Low Pressure Storage of Methane on Interlayered Clays for Potential Vehicular Applications

摘要

Inexpensive, high surface area sorbents were prepared by treating naturally occurring hectorite and bentonite clays with aluminum chlorohydroxide, zirconium chlorohydroxide, or silica-sol solutions. Data were obtained comparing these interlayered clays with activated carbons and zeolites as sorbents for the low pressure storage of methane onboard natural gas powered vehicles. Methane sorption at pressures up to 7 MPa (1000 psig) resembled a Langmuir-type curve with a saturation sorption equal to about six micromoles of methane per square meter of surface area. Even at low pressures, methane sorption capacity was largely determined by surface area. At 2.2 MPa (300 psig), the best interlayered clay sorbed less than one-third the methane sorbed by an equal volume of Witco grade 9JXC activated carbon. Both the activated carbons and interlayered clays exhibited excellent release-on-demand capability. Driving ranges were calculated for a 2500-lb automobile equipped with three, 35-liter fuel tanks filled with sorbent and pressurized to 3.6 MPa (500 psig) with methane. Enough methane was stored with the best interlayered clay to travel 41 km (25 mi). With 9JXC carbon, one could travel 82 km (51 mi). The same vehicle equipped with high pressure (2400 psig) fuel tanks having the same volume but containing no sorbent would have a 190 km (118 mi) range. (ERA citation 10:016515)