U.S. patent application number 15/229566 was filed with the patent office on 2016-11-24 for activated carbon-metal organic framework composite materials with enhanced gas adsorption capacity and process for the preparation thereof.
The applicant listed for this patent is Bharat Petroleum Corporation Limited, Council of Scientific & Industrial Research. Invention is credited to Hari C. Bajaj, Nettem V. Choudary, Mathew John, Checkalazhikathu R. Manoj, Bharat L. Newalkar, Dinesh Patil, Karikkethu P. Prasanth, Phani B. Rallapalli, Rajesh S. Somani, Rajendra S. Thakur.
Application Number | 20160339411 15/229566 |
Document ID | / |
Family ID | 46025800 |
Filed Date | 2016-11-24 |
United States Patent
Application |
20160339411 |
Kind Code |
A1 |
Bajaj; Hari C. ; et
al. |
November 24, 2016 |
ACTIVATED CARBON-METAL ORGANIC FRAMEWORK COMPOSITE MATERIALS WITH
ENHANCED GAS ADSORPTION CAPACITY AND PROCESS FOR THE PREPARATION
THEREOF
Abstract
The present invention discloses activated carbon-metal organic
framework composite materials (AC@MOF) with enhanced gas adsorption
capacity. The present invention also discloses a process for the
preparation of carbon-metal organic framework composite materials
(AC@MOF). The present invention involves the use of "void space
filling method" in metal organic frameworks (MOFs), which have been
accomplished by in-situ addition of selected type and appropriate
amount of activated carbon during the synthesis of MOF such as
Cu-BTC, in the storage of gases such as methane. The gas adsorption
capacity of these AC@MOF composite materials is significantly
increased through this method.
Inventors: |
Bajaj; Hari C.; (Bhavnagar,
IN) ; Somani; Rajesh S.; (Bhavnagar, IN) ;
Rallapalli; Phani B.; (Bhavnagar, IN) ; Patil;
Dinesh; (Bhavnagar, IN) ; Prasanth; Karikkethu
P.; (Bhavnagar, IN) ; Manoj; Checkalazhikathu R.;
(Bhavnagar, IN) ; Thakur; Rajendra S.; (Bhavnagar,
IN) ; John; Mathew; (Greater Noida, IN) ;
Newalkar; Bharat L.; (Greater Noida, IN) ; Choudary;
Nettem V.; (Greater Noida, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Council of Scientific & Industrial Research
Bharat Petroleum Corporation Limited |
New Delhi
Mumbai |
|
IN
IN |
|
|
Family ID: |
46025800 |
Appl. No.: |
15/229566 |
Filed: |
August 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14006729 |
Sep 23, 2013 |
9433919 |
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PCT/IB2012/000641 |
Mar 30, 2012 |
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15229566 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J 20/3064 20130101;
F17C 11/005 20130101; C07C 51/418 20130101; B01J 20/226 20130101;
Y02E 60/321 20130101; B01J 20/223 20130101; B01J 2220/40 20130101;
F17C 11/00 20130101; Y02C 10/08 20130101; Y02E 60/32 20130101; B01J
20/20 20130101; Y02C 20/40 20200801; C07C 51/418 20130101; C07C
63/307 20130101 |
International
Class: |
B01J 20/22 20060101
B01J020/22; B01J 20/20 20060101 B01J020/20 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2011 |
IN |
0919/DEL/2011 |
Claims
1-10. (canceled)
11. An activated carbon-metal organic framework composite materials
wherein the content of the activated carbon is from 1 wt % to 4 wt
% in the composite material.
12. The activated carbon-metal organic framework composite
materials as claimed in claim 11, wherein metal-organic frame work
is Cu-BTC.
13. The activated carbon-metal organic framework composite
materials as claimed in claim 11, wherein metal-organic frame work
is Cu.sub.3(BTC).sub.2.
14. The activated carbon-metal organic framework composite
materials as claimed in claim 11 are useful for storage of
gases.
15. The activated carbon-metal organic framework composite
materials as claimed in claim 14, wherein the gases is selected
from the group consisting of natural gas, methane, carbon dioxide
and hydrogen.
16. The activated carbon-metal organic framework composite
materials as claimed in claim 11, wherein enhancement of methane
adsorption capacity of activated carbon-metal organic framework
composite materials ranges between 20 wt % to 95 wt % as compared
to metal organic framework prepared without using activated carbon.
Description
FIELD OF INVENTION
[0001] The present invention relates to provide activated
carbon-metal organic framework composite materials (AC@MOF) with
enhanced gas adsorption capacity. More specifically, it relates to
a process for the preparation of metal organic frameworks (MOF) in
the presence of selected type and appropriate amount of activated
carbon to provide increased gas adsorption capacity for methane as
compared to MOF that have been synthesized without activated
carbon.
BACKGROUND OF THE INVENTION
[0002] Natural gas (NG) having methane as major component has
already been known as potential fuel for vehicular application.
Vehicles running on compressed natural gas (CNG) are on the roads.
However, there are pros and cons associated with use of CNG. The
alternate lies in the use of adsorbed natural gas (ANG).
Considering the potential of ANG, the Department of Energy (DoE) in
the United States has set targets as 180 v(STP)/v, at 3.5 MPa and
298 K [STP is standard temperature (298 K) and pressure (0.1 MPa)],
for methane storage in vehicular application. Research on
developing efficient materials and enhancing the capacity of known
materials such as porous silicates, carbons, and MOFs have been
pursued as means for methane storage. Although each of the prior
art work to some extent, more efficient storage materials are
necessary to cope with the DoE targets. The highest methane storage
capacity obtained in activated carbons is ca. 200 v/v [Wegrzyn, J.,
and Gurevich, M., "Adsorbent storage of natural gas", Appl. Energy,
55, 71-83 (1996)], although significant efforts were made on
processing activated carbons.
[0003] Metal organic-frameworks (MOFs) are a new class of
nanoporous materials that have potential applications in separation
processes, catalysis and gas storage. MOFs are synthesized using
organic linker molecules and metal clusters that self-assemble to
form materials with well defined pores, high surface areas, and
desired chemical functionalities. Because of these attractive
properties, MOFs are promising candidates for CO.sub.2 capture, as
well as methane and hydrogen storage.
[0004] A variety of MOFs have been screened for methane storage
[Wang, S., "Comparative molecular simulation study of methane
adsorption in metal-organic frameworks", Energy & Fuels, 21,
953-956 (2007); Noro, S., Kitagawa, S., Kondo, M., Seki, K., "A
new, methane adsorbent, porous coordination polymer [{CuSiF.sub.6
(4, 4'-bipyridine)2}n]", Angew. Chem. Int. Ed., 39, 2081-2084
(2000); Kondo, M., Shimamura, M., Noro, S. I., Minakoshi, S.,
Asami, A., Seki, K., Kitagawa, S., "Microporous materials
constructed from the interpenetrated coordination networks.
Structures and methane adsorption properties", Chem. Mater., 12,
1288-1299 (2000); Bourrelly, S., Llewellyn, Serre, C., Millange,
F., Loiseau, T., Ferey, G., "Different adsorption behaviors of
methane and carbon dioxide in the isotopic nanoporous metal
terephthalate MIL-53 and MIL-47", J. Am. Chem. Soc., 127,
13519-13521 (2005); Duren, T., Sarkisov, L., Yaghi, O. M., Snurr,
R. Q., "Design of new materials for methane storage", Langmuir, 20,
2683-2689 (2004); Ma, S., Sun, D., Simmons, J. M., Collier, C. D.,
Yuan, D., Zhou, H. C., "Metal-organic framework from an anthracene
derivative containing nanoscopic cages exhibiting high methane
uptake", J. Am. Chem. Soc., 130, 1012-1016 (2008).], but only a few
can reach the DoE target. For example, Duren et al. ["Duren, T.,
Sarkisov, L., Yaghi, O. M., Snurr, R. Q. Design of new materials
for methane storage", Langmuir, 20, 2683-2689 (2004)] proposed a
theoretical MOF (IRMOF-993) with a methane adsorption capacity of
181 v(STP)/v. Ma et al. [Ma, S., Sun, D., Simmons, J. M., Collier,
C. D., Yuan, D., Zhou, H. C., "Metal-organic framework from an
anthracene derivative containing nano-scopic cages exhibiting high
methane uptake", J. Am. Chem. Soc., 130, 1012-1016 (2008)]
synthesized a MOF named PCN-14 that gave the highest methane
adsorption capacity of 230 v(STP)/v so far. However, they used
crystal density rather than packed density in arriving at this
value.
[0005] Catenated MOFs are composed of two mutually catenated
frameworks that generate additional pores with various sizes. The
catenation structure strengthens the gas affinity for the material
by an entrapment mechanism that improves the gas adsorption
capacity and separation. Thus, catenation appeared to be a useful
strategy for designing new MOFs as efficient methane storage
materials. Based on this consideration, a systematic molecular
simulation study is performed to investigate the effect of
catenation on methane storage capacity to useful information for
further MOFs development with improved methane storage capacity.
[XUE Chunyu, ZHOU Zi'e, YANG Qingyuan and ZHONG Chongli, Enhanced
Methane Adsorption in Catenated Metal-organic Frameworks: A
Molecular Simulation Study, Chinese Journal of Chemical
Engineering, 17(4) 580-584 (2009)]. This work also showed that
catenated' MOFs can meet the DoE target easily for methane storage,
indicating that the creation of catenated frameworks is a promising
strategy for developing MOF-based efficient methane storage
materials in vehicular applications. However, it is still
theoretical study and no report published till date to prove such
strategy.
[0006] U.S. Pat. No. 7,196,210 (Omar M. Yaghi, et al., Mar. 27,
2007) describes isoreticular metal-organic frameworks, process for
forming the same and systematic design of pore size and
functionality therein, with application for gas storage. An
inventive strategy based on reticulating metal ions and organic
carboxylate links into extended networks has been advanced to a
point that has allowed the design of porous structures in which
pore size and functionality can be varied systematically. MOF-5, a
prototype of a new class of porous materials and one that is
constructed from octahedral Zn--O--C clusters and benzene links,
was used to demonstrate that its 3-D porous system can be
functionalized with the organic groups. Indeed, the data indicate
that members of this series represent the first mono crystalline
mesoporous organic/inorganic frameworks, and exhibit the highest
capacity for methane storage (155 cm.sup.3/cm.sup.3 at 36 atm.) and
the lowest densities (0.41 to 0.21 g/cm.sup.3) attained to date for
any crystalline material at room temperature. The drawback
associated with this material is its low densities which result in
less amount of material in a fixed volume. US 20100069234, (Richard
R. Willis, John J. Low, Syed A. Faheem, Annabelle I. Benin, Randall
Q. Snurr, and Ahmet Ozgur Yazaydin, describes the use of certain
metal organic frameworks that have been treated with water or
another metal titrant in the storage of carbon dioxide. The
capacity of these frameworks is significantly increased through
this treatment. The limitation of this invention is that the method
is shown suitable for storage of carbon dioxide and it does not
teach about methane storage.
[0007] In the present invention, it is shown that MOFs,
specifically Cu-BTC, can be easily tuned to significantly enhance
methane storage capacity simply by synthesizing the Cu-BTC in
presence of selected type and appropriate amount of activated
carbon there by filling the void space. This method for enhanced
storage of methane may apply to certain other guest molecules and
other MOFs also.
[0008] It is common practice to activate MOFs at about above
150.degree. C. to remove the solvent and open up the void space for
the adsorption of desired gas molecules. If the evacuation
temperature is high enough, all guest molecules entrapped during
the synthesis can be removed, including those that are
coordinatively bound to framework metal atoms. Removing these
coordinated solvent molecules leaves coordinatively-unsaturated,
open-metal sites that have been shown to promote gas uptake,
especially for H.sub.2 adsorption. Recently, Bae et al. [Youn-Sang
Bae, Omar K. Farha, Alexander M. Spokoyny, Chad A. Mirkin, Joseph
T. Hupp and Randall Q. Snurr, Chem. Commun., 2008, 4135-4131]
showed that in a carborane-based MOF removal of coordinated
dimethyl formamide increased CO.sub.2 and CH.sub.4 adsorption and
led to high selectivity for CO.sub.2 over methane. The open-metal
sites in MOFs are reminiscent of the extra-framework cations in
zeolites, in that they are expected to create large electric fields
and to readily bind polar molecules. Methane being non-polar
molecule is adsorbed in the overlapping force field created between
two walls of a pore.
[0009] Cu-BTC (also known as HKUST-1) is a well-studied MOF, first
synthesized by Chui et al. [S. S.-Y. Chui, S. M.-F. Lo, J. P. H.
Charmant, A. G. Orpen, I. D. Williams, Science 283 (1999)
1148-1150]. The structure of Cu-BTC is composed of large central
cavities (diameter 9.0 .ANG.) surrounded by small pockets (diameter
5.0 .ANG.), connected through triangular-shaped apertures of
similar size. The Cu-BTC framework has paddlewheel type metal
corners connected by benzene-1, 3, 5-tricarboxylate (BTC) linkers.
Each metal corner has two copper atoms bonded to the oxygen of four
BTC linkers. In the as-synthesized material, each copper atom is
also coordinated to one water molecule. MOFs have been found to
have the capacity to store methane readily and at high selectivity
over other gases such as nitrogen. In research publications,
several MOFs that have the capacity to store methane are described.
However, the storage capacity is not matching to the DoE targets,
and therefore, it is necessary to enhance the capacity for methane
storage to make them commercially useful.
[0010] In the present invention, a process has been developed and
described for enhancing the gas storage capacity of MOFs, and
especially for methane on Cu-BTC, by using "void space filling
method" that have been accomplished simply by in-situ addition of
selected type and appropriate amount of activated carbon, as `void
space filling agent`, during the synthesis of Cu-BTC, thereby
forming composite materials, AC@MOF. The gas storage capacity of
this AC@MOF composite material is significantly increased as
compared to the MOF synthesized without activated carbon.
OBJECTIVE OF PRESENT INVENTION
[0011] The main objective of present invention is to provide
activated carbon-metal organic framework composite materials
(AC@MOF) with enhanced gas adsorption capacity. Another objective
of the present invention is to provide a process for the
preparation of activated carbon-metal organic framework composite
materials (AC@MOF) with enhanced gas adsorption capacity.
SUMMARY OF THE INVENTION
[0012] Accordingly, the present invention provides activated
carbon-metal organic framework composite materials having general
formula [Cu.sub.3(BTC).sub.2.(H.sub.2O).sub.x.(AC).sub.y}.sub.n),
AC=activated carbon, with the elemental composition in the range C,
32 to 34 wt %; H, 1.90 to 2.20%; and M, 26 to 28% by wt.
[0013] In one embodiment of the present invention activated
carbon-metal organic framework composite materials are useful for
storage of gases.
[0014] In another embodiment of the present invention said gas is
selected from the Natural gas, methane, carbon dioxide and
hydrogen.
[0015] In another embodiment of the present invention enhancement
of methane adsorption capacity of activated carbon-metal organic
framework composite materials ranges between 20 wt % to 95 wt % as
compared to metal organic framework prepared without using
activated carbon.
[0016] In another embodiment of the present invention a process for
the preparation of activated carbon-metal organic framework
composite materials with enhanced gas adsorption capacity, wherein
the said process comprising the steps: [0017] a) dissolving an
organic ligand in an alcohol, preferably ethanol; [0018] b)
dissolving a metal salt in the water; [0019] c) mixing solution as
obtained in step (a) with solution as obtained in step (b) followed
by stirring at temperature ranging from 298K to 308K for a period
ranging between 10 to 50 min; [0020] d) transferring the reaction
mixture as obtained in step (c) into an autoclave and further
adding activated carbon in the range 1 to 3% in respect of weight
of product followed by heating at temperature ranging between 383K
and 423K for a period ranging between 15 to 20 hours to obtain
activated carbon-metal organic framework composite materials.
[0021] In another embodiment of the present invention mole ratio of
metal salt and organic ligand is in the range of 1.9 to 2.1.
[0022] In another embodiment of the present invention organic
ligand used in step (a) is Benzene di- and tri-carboxylic
acids.
[0023] In another embodiment of the present invention activated
carbon used in step (d) is selected from the group consisting of
charcoal, pet coke derived carbon, AP4-60 (Chemviron) and WS-480
(Chemviron).
[0024] In another embodiment of the present invention metal used in
step (b) is Copper.
[0025] In another embodiment of the present invention yield of
composite materials is in the range of 75 to 95%.
BRIEF DESCRIPTION OF THE DRAWING
[0026] FIG. 1 shows methane adsorption desorption isotherms at 303K
on `Cu-BTC-Bare` that has been synthesized without activated
carbon, and those of composite materials synthesized using 1, 2, 3
and 4 wt % activated carbon (AP4-60, Chemviron). Closed symbols
represent adsorption data and open symbols are desorption data.
[0027] FIG. 2 Shows methane adsorption-desorption isotherms at 303K
on 2% AC@Cu-BTC that has been synthesized in presence 2 wt % of
different types of activated carbons (AC). Closed symbols represent
adsorption data and open symbols are desorption data.
[0028] FIG. 3 Shows Powder XRD patterns of as synthesized Cu-BTC
and 2% AP-460@Cu-BTC
[0029] FIG. 4 Shows Transmission Electron Microscopy images of 2%
AP-460@Cu-BTC.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Reference will now be made in detail to presently preferred
embodiments and methods of the invention, which constitute the best
modes of practicing the invention presently known to the
inventors.
[0031] As used herein "guest" means any chemical species that
resides within the void regions of an open framework solid (such as
MOF) that is not considered integral to the framework. Such as
molecules of the solvent (water or Dimethyl formamide) that fill
the void regions during the synthetic process of MOF, other
molecules that are replaced for the solvent molecules after
evacuation are gases in a sorption experiment.
[0032] As used herein "void space filling agent" means a guest
species that fills the void regions of an open framework during
synthesis. Materials that exhibit permanent porosity remain intact
even after removal of the guest species such as solvent molecules
or molecular charge-balancing species via heating and/or
evacuation. Sometimes, void space filling agents are referred to as
templating agents.
[0033] As used herein "void space filling method" means a method by
which a void space filling agent is incorporated in the porous
structure usually by adding in-situ during synthesis. It can be
also referred to as the method by which the under-utilized or
un-used void space within the MOF is reduced by incorporation of
void space filling agent thereby creating more micro porosity which
contributes significantly to enhance the methane storage
capacity.
[0034] MOFs are highly porous materials that can store gas
molecules such as CO.sub.2 and methane, readily and at high
selectivity over other gases such as nitrogen. Typically the
adsorption is simple physisorption. MOFs possess large pore volume
which is in most of the cases remained under utilized after
adsorption of gas such as methane. In the present invention it has
been found that if the un-utilized void of the MOFs is reduced
simply by use of void space filling method which is accomplished by
incorporating certain type and amount of activated carbon as void
space filling agent during the synthesis of MOFs, significantly
increases the MOF's capacity for methane storage. In particular, a
MOF known as Cu-BTC has been made to adsorb more methane than that
synthesized without activated carbon.
[0035] Several MOFs have open metal sites (coordinatively
unsaturated) that are built into the pore "walls" in a repeating,
regular fashion. These metal sites, such as those found in Cu-BTC
or MIL-101, have been shown to impart catalytic activity to the
materials. The partial positive charges on the metal sites in MOFs
also have the potential to enhance general adsorption properties.
This has often been discussed as a strategy for increasing hydrogen
adsorption in MOFs.
[0036] The MOFs that are useful in the present invention have large
surface area, large void space/pore volume, and accessible metal
sites. The major portion of void space remain under-utilized after
activation i.e. removing solvent molecules or molecular charge
balancing species by heating and/or evacuation, followed by gas
adsorption, among such MOFs are Cu-BTC, (or HKUST-1), MOF-5, MIL-53
and MIL-101, etc. The preparation of these MOFs is described in the
scientific literature.
[0037] Cu-BTC, one of the most extensively studied MOF, both
experimentally and theoretically, has a face-centered cubic crystal
structure and contains an intersecting 3D system of large
square-shaped pores (9.times.9 .ANG.) composed of paddle-wheel
units assembled from two copper atoms and four benzene
tri-carboxylate (BTC) groups. The structure of Cu-BTC has two kinds
of domains: (1) tetrahedron side pockets (.about.5 .ANG. diameter
with 3.5 .ANG. windows) and large square-shaped channels. The unit
cell has a free volume of 66% and a BET surface area ranging from
1200 to over 2000 m.sup.2/g.
Materials Synthesis and Characterization
[0038] Cu-BTC can be synthesized by several methods [(a) 0. M.
Yaghi, G. M. Li, and H. L. Li, Nature 378 (1995) 703-706; (b) S.
S.-Y. Chui, S. M. F. Lo, J. P. H. Charmant, A. G. Orpen, I. D.
Williams, Science 283 (1999) 1148-1150]. However, in the present
invention Cu-BTC is synthesized as per the method reported by Qing
Min Wang, et al.
[0039] [Qing Min Wang, Dongmin Shen, Martin Bulow, Miu Ling Lau,
Shuguang Deng, Frank R. Fitch, Norberto O. Lemcoff, Jessica
Semanscin, Microporous and Mesoporous Materials 55 (2002) 217-230].
Furthermore, four different samples are prepared by adding varying
amount of commercially available activated carbon (such as AP4-60,
Chemviron) after grinding and passing through 60 BSS mesh during
the synthesis of Cu-BTC. The first sample (1% AP-460@CuBTC) was
prepared by loading 1 wt % of activated carbon (AP4-60) in-situ
during the synthesis of Cu-BTC, the second one (2% AP-460@CuBTC)
was prepared by loading 2 wt % of the same carbon, and the third
one (3% AP-460@CuBTC) with a 3 wt % loading of AP4-60.
[0040] Likewise, (4% AP-460@CuBTC) was prepared by 4 wt % AP4-60
loading. Over and above this, four different AC@CuBTC composite
materials are prepared by adding 2 wt % each of AP4-60, WS-480, Pet
coke derived activated carbon and Charcoal, during the synthesis of
Cu-BTC. The experimental isotherms for methane adsorption were
measured at 303K up to 4000 kPa (i.e. 40 bars) after activation of
sample at 423K with continuous evacuation for overnight period
using BELSORP-HP Inc., Japan). Over the pressure range examined,
except the sample 1% AP-460@CuBTC, all other samples adsorb more
methane than the `CuBTC-Bare` sample (FIG. 1). In fact, the
isotherms for `CuBTC-bare` and 1% AP-460@CuBTC are overlapping
indicating no enhancement in methane adsorption capacity. The 2%
AP-460@CuBTC adsorbs maximum methane than all the other samples
(see Table 1). It is noted that 3% AP-460@CuBTC has better
adsorption capacity than 4% AP-460@CuBTC. However, both these
samples have lower adsorption capacity for methane than that of 2%
AP-460@CuBTC. It is inferred from FIG. 1 that loading of 2% AP-460
during synthesis resulted in 2% AP-460@CuBTC composite material
which has highest methane capacity of 190.3 cc/g. Therefore, it can
be used to enhance the affinity of the material for methane without
affecting the desorption which is completely reversible.
[0041] Powder X-ray diffraction (PXRD) patterns of MOF and AC@MOF
materials were recorded with a Philips X'Pert diffractometer using
nickel-filtered, Cu K.sub..alpha. radiation (.lamda.=1.5418 .ANG.)
over a range of 5 degree <2.theta.<60 degrees. The PXRD
patterns of the as-synthesized material "CuBTC-Bare" and that of 2%
AP-460@CuBTC are almost similar indicating that upon loading of the
activated carbon in Cu-BTC the structure is not collapsed. However,
some of the peaks are differed in intensities indicating slight
distortion of the structure due to incorporation of amorphous
activated carbon (FIG. 3).
[0042] The Transmission electron microscopy image of 2%
AP-460@Cu-BTC is shown in FIG. 4. It clearly shows the lattice
structure of Cu-BTC and the presence of activated carbon.
[0043] The experimental isotherms for methane adsorption measured
at 303K up to 4000 kPa (i.e. 40 bars) after activation of samples
at 423K with continuous evacuation for overnight period using
BELSORP-HP (Bell Inc., Japan) revealed that addition of 2 wt %
AP4-60 only show enhancement of methane sorption capacity (FIG. 2).
In contrast, use of other carbons reduce the methane capacity in
the order of 2% WS-480@CuBTC>CuBTC-Bare>2% Pet coke derive
carbon@CuBTC>2% Charcoal@CuBTC. It is clear from FIG. 2 that
loading of 2 wt % of AP4-60 and WS-480 (Chemviron) are only
enhancing the methane capacity of Cu-BTC but other carbons do not
show this behavior.
[0044] The extrudes prepared using 2% AP-460@Cu-BTC prepared on 400
g/batch scale and 5 wt % CMC sodium salt as binder showed methane
adsorption capacity of 142 cm.sup.3/g (Table 2). The packing
density of this material is about 1.0 g/cc. Thus, the methane
adsorption capacity of extrudes is 142 cm.sup.3/cm.sup.3. Such
composite material may be useful in vehicular applications. To
further illustrate the inventive AC@MOF composite materials and
methods for making them, the following examples are given. It is to
be understood that these examples are provided for illustrative
purposes and are not to be construed as limiting the scope of the
present invention.
EXAMPLES
Example 1
Preparation of "CuBTC-Bare"
[0045] Cu-BTC is synthesized by an improved process reported by
Qing Min Wang, et al. [Qing Min Wang, Dongmin Shen, Martin Bulow,
Miu Ling Lau, Shuguang Deng, Frank R. Fitch, Norberto O. Lemcoff,
Jessica Semanscin, Microporous and Mesoporous Materials 55 (2002)
217-230]. The recipe is as follows.
[0046] Benzene-1, 3, 5-tricarboxylic acid (49.1 g, 0.234 mol) was
dissolved into ethanol (250 ml), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 108.6 g, 0.466 mol) was dissolved
into water (250 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. The autoclave was heated at temperature, 393K, under
hydrothermal conditions for 18 h. The reaction vessel was cooled to
ambient temperature (300K), and blue crystals of Cu-BTC were
isolated by filtration, and washed with water. The product was
dried at 383 K, overnight. The yield was quantitative (90 g). The
compound has been formulated as
[Cu.sub.3(BTC).sub.2-(H.sub.2O).sub.x].sub.n, by elemental analysis
and X-ray diffraction studies [Qing Min Wang, Dongmin Shen, Martin
Bulow, Miu Ling Lau, Shuguang Deng, Frank R. Fitch, Norberto O.
Lemcoff, Jessica Semanscin, Microporous and Mesoporous Materials 55
(2002) 217-230]. The as-synthesized Cu-BTC was designated as
`CuBTC-Bare`. The methane adsorption capacity of this sample is
100.4 cm.sup.3/g (Table 1).
Example 2
Preparation of 1% AP-460@CuBTC
[0047] Benzene-1, 3, 5-tricarboxylic acid (24.55 g, 0.117 mol) was
dissolved into ethanol (125 nil), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 54.3 g, 0.233 mol) was dissolved
into water (125 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Commercially available activated carbon AP4-60
(Chemviron) (0.375 g) was added in to the reaction mixture and
mixed properly. The autoclave was heated at temperature, 393 K
under hydrothermal conditions for 18 h. The reaction vessel was
cooled to ambient temperature (300K), and blackish blue crystals
were isolated by filtration, and washed with water. The product was
dried at 383 K, overnight. The yield was quantitative (48 g). The
product was designated as "1% AP-460@CuBTC". The methane adsorption
capacity of this sample is 100.8 cm.sup.3/g (Table 1).
Example 3
Preparation of 2% AP-460@CuBTC
[0048] Benzene-1, 3, 5-tricarboxylic acid (24.55 g, 0.117 mol) was
dissolved into ethanol (125 ml), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 54.3 g, 0.233 mol) was dissolved
into water (125 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Commercially available activated carbon AP4-60
(Chemviron) (0.75 g) was added in to the reaction mixture and mixed
properly. The autoclave was heated at temperature, 393 K under
hydrothermal conditions for 18 h. The reaction vessel was cooled to
ambient temperature (300K), and blackish blue crystals were
isolated by filtration, and washed with water. The product was
dried at 383 K, overnight. The yield was quantitative (50 g). The
product was designated as "2% AP-460@CuBTC". The methane adsorption
capacity of this sample is 190.3 cm.sup.3/g (Table 1).
Example-4
Preparation of 3% AP-460@CuBTC
[0049] Benzene-1, 3, 5-tricarboxylic acid (24.55 g, 0.117 mol) was
dissolved into ethanol (125 ml), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 54.3 g, 0.233 mol) was dissolved
into water (125 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Commercially available activated carbon AP4-60
(Chemviron) (1.125 g) was added in to the reaction mixture and
mixed properly. The autoclave was heated at temperature, 393 K
under hydrothermal conditions for 18 h. The reaction vessel was
cooled to ambient temperature (300K), and blackish blue crystals
were isolated by filtration, and washed with water. The product was
dried at 383 K, overnight. The yield was quantitative (45 g). The
product was designated as "3% AP-460@CuBTC". The methane adsorption
capacity of this sample is 129.8 cm.sup.3/g (Table 1).
Example-5
Preparation of 4% AP-460@CuBTC
[0050] Benzene-1, 3, 5-tricarboxylic acid (24.55 g, 0.117 mol) was
dissolved into ethanol (125 ml), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 54.3 g, 0.233 mol) was dissolved
into water (125 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Commercially available activated carbon AP4-60
(Chemviron) (1.5 g) was added in to the reaction mixture and mixed
properly. The autoclave was heated at temperature, 393 K under
hydrothermal conditions for 18 h. The reaction vessel was cooled to
ambient temperature (300K), and blackish blue crystals were
isolated by filtration, and washed with water. The product was
dried at 383 K, overnight. The yield was quantitative (45 g). The
product was designated as "4% AP-460@CuBTC. The methane adsorption
capacity of this sample is 120.0 m.sup.3/g (Table 1).
Example-6
Preparation of 2% WS-480@CuBTC
[0051] Benzene-1, 3, 5-tricarboxylic acid (24.55 g, 0.117 mol) was
dissolved into ethanol (125 ml), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 54.3 g, 0.233 mol) was dissolved
into water (125 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Commercially available activated carbon WS-480
(Chemviron) (0.75 g) was added in to the reaction mixture and mixed
properly. The autoclave was heated at temperature, 393 K, under
hydrothermal conditions for 18 h. The reaction vessel was cooled to
ambient temperature (300K), and blackish blue crystals were
isolated by filtration, and washed with water. The product was
dried at 383 K, overnight. The yield was quantitative (45 g). The
product was designated as "2% WS-480@CuBTC". The methane adsorption
capacity of this sample is 150.7 cm.sup.3/g (Table 2).
Example-7
Preparation of 2% Petcoke derived AC@CuBTC
[0052] Benzene-1, 3, 5-tricarboxylic acid (24.55 g, 0.117 mol) was
dissolved into ethanol (125 nil), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 54.3 g, 0.233 mol) was dissolved
into water (125 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Pet coke derived AC (prepared in our laboratory by
chemical activation of pet coke with KOH) (0.75 g) was added in to
the reaction mixture and mixed properly. The autoclave was heated
at temperature, 393 K under hydrothermal conditions for 18 h. The
reaction vessel was cooled to ambient temperature (300K), and
blackish blue crystals were isolated by filtration, and washed with
water. The product was dried at 383 K, overnight. The yield was
quantitative (42 g). The product was designated as "2% Pet coke
derived AC@CuBTC". The methane adsorption capacity of this sample
is 59.8 cm.sup.3/g (Table 2).
Example-8
Preparation of 2% Charcoal@CuBTC
[0053] Benzene-1, 3, 5-tricarboxylic acid (24.55 g, 0.117 mol) was
dissolved into ethanol (125 ml), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 54.3 g, 0.233 mol) was dissolved
into water (125 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Commercially available Charcoal (0.75 g) was added in
to the reaction mixture and mixed properly. The autoclave was
heated at temperature, 393 K, under hydrothermal conditions for 18
h. The reaction vessel was cooled to ambient temperature (300K),
and blackish blue crystals of Cu-BTC were isolated by filtration,
and washed with water. The product was dried at 383 K, overnight.
The yield was quantitative (40 g). The product was designated as
"2% Charcoal@CuBTC. The methane adsorption capacity of this sample
is 41.3 cm.sup.3/g (Table 2).
Example-9
Preparation of 2% AP-460@CuBTC (Scale up)
[0054] Benzene-1, 3, 5-tricarboxylic acid (245.5 g, 1.17 mol) was
dissolved into ethanol (1250 ml), and cupric nitrate hydrate
(Cu(NO.sub.3).sub.2.3.0H.sub.2O; 543 g, 2.33 mol) was dissolved
into water (1250 ml). The two solutions were mixed at ambient
temperature (300K) for 30 min, and the mixture was transferred into
an autoclave. Commercially available activated carbon AP4-60
(Chemviron) (7.5 g) was added in to the reaction mixture and mixed.
The autoclave was heated at temperature, 393 K, under hydrothermal
conditions for 18 h. The reaction vessel was cooled to ambient
temperature (300K), and blackish blue crystals were isolated by
filtration, and washed with water. The product was dried at 383 K,
overnight. The yield was quantitative (450 g). The product was
designated as "2% AP-460@CuBTC (Scale up). The methane adsorption
capacity of this sample is 156.9 cm.sup.3/g (Table 2).
Example-10
Preparation of Extrudes of 2% AP-460@CuBTC (Scale up)
[0055] The product "2% AP-460@CuBTC (Scale up)" (400 g) is mixed
with 20 g of carboxy methyl cellulose sodium salt (CMC-sodium salt)
and sufficient quantity of deionized water is added to form dough
like extrudable mass. It was kneaded properly to form uniform dough
like mass. The mass is then extruded using a kitchen machine.
Alternately, a single screw type Micro extruder fitted with axial
discharge system can also be used for the purpose. The extrudate
(2-3 mm diameter) thus prepared is dried first at room temperature
and then at 383K for overnight period. It was broken in small
pieces manually to obtain extrudes with the length in the range 4-6
mm. The methane adsorption capacity of this extrudes is 142.0
cm.sup.3/g (Table 3). The packing density of this extrudes is
determined to be .about.1.0 g/cc. Thus, the extrudate is having
142.0 cm.sup.3/g methane adsorption capacity (Table 2).
TABLE-US-00001 TABLE 1 Methane adsorption capacity of CuBTC-Bare
and those of AP-460@CuBTC with different amount of AP4-60 Methane
adsorption capacity Sample at 3500 kPa, 303K CuBTC-Bare 100.4 1%
AP460@Cu-BTC 100.8 2% AP460@Cu-BTC 190.3 3% AP460@Cu-BTC 129.8 4%
AP460@Cu-BTC 120.0 AP4-60 118.0
TABLE-US-00002 TABLE 2 Methane adsorption capacity of AC@CuBTC with
different types of activated carbons Methane adsorption capacity
Sample at 3500 kPa, 303K CuBTC-Bare 100.4 2% AP-460@Cu-BTC 190.3 2%
WS-480@Cu-BTC 150.7 2% Pet coke carbon@Cu-BTC 59.8 2%
Charcoal@Cu-BTC 41.3 2% AP-460@Cu-BTC (Scale up) 156.9 Extrudes of
2% AP-460@Cu-BTC(scale up), 142.0 Prepared using 5% CMC-sodium
salt
Advantages of Present Invention
[0056] In the present invention, we disclosed the successful
enhancement of gas adsorption capacity, by synthesizing activated
carbon--metal organic framework composite material, such as
AC@CuBTC. The process of preparing the composite material is simple
and easy to perform as it involve only one more step i.e. addition
of selected type and appropriate amount of activated carbon,
readily available in the market, in-situ during the conventional
synthesis of metal organic frame work material. This process
eliminates the post synthesis treatment required for the
enhancement of gas adsorption capacity as reported by other
researchers. The under-utilized pore or void space volume have been
filled with activated carbon so that the affinity for methane is
increased without changing the original structure of MOF. The
quantity of activated carbon required to enhance the methane
adsorption capacity is very small and therefore do not contribute
much in cost of production. This will be very advantageous for
commercial production of such methane storage material for
vehicular applications. Furthermore, the implications and scope of
such synthesis process are revealed by the methane sorption
properties of several activated carbon-MOF composite materials,
where, the highest methane storage capacity obtained for composite
powder is 190.3 cm.sup.3/g which is very close to that of carbon
(200 cm.sup.3/g) reported in the literature, and the packing
density of material has been determined to be about 1.0 g/cm.sup.3.
Thus, its V/V capacity would be the same as cm.sup.3/g which is
most desirable to provide a material having advantageously enhanced
methane adsorption capacity. Yet further advantage is that the
process can be scaled up to produce composite material. It is also
possible to form shaped body such as extrude of AC@MOF using binder
such as CMC-sodium salt which is also available commercially and
the amount of binder used is merely 5 wt %. Still further, it would
be advantageous to provide such a composite material which can
advantageously store gases at desirable pressures such as the
predominant natural gas methane.
* * * * *