You Do Need power plug adapter while traveling from Brazil to Lebanon.

Here is Why You Need An Adapter

The outlet and plug type used in Lebanon are C, D and G and in Brazil are C and N. This is how they look like.

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N

Lebanon

In Lebanon, outlets of type C, D and G are in use.

Type C

Type D

Type G