I've definitely made it past 24 hours, and realistically without much hesitation I can say I've done 32 hours awake, BUT I hit this sort of wall where my body is like yeah uhh we're going to just keep yawning and shit.
At first this all starts when you've been up for 17-20 hours, and maybe you can't get to sleep and you feel wide awake, and than as hours creep on and you get to hours 27-34 and you are beginning to fall asleep way too easily and everything but staying up sounds fun.
This was done without the aid of drugs that speed you up or caffeine.