Physicochemical properties, equilibrium adsorption performance, manufacturability, and stability of TIFSIX-3-Ni for direct air capture

Abstract

The use of adsorbents for direct air capture (DAC) is regarded as a promising and essential carbon dioxide removal technology to help meet the goals outlined by the 2015 Paris Agreement. A class of adsorbents that has gained significant attention for this application is ultramicroporous metal organic frameworks (MOFs). However, the necessary data needed to facilitate process scale evaluation of these materials is not currently available. Here, we investigate TIFSIX-3-Ni, a previously reported ultramicroporous MOF for direct air capture, and measure several physicochemical and equilibrium adsorption properties. We report its crystal structure, textural properties, thermal stability, specific heat capacity, CO2, N2, and H2O equilibrium adsorption isotherms at multiple temperatures, and Ar and O2 isotherms at a single temperature. For CO2, N2, and H2O, we also report isotherm model fitting parameters and calculate heats of adsorption. We assess the manufacturability and process stability of TIFSIX-3-Ni by investigating the impact of batch reproducibility, binderless pelletization, humidity, and adsorption-desorption cycling (50 cycles) on its crystal structure, textural properties, and CO2 adsorption. For pelletized TIFSIX-3-Ni, we also report its skeletal, pellet, and bed density, total pore volume, and pellet porosity. Overall, our data enable initial process modelling and optimization studies to evaluate TIFSIX-3-Ni for DAC at the process scale. They also highlight the possibility to pelletize TIFSIX-3-Ni and the limited stability of the MOF under humid and oxidative conditions as well as upon multiple adsorption-desorption cycles.

Quantification of temperature-dependent CO2 adsorption kinetics in Lewatit VP OC 1065, Purolite A110, and TIFSIX-3-Ni for direct air capture

“…We also calculated the average equilibrium CO2 loading for the TGA experiments conducted at each temperature (see SI for details). We compared these to the CO2 loadings calculated from the CO2 isotherm fitting model parameters determined from volumetric sorption experiments using a Micromeritics 3Flex porosity analyser discussed in our previous works [51,52]. This analysis helps to verify that the equilibrium results from the TGA are indeed reasonable, and that subsequently the kinetic results which rely on the final equilibrium loading should be reliable as well.…”

“…Lewatit), Purolite A110 (i.e. Purolite), and TIFSIX-3-Ni, as we previously highlighted these materials as promising adsorbents for DAC and reported many of their physicochemical and equilibrium sorption properties [51,52]. In terms of their CO2 adsorption kinetics, no data is currently available for Purolite and TIFSIX 0.04%vol) CO2 balanced with N2 using a thermogravimetric analyser.…”