I'm not sure but i think it is in the 260 or something like that.
you can try some epsode around 260.
When Ulquiorra is fighting Ichigo, he releases in episode 271. Then he releases for a second time in episode 271.
Ulquiorra is the only arrancar that has achieved a second release.
269 ichigo and ulquiorra release there swords
Episode 139
Episode 139
when he fights against Ulquiorra, the 4th espada
Episode 140: Ulquiorra's Scheme, the Moment when the Sun Sets!
Ulquiorra releases his sword in 269 and he goes into his resurrection in episode 270
269 ichigo and ulquiorra release there swords
To answer your question, Ulquiorra's sword/release word is Murcielago (or Murushierago if you read it in the manga since they spell it with katakana so either works fine). Of course you probably already know the answer by the time I answer this haha. Even Better in Japanese it is ムルシエラゴ
Ulquiorra fades away in Episode '272. Ichigo vs. Ulquiorra, Conclusion!'
Episode 139
Episode 139
when he fights against Ulquiorra, the 4th espada
In episode 267,268,269,270,271. btw its ulquiorra
Episode 140: Ulquiorra's Scheme, the Moment when the Sun Sets!
Episode 267
It is a second release by Arrancars. Only Ulquiorra have it.
He did not get the Dragon Sword in any episode, since it is only in a video game.