Albert Barnes Commentary Ezekiel 43:21

"Thou shalt also take the bullock of the sin-offering, and it shall be burnt in the appointed place of the house, without the sanctuary." — Ezekiel 43:21 (ASV)

In the appointed place of the house - A place within the temple-court, but “without the sanctuary” properly so called, that is to say, without the temple and inner court. This was probably the “separate place” .