Chlorine

I've gotten into the schools for chemical engineering PhD (learning Catalysis) and would appreciate any input regarding all of your opinions on the PhD school selection standard. My goal is to work in academia eventually, but I am also open to work in industry. I know the ranking changes every year but I think Delaware is 6, Purdue 15, U Penn 15, and Boulder around 18 (US News 2018) in chemical engineering. Since these are all top 20, is there a large significance between Delaware (top 10) and Purdue (top 20), for example? Or should I take care more about general engineering ranking (Purdue), or more general ranking (U Penn)? Or should I only consider the faculty and research area, regardless of the aforementioned ranking things? I appreciate your opinion in advance!