Beijing 15 hours layover, may I apply for a TWOV to get out from airport

Hello,
I'm a citizen of Kazakhstan and a resident of the US. I'm traveling to Astana through Beijing and the layover is 15 hours (Air China). I would like to go to the city for some time and explore, to do that should I apply for the tourist visa or I can apply for a 24-hour-TWOV stamp at the airport? Could you provide information regarding that?
Thanks!