Quote from BobHiggins
Thanks for the interesting suggestion and collected tips from ME356. While some Al is desirable for gettering the oxygen, it is not clear, as you point out that the 1:1 Li-Al ratio is preferred. Parkhomov surmised that LiAlH4 was used from the Lugano analyses, but none of those measurements indicate a 1:1 ratio of Li-Al. Measuring the Li is hard and assaying the ratio is hard. So, the Lugano reactor may well have had a different Li-Al ratio than 1:1 and the 1:1 only really comes from Parkhomov. This is test-able. Perhaps the easiest way to change the Li-Al ratio is to include LiH in addition to the LiAlH4. I can set the pressure low to basically whatever I want using my programmable back pressure regulator. Without Al, the Li will not wet to the Ni (only an observation).
For what it's worth he recommended in one post that using only pure lithium in the beginning to at least start obtaining something could be a good idea if external hydrogen admission is available, as apparently it provides the strongest reaction, at the cost of long-term reliability of reactor materials. So, that could be the starting point, which would also simplify the reaction from the point of view of kinetics.
If I am correct, elemental lithium should also be quite reactive with any oxide present. Pure lithium and other alkali metals are often sold in mineral oil for the reason that they can spontaneously combust in air. Actually, in pure form lithium metal may even be too reactive and start attacking the alumina tubes which so far have proven to act fine with LiAlH4 only. Me356 has indeed mentioned that this can be problem, and others who used larger amounts of Li in the mixture with ceramic tubes have witnessed failures as well.
It might be interesting to mention again that the at the time promising GlowStick 5.2 and GlowStick 5.3 experiments used extra Li in the fuel mixture.
It is also pretty hard to get to high enough temperatures to have Li vapor when the heat is being supplied with a heater coil. If, instead, the heat is being supplied as a plasma discharge, the temperatures can easily reach the Li boiling point (almost guaranteed to) while remaining below the Al boiling point (2700C). Additionally, plasma discharge tubes can have a hot center plasma even while the tube itself has its envelope cooled with water, relieving the problem of the apparatus melting. This begins to sound like the case of the dusty plasma of Suhas or even (I hate to say it) Rossi's QuarkX.
In absence of a vacuum system it is indeed hard. If one is available then it's possible to decrease that point to a significantly lower temperature that won't destroy the apparatus right away. For what it's worth, me356 has suggested that "with the right equipment" it's possible to obtain excess heat even at 450°C, implying (in retrospect) if the Li is able to evaporate at that temperature. You would need a pressure of 0.1 Pa to achieve this (and a turbopump).
I am working on a plasma apparatus now for a next round of experiments (with water cooling and flow calorimetry). In the mean time, I will see if I can acquire some LiH or other Li. I will have to check... I may have a small sample of the nano-encapsulated Li.
As far as I recall some people have had issues with that passivated nano-Li powder. Apparently, since it's passivated with CO2, it can end up being depending on batch quality, mostly lithium carbonate and not being able to absorb significant amounts of hydrogen or volatilize like pure Li. It would also free up CO2 at high temperature.
It's been suggested that using a Li wire as a lithium source is fine, indicating that at least in this form it doesn't even need to be intimately mixed with the Ni powder, although it probably depends on reactor geometry. Perhaps it could even come from small strip cut from a Li battery cathode.
Good luck with the plasma system. I guess the focus will soon move away from powder/gas systems.