Reacting charcoal & steam to form syngas - details?

[Sheps75]

I know superheated steam will be reduced with amorphous carbon to create syngas.

Where can I find details of the reaction conditions?
I ideally want to know what the lowest temperature this reaction will take place (in the presence of a catalyst if necessary) at or near ambient pressures.

Also does O2 need to be present (as with making town gas)and what ratio of the gases (H2 + CO) are likely?

Thanks for your help.

 

[moltenmetal]

Coal gasification is a big bag of tricks. It's not as simple as reacting coal with steam. Most coal contains substantial amounts of inorganic material, some of which can apparently be catalytic toward the gasification reactions, and all of which has to get back out of your "reactor"- and not up the stack or downstream into whatever is using the sygas.

Petroleum coke contains a different bunch of dogs and cats that have to be considered.

These very practical considerations limit what temperatures and "catalysts", if any, you may be able to use.

 

[Sheps75]

How about with charcoal?

 

[moltenmetal]

Sorry, I missed that you intended to use charcoal as your source of "amorphous carbon". Different than coal or pet coke for sure, but still containing ash- significant quantities given that all the inorganic matter in the original biomass ends up there. It's nowhere near pure carbon. The ash limits what you can do from a catalysis standpoint. If you're interested in the various thermochemical reactions you can find a wealth of information in the literature- this is a very old process.

 

[Sheps75]

Thanks moltenmetal for your helpful response.

Indeed, I had expected the proportion of inorganics in charcoal to be down to an ignorable percentage.

I may consider whether a non-catalyst route should be taken, once I have a better grip of the chemistry. Or alternatively consider how efficient it would be to 'clean-up' the carbon.

Knowing this is, as you say, a very old process, I have been surprised that I have not found a wealth of online resource on these reactions. I expect this is due to me not knowing where to look - it being outside my area.

I would be very much obliged if you could point me in the direction of any online resources that might be suitable. Especially those describing the operational temps & conditions.

Thanks again.

 

[vzeos]

I believe you are talking about water gas. See page 124 of the attached book. There is a discussion of the reaction, the process and a table of reaction products vs. temperature.

http://books.google.com/books?id=Au...chemistry:&as_brr=1&cd=1#v=onepage&q=&f=false

 

[moltenmetal]

Think about it: it doesn't matter if you burn wood, or charcoal made from wood- all the ash in the wood is still there in your furnace when you're done. Gasifying is little different than combustion in that sense.

"Cleaning up" the carbon to remove inorganics will be a big deal- probably a deal-killer.

Again, as to the basic thermochemical reactions (partial oxidation and water-gas shift amongst others), you'll find resources on those easily enough if you spend some effort to look. But the operating conditions may have more to do with ash/slag handling than with the basic chemistry.

 

[unclesyd]

The closest thing to your proposal is the production of wood gas to run cars.
The coke oven byproduct gas process is very complicated and very nasty.
All pyrolysis gas processes are not simple and or very clean due to the aforementioned reasons.

Your mention of catalyst brings up something I wanted to work on. You Can heat a pot of Cast Iron shavings up to around 1500°F and spray with a little water and you get a gas flame. It doesn't have enough H2 to pop so it probably have mostly CO and a little CH4.

Many years ago we heated and cooked with at what was then called water gas which we got for free. This was actually very clean coke oven byproduct gas. it had no odorizer and contain a good percentage of Hydrogen.

http://en.wikipedia.org/wiki/Wood_gas

 

[Sheps75]

Thanks for the replies. I have looked up most of the areas that have been mentioned above previous to posting here.
I think one of the silly mistakes on my pat was when I had been looking up water-gas online I was also getting back info on water-gas shift & this was confusing my amateur chemistry brain.
Now, I have realised my mistake I am beginning to make more sense of this area.

I'm glad metal-steam interactions were mentioned. I have come across some interesting stuff on Iron & SH steam for making H2. Of course, the same outcome is possible with aluminium & H20 at almost ambient temps, but Al is much more energy intensive to make in the first place.

Given that metal-water reactions are exothermic, could a mixture of Fe & Carbon in some kind of matrix push the temps high enough for the Carbon-steam reaction to start?

For making good quality Carbon, I can see that the 'cleaning' of the charcoal source could be a killer, but I would be interested to know what sort of energy costs this relates to.