Traveling from Stockholm to Seoul with a stopover in Beijing

I'm planning to fly from Stockholm to Seoul in February. I would like to make a stopover in BJ for 3 days before I go to Seoul. Is it possible to apply for this 72 hours visa-free transit for my stay in BJ and can I apply for that at the airport in BJ? I have a Swedish passport and will make an exchange semester in Korea, so I will also have a visa for Korea.