How Molecular Modelling Tools Can Help …
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the investigated solvents: increasing the CO 2 partial pressure in the feed stream at
the rich conditions results in an increased cyclic capacity and a decreased regeneration energy [168–170]. In the case of the benchmark solvent, 30 wt% MEA, the
estimated cyclic capacity is in the range 0.26–0.28 moleCO 2 mole amine
-1 (molar
basis) and the associated regeneration energy in the range of 3.5–3.9 GJ tCO 2
−1 , in
very good agreement with those estimated for a MEA-based CO 2 capture plant with
a conventional process configuration from the literature [118, 171, 172].
Interestingly, all the single amine systems examined herein demonstrate lower
regeneration energy than the 30 wt% MEA, used as a benchmark: the lowest estimated
regeneration energy was obtained for 30 wt% MDEA at CO 2 partial pressure of
20 kPa, with a Q regen = 2.3 GJ tCO 2
−1 , and also showing higher cyclic capacity
at the selected conditions. However, in some instances, dependent on the operating
conditions, a trade-off between high molar cyclic capacities and low regeneration
energy exists.
In summary, we have shown here the application of soft-SAFT combined with
limited experimental data, to determine the thermophysical properties of alternative solvents for CO 2 capture, and a preliminary assessment of their performance
at process conditions, as another example of the use of molecular modelling tools
applied to processes to reduce GHG emissions into the atmosphere. With the procedure explained here, the effect of the molecular structure of the amines on the
absorption of CO 2 in aqueous amines and blends can be systematically evaluated
in the search for more efficient solvents for CO 2 capture. This simplified analysis
can steer the selection and development of the most promising alternative single
amine solutions or blends depending on key process parameters such as the solvent
regeneration energy and cyclic capacity. Nevertheless, it is of vital importance to
stress that process operating conditions greatly affect the solvent properties [170] so
more refined calculations should be performed for a specific process.
4.2 Novel Adsorbents for CO 2 Capture
Zeolites and activated carbons have been traditionally used for gas adsorption and
separation. These materials can be fine-tuned depending on the needs of the process,
providing great prospects for CO 2 capture as well. Moreover, over the past decade,
metal-organic frameworks (MOFs) have been rapidly rising as promising materials
for different applications with the number of synthesized structures and publications
increasing exponentially [173]. A large number of studies have examined pure singlecomponent adsorption [174, 175], but multi-component mixture calculations are
scarce in literature [176–179], providing limited data to be used for process design
and integration at industrial conditions. In this regard, computational methods have
become a standard complementary tool to the experimental ones, which can be used
as a screening method at a very moderate computational cost [69].
In this section, a systematic investigation of a selected number of adsorbent materials for CO 2 capture and separation using computational techniques is provided.
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the investigated solvents: increasing the CO 2 partial pressure in the feed stream at
the rich conditions results in an increased cyclic capacity and a decreased regeneration energy [168–170]. In the case of the benchmark solvent, 30 wt% MEA, the
estimated cyclic capacity is in the range 0.26–0.28 moleCO 2 mole amine
-1 (molar
basis) and the associated regeneration energy in the range of 3.5–3.9 GJ tCO 2
−1 , in
very good agreement with those estimated for a MEA-based CO 2 capture plant with
a conventional process configuration from the literature [118, 171, 172].
Interestingly, all the single amine systems examined herein demonstrate lower
regeneration energy than the 30 wt% MEA, used as a benchmark: the lowest estimated
regeneration energy was obtained for 30 wt% MDEA at CO 2 partial pressure of
20 kPa, with a Q regen = 2.3 GJ tCO 2
−1 , and also showing higher cyclic capacity
at the selected conditions. However, in some instances, dependent on the operating
conditions, a trade-off between high molar cyclic capacities and low regeneration
energy exists.
In summary, we have shown here the application of soft-SAFT combined with
limited experimental data, to determine the thermophysical properties of alternative solvents for CO 2 capture, and a preliminary assessment of their performance
at process conditions, as another example of the use of molecular modelling tools
applied to processes to reduce GHG emissions into the atmosphere. With the procedure explained here, the effect of the molecular structure of the amines on the
absorption of CO 2 in aqueous amines and blends can be systematically evaluated
in the search for more efficient solvents for CO 2 capture. This simplified analysis
can steer the selection and development of the most promising alternative single
amine solutions or blends depending on key process parameters such as the solvent
regeneration energy and cyclic capacity. Nevertheless, it is of vital importance to
stress that process operating conditions greatly affect the solvent properties [170] so
more refined calculations should be performed for a specific process.
4.2 Novel Adsorbents for CO 2 Capture
Zeolites and activated carbons have been traditionally used for gas adsorption and
separation. These materials can be fine-tuned depending on the needs of the process,
providing great prospects for CO 2 capture as well. Moreover, over the past decade,
metal-organic frameworks (MOFs) have been rapidly rising as promising materials
for different applications with the number of synthesized structures and publications
increasing exponentially [173]. A large number of studies have examined pure singlecomponent adsorption [174, 175], but multi-component mixture calculations are
scarce in literature [176–179], providing limited data to be used for process design
and integration at industrial conditions. In this regard, computational methods have
become a standard complementary tool to the experimental ones, which can be used
as a screening method at a very moderate computational cost [69].
In this section, a systematic investigation of a selected number of adsorbent materials for CO 2 capture and separation using computational techniques is provided.