# Direct Air Capture Using Aqueous Amino Acid Solvents in a Crossflow Absorber

## TL;DR

This paper studies using crossflow absorbers with amino acid solvents to capture CO2 from the air more efficiently.

## Contribution

The paper modifies a theoretical model to simulate crossflow DAC absorbers and provides design suggestions for efficient CO2 capture.

## Key findings

- Crossflow absorbers are better for large air and solvent flow rates due to lower pressure drops.
- The modified model helps predict process efficiency based on geometric and operational parameters.
- Design suggestions are provided to improve DAC process efficiency.

## Abstract

Carbon dioxide (CO2) is the most abundant
of all greenhouse
gases (GHGs). CO2 levels in the atmosphere are 50% higher
than in the preindustrial era, trapping heat. CO2 removal
from the atmosphere by direct air capture (DAC) is needed to achieve
the internationally agreed global temperature goals. The most common
CO2 capture technology is absorption by amine-based solvents
in packed columns. Amino acid solutions have recently gained attention
due to their advantages over traditional amine solvents. To be implemented
effectively, DAC industrial processes need to handle large airflow
rates in separation absorbers. The large air and solvent flow rates
preclude the use of countercurrent columns due to high-pressure drops
and the occurrence of flooding. Crossflow air–liquid absorbers
are used to handle large air and liquid volumes due to their lower-pressure
drop. The objective of this work is to study the influence of crossflow
absorber geometric parameters and operating conditions on product
formation and process efficiency. An already derived theoretical model
for countercurrent absorbers has been modified to simulate the operation
of a crossflow DAC absorber. The predictive model was implemented
into a computer code that was used to study the efficiency of the
processes as geometric equipment dimensions and operating parameters
vary. Practical suggestions are made to design more efficient DAC
processes.