annum as per 1997 statistics. Other reactions

are in pilot plant scale. Besides to these reactions there are many reactions, which utilize

CO2. It will be a great feed stock for making commodity chemicals, fuels and materials. It

already plays a major role for a variety of applications. But there are few catches. One is

that CO2 is very stable, which means it takes extra effort to achieve the molecules so that

it will react. Professor Christopher. M. Rayner of the University of Leeds, in England,

has been working on CO2 conversion. He published a review article recently on the

potential of CO2 in synthetic organic chemistry. Approximately 115 million metric tons

of CO2 is used annually by the global chemical industries but really that does not

compare to the approximate 24 billion metric tons. Bulk chemicals already produced

Synthetic Strategies in Chemistry

14.7

routinely from CO2 include urea to make nitrogen fertilizers, salicylic acid as a

pharmaceutical ingredient, and polycarbonate based and plastics. The simplest reactions

of CO2 are those in which it is simply inserted into an X-H bond. Examples are the

insertion of CO2 into organic amines to afford carbamic acids, which may be converted

into organic carbamates. More recent examples include the insertion of CO2 in P-N bonds

of P (NR2)3 compounds to form P (NR2)(OCONR2)

compounds and the reaction of

ammonium carbamates (derived from CO2) with alkyl halides in the presence of crown

ethers to form useful urethane intermediates. This is an example of using CO2 to replace

phosgene, a highly toxic intermediate in chemical synthesis. Reactions are known in

which CO2 undergoes insertion into Sn-C bonds of allyl tin compounds to form

carboxylated allyl derivatives and which are catalyzed by Pd complexes. Another

interesting reaction is the insertion of CO2 into alkanes such as methane to form acetic

acid.

The activation of a C-H bond and CO2 insertion are much fascinating .The

thermodynamics of this reaction are marginal; however, adjusting the reaction conditions

and coupling this reaction with energetically favorable product processes could improve

conversion efficiencies. Carbonates, (RO)2CO, can also be prepared by inserting CO2 into

O-H bonds followed by dehydration or by oxidative carboxylation of olefins. This

synthetic approach has the possibility of providing a new route to compounds that have

very large potential markets. Related reactions in which CO2 is incorporated into product

molecules without reduction have been used in the synthesis of polymers.

The groups of Inoue and Kuran performed initial work in this area. In recent years, a

number of new catalysts have been developed for co polymerization of CO2 and oxiranes

to form polycarbonate. These studies have increased the productivity of this reaction by

100 times and have also expanded the range of applicable monomers (oxiranes).

Polypyrones are another potentially interesting new class of polymer. It has been

prepared from diacetylenes and CO2 in the presence of Ni catalysts; a related reaction is

the telomerization of butadiene and CO2 to produce lactones. Urethanes have also been

prepared by the reactions of dicarbamate ions formed by insertion of CO2 into diamines,

followed by Pd-catalyzed coupling to 1,4-dichloro-2-butene. Reductive carboxylations in

which the CO2 unit is incorporated into the product are also known.

14.8

Synthesis of Chemicals from Carbon dioxide

In the case of alkynes and olefins, electrochemical reductive carboxylations result in

effective addition of the formic acid C-H bond to C-C double or triple bonds. For

example, building on the earlier stoichiometric results of Hoberg, Dunach and co-workers

used Ni bipyridine complexes and sacrificial Mg anodes to reductively couple acetylene

and CO2 to form propenic acid. Similarly, Sylvestri reported that the reductive coupling

of CO2 with styrene is catalyzed by benzonitrile. Bromoarenes can also be reductively

carboxylated to form the corresponding carboxylic acid using Ni diphosphine catalysts.

More recently, the sequential reductive coupling of two molecules of CO2 to butadiene to

form 3-hexen- 1,6-dioic acid has been reported. This approach provides a new route to a

Nylon precursor. Another important monomer, ethylene, can be prepared by

electrochemical reduction of CO2 in aqueous solutions with current efficiencies as high as

48%. The production of this monomer by this remarkable 12-electrons reduction offers a

potential route to polyethylene from CO2. The preceding results clearly indicate that it

may be possible to produce a large variety of polymers in the future using materials

derived from CO2.

Under oxidative conditions, CO2 may react with olefins to give cyclic carbonates that

find wide industrial applications. In these transformations heterogeneous catalysts are

currently more promising and viable than homogeneous ones. Another potentially useful

reaction of CO2 is the dehydrogenation of hydrocarbons. Examples are the

dehydrogenation of ethyl benzene and propane over metal oxides to form styrene and

propene, respectively. In these reactions, no part of the CO2 molecule is incorporated into

the organic product, rather the oxygen of CO2 serves to remove two H atoms of the

hydrocarbon. CO2 is currently used as an additive in the synthesis of methanol from CO

and H2, and it is believed that reduced forms of CO2 are kinetically important

intermediates in this process. Recently, efficient heterogeneous catalysts have been

developed for CO2 hydrogenation to methanol. However, the thermodynamics for

methanol production from H2 and CO2 are not as favorable as that for production of

methanol from H2 and CO. For example, at 200 °C the equilibrium yield of methanol

from CO2 is slightly less than 40% while the yield from CO is greater than 80%. The

reduction of CO2 can be rendered more favorable by the use of hybrid catalysts that

dehydrate methanol to form Dimethyl ether. Other copper-zinc based catalysts have also

Synthetic Strategies in Chemistry

14.9

been used for methanol synthesis. Fisher and Bell et al. studied Cu/ZrO2/SiO2 catalysts

by in-situ infrared spectroscopy and suggested some mechanism for the route to

methanol. Ethanol has also been produced by the hydrogenation of CO2. This fuel is

attractive because it has a somewhat higher energy density than methanol and it is not as

toxic. However, the selectivity for ethanol production is comparatively low (<40%).

The hydrogenation of CO2 to methane and higher hydrocarbons is also known. For C2

and higher hydrocarbons, hybrid catalysts such as Cu-ZnO-Cr2O3 and H-Y zeolite are

generally used. Noyori et al. have carried out pioneering work on the catalytic synthesis

of formic acid derivatives by CO2 hydrogenation, together with other substrates, in

supercritical CO2. In part because of the high solubility of H2 in CO2, an economical

synthesis of dimethylformamide is achieved.

Homogeneous catalysts are also known to mediate the rapid hydrogenation of CO2 to

formate, because this reaction is not thermodynamically preferential, amines and

supercritical CO2 have been used to drive this reaction. Under the appropriate conditions,

very high turnover numbers and rates can be achieved. For example, Leitner et al.

examined complexes of the general type [R2P-(X)-PR2]Rh-(hfacac) (X = bridging group;

hfacac) 1,3-bis-(trifluoromethyl)-acetonylacetonate). All the compounds are active

catalysts for formic acid production from H2 and CO2, but the most effective has X=

(CH2)4 and R= cyclohexyl showing good results at 25 °C and 40 atm of 1:1 H2: CO2. The

selectivity to formic acid is nearly 100%.

Possible pathways for the opposing interaction of Low-Valent Catalysts with Protons

or CO2 of the CO2 reduction product observed. If the reduced form of the catalysts reacts

with CO2 to form a M-CO2 complex, protonation yields a metallo carboxylic acid; further

reaction can then produce CO by C-O bond cleavage to form hydroxide or water. Thus,

reaction of a reduced form of the catalyst with CO2, as opposed to protons, leads to CO

formation. If the reduced form of the catalyst reacts with protons to form a hydride

complex, subsequent reaction of the hydride with CO2 leads to formate production. An

interesting example of such selectivity is CO2 electrochemical reduction catalyzed by

polymeric films based on [Ru(N-N)(CO)2]n (N-N=poly pyridine ligand) in aqueous

media. Deronzier and Ziessel et al. found that bipyridyl ligands with electron

withdrawing groups in the 4,4 positions gave catalysts which are highly selective for

14.10

Synthesis of Chemicals from Carbon dioxide

formate at pH >5 while those derived from the unsubstantiated 2, 2 -bipyridine or the 4,

4 -dimethyl analogue primarily give CO at pH > 7.165 Formate was thought to arise

from an intermediate metal hydride, whereas CO was thought to arise from a metallo

carboxylicacid generated by carbonation of an intermediate anion followed by

protonation. It is unusual for homogeneous catalysts to form reduction products that

require more than two electrons.

However, Tanaka and co-workers, reported that the formation of glycolate

(HOCH2COO-), glyoxylate (OCHCOO-), formic acid, formaldehyde, and methanol as

CO2 reduction products using [Ru(tpy)(bpy)(CO)]2+ complexes as electro catalysts (bpy =

2,2 -bipyridine, and tpy =2,2 :6 ,2

-terpyridine).Although turnover numbers were

not given for these highly reduced species, their formation raises the exciting possibility

that a single-site catalyst can result in multi electron reductions of CO2 and even C-C

bond formation.

Tanaka and Gibson et al. recently succeeded in isolating key Ru C1 compounds with

polypyridine ligands that are models for catalytic intermediates. Gibson et al. also

isolated ReC1 complexes with polypyridine ligands. The importance of photochemistry in

reactions of some have the Re and Ru complexes has been demonstrated. The formation

of formaldehyde has also been reported in electrochemical CO2 reduction using transition

metal terpyridine complexes polymerized on glassy carbon electrodes. The relatively

mild conditions and low over potentials required for some of the homogeneous catalysts

make them attractive for future studies; however, a number of barriers must be defeated

before useful catalysts are available for fuel production.

Photochemical reduction of CO2 is one of the significant reactions many of the

reactions described above rely on energy input either in the form of reactive bonds

(alkenes, alkynes, etc.), hydrogen, or electricity. Photochemical systems have been

studied in an effort to develop systems capable of directly reducing CO2 to fuels or

chemicals using solar energy. Transition-metal complexes have been used as both

catalysts and solar energy converters, since they can absorb a significant portion of the

solar spectrum, have long-lived excited states are able to promote the activation of small

molecules, and are forceful. Carbon dioxide utilization by artificial photo conversion

presents a challenging alternative to thermal hydrogenation reactions, which require H2.

Synthetic Strategies in Chemistry

14.11

The systems studied for photochemical CO2 reduction studies can be divided into several

groups: Ru(bpy)32+ both as a photo sensitizer and as a catalyst. Ru(bpy)32+ as a photo

sensitizer and another metal complex as a catalyst. ReX (CO) 3(bpy) or a similar complex

as a photosensitizers. Ru(bpy)32+ and Ru(bpy)32+ type complexes as photo sensitizers in

microheterogeneous systems. Metalloporphyrins also act as a photosensitizers and

catalyst. Photochemical CO2 reduction is normally carried out less than 1.0 atm CO2 at

room temperature. Therefore, the concentration of dissolved CO2 in the solution is low

(e.g., 0.28 M in CH3-CN, 0.03Min water). These systems produce formate and CO as

products. In the most efficient systems, the total quantum yield for all reduced products

reaches 40%. In some cases with Ru or Os colloid, CH4 is produced with a low quantum

yield. Under photochemical conditions, the turnover number and the turnover frequency

are dependent on irradiation wavelength, light intensity, irradiation time, and catalyst

concentration, and they have not been optimized in most of the photochemical

experiments described. Typical turnover frequencies for CO or HCOO- are between 1 and

10h-1, and turnover numbers are generally 100 or less. The abovementioned molecular

sensitizers can be replaced with semiconductor electrodes or particles to achieve light

harvesting. These systems may use enzymes or catalysts to promote electron transfer

from the semiconductor-solution interface to CO2 or reduce CO2 directly. Typically these

reductions require a potential bias in addition to solar energy input to achieve CO2

reduction and electrode corrosions a major concern. This corrosion can some times be

defeated

using high

CO2

pressures.

Fascinating

examples

stoichiometric

photochemical reactions of CO2 promoted by metal complexes have also been reported.

Thus, Aresta et al. found that CO2 can be incorporated into cyclopropane to afford

butyrolactone. Kubiak et al. demonstrated the reduction of CO2 to the radical anion and

subsequent coupling to cyclohexene by the use of a Ni complex.

Ranyar et al. have worked on the catalytic processes for reducing CO2 to formic acid.

It has potential of power fuel cell for electricity generation and automobiles and as a

precursor for other fuels, synthetic chemicals and fibers, including polymers.

Conversion of CO2 to CO will be more challenging process because CO can be used

in a host of organic synthesis and one of the important feed stock in the chemical industry

for making higher hydrocarbon through Fisher-Tropsch Synthesis.

14.12

Synthesis of Chemicals from Carbon dioxide

Nicolas Eghbali and his group working on conversion of CO2 and olefins into cyclic

carbonates in water. Geoffrey W.Coates et al. have developed the catalyst to incorporate

CO2 into polymers by using β-diminate zinc acetate and salen cobalt carboxylate

complexes. These catalysts promote alternating co polymerization of various epoxides

with CO2 to make biodegradable aliphatic polycarbonate. The polymers which contain

30-50% CO2 by weight have gas barrier and degradation properties that make them

attractive for feed packaging foam-casting to make automotive parts and electronic

processing applications. These kinds of polymers also can be used to replace propylene

oxide segments in polyurethane foams, which would help cut costs. The foams are used

for insulation and seat cushions, among other applications

About 150 million tons of plastics produced globally in a year, and most of it is non-

bio degradable and from energy intensive processes that use petroleum-based feedstocks.

Coastes et al. working on limeonene oxide derived from citrus fruit waste as a

potential epoxide monomer for co-polymerization with CO2.other research in progress

involves developing a catalytic system that can use untreated CO2 directly from industrial

waste streams to make polymer.

Artificial bio inspired systems is far less complicated and therefore easier to study

than natural photosynthesis, in which sun light water and CO2 are converted into O2 and

carbohydrates.

By using inorganic material, people are utilizing the carbon dioxide. The reaction of

CaCO3 and CO2 in water to form Ca (HCO3)

is responsible for the fixation of large

quantities of CO2 in the oceans. However, it is kinetically slow. Similarly, CO2 can also

fixed

by naturally occurring minerals.

Even

though

the

reactions

are

thermodynamically favorable, they are slow and would need to be enhanced kinetically

before they could contribute significantly to adjusting the carbon balance. In addition,

this would generally require mining and processing enormous amounts of materials to

store relatively little CO2.Currently, large quantities of CaCO3 are converted into CaO

and CO2 (which is released into the atmosphere) in cement manufacture. If a natural ore

could be substituted for CaO, a significant release of CO2 into the atmosphere could, in

principle, be avoided.

Synthetic Strategies in Chemistry

14.13

Fujita has found success by using rhenium tri carbonyl complexes to mediate CO2

reduction. The researchers homed in on one set of catalysts bearing bipyridine (bpy)

ligands which includes (bpy) Re(CO)3 and its di rhenium analog. But the reaction rates

for co production are slow due to the stability of CO2

People are working on CO2 → CO but ultimate target is CO2 to Methanol that could

be used as a fuel.

All Possible Reactions

Fig. 14.1. Overall chemical transformations

(reproduced from Hironiri Arakawa, chemical Reviews, 101 (2001) 976)

CONCLUSION

Synthesizing chemicals from carbon dioxide is one of the challenging process as well as

eco-friendly and environmentally benign route. Using carbon dioxide as a raw material

14.14

Synthesis of Chemicals from Carbon dioxide

never going to reduce atmosphere CO2 level or it will be very little the effect on climate

change but we can reduce the production of CO2 and reduce the usage of fossil fuel and

shall we make it?

REFERENCES

1. J. M. Desimone, Science, 265 (1994) 359

2. Hironiri Arakawa, chemical Reviews, 101 (2001) 976

3. Chemical & Engineering News, April 30, 2007, 11

4. Chemistry & Industry, July13, 2007, 13

5. X. Xiaoding, J. A. Moulijin Energy and Fuels, 10 (1996) 305

6. Greenhouse issues 1992 Feb

7. M. A.Scibioh and B.Viswanathan Proc.Indian Natn Sci Acad., 70 A (3) (2004) 407

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