abstract
Periodic mesoporous organosilicas (PMO), with phenylene or biphenylene organic linkers, were thermally treated in flowing nitrogen atmosphere upon different conditions aiming the enhancement of their CO2 adsorption/separation properties. As-synthesized and template-extracted phenylene-and biphenylene-PMO were pyrolysed at 800 and 1200 degrees C. The effects of: i) the type of organic bridge; ii) the presence of nitrogen atoms; iii) the use of an acid catalyst prior to carbonization; and iv) pore size were investigated. It was found that pyrolysis promotes modifications in the physical-chemical and the textural properties of the PMO materials, being the formation of micropores one of the most notable differences. Furthermore, with the exception of biphenylene-PMO, the molecular-scale periodicity of the materials was strongly affected by the pyrolysis treatment probably as a result of Si-C bond cleavage. The CO2 adsorption capacity and the selectivity for CO2/CH4 separation of all pyrolysed materials were enhanced. In general, the increase of the microporosity in the pyrolysed PMO is accompanied by an improvement of the CO2 adsorption properties with concomitant reduction of the CH4 adsorption behavior. The most interesting material for CO2/CH4 separation is the biphenylene-PMO pyrolysed at 1200 degrees C, with a selectivity of 9.5 at 25 degrees C and 500 kPa. (C) 2017 Elsevier Ltd. All rights reserved.
keywords
MOLECULAR-SCALE PERIODICITY; CARBON-DIOXIDE; ACTIVATED CARBON; POROUS MATERIALS; CO2 ADSORPTION; LANDFILL GAS; DFT CALCULATIONS; METHANE STORAGE; ORGANIC GROUPS; SICO GLASSES
subject category
Chemistry; Materials Science
authors
Lourenco, MAO; Pinto, ML; Pires, J; Gomes, JRB; Ferreira, P
our authors
José R. B. Gomes
Principal Researcher
Mirtha A. O. Lourenço
Researcher
Moisés Luzia Pinto
Research Assistant
Paula Celeste da Silva Ferreira
Coordinating ResearcherGroups
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)
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 | UID/CTM/50011/2013 (CICECO), UID/MULTI/00612/2013 (CQB), UID/ECI/04028/2013 (CERENA), PTDC/EQU-EQU/099423/2008 (FCOMP-01-0124-FEDER-010345), financed by national funds through the FCT/MEC and co-financed by FEDER under the PT2020 Partnership Agreement. The authors are also grateful to FCT Programme Investigator 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 PhD grant SFRH/BD/80883/2011 (to M.A.O.L.) is also acknowledged.