Changes in Porous Parameters of the Ion Exchanged X Zeolite and Their Effect on CO2 Adsorption.

Andżelika Gęsikiewicz-Puchalska,Antoni W Morawski,Agnieszka Kałamaga,Urszula Narkiewicz,Michal Zgrzebnicki,Rafal Wrobel,Beata Michalkiewicz

doi:10.3390/molecules26247520

Andżelika Gęsikiewicz-Puchalska, Antoni W Morawski + Show 5 more

Open Access

https://doi.org/10.3390/molecules26247520

Copy DOI

Abstract

Zeolite 13X (NaX) was modified through ion-exchange with alkali and alkaline earth metal cations. The degree of ion exchange was thoroughly characterized with ICP, EDS and XRF methods. The new method of EDS data evaluation for zeolites was presented. It delivers the same reliable results as more complicated, expensive, time consuming and hazardous ICP approach. The highest adsorption capacities at 273 K and 0.95 bar were achieved for materials containing the alkali metals in the following order K < Na < Li, respectively, 4.54, 5.55 and 5.94 mmol/g. It was found that it is associated with the porous parameters of the ion-exchanged samples. The Li0.61Na0.39X form of zeolite exhibited the highest specific surface area of 624 m2/g and micropore volume of 0.35 cm3/g compared to sodium form 569 m2/g and 0.30 cm3/g, respectively. The increase of CO2 uptake is not related with deterioration of CO2 selectivity. At room temperature, the CO2 vs. N2 selectivity remains at a very high stable level prior and after ion exchange in co-adsorption process (XCO2 during adsorption 0.15; XCO2 during desorption 0.95) within measurement uncertainty. Additionally, the Li0.61Na0.39X sample was proven to be stable in the aging adsorption-desorption tests (200 sorption-desorption cycles; circa 11 days of continuous process) exhibiting the CO2 uptake decrease of about 6%. The exchange with alkaline earth metals (Mg, Ca) led to a significant decrease of SSA and micropore volume which correlated with lower CO2 adsorption capacities. Interestingly, the divalent cations cause formation of mesopores, due to the relaxation of lattice strains.

Highlights

The emission of carbon dioxide into the atmosphere from fossil fuel combustion is considered as a major source of intensifying of the greenhouse effect [1,2]
A few general methods are being used to CO2 capture from flue gas, including absorption, adsorption, cryogenic processes and membrane separation [5,6,7,8]
One can obtain the substitution of sodium cations by other ions in the framework of zeolite

Summary

Introduction

The emission of carbon dioxide into the atmosphere from fossil fuel combustion is considered as a major source of intensifying of the greenhouse effect [1,2]. Anthropogenic methane is a more potent greenhouse gas than CO2, its lower emission provides the second-largest contribution to global warming [3,4]. The extensive discussion about complex impact of anthropogenic CO2 on environment, descriptions of major threats, critical counterarguments, etc. A few general methods are being used to CO2 capture from flue gas, including absorption, adsorption, cryogenic processes and membrane separation [5,6,7,8]. Adsorption with solid sorbents followed by underground storage, so-called carbon capture and storage (CCS), is one of the most promising options to reduce CO2 emission [9]. Different types of porous materials, such as activated carbons, molecular sieves, metal-organic frameworks and zeolites, could be used as CO2 adsorbents [10,11,12,13]

Methods

Results

Conclusion