How to Turn Off Twitter Posting to Facebookby Isobel Phillips
It may seem like a good idea to have your Facebook status updated automatically by your tweets, but as you respond to conversations in Twitter, your status updates may not make sense to your Facebook friends. Also, several updates in a short time may irritate them. There is no way to turn this feature off in Twitter; you can only do so from within your Facebook account. (See References 1 and 2)
Log into your Facebook account.
Click Account in the top right-hand corner and select Account Settings from the drop-down menu.
Click the Notifications tab. From the "View Settings for" menu on the right, select Twitter. If Twitter does not appear in the initial list, click "Other apps" and then choose Twitter.
Select the Additional Permissions tab, uncheck the box next to "Update my status without notifying me" and click "OK."