Flights with different airlines, stopover within 72hrs in Beijing on the the way back

I will travel from SGN ( Vietnam ) to Seoul, on the way back I will have flight to Beijing with other airlines and stay there within 72hrs, after that take flight back to SGN. Can 72h Visa-Free transit apply for this case.
1 OZ 734 Z 26MAY 1 HANICN DK1 2300 0520 27MAY E 0 333 S ( Hanoi – Seoul )
2 OZ 333 Z 28MAY 3 ICNPEK DK1 1300 1400 28MAY E 0 333 L ( Seoul – Beijing )
4 CZ 323 R 30MAY 5 PEKCAN HK1 1630 1945 30MAY E CA/ML4WEH ( Beijing – Guangzhou )
5 CZ 371 K 30MAY 5 CANHAN HK1 2155 2315 30MAY E CA/ML4WEH ( Guangzhou – Hanoi )

Thanks