Can you play a Progress Card even when you get nothing from it?
It appears the FAQ addresses this kind of situation, and the answer is no.
See question number 3 on this page of official catan FAQ:

Progress Cards: General - May I play a Progress Card if playing it has no effect?
If you know beforehand that playing the card will have no effect (e.g., the Foundry card, provided that you are not settling adjacent to a mountains hex): no.
If you have no way of knowing it (e.g., Trade Monopoly): yes.