Gas Storage Capabilities and Structure of Nanoporous Carbon Jacob Burress, Mikael Wood, *Sarah Barker, *Carol Faulhaber, Demetrius Taylor, Peter Pfeifer Physics Department, University of Missouri-Columbia *Work done at University of Missouri-Columbia as

1
Gas Storage Capabilities and Structure of
Nanoporous CarbonJacob Burress, Mikael Wood,
Sarah Barker, Carol Faulhaber, Demetrius
Taylor, Peter PfeiferPhysics Department,
University of Missouri-ColumbiaWork done at
University of Missouri-Columbia as part of the
ALL-CRAFT Internship Program
Methane Storage Gas storage is determined
gravimetrically. Methane storage is primarily
determined at 500 psig (3.5 MPa) and 293.15 K,
for application to alternative fuel technology.
Methane adsorption isotherms, figure 6, are
used to determine deliverable pressure as well
as to determine to pore size Distribution, PSD,
figure 7. Current typical briquetted samples
store 148-227 grams of methane per kilogram of
carbon, non-briquetted sample,S-33/k, stores
230-239 g/kg. Hydrogen Storage Hydrogen
storage is determined at 700 psig (4.9 MPa) at
both 293.15 K and 77.3 K. Hydrogen isotherms
were also run by Hiden Ltd. S-33/k has a mass
for mass value of 71-90 g/kg at 77.3 K and 10
g/kg at 293.15 K.

• Introduction
• Networks of fractal nanopores in activated carbon
  have
• recently been discovered (Pfeifer et al., Phys.
  Rev. Lett. 88,
• 115502 (2002)). These networks have shown
  promise in
• the storage of methane and hydrogen for use as
  alternative
• fuels. Our group produces activated carbon made
  from
• Missouri corn cob, figure 1. Analysis of the
  pore structure
• of these carbons is required in order to optimize
  the storage
• capabilities. A pore width of 1.1 nanometers is
  ideal for
• methane storage. Other properties, such as
  surface area,
• are also studied for use in the development of
  larger
• storage capacities.

Fig. 5 Gravimetric sample cell and methane
adsorption set-up.
Fig. 1 Missouri corn cob starting material and
finished briquette.
Scanning Electron Microscopy Scanning electron
microscopy (SEM) is used to qualitatively
support the other methods of pore size
predictions. One can see the entrances to the
pore networks in figure 2.
Fig. 6 Methane adsorption isotherm on S-33/k.
Assuming a minimum pressure of 0.27 MPa gives a
deliverable amount of methane of 160 g/kg.
Conclusions Analysis of the properties of
carbon has lead to increased storage capacity.
Further analysis needs to be to help optimize
the carbons for both hydrogen and methane
storage.
Fig. 2 SEM images of sample B-18 showing pore
openings (arrows). SEM done at the University of
Missouri Microscopy Core.
Nitrogen Adsorption Isotherms The use of
nitrogen adsorption isotherms is a popular
method for pore analysis of solids. We use a
Quantachrome Autosorb 1-C to attain these
isotherms. Figure 3 shows the isotherm for
S-33/k, our current best performer for both
hydrogen and methane storage. The lack of
hysteresis between the adsorption-desorption
values is desirable for storage and delivery of
gases. The differential pore volume
distribution was done using the slit/cylinder
non-local density functional theory kernel
provided in the Autosorb Software, figure 4. A
large predominance of nanopores is shown. The
BET surface area of S-33/k is 2553 m2/g and
recent samples have shown surface areas as large
as 3668 m2/g.
Fig. 7 PSD determined from methane isotherm.
This a predominance of nanopores with width
around 1.5 nm.
Fig. 8 Hydrogen storage isotherm performed on
S-33/k by Hiden Ltd on IGA-001 instrument.
CH4 ALL-CRAFT Best Performance S-33/k ANG DOE Target
M/V 115-119 g/L 118 g/L
V/V 176-182 L/L 180 L/L
Fig. 3 Nitrogen adsorption isotherm on S-33/k
showing lack of adsorption-desorption hysteresis.
Acknowledgements This research is based on work
supported by the National Science Foundation,
under grant No. EEC-0438469, and the University
of Missouri.
H2 77 K 298 K H2 2010 DOE Target
M/V 34-46 g/L 5 g/L 45 g/L
M/M 71-90 g/kg 10 g/kg 64 g/kg
Fig. 4 NLDFT differential pore volume
distribution done assuming slit-cylindrical
shaped pores.