IIRC, there is only one muzzleloader on the market made to take smokeless powder. It’s out of production now, and it was made on limited production runs by Savage. It uses smokeless powder intended for shotguns. It’s the Savage Model 10ML-II, a .50cal, bolt action, inline muzzleloader.
In short, smokeless powder produces between 2x to 3x the pressure (depending upon the powder) of blackpowder. Using smokeless in a weapon designed for blackpowder is foolish.