Branched versus Linear Structure: Lowering the CO2 Desorption Temperature of Polyethylenimine-Functionalized Silica Adsorbents

Abstract

Lowering the regeneration temperature for solid CO2-capture materials is one of the critical tasks for economizing CO2-capturing processes. Based on reported pKa values and nucleophilicity, we compared two different polyethylenimines (PEIs): branched PEI (BPEI) and linear PEI (LPEI). LPEI outperformed BPEI in terms of adsorption and desorption properties. Because LPEI is a solid below 73–75 °C, even a high loading amount of LPEI can effectively adsorb CO2 without diffusive barriers. Temperature-programmed desorption (TPD) demonstrated that the desorption peak top dropped to 50.8 °C for LPEI, compared to 78.0 °C for BPEI. We also revisited the classical adsorption model of CO2 on secondary amines by using in situ modulation excitation IR spectroscopy, and proposed a new adsorption configuration, R1(R2)-NCOOH. Even though LPEI is more expensive than BPEI, considering the long-term operation of a CO2-capturing system, the low regeneration temperature makes LPEI attractive for industrial applications.

Data‐Driven Analysis of Amine‐Based Sorbents for CO2 Removal from the Atmosphere

“…This can be due to the higher concentration of primary amines, which have higher amine efficiency for CO 2 capture [69]. Another reason can lie in the higher accessibility of the amine groups on these linear polymers, making them more exposed to CO 2 molecules due to the absence of complex carbon branches and tertiary amine groups which are only active in CO 2 adsorption in the presence of moisture [70,71]. Another important observation is the very high amine efficiency of APTES.…”

Distribution and Mobility of Amines Confined in Porous Silica Supports Assessed via Neutron Scattering, NMR, and MD Simulations: Impacts on CO2 Sorption Kinetics and Capacities

“…While researchers have systematically altered key structural aspects of the support such as average support pore diameter, support pore volume and support channel length and particle size, − limited insight is available regarding the structure and dynamics of the supported, low MW branched PEI phase. Some empirical knowledge has been gathered correlating CO 2 uptake behavior to the structure of aminopolymers with varied structures (e.g., branched vs linear, MW, grafted PEI), − but little is known about how these polymers fill the pores or move within the pores. To address this gap, we employed techniques from the soft matter community to investigate supported amine adsorbents with the goal of directly probing the polymer domains in these composite materials.…”

Automated Parameterization of Coarse-Grained Polyethylenimine under a Martini Framework

“…Polyethylenimine (PEI) is a versatile polymer useful in many applications, including nanofiltration, , carbon capture, , fuel cells, , solar cells, , biosensing, , and gene therapy. , Each application requires different properties like molecular weight (MW), dispersity (the ratio between weight average MW ( M w ) and number average MW ( M n )), degree of branching (DB), and protonation ratio (PR). For example, it is desirable to have PEIs with high M w and DB for nanofiltration, linear PEIs for carbon capture, and PEIs with moderate M w , and DB for gene therapy. Therefore, identifying the structure–function relationship of PEI is crucial for optimizing its performance.…”