That paper is not too remarkable, it's (1) the first one I found and (2) it uses extraordinarily mild conditions.
The gap between the bench and a commercial factory is immense and there are many areas where people write papers like this for decades but nothing really gets built. I think the usual excuse is that the factory is large enough that it needs to gather waste over a huge area and that transportation of EPS is prohibitively expensive. It doesn't help that styrene monomer is worth only 50 cents a pound, about the same as gasoline.
Wow. The paper from 2022 so surely noone is using this process yet, but are there any plans to? Any idea if it's practical? For expanded polystyrene?