There's no lead in jet fuel, and I'm just not exactly sure what you mean by aviation being "behind" in fuels in that respect. What's the leading edge supposed to be, in gas turbine technology, other than essentially kerosene?
If you want to make carbon neutral jet fuel based on biomass or direct captured CO2 on the other hand, kero is terribly hard to synthesize. Back in the bad old days politically isolated countries such as Nazi Germany and apartheid South Africa built expensive factories to make gasoline and diesel from coal using the same kind of chemistry that the authors of that paper are using.
Even then the economics were so bad it was an act of desperation and nobody would be attempting to synthesize hydrocarbons for ground transportation today because we have batteries, fuel cells, methane, alcohol and other fuels that can be bio based or synthesized more easily.
The Jet A problem is different from the leaded avgas problem but it comes from the same root that if your engine stalls out because of a fuel problem (say water separates out, freezes, clogs your fuel lines and all the engines fail) you have to hurry and find a place to land pretty quick, whereas if it happens to your car it is not so bad. There’s that any and also an unwillingness to make aviators upgrade their hardware (look at the 5G vs altimeters fight.)
I agree that simple fuels makes more sense to synthesize. Methane is simple, but way more difficult to handle than gasoline. 1-butanol and other liquids would be great, but it is not so easy to produce in scale yet, I believe.
Methane-based planes might have a lower TCO if the industry made the switch but the switch would be hard.
Aviation is 30-40 years behind in fuels (they still use leaded gas.). The kind of Fischer-Tropsch chemistry that these guys are messing with has been basically abandoned for automotive use but is still being pursued for jet fuel because they are afraid to use any fuel which isn’t identical to existing fuels in composition…
Traditionally these processes start with a stream of hydrogen and carbon monoxide which can be made from coal or methane, the economics are gawdawful because the reactions that build up hydrocarbons and break them down have to be closely balanced —- polyethylene formation can be explosive, methane forms quickly if the temperature is too high. What it means is you have a big machine (high capital cost) that makes just a trickle of fuel. In the green era people like these guys are mixing up the chemistry so you can put CO2 in instead.
I have been thinking about how you would make plastic membranes from asteroid materials, we think some asteroids have something that is basically coal and the head end would turn that into ‘petrochemicals’ and might have a lot in common with fuel synthesizers… A lot of chemical processes will create waste CO2 which is precious in that context and has to be recycled.