CO2 Capture using phenoxide salts; alternatives to amine-based capture agents, and comparative speciation studies as components in solvent blends

Abstract

Amine blends represent the leading absorbents for post-combustion CO2 capture, yet they still have considerable issues associated with their use, such as high energy requirements, corrosivity, cost and toxicity. At least one amine component is usually considered to operate as base, and on this hypothesis phenol (pKa 9.95), as its conjugate base, can potentially act as an amine-free alternative in such blends. We report the first detailed study using phenoxide based capture reagents, including different blends of ethanolamine and potassium phenoxide. CO2 absorption rate and speciation of these solutions was compared with that of comparable amine blends, and whilst potassium phenolate alone showed poor kinetics, its use in combination with monoethanolamine (MEA) showed interesting and potentially beneficial properties. This work is the first to use phenoxides as a base in CO2 capture solvents and demonstrates the viability of this diverse family of compounds for industrially relevant CO2 capture solvents.

Zwitterionic “Solutions” for Reversible CO2 Capture

“…The phenolate anion had already been reported as a promising alternative for amine-free CO 2 capture processes or blends. [17] One choice would be the phenolate anion in a simple salt with sodium. However, it is not the best option as volatile and toxic phenol would be formed in the aqueous CO 2 capture.…”

“…Hence, the phenolate group was chosen as the active site, because it is one of the few alternatives to the amino group with basicity in the region of interest. The phenolate anion had already been reported as a promising alternative for amine‐free CO 2 capture processes or blends [17] . One choice would be the phenolate anion in a simple salt with sodium.…”

Efficient Synthesis of Diphenyl Carbonate from CO2, Phenol, and Carbon Tetrachloride under Mild Conditions

“…This result could be rationalized by the fact that different intermediates were formed during the CO 2 activation process such as salicylic acid-like compounds, metal phenoxide–CO 2 complex intermediates, and p -hydroxybenzoic acid-like compounds (Figure S2). , Among these intermediates, salicylic acid-like compounds and metal phenoxide–CO 2 complexes can be transformed to desired products at moderate temperatures, which is an advantage to the improvement of DPC selectivity with increasing temperature up to 100 °C. However, a further increase in the temperature favors the generation of p -hydroxybenzoic acid-like compounds, which can be easily converted into byproducts at higher temperatures, thereby leading to a decline in DPC yield and selectivity.…”

Carbon Capture, Utilisation and Storage as a Defense Tool against Climate Change: Current Developments in West Macedonia (Greece)

“…The CO 2 price on the EU Emissions Trading System (EU ETS), well below 10 €/tCO 2 from 2012 to 2017, is increasing since 2018, reaching the highest ETS price of 51.40 €/tCO 2 on 24 May 2021 [43]. Still, emerging capture technologies are even more promising, with a 40% energy reduction compared to the current ones [44].…”