Yes, there are. You can go to take the Train No.K89 or 1136 at Beijing West Railway Station. K89 leaves Beijing at 21:00 and reaches Datong at 02:58. 1136 departs from Beijing at 23:03 and arrives in Datong at 05:17. Also you can go to take Train No.K278 at Beijing North Railway Station at 23:30 and reach Datong at 06:36. Additionally, you may take the Train No.2602 at Beijing Railway Station at 23:45 and reach Datong at 06:09. By the way, there are four railway stations in Beijing, including Beijing, Beijing South, Beijing West and Beijing North stations. Why do you choose to depart from Beijing in the late evening? Actually, in the daytime, there are more trains from Beijing to Datong.