Hydrocarbon Processing - May 2022 - 41

Biofuels, Alternative Fuels and Green Petrochemicals
cycloaddition of CO2
to an epoxide. Its industrial uses
include solvents and transportation of fuel oxygenates.
Polyurethanes synthesis. Polyurethanes
are
O
normally
produced by reacting alcohols with two or more reactive hydroxyl
(eOH) groups per molecule (diols, triols, polyols) with
isocyanates. The environmental concerns of an isocyanates
(R-N=C=O) liquid-phase process-which applies chlorobenzene
and carbonyl chloride-has led to the consideration
of the new technology, which manufactures both polyols and
isocyanates from CO2
via the production of hydroxy-urethane
from cyclic carbonate primary amine. This results in
the manufacture of environmentally friendly non-isocyanate
polyurethanes (Eq. 4):9,10
RNH2 + CO2
r RNCO + H2
O (4)
Polycarbonates. Polycarbonates constitute another group of
CO2
-based polymers. Among them, aliphatic polycarbonates
can be directly produced by reacting epoxides with CO2
. In addition,
aromatic polycarbonates based on bisphenol A (BPA)
can be produced by reacting an epoxide with CO2
to produce
an intermediate that is then polymerized.
Modern technologies of polycarbonate production plants
byproduct from ethylene oxidation to epoxide, leadapply
CO2
ing to CO2 reduction. Also, alternating polycarbonates can be
derived from the reaction between an epoxide and CO2
can be steered to polymeric organic carbonate, as depicted in
FIG. 2. This is performed by suitable catalyst application.11
Electrocatalysis applications in ethylene production.
Electrochemical reduction of CO2
is an attractive process for
ethylene production. Due to higher overpotentials, less selectivity
and low stability, the process needs catalysts capable of
selectively reducing CO2
at lower overpotentials and with long
run times. Various copper-based materials have been evaluated.
The use of support materials like carbon nanostructures has
been successfully employed both to enhance the selectivity and
to increase the robustness of the catalyst.12
In this process, CO2
the cathode with an accompanying evolution of oxygen gas at
the anode in an aqueous solution. For process optimization, a
renewable energy source is applied (Eq. 5 for the cathode, Eq. 6
for the anode):
Anode: 2H2
O r O2
+ 4H+ + 4 e6
7
is
selectively converted to ethylene at
4
5
, which
1
FIG. 2. Polymeric organic polycarbonate structure.
sions in the fields of fuels, chemicals and petrochemical materials.
For the petrochemical industry, the emerging potential of
chemical utilization of recycled CO2
is organic carboxylation
to polymeric carbonates. The purpose of its applications is due
to the development of phosgene-free routes, which utilize CO2
as a feedstock. In these cases, CO2
serves as both carbon and
oxygen sources, replacing CO for making acrylic acid and use
as a mild oxidant. Additionally, its applications extend to environmental
considerations since it is not toxic and can replace
certain toxic building blocks, such as CO and phosgene, for
producing methanol and polyurethane, respectively.
LITERATURE CITED
Sakakura, T., J. C. Choi and H. Yasuda, " Transformation of carbon dioxide, "
Chemical Reviews, June 2007.
2 Aresta, M., Carbon dioxide as chemical feedstock, 1st Ed., Wiley-VCH, 2010.
3
Razali, N. A. M., K. T. Lee, S. Bhatia and A. R. Mohamed, " Heterogeneous catalysts
for production of chemicals using carbon dioxide as raw material: A review, "
Renewable Sustainable Energy Reviews, Elsevier, Vol. 16, 2012.
Liu, Q., L. Wu, R. Jackstell and M. Beller, " Using carbon dioxide as a building
block in organic synthesis, " Nature Communications, January 2015.
Peters, M., et al., " Chemical technologies for exploiting and recycling carbon
dioxide into the value chain, " ChemSusChem, European Chemical Societies
Publishing, 2011.
M. Rezaei, M., S. M. Alavi, Z.-F. Yan and S. Sahebdelfar, " Syngas production by
methane reforming with carbon dioxide on noble metal catalysts, " Journal of
Natural Gas Chemistry, December 2006.
Yano, J., T. Morita, K. Shimano, Y. Nagami and S. Yamasaki, " Selective ethylene
formation by pulse-mode electrochemical reduction of carbon dioxide using copper
and copper-oxide electrodes, " Journal of Solid State Electrochemistry, 2007.
8 Stechel, E. B. and J. E. Miller, " Re-energizing CO2
efficiency, scale and economics, " Journal of CO2
Utilization, 2013.
9
Cathode: 2CO2 + 12+ r C2 H4 + 4 H2O (5) 10
(6)
The application of nanocarbons (carbon nanotube, graphene
-hyoxide,
etc.) possessing high thermal conductivity, high theoretical
specific surface area, unique carrier mobility and an sp2
bridized carbon configuration have shown promotion to CO2
photocatalysis applications, such as hydrocarbon synthesis.7
Takeaways. CO2 is a sustainable resource of carbon that can
partially replace oil and gas in many synthetic applications. Because
it is recovered from industrial plants, it is considered a
renewable, economical and green carbon feedstock.
CO2
recycling can lead to a meaningful impact on CO2
emisvon
der Assen, N., A. Sternberg, A. Kätelhön and A. Bardow, " Environmental
potential of carbon dioxide utilization in the polyurethane supply chain, " EnviR.
Soc. Chem., 2015.
Kathalewar, M. S., P. B. Joshi, A. S. Sabnis and V. C. Malshe, " Non-isocyanate
polyurethanes: From chemistry to applications, " RSC Advances, 2013.
Complete literature cited available online at www.HydrocarbonProcessing.com.
ABBAS EZZAT works as a Petrochemical Professor at
Pharos University and a Distinguished Scientist at the
Materials Science Department within the Institute of
Graduate Studies and Research at Alexandria University.
He is also a local consultant for the Egyptian petroleum
and petrochemical sectors and a Senior Associate Consultant
for Channoil Consulting Ltd. in London. Prior to joining
academia, he occupied several top management positions in the Egyptian
petroleum and petrochemical industries. Dr. Ezzat holds an MSc degree in
chemical engineering from Washington University and a PhD in petrochemical
applications from Alexandria University. He completed his postgraduate
studies in petroleum processing technologies from the School of Chemical
Engineering at Oklahoma State University.
Hydrocarbon Processing | MAY 2022 41
to fuels with the sun: Issues of
*
O
O
n
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