Right outta WWII--woood gasification for engine fuel
Some of the more refined versions filter out the solid particulates, which only leaves the carbon monoxide (CO). Just for reference, the combustion process converts the hydrogen in the HC fuel molecule to water. There's 65% of the power produced by the fuel. Next it converts the carbon elements to CO for another 30% of total power. Finally, CO is oxidized to CO2 yielding the final 5% of total power.
As you can imagine, the engines have almost no power! I did an experiment with it a little over 20 years ago. It was a fun little project, but I abandoned it as impractical.