What is Pyrolysis?

Pyrolysis refers to the thermal decomposition of a material on a molecular level. In this case, the goal is to break down long-chain hydrocarbons, or polymers, into short-chain hydrocarbons. To achieve this, the starting material must be heated to several hundred degrees Celsius in an oxygen-free environment to initiate thermal cracking, during which the polymers break apart.

Unfortunately, controlling where these breaks occur is challenging. As a result, this process yields a mix of outputs ranging from pure soot and hydrogen to liquid fractions resembling gasoline and diesel, as well as heavy oils and tar. Using temperature, catalysts, chamber pressure, and additives, these reactions can be better controlled, but for now, this is just the fundamental concept. My goal was to turn an old keyboard into a flammable liquid. Efficiency was not a priority.

WARNING:This experiment is not meant to be replicated. It involves explosive gases, high temperatures, hot flammable liquids, and carcinogenic substances (especially when using Halogenated Polymers). Attempt this only if you truly know what you’re doing—it’s your life at risk. Additionally, tools like welding machines, angle grinders, or lathes can cause severe, life-threatening injuries. Again, it’s your life at stake.

My First Setup

For my first setup, I cast the apparatus out of plaster because I needed something temperature-stable but easy to work with. Inside the plaster block (cast in two steps) was an electric heating coil and a temperature sensor. The top opening was sealed with a clay stopper (unfortunately, a poor choice as the clay cracked over time, though it held airtight until then), and there was an outlet made of a copper tube.

I loaded the removed keys from the keyboard into the apparatus and sealed it. The outlet was connected to a Liebig condenser leading to a container, while the excess gas was burned off via a gas trap.

You can already see a tar-like green residue in the Liebig condenser, likely a combination of tar and copper oxide from the copper tube. This only formed at the beginning, when the chamber wasn’t yet up to temperature.

The results were promising. While somewhat impure, I distilled the product again to remove the tar-like residues. I ended up with a slightly flammable fraction that smelled like a mix of burnt plastic and gasoline, as well as a yellow-brown paste that was almost glue-like after cooling. This encouraged me to continue.

(Unfortunately, the images of this step have been lost.)

The Second Prototype

I needed a larger, more robust reaction chamber. During a visit to the recycling yard, I found an old gas cylinder that was perfect for the second prototype. However, I also needed a burner and a condenser. I decided to go fully DIY.

I used a threaded pipe for the gas connection, a metal rod, a galvanized nut, and a piece of copper tubing. From these, I soldered together a nozzle with a burner, which I then machined on a lathe to create the nozzle hole and thread.

I wasn’t worried about the solder melting because:

1. The nozzle is at the air inlet, meaning it is constantly air-cooled.
2. The gas expands at the nozzle, cooling it further.
3. There is sufficient distance from the flame itself.

The image shows only a test run to check for leaks in the solder joints, which the test passed.

In later trials, the nozzle was even noticeably cooler than the surrounding temperature—another successful test.

The nozzle is mounted at a 45° angle to the inlet to create a passive air draw.

Next, I welded together a burner from square tubing and drilled holes into it. Unfortunately, 4mm holes were too large, so the flame wouldn’t sustain itself. I carefully sealed the holes with weld beads, as I didn’t have a finer drill bit that fit my drill press. While the result isn’t perfectly even, as you can tell from the flames, it was a decent first DIY burner without any gas leaks.

I then filled several liters of water into the opened gas cylinder and attached the burner. Efficiency wasn’t the focus here, but the water started steaming after a few minutes and was boiling within 15 minutes. Test passed.

Now it was time to build the Liebig condenser. I chose copper because it conducts heat well (essential for heat exchangers) and assembled it as shown below. To center the inner tube and seal it against water leaks, I used copper strands from an old cable and soldered the ends shut with a blowtorch and solder on both sides.

I then flared a small copper tube and drilled a tiny hole in the center for the water exchange. I made this in duplicate to create two Liebig condensers.

Unfortunately, the project is currently paused due to time and space constraints. Any updates will be posted here.