I land in Beijing Oct 26th at 2:10 pm and depart Oct 29 at 8:30 am - Can i get a 72 hour visa?

I land in Beijing Oct 26th at 2:10 pm and depart to Hong Kong Oct 29 at 8:30 am - Can i get a 72 hour free transit during this time as long as I meet the requirements? After visiting Hong Kong, I need to fly back to Beijing November 6th to catch my flight home from Beijing but we will not leave the airport when we come back to fly home. Will I be able to come back to Beijing airport to fly home?