Dynamic structural and microstructural responses of a metal–organic framework type material to carbon dioxide under dual gas flow and supercritical conditions

Abstract

The structural and microstructural responses of a model metal–organic framework material, Ni(3-methyl-4,4′-bipyridine)[Ni(CN)4] (Ni-BpyMe or PICNIC-21), to CO2 adsorption and desorption are reported for in situ small-angle X-ray scattering and X-ray diffraction measurements under different gas pressure conditions for two technologically important cases. These conditions are single or dual gas flow (CO2 with N2, CH4 or H2 at sub-critical CO2 partial pressures and ambient temperatures) and supercritical CO2 (with static pressures and temperatures adjusted to explore the gas, liquid and supercritical fluid regimes on the CO2 phase diagram). The experimental results are compared with density functional theory calculations that seek to predict where CO2 and other gas molecules are accommodated within the sorbent structure as a function of gas pressure conditions, and hence the degree of swelling and contraction in the associated structure spacings and void spaces. These predictions illustrate the insights that can be gained concerning how such sorbents can be designed or modified to optimize the desired gas sorption properties relevant to enhanced gas recovery or to addressing carbon dioxide reduction through carbon mitigation, or even direct air capture of CO2.

Selected advances in small-angle scattering and applications they serve in manufacturing, energy and climate change

“…In several studies of the 'PICNIC' family of MOF-like materials (Allen et al, 2015(Allen et al, , 1991(Allen et al, , 2023, the microstructure and structure have been characterized by SAXS or SANS under single and dual gas conditions, as well as under highpressure static CO 2 conditions. Fig.…”

Crystal structure and synchrotron X-ray powder reference pattern for the porous pillared cyanonickelate, Ni(3-amino-4,4′-bipyridine)[Ni(CN)4]

“…The size of the pores of the materials can be modified by the lengths of the pillared ligands. We have reported a number of PICNIC compounds previously (Wong-Ng et al, 2013, 2016a, 2016b, 2018, 2021a, 2021bAllen et al, 2015Allen et al, , 2019Allen et al, , 2023Wong-Ng, 2018;Lawson et al, 2019;Cockayne et al, 2021).…”

Carbonation reactions and performance of cements, minerals and sustainable materials

“…In this connection, it is recognized that CDR must be achieved not only with overall net CO2 reduction, but also with acceptable product performance when new processing is involved. We also recognize reliable determination of CO2 sequestration in carbonation and mineralization reactions to need density functional theory (DFT) and other computer simulations already employed for CO2 sorbents [3,4], including in DAC.…”