entitled 72hrs visa free transit if both way stopover in Beijing

Hello
If i am leaving to Beijing on 13Sep 1530hrs arrival, the next day I will be leave to Houston on 14Sep 1500hrs. I believe I am entitle 72hrs free transit. How about for my return trip? If I am flying back from Houston to Beijing and arrives at Beijing 0450hrs , 21Sep, I am intend to stopover again in Beijing for another 1day, out from Beijing to Singapore on 22Sep. Do I still entitled 72hrs free transit?
thanks
Florence, Singapore