Can passengers with a 12 hour layover at Shanghai airport leave the airport and return later flight?

Our flight from Zhangjiajie to SH arrives a 12:05 midnight and then we have to take a connecting flight to San Francisco at 1:00 pm in the afternoon. So we have a 12 hour wait or layover at the SH airport. During this 12 layover, are we allowed to leave the airport to explore the city center and then come back to the airport for our flight to San Francisco at 1:00 pm?