144 hour visa free transit with 2 separate tickets?

Yes, your itinerary is definitely eligible for visa free transit in Shanghai - twice.

Your first layover will be covered by 24 hour visa free transit because it is shorter than 24 hours and the second one by 144 hour visa free transit and you do not need any kind of visa. It is allowed to travel on separate tickets and on unrelated airlines. This is something that was always allowed.

After your landing in Shanghai the first thing you will do is to approach 24/144 hour visa free transit counter where you will apply for a temporary entry permit by presenting your flight tickets and an accommodation booking for the first overnight. This application is free of any charge and after the permit is granted you will proceed to the immigration and after that outside the airport to spend your time on your own. Have a nice journey.

Thank you Borut