Device for sampling and enriching impurities in hydrogen comprising hydrogen-permeable membrane
Provided herein are methods and devices to enrich trace quantities of impurities in gaseous mixtures, such as hydrogen fuel. The methods and devices rely on concentration of impurities so as to allow the detection of the impurities using commonly-available detection methods.
1. A device for increasing the concentration of impurities in a batch of hydrogen gas, the device comprising:
a first container having an interior void having a first volume V 1 adapted to receive the batch at a first pressure P hi , wherein the batch contains hydrogen gas and an unknown quantity of trace impurities;
a second container downstream and in fluid communication with the first container, wherein the second container has an interior void having a second volume V 2 and, wherein the void of the second container is in fluid communication with a hydrogen-permeable membrane that allows passage of hydrogen gas into a first conduit, said membrane impermeable to the impurities, wherein the interior void of the second container is not in physical communication with the first conduit, wherein hydrogen gas and impurities are retained in the interior void of the second container at a second pressure P Lo lower than the first pressure;
a second conduit in fluid communication with and downstream from the second container; and
an analytical device downstream from and in fluid communication with the second conduit wherein the analytical device, and wherein the system comprising the first and second containers is a reversibly closeable system wherein no further gas is permitted into the system during treatment of an aliquot wherein impurities retained in the interior void of the second chamber are concentrated by a factor of
P
h
i
V
1
P
l
o
V
2
with respect to the concentration of the impurities of the batch of hydrogen gas.
2. The device as recited in claim 1 wherein the second container has an exterior surface and the device further comprises a means for heating the stream in thermal contact with the exterior surface of the second container.
3. The device as recited in claim 1 wherein the membrane is in thermal contact with a heating element.
4. The device as recited in claim 1 wherein the membrane contains palladium.
5. The device as recited in claim 1 wherein the membrane does not contain palladium.
6. The device as recited in claim 1 wherein the device that measures the impurities in the second container is a gas chromatograph.
7. The device as recited in claim 1 , wherein the device that measures the impurities in the second container is a mass spectrometer.
8. A device for measuring impurities in a batch of hydrogen gas, the device comprising:
a first container adapted to receive the batch, the first container having an interior void with a first volume V 1 ;
an adsorbent positioned within said first container, whereby the adsorbent reversibly sequesters the impurities;
a valve in fluid communication with and downstream from the first container;
a second container having an interior void with a second volume V 2 in fluid communication with and downstream from the second container, wherein the valve has an open position and a closed position, and wherein the open position causes the first and second containers to be in fluid communication during receipt, adsorption, and desorption of the batch, and wherein the closed position eliminates fluid communication between the first and second containers after desorption of the batch; and
an analytical device downstream from and in fluid communication with the second container wherein impurities retained in the interior void of the second chamber are concentrated by a factor of
P
h
i
V
1
P
l
o
V
2
with respect to the concentration of the impurities of the batch of hydrogen gas.
9. The device as recited in claim 8 wherein the adsorbent is activated carbon.
10. The device as recited in claim 8 wherein the adsorbent is a zeolite.
11. The device as recited in claim 8 wherein the adsorbent is chosen from the group consisting of silica gel, polymer-based adsorbents, activated alumina, and combinations thereof.