Redirecting cold air from a floor-vent to ceiling
The easiest way to deal with this common issue is a vent booster fan, such as this example. It would not take up wall space nor be unsightly.

Without more information, such as the size of the vent opening or mains voltage, it would be impossible to be more specific. A photo of the room and a closeup of the vent might be helpful. Browse HVAC suppliers, online stores, etc.