I don't really know enough about this to comment much, except to agree with whitewave that this sort of situation could occur anywhere and the police would presumably, as in Spain, carry out the will of governement in a similar way.
I don't know why the Catalans want to be independent. I feel torn on issues like this because I tend to think that if more and more groups of people within certain areas want to pull away from the main group then ultimately this would be isolationist and divisive. On the other hand, if there is a possibility that the majority of people within a region seek independence, should the state be allowed to prevent a vote being taken to establish what peoples' wishes are?
It seems to me that when people seek independence from the main body it is usually because they feel they are being ignored or disadvantaged by central government, or they are in a region where valuable resources are located and they wish to keep those resources for themselves rather than share them - or a combination of the two.
It does make me wonder about the notion of "democracy" when it appears acceptable to shut down newspaper offices and generally prevent the dissemination, by any other means, of information and opinion. It does seem that the police are being very brutal and it is surprising and worrying to see a European country experiencing this level of violence. I think these sort of bully boy tactics will just harden attitudes and probably escalate the violence.