Mesoporous alumina–zirconia–organosilica composites for CO 2 capture at ambient and elevated temperatures† Chamila Gunathilake and Mietek Jaroniec * New ternary and binary composite mesostructures consisting of alumina, zirconia and organosilica with isocyanurate bridging groups were synthesized via co-condensation of suitable precursors in the presence of a triblock copolymer, Pluronic P123. The resulting binary and ternary composite mesostructures were used for CO 2 capture at low (0  C), ambient (25  C), and elevated (60 and 120  C) temperatures. The CO 2 adsorption capacities measured at 1 atm for alumina–organosilica mesostructures are: 1.43 mmol g 1 at 0  C and 1 mmol g 1 at 25  C. Much higher CO 2 adsorption capacities were recorded at 1 atm for zirconia–organosilica mesostructures: 2.53 mmol g 1 at 0  C and 1.93 mmol g 1 at 25  C. This significant increase in the CO 2 uptake for zirconia–organosilica was achieved due to the development of microporosity, which was shown to be beneficial for CO 2 physisorption at low pressures. Temperature programmed desorption (TPD) was used to measure the CO 2 sorption capacities for the mesostructures studied at 60 and 120  C. The TPD studies revealed the superior sorption capacities of zirconia–organosilica mesostructures at 60  C (3.02 mmol g 1 ) and 120  C (2.76 mmol g 1 ). Various surface hydroxyls present in alumina and zirconia are primarily responsible for CO 2 capture. These hydroxyls were shown to be essential for interactions with CO 2 by forming hydrogen carbonate and bidentate carbonate complexes. The thermal stability, corrosion resistivity, and chemical stability of the mesostructures studied make them attractive sorbents for CO 2 capture in the fossil fuel-based power plants, which generate large volumetric flow rates of flue gas at 1 atm with low partial pressure of CO 2 in the temperature range of 100–150  C. 1. Introduction Accumulation of CO 2 , which is caused by coal burning, volcanic eruptions, forest res, and industrial emissions, is believed to be the major contributor to global warming. The growing concentration of CO 2 may affect the natural climate patterns. For instance, the earth's average temperature has increased by 2 to 4  C, which causes a gradual melting of ice caps and glaciers at north and south poles. Although this change may appear to be a small one, it can induce extreme weather conditions on the earth. Thus, the efficient control of industrial emissions is an emergent demand to mitigate the excessive CO 2 concentration in the atmosphere. The current technology for industrial capture of CO 2 involves its absorption by aqueous solutions of amines, which is known as the amine scrubbing process. 1 However, there are numerous drawbacks in this process such as high energy usage for regeneration of CO 2 and relatively low thermal stability of liquid amines. In addition, this method produces corrosive products and shows lower selectivity for CO 2 in the presence of other gases such as SO 2 , NO 2 , and NO, smaller chemical stability and tolerance to impurities. 2 So, a cost effective CO 2 capture from the ue gas streams of coal- based power plants is indispensable to reduce the CO 2 emis- sions to the atmosphere. The use of solid sorbents for reversible capture of CO 2 from ue gas streams is an attractive alternative to the amine scrubbing process because of its potential advantages such as higher sorption capacity, low energy requirement for regeneration, good selectivity, and easy handling. 3,4 CO 2 capture can be done by using physical or chemical solid sorbents via physical adsorption or chemisorption, respectively. In contrast to physical adsorption systems, the chemisorption- based systems show usually higher CO 2 sorption capacity and better selectivity. Amine-functionalized mesoporous organo- silica materials prepared by using various amine-containing precursors such as 3-aminopropyl-triethoxysilane, N-[3-(trime- thoxysilyl)propyl] ethylene-diamine, (3-trimethoxysilylpropyl) diethylenetriamine, diaminobutane, diaminohexane, dia- minododecane, diethylene triamine, tetraethylenepentamine, and amidoxime have been most oen used for CO 2 capture. 5–11 In general, introduction of basic species into porous solid Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio 44242, USA. E-mail: jaroniec@kent.edu; Fax: +1-330-672-3816; Tel: +1-330-672-3790 † Electronic supplementary information (ESI) available. See DOI: 10.1039/c4ta04677c Cite this: J. Mater. Chem. A, 2015, 3, 2707 Received 9th September 2014 Accepted 4th December 2014 DOI: 10.1039/c4ta04677c www.rsc.org/MaterialsA This journal is © The Royal Society of Chemistry 2015 J. Mater. Chem. A, 2015, 3, 2707–2716 | 2707 Journal of Materials Chemistry A PAPER Published on 04 December 2014. Downloaded by KENT STATE UNIVERSITY on 05/02/2015 17:15:41. View Article Online View Journal | View Issue