Interfacial Insights into a Carbon Capture System: CO₂ Uptake to an Aqueous Monoethanolamine Surface

Abstract

Monoethanolamine (MEA) is a benchmark scrubber for CO gas emissions reductions. Preliminary studies have indicated surface monoethanolamine could influence the greater chemistry of CO uptake. MEA is known to be surface active and orients at aqueous surfaces such that its nitrogen lone pair electrons are pointing toward the gas phase. This MEA orientation has the potential to facilitate CO surface chemistry; however, a thorough description of the chemistry at play during this important carbon capture reaction is lacking. These studies investigate the surface behavior of MEA during CO gas flow, monitoring product formation and species migration. A combination of experimental vibrational sum frequency spectroscopy (VSFS), surface tensiometry, molecular dynamics simulations, and density functional calculations are used to investigate this complex chemistry. CO is shown to react with MEA, perturbing the interface and leading to the presence of carbamic acid in the surface region. However, throughout this chemistry the surface remains largely populated by unreacted MEA. These studies provide insight into this important carbon capture reaction and provide a framework for future work examining interfacial reactions and dynamics.

On the Rise: Experimental and Computational Vibrational Sum Frequency Spectroscopy Studies of Pyruvic Acid and Its Surface-Active Oligomer Species at the Air–Water Interface

“…Vibrational sum frequency (VSF) spectroscopy is an inherently surface-selective nonlinear optical technique that provides a vibrational spectrum of surface-active molecules that are anisotropically ordered and noncentrosymmetric. − At asymmetric interfaces, VSF spectroscopy is a well-established technique that has been used extensively by the Richmond lab ,− and others − to study liquid interfaces. By overlapping a fixed visible and a tunable-frequency IR beam in time and space, a third sum frequency beam is generated, which is the sum of the incident frequencies.…”

“…These techniques also provide vital structural and behavioral insights about the simulated system, such as depth-dependent molecular partitioning. This approach has been shown to be robust, efficient, and highly adaptable for numerous and varied chemical systems when compared with experimental spectra. ,− …”

“…Molecular dynamics (MD) simulations are performed using the Amber 12 suite of programs using parameters and force fields derived in the same manner as in previous studies, ,− and starting configurations were generated by PACKMOL . In each simulation, a specific number of PA and water molecules are arranged to form a 30 Å cube within a 30 Å × 120 Å × 30 Å simulation box, with periodic boundary conditions, forming a water slab with two interfaces.…”

Unraveling the Structure and Binding Energy of Adsorbed CO2/H2O on Amine Sorbents

“…Amine-based sorbents have been considered the preferred material for the CO 2 capture process in the presence of H 2 O because of their high selectivity and capture capacity for CO 2 , rapid kinetics for adsorption/desorption, and long-term regeneration capacity. With the materials development of amine-based sorbents, efforts have been directed toward investigating the H 2 O–CO 2 –amine interactions using both experimental and first-principle theoretical calculation approaches to understand CO 2 uptake on porous polymers, aqueous surfaces, ionic liquids, , metal organic framework (MOF), − and solid-supported amine sorbents. − CO 2 adsorption over supported amine sorbents has been studied under two general experimental conditions: the dry CO 2 capture (eqs and ) in a water vapor free environment , and wet CO 2 adsorption (eqs –) in the presence of 4–6% water vapor. , …”

Improving CO2/CH4 and CO2/N2 adsorptive selectivity of Cu‐BTC and MOF‐derived nanoporous carbon by modification with nitrogen‐containing groups

“…2 During the past few decades, chemical absorption process using aqueous solution of alkanolamines such as monoethanolamine (MEA), diglycol-amine (DGA), 2-amino-2-methyl-1-ethanolamine (DEA), and N-methyldiethanolamine (MDEA) with its propanol (AMP) has been commercially applied for CO 2 capture. 3 However, despite its wide commercial use, this method has several disadvantages such as high regeneration costs, equipment corrosion and solvent degradation in the presence of oxygen. 4 Among the gas separation techniques, adsorption-based separation has become a key gas separation tool in industry owing to its inherent simplicity, ease of control, low cost, and high energy efficiency.…”