1.
Project proposal on Utilization of CO2
The combustion of fossil fuels such as coal, petroleum, and natural gas has
generated a huge amount of greenhouse gas CO2. In the atmosphere, the CO2
concentration has increased by 30% since the late of 19th century and will increase
doubly over the next 2 decades. This has substantially led to severely adverse impacts on
the environment like air pollution and global warming. How to reduce the CO2 is
currently a key issue in environmental protection, and need to reduce the accumulation of
CO2 into the atmosphere requires new technologies.
Nature utilizes CO2 to produce myriad substances that are consumed by humans
and animals. Some industrial processes aim to accelerate the utilization of CO2. There are
essentially three pathways for utilizing CO2.
(1)
Conversion of CO2 into fuel,
(2)
Utilization of CO2 as a feedstock for chemicals, and
(3)
Non-conversion use of CO2.
The various utilization technologies together have the potential to reduce CO2
emissions by at least 3.7 gigatons/year (Gt/y) (approximately 10 % of total current annual
CO2 emissions), both directly and by reducing use of fossil fuels. However, much greater
reductions are possible through wider adoption of these technologies.
Present research:
In recent years, carbon dioxide has found a growing application as a fluid in drycleaning, refrigerators, air conditioners, fire-extinguishers, separation techniques, water
treatment and the food- or agro-chemical industry (as packaging, an additive to beverages
or a fumigant). Supercritical-CO2 finds an application as a solvent for reactions1, nanoparticle or -composite production, and polymer-modification. In all the above
technological applications, CO2 is not converted into other chemicals, and can be
recovered as such at the end of the application.
The use of CO2 to convert solar energy into biomass and, from there, to various
renewable fuels is now widely supported by industry and governments as a means to
secure future energy supplies and to decrease net CO2 emissions to atmosphere
CO2 storage by adsorbents is an economical and relatively mature method
considering the low cost of equipment and the possible recycling uses of the captured
CO2. Physisorption between certain adsorbents and CO2 molecules could allow
conveniently reversible processes to capture CO2 gas. It requires much less energy
compared to the conventional techniques that use basic species such as aqueous ammonia
and amine functionalized solids to remove CO2 gas. Activated carbon, carbon molecular
sieves, zeolites, Metal organic frameworks and Mesoporous materials have been
extensively studied as adsorbents for CO2 gas.
Carbon dioxide has been used as a chemical feed stock for the synthesis of
organics 2-4, such as carbonates5, polycarbonates, carbamates6, lactones, carboxylic acids,
urea7, isocyanates and epoxides.
Several homogeneous complexes catalyze the CO2-epoxide cycloaddition
reaction. Several heterogeneous catalysts, such as polystyrene-bound onium salts, basic
metal oxides, Mg–Al mixed oxides, Nb(IV) and Nb(V) catalysts , lanthanide
oxychlorides , alkali metal-loaded zeolites and alumina , poly(4-vinylpyridine)-supported
zinc halide , ionic liquids , silica-supported guanidine , and Schiff base and
phthalocyanine complexes covalently bonded to porous silica ,Nucleobase (adenine)modified, mesoporous Ti-SBA-15 (Ti-SBA-15-pr-Ade)
have also been reported.
Commercial production of cyclic carbonates by a nonphosgene route with quaternary
ammonium salt-based catalysts has been announced recently by BASF and
The alternative way for utilization of carbon dioxide currently evokes great
interest as an oxygen source. Park et al reported the soft reported the soft oxidant
behavior of CO2 in the oxidative dehydrogenation of ethylbenzene, toluene and xylene in
both gaseous and liquid-phase8, respectively using zeolite supported iron oxide and
vanadium-antimony oxide catalyst. Recently Ansari et al reported using CO2 as a oxygen
source for the oxidation of cyclic olefins over mesoporous carbon nitride as a catalyst9.
Aim and objective of the project proposal:
Carbon dioxide as a building block for organic products is carried out on various
homogeneous metal complexes in liquid phase and several heterogeneous catalysts such
as. Metal oxides supported on SiO2, Al2O3, zeolites, various type of acid supports and
MgO, HT, CeO2 and various type basic supports, ionic liquids, metal halides anchored
on polymers, metal complexes covalently anchored on porous materials However, with
most of the above-mentioned solid catalysts, the reactions had to be carried out at high
temperatures pressures for high yields. These catalysts lose their activity during the
reaction and in recycle process. On the other hand these catalysts have low surface area
and less number of active sites which participate in the reaction, thus leading to lower
conversion and selectivities.
To overcome the above problems we intend to use the mesoporous supports with
high surface area wherein in the active metal such as Cu, Ni, Fe, Co, and Ag are
supported over these materials. Recently mesoporous materials have vital role in the
heterogeneous catalysis especially in synthesis of various fine chemicals and reaction
intermediates. In the first step we will synthesize acid or base supported mesoporous
materials such as mesoporous heteropolyacid, MgO, HT (hydrotalcite), MCM-41, SBA15, SBA-16, mesoporous carbon by different preparation methods such as hydrothermal
synthesis. In the next step active metals were placed over these supports by methods such
as impregnation as a result a composite catalyst was obtained. We can expect these
composite catalysts with high thermal stability and high surface area may show superior
activity as compared with conventional catalysts. An additional advantage of these
materials is good structure intactness.
Therefore these materials can be effectively used for both vapour phase and liquid
phase reactions. On the other hand recovery and recycling of these catalysts are very
simple and less expensive.
References:
1. A. O. Chapman, G. R. Akien, N. J. Arrowsmith, P. Licence and M. Poliakoff, Green
Chem., 2010, 12, 310–315.
2.
J.-S. Chang, K.-W. Lee and S.-E. Park, ed., Carbon dioxide utilization for global
sustainability, Elsevier, Netherlands, 2004.
3. M.-J. Choi andD.-H. Cho, Clean: Soil, Air,Water, 2008, 36, 426–432.
4. C. He,G. Tian, Z. Liu and S. Feng, Org. Lett., 2010, 12, 649–651.
5. D.J. Daresbourg, J.C. Yarbrough, J. Am. Chem. Soc. 124 (2002) 6335.
6. T. Takeuchi, M. Nishi, T. Irie, H. Ryuto, US Patent 4,469,882 (1984).
7. D. Fromm and D. Lutzov, Chem. Unserer Zeit., 1979, 13, 78.
8. M. S. Park, J.-S. Chang, D. S. Kim and S.-E. Park, Res. Chem.Intermed., 2002, 28,
461–469.
9. M. B. Ansari, B-H Min, Y-H Mo and S- Park , Green Chem., 2011, 13, 1416