Re: Pyrolisis and pressure Questions.

[Peter Verhaart <pverhaart@optusnet.com.au>]

At 08:51 4/01/02 -0500, you wrote:
>  Questions for Chemists,
>     What is the change in the physical reaction of pyrolisis which favors
>higher percentage carbon retention in the biomass/char at higher pressures?

At higher presures the tars and things may not evaporate, instead stay 
within the wood matrix and decompose into carbon and lighter hydrocarbons.

>      Is there any other way to achieve this action at lower pressures?

Possibly by running the process at the lowest temperature at which wood 
will carbonise.

>      How does it change the way O, N, H&C bonds break or form?
>     What bonds are favored?

Wow, that is way beyond me and, if you are interested in burning wood or 
making charcoal, I don't think knowing this is relevant.

>     What happens when H2O is added?

If you want H20 to co-exist with wood at charring temperatures, you have to 
work at elevated pressures.

>      What role does temperature play relative to pressure?
>     Please explain this in detail.

Pressure by itself will not effect chemical changes, combined with elevated 
temperatures, see above.

Snip

Peter Verhaart


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