Can Perlite Be Used as Vacuum Insulation for Cryogenic Hydrogen Tanks?

[Q_Goest]

Cryogenic liquid hydrogen tanks are common in industry. These tanks have an inner vessel and an outer vessel. Between the two, the space is sometimes filled with perlite and a vacuum pulled to reduce heat transfer to a minimum to prevent boiling of the liquid hydrogen.

This is the same volcanic rock used in other applications but it is dried in an oven as described here:

Perlite contains from two to five percent of dissolved or chemically combined water. King, Todd, and Kelly (1) report that water above 1.2 percent is very loosely held. M. T. Hunting (2) reported that only that water below 0.75 percent was firmly held.

Processing perlite (3, 4, 5) is a fairly simple operation. Mining is usually an open pit operation. On leaving the mine the ore is crushed, screened, and stored according to size. The ore is then passed into a preheating furnace at 800 to 1000 degrees Fahrenheit, then into a "popping" furnace at a temperature as high as 1800 degrees Fahrenheit. The product from the furnace is then separated and sized in a cyclone separator.

The operation of the "popping" furnace is interesting. As stated above the perlite has a certain amount of loosely bound water. On heating, the water vaporizes and causes the ore to burst, yielding a product of very low density. It is common for an ore with a density of from 68 to 74 pounds per cubic foot to yield a product with a density of from 5 to 7 pounds per cubic foot.

Reference: http://archives.njit.edu/vol01/etd/1950s/1957/njit-etd1957-003/njit-etd1957-003.pdf

Table 1 in this reference is on page 5 and shows typical chemical composition.

Is it possible that this material in the state described (used as vacuum insulation) could adsorb hydrogen gas? Even a small amount of hydrogen?

 

[Q_Goest]

For the record, I asked a friend of mine and got this response:

I don't believe so. Hydrogen is absorbed by many metals in their elemental state but not to my knowledge by metal compounds such as those contained in Perlite.
Perlite contains iron oxides which will not absorb hydrogen unless first reduced to elemental iron. The only way this could occur would be if the iron oxides were reduced by hydrogen first, but this would require heating (eg above 500 deg. centigrade in the presence of hydrogen)

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