12V Microcontroller
I know of no-one making 12v micro's.
The point of micro's going to lower voltages is that as circuit density rises in the core, power dissipation becomes a problem. P=VI, so a 12v micro would create 4x the heat of a 3.3v everything else equal, you would also need non standard voltage interface chips.
Use the 12v to supply a standard micro with 5v/3.3v and use standard interface chips to translate inputs and outputs. I'd use opto isolated inputs and outputs if its in a noisy environment.