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

abstract

Nonfunctionalized and functionalized periodic mesoporous phenylene-silicas (Ph-PMOs) with different kinds of amine groups were prepared and their capacity to uptake CO2 and CH4 molecules were experimentally evaluated considering biogas upgrading. It was found that aminopropyl groups grafted to the free silanols of the Ph-PMO displayed the highest selectivity for CO2 gas, adsorbing 26.1 times more CO2 than CH4 at 25 degrees C. The interaction effect of the surface of these materials with the CO2 or CH4 molecules was obtained through the calculation of the Henry constants, and the adsorption mechanisms involved were elucidated from density functional theory calculations. The good synergy between experimental gas adsorption and computational studies suggests that the latter can be used to guide the experimental synthesis of more effective materials. Thus, our computational studies were extended to PMOs with other functional groups having different polarity for predicting interaction energies with CO2 and thus identifying the most promising candidates for experimental synthesis.

keywords

TOTAL-ENERGY CALCULATIONS; WAVE BASIS-SET; CHEMICAL-MODIFICATION; POROUS MATERIALS; ORGANIC GROUPS; LANDFILL GAS; WALLS; ADSORBENTS; SURFACE; METALS

subject category

Chemistry; Science & Technology - Other Topics; Materials Science

authors

Lourenco, MAO; Siquet, C; Sardo, M; Mafra, L; Pires, J; Jorge, M; Pinto, ML; Ferreira, P; Gomes, JRB

Groups

G1 - Porous Materials and Nanosystems
G2 - Photonic, Electronic and Magnetic Materials
G6 - Virtual Materials and Artificial Intelligence

Projects

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)

Intelligent design of mesoporous organosilicas for adsorptive separation processes (PTDC/EQU-EQU/099423/2008)

RMNE-UA-National Network of Electron Microscopy (REDE/1509/RME/2005 )

acknowledgements

This work was developed in the scope of the Projects POCI-01-0145-FEDER-007679 vertical bar UID/CTM/50011/2013 (CICECO), UID/MULTI/00612/2013 (CQB), UID/ECI/04028/2013 (CERENA), NORTE-07-0124-FEDER-000011 vertical bar UID/EQU/500230/2013 (LSRE-LCM), PTDC/EQU-EQU/099423/2008 (FCOMP-01-0124-FEDER-010345), financed by national funds through the FCT/MEC and cofinanced by FEDER under the PT2020 Partnership Agreement. The authors are also grateful to FCT Programmes Ciencia 2007 and Investigador FCT, to the Portuguese NMR Network (RNRMN), and to the National Network of Electron Microscopy and University of Aveiro: Project REDE/1509/RME/2005. The Ph.D. Grant SFRH/BD/80883/2011 (to M.A.O.L.) and Postdoc Grant SFRH/BPD/65978/2009 (to M.S.) are also acknowledged. Umberto Martinez and Gianfranco Pacchioni are acknowledged for kindly providing the structure of p-phenylenesilica corresponding to a sequence of six and four member rings with T³ to T² ratio 2:1. The authors are also indebted to Joao Santos for fruitful discussions.