"dennis@home" gurgled happily, sounding
much like they were saying:

I bet they are actually particulate filters.

How do particulate filter burn off the particles? Hint, they use a
catalyst and oxidise them.

Not really - they store, then later inject either extra fuel or additive
to "post-combust" the captured particulates.

Anyway, even then, they're not the same chemistry as a petrol three-way
cat, so aren't susceptible to lead poisoning. If you could still easily
find leaded petrol.