U.S citizen traveling to Thailand with a 7 hr layover in PEK. Do i qualify for the 72 hr visa?

Hi, i will be traveling to Thailand in November 2016 and i have a 7 hr layover to PEK. I really want to check out the city while in transit. I will be fying from the US and i'm also a US citizen. will i qualify for the 72 hr free transit. also is there a fee for it? or is it free of cost?