Can I use two inferred clauses to get the empty set?

In resolution can I use two inferred clauses to reach the empty set?

Consider this set of clauses: $\{ p \lor q,\neg p \lor r, \neg p \lor \neg r, p \lor \neg q\}$

In this case I infered both $\neg p$ and $p$, can I use resolution on them? Or can I only resolve with the given clauses?

I'm also a bit confused on why I can't infer the empty clause from: $\{p \lor q, \neg p \lor \neg q \}$