Am I eligible for 72 hour visa free entry to China?

HI, I am a US Citizen and I will be traveling to Bangkong via Beijing. I will stop by Beijing for around two days and leave for Bangkok. Here's my itineary. LAX-Beijing arrival Saturday 5PM and leave for Bangkok Monday 7:30PM and come back to Beijing just for transit to LAX. I remember getting the answer that I am eligible, but I would like to double confirm on this since my trip is approaching closely. Thank you.