Some people say that Catalans want independence from Spain because of the current financial crisis. And many do for exactly that reason. But there is more to it than that. There is also the constant assault from Madrid on the Catalan language and culture. And finally, there is the fact that whereas fascism is still alive and well in Spain, the Catalans don't share that philosophy. The majority party that governs Spain now is the PP, a leftover of the Franco regime. That same party enjoys only a small minority vote in Catalunya. The difference in the way of thinking is illustrated to some extent by recent incidents.
First we have the Via Catalana, the 400-kilometer-long human chain that was held on 11 November as a demonstration that said to the Spanish government and to the world that the Catalans want to vote on a referendum concerning independence. Voting is a basic democratic right and reasonably enough, the Catalans want to exercise it. Voting means people can say "yes" or "no" to the proposition of independence from Spain.
One million six hundred thousand people made the chain. Thirty thousand volunteers helped with the organization. There was no violence, no misshaps. There was one incident in Barcelona where a handful of masked people burned a Spanish flag and a photo of the King. They were not participants in the chain, and no one was hurt.
Then you have the right-wing, fascist extremists who broke into the offices of the Catalan delegation in Madrid on that same day. They entered during an activity that Catalans in Madrid were having, along with their invited guests. There was no human chain in Madrid, but 11 September is Catalunya's National Day -- kind of like the 4th of July -- and they were celebrating with speeches and cava. The fascists violently broke in, destroyed furniture and equipment, and injured people. Some of the hoodlums are relatives of high-ranking government ministers and representatives. Some of them have since been arrested.
A few days later, Catalans in the Spanish Congress demanded that the governmet condemn the fascist act and also that Spain make those fascist groups and political parties illegal (as they are in much of Europe, including Germany). But the government wasn't interested. Why would they be? They had nephews who were involved, and they and/or their colleagues are themselves former participants in or descendents of Spain's own fascist Franco regime. Government ministers, in response pointed to the burning of the Spanish flag in Barcelona saying that it was equivalent to what happened in Madrid ignoring and thus minimizing completely the 1.6 million peaceful people of the Via Catalana and focusing only on the six trouble-makers who burned a flag and were not part of the chain.
You can see for yourself the difference in tone of the Catalan Human Chain of 1.6 million people and the fascist attack in Madrid in the two videos below. You don't have to understand any foreign language to get a good understanding of the two groups.