19 hours layover in Beijing

Your itinerary is definitely eligible for 24 hour visa free transit and you don't need any kind of visa.

To be allowed to exit the airport, you will have to apply for a temporary entry permit at 24 hour visa free transit counter upon your landing in Beijing. Since your layover is very long, you are advised to book your accommodation in advance and to print out a confirmation along with your flight tickets.

Having a confirmation of accommodation booking in hard copy will increase your chances to be granted a temporary entry permit to almost certain level. Anyway, you should have in mind that the issuing of a temporary entry permit is always upon discretion of immigration authorities on a day of arrival.