TY - JOUR
T1 - A 1H NMR pulse gradient spin-echo (PGSE) study of the mass transport of dimethyl oxalate and ethylene glycol
T2 - New fuels for the DOFC
AU - Suarez, S.
AU - Chung, S. H.
AU - Greenbaum, S.
AU - Bajue, S.
AU - Peled, E.
AU - Duvdevani, T.
N1 - Funding Information:
This research was supported in part by the US Office of Naval Research, the US Air Force of Scientific Research, and the Israel Science Foundation. S.S. also received support from MBRS program, funded by the US National Institute of Health and the LSAMP program, funded by the US National Science Foundation. We would like to thank Dr. Phillip Stallworth and Mr. Michele Vittadello for their insightful discussions.
PY - 2003/6/30
Y1 - 2003/6/30
N2 - Direct oxidation fuel cell (DOFC) based on proton conducting membranes (PCM's) represents a promising energy technology, with the vast majority of efforts devoted to methanol as the fuel. The most commonly used PCM is Nafion. However, because of high production cost, high fuel crossover, and sensitivity to metal-ion impurities, alternative materials are being developed. Methanol presents several limitations including low boiling point (∼65 °C), and reduced cell efficiency due to fuel crossover. We present here a measure of the mass transport represented by the self-diffusion coefficients (D) of methanol, and two alternative fuels - ethylene glycol (EG) and dimethyl oxalate (DMO) in new low-cost nanoporous (NP) PCM's. The NP-PCM's are based on commercial poly(vinylidene fluoride), with variable pore size determined by the addition of nanoscale SiO2 or TiO2 particles. Proton NMR pulsed gradient spin-echo (PGSE) self-diffusion measurements were conducted on aqueous solutions of 2 M fuel in 3 M H2SO4 and also on five NP-PCM equilibrated in the aqueous solutions over the temperature range of 30-90 °C. Here the fuel molecular mobility is indicated by the D values of the methyl and methylene peaks. Results indicate that both DMO and EG solutions have lower fuel molecular mobility than methanol. Results for the various NP-PCM also reveal reduced fuel permeability for DMO and EG compared with methanol.
AB - Direct oxidation fuel cell (DOFC) based on proton conducting membranes (PCM's) represents a promising energy technology, with the vast majority of efforts devoted to methanol as the fuel. The most commonly used PCM is Nafion. However, because of high production cost, high fuel crossover, and sensitivity to metal-ion impurities, alternative materials are being developed. Methanol presents several limitations including low boiling point (∼65 °C), and reduced cell efficiency due to fuel crossover. We present here a measure of the mass transport represented by the self-diffusion coefficients (D) of methanol, and two alternative fuels - ethylene glycol (EG) and dimethyl oxalate (DMO) in new low-cost nanoporous (NP) PCM's. The NP-PCM's are based on commercial poly(vinylidene fluoride), with variable pore size determined by the addition of nanoscale SiO2 or TiO2 particles. Proton NMR pulsed gradient spin-echo (PGSE) self-diffusion measurements were conducted on aqueous solutions of 2 M fuel in 3 M H2SO4 and also on five NP-PCM equilibrated in the aqueous solutions over the temperature range of 30-90 °C. Here the fuel molecular mobility is indicated by the D values of the methyl and methylene peaks. Results indicate that both DMO and EG solutions have lower fuel molecular mobility than methanol. Results for the various NP-PCM also reveal reduced fuel permeability for DMO and EG compared with methanol.
KW - Alternative fuels
KW - Electrochemical devices
KW - Fuel cells
KW - Nano-porous proton conduction membranes (NP-PCM's)
KW - Pulsed field-gradient NMR
KW - Self-diffusion coefficient
UR - http://www.scopus.com/inward/record.url?scp=0038377697&partnerID=8YFLogxK
U2 - 10.1016/S0013-4686(03)00203-2
DO - 10.1016/S0013-4686(03)00203-2
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AN - SCOPUS:0038377697
VL - 48
SP - 2187
EP - 2193
JO - Electrochimica Acta
JF - Electrochimica Acta
SN - 0013-4686
IS - 14-16 SPEC.
ER -