question for 24 hours TWOV

we traveling to the Philippines next month and we have to stay 15 hours lay over in Beijing capital airport.me and the kids our US CITEZENS, my only concern is my wife because she's only a greencard holder.is she gonna be able to qualify for 24 hours TWOV?if she does where can we apply?because we really want to go out and see GREAT WALL and FORBIDDEN CITY.