Hydrocarbon Processing - May 2022 - 39

Special Focus Biofuels, Alternative Fuels and
Green Petrochemicals
A. A. EZZAT, Pharos University, Alexandria, Egypt
CO2
energy recycling approach
in the petrochemical industries
Many industrial processes can generate carbon dioxide (CO2
)
from fossil fuels. Recently, these processes have contributed to an
average annual release of more than 30 Btpy of CO2
into the environment.
From a pre-industrial level of ~270 ppm, the concentration
of CO2
in the atmosphere has now surpassed the 400 ppm
from the environment. FIG. 1 demark,
resulting in today's observed climate change phenomena
and the necessity to recover CO2
picts the average CO2
5 yr. The contribution of the major fuels to these emissions are:
* Natural gas: 23%
* Petroleum: 42%
* Coal: 35%.
To mitigate the CO2
emissions to the atmosphere in the last
However, on an energy level basis, such reactions can be
classified as:
* Reactions that do not require a substantial amount
of external energy. Here, the reaction takes place by
attaching the whole CO2
R2NCOOR3), ureas (RRNCONRR), isocyanates
(RNCO) and carbonates (ROC(O)OR)].
* Reactions that produce reduced forms of CO2
Such reactions are often named as carboxylation
reactions [e.g., the production of carbamates
(R1
. These
impact of fossil oil combustion, carbon
capture and sequestration (CCS) techniques from industrial
plants are being considered and implemented.
The primary processes involve partial CO2
capture, compressing
it for transportation via pipelines, ships, etc., and pumping
it for oil recovery or other limited applications. This requires
increased construction costs, fuel use and utility consumption,
which inevitably produce more pollutants.
Serious concerns have been associated with these uneconomical
processes, which have not solved the environmental problems
posed by CO2
emissions. Therefore, capturing CO2
from
process plants and power generation systems has been recognized
as one of the most promising strategies for reducing CO2
emissions and utilizing CO2
as an alternate carbon source for the
chemical supply chain.
Conversely, growing fuel consumption in developing countries
is continuously increasing CO2
concentrations around
the globe. This means that the traditional reduction routes
are insufficient to mitigate CO2
sible level. TABLE 1 shows the main uses of CO2
industries (in 2019).
Three stages of CO2
concentrations to a permisin
the chemical
utilization developments are considered:
existing mature technologies, such as urea production;
emerging technologies, such as formic acid or other single carbon
(C1
such as electrocatalytic ethylene production.1,2,3,4
reduction
* CO2
insertion
* CO2 condensation
* CO2 addition.
Inorganic carbonate
Methanol
) chemicals manufacture; and innovative explorations,
Basically, CO2
conversion reactions can be summarized as:
* CO2
FIG. 1. The average CO2
emissions in the last 5 yr.
TABLE 1. Main uses of CO2
Process
Urea
in the chemical industries, 2019
Production, tpy
140
75
18
Hydrocarbon Processing | MAY 2022 39
reduction reactions naturally require a considerable
amount of external energy. They include products such
as: HCOO (formates), [C(O)O]2 2e (oxalates),
H2
CO (formaldehyde), etc.
The application of a CO2
recycling approach in modern
petrochemical complexes has shown great potential in the exploitation
of CO2
methanol, ethylene and ethylene oxide) to obtain value-added
products while also contributing to CO2
Greenhouse gas emissions
2% Other gases
7% NOx
13% CH4
78% CO2
recycling reactions from process plants (e.g.,
fixation.
moiety to the other reactant.
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