[Gerrit]

Just checking an old steam engineers handbook to find that steam at 400 F, which is pretty close to 200 C, has a pressure of 250 lbs./sq.in.

My high pressure sprayer (air mist) actually pumps at just over 200lb./sq.in., and it just uses pipe to conduct the spray to the nozzles...

Whatever, I was checking stovetop autoclaves on the 'net (the cheapest boiler-type thing I could find) and they seem rated at only about 160 C.

[Fukudairafarm]

Originally Posted by Gerrit

The name of the catalyst? They might have given it away. Check out the photo at the top of the article referred to above.
Gerrit

You don't have to look at the label, just click on the movie link at the bottom right of the last page of the PDF. You will be brought to the Max Planck Society homepage. Then you can watch the quicktime movie, where they say water is added, with a citric acid catalyst, then it is heated for 12 hours at 180 degrees C.
However, they don't give us the pressure. They only mention it is heated in an autoclave. I wonder if a pressure cooker would work?

[Gerrit]

Thanks for that tip to watch the video! It looks simple doesn't it? A dollop of lemonade with a dash of iron ions heated up to 180C...and presto - charcoal!

But there is a catch - the high pressure boiler required. (Go back to message #33 in this thread to see a letter I posted there from the researcher.) At 180C, the steam pressure in any boiler will build up to about 145 psi. Unfortunately, steam pressure food cookers are only rated for about 15 psi. To get the higher pressures, you need at least a stovetop autoclave.

[Gerrit]

For the do-it-yourselfer to experiment with hydrothermal carbonization, I wonder if an old hydraulic cylinder would be the ideal boiler? They are generally designed for 3,000 psi, which is way more than needed...