How clean catalyst in gas soldering iron?

Naptha or Coleman white gas should be safe. Failing that ethanol.

A catalyst speeds up a chemical reaction without participating in it.

I think what you have in the tip is a bit of glass wool or a perforated ceramic slug. It should not get fouled with anything because it glows red hot with fire. Anything a solvent could clean out would have been burned off.

More likly you have either bunched up the glass wool inside the tip or it is fouled with carbon (how? maybe you got flux inside or melted some plastic for example).

Probably cannot clean it, just get a new tip.

If you try a solvent (it really shouldn't hurt) , make sure it is plenty dry before relighting. You might also try an ultrasonic bath in soapy water followed by am alcohal rinse. If it is a carbon deposit, you will need the vibration to knock it loose.

If there are any plastic parts on the tip do not use acetone or any cleaner that would damage plastic. Just about any solvent can be used on metals, glass and ceramics.

The message from "AutoTracer" contains these words:

If it's like the soldering iron I used to have, it's platinum coated glass wool. Gives you a flameless butane burn.

Usual failure mode on cheap catalytic soldering irons is the extra-thin catalyst mechanically falling off the glass wool. This isn't fixable.

They'll sometimes clog with flux smoke if you've been working on something particularly grubby. These may still work, but can be hard to light (heating with another torch might get them going). Just using these should be enough to burn off the crud.

The main difference is in the original build quality. The good ones keep working, the cheap ones really don;t last 5 minutes.