New Metrics of Green Sorbents for CO₂Capturing

Abstract

Significant progress has been made in the past decades in the capture, storage, and utilization of greenhouse gases, particularly CO2. In general, the synthesis of most of the available CO2 sorbents is not ecofriendly and can require multistep synthesis in order to prepare and/or activate, which is considered a strict violation of green chemistry principles (GCPs). Therefore, thinking of green frameworks to design chemical products and processes becomes essential to mitigate these challenges. This paper provides an in‐depth review of available green sorbents for CO2 capture with an emphasis on those prepared from biorenewable materials and ionic liquids. A new metric is presented to classify these sorbents based on their degree of compliance to the GCPs, which could be a useful tool in selection of green alternatives. Due to the interdisciplinary nature of this research topic, a wide range of literature is available in multiple areas including but not limited to chemistry and engineering. Hence, this review targets a wide range of scientists including chemists, biotechnologists, material scientists, and meteorologists, as well as green industrial corporations.

Toward the Proactive Design of Sustainable Chemicals: Ionic Liquids as a Prime Example

“…The rising viscosity within this process (up to 240-fold for P666-14 isoleucinate) is a major obstacle, as it is accompanied by increased process expenses, e.g . for pumping, and reduced CO 2 uptake rates . Ether groups in the side chains were able to reduce the viscosity issue for pyridinium ILs.…”

“…ILs have been suggested as absorbents in carbon dioxide capture and sequestration (CCS), for example for the retrofitting of coal-fired power plants, as several ILs exhibit high CO 2 solubility and selectivity with respect to other flue gases such as N 2 , CO, CH 4 , ethylene, or argon. , …”

“…Common ILs bind CO 2 by nonstoichiometric physisorption. , CO 2 solubility depends predominantly on the structure of the IL anion, since the interaction with the cation is far weaker. , Bulky and, in particular, highly fluorinated anions perform best (Figure ). , The different cation head groups do not lead to significantly different CO 2 solubilities, as Tf 2 N ILs of imidazolium, pyridinium, pyrrolidinium, as well as quaternary phosphonium and ammonium show comparable results. , Only choline performed slightly worse and the availability of an acidic proton at the C-2 position of the imidazolium cation was reported to marginally increase CO 2 solubility, , as were long alkyl side chains and fluorination. ,− …”

“…ILs have been suggested as absorbents in carbon dioxide capture and sequestration (CCS), for example for the retrofitting of coalfired power plants, as several ILs exhibit high CO 2 solubility and selectivity with respect to other flue gases such as N 2 , CO, CH 4 , ethylene, or argon. 150,151 Common ILs bind CO 2 by nonstoichiometric physisorption. 47,150 CO 2 solubility depends predominantly on the structure of the IL anion, since the interaction with the cation is far weaker.…”

“…150,151 Common ILs bind CO 2 by nonstoichiometric physisorption. 47,150 CO 2 solubility depends predominantly on the structure of the IL anion, since the interaction with the cation is far weaker. 152,153 Bulky and, in particular, highly fluorinated anions perform best (Figure 4).…”