It depends on who is driving Catalan independence, do they also want to be a part of the EU, and if so, then what’s the point?
Catalonians have been thinking about independence from Spain (Castile) for a very long time. They have their own language and I think many of them think of themselves as Catalonian rather than Spanish. Whether or not independence is a good idea or what the politics of the independence movement is, I don’t know.