Vienna to Bangkok via Pekin

Marcin, the main detail here is that when you travel on 24 hour visa free transit, your right as a passenger is to travel through China absolutely visa free and to stay in the transit area (airside) during your layover. In other words, the exit from the airport is not an inherent passenger's right. However, Chinese authorities usually issue a temporary entry permit to those passengers with longer layovers, layovers during the night and to those who travel with small children.

In your case, you belong to those with long layovers, so I advise you to approach the transit counter (desk) immediately upon your landing in Beijing where you will apply for a temporary entry permit. It is true that hotel booking and a tour booking help in obtaining a permit, but in your case I am almost certain that a permit will be granted because of the length. On your way back, you will do the same thing and when the authorities see that you were already granted on permit, the highest probability is that you will be granted a second one. As you can see, I am always speaking about your good chances because there is no 100% certainty because the exit from the airport while on 24 hour visa free transit is really just a bonus and not a right.