I've studied in the area and, as a bit of a night person, often drove past at night when driving to or from parents. A very cool sight, though the smell is often less pleasant :D - presumably nothing toxic, that would be illegal, but it does smell bad. Kind of like burning plastic, but without the harshest components of that smell.
Anyway, cool that Germany still has the biggest of something ~heavy industry.
I hope you appreciate how nice it is that you can reasonably assume that whatever you're smelling isn't particularly toxic.
I would be curious to know what chemical compounds that you are smelling. Germany has incredibly strict environmental protection laws. As an aside, the waterfront of Kawasaki, Japan is pretty similar, but not one single company. It looks straight from Factorio.