Flight Dubai - Beijing (one night airport hotel and out in the morning to Mongolia

Hi, as German citizens flying with Emirates to beijing as a stop on the way to Mongolia, do we need a visa beforehand ? We will be staying in the airport hotel. On the way back we will be staying 2 days in Peking central, do we require a visa from here or are we eligable for the 72 hrs upon arrival ? Thanks a million. Tanja