Moises A. Carreon University of Louisville Chemical Engineering Dept.

macarr15@louisville.edu

Metal Organic Frameworks as Catalysts in the Conversion of CO2 to Cyclic Carbonates

2013 Kentucky Innovation & Entrepreneurship Conference. Lexington KY

August 29, 2013

Global Carbon Dioxide Emissions

CO2 emission almost tripled from 1965 to 2011

Carbon Dioxide Emissions by region

Global

warming

……

Glacier

melting

Chemicals !!!

Solution???

Conversion of CO2 into useful chemicals

Types of CO2 Transformation

T. Sakakura, J.C. Choi, H. Yasuda Chem. Rev. 2007, 107, 2365

Why CO2 conversion to chemicals?

There are several motivations for producing chemicals from CO2 :

(1) CO2 is a cheap, non-toxic and non-flammable feedstock that can

frequently replace toxic chemicals such as phosgene or isocyanates.

(2) CO2 is a totally renewable feedstock compared to oil or coal.

(3) The production of chemicals from CO2 can lead to totally new materials

such as polymers.

(4) New routes to existing chemical intermediates and products could be

more efficient and economical than current methods.

(5) The production of chemicals from CO2 could have a small but significant

positive impact on the global carbon balance.

Useful Products Obtained from Carbonates and

Carbamates

Carbonates polar aprotic solvents

electrolytes in secondary batteries

precursors for polycarbonate materials

polyurethanes

pesticides

fungicides

medicinal drugs

synthetic intermediates

Carbamates

Conventional Catalysts for Carbonate Synthesis

Catalyst Disadvantages

Metal complexes

toxic, water- and air-sensitive, causing

handling problems and requiring high

temperature/pressure

Schiff bases, porphyrines and

phthalocyanines requiring an additional cocatalyst

Metal oxides

weakly active, requiring a very high

catalyst/substrate ratio, a substantial

amount of solvent and long reaction

times

Quaternary ammonium salts requiring high temperature/pressure

Mesoporous materials requiring high temperatures and a

functional group

Zeolites requiring high temperature

The need for novel Catalysts………..

The development of superior performance catalysts requires novel materials with fundamentally different structural, compositional, adsorption and transport properties than those of conventional zeolites, metal oxides or metal phases.

In this respect, metal organic frameworks (MOFs) have emerged as novel crystalline microporous materials with highly desirable properties, such as uniform micropores, high surface areas and open porous framework structures with large accessible pore volumes making them potentially interesting candidates for catalytic applications.

Catalytic Conversion of CO2 to Carbonates

RR

CO2O

OO

O

+

Epoxide Cyclic Carbonate

R = -CH3, -CH2Cl, -C6H5

MOFs are ideal materials to effectively catalyze this reaction

MOF

What is a MOF?

Metal building block (ZnN4)

Organic linker MOF

MOFs are novel type of crystalline porous materials with highly desirable

properties, such as uniform micropores, high surface areas, and exceptional thermal

and chemical stability.

ZIF-8

Lewis acid site (Zn or Cu)

Organic linker

ZIF or Bio -MOF Structure

CO 2 reacts at Lewis acid sites

CO 2 adsorbs at basic unitsof the organic linker

Surface Reaction

O=C=O

O=C=O

O=C=O O=C=O

CO 2 adsorption

(a) (b) (c)

ZIF-8 or Cu3(BTC)2 ZIF-8

Lewis acid

site

(a) Main components of ZIF-8, (b) CO2 adsorbing at the organic unit sites, (c)

Adsorbed CO2 reacts at the Lewis acid sites.

ZIF-8 is an appealing material to employ as catalyst for CO2 conversion

1. Preferential high CO2 adsorption capacity (Ideal catalysts for the conversion

of CO2 to cyclic carbonates should be those exhibiting high CO2 uptakes)

2. The presence of Lewis acid sites in its framework (Lewis acid sites are known

to catalyze the reaction of CO2 with epoxides to give propylene carbonates

and other precursors of polycarbonates )

ZIF-8 an appealing MOF catalyst for cyclic

carbonates synthesis

0 1 1

0 0 2

1 1 2

0 2 2

0 1 3

2 2 2

2 3 3

2 4 4

2 3 5

1 3 4 b

c

2 nm

d

5 10 15 20 25 30 35

Inte

nsi

ty (

a.u

.)

2θ (degree)

(0 1

1)

(00

2)

(02

2)

(11

2)

(2 3

3)

(1 1

4)

(01

3)

(2 2

2)

(2 3

5)

(24 4

)(0

4 4

)

(1 3

4)

a

0

0.5

1

1.5

2

2.5

0 30 60 90 120

Ad

sorp

tion

ca

pa

cit

y (

mm

ol/

g)

Pressure (KPa)

f

280

300

320

340

360

380

0 0.2 0.4 0.6 0.8 1

Qu

an

tity

ad

sorb

ed (

cm3/g

ST

P)

Relative Pressure (P/Po)

eCO2/CH4 ratio = ~14

ZIF-8 crystals ( synthesis and characterization)

We have developed in our lab “wet-chemistry routes” to

prepare ZIF-8 crystals with controlled crystal size

Epichlorohydrin CO2

P,T, time

ZIF-8

Chloropropene Carbonate

Catalytic performance of ZIF-8 in the Conversion of CO2

to Chloropropene Carbonate

The conversion of epichlorohydrin reached a maximum of ∼100% at 100 °C, while

the selectivity to chloropropene carbonate decreased.

The highest chloropropene carbonate yield was observed at 80 °C.

ZIF-8 an effective catalyst for carbonate synthesis

O

R

O=C=O

O

R

O=C=O-

O

R

O=C=O-

O

R

O

O

Basic siteAcid site

(a) (b)

(c)(d)

Reaction mechanism for the catalytic conversion of CO2 and epoxides to cyclic carbonates

over MOFs: (a) adsorption steps, (b) nucleophilic attack, (c) ring opening, (d) ring closure.

Mechanism for CO2 conversion to cyclic carbonates

over MOFs

MOFs as catalysts for the synthesis of carbonates

1. The utilization of CO2 as a renewable raw material for the production of chemicals is an

area of great societal importance.

2. In particular, the catalytic conversion of CO2 into cyclic carbonates, which are useful

chemical intermediates employed for the production of plastics and organic solvents,

represents an appealing approach for the efficient use of CO2.

3. Metal organic frameworks MOFs, have emerged as novel porous materials which

combine highly desirable properties, such as uniform pores in the micro and mesoscales,

high surface areas, flexible chemistries, and exceptional thermal and chemical stability,

making them ideal candidates for catalytic applications.

4. The catalytic ability of these porous materials for the synthesis of cyclic carbonates from

CO2 have been presented.

5. Surface features of the MOFs such as acidity (presence of acid sites), and adsorption

selectivity (presence of basic sites), as well as textural features such as surface area, pore

size, and pore volume play a critical role on the overall catalytic performance of these

porous phases.

Conclusions

Representative Publications

•1) M. Zhu, D. Srinivas, S. Bhogeswararao, P. Ratnasamy, M.A. Carreon*, Catalytic activity of ZIF-8 in

the synthesis of styrene carbonate from CO2 and styrene oxide”, Catalysis Communications 2013, 32,

36-40.

• 2) E.E. Macias, P. Ratnasamy, M.A. Carreon* “Catalytic activity of metal organic framework

Cu3(BTC)2 in the cycloaddition of CO2 to epichlorohydrin reaction” Catalysis Today 2012, 198, 215-

218.

• 3) M.A. Carreon * “Metal Organic Frameworks as Catalysts in the Conversion of CO2 to Cyclic

Carbonates” In. J. Chem. A (invited) 2012, 51A, 1306-1314

• 4) C. Miralda, E.E. Macias, M. Zhu, P. Ratnasamy, M.A. Carreon*, “Zeolitic imidazole Framework-8

catalysts in the conversion of CO2 to chloropropene carbonate” ACS-Catalysis 2012, 2, 180-183.

Acknowledgements Personnel: Ms. Minqi Zhu

Ms. Carmen Miralda

Ms. Zhenzhen Xie

Mrs. Eugenia Macias

Funding: KSEF -2361-RDE-014

Mahendra Jain

Maria Labreveux

Spring 2013. Graduate research group: Carmen Miralda, Zhenzhen Xie,

Minqi Zhu, Moises Carreon, Masoudeh Ahmadi, Hugo Nambo, Joseph

Bohrman (not pictured), Eugenia Macias (not pictured)

Collaborators: Dr. P. Ratnasamy (Conn Center)

Dr. D. Srinivas (NCL, India)