Hydrogen production by water dissociation using mixed conducting dense ceramic membranes

Hydrogen separation membranes - annual report for FY 2007.

“…The hydrogen production rate increased with increasing pH 2 on the oxygen-permeate side, as expected, but it deviated from a logarithmic dependence on pH 2 . By contrast, a logarithmic dependence was obtained in our study with ANL-1b membranes [13] when we minimized the limitations from surface reaction kinetics by adding porous layers to the membrane. The deviation from a logarithmic dependence (Fig.…”

“…Hydrogen and helium concentrations in the sweep gas are measured by briefly (≈45 s) diverting the sweep gas from building exhaust to a gas chromatograph (GC). (4) and high-pressure HR-160 tubes (2) are placed inside protection tube (3), which is inside a cylindrical heating element (19), all of which is contained in a secondary containment tube (13). The protection tube protects the heating element from gas that would flow at high velocity in the event of a leak from the sample, seals, or HR-160 tubes; it also protects the heating element when the sample and tubes are loaded into the reactor.…”

“…Mass flow controllers (35) control the flow rates of feed and sweep gases into the reactor, while mass flow meters (33) measure the flow rates of feed and sweep gases out of the reactor. A purge gas composed of 100 ppm H 2 /balance N 2 flows through the secondary containment tube (13) to carry leakage from the reactor to the building exhaust. Sensors (15), (16), and (17) monitor the purge gas as it exits the reactor, and a pneumatic valve stops the flow of feed and sweep gases if any of the following alarm conditions occurs: Fig.…”

“…i) Hydrogen Production Using SFC2 as OTM The ANL-0b OTM is composed of SFC2 and yields a hydrogen production rate at 900°C that is ≈2 times higher than that of the ANL-1b OTM [12]. Our previous study of the ANL-0b membrane showed that its hydrogen production rate at 900°C might be limited by the surface oxygen exchange kinetics [13]. To clarify whether the hydrogen production rate of ANL-0b is limited by bulk or surface kinetics, we measured the hydrogen production rate as a function of membrane thickness (0.21-0.98 mm).…”

A novel porous‐dense dual‐layer composite membrane reactor with long‐term stability

“…[1][2][3] Dense mixed ion-electronic conducting (MIEC) materials, with great oxygen ionic and electronic conductivities at high temperatures have attracted considerable interests in many applications such as effective utilization of natural gas [4][5][6][7][8][9][10][11][12][13] or coke oven gas, 14,15 production of hydrogen, [16][17][18] selective oxidation of light hydrocarbons to high-added-value-chemicals [19][20][21][22] , and treatment of atmospheric pollutants, expecially CO 2 and NO X . 11,[23][24][25] MIEC membrane reactors can overcome many of the shortcomings of conventional packed-bed reactors.…”