Attending an Event (Conference)

Actually, Beijing has 144 hour visa free transit because 72 hour visa free transit has been replaced in Beijing by 144 hour visa free transit a couple of years ago.

All Schengen holder passports with the exception of Norway are eligible for this 144 hour visa free transit option. Anyway, to be eligible, your departing and your arrival country before and after Beijing, have to be different. In other words, your itinerary can look like:

Paris - Beijing - Amsterdam

or

Brussels - Beijing - Paris

Anyway, you are not allowed to travel:

Paris - Beijing - Paris

The latter is a round trip and not a transit. A transit implies the existence of a third country. Please, have this in mind when you book your tickets.