Page 1
Registered Charity Number 207890
Accepted Manuscript
This is an Accepted Manuscript, which has been through the RSC Publishing peer review process and has been accepted for publication.
Accepted Manuscripts are published online shortly after acceptance, which is prior to technical editing, formatting and proof reading. This free service from RSC Publishing allows authors to make their results available to the community, in citable form, before publication of the edited article. This Accepted Manuscript will be replaced by the edited and formatted Advance Article as soon as this is available.
To cite this manuscript please use its permanent Digital Object Identifier (DOI®), which is identical for all formats of publication.
More information about Accepted Manuscripts can be found in the Information for Authors.
Please note that technical editing may introduce minor changes to the text and/or graphics contained in the manuscript submitted by the author(s) which may alter content, and that the standard Terms & Conditions and the ethical guidelines that apply to the journal are still applicable. In no event shall the RSC be held responsible for any errors or omissions in these Accepted Manuscript manuscripts or any consequences arising from the use of any information contained in them.
www.rsc.org/ees
ISSN 1754-5692
Energy&Environmental Science
COVER ARTICLEDrain et al.Commercially viable porphyrinoid dyes for solar cells
REVIEWHofmann and SchellnhuberOcean acidifi cation: a millennial challenge 1754-5692(2010)3:12;1-G
www.rsc.org/ees Volume 3 | Number 12 | December 2010 | Pages 1813–2020
Volume 3 | N
umber 12 | 2010
Energy & Environm
ental Science
Pages 1813–2020
www.rsc.org/publishingRegistered Charity Number 207890
Dank u wel kiitos takk fyrir
aitäh děkuji D’akujem БлагодаряСпасибо Thank you Tak
grazie Takk Tack 唔該 Danke
Merci gracias Ευχαριστω
どうもありがとうございます。
As a result of your commitment and support, RSC journals have a reputation for the highest quality content. Your expertise as a referee is invaluable – thank you.
To our referees:
Energy &Environmental Science
View Article OnlineView Journal
Page 2
1
Carbon Nanotube Modified Carbon Composite Monoliths as Superior Adsorbents for
Carbon Dioxide Capture†
Yonggang Jin,a Stephen C. Hawkins,b Chi P. Huynhb and Shi Su*a
aCSIRO Earth Science and Resource Engineering, PO Box 883, Kenmore, Qld 4069, Australia
bCSIRO Materials Science and Engineering, PMB 10, Clayton, Victoria 3168, Australia
*Correspondence should be addressed to Dr. Shi Su. Email: [email protected] ; Tel: +61-7-
33274679; Fax: +61-7-33274455
† Electronic supplementary information (ESI) available.
Page 1 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 3
2
Table of contents entry
Incorporating a small proportion of carbon nanotubes significantly improves pore structures and
CO2 adsorption properties of carbon composite monoliths.
Page 2 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 4
3
Broader context
Growing concerns for global warming and climate changes have attracted widespread efforts to
develop efficient and cost-effective technologies for post-combustion CO2 capture (PCC) from
large point sources, such as coal-fired power plants. CO2 capture using porous solid sorbents
constitutes a promising solution. Among them, porous carbons are particularly suited to the PCC
application owing to their abundant microporosity, ease of fabrication and excellent chemical,
thermal and mechanical stability. However, achieving acceptable adsorption capacity from this
low CO2 partial pressure stream (typically 10-15% CO2 in the flue gas) remains a challenge.
Approaches to improving CO2 uptake of porous carbons have focused on chemical activation and
functionalization with basic groups. These methods have disadvantages such as greater
complexity and cost, and difficult regeneration of adsorbents. Here we report a simple and low-
cost method of preparing carbon composite monoliths from a commercial phenolic resin mixed
with just 1 wt% of carbon nanotubes (CNTs), followed by carbonization and physical activation
with CO2. The products possess a hierarchical macroporous-microporous structure exhibiting
superior CO2 adsorption capacity and kinetics, and excellent CO2/N2 selectivity. This work may
also pave the way for the more general use of CNTs to develop hierarchically porous structured
composites for energy and environmental applications.
Page 3 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 5
4
Abstract
Carbon composite monoliths were prepared from a commercial phenolic resin mixed with just 1
wt% of carbon nanotubes (CNTs) followed by carbonization and physical activation with CO2.
The products possess a hierarchical macroporous-microporous structure and superior CO2
adsorption properties. In particular, they show the top-ranked CO2 capacity (52 mg CO2 g-1
adsorbent at 25 oC and 114 mmHg) under low CO2 partial pressures that is of more relevance for
flue gas applications, matching or exceeding those of carbons produced by complex chemical
activation and functionalization. This study demonstrates an effective way to create narrow
micropores through structural modification of carbon composites by CNTs.
Keyword: Porous Carbon, Carbon Nanotube, Composite, CO2 Capture, Adsorption
Page 4 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 6
5
Post-combustion capture of carbon dioxide using porous solid sorbents is showing great promise
in reducing anthropogenic CO2 emissions from point sources such as coal-fired power plants.1-19
A variety of porous solids such as metal-organic frameworks,5-8 covalent organic frameworks,9
zeolites,10 porous carbons,11-18 and amine-functionalized silicas19 have been extensively
investigated. Carbon materials have advantages such as low cost and high chemical, thermal and
mechanical stability necessary to operate in realistic flue gas streams, which contain in addition
to CO2, N2 and O2, NOx, SOx, steam and dust. Porous carbons have been produced since antiquity
by charring coal and biomass or more recently from pitch, resin and other polymers. Although
they may be moderately adsorbent as formed, they can be further activated physically (physical
activation) by etching with oxidative gases e.g. CO2 and steam at high temperatures,12,20 or
chemically (chemical activation) by blending carbon precursors with a large quantity of
chemicals e.g. KOH and ZnCl followed by pyrolysis.14,21
Although chemically activated carbons have been reported to exhibit large microporosities and
superior CO2 adsorption capacity,11,14 there is a high cost, waste and inconvenience with this
method as chemical residues must be thoroughly washed out after pyrolysis. Another approach to
improving CO2 adsorption capacity of porous carbons has focused on functionalization with basic
groups such as doping nitrogen,15-17 or loading amine.18 However, this method also has greater
complexity or cost, and some of functionalized carbons show difficult and unstable regeneration
of adsorbents due to strong interaction with CO2.
Physical activation is simpler, more economic and cleaner but generally produces carbons with
lower CO2 adsorption capacity. Moreover, it requires the penetration of oxidative gases from
outside the structure especially when preparing monolithic adsorbents so that initially formed
Page 5 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 7
6
surface pores are widened excessively before the interior structure is accessed. Some
improvement in accessibility has been achieved by costly or complex approaches of, for example,
synthesizing porous precursor resins,22,23 or forming interconnected micrometer voids between
primary resin particles by partial curing of phenolic resins, subsequent milling and particle
classification.24
Here we present a simple and cost-effective way to fabricate physically activated carbon
composite monoliths (CCMs) with superior CO2 sorption properties. A commercial phenolic
resin was used as the carbon precursor and structurally modified by incorporating a small
proportion (CNT/resin=1 wt%) of carbon nanotubes (CNTs) to provide an open nanoscale
scaffold. This aims to distribute and support the resin as it is cured and carbonized so that a
uniform meso/macroporous structure could be formed to allow easy access for physical activation.
Initial CCM studies used multiwall CNTs grown in-house by a catalyst pre-deposition (CPD)
process which produces catalyst-free, highly aligned, straight and relatively easily dispersed
CNTs as a forest on a silicon or quartz substrate.25 The obtained CPD CNTs were typically of 10
nm in diameter and 300 µm in length as displayed in the scanning electron microscopy (SEM)
image (Fig. S1†). The as-grown CPD CNTs were acid-treated to make them hydrophilic and fully
dispersed and after washing to pH = 7 adjusted to a 1 wt% dispersion in an aqueous gel solution
containing 2 wt% of methyl cellulose (MC). The resulting CNT hydrogel paste was highly stable
and prevented clumping of CNTs during storage and processing. CCMs were prepared by
thoroughly mixing a given amount of commercial phenolic resin powder with the CNT hydrogel
paste and adding additional MC (2 wt%) gel to make a smooth stiff paste typically comprising
resin, CNTs, MC and H2O in the ratio of 100:1:6:300, respectively. After molding, drying and
curing the mixture, the composite monolith was carbonized in nitrogen and activated with CO2
Page 6 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 8
7
for a range of times to achieve different levels of burn-off (i.e. weight loss arising from
activation). The activated CPD CCMs were labeled as CPD-x, where x=15, 30 and 45 are the
activation durations in minutes. For comparison, monolith samples without CNTs were prepared
and labeled as Res-60 and ResG-60, denoting 60 min activation time. The former was made of
phenolic resin alone and the latter contained MC gel at the same level as the CPD CCM sample.
As seen from the photography (Fig. S2†), the CCM was molded into a honeycomb monolith
around 2 cm in diameter and 7 cm long with five 2 mm diameter channels. The purpose behind
the honeycomb design is to improve the flow resistance and pressure drop as well as reduce
clogging when dealing with dusty flue gas streams.
CNT-modified CCM samples are much more reactive with CO2 during activation, exhibiting
significant burn-off within a much shorter activation duration. 16.7 wt% of burn-off was achieved
for the CPD CCM sample (CPD-15) in just 15 min, whereas resin alone (Res-60) or with gel
(ResG-60) took 60 min to reach 7.6 and 15 wt%, respectively (Table 1). All these samples show a
type-I N2 sorption isotherm (Fig. 1a), typical for microporous materials.26 Surface areas (SBET)
increase from CPD-15 to CPD-45 with an increase of burn-off, and are 3-7 folds greater than for
Res-60 (Table 1). CO2 equilibrium adsorption capacity at different CO2 partial pressures can be
obtained from CO2 adsorption isotherms. The values of both molar (mmol g-1) and mass (mg g-1)
capacity were reported in this work representing mmol and mg of CO2 adsorbed per g of
adsorbent, respectively. From CO2 adsorption isotherms of activated samples at 298 K (Fig. 1b),
the CO2 uptake at 1 atm (denoted as C100) of CPD CCMs peaks at 3.48 mmol g-1 (153 mg g-1),
about 1.9 times the CO2 amount adsorbed by Res-60 (1.86 mmol g-1, 82 mg g-1) and over twice
that of a typical commercial bituminous coal-derived activated carbon, GC-C30 (1.58 mmol g-1,
70 mg g-1). As the flue gas is typically only 10-15% CO2, the CO2 amount adsorbed at a low CO2
Page 7 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 9
8
partial pressure (pCO2) presents a more realistic estimate of performance. The CO2 uptake at 298
K and 114 mmHg (corresponding to 15% pCO2), denoted as C15, was defined as an indicator of
low-pressure CO2 adsorption capacity (Fig. 1b & Table 1). Whereas CPD-30 gives the highest
C100 value, CPD-15 has the highest C15 at 49 mg g-1, more than twice that of resin alone Res-60
(24 mg g-1). The C15 of CPD CCMs diminishes with extended activation, falling to 35 mg g-1 for
CPD-45.
To gain further insights of CO2 adsorption, from their CO2 adsorption isotherms at 273 K (Fig.
1c) the narrow micropore (<1nm) size distributions (NMPSDs) of adsorbents (Fig. 1d) were
obtained with the density function theory (DFT) model.27 Corresponding surface areas (Snm) and
pore volumes (Vnm) are listed in Table 1. It is evident that the activated phenolic resin alone (Res-
60) has considerably less micropore development than CNT-modified CCMs with lower values
in Snm and Vnm. CPD-15 exhibits the largest microporosity in the pore size range of 0.55±0.15 nm.
In comparison, CPD-30 presents a decreased proportion of micropores smaller than 0.6 nm but an
increased number of micropores larger than 0.6 nm, consequently yielding a lower C15 but a
higher C100. A further increase in burn-off, as observed in CPD-45, results in a decrease of Snm
and Vnm, and in particular a significant loss of micropores smaller than 0.6 nm. Hence CPD-45
has a much reduced C15 (35 mg g-1). These results show that CO2 adsorption capacity of
adsorbents is determined by the development of narrow microporosity in terms of the volume of
narrow micropores (Vnm) and their pore size distributions, which depends heavily on activation.
CNT-modified CCMs can be activated remarkably rapidly, allowing an extensive formation of
micropores with minimal widening that usually occurs during extended activation. In addition to
high CO2 uptakes, CO2 sorption of CNT-modified CCMs is completely reversible and no
significant hysteresis was observed in Fig. S3†.
Page 8 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 10
9
The primary aim of the MC hydrogel was to facilitate dispersion and mixing of composite
components. As noted above, simply including MC with the resin but without CNTs improves
burn-off from 7.6 (Res-60) to 15.0 wt% (ResG-60) with better sorption characteristics and pore
development (Fig. 1a-d & Table 1). However, the rate of activation is still very low and the
obtained CO2 adsorption capacity is only moderate compared with CPD CCMs. The MC
hydrogel could help to generate pores during carbonization, which would favor activation by
facilitating the access of CO2. However, by dramatically hastening activation, CNTs play the
dominant role in improving pore structures and CO2 capacity of CNT-modified CCMs.
SEM (Fig. 2a,b) revealed that CNT-modified CCMs (CPD-15) possess an interconnected
macroporous structure formed by resin-derived carbons spread over and between CNTs.
Transmission electron microscopy on CPD-15 confirmed that CNTs are embedded in the carbon
material (Fig. S4†). By contrast, the activated resin Res-60 exhibits only macroscopic vapor holes
(Fig. S5†). Mercury porosimetry of the carbonized CPD CCM and resin samples prior to
activation (Fig. 2c) shows that CNTs promote significant pore formation at 0.1-1.5 µm and 10-
100 µm scales in carbonized CCMs. The absence of mesopores in both carbonized samples was
confirmed by their N2 sorption (Fig. S6†) which exhibits no hysteresis between p/p0 of 0.4-0.85.
The geometry of CNT-modified CCMs provides both easy access of activation agent to the
monolith’s interior and a large primary surface area by distributing resins into micro/nanometer
scale domains thus providing more locations for rapidly creating a large population of narrow
micropores. To rule out any effects on activation from Fe catalyst possibly associated with CNTs,
thermogravimetric analysis on the acid-treated CPD CNT was carried out in air and gave no
residue (Fig. S7†).
Page 9 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 11
10
To study the effects of CNT characteristics on CO2 adsorption, CCMs were also prepared using
multiwall CNTs with different specifications to the CPD variety. These comprised aligned CNTs
produced in-house by a catalyst co-injection process (designated CCI, ~80 nm diameter, ~1500
µm length, lightly branched and tangled)28 and a commercial product (designated Com) which is
10-20 nm diameter, 5-15 µm length and very densely tangled as received (Fig. S1†). These CNT
samples were acid treated and dispersed in 2 wt% MC as for CPD CNTs prior to preparing
CCMs, designated CCI-x and Com-x as described above. CCI-15 and Com-15 were found to
burn off even more rapidly than CPD-15, reaching 23.0 and 20.2 wt%, compared with 16.7 wt%
for CPD-15, respectively during activation for 15 min (Table 1). As a result, CO2 uptakes at 298
K are slightly higher than those of CPD CCMs. In particular, CCI-30 exhibits the highest C100 at
159 mg g-1, whilst CCI-15 and Com-15 achieve the highest C15 at 52 mg g-1 (Fig. 3a and Table 1).
As with CPD CCMs, the NMPSDs of CCI and Com CCMs (Fig. 3b) were obtained from their
CO2 adsorption isotherms at 273 K (Fig. S8†) and agree well with CO2 adsorption capacity at
different pCO2.
Although our physically activated CCMs have a lower C100 (159 mg g-1) than some chemically
activated carbons with the highest ever reported C100 of 212 mg g-1,14 of more relevance for flue
gas applications is the C15 value. Our CNT-modified CCMs reach a C15 value of 52 mg g-1,
higher than those of chemically activated carbons, and matching or exceeding those of N-doped
carbons (see Table S1† for comparisons of CO2 adsorption capacity for porous carbons).11,13-17,29-
34 To the best of our knowledge, our CCMs exhibit the highest CO2 uptakes both for C100 and C15
ever measured for porous carbons prepared by physical activation.
Page 10 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 12
11
The isosteric heat of CO2 adsorption for Com-15, calculated from CO2 adsorption isotherms at
273, 298 and 323 K (Fig. S9a†), is 32.6 kJ mol-1 at near zero loading and declines to 27.1 kJ mol-
1 at 2 mmol g-1 of CO2 adsorbed (Fig. S9b†). The heat of adsorption at low surface coverage
indicates the interaction between the adsorbent and adsorptive molecules, relying on the pore size
and surface chemistry of the adsorbent. The value for Com-15 (32.6 kJ mol-1) is higher than for
other pristine porous carbons (20-30 kJ mol-1)14,35,36 and comparable to those of mildly N-doped
porous carbons16,17. Considering the nature of sample precursors and high temperature treatment
at 950 oC, we believe that the observed CO2 uptake of the prepared CCM adsorbents is due to
physisorption; that is, CO2 molecules are physisorbed into micropores. The higher heat of
adsorption than those of other pristine porous carbons can be attributed to the well-developed
narrow microporosity of Com-15 as very narrow micropores give rise to increased adsorbate-
adsorbent interactions. However, compared to zeolites and some heavily N-doped porous carbons
(36-50 kJ mol-1),10,37 the heat of adsorption for Com-15 is low, suggesting easy CO2 desorption
during regeneration of the adsorbent. We further calculated the selectivity of CO2 over N2 for
Com-15 at 273 and 298 K using the ratios of the Henry’s law constants (Fig. S10†) estimated
from the initial slopes of CO2 and N2 adsorption isotherms at 273 and 298 K (Fig. 4a). The
calculated CO2/N2 selectivity at 273 K is 32.6 and at 298 K is 19.8, substantially higher than that
of recently reported porous carbons (~7),38,39 implying excellent selectivity for CO2 adsorption.
In addition to a reversible and high CO2 uptake and excellent CO2/N2 selectivity, a fast
adsorption kinetic is one of the necessary properties for an effective adsorbent material. The rates
of CO2 adsorption on the activated resin alone, with gel and CNT-modified CCM samples were
compared at 298 K and 25 mmHg (Fig. 4b). CO2 uptake on Com-15 is completed within 40 s,
whereas for ResG-60 adsorption reaches only 98% at 150 s while even after 300 s Res-60 reaches
Page 11 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 13
12
just 92%. The slow adsorption kinetics of the latter samples is attributed to deep tortuous
micropores resulting from extended activation in contrast to the numerous and shallow
micropores achieved by rapid activation of Com-15 and other CNT-modified CCMs, thanks to a
hierarchical macroporous-microporous structure that supports rapid transport of gas molecules
into the monolith.
The diameter, length or state of dispersion of CNTs has a bearing on the structure and properties
of new CNT-modified CCMs and it is anticipated that a better understanding of this will lead to a
further improvement in their performance. Remarkably, however, the superior adsorption
capacity demonstrated by Com-15 makes the newly developed CCMs very promising for large-
scale deployment and commercial applications to carbon capture when considering that such a
small amount of CNT addition is required and the commercial CNTs can be manufactured cost-
effectively in high volumes.
In summary, we have demonstrated a simple and low-cost method of preparing CCMs with
superior CO2 adsorption properties. The products possess a hierarchical macroporous-
microporous structure exhibiting exceptional CO2 adsorption capacity and kinetics, and excellent
selectivity for CO2 over N2. The approach developed in the study may also pave the way for the
more general use of CNTs to develop hierarchically porous structured materials for applications
that require favorable mass transport, such as catalysis, separation, energy storage and conversion.
Page 12 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 14
13
Acknowledgements
This project is funded by CSIRO. The authors would like to acknowledge Ms Lynne Waddington
of CSIRO Materials Science and Engineering for her help with TEM imaging and the Melbourne
Centre for Nanofabrication for the use of their SEM.
References
1 A. Samanta, A. Zhao, G.K.H. Shimizu, P. Sarkar and R. Gupta, Ind. Eng. Chem. Res., 2012,
51, 1438-1463.
2 A. Sayari, Y. Belmabkhout and R. Serna-Guerrero, Chem. Eng. J., 2011, 171, 760-774.
3 Q.Wang, J. Luo, Z. Zhong and A. Borgna, Energy Environ. Sci., 2011, 4, 42-55.
4 D.M. D’Alessandro, B. Smit and J.R. Long, Angew. Chem. Int. Ed., 2010, 49, 6058-6082.
5 K. Sumida, D.L. Rogow, J.A. Mason, T.M. McDonald, E.D. Bloch, Z.R. Herm, T.H. Bae and
J.R. Long, Chem. Rev., 2012, 11, 724-781.
6 B. Wang, A.P. Côté, H. Furukawa, M. O’Keeffe and O.M. Yaghi, Nature, 2008, 453, 207-
211.
7 S.H. Yang, X. Lin, W. Lewis, M. Suyetin, E. Bichoutskaia, J.E. Parker, C.C. Tang, D.R.
Allan, P.J. Rizkallah, P. Hubberstey, N.R. Champness, K.M. Thomas, A.J. Blake and M.
Schroder, Nature Mater., 2012, 11, 710-716.
8 R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa, M. O'Keeffe and O.M. Yaghi,
Science, 2008, 319, 939-943.
9 P. Mohanty, L.D. Kull and K. Landskron, Nature Comm., 2011, 2, 401.
10 K.T. Cheu, J.N. Kim, Y.J. Yoo, S.H. Cho and R.T. Yang, Ind. Eng. Chem. Res., 1995, 34,
591-598.
Page 13 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 15
14
11 J. Silvestre-Albero, A. Wahby, A. Sepulveda-Escribano, M. Martinez-Escandell, K. Kaneko
and F. Rodriguez-Reinoso, Chem. Commun., 2011, 47, 6840-6842.
12 R. Thiruvenkatachari, S. Su, H. An and X.X. Yu, Prog. Energy Combust. Sci., 2009, 35, 438-
455.
13 G.P. Hao, W.C. Li, D. Qian, G.H. Wang, W.P. Zhang, T. Zhang, A.Q. Wang, F. Schuth, H.J.
Bongard and A.H. Lu, J. Am. Chem. Soc., 2011,133, 11378-11388.
14 M. Sevilla, A.B. Fuertes, Energy Environ. Sci., 2011, 4, 1765-1771.
15 G.P. Hao, W.C. Li, D. Qian and A.H. Lu, Adv. Mater., 2010, 22, 853-857.
16 M. Sevilla, P. Valle-Vigon and A.B. Fuertes, Adv. Funct. Mater., 2011, 21, 2781-2787.
17 Y.D. Xia, R. Mokaya, G.S. Walker and Y.Q. Zhu, Adv. Energy Mater., 2011, 1, 678-683.
18 L. Zhao, Z. Bacsik, N. Hedin, W. Wei, Y.H. Sun, M. Antonietti and M.M. Titirici,
ChemSusChem, 2010, 3, 840-845.
19 C. Chen, S.T. Yang, W.S. Ahn and R. Ryoo, Chem. Commun., 2009, 24, 3627-3629.
20 J.P. Marco-Lozar, M. Kunowsky, F. Suzrez-Garcia, J.D. Carruthers and A. Linares-Solano,
Energy Environ. Sci., 2012, 5, 9833-9842.
21 Z.R. Yue, C.L. Mangun and J. Economy, Carbon, 2002, 40, 1181-1191.
22 V.M. Gun’ko, O.P. Kozynchenko, W. Turov, S.R. Tennison, V.I. Zarko, Y.M. Nychiporuk,
T.V. Kulik, B.B. Palyanytsya, V.D. Osovskii, Y.G. Ptushinskii and A.V. Turov, Colloid Surf.
A-Physicochem. Eng. Asp., 2008, 317, 377-387.
23 Y. Meng, D. Gu, F.Q. Zhang, Y.F. Shi, L. Cheng, D. Feng, Z.X. Wu, Z.X. Chen, Y. Wan, A.
Stein and D.Y. Zhao, Chem. Mater., 2006, 18, 4447-4464.
24 S.R. Tennison, Appl. Catal. A-Gen., 1998, 173, 289-311.
25 C.P. Huynh and S.C. Hawkins, Carbon, 2010, 48, 1105-1115.
Page 14 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 16
15
26 J. Silvestre-Albero, A. Silvestre-Albero, F. Rodriguez-Reinoso and M. Thommes, Carbon,
2012, 50, 3218-3133.
27 A.V. Neimark, Y. Lin, P.I. Ravikovitch and M. Thommes, Carbon, 2009, 47, 1617-1628.
28 S.C. Hawkins, J.M. Poole and C.P. Huynh, J. Phys. Chem. C, 2009, 113, 12976-12982.
29 E.S. Kikkinides, R.T. Yang and S.H. Cho, Ind. Eng. Chem. Res., 1993, 32, 2714-2720.
30 R.V. Sirivardane, M.S. Shen, E.P. Fisher and J.A. Poston, Energy Fuels, 2001, 15, 279-284.
31 C.F. Martin, M.G. Plaza, S. Garcia, J.J. Pis, F. Rubiera and C. Pevida, Fuel, 2011, 90, 2064-
2072.
32 M.G. Plaza, S. Garćia, F. Rubiera, J.J. Pis and C. Pevida, Sep. Purif. Technol., 2011, 80, 96-
104.
33 M. Sevilla and A.B. Fuertes, J. Colloid Interface Sci., 2012, 366, 147-154.
34 L.Y. Meng and S.J. Park, J. Colloid Interface Sci., 2010, 352, 498-503.
35 S. Himeno, T. Komatsu and S. Fujita, J. Chem. Eng. Data, 2005, 50, 369-376.
36 C.R. Reid and K.M. Thomas, Langmuir, 1999, 15, 3206-3218.
37 L.F. Wang and R.T. Yang, J. Phys. Chem. C, 2012, 116, 1099-1106.
38 J.D. Carruthers, M.A. Petruska, E.A. Sturm and S.M. Wilson, Microporous Mesoporous
Mater., 2012, 154, 62-67.
39 C. Ducrot-Boisgontier, J. Parmentier, A. Faour, J. Patarin and G.D. Pirngruber, Energy Fuels,
2010, 24, 3595-3602.
Page 15 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 17
16
Fig. 1 (a) N2 sorption isotherms at 77K for activated samples Res-60, ResG-60, CPD-15, CPD-30
and CPD-45. (b) CO2 adsorption isotherms at 298K for these samples and the pelletized
commercial activated carbon GC-C30. (c) CO2 adsorption isotherms at 273 K. (d) Narrow
micropore (<1nm) size distributions (NMPSDs). Symbols in (c) and (d) are the same as in (b).
0.0 0.2 0.4 0.6 0.8 1.00
100
200
300
400
500
Adsorption Desorption
CPD-45
CPD-30
Ads
orbe
d vo
lum
e (c
m3 g
-1 S
TP
)
Relative pressure p/p0
Res-60
ResG-60
CPD-15
100 200 300 400 500 600 700 8000.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5 Res-60 ResG-60 CPD-15 CPD-30 CPD-45 GC-C30
Ads
orbe
d am
ount
(m
mol
g-1)
Absolute pressure (mmHg)
0 100 200 300 400 500 600 700 8000
1
2
3
4
5
6
Ads
orbe
d am
ount
(m
mol
g-1)
Absolute pressure (mmHg)
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Por
e si
ze d
istr
ibut
ion
(cm
3 g-1 n
m-1)
Pore size (nm)
(a) (b)
(c) (d)
Page 16 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 18
Fig. 2 Morphology and macropore size distributions:
porosimetry for the carbonized phenolic resin and the carbonized CPD composite prior to
activation.
(a)
(b)
17
Morphology and macropore size distributions: (a,b) SEM images of CPD
for the carbonized phenolic resin and the carbonized CPD composite prior to
11010010000.0
0.5
1.0
1.5
2.0
Phenolic resin CPD composite
Cum
ulat
ive
pore
vol
ume
(cm
3 g-1)
Mercury pore size (µm)
(c)
SEM images of CPD-15. (c) Mercury
for the carbonized phenolic resin and the carbonized CPD composite prior to
0.010.1
Phenolic resin CPD composite
m)
Page 17 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 19
18
Fig. 3 (a) CO2 adsorption isotherms at 298 K for CPD-15, CCI-15, CCI-30 and Com-15;
expansion of plot below 120 mmHg (inset). (b) NMPSDs of these samples. Symbols in (b) are
the same as in (a).
100 200 300 400 500 600 700 8000.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5 CPD-15 CCI-15 CCI-30 Com-15
0 20 40 60 80 100 1200.0
0.2
0.4
0.6
0.8
1.0
1.2
Ads
orbe
d am
ount
(m
mol
g-1)
Absolute pressure (mmHg)
Ads
orbe
d am
ount
(m
mol
g-1)
Absolute pressure (mmHg)
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Pore size (nm)
Por
e si
ze d
istr
ibut
ion
(cm
3 g-1 n
m-1)(a) (b)
Page 18 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 20
19
Fig. 4 (a) CO2 and N2 adsorption isotherms for Com-15 at 273 and 298 K. (b) Rates of CO2
adsorption for Res-60, ResG-60 and Com-15 at 298 K and 25 mmHg.
0 100 200 300 400 500 600 700 8000
1
2
3
4
5
CO2-273K
CO2-298K
N2-273K
Am
ount
ads
orbe
d (m
mol
g-1)
Absolute pressure (mmHg)
N2-298K
0 50 100 150 200 250 3000
20
40
60
80
100
Res-60 ResG-60 Com-15
Ads
orpt
ion
com
plet
ed (
%)
Time (s)
(b) (a)
Page 19 of 20 Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
Page 21
20
Table 1 Physical characteristics of activated adsorbents Samples Burn-off
(wt%) N2 adsorption at 77K CO2 adsorption at 273K CO2 uptake (mg g-1)
SBET [a] (m2 g-1)
Vt [b] (cm3 g-1)
Vm [c] (cm3 g-1)
Snm [d] (m2 g-1)
Vnm [d] (cm3 g-1)
298K 1atm, C100
298K, 114 mmHg, C15
273K 1atm
Res-60 7.6 237 0.108 0.107 317 0.092 82 24 121 ResG-60 15.0 625 0.277 0.277 477 0.140 122 40 179 CPD-15 16.7 857 0.384 0.376 591 0.177 146 49 220 CPD-30 25.5 1085 0.489 0.481 551 0.168 153 46 238 CPD-45 54.0 1777 0.804 0.786 412 0.128 145 35 243 CCI-15 23.0 825 0.371 0.363 604 0.179 150 52 220 CCI-30 30.2 1033 0.470 0.456 604 0.184 159 49 245 Com-15 20.2 831 0.370 0.367 623 0.185 152 52 226
[a] SBET: specific surface area calculated by the Brunauer-Emmett-Teller (BET) method (p/p0=0.05-0.15); [b] Vt: total pore volume at p/p0≈0.99; [c] Vm: micropore volume calculated by the Dubinin-Radushkevich (DR) equation; [d] Snm and Vnm: the surface area and volume of narrow micropore (<1nm) calculated with the DFT model,27 respectively.
Page 20 of 20Energy & Environmental Science
En
erg
y &
En
viro
nm
enta
l Sci
ence
Acc
epte
d M
anu
scri
pt
Dow
nloa
ded
by N
atio
nal C
heng
Kun
g U
nive
rsity
on
05 M
arch
201
3Pu
blis
hed
on 0
1 M
arch
201
3 on
http
://pu
bs.r
sc.o
rg |
doi:1
0.10
39/C
3EE
2444
1E
View Article Online
