How Fast Does Lithium Hydride Decompose and Combust in High Temperatures?

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Discussion Overview

The discussion focuses on the decomposition and combustion characteristics of Lithium Hydride (LiH) at high temperatures and pressures. Participants seek data on the decomposition rate of LiH and the kinetics of its combustion with air or oxygen, particularly in the temperature range of 1200 K to 2500 K. The context includes theoretical and experimental aspects relevant to chemical kinetics and computational fluid dynamics (CFD) simulations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning
  • Experimental/applied

Main Points Raised

  • One participant requests specific data on the decomposition rate of LiH at pressures between 1-10 atm and temperatures from 1200 K to 2500 K, expressing a hope that the characteristic time is less than 10E-5 seconds.
  • Another participant suggests resources, including academic papers and books, that may contain relevant data on LiH and its combustion.
  • A participant clarifies the focus on the combustion of solid LiH in a hot air stream and proposes that LiH liquefies before decomposing into lithium and hydrogen, which then reacts with oxygen to form lithium oxide (Li2O).
  • There is a discussion about the need for data on the rate of Li2O production and the assumption that LiH decomposes before reacting with oxygen at elevated temperatures.
  • Suggestions for further reading include studies on corrosion layers formed on lithium compounds and phase diagrams relevant to LiH.
  • Participants mention the limited availability of data on LiH decomposition and its properties, including melting point and solubility in water.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the specific rates of decomposition or combustion of LiH, and multiple competing views and hypotheses about the processes involved remain present throughout the discussion.

Contextual Notes

Participants express uncertainty regarding the availability of data and the conditions under which LiH decomposes and combusts. There are references to various studies and resources, but no definitive conclusions are drawn about the rates or mechanisms involved.

Who May Find This Useful

This discussion may be of interest to researchers and students in the fields of chemistry, materials science, and engineering, particularly those focusing on high-temperature reactions and combustion processes involving lithium compounds.

dom626
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Hi, I'm an italian PhD student (sorry for my english). I'm searching for data on Lithium and Lithium Hydride. In particular:
1) Data concerning LiH decomposition rate @ 1-10 atm and from 1200 K to 2500 K (that is: characteristic time of the decomposition in this range of pressure and temperature: is it < of 10E-5 s? I hope less than...)

2) chemical kinetics (not thermodyn.) data (in Arrhenius form) concerning liquid and gaseous Lithium combustion with air (or oxygen) in the same range of pressure and temperature 1200K-2550K)
Where I can find these data? I have searched into the NIST databases but...nothing!
Can you help me? Thank you for your help and attention!
 
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dom626 said:
Hi, I'm an italian PhD student (sorry for my english). I'm searching for data on Lithium and Lithium Hydride. In particular:
1) Data concerning LiH decomposition rate @ 1-10 atm and from 1200 K to 2500 K (that is: characteristic time of the decomposition in this range of pressure and temperature: is it < of 10E-5 s? I hope less than...)
What is the medium you are interested in?

For oxidation of LiH in air and other inert/oxidizing media, see (pp 25,25,26) http://www.hydrogen.energy.gov/pdfs/review06/stp_2_shaw.pdf

Also, I'd look for more in J. Electrochem. Soc.
 
Tank you Astronuc and Gukul for your suggestions. Really and more precisely the problem under investigation is the combustion in a hot ( more than 1200 K) air stream of a solid grain of LiH in a vented container.My opinion is that LiH first liquifies and after, dragged by the turbulent stream decomposes giving Li and H2. Thus Li reacts with air oxygeh yelding (into this temperature range) Li2O. Now my problem, to make CFD simulations, is: how much rapid is the decomposition? Increasing temperature I think that LiH decomposes before to react with oxygen and only Liquid lithium reacts. To asses this "hypothesys" I need also data about the rate of Li2O production increasing T between 1200 K and about 3000 K but I can't find. Isearching data hoping that the LiH decomposition rate and the Li2O production rate to have characteristic times less than 10-5 seconds...
My last task is to define a reduced set of reaction system to incluse into the CFD software...can you suggest me something more?
Thanks again!
 
Ah, that better defines the problem.

Maybe this paper would be of use - Structure and kinetics of formation and decomposition of corrosion layers formed on lithium compounds exposed to atmospheric gases

Calculation of the thermodynamic characteristics of the systems Li-LiH, Li-LiD, and Li-LiT

From looking at the phase diagram, I think bubbling H2 gas through liquid lithium at 200oC should produce particles of LiH. The question is what material is inert to liquid lithium. I suggest looking up previous studies, e.g., C. E. Messer at al., J. Chem. Eng. Data, vol . 6, 328-330 (1962), or
R. Weil & A. W. Lawson, J. Chem. Phys., vol. 37, p. 2730-2731 (1962) [reported a high-pressure phase transformation in LiH]
or
“Melting of lithium hydride under pressure”,
T. Ogitsu, E. Schwegler, F. Gygi and G. Galli,
Phys. Rev. Lett. vol. 91, 175502(page no.?) (2003).
from eng-tips

http://pubs.acs.org/cgi-bin/abstract.cgi/jpchax/1974/78/i19/f-pdf/f_j100612a013.pdf?sessid=5903#search=%22Li-H%20phase%20diagram%22

Can you find a LiH phase diagram?

Also, one can find limited data for LiH online, e.g.
Decomposes below boiling point at 850°C
Melting point: 680°C
Relative density (water = 1): 0.76-0.77
Solubility in water: reaction

One might find relevant articles in Journal of Physical Chemistry or Journal of Chemical Physics.
 
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Thank yuo Astronuc, and sorry for my late answer (out of my office for a congress...). I will try to follow your suggestions!
 

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