Can I get a 24-Hour TWOV in Beijing flying from Macau to Ulaanbaatar?

Hello, we are United States and Philippine passport holders. We want to book separate flights from Macau to Beijing and Beijing to Ulaanbaatar. Our first flight has a 15-hour layover in Xiamen. Our second flight from Beijing to Ulaanbaatar is 18 hours after arrival from Xiamen. Will we have any problems obtaining a 24-hour TWOV with either layover?