Here's a thought:
With the introduction of Diesel Particulate Filters on Class 8 tractors, and now on new pickups, one of the things the trucking industry picked up on was the need to CLEAN the DPF per the mfg. specs.
If the DPF is not cleaned, it will eventually clog and cause the Engine Control Module (the computer) to de-rate the engine and eventually the only thing that engine will have enough power to do is move itself to the nearest shop.
I mention all of this because the inside of lots of DPF's on Class 8 tractors is the same as the inside of a catalytic converter on our pickups: just a big 'ol chunk of ceramic with a b-zillion pin sized holes in it. There's probably more to it than that, but you get the drift.
I just had the DPF on my Class 8 done at a local Kenworth dealer. I had to use them, because they have the machine to clean the element. The element is huge, much bigger than the catalytic converter we're used to seeing hanging under the pickup. Seriously, it's about the size of a small round trash can. Just the element in mine weighs about 60 pounds. I found out on Dec 2, 2011 that the price of this element alone was $3,000. Ouch!
Anywho, when I was in the dealership watching the element get cleaned, I noticed they had a kiln sitting right there. The tech told me that they sometimes have to put the element in the kiln, get it REAL hot so it burns the soot and other nasty stuff into an ash, let it cool, and THEN put the element in the cleaning machine.
The cost was $250 bucks.
Considering the cost of a new catalytic converter (should one choose to go that route) I don't see why the same procedure, including the kiln step, wouldn't work on a catalytic converter that was removed from the truck.
If I were to attempt this, I think I'd use a Sawzall to cut the catalytic converter housing back to make the opening on each end as large as possible. You know, both the input and output exhaust pipe is much smaller than the diameter of the catalytic converter itself. I'd cut the converter off at the exhaust pipe to get it out of the truck, then cut again further up on the flare to make a much larger opening so the cleaning machine can get it's pressurized air nozzles as close to the element as possible.
Make sense?
I suppose it would be possible to have someone put the unit in their kiln for that stage, then just use high pressure air to blow out the catalyst. Just be careful if you decide to do this.... it's going to create LOTS of dust, and that stuff can't be good for your lungs.
OBVIOUSLY you'll want to weld it all back together after the cleaning.