resumo
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.
palavras-chave
MOLECULAR-SCALE PERIODICITY; CARBON-DIOXIDE; ACTIVATED CARBON; POROUS MATERIALS; CO2 ADSORPTION; LANDFILL GAS; DFT CALCULATIONS; METHANE STORAGE; ORGANIC GROUPS; SICO GLASSES
categoria
Chemistry; Materials Science
autores
Lourenco, MAO; Pinto, ML; Pires, J; Gomes, JRB; Ferreira, P
nossos autores
José R. B. Gomes
Investigador Principal
Mirtha A. O. Lourenço
Investigador
Moisés Luzia Pinto
Investigador auxiliar
Paula Celeste da Silva Ferreira
Investigador CoordenadorGrupos
G1 - Materiais Porosos e Nanossistemas
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G6 - Materiais Virtuais e Inteligência Artificial
Projectos
CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)
RMNE-UA-National Network of Electron Microscopy (REDE/1509/RME/2005 )
agradecimentos
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.