You could use active cooling but the energy requirements would be immense, as you would need to make the heat sink even hotter than the 464+ C atmosphere. You

You could use active cooling but the energy requirements would be immense, as you would need to make the heat sink even hotter than the 464+ C atmosphere. You would basically have to use a crazy high temperature reactor like those envisioned for project Pluto, but setup to somehow produce useful work instead of propulsion, to get the necessary power needed to reach sane cold side temperatures on your heat pump.