Do I need visa for a transit flight over China?

Hello. I am holding polish passport. I am flying to Sydney from Warsaw,Poland via China. I have bought 2 separate flight tickets. One ticket is with Lifthansa on the route: Warsaw--Frankfurt-Beijing. 6Hrs layover in Beijing. In Beijing I have to check in again my luggage. The 2nd flight ticket is with ChinaSoutern airlines on the route: Beijing--Guangzhou--Sydney.
For the return flight to Poland I have also 2 separate tickets: one with ChinaSoutern: Auckland--Guangzhou-Bejiing and another ticket with Swiss airlines: Beijing--Zurich--Warsaw.

Do I need chinese entry permit for that trip? or Am I eligible for 24-hrs free transit?
thank you for help
Michal