Insights into CO₂ and CH₄ Adsorption by Pristine and Aromatic Amine-Modified Periodic Mesoporous Phenylene-Silicas

Abstract

This version is available at https://strathprints.strath.ac.uk/56714/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the AbstractThe synthesis and characterization of pristine and amine-functionalized periodic mesoporous phenylene-silicas having different pore sizes are reported. We explore the potential of these materials for CO2/CH4 separation, by studying the adsorption of pure CO2and pure CH4 gases. The aminated periodic mesoporous phenylene-silica with the smallest pore size is the best adsorbent to CO2, presenting a Henry's constant of 0.56 mol kg -1 ·bar -1 at 35 ºC. However, the corresponding Henry's constant for CH4 is extremely low (0.06 mol·kg -1 ·bar -1 at 35 ºC). It is observed a direct correlation between the % of T 2 SMP silanols species and the values of the Henry's constants, which may be used to theoretically predict experimental CO2 Henry's constants of potential adsorbents.3

Interaction of CO2 and CH4 with Functionalized Periodic Mesoporous Phenylene–Silica: Periodic DFT Calculations and Gas Adsorption Measurements

“…Recently, we described and understood the amination of the Ph-PMO (NH2-Ph-PMO) with different pore sizes (2.4 -3.7 nm) and tested their performance on the CO2 and CH4 adsorption. 16 We observed that the CO2 affinity on these materials can be directly correlated to the amount of T 2 free silanols and the amination on the phenylene moieties is only effective on materials with small pore size, improving the affinity to the CO2 gas. In the present work, non-functionalized (Ph-PMO) and amine functionalized Ph-PMOs (NH2-Ph-PMO), having pore sizes of approximately 2.5 nm, were synthesized according to previously reported procedures.…”

Selectivity for CO2 over CH4 on a functionalized periodic mesoporous phenylene-silica explained by transition state theory

“…Thus far, selectivity for CO 2 /CH 4 separation for different functionalized PMOs has been evaluated by using experiments [30,31], while the CO 2 and CH 4 adsorption mechanisms involved in this materials were clarified using periodic density functional theory (DFT) calculations [30]. In fact, as we have observed, experimental gas adsorption data and computational studies are in good agreement and such DFT results proved also useful to guide the preparation of more efficient PMO materials.…”

“…Additionally, Ph-PMOs display a narrow distribution of both meso-and molecular-scale periodicities; a clear advantage for adsorbate diffusion within the pore channels. Moreover, we have seen [30,31] that the modification of the Ph-PMO with amine groups allows the optimization of their properties for the separation of CO 2 /CH 4 , by improving the interaction with the CO 2 molecule. Recently, we demonstrated that aminopropyl groups grafted to the free silanols of Ph-PMO promote selectivity for CO 2 /CH 4 separation making the resulting APTMS@Ph-PMO so far the most selective of all PMOs applied in this field, at 25 °C adsorbing 26.1 times more CO 2 than CH 4 , as determined by the ratio of Henry constants [30].…”

Recent Advances in the Preparation and Applications of Organo‐functionalized Porous Materials

“…demonstrated that amine groups could be functionalized in the PMOs through mononitration with nitric acid in the presence of sulphuric acid, followed by the reduction with tin chloride and HCl. The amine‐functionalized samples showed higher selectivity for the adsorption of CO 2 molecules in comparison with the CH 4 molecules . The same group also manipulated the amine‐functionalized PMOs for the formation of dialkylated amine through the microwave‐assisted approach.…”