Q: Can we raise our hands when the khateeb doing khutba makes dua on friday. Some brothers do it. 

A: This is an act of Bidah. Every Dua does not require the hands to be raised. It is sunnah to not lift the hands. The reward thus is greater to follow the sunnah than do an action of Biddah (innovation.)

May Allah (SWT) accept all our Duas, ameen

Allah Certainly Knows Best.