Imagine that one could capture CO2 using a smart magnet - The CARBOMAG project is based on a novel concept for CO2 capture combining nanotechnology with magnetic separation in a multidisciplinary approach. The new development is expected to result in more than 50% cost reduction compared to today's CO2 capture processes.
The concept is based on a standard process for post-combustion CO2 capture using absorption and amine solvents. The main difference is related to the regeneration part of the process. The separation of CO2 from flue gas is first provided through sorption on functionalized magnetic nanoparticles dispersed in water in a regular absorber. The CO2-rich nanoparticles are thereafter separated from the bulk solution outside the absorber by means of a magnetic field and then subsequently regenerated, in which CO2 is released. The cleaned particles are finally re-mixed with bulk liquid and recycled into the absorber. The main focus in the project will be to 1) develop nanoparticles that can bind CO2 satisfactorily and have magnetic properties to enable magnetic separation of the particles from the liquid and 2) to develop a process including magnetic separation of these nanoparticles.
It is expected that the project will result in the following improvements relative to the presently used amine process:
- The amount of solvent to be regenerated is much smaller implying significant reduction of the heat requirement and use of smaller units in the regeneration part and thus a decrease of the capital cost
- Due to negligible volatility of the nano-solvents, lower atmospheric emission from the CARBOMAG process is expected, and money saved as no countermeasures against emissions are required.
In order to select most promising systems for CO2 capture, a molecular simulation model has been developed, which can be tailored to a specific system. The model need to be further improved to investigate reaction energies for a range of solvents in order to predict behaviour of the different systems as CO2 capture agents and recommend most promising systems for synthesis and testing. A number of samples have been synthesized based on Funzionano® technology, developed at SINTEF MK earlier through a number of research projects. The synthesized nano-solvents were incorporated with different magnetic particles using two techniques:
1. surface modification of synthesized magnetic particles with CO2 active sites
2. incorporation of commercially available magnetic particles into a sol-gel network of nano-solvents.
It has been proved, that magnetic particles can be part of a hybrid network capable of CO2 capture, and can drag this network with magnetism before and after CO2 capture. However, experimental tests on the CO2 uptake rate and capacity shown that although CO2 reacts with the active groups present in the CARBOMAG samples, the solvents were not able to absorb large amount of CO2. The main challenge was in preparing samples with high concentration of magnetic hybrid nanoparticles evenly dispersed in the liquid phase avoiding coagulation. Even though it was obvious that magnetic separation is possible, the synthesis procedures need to be further improved.
A simplified model of the magnetic separation unit has been implemented in the in-house tool CO2SIM and an initial study of the heat requirement in the total process has been done. Based on assumptions that solvent performance is similar to 30 wt% MEA, simulations of CARBOMAG process shows potential of energy reduction by 29%. An interesting and important finding is that flow split ratio after the absorber seems to have larger effect on energy consumption than concentration of active sites in the solution. This gives an important feedback for the solvent development.
This proposal presents a new concept for CO2 separation involving sorption on functionalized magnetic nanoparticles followed by magnetic separation of the CO2-rich nanoparticles from the bulk solution outside the absorber, and a subsequent regeneration of the particles with CO2 release. After turning off the magnetic field, the cleaned particles are then re-mixed with bulk liquid and recycled into the absorber. At the core of the project is the development of 1) nanoparticles that can bind CO2 with controllable thermodynamics and fast kinetics, and that have magnetic properties to enable magnetic separation of the particles from the liquid, and 2) a total process including magnetic separation to use the aforementioned particles. If successful, the project will result in the following improvements relatively to the presently used amine process:
Large savings in energy consumption, as the solvent volume to be regenerated becomes much smaller
Reduction of capital costs, since the stripper vessel can be made much smaller
Reduction of atmospheric emission from the process itself, as the nanoparticle-based sorbent has no measurable vapour pressure and may further be kept under control by virtue of their magnetic properties.
CLIMIT-Forskning, utvikling og demo av CO2-håndtering