Which documents do I need to apply for China tourist visa in Spain?

I am Brazilian, and I am currently studying in the United States with an I-20 form. I will study abroad in Taiwan next semester, so I am planning to go to China for tourism before I start my classes. I have already been to China before with a single-entry visa, and i already have all the plane tickets and my round-trip ticket to Taiwan and China and back to Taiwan confirmed. I have my Taiwanese Student Visa already and a copy of the acceptance letter from the university in Taiwan. I am in Spain in an exchange program (since a month ago) and I have a letter justifying my stay here in Madrid from the school. I do not live in Brazil right now and I will not be returning to the United States before I go to Taiwan and then China. Which documents do I need?