Process development for manufacturing
propylene carbonate and poly(propylene) carbonate
from carbon dioxide and propylene oxide
Yaşar Demirel and Hossein Noureddini
Department of Chemical and Biomolecular Engineering
University of Nebraska Lincoln
1
Carbon dioxide as feedstock
CO2 as an alternative feedstock to fossil fuels
to help to mitigate global warming.
Most catalysts require high reaction
temperatures and/or high pressures of CO2
Inoue, Koinuma, Tsuruta, J. Polym. Sci., Part B: Polym. Lett. 1969.
Inoue, Koinuma, Tsuruta, Makromol Chem 1969.
Ree et al., Korea Polymer J. 1999.
PC-Hur et al., Applied Chem. 2003.
Darensbourg et al., JACS, 2003.
Darensbourg and Fitch, Inorganic Chem. 2008.
North and Pasquale-Angew. Chem. Int. Ed. 2009.
2
Properties of propylene carbonate (PC)
•
Cyclic PC(4-methyl-1,3-dioxolan-2-one)- C4H6O3, MW 102.09 g/mol, density
of 1.205 g/ml, melting point of -55 oC (-67oF), boiling point of 240oC
(-464oF), flash point of 132 oC, and autoignition temperature of 455 oC.
•
Important intermediates as the replacement of highly toxic phosgene as
carbonylating agents in processes such as the production of isocyanates or
polycarbonates, drugs and pesticides.
•
Good dielectric in high energy cells and condensers, as an aprotic solvent
and plasticizer for polymers as well as in the removal of CO2 and H2S from
natural gas and petroleum cracking gas.
•
Due to its high dielectric constant of 64, it is frequently used as a highpermittivity component of electrolytes in lithium batteries, usually together
with a low-viscosity solvent .
Lai et al., J. Thermal Analysis and Calorimetry, 2005.
Lu et al., J. Biomed. Mat. Res. A, 2006.
Zaretskii et al., Coke and Chem. 2008.
3
Properties of poly(propylene) carbonate (PPC)
•
PPC is soluble in polar solvents, e.g. acetone, methyl ethyl ketone, ethyl
acetate, dichloroethane, while insoluble in ethyl alcohol, ethylene glycols,
water, and aliphatic hydrocarbons.
•
PPC is amorphous at room temperature. Glass transition temperature is
38°C, thermal degradation temperature is at 252°C, and density is 1.27
g/cm3 at 25°C, 1.9 GPa Young’s modulus and 29 MPa tensile strength.
•
PPC may have potential applications in industry as binder resins,
substitutes of thermoplastic polymers (e.g., polyethylene and polystyrene),
and hydrolytically and/or biologically degradable polymers.
•
Composites of PPC and starch can be used as biodegradable plastics. PPC
is also used in applications where diffusion of oxygen through the structure
is required.
Lai et al., J. Thermal Analysis and Calorimetry, 2005.
Lu et al., J. Biomed. Mat. Res. A, 2006.
Zaretskii et al., Coke and Chem. 2008.
4
Effective catalyst: stable, reusable
• Cycloaddition of CO2 to epoxides is one of the promising reactions
replacing existing poisonous phosgene based synthesis.
• At around 50 bar of CO2 and 60 °C, PO reacts to form PC, PPC.
• Numerous homogenous and heterogeneous catalyst system such
as alkali metal salts alone or in combination with crown ether,
quaternary ammonium salt or phosponium salt, ionic liquids, mixed
oxides, zeolites, metal complexes, have been explored for this
transformation.
• Zinc glutarate, ionic liquids, salen are some of the catalysts used.
• No catalyst system is sufficiently efficient. One gram zinc glutarate
produces only 70 g of PPC in 40 h.
Chisholm et al., Macromolecules 2002.
Inoue, Koinuma, Tsuruta, J. Polym. Sci., Part B: Polym. Lett. 1969.
Ree et al., Korea Polymer J. 1999.
Jagtab et al., Cat. Let. 2006.
Niu et al., J. Poly. Sci. 2007.
5
Cyclic propylene carbonate with SLPC
• Supported liquid phase catalysts
(SLPC) from high surface area
porous silica, polyethylene glycol
(PEG), alkali metal halides.
• These catalysts are highly active
and selective for the synthesis of
cyclic carbonates from carbon
dioxide and epoxides.
• They are not overly sensitive to
the air and moisture and could be
subjected to utilization for several
recycles without obvious loss of
activity.
Mayur et al., Cat. Let. 2006.
6
Cyclic epoxy carbonate with salen+ Bu4NBr
• When bimetallic aluminum(salen) complex 1 used in conjunction
with tetrabutylammonium bromide is capable of catalyzing the
insertion of carbon dioxide into terminal epoxides at 1 atm (760
mmHg) and at ambient temperature.
Melendez et al.,Eur. J. Inorg. Chem. 2007.
North and Pasquale-Angew. Chem. Int. Ed. 2009.
Synthesis of cyclic carbonates from CO2 and
epoxides with salenH2
Role of Bu4NBr in cyclic carbonate synthesis.
rate = k[epoxide][CO2][cat][Bu4NBr]2
7
Propylene carbonate with Cs-P-Si oxide
Cesium–phosphorous–silicon mixed oxide (Cs–P–Si oxide), an acid–base
bifunctional catalyst, efficiently catalyzes propylene carbonate synthesis
from CO2 and propylene oxide under supercritical conditions (8–10 MPa).
Yasuda et al., Appl. Cat. 2006.
8
Cyclic carbonate with ion exchange resins
• Insoluble ion exchange resins,
containing an ammonium salt
or amino group, and the polar
macroporous adsorption resin,
are efficient and reusable
heterogeneous basic catalysts
at around 373 K, 8 Mpa
• It requires no additional
organic solvents either for the
reaction or for the separation
of product.
Du et al., Green Chem. 2005.
9
Cyclic propylene carbonate with ionic liquids
• In this study ionic liquid-1-n-ethyl-3-methylimidazolium chloride
(EMImCl) was used as catalyst in a stirred tank reactor at 212 oF and
114.7 psi with kinetics data published by Hur et al. (2003).
• Ionic liquids are salts consisting of cations and anions with no
measurable vapor pressure.
• Properties Ionic liquids can be adjusted to suit the requirements of a
particular process.
Hur et al., App. Chem. 2003.
Earle, Seddon, IUPAC, 2000.
10
Process flow diagram for propylene carbonate
from PO and CO2
CO2: 9990.2 lb/hr
CO2
S6
C101
E102
S1
PO: 13184.2 lb/hr
PO
SEP101
R101
F101
S3
E101
S4
S5
S8
E103
PC
S7
CATALYST
M101
PC:23174.4 lb/hr
WCAT
CAT: 66 lb/hr
WASTE
MKUPCT
CAT: 66 lb/hr
•
Figure 2.1 Process flow diagram with feed streams carbon dioxide (CO2) and PO (PO), and
product stream (PC).
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Economic analysis of propylene carbonate production
from PO and CO2
Turton et al., 2009.
12
Economic analysis of propylene carbonate production from PO and CO2
Turton et al., 2009.
13
Copolymerization of CO2 and PO
• Inoue’s historic discovery of alternating copolymerization of CO2 and
PO using a ZnEt2-H2O binary catalyst, a wide variety of catalytic
systems have been developed to promote this process.
• Metal salen complexes (SalenMX), (MX:Co, Cr, or Al) alone or in
conjunction with Lewis base salt, or ionic liquid as cocatalysts have
been of significant interest, mainly due to easy synthesis, good
stability against moisture and air.
• Alternating copolymerization of PO and CO2 is possible under mild
conditions, employing sole bifunctional cobalt salen complexes
containing Lewis acid metal center and covalent bonded Lewis base
on the ligand.
Liu et al, J Pol. Sci. 2009.
Inoue, Koinuma, Tsuruta, J Polym Sci: Polym Lett Ed 1969.
Inoue, Koinuma, Tsuruta, Makromol Chem 1969.
Niu et al., J Poly. Sci. 2007.
14
Poly(propylene) carbonate synthesis with zinc glutarate
•
•
•
Poly(propylene carbonate) (PPC) from propylene oxide (PO) and CO2 is
mediated by zinc glutarate and chromium salen complexes.
The properties and composition of the polymer are substantially affected by
copolymerization conditions, namely, temperature, pressure, solvent, and
initial concentration of reactants.
PPC with a molar carbonate linkage percentage of 93% with a zinc glutarate
in toluene at 80.8C and at 4.5 MPa CO2 pressure.
Luinstra and Molnar, Macromol. Symp. 2007.
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Copolymerization of 1,2-epoxycyclohexane
•
Copolymerization of 1,2-Epoxycyclohexane and Carbon
Dioxide Using Carbon Dioxide as Both Reactant and Solvent-
Super et al., Macromolecules 1997.
16
Process flow diagram for poly(propylene) carbonate
from PO and CO2
•
Figure 3.1. Process flow diagram to produce poyl(propylene carbonate) and cyclic propylene
carbonate from CO2 and propylene oxide.
17
Economic analysis of poly(propylene) carbonate production
from PO and CO2
Turton et al., 2009.
18
Economic analysis of poly(propylene carbonate) production
from PO and CO2
Turton et al., 2009.
19
Conclusions
• At around $0.85/lb, PO is a relatively high value commodity; the
current catalysts are very expensive.
• Use of renewable resources such as propylene glycol derived from,
e.g. glycerol of a biodiesel plant at about $0.65-0.75/lb, could prove
to be advantageous over the use of PO in the production of PC and
PPC.
• Not much information is available for the synthesis of PPC from
propylene glycol and CO2. In fact, propylene glycol is used in the
manufacturing of PO which in turn is converted to PC and PPC.
• The existing literature for the synthesis of intermediates and
chemical from CO2 appear promising, however, comprehensive
kinetic study is lacking.
• Some of the more promising routs in this regard need to be explored
further for reaction kinetic in bench scale laboratory experiments.
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