Kosovo is recognized by 23 of 28 EU states, including Germany (and not including Spain). Bavarian independence rarely gets over 2% of the popular vote.
I don't think you've addressed my point.
billymills Kosovo receives support for humanitarian reasons. There was a borderline genocide. Catalonia has had no such thing happen (at least not since Franco, who had a habit of killing most everyone).
And there are plenty of other examples with more support than Bavaria that I could have said. Even just limiting myself to Western Europe I could say Cornwall, Basque Country, Galicia, South Tyrol, Corsica, Åland, Flanders... I could go on. Separatist movements are common across Europe.
In any case, no other country besides Spain is needed to keep Catalonia out of the EU. Any constitutional change has to be approved by all member states. Spain alone can veto. Greece and Bulgaria have kept Macedonia out. Anyone could keep Kosovo out (especially Serbia, if Serbia got in first). Charles de Gaulle vetoed British membership at first, even. The next president Pompidou had to change France's position.
What I don't know is how the procedure to be allowed to be in the Eurozone (when not an EU member) works. The formal EU policy is that only EU states can use the Euro. The only countries not in the EU allowed to use the Euro at the moment are the tiny ones, Andorra, Monaco, San Marino, and the Vatican, which is just practical.
Kosovo and Montenegro also use the Euro, but their cases are very unique and they have no formal agreement. They're relying on just the Euros they have already circulating. And the ECB DOES say they're not happy about it.
Could Catalonia try to do this too? Sure. Could the EU react to it in defense of their monetary policy? Absolutely. Manipulating another country's currency could easily be characterized as an act of war.
At the end of the day I think losing the Euro would be inevitable. Someone else pointed out business leaving the region, which is an even likelier outcome if the Euro is lost. All in all, separating is economically disastrous for Catalonians.