Most recycle places that buy aluminum cans and the like will buy converters.
You can not. There are no rebuilt cats and it is not legal to sell a used one.
There is no cleaner for a catalytic converter. If it is stopped up you must replace it.
The second oxygen sensor is now used downstream of the catalytic converter to monitor converter operating efficiency.
You can't, period. It is illegal to remove a catalytic converter without installing another one. Besides no modern engine will run correctly with the catalytic converter removed. Suck it up, buy a converter and have it installed.
Platinum is used as the catalyst in a catalytic converter, because this is a precious metal they can be very expensive.
catalytic converter
Depends on what vehicle you are asking about.
Legally you can only replace a catalytic converter with another catalytic converter.
That depends on the engine and the fuel you've used. If the engine starts burning oil a catalytic converter can fail rapidly. Some fuel additives can also cause a catalytic converter to fail prematurely.
Yes
what is the surface area of a catalytic converter
Yes, it has a catalytic converter.