Work

Enhanced CO2 capture rate and capacity through alkylation of polyethylenimines forming a microphase separation structure

Year: 2025

Type: article

Abstract: Among organic amines, polyethylenimines (PEIs) have been widely utilized to functionalize various porous solid sorbents to capture CO 2 , aiming to mitigate global warming. However, low CO 2 capacity (due to limited CO 2 diffusion) and CO 2 -induced amine degradation hinder their commercialization. In this study, we developed a series of alkyl (C 4 to C 12 ) grafted PEIs. The optimized specimen, 1:9-C 12 -25kPEI, in which 1 in 9 amine groups are alkylated with C 12 alkyl chains (PEI backbone M n = 25k Da), demonstrated much higher CO 2 capacity (180 mg CO 2 per 1 g PEI) compared with the control specimen 25kPEI (10 mg CO 2 per 1 g PEI) at ambient temperature and pressure (14 °C and 100 % CO 2 ), with a 0.21-mm thick liquid specimen layer. The corresponding half capacity times ( t 0.5 ) of the specimens were 8.8 and 43.7 s, respectively. The improved capture kinetics is due to the formation of a microphase separation structure in the alkylated PEI, where the continuous alkyl-dominated phase facilitates CO 2 diffusion into the bulk (about 70 μm in depth) to access amine groups in PEI-dominated nanodots (about 13 nm in diameter). Moreover, the rapid CO 2 capture consumes free amine groups quickly, avoiding CO 2 -induced amine degradation in consecutive absorption-desorption cycles at 65 and 95 °C. The alkylated PEIs possess a strong capability to capture CO 2 , insensitive to capture temperature (14–65 °C) and the mesoporous structure of solid supports. They are suitable for capturing CO 2 across a wide temperature range and at various CO 2 partial pressures (from air to post-combustion flue gases).

Source: Journal of CO2 Utilization

DOI: 10.1016/j.jcou.2025.103292

Authors: Yuanzhu Long, Yuanzhe Yan, Hairong Yue, Xingyi Xie

Institutions: Zunyi Medical University, Sichuan University

Language: English

Topic: Carbon Dioxide Capture Technologies

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Climate action, Responsible consumption and production

Open Access status: gold

Estimated APC paid: $3,360