Removing FileVault2 key from memory on lid close
In addition to the destroyfvkeyonstandby option, you also need to specify that pmset is setting hibernatemode 25 for the power management options. 

sudo pmset -a destroyfvkeyonstandby 1 hibernatemode 25


Setting both options ensures that the Mac in question will hibernate (where the contents of the RAM are written to disk) and also have the FileVault 2 key automatically removed from the saved RAM. 

When the laptop is awakened from hibernation, you should see your account icon and a password blank at the FileVault 2 login screen, which would indicate that it had been asleep.



When this setting is set, you may run into some Power Nap-related issues. I have a post on that available from here:

Power Nap, power management settings and FileVault 2