Structural chemistry, flexibility, and CO2 adsorption performance of alkali metal forms of merlinoite with a framework Si/Al ratio of 4.2

DOI: 10.1021/acs.jpcc.1c08296

Authors: Elliott L. Bruce (University of St. Andrews) , Veselina M. Georgieva (University of St Andrews) , Maarten C. Verbraeken (University of Edinburgh) , Claire A. Murray (Diamond Light Source) , Ming-Feng Hsieh (Johnson Matthey Technology Centre) , William J. Casteel (Air Products and Chemicals Inc) , Alessandro Turrina (Johnson Matthey Technology Centre) , Stefano Brandani (University of Edinburgh) , Paul A. Wright (University of St Andrews)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C

State: Published (Approved)
Published: December 2021
Diamond Proposal Number(s): 22322

Abstract: Small pore zeolites that show framework flexibility, such as merlinoite (topology type MER), possess a high potential for the selective adsorption of small gas molecules including CO2. The CO2 adsorption properties of Na-, K-, and Cs-exchanged forms of a merlinoite zeolite with Si/Al = 4.2 have been measured at 298 K, and in situ PXRD was used to follow their structural response to dehydration and CO2 uptake. The Na- and Cs-forms convert from a wide-pore to a narrow-pore form upon dehydration, while the K-form remains in the wide-pore form. The Na- and Cs-forms exhibit stepped CO2 adsorption isotherms, consistent with breathing behavior and expansion from narrow- to wide-pore phases, while K6.2-MER remains in the wide-pore structure throughout. Synchrotron PXRD of the K- and Cs-forms reveals the effects of CO2 adsorption on the cation site distributions and the framework configuration. All cation forms of MER (4.2) show enhanced adsorption kinetics for Ar compared to those with lower Si/Al, and the wide-pore structure of K6.2-MER (4.2) shows particularly rapid sorption for both Ar and CO2. Breakthrough curves over K6.2-MER (4.2) demonstrate good separation of CO2 from CH4 in flowing CO2/CH4 mixtures, even in pelletized form with an alumina binder.

Journal Keywords: Adsorption; Diffraction; MERS; Cations; Materials

Diamond Keywords: Gas Separation; Carbon Capture and Storage (CCS)

Subject Areas: Chemistry, Materials, Environment


Instruments: I11-High Resolution Powder Diffraction

Added On: 09/12/2021 15:08

Discipline Tags:

Zeolites Earth Sciences & Environment Climate Change Physical Chemistry Chemistry Materials Science Inorganic Chemistry

Technical Tags:

Diffraction X-ray Powder Diffraction