Metal-Free Activation of CO2

Hariprasad NarayananNational Centre for Catalysis ResearchIndian Institute of Technology Madras

Current Work : Design of efficient materials for photocatalytic conversion of CO2

Global Initiative of Academic Network (GIAN) CourseScience and Technology In Carbon Dioxide Conversion

November 7-14, 2016Centre for Climate Change and Adaptation Centre, Anna University

MEA

DEA

TEA

• Degradation• Loss of MEA/DEA/TEA• Toxicity• Cost

• Less Volatile• Lower Loss

Polyamines

AMINES

ACTIVATION OF CO2

Photosynthetic system involves the formation of a carbamate as the first step ofthe cycle, by the action of a number of cyanide-based, nitrogen-rich,conjugated organic molecules, such as nucleic acids, porphyrins, andphthalocyanines.

(1) 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) (2) Porphin(3) Adenine grafted onto silica (Silylamines)(4) Idealized repeating motif of graphitic C3N4.

Why Carbon Nitride?

• There are a number of handles in this system by which the functionality ofthis material can be varied even though it is predominantly graphitic innature.

• The important ones are the increased free electron concentration (dependingon the content of heteroatom) and also the feasibility of anchoring activespecies by the amide groups.

• This system is two dimensional and hence has its own specificities ascompared to the conventional three dimensional systems commonlyemployed. Possibly low dimensional systems may be appropriate for electrontransfer reactions due to the possibility of vectorial nature of the chargetransfer.

Catalytic Activities of MCNs for Phenol Production from Benzene via Carbon Dioxide Activation

Catalyst Conversion of 3 (%) Selectivity of 4 (%) Selectivity 5 (%)MS-MCN 30 71 29UF-MCN 29.9 89 11MG-MCN 20.7 86 14

Reaction conditions: 20 mg catalyst, 10 ml DMF, temperature 423 K, 80 psi CO2, 10 h. MS : Melamine, UF: Urea-Formaldehyde, MG : Melamine-Glyoxal

Green Chem., 13, 1416-1421, 2011

Cycloaddition of CO2 to Propylene Oxide Over Carbon Nitride

Catalyst Conversion of 1 (%) Selectivity of 2 (%)MS-MCN 34 90UF-MCN 28 92MG-MCN 25 98

Reaction conditions: 20 mg catalyst, 10 ml DMF, temperature 373 K, 80 psi CO2, 10 h. MS : Melamine, UF: Urea-Formaldehyde, MG : Melamine-Glyoxal

Green Chem., 13, 1416-1421, 2011

CO2 Conversion into Cyclic Carbonates

Catal. Sci. Technol., 2014,4,1556–1562

Catal. Sci. Technol., 2014,4,1556–1562

Oxidation of Cyclic Olefins

Reaction conditions: 20 mg catalyst, 10 ml DMF, temperature 373 K, pressure 80 psi, gas ratio 0.333, time 10 h; Product analyzed by GC and GC-MS.a Trace amount of diol was observed.

MS : Melamine, UF: Urea-Formaldehyde, MG : Melamine-Glyoxal

Green Chem., 13, 1416-1421, 2011

Angew. Chem. Int. Ed. 10.1002/anie.201607552

Joint Center For Artificial Photosynthesis

Photocatalytic CO2 Reduction

Phys.Chem.Chem.Phys., 2015, 17, 6280

Conclusion and Perspectives• Carbon Nitride seems to be an excellent material for CO2 capture and

utilization but its potential is not yet fully revealed.• More intense studies are required in this area to prove the identity of

carbon nitride towards carbon dioxide utilization.• It is also a well known photocatalyst and became a tight competitor to the

titanium dioxide centric photocatalysis!• Boron Carbon Nitrides• There is no presently known catalyst that can facilitate carbon dioxide

solar conversion to fuels with high efficiency and selectivity. Achievingcontrolled catalysis would be a revolutionary scientific achievement thatcould pave the way to a scalable technology that converts carbon dioxideto liquid fuels with only solar added energy.

It is better to quote from Micheal Schmidt “Further improvementsin CO2 catalysis are possible, not only for the elimination of theCO2

●− intermediate but also for eliminating the more stableformate, CO, and formaldehyde intermediates for the synthesis ofuseful methanol and methane fuels. It must be remembered,however, that no matter what achievements are made in catalysis,the fundamental thermodynamics of the overall problem willnot be changed and a substantial input of energy will beneeded for conversion of CO2 to more reduced carbonproducts”.

“I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that. I wish I had more years left”

Thomas Edison, 1930

“It is time to build an actual artificial photosyntheticsystem, to learn what works and what doesn't work, andthereby set the stage for making it work better.”Melvin Calvin,1958

“On the arid lands there will spring up industrial colonieswithout smoke and without smokestacks; forests of glasstubes will extend over the plains and glass buildings willrise everywhere; inside of these will take place thephotochemical processes that hitherto have been theguarded secret of the plants, but that will have beenmastered by human industry which will know how to makethem bear even more abundant fruit than nature, fornature is not in a hurry and mankind is. And if in a distantfuture the supply of coal becomes completely exhausted,civilization will not be checked by that, for life andcivilization will continue as long as the sun shines!”

Giacomo Luigi Ciamician, 1913