Can a predicate be a noun?

Yes, a predicate is the verb and all of the Words related to that verb that follow the verb; there can be more than one predicate in a sentence. The Words related the verb included in the predicate can be a noun or nouns. Examples:

This restaurant was recommended by my sister. ('was recommended by my sister' is the complete predicate, 'sister' is a noun)

The Browns live on this street. ('live on this street is the complete predicate, 'street' is a noun)