Let's not forget about the Spanish Civil war where the government was supported by NSDAP and the opposition including Catalonia by USSR.
Majority of Catalonia's region are ultranationalists and communists, a bad combination put together. They're rightful to claim what they had sustained from Franco and the prosecutions along with physical and emotional torture, but it's all part of the past and I see no reason in wanting to secede from Spain at this moment.