Am I applicable for 72 hour transit visa

Hi there,
I am flying Phnom Penh - Beijing, staying in Beijing for 16 hours and will be leaving the airport to go stay in a hotel - and then flying on to Amsterdam.
Am I applicable to the 72 hour free transit?
And is there anything I need to apply for in advance, or do I just appear at the airport with my passport, onward flight tickets and proof of accomodation?

Thanks, Jennifer