Please cite this article in press as: D. Wang, et al., Three-dimensional molecular basket sorbents for CO 2 capture: Effects of pore structure of supports and loading level of polyethylenimine, Catal. Today (2014), http://dx.doi.org/10.1016/j.cattod.2014.01.038 ARTICLE IN PRESS G Model CATTOD-8886; No. of Pages 8 Catalysis Today xxx (2014) xxx–xxx Contents lists available at ScienceDirect Catalysis Today j our na l ho me page: www.elsevier.com/locate/cattod Three-dimensional molecular basket sorbents for CO 2 capture: Effects of pore structure of supports and loading level of polyethylenimine Dongxiang Wang a,b , Xiaoxing Wang a , Xiaoliang Ma a,c , Eric Fillerup a , Chunshan Song a,b,∗ a Clean Fuels and Catalysis Program, EMS Energy Institute and Department of Energy and Mineral Engineering, Pennsylvania State University, 209 Academic Projects Building, University Park, PA 16802, USA b National Energy Technology Laboratory-Regional University Alliance (NETL-RUA), United States Department of Energy, Pittsburgh, PA, USA c Current Address: Petroleum Research Center, Kuwait Institute for Scientific Research, P.O. Box 24885, Safat 13109, Kuwait a r t i c l e i n f o Article history: Received 11 October 2013 Received in revised form 9 January 2014 Accepted 23 January 2014 Available online xxx Keywords: CO2 capture Molecular basket sorbent 3-D support Mesoporous molecular sieve Polyethylenimine Sorption a b s t r a c t Three-dimensional (3-D) mesoporous materials including mesocellular siliceous foam (MCF), MSU-J and hexagonal mesoporous silica (HMS) were examined as supports of “molecular basket” sorbents (3-D MBS) by loading CO 2 -philic polyethylenimine (PEI). The CO 2 sorption performance of the 3-D MBS was evaluated in comparison with the MBS by using MCM-41, SBA-15 and carbon black (CB) as the supports. The effect of PEI loading on the sorption capacity is associated with the sorption temperature and pore structure of the support. At 30 wt% PEI loading, the increase in temperature from 30 to 75 ◦ C has a slight and even negative effect on the sorption capacity; while at 65 wt% PEI loading, it has a significant, positive effect. Superior CO 2 sorption capacity and sorption rate of 3-D MBS over 2-D and 1-D MBS were observed. MCF-based MBS with 65 wt% PEI loading (PEI(65)/MCF) gave the highest CO 2 sorption capacity of 201 mg- CO 2 /g-sorb. The maximum PEI loading for MCF was up to 80 wt%, which is the largest among the support materials studied in this work, and is related to its largest pore volume. The highest sorption capacity and sorption rate of PEI(65)/MCF are ascribed to its largest pore size and unique 3-D pore structure, which facilitate the CO 2 diffusion, promote mass transfer and offer more accessible sorption sites. The present work demonstrates that the 3-D mesoporous solid amine sorbents are more effective for CO 2 capture in comparison with 1-D and 2-D materials in terms of higher sorption capacity and faster sorption rate. The pore structure (pore dimension, pore size, pore volume) of the support, PEI loading and temperature are the three key factors that determine the sorption capacity and sorption rate. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Increase of CO 2 concentration in Earth’s atmosphere, which has been linked to the global climate change, has become a press- ing environmental concern [1–4]. A great deal of effort has been devoted to controlling the emission of CO 2 to the atmosphere, and carbon capture and sequestration (CCS) has been considered as one of the key strategies to mitigate CO 2 emissions. Development of CO 2 capture/separation technologies with minimal energy penalty has become a major global challenge [5,6]. The amine functionalized solid sorbents through grafting or impregnation of amine-based oligomers or polymers on porous supports have shown to be effec- tive and less-energy-intensive, as they overcome some significant disadvantages of using aqueous amine solution directly in amine ∗ Corresponding author at: EMS Energy Institute and Department of Energy & Min- eral Engineering, Clean Fuels and Catalysis Program, 209 Academic Projects Building, University Park, PA 16802, USA. Tel.: +1 8148634466; fax: +1 8148653248, 8148653573. E-mail addresses: csong@psu.edu, hoscxs@gmail.com (C. Song). scrubbing process [1,7,8]. In the last 10 years, our laboratory has been working on development of the solid amine sorbents, called “molecular basket” sorbents (MBS), for CO 2 capture by loading CO 2 - philic polymer/oligomer on mesoporous molecular sieves [8,9]. Many studies on the basis of this concept have been conducted and reported, and the results indicate that there are several advan- tages in using the solid amine sorbents over the conventional amine scrubbing, including higher capacity, high selectivity, high gas–sorbent interface, fast sorption/desorption rate, no or less cor- rosion problem, good regenerability and stability, and lower energy consumption for regeneration [10,11]. A wide variety of mesoporous silica materials, such as MCM-41 [8,9], SBA-15 [12], SBA-12 [13], SBA-16, KIT-6, MCM-48 [14], hexag- onal mesoporous silica (HMS) [15], and mesocellular siliceous foam (MCF) [16] have been used for preparation of the amine sorbents for CO 2 sorption. The first generation of MBS developed in our labora- tory by loading 50 wt% PEI on one dimensional (1-D), well ordered MCM-41, exhibited a CO 2 sorption capacity of 90 mg-CO 2 /g-sorb [8,9]. By impregnation of 50 wt% PEI on two dimensional (2- D), well ordered SBA-15, an improved CO 2 sorption capacity of 0920-5861/$ – see front matter © 2014 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cattod.2014.01.038