Presentation on theme: "Methane Storage: Gas storage is determined gravimetrically. Methane storage is primarily determined at 500 psig (3.5 MPa) and 293.15 K, for application."— Presentation transcript:
Methane Storage: Gas storage is determined gravimetrically. Methane storage is primarily determined at 500 psig (3.5 MPa) and K, for application to alternative MPa) and 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 grams of methane per kilogram of carbon, non-briquetted sample,S-33/k, stores g/kg. Hydrogen Storage: Hydrogen storage is determined at 700 psig (4.9 MPa) at both K and 77.3 K. Hydrogen isotherms were also run by Hiden Ltd. S-33/k has a mass for mass value of g/kg at 77.3 K and 10 g/kg at K. 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 part of the ALL-CRAFT Internship Program Introduction: Networks of fractal nanopores in activated carbon have recently been discovered (Pfeifer et al., Phys. Rev. Lett. 88, (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. 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. 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 m 2 /g and recent samples have shown surface areas as large as 3668 m 2 /g. Acknowledgements: This research is based on work supported by the National Science Foundation, under grant No. EEC , and the University of Missouri. 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. CH 4 ALL-CRAFT Best Performance S-33/k ANG DOE Target M/V g/L 118 g/L V/V L/L 180 L/L H2H2H2H2 77 K 298 K H DOE Target M/V g/L 5 g/L 45 g/L M/M g/kg 10 g/kg 64 g/kg Fig. 1: Missouri corn cob starting material and finished briquette. Fig. 2: SEM images of sample B-18 showing pore openings (arrows). SEM done at the University of Missouri Microscopy Core. Fig. 5: Gravimetric sample cell and methane adsorption set-up. 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. 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. Fig. 3: Nitrogen adsorption isotherm on S-33/k showing lack of adsorption-desorption hysteresis. Fig. 4: NLDFT differential pore volume distribution done assuming slit-cylindrical shaped pores.