608
The CO 2 capture from air is very challenging because of thermodynamic limitations
resulting from the awfully low CO 2 concentrations and the energy cost for driving
large volumes of air through a capturing process. Hence the CO 2 separation processes like cryogenic distillation and membrane separation are not economically
viable. During the past several years, enormous contributions have been devoted
through different approaches for CO 2 capture from the ambient air [57].
Alkaline solution-based technologies are well investigated and incorporating the
chemisorption approach via. LiOH/NaOH/KOH/Ca(OH) 2 scrubbing to produce
metal carbonates with CO 2 . The produced metal carbonate solution is recycled back
to the hydroxide-based solution to establish a cyclic process. The captured CO 2 can
be further sequestered or utilized as C1 chemical feedstocks [58].
Traditional solid sorbent materials were also attempted to capture CO 2 from
ambient air. Among the solid adsorbents, the activated carbon and zeolite materials
which are well-known for post-combustion/pre-combustion CO 2 capture are not
found efficient for capture from ambient air. This is due moisture existing in atmosphere leading to poor selectivity towards CO 2 in air [59]. Hence, the emerging
technologies for CO 2 capture from stationary point source are economically more
worthwhile when compared to atmospheric carbon capture [60].
2.6 Technologies on Carbon Dioxide Conversion to Chemicals
and Fuels from Various Sources
The CO 2 technologies have the great impact on the reduced usage of fossil fuels
towards energy materials. Although this is the eco-friendly carbon source existing
in the atmosphere, the suitable methodology will be useful to achieve the valueadded materials. The Table 1 describes the diverse value-added chemicals that are
derived on industrial scale using thermo-, electro-, and photochemical and biological methods. The commercially existing technologies on CO 2 utilization will be
described in this section in brief [61–63].
2.6.1 Polycarbonate
The Asahi Kasei Corporation (Japan) has established the synthetic methodology
for aromatic polycarbonate using CO 2 for the first time. In the earlier days, the usage
of phosgene or diphenyl carbonate is used for the synthesis of polyaromatic carbonate. The carbonate in polycarbonate links directly to the residual aromatic rings of
the bisphenol. This process being clean technology does not require any purification
process and produces no waste or by-products. Followed by this, several plants are
built with license agreement in South Korea, Russia, and Saudi Arabia. A total of
around six companies are involved in the production of polycarbonate using this
technology with 1.07 million tons/year by consuming 0.185 million tons of CO 2
per annum [62, 63].
R. Arunachalam et al.
The CO 2 capture from air is very challenging because of thermodynamic limitations
resulting from the awfully low CO 2 concentrations and the energy cost for driving
large volumes of air through a capturing process. Hence the CO 2 separation processes like cryogenic distillation and membrane separation are not economically
viable. During the past several years, enormous contributions have been devoted
through different approaches for CO 2 capture from the ambient air [57].
Alkaline solution-based technologies are well investigated and incorporating the
chemisorption approach via. LiOH/NaOH/KOH/Ca(OH) 2 scrubbing to produce
metal carbonates with CO 2 . The produced metal carbonate solution is recycled back
to the hydroxide-based solution to establish a cyclic process. The captured CO 2 can
be further sequestered or utilized as C1 chemical feedstocks [58].
Traditional solid sorbent materials were also attempted to capture CO 2 from
ambient air. Among the solid adsorbents, the activated carbon and zeolite materials
which are well-known for post-combustion/pre-combustion CO 2 capture are not
found efficient for capture from ambient air. This is due moisture existing in atmosphere leading to poor selectivity towards CO 2 in air [59]. Hence, the emerging
technologies for CO 2 capture from stationary point source are economically more
worthwhile when compared to atmospheric carbon capture [60].
2.6 Technologies on Carbon Dioxide Conversion to Chemicals
and Fuels from Various Sources
The CO 2 technologies have the great impact on the reduced usage of fossil fuels
towards energy materials. Although this is the eco-friendly carbon source existing
in the atmosphere, the suitable methodology will be useful to achieve the valueadded materials. The Table 1 describes the diverse value-added chemicals that are
derived on industrial scale using thermo-, electro-, and photochemical and biological methods. The commercially existing technologies on CO 2 utilization will be
described in this section in brief [61–63].
2.6.1 Polycarbonate
The Asahi Kasei Corporation (Japan) has established the synthetic methodology
for aromatic polycarbonate using CO 2 for the first time. In the earlier days, the usage
of phosgene or diphenyl carbonate is used for the synthesis of polyaromatic carbonate. The carbonate in polycarbonate links directly to the residual aromatic rings of
the bisphenol. This process being clean technology does not require any purification
process and produces no waste or by-products. Followed by this, several plants are
built with license agreement in South Korea, Russia, and Saudi Arabia. A total of
around six companies are involved in the production of polycarbonate using this
technology with 1.07 million tons/year by consuming 0.185 million tons of CO 2
per annum [62, 63].
R. Arunachalam et al.